阅读说明：本技术 一种风力发电机绝缘轴承用复合陶瓷涂层及其制备方法 (Composite ceramic coating for insulating bearing of wind driven generator and preparation method thereof ) 是由 周孟 张毅 田保红 傅丽华 刘勇 李德 薛启明 张志阳 于 2021-06-22 设计创作，主要内容包括：一种风力发电机绝缘轴承用复合陶瓷涂层,包括金属过渡层、陶瓷绝缘层和高分子封闭层,金属过渡层由91wt%的Ni和9wt%的Al组构成的合金喷涂而成,陶瓷绝缘层由复配原料喷涂而成,复配原料由混配粉末和混配粉末质量0.3%的醋酸纤维素粘结剂混合制成,混配粉末包括95-99wt%的α-Al-(2)O-(3)、0.2-2.5wt%的TiO-(2)和0.2-2.5wt%的CeO-(2),高分子封闭层的原料为醇酸树脂改性有机硅浸渍漆和稀释剂。本发明通过涂层材料的选择和喷涂加工工艺的改进,制备得到的复合陶瓷涂层与轴承基体结合强度高、韧性强、不易剥落,致密度高,温度适应范围宽,成本低廉,具有更高的绝缘性能,能够较好的抵抗轴电流的侵蚀。(Wind powerThe composite ceramic coating for the insulated bearing of the power generator comprises a metal transition layer, a ceramic insulating layer and a polymer sealing layer, wherein the metal transition layer is formed by spraying alloy consisting of 91wt% of Ni and 9wt% of Al, the ceramic insulating layer is formed by spraying a compound raw material, the compound raw material is prepared by mixing mixed powder and cellulose acetate binder accounting for 0.3% of the mass of the mixed powder, and the mixed powder comprises 95-99wt% of alpha-Al 2 O 3 0.2-2.5wt% of TiO 2 And 0.2 to 2.5wt% of CeO 2 The material of the high molecular sealing layer is alkyd resin modified organic silicon impregnating varnish and diluent. According to the invention, through the selection of coating materials and the improvement of a spraying processing technology, the prepared composite ceramic coating has the advantages of high bonding strength with a bearing substrate, strong toughness, difficult peeling, high density, wide temperature application range, low cost, higher insulating property and better resistance to corrosion of shaft current.)

1. A composite ceramic coating for an insulating bearing of a wind driven generator is processed on the inner circumferential surface and the outer circumferential surface of an annular insulating bearing, and is characterized in that: the composite ceramic coating comprises a metal transition layer, a ceramic insulating layer and a polymer sealing layer which are sequentially attached to the surface of an insulating bearing from inside to outside, wherein the thickness of the metal transition layer is 50-100 mu m, the metal transition layer is formed by spraying an alloy consisting of 91wt% of Ni and 9wt% of Al, the thickness of the ceramic insulating layer is 100-300 mu m, the ceramic insulating layer is formed by spraying a compound raw material, the compound raw material is prepared by mixing mixed powder and a cellulose acetate binder accounting for 0.3% of the mass of the mixed powder, and the mixed powder comprises 95-99wt% of alpha-Al₂O₃0.2-2.5wt% of TiO₂And 0.2 to 2.5wt% of CeO₂The thickness of the high molecular sealing layer is not more than 50 μm, and the raw materials of the high molecular sealing layer are alkyd resin modified organic silicon impregnating varnish and a diluent.

2. The composite ceramic coating for the insulating bearing of the wind driven generator as claimed in claim 1, wherein: the metal transition layer, the ceramic insulating layer and the polymer sealing layer are respectively attached to the surface of the insulating bearing in a high-speed electric arc spraying mode, an atmospheric plasma spraying mode and an air atomization spraying mode.

3. The composite ceramic coating for the insulating bearing of the wind driven generator as claimed in claim 1, wherein: the raw material of the metal transition layer is Ni-9Al metal wire with the diameter of 1.6mm or 2.0mm when in spraying.

4. The composite ceramic coating for the insulating bearing of the wind driven generator as claimed in claim 1, wherein: the grain diameter of the mixed powder is 1.0-5.0 μm, and alpha-Al₂O₃、TiO₂And CeO₂The purity of (A) is not less than 99.95%.

5. The composite ceramic coating for the insulating bearing of the wind driven generator as claimed in claim 1, wherein: the compound raw materials of the ceramic insulating layer are subjected to freeze drying granulation and then are sprayed.

6. The composite ceramic coating for the insulating bearing of the wind driven generator as claimed in claim 1, wherein: the volume ratio of the alkyd resin modified organic silicon impregnating varnish to the diluent in the raw materials of the high-molecular sealing layer is 4: 1.

7. The preparation method of the composite ceramic coating for the insulating bearing of the wind driven generator according to claim 1, characterized by comprising the following steps:

step one, adopting a water-based alkaline cleaning agent to perform immersion treatment on a bearing ring at 70-90 ℃, after the surface of the bearing ring is degreased, transferring the bearing ring into a drying oven at 80-120 ℃ to perform drying treatment, and preparing the bearing ring with a clean surface for later use;

secondly, shielding and protecting a non-spraying area of the bearing ring by adopting a clamp with metal end covers at two ends, and then carrying out sand blasting treatment on the area to be sprayed of the bearing ring to obtain the bearing ring with a roughened local surface for later use;

thirdly, performing high-speed electric arc spraying treatment on the bearing ring with the partially roughened surface in the second step by using a high-speed electric arc spraying machine and taking a Ni-9Al metal wire as a raw material to obtain a metal transition layer with the thickness of 50-100 microns;

step four, respectively weighing 95-99wt% of alpha-Al according to the weight percentage₂O₃0.2-2.5wt% of TiO₂And 0.2 to 2.5wt% of CeO₂Mixing to obtain mixed powder, adding cellulose acetate binder 0.3 wt% into the mixed powder, mixing to obtain compound raw material, and adding into the mixturePerforming freeze drying granulation treatment, and performing atmospheric plasma spraying on the surface of the metal transition layer in the step three by using the prepared granular material as a raw material by adopting an atmospheric plasma spraying machine to form a ceramic insulating layer with the thickness of 100-300 mu m on the surface of the metal transition layer;

step five, mixing alkyd resin modified organic silicon impregnating varnish and a diluent to prepare a hole sealing agent, and performing air atomization spraying on the surface of the ceramic insulating layer by using an atomization spraying machine to cure the surface of the ceramic insulating layer to form a high-molecular sealing layer;

sixthly, grinding the surface excircle of the polymer sealing layer formed by curing in the step five by adopting an excircle grinding machine to ensure that the thickness of the polymer sealing layer is not more than 50 mu m, and preparing the bearing ring with the composite ceramic coating on the surface for later use;

step seven, cleaning the surface of the bearing ring prepared in the step six by using an ultrasonic cleaner, and then transferring the bearing ring into a drying box at the temperature of 80-120 ℃ for drying treatment to prepare a dried bearing ring for later use;

step eight, carrying out flaw detection inspection on the surface composite ceramic coating on the bearing ring prepared in the step seven by using an ultrasonic flaw detector so as to ensure that the composite ceramic coating has no interface crack, internal laminar crack and unsealed cavity defect;

and step nine, according to a bearing assembly standard program, carrying out accessory assembly on the bearing ring subjected to flaw detection inspection in the step eight, and sequentially carrying out quality inspection and packaging treatment on the manufactured finished bearing to obtain the finished motor insulating bearing.

8. The preparation method of the composite ceramic coating for the wind driven generator insulating bearing according to claim 7, characterized in that: in the second step, the sand blasting treatment is carried out by adopting a self-circulation sand blasting machine, the sand blasting medium during the sand blasting treatment is 16-40 meshes of brown corundum sand, the sand blasting pressure is 0.4-0.6MPa, the sand blasting distance is 100-150mm, the sand blasting angle is 75-85 degrees, the sand blasting time is 5-10 s/ferrule, a step of carrying out high-pressure air blowing impurity removal on the surface of the bearing ferrule is also arranged after the sand blasting treatment, and the subsequent high-speed electric arc spraying treatment needs to be carried out within 4 hours after the sand blasting treatment.

9. The preparation method of the composite ceramic coating for the wind driven generator insulating bearing according to claim 7, characterized in that: in the third step, the spraying voltage during the high-speed electric arc spraying treatment is 30-35V, the spraying current is 170-185A, the spraying distance is 200-300mm, the spraying angle is 90 degrees, and the moving speed of the spray gun is 0.35-0.50 m/s.

10. The preparation method of the composite ceramic coating for the wind driven generator insulating bearing according to claim 7, characterized in that: in the fourth step, the arc current during the atmospheric plasma spraying is 500-600A, the arc voltage is 60-80V, and the main gas flow (Ar + N)₂) Is 2-3.6m³H, auxiliary gas flow (H)₂) Is 0.40-0.75m³The spraying distance is 100-150mm, the feeding speed of the granular materials is 30-45g/min, the moving speed of the spray gun is 0.3-0.6m/s, and the spraying angle is 90 degrees.

Background

Wind power generation is a renewable green and environment-friendly novel energy, and is widely valued by various countries under the conditions that the energy situation is increasingly tense and the requirement for protecting the environment is increasingly urgent. Statistically, wind installations have increased around the world at a rate approaching 30% per year to 1996. By 2020, the installed capacity of the wind power generation in the world is accumulated to 12 billion kW, the wind power generation can generate 3 trillion kW.h per year on average, and the total global power consumption requirement is about 12%. The rapid rise of the wind power industry enables the corresponding wind power equipment to be rapidly developed. However, the wind power equipment is in service in the field throughout the year, the use environment is severe, various extreme environments such as wind blowing, sand hitting, rain, corrosion and the like often occur, and meanwhile, complicated alternating stress and various impact loads occur, which provides a serious challenge to the performance of the wind power equipment.

The bearing is used as a key part in wind power equipment, and the quality performance and the technical level of the bearing determine the running state and the capacity efficiency of the whole wind power system to a certain extent. However, the wind power bearing is located at a weak part in wind power equipment, is often one of main fault points of a wind turbine generator, and becomes a soft rib which restricts the development of the wind power industry in China. According to the actual production condition of the current wind field, the bearing failure of the wind power generator mainly has two forms: one is bearing failure due to cage cracking; another is bearing failure due to galvanic corrosion (i.e., electroerosion).

For wind power plants, induced voltages and currents are typically formed in the circuit between the stator casing, the drive end bearings, the shaft and the non-drive end bearings due to flux imbalances within the machine. When the shaft voltages build up to a certain value and above the breakdown voltage of the bearing lubricant film, they generate an arc in the bearing, discharging along the path of least resistance with the motor bearings. Particularly, at the moment that the inner raceway of the bearing is in metallic contact with the rolling body, the shaft current can reach hundreds of amperes, so that small pits and pits (namely, electric corrosion) are generated on the bearing raceway, the bearing is vibrated and subjected to severe temperature rise change, and the bearing is subjected to electric corrosion failure.

In order to solve the problem of electric corrosion of the wind motor bearing in the service process, the inner ring and the outer ring or the rolling bodies of the bearing are insulated under the common condition, and a conductive path inside the bearing is cut off, so that the failure of the motor bearing caused by electric corrosion damage is effectively avoided. The method is characterized in that a high-insulation ceramic coating is prepared on the outer surfaces of the inner and outer rings of the bearing by a spraying method, and the method is the most common and widely applied insulation mode. The insulating bearing prepared by the process has good insulativity, wear resistance and corrosion resistance, and also has good dimensional stability and wide application range. However, due to the numerous factors affecting plasma spray coatings, this type of insulated bearing product is not mature. Compared with foreign high-end insulating bearing products, the ceramic coating of the domestic insulating bearing product has poor bonding force, low density, poor insulating property and large influence by the environmental temperature and humidity. Therefore, the research and development and the preparation research of the insulating bearing ceramic material of the wind driven generator have very important economic significance and strategic significance.

Disclosure of Invention

The technical purpose of the invention is as follows: through the selection of coating materials and the improvement of a spraying processing technology, the high-performance composite ceramic coating which has high bonding strength with a bearing matrix, strong toughness, difficult peeling, high density, wide temperature application range and low cost is prepared, so that the insulating bearing of the wind driven generator can resist the corrosion of shaft current on the basis of having excellent mechanical performance and has higher insulating performance so as to meet the requirement of the bearing on shaft current ablation resistance and be suitable for wet and dry working environments.

In order to solve the technical problems, the invention adopts the technical scheme that: the composite ceramic coating is processed on the inner circumferential surface and the outer circumferential surface of the annular insulating bearing and comprises a metal transition layer, a ceramic insulating layer and a polymer sealing layer which are sequentially attached to the surface of the insulating bearing from inside to outside, wherein the thickness of the metal transition layer is 50-100 mu m, the metal transition layer is formed by spraying an alloy consisting of 91wt% of Ni and 9wt% of Al, the thickness of the ceramic insulating layer is 100-300 mu m, the ceramic insulating layer is formed by spraying a compound raw material, the compound raw material is prepared by mixing mixed powder and a cellulose acetate binder accounting for 0.3% of the mass of the mixed powder, and the mixed powder comprises 95-99wt% of alpha-Al₂O₃0.2-2.5wt% of TiO₂And 0.2 to 2.5wt% of CeO₂The thickness of the high molecular sealing layer is not more than 50 μm, and the raw materials of the high molecular sealing layer are alkyd resin modified organic silicon impregnating varnish and a diluent.

Preferably, the metal transition layer, the ceramic insulating layer and the polymer sealing layer are respectively attached to the surface of the insulating bearing in a high-speed electric arc spraying mode, an atmospheric plasma spraying mode and an air atomization spraying mode.

Preferably, the raw material of the metal transition layer is Ni-9Al metal wire with the diameter of 1.6mm or 2.0mm during spraying.

Preferably, the particle diameter of the mixed powder is 1.0-5.0 μm, and alpha in the mixed powder-Al₂O₃、TiO₂And CeO₂The purity of (A) is not less than 99.95%.

Preferably, the compound raw materials of the ceramic insulating layer are subjected to freeze drying granulation and then are sprayed.

Preferably, the volume ratio of the alkyd resin modified silicone impregnating varnish to the diluent in the raw materials of the high-molecular sealing layer is 4: 1.

A preparation method of a composite ceramic coating for an insulating bearing of a wind driven generator comprises the following steps:

step one, adopting a water-based alkaline cleaning agent to perform immersion treatment on a bearing ring at 70-90 ℃, after the surface of the bearing ring is degreased, transferring the bearing ring into a drying oven at 80-120 ℃ to perform drying treatment, and preparing the bearing ring with a clean surface for later use;

secondly, shielding and protecting a non-spraying area of the bearing ring by adopting a clamp with metal end covers at two ends, and then carrying out sand blasting treatment on the area to be sprayed of the bearing ring to obtain the bearing ring with a roughened local surface for later use;

thirdly, performing high-speed electric arc spraying treatment on the bearing ring with the partially roughened surface in the second step by using a high-speed electric arc spraying machine and taking a Ni-9Al metal wire as a raw material to obtain a metal transition layer with the thickness of 50-100 microns;

step four, respectively weighing 95-99wt% of alpha-Al according to the weight percentage₂O₃0.2-2.5wt% of TiO₂And 0.2 to 2.5wt% of CeO₂Mixing to obtain mixed powder, adding cellulose acetate binder accounting for 0.3% of the weight of the mixed powder, fully mixing to obtain a compound raw material, carrying out freeze drying and granulation treatment on the compound raw material to obtain a granular material, and carrying out atmospheric plasma spraying on the surface of the metal transition layer in the third step by using the prepared granular material as a raw material by using an atmospheric plasma spraying machine to form a ceramic insulating layer with the thickness of 100-300 mu m on the surface of the metal transition layer;

step five, mixing alkyd resin modified organic silicon impregnating varnish and a diluent to prepare a hole sealing agent, and performing air atomization spraying on the surface of the ceramic insulating layer by using an atomization spraying machine to cure the surface of the ceramic insulating layer to form a high-molecular sealing layer;

sixthly, grinding the surface excircle of the polymer sealing layer formed by curing in the step five by adopting an excircle grinding machine to ensure that the thickness of the polymer sealing layer is not more than 50 mu m, and preparing the bearing ring with the composite ceramic coating on the surface for later use;

step seven, cleaning the surface of the bearing ring prepared in the step six by using an ultrasonic cleaner, and then transferring the bearing ring into a drying box at the temperature of 80-120 ℃ for drying treatment to prepare a dried bearing ring for later use;

step eight, carrying out flaw detection inspection on the surface composite ceramic coating on the bearing ring prepared in the step seven by using an ultrasonic flaw detector so as to ensure that the composite ceramic coating has no interface crack, internal laminar crack and unsealed cavity defect;

and step nine, according to a bearing assembly standard program, carrying out accessory assembly on the bearing ring subjected to flaw detection inspection in the step eight, and sequentially carrying out quality inspection and packaging treatment on the manufactured finished bearing to obtain the finished motor insulating bearing.

Preferably, in the second step, the sand blasting treatment is performed by using a self-circulation sand blasting machine, the sand blasting medium during the sand blasting treatment is 16-40 meshes of brown corundum sand, the sand blasting pressure is 0.4-0.6MPa, the sand blasting distance is 100-150mm, the sand blasting angle is 75-85 degrees, the sand blasting time is 5-10 s/ferrule, a step of performing high-pressure air blowing and impurity removal on the surface of the bearing ferrule is further provided after the sand blasting treatment, the thermal spraying is required to be performed within 4 hours after the sand blasting treatment is finished, and the sand blasting treatment is required to be performed again after more than 4 hours.

Preferably, in the third step, the spraying voltage during the high-speed electric arc spraying treatment is 30-35V, the spraying current is 170-.

Preferably, in the fourth step, the arc current during the atmospheric plasma spraying is 500-600A, the arc voltage is 60-80V, and the main gas flow (Ar + N)₂) Is 2-3.6m³H, auxiliary gas flow (H)₂) Is 0.40-0.75m³The spraying distance is 100-150mm, the feeding speed of the granular materials is 30-45g/min, the moving speed of the spray gun is 0.3-0.6m/s, and the spraying angle is 90 degrees.

The invention has the beneficial effects that:

1. the invention sprays the high-performance composite ceramic coating formed by the metal-ceramic-closed layer group on the non-raceway part of the inner and outer rings of the bearing in sequence and step by step, so that the conventional motor bearing has good electrical insulation performance and insulation strength, can resist the shaft current corrosion of the wind power high-speed motor in the service process, thereby avoiding damaging the bearing and lubricating oil, and prolonging the service life and service life of the bearing. Meanwhile, the composite ceramic coating has excellent performances of good corrosion resistance, high bonding strength, excellent impact toughness, high density, wide temperature application range, low cost and the like through selection and matching of coating materials and improvement of a coating spraying process, and is particularly suitable for extreme environments with severe service environments such as sea, land and the like. According to the determination, the bonding strength of the composite ceramic coating processed on the surface of the insulating bearing is not less than 15 MPa; the porosity is less than or equal to 5%; the electrical strength is ≧ 18 kV/mm; the AC limit withstand voltage value is 50Hz, 2000V-5000V; volume resistivity (DC) ≧ 10¹¹Omega m; the impact energy of the coating is more than or equal to 7.8J; the working temperature range is-40 ℃ to +150 ℃; insulation resistance value: the temperature is 25 plus or minus 2 ℃, and R is more than or equal to 500 megaohms when measured by DC1000V under the condition of normal humidity RH60 plus or minus 3 percent; when measured by DC1000V under the condition of high humidity RH95 +/-3%, R is more than or equal to 100 megaohms, and the comprehensive performance is excellent.

2. The invention adopts a metal transition layer, a ceramic insulating layer and a polymer sealing layer on the structural design of the composite ceramic coating, and the preparation of the composite ceramic coating is carried out by sequentially adhering, superposing and spraying the three layers of structures. Because the thermal expansion coefficient and the elastic modulus of the ceramic insulating layer and the bearing steel are greatly different, the design of the metal transition layer can play a role in buffering so as to effectively reduce the thermal stress of a thermal spraying interface between the ceramic insulating layer and the bearing steel, improve the bonding strength of the subsequent ceramic insulating layer to be sprayed and prevent ceramics with main insulating functionThe stripping of the ceramic insulating layer, especially when the thickness of the ceramic insulating layer is more than 0.3mm, the buffer effect of the metal transition layer is more prominent. The ceramic insulating layer itself is made of alpha-Al₂O₃、TiO₂And CeO₂The three powder materials are combined by the cellulose acetate binder and can supplement each other after being attached to the surface of the metal transition layer by thermal spraying, so that the wide adaptability of the composite ceramic coating in the process of environmental temperature change and service temperature change is effectively improved, and the composite ceramic coating can meet the harsh service environmental conditions of sea, land and the like. The polymer sealing layer can effectively plug and fill micro pores generated in the processing of the ceramic insulating layer by adhering to the outer side of the ceramic insulating layer, so that the surface of the ceramic insulating layer is compact, smooth and uniform, and particularly, when the thickness of the ceramic insulating layer is small (for example, the thickness of the ceramic insulating layer is less than 0.3 mm), communication holes between the ceramic insulating layer and the metal transition layer can be effectively avoided, so that the electric resistance (volume resistance, insulation resistance, voltage resistance and the like) performance of the composite ceramic coating is further improved. The composite ceramic coating has extremely low porosity and higher toughness under the comprehensive action of layer-by-layer stacking, can bear impact load of more than 7.8J without cracking or peeling, and has longer service life and excellent comprehensive performance.

3. The composite ceramic coating of the invention adds a small amount of CeO on the selection of the raw materials of the ceramic insulating layer₂，CeO₂As a rare earth oxide, the rare earth oxide can be rapidly melted into a liquid substance with low viscosity in the process of plasma high-temperature spraying so as to effectively fill alpha-Al with poor melting effect in the ceramic insulating layer₂O₃The hollow space between the grain interfaces reduces the porosity of the ceramic insulating layer and enhances the compactness of the ceramic insulating layer. With CeO₂The addition of the rare earth oxide can also improve the variable range of input power during the construction of the ceramic insulating layer, and has obvious process adaptability.

4. The composite ceramic coating of the invention selects Ni, Al and alpha-Al which are low in price and easy to obtain in the selection of coating preparation raw materials₂O₃、TiO₂And CeO₂And the common materials have large market supply quantity and low price, so that the production cost of the finished insulating bearing is reduced.

5. The preparation process of the composite ceramic coating has simple steps and convenient operation, the processing of the composite ceramic coating can be arranged after the finish machining procedure of the inner bearing ring and the outer bearing ring in the manufacturing process of the common motor bearing and before the bearing assembling procedure, the application range is wide, the technical maturity of the coating material and the spraying equipment is high, and the preparation process is suitable for industrial mass production.

6. The preparation process of the composite ceramic coating fully considers and utilizes the structural transformation of the compound raw materials of the ceramic insulating layer in the plasma spraying process in the processing process. On the one hand, the high-performance electrical insulation characteristic can be obtained by using cheap materials, such as alpha-Al in the spraying process₂O₃Melting the powder, depositing on the surface of the bearing ring at high speed and cooling quickly to obtain alpha-Al powder₂O₃Phase retention, small conversion to gamma-Al₂O₃The layered ceramic insulating layer is formed, the organization structure of the layered ceramic insulating layer is enriched, the structural transformation internal stress of the coating is reduced, and the layered ceramic insulating layer has good self-repairing capability in the spraying process; on the other hand, the mutual solubility characteristic of the compound raw materials in a thermal spraying molten state is utilized to form a solid solution, such as alpha-Al₂O₃With TiO₂Mutual dissolution to form a high-insulation aluminosilicate ceramic series, which can effectively enhance the toughness of the ceramic insulation layer and improve the shock resistance of the ceramic insulation layer in the service process.

7. The invention adopts materials with specific mixture ratio to prepare the composite ceramic coating, and considers that Al in the Ni-9Al alloy can generate exothermic reaction with the oxide on the surface of the ferrule in the electric arc spraying process, thereby playing the dual effects of removing residual oxide film on the surface and improving the temperature heat release of the matrix, and improving the bonding strength between the transition layer and the matrix. The compound raw materials comprise 95-99wt% of alpha-Al according to weight percentage₂O₃0.2-2.5wt% of TiO₂And 0.2 to 2.5wt% of CeO₂Adding TiO with specific proportion₂、CeO₂Powder particles, which can change the chemistry of the ceramic layer by influencing the phase change process of the materialComposition and microstructure, increased nucleation rate, especially of CeO₂The microstructure of the refined coating can be effectively reduced, and the porosity of the insulating ceramic coating is reduced. And finally, hole sealing treatment is carried out by adopting alkyd resin modified organic silicon impregnating varnish and a diluent, so that the insulating property of the composite ceramic coating is further improved.

Detailed Description

In order to make the technical spirit and advantages of the present invention more clearly understandable to examiners of the patent office and particularly to the public, the applicant shall describe in detail below by way of example, but the description of the embodiments is not intended to limit the technical solution of the present invention, and any equivalent changes made according to the inventive concept, which are merely formal and insubstantial, shall be considered to be within the technical solution of the present invention.

The composite ceramic coating is processed on the inner circumferential surface and the outer circumferential surface of the insulating bearing of the annular wind driven generator and comprises a metal transition layer, a ceramic insulating layer and a polymer sealing layer which are sequentially attached to the surface of the insulating bearing from inside to outside, wherein the thickness of the metal transition layer is 50-100 mu m, the metal transition layer is made of a self-fluxing Ni-9Al metal wire with excellent bonding performance, the components of the metal transition layer are 91wt% Ni-9Alwt%, and the specification is 1.6mm or 2.0 mm. The thickness of the ceramic insulating layer is 100-300 mu m, and the spraying material of the ceramic insulating layer is alpha-Al with the purity of not less than 99.95 percent₂O₃Powdered TiO with purity not lower than 99.95%₂And CeO with purity not less than 99.95%₂Powder with a particle size range of 1.0-5.0 μm in terms of alpha-Al₂O₃（95-99wt%）+ TiO₂（0.2-2.5wt%）+ CeO₂(0.2-2.5wt%) and cellulose acetate binder with the mass of 0.3% of the mixed powder, and freeze-drying and granulating to obtain the compound raw material for spraying so as to ensure the uniformity of the components of the ceramic insulating layer. The thickness of the high molecular sealing layer is not more than 50 mu m, the raw materials of the high molecular sealing layer are alkyd resin modified organic silicon impregnating varnish and special diluent, and the high molecular sealing layer is solidified and deposited on the surface of the bearing at room temperature.

The preparation process flow of the composite ceramic coating comprises the following steps: 1 degreasing and deoiling → 2 drying → 3 shielding treatment → 4 sand blasting → 5 high-speed electric arc metal spraying transition layer → 6 plasma spraying ceramic insulating layer → 7 air atomization spraying polymer sealing layer → 8 coating surface grinding → 9 ultrasonic cleaning → 10 drying → 11 coating nondestructive testing → 12 bearing assembly → 13 inspection → 14 packaging and warehousing.

The specific preparation method of the composite ceramic coating comprises the following steps:

1. degreasing and deoiling: the electric heating water tank is used as a degreasing device, and the water-based alkaline cleaning agent is adopted to perform immersion treatment on the bearing ring so as to remove oil pollution caused by machining. The oil stain has strong influence on the bonding strength of the coating. The formula of the water-based alkaline cleaning agent comprises: 50g/L of sodium carbonate, 45g/L of sodium silicate, 1% of polyoxyethylene fatty alcohol ether (dosage by volume) as an emulsifier and 1000ml of deionized water. The water-based alkaline cleaning agent is used at the temperature of 70-90 ℃ and is soaked for 5-10 min. And (4) after the degreasing is finished, checking the degreasing effect by a water-hanging method, and if a water film is continuously distributed on the surface of the bearing ring, indicating that the bearing ring is cleaned.

2. Drying: drying at 80-120 deg.C in an electric heating constant temperature hot air drying oven to remove residual water stain after degreasing.

3. Shielding treatment: the non-spraying area of the bearing ring is shielded, two sides of the bearing ring are protected by a clamp with metal end covers at two ends, each group of 5-10 rings is connected by a threaded mandrel, and the end covers are fixed by nuts.

4. Sand blasting: and carrying out sand blasting treatment on the non-raceway sides of the inner ring and the outer ring. The sand blasting is carried out by adopting a closed self-circulation sand blasting machine, the sand blasting medium is 16-40 meshes of brown corundum sand, the sand blasting pressure is 0.4-0.6MPa, the sand blasting distance is 100-150mm, the sand blasting angle is 75-85 degrees, and the sand blasting time is 5-10 s/ferrule. Sand blasting effect: meanwhile, the method has the effects of removing rust, roughening the surface and increasing the bonding strength of the coating interface. After the sand blasting treatment, the surface of the substrate should be cleaned by dry high-pressure air to blow off residual sand grains and floating dust on the surface, and then the substrate is placed in a clean environment to avoid the surface from being polluted and oxidized by water and impurities in the air. It is required that the thermal spraying must be performed within 4 hours after the blasting, and the blasting must be performed again for more than 4 hours.

5. High-speed electric arc spraying of a metal transition layer: high-speed electric arc spraying is required to be carried out within 2 hours after the sand blasting treatment is finished, a high-speed electric arc spraying machine is adopted for spraying, and a Ni-9Al metal wire rod is used as a raw material, the Ni-9Al metal wire rod comprises 91wt% of Ni-9Alwt%, and the specification is that the diameter is 1.6mm or 2.0 mm. The technological parameters of high-speed electric arc spraying are as follows: the spraying voltage is 30-35V, the spraying current is 170-185A, the spraying distance is 200-300mm, the spraying angle is 90 degrees, and the moving speed of the spray gun is 0.35-0.50 m/s. The thickness of the metal transition layer is 50-100 μm. In the electric arc spraying process, Al in the Ni-9Al alloy can perform exothermic reaction with the surface oxide of the ferrule, so that the dual effects of removing residual oxide films on the surface and improving the temperature heat release of the substrate are achieved, and the bonding strength between the transition layer and the substrate is improved.

6. Plasma spraying of the ceramic insulation layer: directly spraying a ceramic insulating layer on the metal transition layer, wherein the spraying material of the ceramic insulating layer is alpha-Al with the purity of 99.95 percent₂O₃Powder, 99.95% pure TiO₂And CeO with a purity of 99.95%₂The particle size range of the powder is 1.0 to 5.0 mu m, and the alpha-Al is mixed according to the mixed powder₂O₃（95-99wt%）+TiO₂（0.2-2.5wt%）+ CeO₂(0.2-2.5wt%) and cellulose acetate binder accounting for 0.3% of the mixed powder, and granulating by a freeze dryer to obtain the compound raw material for spraying so as to ensure the uniformity of the components of the ceramic insulating layer. Spraying by adopting an atmospheric plasma spraying machine, wherein the process parameters of the plasma spraying are as follows: plasma arc current 500-600A, arc voltage 60-80V, main gas flow (Ar + N)₂)2-3.6m³H, auxiliary gas flow (H)₂）0.40-0.75m³The spraying distance is 100-150mm, the powder feeding speed is 30-45g/min, the moving speed of the spray gun is 0.3-0.6m/s, and the spraying angle is 90 degrees. The thickness of the coating is 100 to 300 μm. alpha-Al in the spraying process₂O₃Melting the powder, depositing on the surface of the bearing ring at high speed and cooling quickly to obtain alpha-Al powder₂O₃Phase retention, small conversion to gamma-Al₂O₃And forming a layered ceramic insulating layer.

7. Air atomization spraying of the polymer sealing layer: when the sprayed ceramic insulating layer is still warm, the hole sealing agent is sprayed on the surface of the ceramic insulating layer in time, and the open pores on the surface of the ceramic insulating layer are filled, so that the sealing effect is achieved. The hole sealing agent material is alkyd resin modified organic silicon impregnating varnish and a special diluent, and the proportion is 4: 1. Spraying the mixture on the surface of the ceramic insulating layer by adopting a common mechanical spray coating method, standing at room temperature for 10min, taking out, and standing for 10 hours to obtain the final product which can be completely cured.

8. Grinding the surface of the coating: and (3) carrying out excircle grinding on the surface of the coating subjected to hole sealing treatment by using a silicon carbide fine grinding wheel to ensure that the thickness of the polymer sealing layer is not more than 50 mu m.

9. Ultrasonic cleaning: and cleaning by using an ultrasonic cleaning machine, cleaning for 1-5 minutes by using deionized water as a cleaning medium, and removing solid particles adhered to the surface of the ferrule and the coating after grinding.

10. Drying: drying at 80-120 deg.C in an electrothermal constant-temperature hot air drying oven to remove residual water stain after ultrasonic cleaning.

11. Nondestructive detection of the coating: and an ultrasonic flaw detector is adopted to detect whether the surface and the sub-surface of the composite ceramic coating have interface cracks, lamellar cracks in the coating, unclosed cavities and other defects.

12. Assembling a bearing: and assembling according to the common bearing assembling standard procedure, and paying attention to not damage the composite electric insulating coating on the non-raceway surface of the bearing ring.

13. And (4) checking: and (4) inspecting the bearing finished product according to the technical standards of enterprises or countries. Due to the particularity of the electric insulation rolling bearing, 100% of inspection is required, and the electric insulation rolling bearing is packaged after being qualified.

14. Packaging and warehousing: according to the size of the electric insulation rolling bearing, single piece or multiple pieces are boxed and packaged, and rust prevention and anti-collision protection are well performed.

Compared with the prior art, the composite ceramic coating material and the preparation method thereof are simple and feasible, can be placed after the finish machining process of the inner bearing ring and the outer bearing ring in the manufacturing process of the common motor bearing and before the bearing assembling process, and have high technical maturity of the coating material and spraying equipment. The metal-ceramic-polymer sealing layer composite ceramic coating is sprayed on the non-raceway part of the inner ring and the outer ring of the bearing, so that the rolling bearing has good electrical insulation and insulating strength, can resist the shaft current corrosion of the motor, particularly the high-speed motor bearing of a fan in service, and avoids damaging the bearing and lubricating oil. In addition, the preparation technology provided by the invention is suitable for industrial batch production.

The insulating bearing prepared by the invention is mainly used for various railway, wind power and mine motor insulating bearings which are in service under severe environmental conditions.

Example 1

The composite ceramic coating for the insulating bearing of the wind driven generator is formed by processing composite ceramic coatings on the inner circumferential surface and the outer circumferential surface of a common bearing, wherein the composite ceramic coatings comprise a metal transition layer, a ceramic insulating layer and a polymer sealing layer which are sequentially attached to the surface of the bearing from inside to outside, the thickness of the metal transition layer is 70 mu m, the metal transition layer is made of Ni-9Al metal wire rods with the specification of 2mm diameter and the components of 91wt% Ni-9 Alwt%; the ceramic insulating layer has a thickness of 120 μm, and is made of alpha-Al with a purity of 99.95% or less and a powder particle size range of 1.0-5.0 μm₂O₃Powder, TiO₂Powder and CeO₂The mixture ratio of the powder to the powder is 98wt% alpha-Al₂O₃+1.8 wt% TiO₂+0.2wt% CeO₂When the mixed powder is used, the mixed powder is mixed with 0.3% of cellulose acetate binder, and the mixed powder is subjected to freeze drying and granulation to obtain a compound raw material for spraying; the thickness of the high-molecular sealing layer is 30 mu m, and the high-molecular sealing layer is made of alkyd resin modified organic silicon impregnating varnish and a special diluent in a volume ratio of 4: 1.

The specific preparation method comprises the following steps:

1. degreasing and deoiling: 50g/L of sodium carbonate, 45g/L of sodium silicate, 1000ml of water-based alkaline cleaning agent with the emulsifier being polyoxyethylene fatty alcohol ether (the dosage of 1% by volume) and the deionized water being 1000ml are put into an electric heating water tank, the electric heating water tank is started, the temperature of the water-based alkaline cleaning agent in the electric heating water tank is raised to 75 ℃, the bearing ring is put into the electric heating water tank for immersion and deoiling treatment, and the immersion time is 8 min. And (4) after the degreasing is finished, checking the degreasing effect by a water-hanging method, and if a water film is continuously distributed on the surface of the bearing ring, indicating that the bearing ring is cleaned.

2. Drying: and drying by adopting an electric heating constant-temperature hot air drying box at the drying temperature of 110 ℃, and drying residual water stains after the degreasing process.

3. Shielding treatment: the non-spraying area of the bearing ring is shielded, two sides of the bearing ring are protected by a clamp with metal end covers at two ends, each group of 5-10 rings is connected by a threaded mandrel, and the end covers are fixed by nuts.

4. Sand blasting: and carrying out sand blasting treatment on the non-raceway sides of the inner ring and the outer ring by adopting a closed self-circulation sand blasting machine. The sand blasting medium during the treatment is 30-mesh brown corundum sand, the sand blasting pressure is 0.45MPa, the sand blasting distance is 110mm, the sand blasting angle is 75 degrees, and the sand blasting time is 8 s/ferrule. After the sand blasting treatment, the residual sand grains and floating dust on the surface of the matrix are blown off by dry and clean high-pressure air, and then the matrix is placed in a clean environment to avoid the surface from being polluted and oxidized by water and impurities in the air.

5. High-speed electric arc spraying of a metal transition layer: adopting a high-speed electric arc spraying machine to perform high-speed electric arc spraying within 4 hours after the sand blasting treatment is finished, wherein Ni-9Al metal wire rods with the diameter of 2mm are used as raw materials during spraying, and the process parameters are set as follows: spraying voltage of 31V, spraying current of 170A, spraying distance of 230mm, spraying angle of 90 degrees and spray gun moving speed of 0.35m/s, and spraying to obtain a metal transition layer with the thickness of 70 μm.

6. Plasma spraying of the ceramic insulation layer: alpha-Al with the purity not lower than 99.95 percent and the granularity range of 1.0 to 5.0 mu m is adopted₂O₃Powder, TiO₂Powder and CeO₂The powder is taken as a raw material and is prepared according to the proportion of 98wt percent of alpha-Al₂O₃+1.8 wt% TiO₂+0.2wt% CeO₂The mixed powder and 0.3% cellulose acetate binder are mixed according to the proportion, and the mixture is granulated by a freeze dryer to obtain the compound raw material for spraying. An atmospheric plasma spraying machine is adopted, and the process parameters are set as follows: plasma arc current 520A, arc voltage 70V, main gas flow (Ar + N)₂)3.5m³H, auxiliary gas flow (H)₂）0.55m³H, spraying distance of 100mm, powder feeding speed of 38g/min and spray gun moving speed of 0.6 m-And s, spraying at an angle of 90 degrees to obtain the ceramic insulating layer with the thickness of 0.1 mm.

7. Air atomization spraying of the polymer sealing layer: mixing alkyd resin modified organic silicon impregnating varnish and a special diluent in a volume ratio of 4:1 to prepare a hole sealing agent, spraying the hole sealing agent on the surface of a ceramic insulating layer by adopting a common mechanical spraying and coating method when the residual temperature of the ceramic insulating layer still exists, standing at room temperature for 10min, taking out, and standing for 10 h to completely cure the hole sealing agent.

8. Grinding the surface of the coating: and (3) carrying out excircle grinding on the surface of the coating subjected to hole sealing treatment by using a silicon carbide fine grinding wheel to enable the thickness of the polymer sealing layer to be a set value.

9. Ultrasonic cleaning: and cleaning for 1-5min by using deionized water as a cleaning medium and an ultrasonic cleaning machine to remove solid particles adhered to the surface of the ferrule and the coating after grinding.

10. Drying: and drying the water stain by adopting an electric heating constant-temperature hot air drying box at the temperature of 100 ℃ so as to dry the water stain remained after the ultrasonic cleaning procedure.

11. Nondestructive detection of the coating: and an ultrasonic flaw detector is adopted to detect whether the surface and the sub-surface of the composite ceramic coating have interface cracks, lamellar cracks in the coating, unclosed cavities and other defects.

12. Assembling a bearing: and assembling according to the common bearing assembling standard procedure, and paying attention to not damage the composite electric insulating coating on the non-raceway surface of the bearing ring.

13. And (4) checking: and (4) inspecting the bearing finished product according to the technical standards of enterprises or countries. Due to the particularity of the electric insulation rolling bearing, 100% of inspection is required, and the electric insulation rolling bearing is packaged after being qualified.

14. Packaging and warehousing: according to the size of the electric insulation rolling bearing, single piece or multiple pieces are boxed and packaged, and rust prevention and anti-collision protection are well performed.

The performance of the composite ceramic coating of the insulating bearing prepared in the embodiment is measured, and the bonding strength is 26.5 MPa; porosity 2.08%; the electrical strength is 19.6 kV/mm; ac limit withstand voltage value: 50Hz, 4869V; volume resistivity (DC) 1.54X 10¹¹Omega m; the impact energy of the coating is 11.3J; working temperatureDegree range: -40 ℃ to +150 ℃; insulation resistance value: r =510 megaohms measured at room temperature 25 ± 2 ℃ under DC1000V with conventional humidity RH60 ± 3%; r =103 megaohms measured at DC1000V under conditions of high humidity RH95 ± 3%.

Example 2

The composite ceramic coating for the insulating bearing of the wind driven generator is formed by processing composite ceramic coatings on the inner circumferential surface and the outer circumferential surface of a common bearing, wherein the composite ceramic coatings comprise a metal transition layer, a ceramic insulating layer and a polymer sealing layer which are sequentially attached to the surface of the bearing from inside to outside, the thickness of the metal transition layer is 50 mu m, the metal transition layer is made of Ni-9Al metal wire rods with the specification of 1.6mm in diameter and the components of 91wt% Ni-9 Alwt%; the ceramic insulating layer has a thickness of 100 μm, and is made of alpha-Al with a purity of 99.95% or less and a powder particle size range of 1.0-5.0 μm₂O₃Powder, TiO₂Powder and CeO₂The mixture ratio of the powder to the powder is 99wt% alpha-Al₂O₃+0.2wt% TiO₂+0.8wt% CeO₂When the mixed powder is used, the mixed powder is mixed with 0.3% of cellulose acetate binder, and the mixed powder is subjected to freeze drying and granulation to obtain a compound raw material for spraying; the thickness of the high-molecular sealing layer is 50 mu m, and the high-molecular sealing layer is made of alkyd resin modified organic silicon impregnating varnish and a special diluent in a volume ratio of 4: 1.

The specific preparation method comprises the following steps:

1. degreasing and deoiling: the procedure was as in example 1, except that the immersion/degreasing treatment was carried out at a temperature of 70 ℃ for 8 min.

2. Drying: this step was identical to example 1, only the drying temperature was set to 120 ℃.

3. Shielding treatment: this procedure was in accordance with example 1.

4. Sand blasting: the procedure is the same as that of example 1, the sand blasting medium adopted in the sand blasting treatment is 16-mesh brown corundum sand, the sand blasting pressure is 0.5MPa, the sand blasting distance is 120mm, the sand blasting angle is 70 degrees, and the sand blasting time is 5 s/ferrule.

5. High-speed electric arc spraying of a metal transition layer: adopting a high-speed electric arc spraying machine to perform high-speed electric arc spraying within 4 hours after the sand blasting treatment is finished, wherein Ni-9Al metal wire rods with the diameter of 1.6mm are used as raw materials during spraying, and the process parameters are set as follows: spraying voltage of 33V, spraying current of 175A, spraying distance of 240mm, spraying angle of 90 degrees and spray gun moving speed of 0.40m/s, and spraying to obtain a metal transition layer with thickness of 50 μm.

6. Plasma spraying of the ceramic insulation layer: alpha-Al with the purity not lower than 99.95 percent and the granularity range of 1.0 to 5.0 mu m is adopted₂O₃Powder, TiO₂Powder and CeO₂The powder is used as raw material according to the proportion of 99wt% alpha-Al₂O₃+0.2wt% TiO₂+0.8wt% CeO₂The mixed powder and 0.3% cellulose acetate binder are mixed according to the proportion, and the mixture is granulated by a freeze dryer to obtain the compound raw material for spraying. An atmospheric plasma spraying machine is adopted, and the process parameters are set as follows: plasma arc current 500A, arc voltage 65V, main gas flow (Ar + N)₂) 3.6m³H, auxiliary gas flow (H)₂）0.45m³The spraying distance is 120mm, the powder feeding speed is 40g/min, the moving speed of a spray gun is 0.4m/s, the spraying angle is 90 degrees, and the ceramic insulating layer with the thickness of 100 microns is obtained by spraying.

The subsequent steps 7-14 are all in accordance with example 1.

The performance of the composite ceramic coating of the insulating bearing prepared in the embodiment is measured, and the bonding strength is 33.1 MPa; porosity 2.39%; the electrical strength is 22.8 kV/mm; ac limit withstand voltage value: 50Hz, 3256V; volume resistivity (DC) 1.69X 10¹¹Omega m; the impact energy of the coating is 10.2J; working temperature range: -40 ℃ to +150 ℃; insulation resistance value: r =505 megaohms measured at room temperature 25 ± 2 ℃ under DC1000V with conventional humidity RH60 ± 3%; r =106 megaohms measured at DC1000V under conditions of high humidity RH95 ± 3%.

Example 3

The composite ceramic coating for the insulating bearing of the wind driven generator is formed by processing composite ceramic coatings on the inner circumferential surface and the outer circumferential surface of a common bearing, wherein the composite ceramic coatings comprise a metal transition layer, a ceramic insulating layer and a polymer sealing layer which are sequentially attached to the surface of the bearing from inside to outside, the thickness of the metal transition layer is 100 mu m, and the metal transition layer is made of materials with the specification of 2mm in diameterNi-9Al metal wire with the composition of 91wt% of Ni-9 Alwt%; the ceramic insulating layer has a thickness of 200 μm, and is made of alpha-Al with a purity of 99.95% or less and a powder particle size range of 1.0-5.0 μm₂O₃Powder, TiO₂Powder and CeO₂The mixture ratio of the powder to the powder is 97.4wt% of alpha-Al₂O₃+2.4wt% TiO₂+0.2wt% CeO₂When the mixed powder is used, the mixed powder is mixed with 0.3% of cellulose acetate binder, and the mixed powder is subjected to freeze drying and granulation to obtain a compound raw material for spraying; the thickness of the high-molecular sealing layer is 40 mu m, and the high-molecular sealing layer is made of alkyd resin modified organic silicon impregnating varnish and a special diluent in a volume ratio of 4: 1.

The specific preparation method comprises the following steps:

1. degreasing and deoiling: the procedure was as in example 1, except that the immersion/degreasing treatment was carried out at 90 ℃ for 7 min.

2. Drying: this step was identical to example 1, except that the drying temperature was set to 80 ℃.

3. Shielding treatment: this procedure was in accordance with example 1.

4. Sand blasting: the steps are consistent with the embodiment 1, the sand blasting medium adopted in the sand blasting treatment is 40-mesh brown corundum sand, the sand blasting pressure is 0.4MPa, the sand blasting distance is 150mm, the sand blasting angle is 85 degrees, and the sand blasting time is 7 s/ferrule.

5. High-speed electric arc spraying of a metal transition layer: adopting a high-speed electric arc spraying machine to perform high-speed electric arc spraying within 4 hours after the sand blasting treatment is finished, wherein Ni-9Al metal wire rods with the diameter of 2mm are used as raw materials during spraying, and the process parameters are set as follows: spraying voltage of 30V, spraying current of 185A, spraying distance of 250mm, spraying angle of 90 degrees and spray gun moving speed of 0.45m/s, and spraying to obtain a metal transition layer with the thickness of 100 mu m.

6. Plasma spraying of the ceramic insulation layer: alpha-Al with the purity not lower than 99.95 percent and the granularity range of 1.0 to 5.0 mu m is adopted₂O₃Powder, TiO₂Powder and CeO₂The powder was used as a raw material according to 97.4wt% of alpha-Al₂O₃+2.4wt% TiO₂+0.2wt% CeO₂Taking the mixed powder and 0.3 percent of acetate fiber by massAnd mixing the vegetable binders, and granulating by a freeze dryer to obtain the compound raw material for spraying. An atmospheric plasma spraying machine is adopted, and the process parameters are set as follows: plasma arc current 550A, arc voltage 60V, main gas flow (Ar + N)₂) 3.0m³H, auxiliary gas flow (H)₂）0.75m³The spraying distance is 150mm, the powder feeding speed is 45g/min, the moving speed of a spray gun is 0.3m/s, the spraying angle is 90 degrees, and the ceramic insulating layer with the thickness of 200 mu m is obtained by spraying.

The subsequent steps 7-14 are all in accordance with example 1.

The performance of the composite ceramic coating of the insulating bearing prepared in the embodiment is measured, and the bonding strength is 22.8 MPa; porosity 1.43%; the electric strength is 26.9 kV/mm; ac limit withstand voltage value: 50Hz, 2896V; volume resistivity (DC) 1.38X 10¹¹Omega m; the impact energy of the coating is 9.6J; working temperature range: -40 ℃ to +150 ℃; insulation resistance value: room temperature 25 ± 2 ℃, normal humidity RH60 ± 3% under DC1000V measurement, R =512 megaohms; measured at DC1000V under high humidity RH95 ± 3% conditions, R =107 megaohms.

Example 4

The composite ceramic coating for the insulating bearing of the wind driven generator is formed by processing composite ceramic coatings on the inner circumferential surface and the outer circumferential surface of a common bearing, wherein the composite ceramic coatings comprise a metal transition layer, a ceramic insulating layer and a polymer sealing layer which are sequentially attached to the surface of the bearing from inside to outside, the thickness of the metal transition layer is 60 mu m, the metal transition layer is made of Ni-9Al metal wire rods with the specification of 1.6mm in diameter and the components of 91wt% Ni-9 Alwt%; the ceramic insulating layer has a thickness of 300 μm, and is made of alpha-Al with a purity of 99.95% or less and a powder particle size range of 1.0-5.0 μm₂O₃Powder, TiO₂Powder and CeO₂The mixture ratio of the powder to the powder is 97wt% of alpha-Al₂O₃+2.1wt% TiO₂+0.9wt% CeO₂When the mixed powder is used, the mixed powder is mixed with 0.3% of cellulose acetate binder, and the mixed powder is subjected to freeze drying and granulation to obtain a compound raw material for spraying; the thickness of the high-molecular sealing layer is 30 mu m, and the high-molecular sealing layer is made of alkyd resin modified organic silicon impregnating varnish and a special diluent in a volume ratio of 4: 1.

The specific preparation method comprises the following steps:

1. degreasing and deoiling: the procedure was as in example 1, except that the immersion/degreasing treatment was carried out at 80 ℃ for 5 min.

2. Drying: this step was identical to example 1, only the drying temperature was set to 110 ℃.

3. Shielding treatment: this procedure was in accordance with example 1.

4. Sand blasting: the procedure is the same as that of example 1, and the blasting medium adopted only in the blasting treatment is 20-mesh brown corundum sand, the blasting pressure is 0.6MPa, the blasting distance is 100mm, the blasting angle is 80 degrees, and the blasting time is 10 s/ferrule.

5. High-speed electric arc spraying of a metal transition layer: adopting a high-speed electric arc spraying machine to perform high-speed electric arc spraying within 4 hours after the sand blasting treatment is finished, wherein Ni-9Al metal wire rods with the diameter of 1.6mm are used as raw materials during spraying, and the process parameters are set as follows: spraying voltage of 32V, spraying current of 180A, spraying distance of 300mm, spraying angle of 90 degrees and spray gun moving speed of 0.5m/s, and spraying to obtain a metal transition layer with thickness of 60 mu m.

6. Plasma spraying of the ceramic insulation layer: alpha-Al with the purity not lower than 99.95 percent and the granularity range of 1.0 to 5.0 mu m is adopted₂O₃Powder, TiO₂Powder and CeO₂The powder is used as raw material according to 97wt% of alpha-Al₂O₃+2.1wt% TiO₂+0.9wt% CeO₂The mixed powder and 0.3% cellulose acetate binder are mixed according to the proportion, and the mixture is granulated by a freeze dryer to obtain the compound raw material for spraying. An atmospheric plasma spraying machine is adopted, and the process parameters are set as follows: plasma arc current 600A, arc voltage 80V, main gas flow (Ar + N)₂) 2.2m³H, auxiliary gas flow (H)₂）0.4m³The spraying distance is 110mm, the powder feeding speed is 30g/min, the moving speed of a spray gun is 0.5m/s, the spraying angle is 90 degrees, and the ceramic insulating layer with the thickness of 300 mu m is obtained by spraying.

The subsequent steps 7-14 are all in accordance with example 1.

Properties of composite ceramic coating for insulating bearing prepared in this exampleMeasuring, and measuring the bonding strength to be 19.9 MPa; porosity 1.65%; the electrical strength is 23.5 kV/mm; ac limit withstand voltage value: 50Hz, 4125V; volume resistivity (DC) 2.15X 10¹¹Omega m; the impact energy of the coating is 8.1J; working temperature range: -40 ℃ to +150 ℃; insulation resistance value: room temperature 25 ± 2 ℃, normal humidity RH60 ± 3% under DC1000V measurement, R =509 megaohms; r =101 megaohms measured at DC1000V under conditions of high humidity RH95 ± 3%.

Example 5

The composite ceramic coating for the insulating bearing of the wind driven generator is formed by processing composite ceramic coatings on the inner circumferential surface and the outer circumferential surface of a common bearing, wherein the composite ceramic coatings comprise a metal transition layer, a ceramic insulating layer and a polymer sealing layer which are sequentially attached to the surface of the bearing from inside to outside, the thickness of the metal transition layer is 80 mu m, the metal transition layer is made of Ni-9Al metal wire rods with the specification of 2mm diameter and the components of 91wt% Ni-9 Alwt%; the thickness of the ceramic insulating layer is 260 μm, and the material is alpha-Al with purity not lower than 99.95% and powder granularity range of 1.0-5.0 μm₂O₃Powder, TiO₂Powder and CeO₂The mixture ratio of the powder to the powder is 95wt% alpha-Al₂O₃+2.5wt% TiO₂+2.5wt% CeO₂When the mixed powder is used, the mixed powder is mixed with 0.3% of cellulose acetate binder, and the mixed powder is subjected to freeze drying and granulation to obtain a compound raw material for spraying; the thickness of the high-molecular sealing layer is 50 mu m, and the high-molecular sealing layer is made of alkyd resin modified organic silicon impregnating varnish and a special diluent in a volume ratio of 4: 1.

The specific preparation method comprises the following steps:

1. degreasing and deoiling: the procedure was as in example 1, except that the immersion/degreasing treatment was carried out at 75 ℃ for 10 min.

2. Drying: this step was the same as in example 1, except that the drying temperature was set to 100 ℃.

3. Shielding treatment: this procedure was in accordance with example 1.

4. Sand blasting: the procedure is the same as that of example 1, and the sand blasting medium adopted in the sand blasting treatment is 30-mesh brown corundum sand, the sand blasting pressure is 0.5MPa, the sand blasting distance is 120mm, the sand blasting angle is 75 degrees, and the sand blasting time is 8 s/ferrule.

5. High-speed electric arc spraying of a metal transition layer: adopting a high-speed electric arc spraying machine to perform high-speed electric arc spraying within 4 hours after the sand blasting treatment is finished, wherein Ni-9Al metal wire rods with the diameter of 2mm are used as raw materials during spraying, and the process parameters are set as follows: spraying voltage is 35V, spraying current is 185A, spraying distance is 200mm, spraying angle is 90 degrees, moving speed of a spray gun is 0.5m/s, and a metal transition layer with thickness of 80 microns is obtained by spraying.

6. Plasma spraying of the ceramic insulation layer: alpha-Al with the purity not lower than 99.95 percent and the granularity range of 1.0 to 5.0 mu m is adopted₂O₃Powder, TiO₂Powder and CeO₂The powder is used as raw material according to the proportion of 95wt% alpha-Al₂O₃+2.5wt% TiO₂+2.5wt% CeO₂The mixed powder and 0.3% cellulose acetate binder are mixed according to the proportion, and the mixture is granulated by a freeze dryer to obtain the compound raw material for spraying. An atmospheric plasma spraying machine is adopted, and the process parameters are set as follows: plasma arc current 560A, arc voltage 75V, main gas flow (Ar + N)₂)2.0m³H, auxiliary gas flow (H)₂）0.5m³The spraying distance is 130mm, the powder feeding speed is 35g/min, the moving speed of a spray gun is 0.6m/s, the spraying angle is 90 degrees, and the ceramic insulating layer with the thickness of 260 mu m is obtained by spraying.

The subsequent steps 7-14 are all in accordance with example 1.

The performance of the composite ceramic coating of the insulating bearing prepared in the embodiment is measured, and the bonding strength is 29.2 MPa; the porosity is 2.1%; the electrical strength is 27.1 kV/mm; ac limit withstand voltage value: 50Hz, 3581V; volume resistivity (DC) 2.23X 10¹¹Omega m; the impact energy of the coating is 9.3J; working temperature range: -40 ℃ to +150 ℃; insulation resistance value: room temperature 25 ± 2 ℃, normal humidity RH60 ± 3% under DC1000V measurement, R =519 megaohms; r =112 megaohms measured at DC1000V under conditions of high humidity RH95 ± 3%.

The above examples are provided for clarity of illustration only and are not intended to limit the invention to the particular embodiments described. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And obvious variations or modifications can be made without departing from the scope of the invention as claimed.