阅读说明：本技术 一种温控器陶瓷材料及其制备方法 (Ceramic material for temperature controller and preparation method thereof ) 是由 李国文 于 2021-08-27 设计创作，主要内容包括：本发明公开一种温控器陶瓷材料及其制备工艺,涉及陶瓷材料加工技术领域。本发明公开的温控器陶瓷材料由以下重量份数的原料制备：α-Al-(2)O-(3)微粉80～90份、γ-氧化铝5～10份、MgO-Al-(2)O-(3)-CaO玻璃粉3～5份、氧化硅2～5份、粘结剂2～3份和分散剂1.5～2份；其制备工艺为：α-Al-(2)O-(3)微粉和MgO-Al-(2)O-(3)-CaO玻璃粉表面分别采用偶联剂进行改性,然后进行混合、反应,制得预混合物；再与陶瓷材料其他组分进行混合研磨,制得浆料；造粒、烧结,即可。本发明提供了一种温控器陶瓷材料,主要用于温控器壳体、支撑件和传动件上,具有较高的机械强度、耐压强度和绝缘电阻,具有较低的热导率和优异的磨损性,保证了温控器的安全使用,并大大延长了温控器的使用寿命。(The invention discloses a temperature controller ceramic material and a preparation process thereof, and relates to the technical field of ceramic material processing. The invention discloses a ceramic material for a temperature controller, which is prepared from the following raw materials in parts by weight: alpha-Al 2 O 3 80-90 parts of micro powder, 5-10 parts of gamma-alumina and MgO-Al 2 O 3 3-5 parts of CaO glass powder, 2-5 parts of silicon oxide, 2-3 parts of binder and 1.5-2 parts of dispersant; the preparation process comprises the following steps: alpha-Al 2 O 3 Fine powder and MgO-Al 2 O 3 Modifying the surface of CaO glass powder by using a coupling agent respectively, and then mixing and reacting to prepare a premix; then mixing and grinding the mixture with other components of the ceramic material to prepare slurry; and (5) granulating and sintering. The invention provides a ceramic material for a temperature controller, which is mainly used on a shell, a supporting piece and a driving piece of the temperature controller, has higher mechanical strength, compressive strength and insulation resistance, and has lower heat conductivity and insulation resistanceExcellent wearability, guaranteed the safe handling of temperature controller to the life of temperature controller has been prolonged greatly.)

1. The ceramic material for the temperature controller is characterized by consisting ofThe following raw materials in parts by weight are prepared: alpha-Al₂O₃80-90 parts of micro powder, 5-10 parts of gamma-alumina and MgO-Al₂O₃3-5 parts of CaO glass powder, 2-5 parts of silicon oxide, 2-3 parts of binder and 1.5-2 parts of dispersant;

the preparation process of the ceramic material sequentially comprises the following steps:

P1.α-Al₂O₃surface modification of the micro powder: alpha-Al is added₂O₃Adding the micro powder and diisopropyl bis (triethanolamine) titanate into a proper amount of toluene solvent for mixing, stirring for 4-6h at 80-90 ℃, filtering, washing and drying to obtain surface-modified alpha-Al₂O₃Micro powder, wherein the addition amount of the di (triethanolamine) diisopropyl titanate is alpha-Al₂O₃2-4% of the micro powder;

P2.MgO-Al₂O₃surface modification of CaO glass frits: adding MgO-Al₂O₃adding-CaO glass powder and 3- (2, 3-epoxypropoxy) propyl trimethoxy silane into a proper amount of toluene solvent, mixing, stirring for 3-4h at 100-110 ℃, filtering, washing and drying to obtain silane modified MgO-Al₂O₃CaO glass powder, the addition amount of the 3- (2, 3-epoxypropoxy) propyl trimethoxy silane is MgO-Al₂O₃-5-8% by mass of CaO glass powder;

p3. premixing: the prepared surface modified alpha-Al₂O₃Fine powder and silane-modified MgO-Al₂O₃Adding CaO glass powder into a proper amount of toluene solvent, fully and uniformly mixing, then adding tributylamine, reacting for 4-5 hours at the temperature of 100-120 ℃ in an inert atmosphere, performing suction filtration, and performing vacuum drying to obtain a premix;

and P4, mixing materials: adding the pre-mixture, gamma-alumina, silicon oxide, a binder and a dispersant into a high-speed ball mill, and grinding for 4-6 hours, wherein the dispersion medium is deionized water, and the grinding medium is high-purity alumina ceramic balls, so as to obtain uniformly mixed slurry;

p5. and granulating: spray drying and granulating the slurry to prepare ceramic granules;

and P6, sintering: and carrying out cold isostatic pressing on the ceramic granules to obtain a ceramic blank, then carrying out surface modification on the ceramic blank, placing the ceramic blank in a high-temperature sintering furnace, carrying out pressureless sintering in an inert atmosphere, heating to 1300 ℃, keeping the temperature for 20-30 min, and naturally cooling to obtain the ceramic material for the temperature controller.

2. The ceramic material for temperature controller of claim 1, wherein the MgO-Al is₂O₃The molar ratio of Mg, Al and Ca in the CaO glass frit is 1: (0.1-0.2): (0.3-0.4).

3. The ceramic material for temperature controller of claim 2, wherein the MgO-Al is₂O₃The preparation method of the CaO glass powder comprises the following steps:

s1, putting magnesium nitrate hexahydrate and calcium acetate into 80 wt% acetic acid solution until the magnesium nitrate hexahydrate and the calcium acetate are completely dissolved, then adding aluminum isopropoxide, stirring for 10-15 min, then heating to 70-80 ℃, and stirring for 1-1.5 h to obtain mixed gel;

s2, drying the mixed gel at 90-100 ℃, ball-milling for 2-3 h, placing the mixed gel in a sintering furnace, heating to 650-800 ℃, and preserving heat for 2-3 h to obtain MgO-Al2O3-CaO glass powder.

4. The ceramic material for temperature controller of claim 1, wherein the α -Al is₂O₃The particle size of the micro powder is 3-5 μm, the average particle size of the gamma-alumina is 0.25-1 μm, and the MgO-Al₂O₃The CaO glass powder and the silicon oxide are ground and sieved by a 2000-mesh sieve.

5. The ceramic material for temperature controller of claim 1, wherein the tributylamine is added in an amount of the α -Al₂O₃8-12% of the mass of the micro powder.

6. The ceramic material for the temperature controller of claim 1, wherein the average particle size of the ceramic granules obtained by spray drying and granulation is 5-20 μm.

7. The temperature controller ceramic material of claim 1, wherein the pressureless sintering in step P6 is performed in three stages: heating to 650-700 ℃ at the speed of 3-5 ℃/min, and keeping the temperature for 45-60 min; then heating to 900-1000 ℃ at the speed of 5-10 ℃/min, and preserving heat for 30-60 min; and then heating to 1100-1200 ℃ at the speed of 3-5 ℃/min, and preserving the heat for 2-3 h.

8. The ceramic material for the temperature controller according to claim 1, wherein the binder is prepared from (3-4) by mass: 1 of a mixture of polyamide wax and polyethylene wax.

9. The temperature controller ceramic material of claim 1, wherein the dispersant is one of a polyethylene glycol-based polymer or a polycarboxylate-based polymer.

Technical Field

The invention belongs to the technical field of ceramic processing, and particularly relates to a temperature controller ceramic material and a preparation method thereof.

Background

The temperature controller is a series of automatic control elements, also called temperature control switches, temperature protectors and temperature controllers, which are used for controlling the operation of equipment to achieve ideal temperature and energy-saving effects and are widely applied to various products such as household appliances, motors, refrigeration or heating and the like according to different types of temperature controllers. At first, because the ceramic manufacturing process is relatively laggard, a shell and a support piece of a temperature controller for fixedly supporting and wrapping the temperature controller (such as a metal element and the like) are made of plastic products, but the plastic products are easy to soften at high temperature, so that the electrical appliance product has great potential safety hazard, in the 90 s of 20 th century, Germany starts to develop a ceramic temperature controller switch box formed by dry pressing and succeeds in this way, ceramic materials are widely used in the temperature controller switch from this point, and the safety use performance of the electrical appliance product is guaranteed.

Ceramics having electrical and magnetic properties can be used in the electronics industry and are called electronic ceramics. In recent years, electronic ceramic materials have been widely used as key materials in many high-tech fields such as electronics, communications, automatic control, information computers, aerospace and the like due to their advantages such as excellent mechanical strength, high temperature and high humidity resistance, radiation resistance, insulation, dielectric properties and the like. At present, the ceramic part material applied to the temperature controller is mainly 95 aluminum oxide ceramic, and the ceramic part material has the characteristics of high mechanical strength, good wear resistance and corrosion resistance, good thermal stability, large insulation resistance, matched expansion coefficient with a chip and the like. In the using process of the temperature controller, the temperature controller is required to have higher compressive strength, better heat insulation and excellent insulating property, but the thermal conductivity of the alumina ceramic is higher (the thermal conductivity of the pure alumina ceramic is more than 20W/(m.K)), so that the heat insulation property of the ceramic part of the temperature controller is poor; and the alumina ceramics have larger brittleness, low impact resistance and frangibility, which affects the use effect of the alumina ceramics on the temperature controller. The ceramic piece of the temperature controller is directly contacted with the metal temperature sensing piece, and the metal temperature sensing piece can deform towards the front side and the back side along with the change of the environmental temperature, so that friction is generated between the metal temperature sensing piece and the ceramic piece, the metal temperature sensing piece is easy to wear, the service life of the temperature controller is influenced, and therefore the ceramic material of the temperature controller needs to have excellent wear resistance.

Disclosure of Invention

The invention provides a ceramic material for a temperature controller, which is mainly used for a shell, a supporting piece and a driving piece of the temperature controller, and mainly aims to provide an alumina ceramic material which has higher mechanical strength, compressive strength and insulation resistance, lower heat conductivity and excellent wearability, ensures the safe use of the temperature controller and greatly prolongs the service life of the temperature controller.

In order to achieve the purpose of the invention, the invention provides a ceramic material for a temperature controller, which is prepared from the following raw materials in parts by weight: alpha-Al₂O₃80-90 parts of micro powder, 5-10 parts of gamma-alumina and MgO-Al₂O₃3-5 parts of CaO glass powder, 2-5 parts of silicon oxide, 2-3 parts of binder and 1.5-2 parts of dispersant;

the preparation process of the ceramic material sequentially comprises the following steps:

P1.α-Al₂O₃surface modification of the micro powder: alpha-Al is added₂O₃Adding the micro powder and diisopropyl bis (triethanolamine) titanate into a proper amount of toluene solvent for mixing, stirring for 4-6h at 80-90 ℃, filtering, washing and drying to obtain surface-modified alpha-Al₂O₃Micro powder, wherein the addition amount of the di (triethanolamine) diisopropyl titanate is alpha-Al₂O₃2-4% of the micro powder;

P2.MgO-Al₂O₃surface modification of CaO glass frits: adding MgO-Al₂O₃adding-CaO glass powder and 3- (2, 3-epoxypropoxy) propyl trimethoxy silane into a proper amount of toluene solvent, mixing, stirring for 3-4h at 100-110 ℃, filtering, washing and drying to obtain silane modified MgO-Al₂O₃CaO glass powder, the addition amount of the 3- (2, 3-epoxypropoxy) propyl trimethoxy silane is MgO-Al₂O₃-5-8% by mass of CaO glass powder;

p3. premixing: the prepared surface modified alpha-Al₂O₃Fine powder and silane-modified MgO-Al₂O₃Adding CaO glass powder into a proper amount of toluene solvent, fully and uniformly mixing, then adding tributylamine, reacting for 4-5 hours at the temperature of 100-120 ℃ in an inert atmosphere, performing suction filtration, and performing vacuum drying to obtain a premix;

and P4, mixing materials: adding the pre-mixture, gamma-alumina, silicon oxide, a binder and a dispersant into a high-speed ball mill, and grinding for 4-6 hours, wherein the dispersion medium is deionized water, and the grinding medium is high-purity alumina ceramic balls, so as to obtain uniformly mixed slurry;

p5. and granulating: spray drying and granulating the slurry to prepare ceramic granules;

and P6, sintering: and carrying out cold isostatic pressing on the ceramic granules to obtain a ceramic blank, then carrying out surface modification on the ceramic blank, placing the ceramic blank in a high-temperature sintering furnace, carrying out pressureless sintering in an inert atmosphere, heating to 1300 ℃, keeping the temperature for 20-30 min, and naturally cooling to obtain the ceramic material for the temperature controller.

Further, the MgO-Al₂O₃The molar ratio of Mg, Al and Ca in the CaO glass frit is 1: (0.1-0.2): (0.3-0.4).

Further, the MgO-Al₂O₃The preparation method of the CaO glass powder comprises the following steps:

s1, putting magnesium nitrate hexahydrate and calcium acetate into 80 wt% acetic acid solution until the magnesium nitrate hexahydrate and the calcium acetate are completely dissolved, then adding aluminum isopropoxide, stirring for 10-15 min, then heating to 70-80 ℃, and stirring for 1-1.5 h to obtain mixed gel;

s2, drying the mixed gel at 90-100 ℃, ball-milling for 2-3 h, placing the mixed gel in a sintering furnace, heating to 650-800 ℃, and preserving heat for 2-3 h to obtain MgO-Al2O3-CaO glass powder.

Further, the alpha-Al₂O₃The particle size of the micro powder is 3-5 μm, the average particle size of the gamma-alumina is 0.25-1 μm, and the MgO-Al₂O₃The CaO glass powder and the silicon oxide are ground and sieved by a 2000-mesh sieve.

Further, the addition amount of the tributylamine is the alpha-Al₂O₃8-12% of the mass of the micro powder.

Furthermore, the average particle size of the ceramic granules obtained by spray drying granulation is 5-20 μm.

Further, the pressureless sintering in the step P6 is performed in three stages: heating to 650-700 ℃ at the speed of 3-5 ℃/min, and keeping the temperature for 45-60 min; then heating to 900-1000 ℃ at the speed of 5-10 ℃/min, and preserving heat for 30-60 min; and then heating to 1100-1200 ℃ at the speed of 3-5 ℃/min, and preserving the heat for 2-3 h.

Further, the binder is prepared from the following components in percentage by mass (3-4): 1 of a mixture of polyamide wax and polyethylene wax.

Further, the dispersing agent is one of polyethylene glycol-based polymer or polycarboxylate-based polymer.

The invention achieves the following beneficial effects:

1. the invention adopts MgO-Al₂O₃The CaO glass powder is used as an addition auxiliary agent and is added into the alumina matrix, so that the sintering temperature of the ceramic material is obviously reduced, the strength, toughness and wear resistance of the ceramic material are improved, and the thermal conductivity of the ceramic material is obviously reduced. MgO-Al₂O₃The CaO glass powder contains a small amount of calcium hexaaluminate (CaAl)₁₂O₁₉) Magnesium aluminate spinel (MgAl)₂O₄) The two components have higher activity in a high-temperature process, are easy to form a liquid phase with an alumina matrix and are beneficial to grain boundary diffusion and migration, so that the density of the alumina matrix is improved, and the hardness and compressive strength of the invention are further improved; the calcium hexaluminate and the magnesium aluminate spinel have low thermal conductivity, and a small amount of calcium hexaluminate and magnesium aluminate spinel is dispersed in an alumina matrix, so that the high efficiency of a heat transmission path can be reduced, and the thermal conductivity of the invention is obviously reduced; MgO-Al₂O₃CaO glass powder is CaO and Al₂O₃And MgO, which is added into the alumina matrix, improves the dispersion effect of the ceramic material, and each component in the composite component can interact and influence each other, can act on the alumina matrix more effectively, has better effect than the three components which are respectively added into the alumina matrix and mixed and dispersed, ensures that the calcium, magnesium and aluminum components can be dispersed in the alumina matrix more uniformly, reduces lattice defects, refines crystal grains, promotes sintering densification, improves the densification rate, namely the high-temperature sintering time is shorter, and effectively improves the compressive strength and the wear resistance of the ceramic material.

2. The alumina matrix in the present invention is alpha-Al₂O₃The gamma-alumina has high specific surface area, high activity and strong adsorbability, and is added into an alumina matrix to improve the binding force among the components of the ceramic material and reduce the content of the ceramic materialThe sintering temperature is high, so that the alumina ceramic material with a compact structure is formed at a lower sintering temperature; the gamma-alumina with higher activity can form liquid phase or solid solution with each component of the ceramic material at the sintering temperature, and the components are tightly combined under the action of surface tension to cause rapid volume shrinkage, porosity reduction and density increase, and the gamma-alumina, CaO, MgO and SiO₂The combination of these components, the resulting solid solution dispersed in the alumina matrix, further reduces the thermal conductivity of the present invention.

3. The invention uses alpha-Al with proper proportion and proper grain size₂O₃And gamma-alumina, the compactness of the ceramic material is improved, and the thermal conductivity of the ceramic material is reduced. The invention adopts the gamma-alumina with the average grain diameter of 0.25-1 mu m, the grain diameter of the gamma-alumina is smaller, the gap of the filler can be reduced, the compactness of the invention is improved, and the strength and the toughness of the invention are improved. If the grain diameter of the gamma-alumina is larger, namely equal to or larger than that of other components of the ceramic material, the gaps among the components are larger, the porosity is increased, the density is increased, the densification of the ceramic material is reduced, and the improvement of the strength and the toughness is not facilitated; if the grain size of the gamma-alumina is less than 0.25 μm, the gamma-alumina is easy to agglomerate and is easy to be unevenly distributed in the ceramic material, so that the mechanical strength of the invention is influenced, and the smaller the grain size is, a heat conduction network is easy to form, the heat conductivity coefficient of the material is improved, and the heat conductivity of the invention is influenced. The invention uses alpha-Al with proper grain diameter₂O₃And gamma-alumina can significantly improve the mechanical strength and reduce the thermal conductivity of the invention.

4. According to the invention, SiO is added₂As a sintering aid, the ceramic material has low cost and wide source, is easy to form a low-melting-point glass phase with alumina at a crystal boundary, reduces the number and area of the crystal boundary along with continuous sintering, reduces the co-dissolution temperature of the crystal boundary, becomes a liquid phase at a low sintering temperature, promotes sintering and improves the density of the ceramic material; the invention adds proper amount of SiO₂Can be reacted with Al at high temperature₂O₃React at the grain boundary to form a small amount of mullite structure which can be coated on the surface of alumina so as to ensure thatThe anion cavity on the surface is eliminated, thereby the alpha-Al is treated₂O₃The growth of the crystal grains plays a role of inhibiting, and the crystal grains are refined, so that the compressive strength of the invention is improved.

5. The invention utilizes the coupling agent to react with alpha-Al₂O₃Fine powder and MgO-Al₂O₃CaO glass powder is subjected to surface modification, reactive groups are respectively introduced, then the reactive groups on the surfaces of the two modified powder materials are subjected to chemical reaction to generate bonding, and further a composite material with a coating structure is formed, so that the two materials can be fully combined, and the alpha-Al content is improved₂O₃Fine powder and MgO-Al₂O₃The bonding force of-CaO glass powder solves the problem of MgO-Al₂O₃The CaO glass powder is non-uniformly dispersed, so that the compactness of the ceramic material is improved, and the strength and the toughness of the ceramic material are further improved; due to MgO-Al₂O₃The thermal conductivity of the CaO glass frit is low, and this special cladding structure also significantly reduces the thermal conductivity of the ceramic material and ensures the high insulation resistance of the present invention.

α-Al₂O₃The micro powder is subjected to surface modification by bis (triethanolamine) diisopropyl titanate containing alcoholic hydroxyl groups to enable alpha-Al₂O₃Introducing alcoholic hydroxyl on the surface of the micro powder; MgO-Al₂O₃the-CaO glass powder is subjected to surface modification by 3- (2, 3-epoxypropoxy) propyl trimethoxy silane containing epoxy groups to enable MgO-Al₂O₃Introducing epoxy groups on the surface of the CaO glass powder; in the presence of tributylamine alkaline chemical, the alcoholic hydroxyl group can make the ring opening of the epoxy group react, thereby leading to alpha-Al₂O₃Fine powder and MgO-Al₂O₃The CaO glass powder is tightly combined together, so that the density, the strength and the toughness of the composite material are improved.

6. alpha-Al of the invention₂O₃The micro powder is modified by bis (triethanolamine) diisopropyl titanate, except for introducing alcoholic hydroxyl, titanium is also introduced, so that titanium dioxide is formed in the high-temperature process, and the titanium dioxide is introduced to form a solid solution with alumina in the sintering process, thereby reducing the sintering temperature of the invention and promoting the crystallizationThe grains grow, but under the action of inhibiting the grains from growing by the silicon oxide, the grains of the ceramic material are in a proper range, so that the use amount of the titanate coupling agent and the silicon oxide is limited, and the ceramic material can achieve the optimal performance.

7. The invention uses proper proportion of Mg, Al and Ca to form MgO-Al₂O₃CaO glass powder, and the preparation method is simple, easy to operate and low in cost. Too high a calcium content leads to an increase in the apparent porosity of the ceramic material and a decrease in the acid resistance; if the calcium content is too low, a eutectic system is not easily formed, a dense microstructure is not easily formed, and the reduction in thermal conductivity is reduced. If the content of the alumina is too high, the bonding force between the glass powder and an alumina matrix is easily caused, the compactness of the ceramic material is influenced, and further the strength and the toughness are influenced; if the content of the aluminum oxide is too low, composite components are not easily formed in the glass powder, the bonding force of each component of the glass powder is influenced, and the reduction of the thermal conductivity of the invention is greatly influenced.

8. The invention adopts a staged pressureless sintering mode to carry out high-temperature sintering, can ensure that different components of the ceramic material fully react, melt, crystallize, diffuse and the like at different temperatures, increases the density of the ceramic material, has better crystallinity, forms uniformly refined grains, reduces the porosity and improves the strength and the toughness of the invention. The dispersant is a high molecular polymer, and an inorganic substance is not adopted, so that the introduction of other metal ions is reduced, and therefore, the influence factors of the performance of the ceramic material are reduced, the structural performance of the ceramic material is easy to control, and the ceramic material has an excellent dispersing effect.

9. The invention adopts alpha-Al₂O₃And gamma-alumina as an alumina ceramic matrix, and alpha-Al₂O₃Fine powder and MgO-Al₂O₃Surface-modified CaO glass frit and bonding using MgO-Al₂O₃The ceramic material with high density is obtained by taking CaO glass powder and silicon oxide as additives, has low thermal conductivity, excellent bending property, fracture toughness, insulativity and high temperature resistance, and has easily obtained raw materials and lower cost. The preparation process is simple and has parametersEasy control and stable production.

Detailed Description

The technical solutions in the embodiments of the present invention are clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

alpha-Al for use in the invention₂O₃The micro powder is provided by Zhengzhou Xideli chemical new material limited company, and the type number of the micro powder is Xideli XDL-A2; gamma-alumina is available from bovas nanotechnology (Ningbo) Inc.

The temperature controller ceramic material and the preparation process thereof according to the present invention will be described with reference to the following embodiments.

Example 1

The preparation process of the ceramic material for the temperature controller comprises the following steps:

P1.α-Al₂O₃surface modification of the micro powder: 800g of alpha-Al₂O₃Adding the micro powder and 16g of diisopropyl bis (triethanolamine) titanate into 2L of toluene solvent, mixing, stirring for 6h at 80 ℃, cooling to room temperature, filtering the mixture, quickly washing a filter cake with toluene for 3 times to remove residual titanate coupling agent components, and drying the product in a vacuum oven to obtain the surface modified alpha-Al₂O₃And (5) micro-powder.

P2.MgO-Al₂O₃Surface modification of CaO glass frits: 50g of MgO-Al₂O₃Adding CaO glass powder and 4g of 3- (2, 3-epoxypropoxy) propyltrimethoxysilane into 500mL of toluene solvent for mixing, stirring for 4h at 100 ℃, cooling to room temperature, filtering the mixture, quickly washing a filter cake for 3 times by using toluene to remove residual silane coupling agent components, and drying the product in a vacuum oven to obtain silane modified MgO-Al₂O₃CaO glass frit.

P3. premixing: the prepared surface modified alpha-Al₂O₃Micropowder andsilane-modified MgO-Al₂O₃And (2) adding CaO glass powder into 5L of toluene solvent, fully and uniformly mixing, then adding 64g of tributylamine, reacting for 5 hours at the temperature of 100 ℃ under an inert atmosphere to enable epoxy groups to fully react with alcoholic hydroxyl groups, then carrying out suction filtration through a vacuum pump to obtain precipitates, and drying in a vacuum oven to remove the solvent to obtain the premix.

And P4, mixing materials: adding the pre-mixture, 100g of gamma-alumina, 50g of silicon oxide, 15g of polyamide wax, 5g of polyethylene wax and 20g of polyethylene glycol-based polymer FS10 into a high-speed ball mill, grinding for 4 hours at the speed of 450r/min, wherein the dispersion medium is 2kg of deionized water, and the grinding medium is high-purity alumina ceramic balls, and grinding to obtain uniformly mixed slurry.

P5. and granulating: and carrying out spray drying granulation on the slurry to obtain the ceramic granules with the average particle size of 5-20 microns.

And P6, sintering: carrying out cold isostatic pressing on the ceramic granules, wherein the pressure of the cold isostatic pressing is 80MPa, obtaining a ceramic blank, then carrying out surface modification processing on the ceramic blank, placing the ceramic blank in a high-temperature sintering furnace, carrying out pressureless sintering in an inert atmosphere, and carrying out the pressureless sintering in three sections: heating to 650 ℃ at the speed of 3 ℃/min, and keeping the temperature for 60 min; then heating to 900 ℃ at the speed of 5 ℃/min, and preserving heat for 60 min; then the temperature is raised to 1100 ℃ at the speed of 5 ℃/min, and the temperature is preserved for 3 h. And then heating to 1300 ℃, preserving the temperature for 30min, and naturally cooling to obtain the ceramic material of the temperature controller.

The above-mentioned MgO-Al₂O₃The preparation method of the CaO glass powder comprises the following steps:

s1, putting 256g of magnesium nitrate hexahydrate and 61.2g of calcium acetate into 80 wt% acetic acid solution until the magnesium nitrate hexahydrate and the calcium acetate are completely dissolved, then adding 31.6g of aluminum isopropoxide, stirring for 10-15 min, heating to 70-80 ℃, and stirring for 1-1.5 h to obtain mixed gel;

s2, drying the mixed gel at 90-100 ℃, ball-milling for 2-3 h, placing the mixed gel in a sintering furnace, heating to 650-800 ℃, and preserving heat for 2-3 h to obtain MgO-Al2O3-CaO glass powder.

The above-mentioned alpha-Al₂O₃The particle size of the micro powder is 3-5 mu m; the average particle diameter of the gamma-alumina is 0.25 μm; the MgO-Al₂O₃The CaO glass powder and the silicon oxide are ground and sieved by a 2000-mesh sieve.

Example 2

The preparation process of the ceramic material for the temperature controller comprises the following steps:

P1.α-Al₂O₃surface modification of the micro powder: 900g of alpha-Al₂O₃Adding the micro powder and 36g of diisopropyl bis (triethanolamine) titanate into 2L of toluene solvent, mixing, stirring for 4h at 90 ℃, filtering, washing and drying to obtain the surface modified alpha-Al₂O₃And (5) micro-powder.

P2.MgO-Al₂O₃Surface modification of CaO glass frits: 30g of MgO-Al₂O₃Adding CaO glass powder and 1.5g of 3- (2, 3-epoxypropoxy) propyl trimethoxy silane into 500mL of toluene solvent, mixing, stirring for 3h at 110 ℃, filtering, washing and drying to obtain silane modified MgO-Al₂O₃CaO glass frit.

P3. premixing: the prepared surface modified alpha-Al₂O₃Fine powder and silane-modified MgO-Al₂O₃And (3) adding CaO glass powder into 5L of toluene solvent, fully and uniformly mixing, then adding 108g of tributylamine, reacting for 4 hours at the temperature of 120 ℃ under the inert atmosphere, performing suction filtration, and performing vacuum drying to obtain a premix.

And P4, mixing materials: and adding the pre-mixture, 50g of gamma-alumina, 20g of silicon oxide, 24g of polyamide wax, 6g of polyethylene wax and 18g of polycarboxylate based polymer FS20 into a high-speed ball mill, grinding for 5 hours at a speed of 360r/min, wherein the dispersion medium is 2kg of deionized water, and the grinding medium is high-purity alumina ceramic balls, and grinding to obtain uniformly mixed slurry.

P5. and granulating: and carrying out spray drying granulation on the slurry to obtain the ceramic granules with the average particle size of 5-20 microns.

And P6, sintering: carrying out cold isostatic pressing on the ceramic granules, wherein the pressure of the cold isostatic pressing is 80MPa, obtaining a ceramic blank, then carrying out surface modification processing on the ceramic blank, placing the ceramic blank in a high-temperature sintering furnace, carrying out pressureless sintering in an inert atmosphere, and carrying out the pressureless sintering in three sections: heating to 700 deg.C at a rate of 5 deg.C/min, and maintaining for 45 min; then heating to 1000 ℃ at the speed of 10 ℃/min, and preserving heat for 30 min; then the temperature is raised to 1200 ℃ at the speed of 3 ℃/min, and the temperature is kept for 2 h. And then heating to 1300 ℃, preserving the temperature for 20min, and naturally cooling to obtain the ceramic material of the temperature controller.

The above-mentioned MgO-Al₂O₃CaO glass frit was prepared in the same manner as in compositional example 1, except that 256g of magnesium nitrate hexahydrate, 81.6g of calcium acetate and 15.8g of aluminum isopropoxide were used.

The above-mentioned alpha-Al₂O₃The particle size of the micro powder is 3-5 mu m; the average particle diameter of the gamma-alumina is 1 μm; the MgO-Al₂O₃The CaO glass powder and the silicon oxide are ground and sieved by a 2000-mesh sieve.

Example 3

The preparation process of the ceramic material for the temperature controller comprises the following steps:

P1.α-Al₂O₃surface modification of the micro powder: 850g of alpha-Al₂O₃Adding the micro powder and 25g of diisopropyl bis (triethanolamine) titanate into 2L of toluene solvent, mixing, stirring for 5h at 85 ℃, filtering, washing and drying to obtain the surface modified alpha-Al₂O₃And (5) micro-powder.

P2.MgO-Al₂O₃Surface modification of CaO glass frits: 40g of MgO-Al₂O₃Adding CaO glass powder and 2.4g of 3- (2, 3-epoxypropoxy) propyl trimethoxy silane into 500mL of toluene solvent, mixing, stirring for 4h at 100 ℃, filtering, washing and drying to obtain silane modified MgO-Al₂O₃CaO glass frit.

P3. premixing: the prepared surface modified alpha-Al₂O₃Fine powder and silane-modified MgO-Al₂O₃And adding CaO glass powder into 5L of toluene solvent, fully and uniformly mixing, then adding 85g of tributylamine, reacting for 5 hours at the temperature of 110 ℃ under the inert atmosphere, performing suction filtration, and performing vacuum drying to obtain a premix.

And P4, mixing materials: and adding the pre-mixture, 70g of gamma-alumina, 40g of silicon oxide, 20g of polyamide wax, 5g of polyethylene wax and 15g of polycarboxylate based polymer FS20 into a high-speed ball mill, grinding for 5 hours at a speed of 420r/min, wherein the dispersion medium is 2kg of deionized water, and the grinding medium is high-purity alumina ceramic balls, and grinding to obtain uniformly mixed slurry.

P5. and granulating: and carrying out spray drying granulation on the slurry to obtain the ceramic granules with the average particle size of 5-20 microns.

And P6, sintering: carrying out cold isostatic pressing on the ceramic granules, wherein the pressure of the cold isostatic pressing is 80MPa, obtaining a ceramic blank, then carrying out surface modification processing on the ceramic blank, placing the ceramic blank in a high-temperature sintering furnace, carrying out pressureless sintering in an inert atmosphere, and carrying out the pressureless sintering in three sections: heating to 700 deg.C at a rate of 5 deg.C/min, and maintaining for 45 min; then heating to 1000 ℃ at the speed of 10 ℃/min, and preserving heat for 30 min; then the temperature is raised to 1100 ℃ at the speed of 5 ℃/min, and the temperature is preserved for 3 h. And then heating to 1300 ℃, preserving the temperature for 30min, and naturally cooling to obtain the ceramic material of the temperature controller.

The above-mentioned MgO-Al₂O₃CaO glass frit was prepared in the same manner as in compositional example 1, except that 256g of magnesium nitrate hexahydrate, 81.6g of calcium acetate and 31.6g of aluminum isopropoxide were used.

The above-mentioned alpha-Al₂O₃The particle size of the micro powder is 3-5 mu m; the average particle diameter of the gamma-alumina is 1 μm; the MgO-Al₂O₃The CaO glass powder and the silicon oxide are ground and sieved by a 2000-mesh sieve.

Example 4

The preparation process of the ceramic material for the temperature controller comprises the following steps:

P1.α-Al₂O₃surface modification of the micro powder: 836g of alpha-Al₂O₃Adding the micro powder and 21g of diisopropyl bis (triethanolamine) titanate into 2L of toluene solvent, mixing, stirring for 5h at 85 ℃, filtering, washing and drying to obtain the surface modified alpha-Al₂O₃And (5) micro-powder.

P2.MgO-Al₂O₃Surface modification of CaO glass frits: 42g of MgO-Al₂O₃Adding CaO glass powder and 3.2g of 3- (2, 3-epoxypropoxy) propyl trimethoxy silane into 500mL of toluene solvent, mixing, stirring for 4h at 100 ℃, filtering, washing and drying to obtain silane modified MgO-Al₂O₃CaO glass frit.

P3. premixing: the prepared surface modified alpha-Al₂O₃Fine powder and silane-modified MgO-Al₂O₃And (2) adding CaO glass powder into 5L of toluene solvent, fully and uniformly mixing, then adding 96g of tributylamine, reacting for 5 hours at the temperature of 110 ℃ under the inert atmosphere, performing suction filtration, and performing vacuum drying to obtain a premix.

And P4, mixing materials: and (2) adding the pre-mixture, 87g of gamma-alumina, 35g of silicon oxide, 19.5g of polyamide wax, 6.5g of polyethylene wax and 16g of polyethylene glycol-based polymer FS10 into a high-speed ball mill, grinding for 5 hours at a speed of 420r/min, wherein the dispersion medium is 2kg of deionized water, and the grinding medium is high-purity alumina ceramic balls, and grinding to obtain uniformly mixed slurry.

P5. and granulating: and carrying out spray drying granulation on the slurry to obtain the ceramic granules with the average particle size of 5-20 microns.

And P6, sintering: carrying out cold isostatic pressing on the ceramic granules, wherein the pressure of the cold isostatic pressing is 80MPa, obtaining a ceramic blank, then carrying out surface modification processing on the ceramic blank, placing the ceramic blank in a high-temperature sintering furnace, carrying out pressureless sintering in an inert atmosphere, and carrying out the pressureless sintering in three sections: heating to 700 deg.C at a rate of 5 deg.C/min, and maintaining for 45 min; then heating to 1000 ℃ at the speed of 10 ℃/min, and preserving heat for 30 min; then the temperature is raised to 1200 ℃ at the speed of 5 ℃/min, and the temperature is preserved for 3 h. And then heating to 1300 ℃, preserving the temperature for 20min, and naturally cooling to obtain the ceramic material of the temperature controller.

The above-mentioned MgO-Al₂O₃CaO glass frit was prepared in the same manner as in compositional example 1, except that 256g of magnesium nitrate hexahydrate, 61.2g of calcium acetate and 15.8g of aluminum isopropoxide were used.

The above-mentioned alpha-Al₂O₃The particle size of the micro powder is 3-5 mu m; the average particle diameter of the gamma-alumina is 1 μm; the MgO-Al₂O₃The CaO glass powder and the silicon oxide are ground and sieved by a 2000-mesh sieve.

Comparative example 1

The preparation method of the ceramic material in the comparative example comprises the following steps: 950g of alpha-Al₂O₃Fine powder, 30g of MgO-Al₂O₃Adding CaO glass powder, 20g of silicon oxide, 30g of polyethylene wax and 20g of sodium hexametaphosphate into a high-speed ball mill, grinding for 5 hours at the speed of 450r/min, wherein a dispersion medium is 2kg of deionized water, a grinding medium is high-purity alumina ceramic balls, and grinding to obtain uniformly mixed slurry.

And then carrying out spray drying granulation on the slurry to obtain ceramic granules with the average particle size of 5-20 microns, carrying out cold isostatic pressing on the ceramic granules to obtain a ceramic blank, carrying out surface modification on the ceramic blank, placing the ceramic blank in a high-temperature sintering furnace, heating to 1400 ℃ under an inert atmosphere, and carrying out heat preservation for 8 hours to obtain the ceramic material.

Comparative example 2

The preparation method of the ceramic material in the comparative example comprises the following steps: 950g of alpha-Al₂O₃Adding the micro powder, 20g of MgO, 10g of CaO, 20g of silicon oxide, 30g of polyethylene wax and 20g of sodium hexametaphosphate into a high-speed ball mill, grinding for 5 hours at the speed of 450r/min, wherein the dispersion medium is 2kg of deionized water, and the grinding medium is high-purity alumina ceramic balls, and grinding to obtain uniformly mixed slurry.

And then carrying out spray drying granulation on the slurry to obtain ceramic granules with the average particle size of 5-20 microns, carrying out cold isostatic pressing on the ceramic granules to obtain a ceramic blank, carrying out surface modification on the ceramic blank, placing the ceramic blank in a high-temperature sintering furnace, heating to 1450 ℃ in an inert atmosphere, and carrying out heat preservation for 7 hours to obtain the ceramic material.

The ceramic materials prepared in the above examples 1 to 4 and comparative examples 1 to 2 were tested for bulk density, tensile strength, flexural strength, fracture toughness, compressive strength, insulation and thermal conductivity, and the test results are shown in the following table 1 and the test methods are shown below.

The bulk density was determined according to GB/T5593-1999;

the tensile strength was measured according to GB/T23805-2009;

flexural strength was measured according to GB/T4741-1999;

fracture toughness was determined according to GB/T23806-;

the compressive strength was measured according to GB/T4740-1999;

the volume resistivity was measured according to GB/T5593-1999;

the thermal conductivity test method comprises the following steps: the thermal diffusion coefficient of the sample after grinding and polishing is measured by a thermal analyzer, and then the thermal diffusion coefficient is measured by a formula of lambda ═ alpha · rho · CP, wherein lambda is thermal conductivity, alpha is thermal diffusion coefficient, rho is sample density, and CP is sample specific heat measured by an archimedes method.

TABLE 1 ceramic material Performance test results

From the results of the comparative tests of the above examples 1 to 4, it can be seen that the ceramics of the present invention have excellent mechanical properties, lower thermal conductivity, higher compressive strength and volume resistivity. The invention adds MgO-Al₂O₃The material disclosed by the invention has the advantages that the compressive strength and the fracture toughness of the material are obviously improved, the compactness is improved, the thermal conductivity is reduced, and the material is suitable for a ceramic shell or a support body of a temperature controller.

The technical features of the embodiments described above can be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention.