阅读说明：本技术 一种陶瓷表面金属化工艺 (Ceramic surface metallization process ) 是由 包信海 张翰中 包信章 于 2019-08-26 设计创作，主要内容包括：本发明提供了一种陶瓷表面金属化工艺,包括如下步骤：通过等静压成型技术制备预烧坯体；预烧结,将装有所述预烧坯体的坩埚置于800-900℃烧结炉内进行低温烧结得第一陶瓷坯体；加工,对第一陶瓷坯体进行机械加工控制尺寸精度,得第二陶瓷坯体；涂金属化层,往所述第二陶瓷坯体表面涂覆金属化涂料得第三陶瓷坯体；以及完全烧结,将第三陶瓷坯体置于1200-1350℃烧结炉内烧结完成陶瓷表面金属化工艺。所述陶瓷表面金属化工艺克服现有技术的不足,制备方法简单,陶瓷与金属表面结合强度大。(The invention provides a ceramic surface metallization process, which comprises the following steps: preparing a pre-sintering blank body by an isostatic pressing technology; pre-sintering, namely placing the crucible filled with the pre-sintered blank body in a sintering furnace at 800-900 ℃ for low-temperature sintering to obtain a first ceramic blank body; machining, namely machining the first ceramic blank to control the dimensional precision to obtain a second ceramic blank; coating a metallized layer, and coating a metallized coating on the surface of the second ceramic blank to obtain a third ceramic blank; and completely sintering, namely placing the third ceramic blank body in a sintering furnace at 1200-1350 ℃ to sinter to finish the ceramic surface metallization process. The ceramic surface metallization process overcomes the defects of the prior art, the preparation method is simple, and the bonding strength of the ceramic and the metal surface is high.)

1. A ceramic surface metallization process is characterized by comprising the following steps:

Preparing a pre-sintering blank body by an isostatic pressing technology;

Pre-sintering, namely placing the crucible filled with the pre-sintered blank body in a sintering furnace at 800-900 ℃ for low-temperature sintering to obtain a first ceramic blank body;

Machining, namely machining the first ceramic blank to control the dimensional precision to obtain a second ceramic blank;

Coating a metallized coating on the surface of the second ceramic blank to obtain a third ceramic blank; and

And (4) completely sintering, namely placing the third ceramic blank body in a sintering furnace at 1200-1350 ℃ to sinter to finish the ceramic surface metallization process.

2. the ceramic surface metallization process according to claim 1, wherein the pre ~ sintering temperature rise speed is 5 ~ 8 ℃/min, and the heat preservation is carried out for 8 ~ 9 h.

3. The process of claim 2, wherein the metallized coating is prepared by mixing a metal powder, a solvent, and a thixotropic agent.

4. the ceramic surface metallization process according to claim 3, wherein the metal powder is at least one of silver powder, molybdenum powder, copper powder, manganese powder, titanium powder, iron powder, nickel powder and chromium powder, and the particle size of the metal powder is 5um ~ 100 um.

5. The ceramic surface metallization process of claim 4, wherein the solvent is an organic solvent.

6. The process of claim 5, wherein the thixotropic agent is at least one of sphingomyelin, phosphatidylserine, phosphatidylglycerol, soy lecithin, diphosphatidylglycerol, phosphatidylinositol, or cephalin.

7. The process of claim 6, wherein the metallization coating is applied to the surface of the second ceramic body by screen printing, pad printing, spraying, or pen coating.

8. The ceramic surface metallization process of claim 7, wherein the full sintering of the third ceramic body is performed under a hydrogen reducing atmosphere.

9. the ceramic surface metallization process according to claim 8, wherein the temperature rise rate of the full sintering is 5 ~ 8 ℃/min, and the temperature is kept for 8 ~ 9 h.

10. the process of claim 8, wherein the thickness of the metallized layer on the surface of the ceramic is 10-100 um.

Technical Field

The invention relates to the technical field of metal ceramics, in particular to a ceramic surface metallization process.

Background

Zirconium oxide (ZrO)₂) The material is an excellent non-metallic material, and has the characteristics of high hardness, high toughness, low thermal conductivity, wear resistance, corrosion resistance, high-temperature conductivity and the like. In recent years, with the intensive research and development and utilization of ceramic materials, the research and development and application of zirconia ceramic materials in the aspects of special ceramics such as electronic ceramics, functional ceramics and structural ceramics are rapidly developed, and the special ceramic materials become basic materials of aerospace, aviation, electronics and nuclear industries and are in high and new technology fieldsThe application is abnormally active. In addition, zirconia plays an important role in the development of electronics and new material industries, is continuously applied to the departments of metallurgy, chemical engineering, glass, medicine and the like, and has wide application prospects.

When the zirconia ceramic substrate is used as an LED heat dissipation substrate, a ceramic package and an electronic circuit substrate, in order to establish the connection between a semiconductor device or an IC chip on the zirconia ceramic substrate and an external system and transmit electric energy and signals for an internal device or a chip, the zirconia ceramic and metal need to be welded. However, since the surface structure of the ceramic material is different from that of the metal material, the welding often cannot wet the surface of the ceramic material and cannot act on the surface of the ceramic material to form firm adhesion, so that a special sealing process of the ceramic and the metal, namely a method for metalizing the surface of the ceramic, needs to be adopted. The surface metallization of the zirconia ceramics means that a layer of metal film with high conductivity and firm combination is coated on the surface of a working part of the zirconia ceramics so as to realize the welding between ceramics and metals. The existing surface metallization method of zirconia ceramics mainly comprises a molybdenum-manganese method, a gold plating method, a copper plating method, a tin plating method, a nickel plating method, a LAP method (metal plating after laser) and other ceramic surface metallization processes, and the main process is as follows: the ceramic surface is metallized and sintered → the metal film is deposited → the solder is heated to seal the ceramic and the metal. In these methods, the treatment steps are numerous, which makes the process complicated and has many factors affecting the surface of the zirconia ceramic metal, which is not favorable for obtaining the high quality zirconia ceramic metal surface.

The invention patent with the publication number of CN109422547A specifically discloses a method for metallizing the surface of zirconia ceramics, which comprises the following steps: A. cleaning the surface of the zirconia ceramic; B. coating a protective agent on a selected position of the zirconia ceramic, and curing; C. activating the surface of the zirconia ceramic; D. putting the zirconia ceramic into a vacuum chamber, and irradiating the surface of the zirconia ceramic by using an electron beam to realize the metallization of the surface of the zirconia ceramic. The invention can improve the defects of the prior art, and the produced zirconia ceramic has high metalized surface quality and strong controllability.

The above patent adopts an electron beam irradiation method to realize the metallization of the surface of the zirconia ceramic, and has complex preparation process and larger energy consumption.

Disclosure of Invention

The technical problem to be solved by the invention is to overcome the defects of the prior art and provide a ceramic surface metallization process, which has the advantages of simple preparation method and high bonding strength between the ceramic and the metal surface.

In order to achieve the above purpose, the invention adopts a technical scheme that:

A ceramic surface metallization process comprises the following steps: preparing a pre-sintering blank body by an isostatic pressing technology; pre-sintering, namely placing the crucible filled with the pre-sintered blank body in a sintering furnace at 800-900 ℃ for low-temperature sintering to obtain a first ceramic blank body; machining, namely machining the first ceramic blank to control the dimensional precision to obtain a second ceramic blank; coating a metallized coating on the surface of the second ceramic blank to obtain a third ceramic blank; and completely sintering, namely placing the third ceramic blank body in a sintering furnace at 1200-1350 ℃ to sinter to finish the ceramic surface metallization process.

further, the temperature rising speed of the pre ~ sintering is 5 ~ 8 ℃/min, and the heat preservation is carried out for 8 ~ 9 h.

Further, the metallized coating is prepared by mixing metal powder, a solvent and a thixotropic agent.

further, the metal powder is at least one of silver powder, molybdenum powder, copper powder, manganese powder, titanium powder, iron powder, nickel powder and chromium powder, and the particle size of the metal powder is 5um ~ 100 um.

Further, the solvent is an organic solvent.

Further, the thixotropic agent is at least one of sphingomyelin, phosphatidylserine, phosphatidylglycerol, soybean lecithin, diphosphatidylglycerol, phosphatidylinositol or cephalin.

Further, the metallization coating is coated on the surface of the second ceramic blank body in a screen printing mode, a transfer printing mode, a spraying mode or a pen coating mode.

Further, the complete sintering of the third ceramic body is performed under the protection of hydrogen reducing atmosphere.

further, the temperature rising speed of the complete sintering is 5 ~ 8 ℃/min, and the temperature is kept for 8 ~ 9 h.

furthermore, the thickness of the prepared ceramic surface metallization layer is 10um ~ 100 um.

Compared with the prior art, the technical scheme of the invention has the following advantages:

(1) according to the ceramic surface metallization process, the surface of the second ceramic blank is coated with the metallization layer, the metal powder can penetrate into the air holes on the outer surface of the second ceramic blank which is not completely burnt, and the ceramic surface metallization layer is tightly combined with the ceramic material after the second ceramic blank is completely sintered. The ceramic surface metal layer is formed in the sintering and forming process of the ceramic material, the process is simple, the operation is easy, and a large amount of energy is not required to be additionally consumed.

(2) According to the ceramic surface metallization process, after pre-sintering, ceramic particles are mutually aggregated, partial air holes are filled, and sintering necks are formed, so that the first ceramic blank has certain strength and hardness, but the strength is not very high, the ceramic blank can be processed by a common machining technology, and the influence on the bonding performance of a metal layer and the ceramic surface due to the fact that the ceramic surface is processed after complete sintering is avoided. The size precision is improved, and the cost of processing equipment is reduced.

(3) According to the ceramic surface metallization process, the thixotropic agent is added into the metallization coating, so that the consistency of the metallization coating is reduced under the action of shearing force such as stirring or blade coating, the metallization coating is beneficial to coating, the viscosity of the metallization coating is increased when the metallization coating is not subjected to the action of the shearing force, and the metallization coating is beneficial to curing at a fixed position. The thixotropic agent has the function of reducing or inhibiting the surface tension of the metallized coating, so that the metallized coating does not have the phenomenon of unevenness in the drying process, the metallized layer can be uniformly attached to the surface of the second ceramic blank, the welding defects of insufficient solder, air holes and the like during the welding of ceramic and metal are avoided, the contact surface of the ceramic and a metal piece during the packaging is improved, the binding force is enhanced, and the packaging reliability is improved.

(4) According to the ceramic surface metallization process, the third ceramic body is completely sintered under the protection of the hydrogen reducing atmosphere, so that the oxidation of the ceramic surface metallization layer is prevented, and the reliability of subsequent welding is improved.

drawings

The technical solution and the advantages of the present invention will be apparent from the following detailed description of the embodiments of the present invention with reference to the accompanying drawings.

FIG. 1 is a flow chart of a metallization process for ceramic surfaces according to the present invention.

Detailed Description

the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the 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.

In this embodiment, a process for metallizing a ceramic surface is provided, as shown in fig. 1, including the following steps:

S10, preparing a pre-sintered blank by an isostatic pressing technology; s20, pre-sintering, namely placing the crucible filled with the pre-sintered blank body in a sintering furnace at 800-900 ℃ for low-temperature sintering to obtain a first ceramic blank body; s30, machining the first ceramic blank to control the size precision, and obtaining a second ceramic blank; s40, coating a metallized coating on the surface of the second ceramic blank to obtain a third ceramic blank; and S50, sintering completely, and sintering the third ceramic blank in a sintering furnace at 1200-1350 ℃ to complete the ceramic surface metallization process.

s10 preparing the pre-sintered blank body by an isostatic pressing technology. The zirconia ceramic has excellent performances of high temperature resistance, corrosion resistance, good toughness, small specific heat capacity, small heat conductivity and the like, has excellent effects when being applied to industries such as machinery, metallurgy, chemical industry, textile, aerospace, biology, electronics and the like, and the ceramic powder selected by the embodiment is 3mol% of Y₂O₃The grain size of the doped tetragonal zirconia powder is 30-1000nm, and the specific surface area of the ceramic powder is 30-60m²The particle size distribution conforms to the normal distribution curve. The zirconiaThe ceramic powder is subjected to a spray granulation process before use so as to have good fluidity. And (3) loading the ceramic powder into a special mould in a vibration charging mode, and wrapping and coating the ceramic powder on the outer surface of the mould by using a winding film to seal the mould after charging.

And placing the assembled die in a hydraulic cylinder of a cold isostatic press for isostatic pressing, wherein the cold isostatic pressing pressure is 180-260MPa, and the pressure maintaining time is 30-120 s. The isostatic compaction is that a sample to be pressed is placed in a hydraulic cylinder, the sample is uniformly pressurized from all directions by utilizing the incompressible property and the uniform pressure transmission property of a liquid medium, and when the liquid medium is injected into the hydraulic cylinder through a pressure pump, the pressure intensity of the liquid medium is invariable and uniformly transmitted to all directions according to the fluid mechanics principle. The powder in the hydraulic cylinder is uniformly and uniformly stressed in all directions. The pressure transmitted by the liquid medium during isostatic pressing is equal in all directions. The deformation of the elastic die generated when the elastic die is under the pressure of the liquid medium is transferred to the powder in the die, the friction force between the powder and the die wall is small, the blank body is stressed uniformly, the density distribution is uniform, and the product performance is greatly improved. The isostatic pressing process has the outstanding advantages of uniform tissue structure, high density, small sintering shrinkage, low mold cost, high production efficiency, capability of forming slender products, large-size products, precise-size products and the like with complex shapes. The hydraulic medium that cold isostatic pressing chooseed for use can be water or hydraulic oil, and the hydraulic medium is hydraulic oil for this embodiment chooses for use to prevent to use water pressure and make water get into the mould through the gap of mould seam department and influence shaping effect and yield. The relative density of the prepared pre-sintering blank body is gradually increased along with the increase of the forming pressure in the hydraulic cylinder, and the forming pressure can be any one of 180 MPa, 190MPa, 200MPa, 210MPa, 220MPa, 230MPa, 240MPa, 250MPa and 260 MPa. The influence of the molding pressure on the relative density of the pre-sintered blank body is related to the property of the powder body, different ceramic powder bodies have critical pressure, and when the pressure reaches a certain value, the relative density of the pre-sintered blank body does not change greatly along with the increase of the selected molding pressure. The critical forming pressure of the zirconia ceramics is 200-230 MPa. The dwell time is 30-120s, preferably 50s, 60s, 70s, 80s, 90s, 100s or 110s, the dwell time has indirect influence on the performance of the material, the generation of microcracks in the presintering blank with rapid pressure relief can be effectively prevented, and the problems of uneven strength, microcracks and the like of the presintering blank can be effectively prevented by maintaining a certain forming pressure.

Taking the mould after isostatic pressing treatment out of the hydraulic cylinder, washing to remove oil stains on the surface of the mould, preventing the oil stains from influencing the surface quality of the pre-sintered blank, placing the pre-sintered blank in a crucible, generally stacking the pre-sintered blank in the crucible for sintering in order to more efficiently utilize energy in batch production, generally brushing a layer of stabilizing agent serving as anti-sticking powder between the pre-sintered blanks to prevent the pre-sintered blanks from being stuck in the process of re-sintering, wherein the stabilizing agent can be CeO₂Or Y₂O₃In this embodiment, Y is preferred₂O₃And (3) powder.

S20 pre ~ sintering, placing the crucible containing the pre ~ sintered blank body in a sintering furnace at 800 ~ 900 ℃ for low ~ temperature sintering to obtain a first ceramic blank body, sintering the pre ~ sintered blank body, wherein the sintering temperature can be any one of 800 ℃, 820 ℃, 850 ℃, 855 ℃, 860 ℃, 865 ℃, 870 ℃, 875 ℃, 880 ℃, 885 ℃, 890 ℃, 895 ℃ and 900 ℃ or any one of 850 ~ 900 ℃, the heating speed is 5 ~ 8 ℃/min, and the heat preservation is carried out for 8 ~ 9h³. The Vickers hardness is between 1.0 and 1.2GPa, and the first ceramic body has certain strength.

TABLE 1 influence of different sintering temperatures on the density and hardness of the first ceramic body

Sintering temperature (. degree. C.)	Density (g/cm)3）	vickers hardness (GPa)
			800	3.02±0.08	0.09±0.02
850	3.14±0.05	1.1±0.03
			900	3.23±0.06	1.2±0.03

And S30, machining the first ceramic blank to control the size precision, and obtaining a second ceramic blank. After the pre-sintering, the hardness of the first ceramic blank body is not in a fully sintered state, and the first ceramic blank body can be processed by using common machining equipment, wherein the main processing method comprises the processing processes of turning, polishing and the like. The method avoids using diamond processing equipment and special processing equipment for ceramics, can process by using common processing equipment, greatly reduces the investment of the processing equipment, controls the size precision of the first ceramic blank body through mechanical processing, and obtains a second ceramic blank body with more precise size.

S40, coating a metallized layer, washing a second ceramic blank, removing dust in pores on the outer surface of the second ceramic blank by using ultrasonic cleaning equipment, coating a metallized coating on the surface of the second ceramic blank to obtain a third ceramic blank, wherein the metallized coating is prepared by mixing metal powder, a solvent and a thixotropic agent, the metal powder is at least one of silver powder, molybdenum powder, copper powder, manganese powder, titanium powder, iron powder, nickel powder and chromium powder, the particle size of the metal powder is 5um ~ 100 um., the solvent is an organic solvent, and the solvent can be at least one of terpineol, diethylene glycol ether acetate, tributyl citrate or tributyl phthalate, the thixotropic agent is at least one of sphingomyelin, phosphatidylserine, phosphatidylglycerol, soybean lecithin, diphosphatidylglycerol, phosphatidylinositol or cephalin, the metallized coating is coated on the surface of the second ceramic blank by screen printing, transfer printing, spraying or pen coating, and the like.

S50, sintering the third ceramic blank in a sintering furnace at 1200 ~ 1350 ℃ to complete the ceramic surface metallization process, wherein the complete sintering process is carried out under the protection of hydrogen reducing atmosphere to prevent the oxidation of the metal layer in the sintering process to influence the subsequent welding bonding strength, any one of the sintering temperatures of 1200 ℃, 1215 ℃, 1230 ℃, 1250 ℃, 1265 ℃, 1280 ℃, 1300 ℃, 1330 ℃ and 1350 ℃ or any one of the temperature values of 1200 ~ 1350 ℃ can be selected according to the performance requirements of the powder body and the final ceramic cover plate, the heating speed is 5 ~ 8 ℃/min, preferably any one of the heating speed values of 5 ℃/min, 6 ℃/min, 7 ℃/min and 8 ℃/min, the slow heating speed can prevent the occurrence of microcracks in the rapid heating material, the heat preservation time is 8 ~ 9h, preferably any one of 8h, 8.5h and 9h, and the longer heat preservation time can provide enough time for the complete sintering of the ceramic, so as to prevent the problems of the breakage, insufficient toughness and the like of the later ~ stage material caused by incomplete sintering.

The ceramic surface metal layer prepared by the process has excellent thermal shock resistance and strong bonding force with the ceramic matrix. And the thickness of the metal layer formed on the surface of the ceramic can be adjusted according to the viscosity of the metalized coating, and the thickness of the metal layer on the surface of the ceramic can reach 100 um. The formed metal layer has good welding performance.

the above description is only an exemplary embodiment of the present invention, and not intended to limit the scope of the present invention, and all equivalent structures or equivalent processes that are transformed by the content of the present specification and the attached drawings, or directly or indirectly applied to other related technical fields, are included in the scope of the present invention.