Method for improving bonding strength of coating and ceramic

Abstract

The invention discloses a method for improving the bonding strength of a coating and ceramic, and belongs to the technical field of functional coatings, and the method comprises the following steps: S1, preparing an aluminum nitride ceramic substrate with the surface flatness TTV less than or equal to 20 microns and the thermal conductivity greater than 150 W / m.K; s2, the surface of the aluminum nitride ceramic substrate is subjected to sand blasting treatment, and the surface roughness is obtained to enhance the mechanical interlocking force; s3, a thermal spraying method is adopted, yttrium oxide powder is used for spraying, and a yttrium oxide ceramic coating is deposited on the surface of the aluminum nitride ceramic substrate; and S4, the sprayed aluminum nitride ceramic substrate is placed in a closed heat treatment furnace to be subjected to heat treatment, and the coating structure with the bonding strength remarkably improved is obtained after cooling. And S5, post-processing the aluminum nitride ceramic substrate subjected to heat treatment to obtain a target thickness and a target shape. According to the method, interface reaction, recrystallization and stress release of the coating are induced through heat treatment, the bonding strength is remarkably improved, and the interface heat stability is also enhanced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of functional coating, in particular to a method for improving the bonding strength of coating and ceramic. BACKGROUND

[0002] In the semiconductor industry, aluminum nitride (AlN) is widely used for electrical insulation and heat sink components due to its excellent thermal conductivity, low dielectric constant, and good insulation performance. In order to enhance its durability in corrosive process atmospheres (such as CF4, O2, Cl2, etc.), there is a need to coat a high-purity yttrium oxide (Y2O3) ceramic layer on the surface of AlN.

[0003] Yttrium oxide has strong resistance to fluorine plasma corrosion, but the coating formed by thermal spraying deposition has defects such as stress concentration, micro-cracks, and pores between the interface of the coating and the aluminum nitride substrate, and the bonding strength is usually insufficient. Especially under high temperature and thermal shock conditions, failure behaviors such as coating peeling and interface peeling easily occur, which limits its popularization and application in high-end equipment.

[0004] In the prior art, transition layers (such as YAG, YSZ) or surface laser remelting are introduced to improve the bonding performance, but there are problems such as complex process, pollution risk, or poor material compatibility, and it is not easy to realize industrialization. SUMMARY

[0005] The technical problem to be solved by the present application is to provide a method for improving the bonding strength of coating and ceramic to solve the problems raised in the background.

[0006] In order to solve the above technical problems, the technical scheme of the present application is as follows:

[0007] A method for improving the bonding strength of coating and ceramic, the method comprising the following steps:

[0008] S1: preparing an aluminum nitride ceramic substrate with a surface flatness TTV≤20μm and a thermal conductivity greater than 150W / m·K;

[0009] S2: sandblasting the surface of the above-mentioned aluminum nitride ceramic substrate to obtain a surface roughness to enhance the mechanical interlocking force;

[0010] S3: using a thermal spraying method, using yttrium oxide powder to spray and deposit a layer of yttrium oxide ceramic coating on the surface of the aluminum nitride ceramic substrate;

[0011] S4: placing the sprayed aluminum nitride ceramic substrate in a sealed heat treatment furnace for heat treatment, and obtaining a coating structure with significantly improved bonding strength after cooling; the bonding strength of the coating is tested by the ASTM C633 method.

[0012] S5: post-processing the yttria ceramic coating on the aluminum nitride ceramic substrate after heat treatment to obtain a target thickness and a target morphology.

[0013] Preferably, in the step S2, the sandblasting material used for sandblasting treatment is high-purity alumina sand with a particle size of #80-#220, and the sandblasting pressure is 0.4-0.8 MPa. After sandblasting treatment, the surface roughness Ra of the aluminum nitride ceramic substrate is 3-5 μm.

[0014] Preferably, in the step S3, the thermal spraying method is atmospheric plasma spraying (APS) or suspension plasma spraying (SPS), the spraying power of thermal spraying is 30-40 kW, the powder feeding rate is 5-40 g / min, the spraying distance is 90-250 mm, and the thickness of the yttria ceramic coating is 10-200 μm.

[0015] Preferably, in the step S3, the purity of the yttria powder is not less than 99.9%, and the particle size is 5-20 μm.

[0016] Preferably, in the step S4, the heat treatment temperature is 400-800℃, the holding time is 0.5-3 hours, the heating rate is less than 5℃ / min, and the cooling is slow.

[0017] Preferably, the heat treatment atmosphere is argon, nitrogen or vacuum, the furnace pressure ranges from 1×10-2 Pa to normal pressure, and the cooling mode is furnace cooling or natural cooling.

[0018] The above technical solution has the following beneficial effects:

[0019] The method of the present application induces coating interface reaction, recrystallization and stress release through heat treatment, which not only significantly improves the bonding strength, but also enhances the interface thermal stability. The process does not need to introduce an additional transition layer, is simple to operate and has no pollution risk. It can be adapted to industrial plasma spraying equipment and is suitable for batch production and application. The resulting structural parts have a longer service life under high-temperature, high-corrosion plasma working conditions. DETAILED DESCRIPTION

[0020] The specific embodiments of the present application are further described below. It should be noted that the description of these embodiments is used to help understand the present application, but does not constitute a limitation on the present application. In addition, the technical features involved in the various embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0021] A method for improving the bonding strength of a coating and a ceramic, comprising the following steps:

[0022] S1: Prepare an aluminum nitride ceramic substrate, the surface flatness TTV is less than or equal to 20 microns, and the thermal conductivity is greater than 150 W / m·K. Specifically, the shape of the aluminum nitride ceramic substrate can be a disc, the aluminum nitride in the aluminum nitride ceramic substrate is more than 98%, the surface flatness TTV is less than or equal to 20 microns, such as 18 microns, and the thermal conductivity is greater than 150 W / m·K, such as 160 W / m·K;

[0023] S2: Perform sandblasting treatment on the surface of the aluminum nitride ceramic substrate to obtain a surface roughness to enhance the mechanical interlocking force;

[0024] Specifically, the surface of the side of the aluminum nitride ceramic substrate that needs to be sprayed is subjected to sandblasting treatment to obtain a surface roughness to enhance the mechanical interlocking force. The sandblasting material used in the sandblasting treatment is high-purity alumina sand, the particle size is #80-#220, the particle size can be specifically #80 or #220, the sandblasting pressure is 0.4-0.8 MPa, the sandblasting pressure can be specifically 0.4 MPa or 0.8 MPa, and the surface roughness Ra of the aluminum nitride ceramic substrate after sandblasting treatment is 3-5 microns, the surface roughness Ra can be specifically 3 microns or 5 microns, or 4 microns;

[0025] S3: Use a thermal spraying method to spray yttrium oxide powder on the surface of the aluminum nitride ceramic substrate to deposit a yttrium oxide ceramic coating;

[0026] Specifically, the thermal spraying method is atmospheric plasma spraying (APS) or suspension plasma spraying (SPS), the spraying power of the thermal spraying is 30-40 kW, the power can be specifically 30 kW or 40 kW, the powder feeding rate is 5-40 g / min, the powder feeding rate can be specifically 5 g / min or 40 g / min, or 20 g / min, the spraying distance is 90-250 mm, the thickness of the yttrium oxide ceramic coating is 10-200 microns, the thickness of the yttrium oxide ceramic coating can be specifically 10 microns or 200 microns, or 100 microns; the purity of the yttrium oxide powder used in the thermal spraying is not less than 99.9%, specifically 99.99%, the particle size is 5-20 microns, and the particle size of the yttrium oxide powder can be specifically 5 microns or 20 microns, or 15 microns;

[0027] S4: Place the sprayed aluminum nitride ceramic substrate in a sealed heat treatment furnace for heat treatment, and obtain a coating structure with significantly improved bonding strength after cooling. The bonding strength of the coating is tested by the ASTM C633 method;

[0028] Specifically, the heat treatment temperature is 400-800℃, the holding time is 0.5-3 hours, the heating rate is less than 5℃ / min, slow cooling, in the heat treatment furnace, the temperature is raised to 400℃ or 800℃ at a heating rate of 4℃ / min, or the temperature can be raised to 600℃ at a heating rate of 4℃ / min, then holding for 0.5 hours or 3 hours, or holding for 1.5 hours, and finally slow cooling to room temperature to complete the heat treatment, wherein the heat treatment atmosphere is argon, nitrogen or vacuum, the furnace pressure ranges from 1×10-2Pa to normal pressure, and the cooling method is furnace cooling or natural cooling. During the heat treatment process, the furnace pressure can be set to 1×10-2Pa, and during the cooling process, it changes to normal pressure. After cooling, the coating bonding strength is tested by the ASTM C633 method.

[0029] S5: Post-processing the yttria ceramic coated aluminum nitride ceramic substrate after heat treatment to obtain a target thickness and a target morphology.

[0030] The method of the present application induces coating interface reaction, recrystallization and stress release through heat treatment, not only significantly improves the bonding strength, but also enhances the thermal stability of the interface; the process does not need to introduce additional transition layer, is simple to operate and has no pollution risk; can be adapted to industrial plasma spraying equipment, suitable for mass production application; the obtained structural parts have longer service life under high temperature, high corrosive plasma working conditions.

[0031] Example 1

[0032] A method for improving the bonding strength of a coating and a ceramic, comprising the following steps:

[0033] Step one: prepare an AlN ceramic substrate with a size of 100×100×30mm, sandblast the substrate with #80 alumina sand to obtain an AlN ceramic substrate with a surface roughness Ra of 4.2μm;

[0034] Step two: select Y2O3 powder with a particle size of 15μm and a purity of 99.99%, deposit the coating in an atmospheric plasma spraying (APS) system, the atmospheric plasma spraying power is 36kW, the powder feeding rate is 12g / min, the spraying distance is 100mm, and the gun speed is 500mm / s;

[0035] Step three: spray to form a coating with a thickness of 200μm, and the surface roughness is 4.7μm;

[0036] Step four: heat treat the coating at 400℃, 500℃, 600℃, 700℃ and 800℃ for 2 hours in an argon atmosphere, and then naturally cool;

[0037] Step five: test the bonding strength by the ASTM C633 method, and the average bonding strength obtained by the test is shown in Table 1 below;

[0038] Table 1, experimental comparison of the bonding strength of yttria sprayed layers under different heat treatment conditions (unit: MPa):

[0039] Heat treatment temperature (°C) Time (h) Atmosphere Average bonding strength (MPa) Without heat treatment 2 Ar 2.45 400 2 Ar 7.72 500 2 Ar 7.11 600 2 Ar 7.20 700 2 Ar 6.89 800 2 Ar 1.46

[0040] According to Table 1, when the heat treatment temperature is between 400-600℃, the average bonding strength increases with the increase of temperature, when the heat treatment temperature is between 600-800℃, the average bonding strength decreases with the increase of temperature, when the heat treatment temperature is between 400-700℃, the average bonding strength is better than that of the sprayed layer without heat treatment, and when the heat treatment temperature is 800℃, the average bonding strength is lower than that of the sprayed layer without heat treatment, therefore, the higher the heat treatment temperature is not necessarily better, and the heat treatment temperature needs to be selected according to the specific conditions.

[0041] Example 2

[0042] A method for improving the bonding strength of a coating and a ceramic, comprising the following steps:

[0043] Step one: select an aluminum nitride ceramic substrate with a size of 250x250x20mm, a purity of 99%, and a thermal conductivity of 180W / m·K;

[0044] Step two: use #220 alumina sand to sandblast the surface to obtain an aluminum nitride ceramic substrate with a surface Ra of 3.5μm;

[0045] Step three: select high-purity Y2O3 powder with an average particle size of 15μm, and use atmospheric plasma spraying (APS) equipment to deposit a coating, wherein the spraying current is 900A, the voltage is 38V, the thickness is 200μm, and the surface roughness is 4.98μm;

[0046] Step four: after spraying, the sample is placed in a vacuum furnace, the vacuum degree is set to 1x10-2Pa, and the temperature is set to 400℃, 500℃, 600℃, 700℃, and 800℃ respectively for 1 hour, and the furnace is cooled;

[0047] Step five: test the bonding strength using the ASTM C633 method, and the results are shown in Table 2;

[0048] Table 2, experimental comparison of the bonding strength of yttria sprayed layers under different heat treatment conditions (unit: MPa):

[0049] Heat treatment temperature (°C) Time (h) Vacuum degree Average bonding strength (MPa) Without heat treatment 1 1 x 10-2Pa 2.80 400 1 1 x 10-2Pa 10.19 500 1 1 x 10-2Pa 9.17 600 1 1 x 10-2Pa 8.95 700 1 1 x 10-2Pa 8.66 800 1 1 x 10-2Pa 8.13

[0050] According to Table 2, under the premise of setting the vacuum degree to 1x10-2Pa during heat treatment, compared with Table 1, the average bonding strength after heat treatment under the premise of setting the vacuum degree to 1x10-2Pa is higher than the average bonding strength after heat treatment under Ar atmosphere, and the average bonding strength after heat treatment under the premise of setting the vacuum degree to 1x10-2Pa is much higher than the average bonding strength without heat treatment, and when the heat treatment temperature is between 400-800℃, the average bonding strength gradually decreases with the increase of the heat treatment temperature, and according to Table 1, the heat treatment temperature can be selected to be 400-500℃, and the vacuum degree is 1x10-2Pa.

[0051] The embodiments of the present application are described in detail above, but the present application is not limited to the described embodiments. For those skilled in the art, various changes, modifications, replacements and variations of the embodiments can be made without departing from the principles and spirits of the present application, and still fall within the protection scope of the present application.

Claims

1. A method for improving the bonding strength between a coating and ceramic, characterized in that, The method includes the following steps: S1: Prepare an aluminum nitride ceramic substrate with a surface flatness TTV≤20μm and a thermal conductivity greater than 150W / m·K; S2: The surface of the above aluminum nitride ceramic substrate is sandblasted to obtain surface roughness to enhance mechanical interlocking force; S3: A layer of yttrium oxide ceramic coating is deposited on the surface of an aluminum nitride ceramic substrate by using a thermal spraying method and yttrium oxide powder spraying. S4: The sprayed aluminum nitride ceramic substrate is placed in a closed heat treatment furnace for heat treatment. After cooling, a coating structure with significantly improved bonding strength is obtained. The bonding strength of the coating is tested using the ASTM C633 method. S5: Post-process the aluminum nitride ceramic substrate with yttrium oxide ceramic coating after heat treatment to obtain the target thickness and target morphology.

2. The method for improving the bonding strength between a coating and ceramic according to claim 1, characterized in that, In step S2, the sandblasting material used is high-purity alumina sand with a particle size of #80 to #220, the sandblasting pressure is 0.4 to 0.8 MPa, and the surface roughness Ra of the aluminum nitride ceramic substrate after sandblasting is 3 to 5 μm.

3. The method for improving the bonding strength between a coating and ceramic according to claim 1, characterized in that, In step S3, the thermal spraying method is atmospheric plasma spraying (APS) or suspended plasma spraying (SPS). The spraying power of the thermal spraying is 30-40kW, the powder feeding rate is 5-40g / min, the spraying distance is 90-250mm, and the thickness of the yttrium oxide ceramic coating is 10-200μm.

4. The method for improving the bonding strength between a coating and ceramic according to claim 1, characterized in that, In step S3, the purity of the yttrium oxide powder is not less than 99.9%, and the particle size is 5-20 μm.

5. The method for improving the bonding strength between a coating and ceramic according to claim 1, characterized in that, In step S4, the heat treatment temperature is 400–800℃, the holding time is 0.5–3 hours, the heating rate is less than 5℃ / min, and the cooling is slow.

6. The method for improving the bonding strength between a coating and ceramic according to claim 5, characterized in that, The heat treatment atmosphere is argon, nitrogen or vacuum, the furnace pressure ranges from 1×10-2 Pa to atmospheric pressure, and the cooling method is furnace cooling or natural cooling.