Yttrium oxide-aluminum oxide composite ceramics with high bonding strength and preparation method and application thereof

Abstract

The invention discloses an yttrium oxide-aluminum oxide composite ceramic with high bonding strength, and a preparation method and application thereof. Aluminum oxide granulated powder and yttrium oxide granulated powder are sequentially added to a forming mold and vibrated and compacted. The filled forming mold is then placed in a cold isostatic press. The powder raw materials in the forming mold are uniformly pressurized by a cold isostatic pressing process, the powder raw materials are compressed in volume, and pores are discharged to obtain a formed ceramic green body with uniform structure and high density. The formed ceramic green body is machine-processed into an yttrium oxide-aluminum oxide composite ceramic green body of a designed shape, and then transferred to a high-temperature sintering furnace for sintering to further improve the strength, thereby obtaining an integrally sintered high-bonding strength yttrium oxide-aluminum oxide composite ceramic. The method solves the problems of poor bonding strength and easy peeling of the yttrium oxide etching-resistant protective coating in the prior art, while strengthening the protective function of the alumina substrate.

Description

Technical Field

[0001] The present invention relates to the technical field of composite ceramic preparation, and in particular to an yttrium oxide-aluminum oxide composite ceramic with high bonding strength, a preparation method and application thereof. Background Art

[0002] Etching is essential in the wafer manufacturing process. When fluorine-containing plasma etches wafers, it inevitably corrodes other alumina ceramic components in the etching atmosphere, reducing their service life. Etching products from other alumina ceramic components can also contaminate the wafer. To address this issue, existing techniques typically apply an etch-resistant coating to the surfaces of the components. Yttrium oxide, due to its excellent plasma tolerance and relatively economical production costs, is widely used in etch-resistant coatings.

[0003] Among them, bonding strength is an important performance indicator of etching-resistant coatings. When the bonding strength of the coating is high, the coating is firmly bonded and not easily detached and ineffective. When the bonding strength of the coating is low, the coating easily falls off the substrate and loses its protective properties. As the plasma power used in the etcher continues to increase, the impact force on the relevant components in the etcher cavity is also gradually increasing, which places increasingly high demands on the bonding strength between the coating and the alumina substrate. Currently, atmospheric plasma spraying is commonly used to prepare yttrium oxide etching-resistant coatings. However, the bonding strength of the yttrium oxide coating prepared by this method to the alumina substrate is poor, and the coating is prone to peeling. Summary of the Invention

[0004] In response to the shortcomings of the prior art, the present invention discloses an yttrium oxide-aluminum oxide composite ceramic with high bonding strength and its preparation method and application, which can solve or at least alleviate one or more of the above-mentioned problems and other problems in the prior art.

[0005] The present invention discloses a method for preparing yttrium oxide-aluminum oxide composite ceramics with high bonding strength, comprising the following steps:

[0006] S1. Powder raw materials are yttrium oxide granulated powder and aluminum oxide granulated powder;

[0007] S2, first adding a certain amount of alumina granulation powder into a forming mold of a cold isostatic press, and vibrating and compacting the alumina granulation powder in the forming mold;

[0008] S3, adding a certain amount of yttrium oxide granulated powder into a forming mold of a cold isostatic press, and vibrating and compacting the yttrium oxide granulated powder in the forming mold;

[0009] S4, repeating steps S2 and S3 n times until the yttrium oxide granulated powder and the aluminum oxide granulated powder fill the entire forming mold; wherein n ≥ 0;

[0010] S5, placing the filled forming mold into a cold isostatic press for cold isostatic pressing;

[0011] S6. Machining the formed ceramic green body in step S5 to obtain at least one yttrium oxide-aluminum oxide composite ceramic green body, and processing the yttrium oxide-aluminum oxide composite ceramic green body into a designed shape, with the alumina portion serving as the alumina substrate and the yttrium oxide portion serving as the coating;

[0012] S7, transferring the yttrium oxide-aluminum oxide composite ceramic green body obtained in step S6 to a high-temperature sintering furnace for sintering, and naturally cooling to room temperature in the furnace to obtain the yttrium oxide-aluminum oxide composite ceramic.

[0013] Preferably, in step S1 , the average particle size of the yttrium oxide granulated powder is 38 μm, and the average particle size of the aluminum oxide granulated powder is 57 μm.

[0014] Preferably, in step S3, positions A and B are respectively provided on the forming mold near its upper and lower ends, and an interface is formed between the alumina granulated powder and the yttrium oxide granulated powder, and the interface is located between positions A and B of the forming mold.

[0015] Preferably, in step S5, the cold isostatic pressing pressure P is 110-130 MPa.

[0016] Preferably, in step S5, the holding time m is 20-50s.

[0017] Preferably, in step S5, the holding time m is 20-30s.

[0018] Preferably, in step S7, the sintering process in the high-temperature sintering furnace includes the following steps:

[0019] S701: heating at a rate of V of 160-240°C / min to 300°C, holding time th; then heating at a rate of V to 400°C, holding time th; then heating at a rate of V to 500°C, holding time th; then heating at a rate of V to sintering temperature T of 1650°C, holding time th; where t is in the range of 1-4h;

[0020] S702: Cooling rate is 2℃ / min, from 1650℃ to 1000℃, and then naturally cooling to room temperature in the furnace.

[0021] Preferably, in step S701, the heating rate V is 160-200°C / min, and the holding time t is 2h.

[0022] In addition, the present invention provides yttrium oxide-aluminum oxide composite ceramics prepared by the above-mentioned preparation method of yttrium oxide-aluminum oxide composite ceramics with high bonding strength.

[0023] The yttrium oxide-aluminum oxide composite ceramic in the present invention has high bonding strength, which meets the application requirements of alumina ceramic components, especially the use requirements of alumina ceramic components working in the inner cavity of an etching machine.

[0024] Furthermore, the present invention also provides the use of the aforementioned yttrium oxide-aluminum oxide composite ceramic in the inner cavity alumina ceramic components of an etcher.

[0025] The present invention has the following beneficial effects:

[0026] This technical solution provides an yttrium oxide-aluminum oxide composite ceramic with high bonding strength, as well as its preparation method and application. Alumina granulated powder and yttrium oxide granulated powder are sequentially added to a forming mold and compacted by vibration. Then, a cold isostatic pressing process is used to uniformly pressurize the powder raw materials in the forming mold, compress the volume of the powder raw materials, and expel pores to obtain a molded ceramic green body with uniform structure and high density. The molded ceramic green body is machined and sintered to further improve the strength, thereby obtaining an integrally sintered high-bonding-strength yttrium oxide-aluminum oxide composite ceramic. This solves the problems of poor bonding and easy peeling of the yttrium oxide etching-resistant protective coating in the prior art, while strengthening the protective function of the alumina substrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the specific embodiments of the present disclosure, the following briefly introduces the drawings required for use in the specific embodiments. In all the drawings, each element or part is not necessarily drawn according to the actual scale.

[0028] Figure 1 Schematic diagram of the structure of the forming die in the cold isostatic press of the present invention;

[0029] Figure 2 A diagram of a ceramic green body according to the present invention;

[0030] Figure 3 This is a diagram of the sintered yttrium oxide-aluminum oxide composite ceramic of the present invention;

[0031] Figure 4 This is the interface morphology of the yttrium oxide-aluminum oxide composite ceramic prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0032] The following embodiments of the technical solution of the present disclosure are described in detail with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present disclosure and are therefore only examples and are not intended to limit the scope of protection of the present disclosure.

[0033] It should be noted that, unless otherwise specified, the technical or scientific terms used in this application should have the common meanings understood by those skilled in the art to which the present invention belongs.

[0034] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0035] In addition, the terms "first," "second," etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the quantity of the technical features indicated. In the description of the present invention, "plurality" means two or more, unless otherwise specifically defined.

[0036] In this application, unless otherwise expressly specified or limited, terms such as "mounted," "connected," "connect," and "fixed" should be understood in a broad sense. For example, they may refer to fixed or detachable connections, or integration; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0037] In this application, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Furthermore, when a first feature is "above," "above," or "above" a second feature, it may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is "below," "below," or "below" a second feature, it may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0038] The preparation method of a yttrium oxide-aluminum oxide composite ceramic with high bonding strength provided in Examples 1-11 of the present invention, and the specific parameters of the preparation process of the yttrium oxide-aluminum oxide composite ceramic are shown in Table 1.

[0039] A method for preparing yttrium oxide-aluminum oxide composite ceramics with high bonding strength, comprising:

[0040] S1. Powder raw materials are yttrium oxide granulated powder and aluminum oxide granulated powder; the average particle size of the yttrium oxide granulated powder is 38 μm, and the average particle size of the aluminum oxide granulated powder is 57 μm;

[0041] S2, first adding a certain amount of alumina granulation powder into a forming mold of a cold isostatic press, and vibrating and compacting the alumina granulation powder in the forming mold;

[0042] S3, adding a fixed amount of yttrium oxide granulated powder into the forming mold of the cold isostatic press, and vibrating and compacting the yttrium oxide granulated powder in the forming mold; the forming mold is provided with positions A and B near the upper and lower ends thereof, respectively, and an interface is formed between the aluminum oxide granulated powder and the yttrium oxide granulated powder, and the interface is located between positions A and B of the forming mold; Figure 1 As shown;

[0043] S4, repeating steps S2 and S3 n times until the yttrium oxide granulated powder and the aluminum oxide granulated powder fill the entire forming mold; wherein n ≥ 0;

[0044] S5, placing the filled mold into a cold isostatic press for cold isostatic pressing; the cold isostatic pressing pressure P is 110-130 MPa, and the holding time m is 20-50 s to obtain a formed ceramic green body; Figure 2 As shown in the figure, the powder raw materials in the forming mold are uniformly pressurized by the cold isostatic pressing process, the powder raw materials are compressed in volume and the pores are discharged, so that a formed ceramic green body with uniform structure and high density can be obtained;

[0045] S6. Machining the formed ceramic green body to obtain at least one yttrium oxide-aluminum oxide composite ceramic green body, and processing the yttrium oxide-aluminum oxide composite ceramic green body into a designed shape, with the alumina portion serving as the alumina substrate and the yttrium oxide portion serving as the coating; when n=0, the number of yttrium oxide-aluminum oxide composite ceramic green bodies obtained is 1; when n=1, the number of yttrium oxide-aluminum oxide composite ceramic green bodies obtained is 2; when n=2, the number of yttrium oxide-aluminum oxide composite ceramic green bodies obtained is 3; and so on;

[0046] S7, transferring the yttrium oxide-aluminum oxide composite ceramic green body obtained in step S6 to a high-temperature sintering furnace for sintering, and naturally cooling to room temperature in the furnace to obtain a yttrium oxide-aluminum oxide composite ceramic; Figure 3 As shown in FIG. 1 , since yttrium oxide shrinks too much during the sintering process, it can be found that yttrium oxide is conical after sintering. The sintering process of the high-temperature sintering furnace includes the following steps:

[0047] S701: heating at a rate V of 160-240°C / min to 300°C, holding time th; then heating at a rate V to 400°C, holding time th; then heating at a rate V to 500°C, holding time th; then heating at a rate V to a sintering temperature T of 1650°C, holding time th; at a temperature between 300°C and 500°C, debinding the yttrium oxide-aluminum oxide composite ceramic green body in the furnace, i.e., decomposing and discharging the binder in the yttrium oxide granulation powder and the alumina granulation powder; wherein t is in the range of 1-4h;

[0048] S702: Cooling rate is 2℃ / min, from 1650℃ to 1000℃, and then naturally cooling to room temperature in the furnace.

[0049] Practice has shown that when the interface formed between the alumina granulated powder and the yttrium oxide granulated powder is located between position A and the upper end surface of the inner cavity of the forming mold or between position B and the lower end surface of the inner cavity of the forming mold, the bonding strength of the yttrium oxide-aluminum oxide composite ceramic obtained therein is poor, and a yttrium oxide-aluminum oxide composite ceramic green body cannot be machined alone; therefore, the interface is preferably located between position A and position B of the forming mold.

[0050] Wherein, in step S2 and step S3, alumina granulated powder and yttrium oxide granulated powder are added quantitatively, respectively. Here, "quantity" refers to the amount of raw material added designed by the technician according to the subsequent cold isostatic pressing, green body machining and sintering processes. Here, "quantity" can be adjusted by the technician according to different products. The ultimate guarantee is that after green body machining and sintering, the desired yttrium oxide-aluminum oxide composite ceramic can be obtained. For example, in one embodiment, a quantitative amount of alumina granulated powder is first added to the forming mold of the cold isostatic press, the ratio of the added volume of the alumina granulated powder to the volume of the inner cavity of the forming mold is 2:3, and the alumina granulated powder in the forming mold is vibrated and compacted; then, a quantitative amount of yttrium oxide granulated powder is added to the forming mold of the cold isostatic press, the ratio of the added volume of the yttrium oxide granulated powder to the volume of the inner cavity of the forming mold is 1:3, and the yttrium oxide granulated powder in the forming mold is vibrated and compacted; then, isostatic pressing is performed to obtain a formed ceramic green body. Of course, this embodiment is only an example of obtaining one yttrium oxide-alumina composite ceramic green body. Technicians can also reasonably adjust the amount of raw material added according to the actual shape and material ratio of the product to obtain one or more yttrium oxide-alumina composite ceramic green bodies after cold isostatic pressing.

[0051] Comparative Example 1

[0052] Comparative Example 1 was used as a blank control group. The coating was obtained by plasma spraying yttrium oxide granulated powder using the existing technology, and an aluminum oxide substrate was selected as the substrate.

[0053] Table 1

[0054]

[0055] Performance Testing

[0056] Test standard:

[0057] (1) The density of composite ceramics shall be in accordance with GB / T5593-1996.

[0058] (2) The bonding strength shall be in accordance with ASTMC1583 / D4541 / D7234 / D7522, ISO4624 / 16276-1, EN1542 / 12004-2, and AS / NZS1580.408.5.

[0059] Table 2

[0060]

[0061]

[0062] It is noteworthy that, as can be seen from the comparison between Examples 1-11 and Comparative Example 1, the bonding strength of the yttrium oxide-aluminum oxide composite ceramics prepared by this technical solution is significantly superior to the bonding strength of the yttrium oxide coating prepared by the conventional plasma spraying process. The bonding strength of the yttrium oxide-aluminum oxide composite ceramic prepared in Example 1 reached 27.55 MPa, far exceeding the bonding strength of the yttrium oxide coating prepared by the conventional method, laying the foundation for its application in related alumina ceramic components of etching machines.

[0063] Comparison of Examples 1-3 shows that as the cold isostatic pressing pressure increases from 110 MPa to 130 MPa, the density of the yttrium oxide coating gradually increases after sintering, as does the density of the alumina substrate. This indicates that increasing the isostatic pressing pressure gradually increases the density of the alumina substrate and the yttrium oxide coating, which contributes to improving the strength of the alumina substrate and the yttrium oxide coating. However, as the cold isostatic pressing pressure increases, the bond strength of the yttrium oxide-alumina composite ceramic increases and then stabilizes, reaching an optimal value of 27.55 MPa at a cold isostatic pressing pressure of 120 MPa. As the cold isostatic pressing pressure continues to increase, the density of the ceramic green body also continues to increase. When the pressure reaches 120 MPa, the density of the ceramic green body has reached its maximum value. At this time, the material strength is excellent and the bonding force is also the highest. When the pressure is less than 120 MPa, the density of the ceramic green body is not enough, the porosity inside the green body is high, and the strength of the material after sintering will also decrease accordingly. When the pressure is greater than 120 MPa, the density of the ceramic green body hardly changes (or the density increases very little). Greater pressure requires more energy and longer time, reducing production efficiency. Therefore, 120 MPa is the optimal applied pressure.

[0064] By comparing Example 1 with Examples 4-5, it can be seen that when the holding time of the cold isostatic press increases from 20s to 50s, the density of the yttrium oxide coating after sintering gradually increases as a whole, and the density of the alumina substrate also gradually increases as a whole; this indicates that with the gradual increase in the holding time, the density of the alumina substrate and the yttrium oxide coating gradually increases, which is beneficial to improving the strength of the alumina substrate and the yttrium oxide coating. However, it can be found that when the holding time exceeds 30s, the density of the yttrium oxide coating and the density of the alumina substrate do not substantially increase, indicating that setting the holding time to 30s is the most reasonable. At the same time, with the increase in the holding time, the bonding strength of the yttrium oxide-alumina composite ceramics tends to first increase and then decrease. As the holding time continues to increase, the density of the ceramic green body also continues to increase. When the holding time reaches 30s, the density of the ceramic green body has reached its maximum value. At this time, the material strength is excellent and the bonding force is also the highest. When the holding time is less than 30s, the density of the ceramic green body is not enough, the porosity inside the green body is high, and the strength of the material after sintering will also decrease accordingly. When the holding time is greater than 30s, the density of the ceramic green body hardly changes (or the density increases very little). Longer holding times require higher energy and more time, reducing production efficiency. Therefore, 30s is the optimal process parameter.

[0065] By comparing Example 1 with Examples 6-7, it can be seen that when the sintering heating rate increases from 160°C / min to 240°C / min, the density of the yttrium oxide coating after sintering first transitions smoothly and then gradually decreases, and the density of the alumina substrate also transitions smoothly and then gradually decreases. The bonding strength of the yttrium oxide-alumina composite ceramic first increases and then decreases. When the heating rate is greater than 200°C / min, due to the excessive heating rate, uneven heating and particle adhesion will occur; the rapid increase in temperature may not provide enough time for the particles to effectively rearrange, resulting in increased porosity and reduced structural density; rapid heating will also generate thermal stress, resulting in microcracks and other defects in the sintered alumina; on the contrary, when the heating rate is too low, the sintering time of the yttrium oxide-alumina composite ceramic green body is prolonged, and the particles thus have more sufficient energy to fully react. The prepared material is very dense and has low porosity, but the energy consumed by the slow heating rate is relatively high.

[0066] By comparing Example 1 with Examples 8-9, it can be seen that when the sintering temperature increases from 1580°C to 1700°C, the density of the yttrium oxide coating, the density of the alumina substrate, and the bonding strength of the yttrium oxide-alumina composite ceramic all show a trend of first increasing and then decreasing. When the sintering temperature is higher than 1650°C, the interior of the yttrium oxide-alumina composite ceramic green body continues to densify during the sintering process, and the porosity decreases, but at the same time, the grains inside it also grow synchronously. Therefore, the abnormal growth of the grains significantly reduces the strength of the ceramic; when the sintering temperature is lower than 1650°C, the yttrium oxide-alumina composite ceramic green body does not reach densification, has more pores, and the grain growth is incomplete, and the strength of the material is also significantly reduced.

[0067] By comparing Example 1 with Examples 10-11, it can be seen that when the sintering process holding time increases from 1h to 4h, the density of the yttrium oxide coating, the density of the alumina substrate, and the bonding strength of the yttrium oxide-alumina composite ceramic all show a trend of first increasing and then decreasing. When the holding time is less than 2h, the green body does not reach densification, has more pores, and the grain growth is incomplete, and the strength of the material is significantly reduced. When the holding time is higher than 2h, the inside of the green body is constantly densified, and the porosity decreases, but at the same time, the grains are also increasing synchronously, so the abnormal growth of the grains significantly reduces the strength of the material.

[0068] Figure 4 From the interface morphology diagram of the yttrium oxide-aluminum oxide composite ceramic prepared in Example 1, it is not difficult to find that yttrium oxide and alumina have undergone mutual interlocking at the interface, that is, part of the aluminum oxide of the alumina substrate is interlocked into the structure of the yttrium oxide, and part of the yttrium oxide of the yttrium oxide coating is interlocked into the structure of the alumina substrate. This mutual interlocking phenomenon effectively improves the bonding strength of the yttrium oxide-aluminum oxide composite ceramic.

[0069] The above embodiments are only used to illustrate the technical solutions of the present disclosure, rather than to limit them. Although the present disclosure has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present disclosure, and they should all be included in the scope of the claims and description of the present disclosure.

Claims

1. A method for preparing yttrium oxide-aluminum oxide composite ceramics with high bonding strength, characterized in that: The steps include: S1. Powder raw materials are yttrium oxide granulated powder and aluminum oxide granulated powder; S2, first adding a certain amount of alumina granulation powder into a forming mold of a cold isostatic press, and vibrating and compacting the alumina granulation powder in the forming mold; S3, adding a certain amount of yttrium oxide granulated powder into a forming mold of a cold isostatic press, and vibrating and compacting the yttrium oxide granulated powder in the forming mold; S4, repeating steps S2 and S3 n times until the yttrium oxide granulated powder and the aluminum oxide granulated powder fill the entire forming mold; wherein n ≥ 0; S5, placing the filled forming mold into a cold isostatic press for cold isostatic pressing; S6. Machining the formed ceramic green body in step S5 to obtain at least one yttrium oxide-aluminum oxide composite ceramic green body, and processing the yttrium oxide-aluminum oxide composite ceramic green body into a designed shape, with the alumina portion serving as the alumina substrate and the yttrium oxide portion serving as the coating; S7, transferring the yttrium oxide-aluminum oxide composite ceramic green body obtained in step S6 to a high-temperature sintering furnace for sintering, and naturally cooling to room temperature in the furnace to obtain the yttrium oxide-aluminum oxide composite ceramic; The sintering process of the high-temperature sintering furnace includes the following steps: S701: heating at a rate of V of 160-240°C / min to 300°C, holding time th; then heating at a rate of V to 400°C, holding time th; then heating at a rate of V to 500°C, holding time th; then heating at a rate of V to sintering temperature T of 1650°C, holding time th; where t is in the range of 1-4h; S702: Cooling rate is 2℃ / min, from 1650℃ to 1000℃, and then naturally cooling to room temperature in the furnace.

2. The method for preparing the yttrium oxide-aluminum oxide composite ceramic with high bonding strength according to claim 1, characterized in that: In step S1 , the average particle size of the yttrium oxide granulated powder was 38 μm, and the average particle size of the aluminum oxide granulated powder was 57 μm.

3. The method for preparing the yttrium oxide-aluminum oxide composite ceramic with high bonding strength according to claim 1, wherein: In step S3, positions A and B are respectively provided near the upper and lower ends of the forming mold, and an interface is formed between the alumina granulated powder and the yttrium oxide granulated powder. The interface is located between positions A and B of the forming mold.

4. The method for preparing the yttrium oxide-aluminum oxide composite ceramic with high bonding strength according to claim 1, wherein: In step S5, the cold isostatic pressing pressure P is 110-130 MPa.

5. The method for preparing the yttrium oxide-aluminum oxide composite ceramic with high bonding strength according to claim 1, wherein: In step S5, the holding time m is 20-50s.

6. The method for preparing the yttrium oxide-aluminum oxide composite ceramic with high bonding strength according to claim 5, characterized in that: In step S5, the holding time m is 20-30s.

7. The method for preparing the yttrium oxide-aluminum oxide composite ceramic with high bonding strength according to claim 1, characterized in that: In step S701, the heating rate V is 160-200°C / min, and the holding time t is 2h.

8. A yttrium oxide-aluminum oxide composite ceramic prepared by the method for preparing a yttrium oxide-aluminum oxide composite ceramic with high bonding strength according to any one of claims 1 to 7.

9. Use of the yttrium oxide-aluminum oxide composite ceramic according to claim 8 in alumina ceramic parts in the inner cavity of an etching machine.

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