Net size forming process of ceramic target material

Abstract

The application discloses a net size forming process of a ceramic target material, and has the technical scheme as follows: a vertical seat burning mode is adopted for loading and burning; during loading and burning, corundum sand is first placed around the table top of a kiln car to surround, high-temperature alumina hollow balls are placed in the middle, a level meter is used to adjust the horizontal state, and then a gasket which is homogenous with a blank body is placed; then, corundum sand is again placed on the periphery of the gasket to fix the hollow balls, the hollow balls are adjusted by the level meter to avoid blank body shrinkage obstruction, a green body base is then placed and the spacing is adjusted, the green body base is uniformly sprinkled with corundum sand to reduce shrinkage obstruction, a processed green body is carefully placed in the green body base and adjusted to be perpendicular to the green body base. The improved stacking process can change the phenomenon of uneven heating of the green body, reduce the machining amount, and improve the production efficiency.

Description

Technical Field

[0001] This invention relates to the field of target material production, and particularly to the net-size forming process of ceramic targets. Background Technology

[0002] Ceramic sputtering targets have wide applications in optics, large-area glass, solar photovoltaics, new panels, and semiconductors. Ceramic materials offer good stability and excellent coating performance, making them an irreplaceable type of sputtering target material. However, while ceramic materials are hard and wear-resistant, their manufacturing process also presents many challenges, such as difficult machining, long processing times, material brittleness, and high scrap rates. Therefore, achieving net-size molding for economically viable commercial products is essential.

[0003] Taking silicon nitride as an example, this material has the characteristics of high strength, high hardness, high temperature resistance, corrosion resistance, oxidation resistance, thermal shock resistance, creep resistance and good wear resistance. Moreover, it can still maintain its excellent performance at high temperatures and has been widely used in high-tech fields such as high-temperature gas turbines, aerospace, nuclear industry, high-efficiency engine components, and semiconductors.

[0004] For example, Chinese patent CN102432274B discloses a production process for alumina ceramic targets, including the following steps: 1) High-purity aluminum hydroxide is placed in a crucible and decomposed at high temperature to generate high-purity alumina particles, then alumina microparticles, and finally alumina particles of 35-50 micrometers; 2) Alumina spheres of 2-4 mm are formed; 3) The alumina spheres generated in step 2 are pressed into targets of various shapes at 25℃-100℃ and 100MPa; the temperature of the alumina spheres is maintained at 25℃-100℃ and the forming pressure is 100MPa during pressing; 4) The pressed targets are sintered three times at high temperature; 5) The products are packaged. The beneficial effects of this invention are: the alumina targets produced by this process have the characteristics of high purity, high density, good toughness, small shrinkage, and high product yield.

[0005] For example, Chinese patent CN115229947A discloses a CIP process mold and a production process for anodized ceramic targets. The mold body includes a mold body and ring assemblies. The mold body comprises a first mold frame, a second mold frame, and a shaft. The ring assemblies have a first through hole, and a first cavity is formed between the shaft and the second mold frame. Two ring assemblies are arranged opposite each other at opposite ends of the first mold frame. The two ring assemblies are respectively attached to the upper and lower surfaces of the material. During CIP processing, the gap between the first cavity and the material causes uneven stress on the surfaces of the mold frame, resulting in deformation of the upper and lower surfaces of the second mold frame. However, the ring assemblies, which are separately connected to the second mold frame, do not deform, thus ensuring the flatness of the upper and lower end faces of the produced anodized ceramic targets.

[0006] The aforementioned patents all possess some advantages, but also some disadvantages. Ceramic targets can operate at temperatures up to 800℃, exhibiting excellent self-lubricating properties, corrosion resistance, and wear resistance, and have high working strength. However, the production of large-size silicon nitride products mainly faces challenges such as large size, difficulty in sintering, uneven density gradient, low yield, and poor batch stability.

[0007] The main forming methods for ceramic substrates include tape casting, dry pressing, and roll forming. Among them, traditional dry pressing often presents challenges such as inaccurate thickness control and uneven thickness due to the non-uniformity of powder flow and the characteristics of mechanical pressurization, thus requiring subsequent machining.

[0008] Casting molding process has high production efficiency and low cost, and can achieve full automation, making it easy to produce in continuous batches. However, it also has the problems of the prepared cast film being prone to blistering, cracking, deformation, and uneven thickness, resulting in low yield, low flatness, uneven thickness, and the need for subsequent machining. Summary of the Invention

[0009] In view of the problems mentioned in the background art, the purpose of this invention is to provide a net-size forming process for ceramic targets to solve the problems mentioned in the background art.

[0010] The above-mentioned technical objective of the present invention is achieved through the following technical solution:

[0011] The net-size forming process for ceramic sputtering targets includes the following steps:

[0012] Step 1: First, make a metal master mold, and then use a process such as casting or hot pressing of elastic and plastic materials to make an elastic soft mold;

[0013] Step 2: Premix the ceramic powder and additives, and then ball mill the mixture thoroughly to reduce agglomeration;

[0014] Step 3: Granulate the mixture to form a particle size distribution that meets the requirements;

[0015] Step 4: Fill the CIP cold isostatic pressing sleeve with the powder prepared above;

[0016] Step 5: If the final product size is large, it can be pre-formed by molding first and then placed into a CIP cold isostatic pressing sleeve for further isostatic pressing.

[0017] Step 6: Seal the package using a vacuum-sealed plastic bag;

[0018] Step 7: Press the completed and sealed package into a green blank in a CIP cold isostatic pressing cylinder;

[0019] Step 8: When the density reaches more than 55% of the theoretical value and is found to be correct, it can proceed to the sintering process.

[0020] Preferably, in step 1, after the elastic soft mold is made, the burrs or corners of the elastic soft mold are repaired, and a layer of silicone oil is applied to the surface of the elastic soft mold.

[0021] Preferably, in step 2, the ceramic powder and additives are premixed and fully ball-milled to reduce agglomeration. The types of additives include calcium carbonate, zinc carbonate, calcium phosphate, and aluminum phosphate.

[0022] Preferably, the mass ratio of the ceramic powder to the additive is 97:3, and the mass ratio of calcium carbonate, zinc carbonate, calcium phosphate, and aluminum phosphate is 1:1:1:1.

[0023] Preferably, in step 4, when filling the prepared powder into the CIP cold isostatic pressing sleeve, a negative pressure pump is used for injection, the molding pressure in the CIP cold isostatic pressing sleeve is controlled to be 100-200 MPa, and the pressure holding time is 20-300 seconds.

[0024] Preferably, in step 6, when sealing the package, a vacuum plastic bag is used for sealing, and a vacuum pump is used to evacuate the vacuum. When the vacuum level P of the evacuation pipeline is measured to be less than 0.1 Pa, the diffusion pump is turned on to continuously evacuate the vacuum.

[0025] Preferably, in step 8, when the density reaches more than 55% of the theoretical value and is found to be correct, the sintering process can be started. The sintering process includes pre-firing and sintering heat preservation. During pre-firing, the temperature is pre-fired to 200℃-230℃ under nitrogen protection for 10-20 minutes.

[0026] Preferably, during the sintering and heat preservation step of the sintering process, sintering is carried out at 1200-1300℃ for 8-10 hours, and after sintering, the temperature is maintained and cooled in a 50℃ oven.

[0027] In summary, the present invention has the following main beneficial effects:

[0028] The ceramic target material prepared by the method of this invention meets the mechanical performance requirements while reducing the shrinkage rate of the green body during subsequent sintering. Data shows that the shrinkage rate can be reduced by 80%. During the sintering process, as the green body shrinks, defects such as pores and microcracks are usually left in the final product, affecting the quality of the target material. Furthermore, temperature and other factors during sintering can introduce internal stress into the final product, which also affects the quality of the target material. Minimizing the shrinkage during sintering effectively reduces the impact of these factors on the performance of the final product. The method of this invention is simple, requires minimal machining allowance, and is economical. Detailed Implementation

[0029] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] Example 1

[0031] The net-size forming process for ceramic sputtering targets includes the following steps:

[0032] Step 1: First, make a metal master mold, and then use a process such as casting or hot pressing of elastic and plastic materials to make an elastic soft mold;

[0033] Step 2: Premix the ceramic powder and additives, and then ball mill the mixture thoroughly to reduce agglomeration;

[0034] Step 3: Granulate the mixture to form a particle size distribution that meets the requirements;

[0035] Step 4: Fill the CIP cold isostatic pressing sleeve with the powder prepared above;

[0036] Step 5: If the final product size is large, it can be pre-formed by molding first and then placed into a CIP cold isostatic pressing sleeve for further isostatic pressing.

[0037] Step 6: Seal the package using a vacuum-sealed plastic bag;

[0038] Step 7: Press the completed and sealed package into a green blank in a CIP cold isostatic pressing cylinder;

[0039] Step 8: When the density reaches more than 55% of the theoretical value and is found to be correct, it can proceed to the sintering process.

[0040] In step 1, after the elastic soft mold is formed, the burrs or edges of the elastic soft mold are repaired, and a layer of silicone oil is applied to the surface of the elastic soft mold. In step 2, the ceramic powder and additives are premixed and fully ball-milled to reduce agglomeration. The types of additives include calcium carbonate, zinc carbonate, calcium phosphate, and aluminum phosphate. The mass ratio of ceramic powder to additives is 97:3, and the mass ratio of calcium carbonate, zinc carbonate, calcium phosphate, and aluminum phosphate is 1:1:1:1.

[0041] In step 4, when filling the prepared powder into the CIP cold isostatic pressing sleeve, a negative pressure pump is used for injection, controlling the molding pressure in the CIP cold isostatic pressing sleeve to be 100-200 MPa, and the pressure holding time is 20-300 seconds. In step 6, when sealing the sleeve, a vacuum plastic bag is used for sealing, and a vacuum pump is used for evacuation. When the vacuum degree P of the evacuation pipe is measured to be less than 0.1 Pa, the diffusion pump is turned on for continuous evacuation. In step 8, when the density reaches more than 55% of the theoretical value and is found to be correct, the sintering process can begin. The sintering process includes pre-firing and sintering heat preservation. During pre-firing, the temperature is pre-fired to 200℃-230℃ under nitrogen protection for 10-20 minutes. During the sintering heat preservation step of the sintering process, sintering is carried out at 1200-1300℃ for 8-10 hours. After sintering, the temperature is kept cool in a 50℃ oven.

[0042] The ceramic target material prepared by the method of this invention not only meets the mechanical performance requirements but also reduces the shrinkage rate of the green body during subsequent sintering. Data shows that the shrinkage rate can be reduced by 80%. During the sintering process, as the green body shrinks, defects such as pores and microcracks are usually left in the final product, affecting the quality of the target material. Furthermore, temperature and other factors during sintering can introduce internal stress into the final product, which also affects the quality of the target material. Minimizing the shrinkage during sintering effectively reduces the impact of these factors on the performance of the final product. The method of this invention is simple, requires minimal machining allowance, and is economical.

[0043] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A process for forming the net dimensions of ceramic targets, characterized in that: Includes the following steps: Step 1: First, make a metal master mold, then cast or hot-press elastomeric material to make an elastic soft mold; Step 2: Premix the ceramic powder and additives, and then ball mill the mixture thoroughly to reduce agglomeration; Step 3: Granulate the mixture to form a particle size distribution that meets the requirements; Step 4: Fill the CIP cold isostatic pressing sleeve with the powder prepared above, and use a negative pressure pump to pump it in. Control the molding pressure in the CIP cold isostatic pressing sleeve to be 100-200 MPa, and the holding time to be 20-300 seconds. Step 5: Seal the package by using a vacuum plastic bag and a vacuum pump to evacuate the vacuum. When the vacuum level P of the evacuation pipeline is less than 0.1 Pa, start the diffusion pump to continuously evacuate the vacuum. Step 6: Press the completed and sealed package into a green blank in a CIP cold isostatic pressing cylinder; Step 7: When the density reaches more than 55% of the theoretical value, and is found to be correct after testing, proceed to the sintering process.

2. The net-size forming process for the ceramic target material according to claim 1, characterized in that: In step 1, after the elastic soft mold is made, the burrs or corners of the elastic soft film are repaired, and a layer of silicone oil is applied to the surface of the elastic soft film.

3. The net-size forming process for the ceramic target material according to claim 1, characterized in that: In step 2, the ceramic powder and additives are premixed and fully ball-milled to reduce agglomeration. The types of additives include calcium carbonate, zinc carbonate, calcium phosphate, and aluminum phosphate.

4. The net-size forming process for the ceramic target material according to claim 3, characterized in that: The mass ratio of ceramic powder to additives is 97:3, and the mass ratio of calcium carbonate, zinc carbonate, calcium phosphate, and aluminum phosphate is 1:1:1:

1.

5. The net-size forming process for the ceramic target material according to claim 1, characterized in that: In step 7, when the density reaches more than 55% of the theoretical value, and is found to be correct, it enters the sintering process. The sintering process includes pre-firing and sintering heat preservation. During pre-firing, it is pre-firing at 200℃-230℃ under nitrogen protection for 10-20 minutes.

6. The net-size forming process for the ceramic target material according to claim 5, characterized in that: During the sintering and heat preservation step of the sintering process, sintering is carried out at 1200-1300℃ for 8-10 hours, and after sintering, the temperature is maintained and cooled in a 50℃ oven.