Cerium oxide / yttrium oxide composite stabilized zirconia grinding media and method of manufacture

Abstract

The application provides a ceria / yttria composite stabilized zirconia grinding medium and a preparation method. The method comprises the following steps: step one, mixing zirconia, ceria, yttria and kaolin, and then adding an appropriate amount of dispersant and water to obtain a slurry; step two, performing centrifugal spray drying on the slurry to obtain ceria / yttria composite stabilized zirconia powder; step three, adding the ceria / yttria composite stabilized zirconia powder into a binder, and then rolling to form a green body of spherical grinding medium; and step four, sintering and polishing the green body of spherical grinding medium to obtain the ceria / yttria composite stabilized zirconia grinding medium. The method can obtain low particle size and high specific surface area through high-temperature ball milling, and can also promote the solid solution of the stabilizer into the zirconia crystal lattice through heat treatment, so as to improve sintering activity, reduce sintering temperature and reduce production cost.

Description

Technical Field

[0001] This invention relates to the field of zirconia ceramics technology, and in particular to a cerium oxide / yttrium oxide composite stabilized zirconia grinding media and its preparation method. Background Technology

[0002] Tetragonal zirconia (TZP) ceramics are among the most representative ceramics, widely used in various fields due to their high strength, high hardness, high fracture toughness, and good biocompatibility. Tetragonal zirconia, in particular, exhibits excellent wear resistance as an abrasive media and is widely used in coatings, inks, and cathode material grinding.

[0003] Yttrium oxide-stabilized tetragonal zirconia ceramics (Y-TZP) are the most studied TZP materials. The yttrium oxide content is crucial to the performance of zirconia ceramics. For example, when the yttrium oxide content is below 2 mol%, it is difficult to obtain a high content of tetragonal zirconia. The material exhibits the best toughness at a yttrium oxide content of 2 mol%, while the material has the highest strength when the content is between 2 and 3 mol%. However, Y-TZP is prone to low-temperature aging when used in low-temperature and humid environments, especially in the temperature range of 65-400℃. This is mainly manifested as the formation of micro or macro microcracks on the surface, which affects the mechanical properties of the material and limits its application in special environments. Therefore, preventing low-temperature aging of Y-TZP is essential. TZP ceramics with CeO2 as a stabilizer have excellent fracture toughness and anti-aging properties, but compared with Y-TZP, Ce-TZP requires higher sintering temperatures and longer holding times for densification. Ce-TZP grains are coarser, resulting in lower strength and hardness.

[0004] ZrO2 ceramics stabilized with a single stabilizer have certain limitations in practical applications. By adding two or more stabilizers to the ZrO2 matrix, ZrO2 composite ceramics with better overall performance can be obtained. Many scholars have also conducted a series of studies on co-stabilized zirconia ceramics with multiple stabilizers. In their paper "Low-Temperature Aging of YCe-TZP Ceramics," Yin Bangyue et al. prepared YCe-TZP ceramics with different ratios using a co-precipitation process. After sintering at 1450℃, they conducted low-temperature aging tests. 3Y4Ce-TZP showed almost no aging; during the aging process, a CeO2 protective layer formed on the surface of 3Y4Ce-TZP, preventing the formation of Y-OH bonds, thus effectively suppressing the t (tetragonal phase) → m (monoclinic phase) aging phase transformation. However, the introduction of cerium oxide as a stabilizer led to a higher sintering temperature for zirconia, resulting in a reduction in some mechanical properties, thus affecting its wear resistance as a grinding media. Currently, there are few reports on the application of cerium oxide and yttrium oxide composite stabilized zirconia materials in grinding media. Ensuring both excellent low-temperature aging resistance and wear resistance is crucial for promoting their application in the grinding media field. Sintering of grinding media is also the most energy-intensive step; therefore, reducing the sintering temperature is a key research focus for zirconia grinding media. Summary of the Invention

[0005] To overcome the shortcomings of existing technologies, this invention provides a cerium oxide / yttrium oxide composite stabilized zirconia grinding media and its preparation method. This method enables low-temperature sintering to achieve density, and simultaneously produces a cerium oxide / yttrium oxide composite stabilized zirconia grinding media and its preparation method that possess excellent anti-aging and wear-resistant properties, thereby extending its service life and reducing production costs.

[0006] To achieve the above objectives, the present invention provides a cerium oxide / yttrium oxide composite stabilized zirconium oxide grinding media and a preparation method thereof, wherein the preparation method is as follows:

[0007] Step 1: Zirconia, cerium oxide, yttrium oxide and kaolin are mixed in a certain proportion, and then an appropriate amount of dispersant and deionized water are added and ground to obtain a uniformly mixed slurry.

[0008] Step 2: The uniformly mixed slurry is centrifugally spray-dried to obtain cerium oxide and yttrium oxide composite stabilized zirconia powder; the spray drying atomizing disc speed is 9000-11000 r / min, the inlet temperature is 240-260℃, and the outlet temperature is 95-110℃ to ensure that the granulated powder has good sphericity and flowability.

[0009] Step 3: Add cerium oxide and yttrium oxide composite stabilized zirconium oxide powder to the binder and roll it to obtain a spherical grinding media green blank;

[0010] Step 4: Polishing after sintering the green grinding media to obtain cerium oxide and yttrium oxide composite stabilized zirconium oxide grinding media.

[0011] Preferably, in step one, the amounts of zirconium oxide, cerium oxide, yttrium oxide, and kaolin added are 85-90 wt%, 10-15 wt%, 1-2 wt%, and 0.1-0.5 wt%, respectively.

[0012] Preferably, in step one, the dispersant added is Dolapix ce64, and the amount added is 0.5wt%.

[0013] Preferably, in step one, the amount of deionized water added is 50 wt%, and the solid content of the slurry is 50 wt%.

[0014] Preferably, in step one, the slurry temperature is maintained at 70-90℃ during the grinding process.

[0015] Preferably, in step one, the particle size D50 of the mixed slurry is controlled within the range of 0.15-0.2 μm.

[0016] Preferably, in step three, the binder used in the molding process is a composition of PVA, glycerin, and water.

[0017] Preferably, in step four, the grinding media green blank sintering process is carried out by heating to 1300-1350℃ at a heating rate of 2℃ / min, holding at the temperature for 2 hours under pressureless conditions in an air atmosphere, and then naturally cooling to room temperature.

[0018] Preferably, in step four, the sintered grinding media is polished using a sand mill with a linear speed of 8 m / s, and the polishing material is white corundum with an addition amount of 2 wt%.

[0019] The beneficial effects of this invention are as follows:

[0020] This invention achieves low particle size and high specific surface area through high-temperature ball milling, while simultaneously promoting the solidification of stabilizers into the zirconia lattice through heat treatment, thereby improving sintering activity. Stable tetragonal zirconia with a density as high as 6.13-6.14 g / m³ can be obtained by low-temperature sintering (1300-1350℃). 3 The surface roughness is reduced through subsequent polishing. Considering the above properties, it exhibits excellent wear resistance during the grinding process, with self-wearing consumption of less than 10ppm / h, thus extending its service life.

[0021] This invention employs a solid-state synthesis process, adding a small amount of yttrium oxide to cerium oxide-stabilized zirconia ceramics to improve mechanical properties, and adding kaolin as a sintering aid. Kaolin is mainly composed of alumina and silicon dioxide, and its addition is used to improve sintering activity, reduce sintering temperature, obtain excellent resistance to low-temperature aging, and reduce production costs. Attached Figure Description

[0022] Figure 1 The X-ray diffraction pattern of Example 1 before aging;

[0023] Figure 2 The X-ray diffraction pattern after aging in Example 1;

[0024] Figure 3 The X-ray diffraction pattern before aging in Example 2;

[0025] Figure 4 The X-ray diffraction pattern after aging in Example 2;

[0026] Figure 5 The X-ray diffraction pattern of Comparative Example 1 before aging;

[0027] Figure 6 The X-ray diffraction pattern of Comparative Example 1 after aging;

[0028] Figure 7 The X-ray diffraction pattern of Comparative Example 2 before aging;

[0029] Figure 8 The X-ray diffraction pattern of Comparative Example 2 after aging;

[0030] Figure 9 The X-ray diffraction pattern of Comparative Example 3 before aging;

[0031] Figure 10 The X-ray diffraction pattern of Comparative Example 3 after aging;

[0032] Figure 11 The X-ray diffraction pattern of Comparative Example 4 before aging;

[0033] Figure 12 The X-ray diffraction pattern of Comparative Example 4 after aging;

[0034] Figure 13 The X-ray diffraction pattern of Comparative Example 5 before aging;

[0035] Figure 14 The X-ray diffraction pattern of Comparative Example 5 after aging is shown. Detailed Implementation

[0036] To better illustrate the purpose, technical solution, and advantages of this invention, the following will provide further explanation of this application in conjunction with specific embodiments.

[0037] The testing method in this invention:

[0038] 1. Grinding media density: Archimedes' water displacement method,

[0039] 2. Grinding media wear: For a 1L sand mill, with 2.6kg of grinding media added (denoted as m0), the wear is measured in clean water at a linear velocity of 12m / s for 20 hours (t). The weight loss is calculated by weighing; the weight before the test is recorded as m1, and the weight after the test is recorded as m. 2，

[0040] ;

[0041] 3. Phase content: X-ray diffractometer (XRD);

[0042] 4. Low-temperature anti-aging performance test: The sample was placed in a hydrothermal reactor, water was added to a filling rate of 80%, and hydrothermal treatment was carried out at 200℃ for 48 hours.

[0043] Example 1:

[0044] Zirconia, cerium oxide, yttrium oxide, and kaolin were mixed in proportions of 86.2 wt%, 12 wt%, 1.5 wt%, and 0.3 wt%, respectively. Pure water was then added to bring the solid content to 50%. The mixture was ground using a drum ball mill, with 0.5 wt% Dolapix CE64 added as a dispersant. The grinding process was controlled at approximately 80°C until a particle size D was reached. 50 When the atomizing disc reaches 0.15 μm, the slurry is transferred to a granulation tower for spray granulation. The atomizing disc rotates at 10,000 r / min, the inlet temperature is 250℃, and the outlet temperature is 105℃, thus obtaining cerium oxide and yttrium oxide composite stabilized zirconium oxide powder.

[0045] The powder was mixed with a binder (PVA, glycerol, and deionized water in a ratio of 1:0.5:90) and rolled to prepare green grinding media balls. The binder dosage was 8-10 wt%. The green balls were heated from room temperature to 1330℃ in air at a rate of 2℃ / min, held at that temperature for 2.5 h, and then allowed to cool naturally to room temperature. 2 wt% white fused alumina was then added, and the mixture was polished in a sand mill at a linear velocity of 8 m / s until the surface was smooth, yielding cerium oxide / yttrium oxide composite stabilized zirconia grinding media balls. The density of this grinding media was 6.138 g / m³. 3 The wear test result was 8.0 ppm / h. After aging at 200℃ for 48 hours, the tetragonal phase content was 100%. Figure 1 , Figure 2 The figures show the X-ray diffraction patterns of the grinding media before and after aging. The vertical axis represents the relative intensity, and the horizontal axis represents the diffraction angle 2θ.

[0046] Example 2:

[0047] Zirconia, cerium oxide, yttrium oxide, and kaolin were mixed in proportions of 85wt%, 13.2wt%, 1.5wt%, and 0.3wt%, respectively. Pure water was then added to bring the solid content to 50%. The mixture was ground using a roller ball mill with 0.5wt% Dolapix CE64 (Sima Chemical CE64) added as a dispersant. The grinding process was carried out at a temperature of approximately 80℃. When the particle size D50 reached 0.15µm, the slurry was transferred to a granulation tower for spray granulation. The atomizing disc rotated at 10,000 r / min, with an inlet temperature of 250℃ and an outlet temperature of 105℃, thus obtaining cerium oxide and yttrium oxide composite stabilized zirconia powder.

[0048] The powder was mixed with a binder (PVA, glycerol, and deionized water in a ratio of 1:0.5:90) and rolled to prepare green grinding media balls. The green balls were heated from room temperature to 1330℃ in air at a rate of 2℃ / min, held at that temperature for 2.5h, and then allowed to cool naturally to room temperature. 2wt% white corundum was added, and the balls were polished in a sand mill at a linear velocity of 8m / s until the surface was smooth, yielding cerium oxide / yttrium oxide composite stabilized zirconia grinding media balls. The grinding media had a density of 6.140 g / m³, a wear test result of 8.2 ppm / h, and after aging at 200℃ for 48h under hydrothermal conditions, the tetragonal phase content was 100%. Figure 3 , Figure 4 The figures show the X-ray diffraction patterns of the grinding media before and after aging. The vertical axis represents the relative intensity, and the horizontal axis represents the diffraction angle 2θ.

[0049] Comparative Example 1:

[0050] Compared to Example 1, zirconium oxide, cerium oxide, yttrium oxide, and kaolin were mixed in proportions of 86.2 wt%, 13.5 wt%, 0 wt%, and 0.3 wt%, respectively, with all other conditions remaining the same. The resulting grinding media balls had a density of 5.967 g / m³, an abrasion test result of 3961.4 ppm / h, and after aging at 200°C for 48 h under hydrothermal conditions, the tetragonal phase content was 12%. Figure 5 , Figure 6 The figures show the X-ray diffraction patterns of the grinding media before and after aging. The vertical axis represents the relative intensity, and the horizontal axis represents the diffraction angle 2θ.

[0051] Comparative Example 2:

[0052] Compared to Example 1, zirconium oxide, cerium oxide, yttrium oxide, and kaolin were mixed in proportions of 86.5 wt%, 12 wt%, 1.5 wt%, and 0 wt%, respectively, with all other conditions remaining the same. The resulting grinding media balls had a density of 6.055 g / m³, an abrasion test result of 1807.0 ppm / h, and after aging at 200°C for 48 h under hydrothermal conditions, the tetragonal phase content was 95%. Figure 7 , Figure 8The figures show the X-ray diffraction patterns of the grinding media before and after aging. The vertical axis represents the relative intensity, and the horizontal axis represents the diffraction angle 2θ.

[0053] Comparative Example 3:

[0054] Compared to Example 1, 0.13 wt% alumina and 0.17 wt% silica were used to replace kaolin, with other conditions remaining the same. The resulting grinding media was sintered at 1330°C and had a density of 6.101 g / m³. 3 The wear test result was 55.6 ppm / h. After aging at 200℃ for 48 hours, the tetragonal phase content was 100%. Figure 9 , Figure 10 The figures show the X-ray diffraction patterns of the grinding media before and after aging. The vertical axis represents the relative intensity, and the horizontal axis represents the diffraction angle 2θ.

[0055] Comparative Example 4:

[0056] Compared to Example 1, the powder grinding process was controlled at around 30°C, with all other conditions remaining the same. The resulting grinding media balls had a density of 6.109 g / m³, an abrasion test result of 298.2 ppm / h, and after aging at 200°C for 48 hours under hydrothermal conditions, the tetragonal phase content was 92%. Figure 11 , Figure 12 The figures show the X-ray diffraction patterns of the grinding media before and after aging. The vertical axis represents the relative intensity, and the horizontal axis represents the diffraction angle 2θ.

[0057] Comparative Example 5:

[0058] Compared to Example 1, the powder grinding process was controlled at a temperature of around 50°C, with all other conditions remaining the same, resulting in a grinding media ball density of 6.120 g / m³. 3 The wear test result was 205.0 ppm / h. After aging at 200℃ for 48 hours under hydrothermal conditions, the tetragonal phase content was 94%. Figure 13 , Figure 14 The figures show the X-ray diffraction patterns of the grinding media before and after aging. The vertical axis represents the relative intensity, and the horizontal axis represents the diffraction angle 2θ.

[0059] Table 1 Experimental parameters for each embodiment and comparative example

[0060] ,

[0061] Table 2 Performance test parameters for each embodiment and comparative example

[0062] .

[0063] As seen in Example 1 and Comparative Example 1, the addition of yttrium oxide, combined with cerium oxide to stabilize zirconia, helps improve its wear resistance. This is because in the cerium oxide and yttrium oxide composite stabilized zirconia, the Y... 3+ Grain boundary segregation inhibits grain growth, improves the strength, hardness, and density of Ce-TZP, thereby achieving excellent wear resistance.

[0064] As seen in Examples 1, 2, and 3, the addition of kaolin can act as a sintering aid to accelerate the densification of zirconium oxide and achieve high density. The main components of kaolin are alumina and silicon dioxide, along with a small amount of alkali metal oxides. These components work together as sintering aids during the sintering process. Alumina inhibits grain growth, while silicon dioxide readily forms a eutectic liquid phase with the stabilizers in ZrO2 ceramics, thereby improving sintering mass transfer efficiency, promoting ceramic densification, and consequently affecting the mechanical properties of the ceramic.

[0065] Based on Examples 1, 4, and 5, heat treatment at 70-90°C during the grinding process significantly improves its density, wear resistance, and aging resistance. It is speculated that high temperature can promote the growth of Y... 3+ and Ce 4+ The solid solution is incorporated into the zirconia lattice, reducing the amount of stabilizer at grain boundaries. The increased chemical free enthalpy of the solid solution and the increased intergranular confinement energy maintain the tetragonal phase, reducing the volume expansion and microcracks caused by the t-ZrO2→m-ZrO2 transformation, thus improving wear resistance. In composite stabilized zirconia prepared under low-temperature conditions, most of the stabilizer is located at grain boundaries. Under low-temperature aging conditions, it easily precipitates into the aqueous solution, leading to phase transformation and thus reducing wear resistance and exhibiting lower anti-aging properties.

[0066] The wear resistance of zirconia grinding media is mainly determined by external and internal factors. When external factors, i.e., usage conditions and environment, are fixed, we can only improve wear resistance by addressing internal factors. Internal factors mainly include phase composition, grain size, toughness, elastic modulus, strength, hardness, and porosity (density). 3+ The presence of Ce gives it high strength and hardness. 4+ The presence of cerium oxide and yttrium oxide enhances its toughness and anti-aging properties, making it less prone to cracking caused by phase transformation under prolonged external forces. The addition of kaolin, a sintering aid, significantly lowers the sintering temperature, thereby reducing the grain size of the sintered body. Smaller grain sizes help maintain a stable tetragonal phase. High sintering activity promotes densification, accelerates the removal of pores, and reduces the presence of pores, resulting in ultra-high density. Therefore, cerium oxide and yttrium oxide composite stabilized zirconia grinding media exhibit excellent comprehensive mechanical properties when sintered at low temperatures, thus improving its wear resistance.

[0067] In summary, the preparation method of the cerium oxide and yttrium oxide composite stabilized zirconia grinding media of the present invention achieves an ultra-low sintering temperature of 1300-1350℃ through the adjustment of raw material ratio, sintering aids and control of ball milling process. The resulting zirconia grinding media has excellent low-temperature anti-aging properties and wear resistance, and its ultra-high density also helps it to be used in high-viscosity grinding environments.

[0068] This invention provides a cerium oxide / yttrium oxide composite stabilized zirconia grinding media and its preparation method. The preparation process is as follows: Step 1: Zirconia, cerium oxide, yttrium oxide, and kaolin are mixed, and then a dispersant and deionized water are added and ground to obtain a uniformly mixed slurry; Step 2: The uniformly mixed slurry is centrifugally spray-dried to obtain cerium oxide / yttrium oxide composite stabilized zirconia powder; Step 3: The cerium oxide / yttrium oxide composite stabilized zirconia powder is added to a binder and rolled to form a spherical grinding media green; Step 4: The grinding media green is sintered and then polished to obtain the cerium oxide / yttrium oxide composite stabilized zirconia grinding media. The yttrium oxide and cerium oxide composite stabilized zirconia, combined with heat treatment during ball milling, enables tetragonal zirconia to remain stable for a long time in a low-temperature and humid environment, inhibiting phase transformation and exhibiting superior anti-aging properties, thus extending its service life. High density and reduced cost can be achieved by controlling the particle size, adding kaolin as a sintering aid, lowering the sintering temperature, using pressureless sintering, and sintering in an air atmosphere. The resulting grinding media exhibits excellent comprehensive mechanical properties, good wear resistance, low wear, and reduced usage costs.

[0069] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for preparing a cerium oxide / yttrium oxide composite stabilized zirconium oxide grinding media, characterized in that: Includes the following steps, Step 1: Mix zirconium oxide, cerium oxide, yttrium oxide and kaolin, then add an appropriate amount of dispersant and water and grind to obtain a slurry. During the grinding process, the slurry temperature is maintained at 70-90℃, and the particle size D50 of the mixed slurry is controlled within the range of 0.15-0.2μm. Step 2: The slurry is centrifuged and spray-dried to obtain cerium oxide / yttrium oxide composite stabilized zirconia powder; the spray drying atomizing disc speed is 9000-11000 r / min, the inlet temperature is 240-260℃, and the outlet temperature is 95-110℃ to ensure that the granulated powder has good sphericity and flowability. Step 3: Add cerium oxide / yttrium oxide composite stabilized zirconium oxide powder to the binder and roll it to form a spherical grinding media green blank; Step 4: After sintering and polishing the spherical grinding media green blank, cerium oxide / yttrium oxide composite stabilized zirconia grinding media is obtained. During the sintering process of the spherical grinding media green blank, the temperature is raised to 1300-1350℃ at a heating rate of 2℃ / min, and held at that temperature for 2-2.5h under pressureless conditions in an air atmosphere, and then naturally cooled to room temperature. In step one, the amounts of zirconium oxide, cerium oxide, yttrium oxide, and kaolin added are 85-90 wt%, 10-15 wt%, 1-2 wt%, and 0.1-0.5 wt%, respectively.

2. The method for preparing the cerium oxide / yttrium oxide composite stabilized zirconium oxide grinding media according to claim 1, characterized in that: In step one, the dispersant added is Dolapix ce64, and the amount added is 0.5wt%.

3. The method for preparing the cerium oxide / yttrium oxide composite stabilized zirconium oxide grinding media according to claim 1, characterized in that: In step one, the water content is 50%, and the slurry solid content is 50%.

4. The method for preparing the cerium oxide / yttrium oxide composite stabilized zirconium oxide grinding media according to claim 1, characterized in that: In step three, the binder used in the molding process is a mixture of PVA, glycerin, and water.

5. The method for preparing the cerium oxide / yttrium oxide composite stabilized zirconium oxide grinding media according to claim 1, characterized in that: In step four, the sintered grinding media is polished using a sand mill at a linear speed of 8 m / s, and the polishing material is white corundum with an addition amount of 2 wt%.

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