Zirconia composite ceramic microbeads

Abstract

The present application provides a zirconia composite ceramic microbead, raw materials containing, by weight percentage: 60%≤ZrO2+HfO2≤65%; 15%≤SiO2≤19%; 9≤Al2O3≤12%; 2%≤CeO2+Y2O3≤4%; 3%≤NaOH or Na2O≤3.5%, 3%≤Sc2O3≤5%, when 3%≤Sc2O3≤5% is added to the raw materials, the surface precipitation spot disappears, and the wear ratio of the zirconia composite ceramic microbead is <0.72.

Description

Technical Field

[0001] This invention relates to a zirconia composite ceramic microsphere, particularly to beads formed from molten ceramic, to a corresponding preparation method, and to the use of the microsphere as a grinding or surface treatment material. Background Technology

[0002] Grinding media are fundamental materials in powder production, and they are also a crucial component. Grinding media are one of the key factors determining grinding efficiency. The performance requirements for grinding media mainly include the following:

[0003] (1) Abrasion resistance

[0004] The wear resistance of grinding media directly affects its performance during use. Grinding media should not experience significant wear during use. If the wear of grinding media is high, it will not only affect the lifespan of the grinding media itself, but also contaminate the material being ground. Therefore, the wear of grinding media should be as low as possible.

[0005] (2) Density

[0006] The higher the density of the grinding media, the higher its specific gravity. Under the same conditions, grinding media with a higher specific gravity generate more kinetic energy, thus requiring less time for the grinding process and resulting in higher grinding efficiency.

[0007] (3) Strength and hardness

[0008] Crushing strength characterizes the maximum impact force that grinding media can withstand. Because grinding media undergo numerous interactions during use, higher crushing strength means a lower chance of damage. The hardness of the material being ground determines the application of the grinding media. The hardness of the grinding media is typically greater than the hardness of the material being ground; otherwise, significant losses will occur.

[0009] (4) Roundness and dimensions

[0010] For spherical grinding media, the better the sphericity and the smaller the roundness deviation, the better. Better roundness results in a more uniform diameter distribution of the product obtained from grinding. The smaller the size of the grinding balls, the more contact points there are between the balls during the grinding process, and the more opportunities the material is to be ground. Generally speaking, the smaller the particle size of the material being ground, the smaller the diameter of the grinding media should also be.

[0011] (5) Smoothness

[0012] Grinding balls need to have a smooth, glossy surface; the smoother the surface, the less wear. The factor determining whether a grinding ball surface has a glossy finish is the smoothness of the spherical surface; a smooth spherical surface has a good mirror effect, while a rough spherical surface has a poor mirror effect. Factors affecting the flatness of the spherical surface mainly include the internal structure of the material and the degree of external processing of the spherical surface. Among these aspects, wear resistance is the most important and core indicator for selecting grinding balls. The quality of wear resistance directly affects the purity and fineness of the material being ground. The size and specific gravity of the spherical grinding media affect the grinding efficiency, and in some special cases, there are also requirements for the whiteness of the spherical grinding media. In short, good grinding media should have low wear, high density and hardness, high impact resistance, and no harmful side effects on the material being ground.

[0013] In the prior art, CN110642619A discloses ceramic blasting microspheres containing molten zirconium oxide, relating to a mixture of particles containing molten alumina-zirconia, having the following chemical composition based on the weight percentage of oxides, totaling 100%: 55% < ZrO2 + HfO2 < 65%; 22% < SiO2 < 30%; 9% < Al2O3 < 12%; 1.5% < Y2O3 < 5%; 2% < co-solvent < 5%, and the silica / alumina content ratio is greater than 2:1 and less than 3:1, with sodium oxide as the co-solvent. In addition to optimized grinding characteristics, the molten ceramic particles also exhibit excellent fracture strength or a good balance between wear resistance and fracture strength.

[0014] The French company Saint-Gauby's European Experimental and Research Centre (CN101998940A) relates to a molten ceramic particle characterized by having the following chemical composition, based on oxide weight percentages totaling 100%: 50% < ZrO2 + HfO2 < 70%; 10% < SiO2 < 30%; 6.5% < MgO < 9.5%; Al2O3 in an amount such that the MgO / Al2O3 weight ratio is 2.4-6.6; 0.1% < Y2O3; CeO2 < 10%; and less than 0.6% of other oxides. In particular, it also relates to uses as an abrasive, a dispersant for moist media, a proppant, a heat exchanger, or for surface treatment.

[0015] Saint-Gobain European Design Research Centre CN101573307A relates to molten ceramic particles characterized by having the following chemical composition, expressed as a percentage by weight of oxides, totaling 100%: 55% < ZrO2 + HfO2 < 70%; 20% < SiO2 < 30%; 6.5% < MgO < 9.5%; the amount of Al2O3 such that the MgO / Al2O3 mass ratio is 2.4–6.6; and less than 0.6% of other oxides.

[0016] CN1108228A This invention relates to molten ceramic balls having the following chemical composition, expressed as a percentage by weight (based on the weight of oxides): 40-95% ZrO2 and HfO2; at least one Y2O3 and CeO2, provided that Y2O3 (in presence) accounts for 0.1-10%, CeO2 (in presence) accounts for 1-15%, and the total amount of Y2O3 and CeO2 is 0.1-25%; when CeO2 is absent, the amount of SiO2 accounts for 10-45% of the composition; when the composition contains CeO2, the amount of SiO2 accounts for 0.5-45% of the composition. The molten ceramic balls are used for grinding and dispersion in a wet medium. Summary of the Invention

[0017] This invention provides a novel type of molten ceramic particles, particularly molten ceramic particles in bead form. In the prior art, molten droplets exhibit precipitation spots during the cooling process. These precipitation spots do not significantly affect the physicochemical properties of the molten ceramic particles themselves, but when used for polishing, they require pre-polishing for more than 24 hours; otherwise, a stable polishing effect cannot be achieved, severely impacting product usability. The applicant has repeatedly attempted to adjust cooling parameters and material composition to reduce the occurrence of precipitation spots, but has been unable to completely eliminate them. The applicant has accidentally discovered that adding a small amount of scandium oxide to the raw materials can effectively reduce, or even completely remove, the precipitation spots on the surface of the spheres, thereby effectively stabilizing the polishing loss of the zirconium beads. Furthermore, the polished zirconium beads do not require pre-polishing before use; after purchase, they can be used after simple cleaning or washing, significantly improving product performance and work efficiency.

[0018] A zirconia composite ceramic microsphere, the raw material containing, by weight percentage:

[0019] 60% ≤ ZrO2 + HfO2 ≤ 65%;

[0020] 15% ≤ SiO2 ≤ 19%;

[0021] 9 ≤ Al2O3 ≤ 12%;

[0022] 2% ≤ CeO2 + Y2O3 ≤ 4;

[0023] 3% ≤ sodium hydroxide or sodium oxide ≤ 3.5%.

[0024] The zirconia composite ceramic microspheres are spherical spheres with a diameter of 80-100 μm, and the surface of the spheres is covered with precipitates of 200-300 nm, which are amorphous spots; the wear ratio of the zirconia composite ceramic microspheres is >1.82%.

[0025] When 3% ≤ Sc2O3 ≤ 5% by mass is added to the raw material, the surface precipitation spots disappear, and the wear ratio of the zirconia composite ceramic microspheres is < 0.72.

[0026] The mass ratio of CeO2 to Y2O3 in the raw materials is 1:(1-2).

[0027] The impurity content in the zirconia composite ceramic microspheres is ≤0.5% by mass.

[0028] A method for preparing molten zirconium oxide material includes the following steps:

[0029] (1) Mixing: The raw materials ZrO2+HfO2, SiO2, Al2O3, CeO2, Y2O3 and Sc2O3, as well as sodium hydroxide or sodium oxide, are mixed in a mass ratio and then added to a V-shaped mixer and mixed evenly.

[0030] (2) Melting: The mixture obtained in step (1) is placed in a three-phase electric arc furnace and melted using a voltage of 120-160V. After the mixture is melted, it is melted for another 25-30 minutes.

[0031] (3) Blowing: High-pressure air from an ejector is used to blow the molten mixture into a fine mist of small molten droplets;

[0032] (4) Cooling: The liquid droplets are cooled at 100-120℃ through water-cooled walls and cold air ducts;

[0033] (5) Screening: The cooled molten particles are screened on a vibrating bed to obtain spherical particles with a diameter of 80-100μm.

[0034] The raw materials, by weight percentage, contain: 60% ≤ ZrO2 + HfO2 ≤ 65%, 15% ≤ SiO2 ≤ 19%, 9% ≤ Al2O3 ≤ 12%, and 2% ≤ CeO2 + Y2O3 ≤ 4%.

[0035] 3% ≤ sodium hydroxide or sodium oxide ≤ 3.5% and 3% ≤ Sc2O3 ≤ 5%.

[0036] The zirconia molten material is used in the polishing field. The surface of the zirconia molten material is free of precipitation spots, and the wear ratio of the zirconia molten material is <0.72.

[0037] Beneficial technical effects: (1) The zirconia microspheres prepared by this invention have good roundness and relatively uniform size. (2) The surface of the zirconia microspheres is smooth, without obvious impurities or precipitation spots, with small polishing loss and good polishing effect. The samples can be directly polished without additional processes. Attached Figure Description

[0038] Appendix Figure 1 Optical image of the microbeads in Comparative Example 1 of this invention.

[0039] Appendix Figure 2 Optical image of the microbeads in Comparative Example 1 of this invention.

[0040] Appendix Figure 3 A magnified optical image of the microbeads in Comparative Example 1 of this invention.

[0041] Appendix Figure 4 A magnified optical image of the microbeads in Comparative Example 1 of this invention.

[0042] Appendix Figure 5 Optical image of the microbeads in Embodiment 2 of the present invention.

[0043] Appendix Figure 6 A magnified optical image of the microbeads in Embodiment 2 of the present invention.

[0044] Appendix Figure 7 The continuous wear test of Embodiment 2 and Comparative Example 1 of the present invention. Detailed Implementation

[0045] The processes for preparing microbeads in Examples 1-3 and the comparative examples of this invention are essentially the same, the only difference being whether or not scandium oxide is added.

[0046] The preparation process includes the following steps.

[0047] (1) Mixing: The raw materials ZrO2+HfO2, SiO2, Al2O3, CeO2, Y2O3 and Sc2O3, as well as sodium hydroxide or sodium oxide, are mixed in a mass ratio and then added to a V-shaped mixer and mixed evenly.

[0048] (2) Melting: The mixture obtained in step (1) is placed in a three-phase electric arc furnace and melted using a voltage of 120-160V. After the mixture is melted, it is melted for another 25-30 minutes.

[0049] (3) Blowing: High-pressure air from an injector is used to blow the molten mixture into a fine mist of small molten droplets.

[0050] (4) Cooling: via water-cooled walls and cold air ducts

[0051] The droplets are cooled at 100-120℃.

[0052] (5) Screening: The cooled molten particles are screened on a vibrating bed to obtain spherical particles with a diameter of 80-100μm. Example 1

[0053] A zirconia composite ceramic microsphere, the raw material containing, by weight percentage:

[0054] ZrO2+HfO263%.

[0055] SiO2 15.6%.

[0056] Al2O3 12.1%.

[0057] CeO2 + Y2O3 2.5%, with a mass ratio of CeO2 to Y2O3 of 1:1.

[0058] Sodium hydroxide or sodium oxide 3.5%.

[0059] Sc2O 33%.

[0060] Minor impurities. Example 2

[0061] A zirconia composite ceramic microsphere, the raw material containing, by weight percentage:

[0062] ZrO2 + HfO2 64%.

[0063] SiO2 16.3%.

[0064] Al2O3 9.8%.

[0065] CeO2 + Y2O3 2.7%, with a mass ratio of CeO2 to Y2O3 of 1:1.5.

[0066] Sodium hydroxide or sodium oxide 3.2%.

[0067] Sc2O34%.

[0068] Minor impurities. Example 3

[0069] A zirconia composite ceramic microsphere, the raw material containing, by weight percentage:

[0070] ZrO2 + HfO2 65%.

[0071] SiO2 15.1%.

[0072] Al2O3 9.2%.

[0073] CeO2 + Y2O3 2.5%, with a mass ratio of CeO2 to Y2O3 of 1:2.

[0074] Sodium hydroxide or sodium oxide 3.1%.

[0075] Sc2O 35%.

[0076] Minor impurities.

[0077] Comparative Example 1.

[0078] A zirconia composite ceramic microsphere, the raw material containing, by weight percentage:

[0079] ZrO2 + HfO2 64%.

[0080] SiO2 16.3%.

[0081] Al2O3 9.8%.

[0082] CeO2 + Y2O3 2.7%, with a mass ratio of CeO2 to Y2O3 of 1:1.5.

[0083] Sodium hydroxide or sodium oxide 3.2%.

[0084] Minor impurities.

[0085] First, the surface smoothness of the microspheres obtained in Example 2 and Comparative Example 1 was tested, see Appendix. Figure 1 Appendix Figure 2 As can be seen, when scandium oxide is absent, the surface has numerous precipitate spots and is not smooth; see appendix. Figure 3 and attached Figure 4 It is visible that the surface of the spheres has precipitates of 200-300 nm in size, which are amorphous and resemble an octagon. See Appendix. Figure 5 and attached Figure 6 It can be seen that when a small amount of scandium oxide is added, the surface is smooth and the zirconia composite ceramic microspheres are spherical with a diameter of 71.63 μm.

[0086] The wear ratio was tested using test method CN110642619A: 1 liter (apparent volume) of test beads was filled into a horizontal pressure mill with a capacity of 1.2 liters, i.e., a filling level of 83.3%. An agitator component was formed from a metal disc eccentrically positioned relative to the rotation axis and rotated at 2750 rpm, i.e., a disc peripheral speed of 10 m / s. The suspension to be ground was a 60% concentration of zirconium oxide powder in water, i.e., 6 kg of powder per 4 kg of water. This suspension was pumped through the mill at a flow rate of 6 L / h using a peristaltic pump. The test lasted for 1.5 hours. Once the test was completed, the beads were removed from the mill, cleaned, and dried.

[0087] The wear ratio of Example 1 was 0.53%, that of Example 2 was 0.49%, that of Example 3 was 0.72%, and that of Comparative Example 1 was 1.82%. It can be seen that if the precipitated phase on the surface of the spheres can be reduced or completely removed, the stability of the microspheres will be significantly improved.

[0088]

[0089] The 24-hour wear rate of Example 2 and Comparative Example 1 was tested, and the parameters were plotted as shown in the attached figure. Figure 7 As shown, in Example 2, there was almost no noticeable wear after about 2 hours, and the wear stabilized at 0.53-0.55%, while in Comparative Example 1, it took 6 hours to obtain a relatively stable amount of wear.

[0090] Physicochemical tests were performed on the microspheres obtained in Example 2 and Comparative Example 1: The microspheres obtained in Example 2 had a hardness of 65 HRC and a bulk density of 2.41 g / cm³. 3 The microspheres obtained in Comparative Example 1 had a hardness of 61 HRC and a bulk density of 2.29 g / cm³. 3 This indicates that scandium oxide also makes a certain technical contribution to the hardness of microspheres.

[0091] It must be pointed out that other undescribed technologies in this invention are well-known in the field, and those skilled in the art can find relevant literature describing them based on the names or functions described in this invention; therefore, they are not further described. The technical means disclosed in this invention are not limited to those disclosed in the above embodiments, but also include technical solutions composed of any combination of the above technical features.

Claims

1. A zirconia composite ceramic microsphere, wherein the zirconia composite ceramic microsphere is prepared by a melt method, characterized in that... The raw materials contain, by weight percentage: 60% ≤ ZrO2 + HfO2 ≤ 65%; 15% ≤ SiO2 ≤ 19%; 9 ≤ Al2O3 ≤ 12%; 2% ≤ CeO2 + Y2O3 ≤ 4%; 3% ≤ sodium hydroxide or sodium oxide ≤ 3.5%; When 3% ≤ Sc2O3 ≤ 5% by mass is added to the above raw materials, the surface precipitation spots disappear and the wear ratio of zirconia composite ceramic microspheres is < 0.

72.

2. The zirconia composite ceramic microspheres as described in claim 1, characterized in that... The zirconia composite ceramic microspheres are spherical spheres with a diameter of 80-100 μm.

3. The zirconia composite ceramic microspheres as described in claim 1, characterized in that... The mass ratio of CeO2 to Y2O3 in the raw materials is 1:(1-2).

4. The zirconia composite ceramic microspheres as described in claim 1, characterized in that... The impurity content in the zirconia composite ceramic microspheres is ≤0.5% by mass.

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