Ceramic polishing sand and method of making same

Abstract

The application belongs to the technical field of ceramic sand preparation, and particularly relates to a ceramic polishing sand and a preparation method thereof. The ceramic polishing sand is composed of the following raw materials: zirconium oxide, white corundum, coke spar, lithium tetraborate, di-niobium pentoxide, strontium zirconate, cerium hexaboride, nano-magnesium oxide, a binder and a dispersing agent. The ceramic polishing sand takes zirconium oxide as a main crystal phase, provides basic hardness and wear resistance for the ceramic polishing sand, and further enhances the hardness and cutting performance of the ceramic polishing sand by using white corundum; the mixture of coke spar, lithium tetraborate, di-niobium pentoxide, strontium zirconate, cerium hexaboride and nano-magnesium oxide is used as a ceramic modifier to improve the compactness, mechanical strength of the ceramic polishing sand and reduce the sintering temperature during the sintering process. In addition, the binder and the dispersing agent are added, and the raw materials synergistically act to ensure that the prepared ceramic polishing sand has excellent fracture toughness, single-particle compressive strength and Vickers hardness.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of ceramic sand preparation, and particularly relates to a ceramic polishing sand and a preparation method thereof. BACKGROUND

[0002] The ceramic polishing sand is also called ceramic sand or ceramic shot, and is a composite material of zirconium oxide and silicon oxide. The ceramic polishing sand has very good wear resistance and impact resistance, and has excellent strength and hardness. Compared with steel shot, iron shot and glass shot, the ceramic polishing sand has the characteristics of good environmental protection, low breakage rate, high hardness and small deformation. Therefore, the ceramic polishing sand is widely applied to surface finishing and surface strengthening treatment of various metal products such as aircraft turbine blades, gear hydraulic parts, stamping and grinding tools, machine pressure grinding tools and medical devices.

[0003] The main functions of the ceramic polishing sand are as follows: ① sand blasting cleaning: removing oxide skin, rust and old paint layer to provide a clean base for subsequent coating / electroplating; ② surface strengthening (shot peening strengthening): high-speed impact makes the metal surface layer produce plastic deformation to form a 'cold work hardening layer' to improve fatigue strength and wear resistance; ③ precision polishing / matting finishing: controlling roughness, eliminating burrs and performing matte or mirror surface pretreatment; ④ improving coating adhesion: improving coating bonding strength through micro-roughening surface; and ⑤ mold maintenance: cleaning residual dirt and slight cracks to prolong the service life of the mold.

[0004] At present, with the development of industrialization in China, the requirements for product surface performance are continuously improved in various industries, and the application of the ceramic polishing sand is further developed. However, in some high-end manufacturing fields, the traditional ceramic polishing sand has the defect of insufficient mechanical properties. The performance bottleneck of the traditional ceramic polishing sand mainly comes from two aspects: one is the limitation of material formula, and the simple combination of zirconium oxide and silicon oxide in the traditional formula is difficult to form an efficient microstructure; and the other is the imperfect preparation process, and the grain growth is not accurately controlled in the sintering process, so that the grain boundary bonding force is weak. Some improvement attempts such as adding ordinary sintering aids (such as boron glass, clay, etc.) can improve the sintering activity to a certain extent, but often introduce new problems such as reduced hardness. Therefore, it is necessary to explore a new type of ceramic polishing sand. SUMMARY

[0005] The application aims to provide a ceramic polishing sand which has excellent Vickers hardness and single particle compressive strength, and further provides a preparation method thereof.

[0006] The ceramic polishing sand comprises the following raw materials in parts by weight: 80-81 parts of zirconium oxide, 5.5-6.92 parts of white corundum, 6.8-7.0 parts of coke, 1.8-2.0 parts of lithium tetraborate, 0.6-0.7 parts of niobium pentoxide, 0.6-0.8 parts of strontium zirconate, 1.1-1.2 parts of cerium hexaboride, 0.38-0.40 parts of nano-magnesium oxide, 1.0-1.2 parts of a binder, and 0.5 parts of a dispersant.

[0007] The binder is a mixture of polyvinyl alcohol and aluminum sol, and the mass ratio of polyvinyl alcohol to aluminum sol is 1:2.

[0008] The dispersant is a mixture of citric acid and sodium hexametaphosphate, and the mass ratio of citric acid to sodium hexametaphosphate is 2:1.

[0009] The preparation method of the ceramic polishing sand comprises the following steps:

[0010] (1) uniformly mixing zirconium oxide, white corundum, coke, lithium tetraborate, niobium pentoxide, strontium zirconate, cerium hexaboride, nano-magnesium oxide, and a binder, and then adding a dispersant for further ball milling to prepare a mixture;

[0011] (2) spray drying and granulating the mixture prepared in step (1) to prepare a green body;

[0012] (3) sintering the green body prepared in step (2) in an air atmosphere, wherein the sintering is first heating at a heating rate of 3 ℃ / min to 590-600 ℃ for 1 h, then heating at a heating rate of 2 ℃ / min to 1050-1100 ℃ for 20 min, and finally heating at a heating rate of 5 ℃ / min to 1200-1250 ℃ for 1.5 h;

[0013] (4) after sintering, first cooling at a cooling rate of 3 ℃ / min to 900-910 ℃ for 1 h, then cooling at a cooling rate of 5 ℃ / min to 400 ℃, and finally naturally cooling to room temperature for post-processing to prepare the ceramic polishing sand.

[0014] In step (1), the ball milling speed is 200 r / min during the first wet ball milling, and the ball milling time is 2.5-2.7 h; during the further ball milling, the ball milling speed is 200 r / min, and the ball milling time is 0.5 h.

[0015] In step (1), water is added during the first wet ball milling, and the mass ratio of zirconium oxide, white corundum, coke, lithium tetraborate, niobium pentoxide, strontium zirconate, cerium hexaboride, nano-magnesium oxide, and the binder to water is 1:0.50.

[0016] The inlet air temperature of the spray drying in step (2) is 230 DEG C, and the outlet air temperature of the spray drying is 110 DEG C.

[0017] The pressure of the dry pressing in step (2) is 180 MPa, and the pressure maintaining time is 30 s.

[0018] The post-treatment in step (4) is ultrasonic cleaning in water for 10 min, drying at 108-110 DEG C for 30 min, and finally grading and sieving to prepare the ceramic polishing sand; the grading and sieving is that the dried material is graded and sieved by a standard sieve, that is, the material is firstly sieved through a 100-mesh sieve, the sieve residue is discarded, the sieve residue is then sieved through a 150-mesh sieve, the sieve residue of the 150-mesh sieve is collected as the ceramic polishing sand, and the sieve residue is discarded.

[0019] Compared with the prior art, the present application has the following beneficial effects:

[0020] (1) The ceramic polishing sand provided by the present application uses zirconia as the main crystal phase to provide the basic hardness and wear resistance of the ceramic polishing sand, and white corundum further enhances the hardness and cutting performance of the ceramic polishing sand; the mixture of flint, lithium tetraborate, niobium pentoxide, strontium zirconate, cerium hexaboride and nano-magnesium oxide is used as the ceramic modifier to improve the density, mechanical strength and reduce the sintering temperature of the ceramic polishing sand during sintering; the mixture of polyvinyl alcohol and aluminum sol is used as the binder, and the mixture of citric acid and sodium hexametaphosphate is used as the dispersant, so that the raw materials synergistically act to ensure that the prepared ceramic polishing sand has excellent fracture toughness, single-particle compressive strength and Vickers hardness.

[0021] (2) The ceramic polishing sand provided by the present application uses the mixture of flint, lithium tetraborate, niobium pentoxide, strontium zirconate, cerium hexaboride and nano-magnesium oxide as the ceramic modifier, wherein the flint is the main raw material of the binder, generates an aluminum-silicon-rich glass phase in situ by high-temperature sintering, fills the pores, and at the same time, a small amount of mullite phase is generated by the reaction of part of the components, forming a "glass-microcrystalline" composite skeleton, which significantly improves the density of the ceramic polishing sand and thus enhances the mechanical strength of the ceramic polishing sand; lithium tetraborate is used as the main sintering aid to form a low-viscosity boron-lithium glass phase at a relatively low temperature, realizing low-temperature rapid densification; the Nb 5+ of niobium pentoxide is partially solid-solved into the zirconia lattice to form point defects, which inhibit the grain boundary migration and grain growth, and the released Ce 4+Synergistic effect, effectively reduce the grain size, improve the grain boundary bonding strength; strontium zirconate as perovskite structure of inert hard phase, its thermal expansion coefficient and zirconia are highly matched, when impacted, can consume impact energy through the "crack deflection / bridge" effect, significantly improve the impact resistance of ceramic polishing sand; cerium hexaboride decomposes to form cerium oxide and boron oxide during high temperature sintering, among which the boron oxide and lithium tetraborate form a low viscosity liquid phase, promote densification, after cooling in the grain boundary to form glass phase, help to improve the grain boundary bonding strength. In addition, also added nano magnesium oxide, nano magnesium oxide and SiO2 in the jumboite reaction to form forsterite, as a grain boundary phase exists, at the same time play a role in part of the stable zirconia crystal phase. Thus, by adding ceramic modifier to further improve the mechanical strength of the prepared ceramic polishing sand.

[0022] (3) The ceramic polishing sand described in the application, a mixture of polyvinyl alcohol and aluminum sol as a binder, polyvinyl alcohol ensures the bonding strength of the green body of the ceramic polishing sand during dry pressing, and the aluminum sol is decomposed into alumina during high temperature sintering, which can react with SiO2 in the jumboite to generate a small amount of mullite phase, thereby helping to improve the fracture toughness. A mixture of citric acid and sodium hexametaphosphate as a dispersant, citric acid forms a chelation effect with ZrO2 / Al2O3 particle surface through carboxylate, while providing electrostatic repulsion; sodium hexametaphosphate is adsorbed on the surface of the particles through long chains, producing a steric hindrance effect; the two synergistically work together to effectively inhibit hard agglomeration and ensure the stability of the slurry during spray drying.

[0023] (4) The preparation method of the ceramic polishing sand described in the application, by means of segmented ball milling, spray granulation and segmented sintering, etc. to realize low temperature rapid densification, the performance of the prepared ceramic polishing sand is stable. DETAILED DESCRIPTION

[0024] Example 1

[0025] The ceramic polishing sand described in this embodiment 1, by weight parts, consists of: zirconia 80.5 parts, white corundum 6.21 parts, jumboite 6.9 parts, lithium tetraborate 1.9 parts, niobium pentoxide 0.65 parts, strontium zirconate 0.7 parts, cerium hexaboride 1.15 parts, nano magnesium oxide 0.39 parts, binder 1.1 parts, dispersant 0.5 parts.

[0026] Among them: the binder is a mixture of polyvinyl alcohol and aluminum sol, the mass ratio of polyvinyl alcohol to aluminum sol is 1:2.

[0027] The dispersant is a mixture of citric acid and sodium hexametaphosphate, the mass ratio of citric acid to sodium hexametaphosphate is 2:1.

[0028] The preparation method of the ceramic polishing sand described in this embodiment 1 consists of the following steps:

[0029] (1) zirconia, white corundum, coke, lithium tetraborate, niobium pentoxide, strontium zirconate, cerium hexaboride, nano-magnesium oxide and a binder are mixed uniformly for first wet ball milling, and then a dispersant is added for further ball milling to prepare a mixture;

[0030] (2) the mixture prepared in step (1) is prepared into a green body by spray drying and granulating and dry pressing;

[0031] (3) the green body prepared in step (2) is sintered in an air atmosphere, and the sintering is first heated to 595℃ at a heating rate of 3℃ / min for 1h, then heated to 1080℃ at a heating rate of 2℃ / min for 20min, and finally heated to 1230℃ at a heating rate of 5℃ / min for 1.5h;

[0032] (4) after sintering, it is first cooled to 905℃ at a cooling rate of 3℃ / min for 1h, then cooled to 400℃ at a cooling rate of 5℃ / min, and finally naturally cooled to room temperature for post-treatment to prepare a ceramic polishing sand.

[0033] In step (1), the first wet ball milling is carried out at a ball milling speed of 200r / min for 2.6h, and the further ball milling is carried out at a ball milling speed of 200r / min for 0.5h.

[0034] In step (1), water is added during the first wet ball milling, and the mass ratio of zirconia, white corundum, coke, lithium tetraborate, niobium pentoxide, strontium zirconate, cerium hexaboride, nano-magnesium oxide and the binder to water is 1:0.50.

[0035] In step (2), the inlet air temperature of the spray drying is 230℃, and the outlet air temperature of the spray drying is 110℃.

[0036] In step (2), the dry pressing is carried out at a pressure of 180MPa for 30s.

[0037] In step (4), the post-treatment is ultrasonic cleaning in water for 10min, drying at 109℃ for 30min, and finally grading and sieving to prepare a ceramic polishing sand, wherein the grading and sieving is that the dried material is graded and sieved by a standard sieve, i.e. first passing through a 100 mesh sieve, discarding the sieve upper material, and then passing the sieve lower material through a 150 mesh sieve, collecting the 150 mesh sieve upper material as the ceramic polishing sand, and discarding the sieve lower material.

[0038] Example 2

[0039] The ceramic polishing sand of the present embodiment 2 is composed of the following raw materials in parts by weight: zirconium oxide 80 parts, white corundum 6.92 parts, coke 6.80 parts, lithium tetraborate 1.8 parts, niobium pentoxide 0.7 parts, strontium zirconate 0.8 parts, cerium hexaboride 1.1 parts, nano-magnesium oxide 0.38 parts, binder 1.0 part, dispersant 0.5 part.

[0040] The binder is a mixture of polyvinyl alcohol and aluminum sol, and the mass ratio of polyvinyl alcohol to aluminum sol is 1:2.

[0041] The dispersant is a mixture of citric acid and sodium hexametaphosphate, and the mass ratio of citric acid to sodium hexametaphosphate is 2:1.

[0042] The preparation method of the ceramic polishing sand of the present embodiment 2 is composed of the following steps:

[0043] (1) The zirconium oxide, white corundum, coke, lithium tetraborate, niobium pentoxide, strontium zirconate, cerium hexaboride, nano-magnesium oxide, and binder are mixed uniformly for the first time wet ball milling, and then the dispersant is added for continuous ball milling to prepare a mixture;

[0044] (2) The mixture prepared in step (1) is prepared into a green body by spray drying and granulating, and dry pressing;

[0045] (3) The green body prepared in step (2) is sintered in an air atmosphere, and the sintering is first heated to 590°C at a heating rate of 3°C / min for 1h, then heated to 1050°C at a heating rate of 2°C / min for 20min, and finally heated to 1200°C at a heating rate of 5°C / min for 1.5h;

[0046] (4) After sintering is completed, first, the temperature is decreased to 900°C at a cooling rate of 3°C / min for 1h, then the temperature is decreased to 400°C at a cooling rate of 5°C / min, and finally the temperature is naturally cooled to room temperature for post-processing to prepare the ceramic polishing sand.

[0047] In step (1), the first time wet ball milling is at a ball milling speed of 200r / min for 2.5h, and the continuous ball milling is at a ball milling speed of 200r / min for 0.5h.

[0048] In step (1), water is added during the first time wet ball milling, and the mass ratio of the zirconium oxide, white corundum, coke, lithium tetraborate, niobium pentoxide, strontium zirconate, cerium hexaboride, nano-magnesium oxide, and binder to water is 1:0.50.

[0049] In step (2), the inlet air temperature of the spray drying is 230°C, and the outlet air temperature of the spray drying is 110°C.

[0050] The pressure of dry pressing in step (2) is 180 MPa, and the pressure holding time is 30 s.

[0051] The post-treatment in step (4) is ultrasonic cleaning in water for 10 min, drying at 108℃ for 30 min, and finally grading and sieving, to prepare the ceramic polishing sand, wherein the grading and sieving is that the dried material is graded and sieved by a standard sieve: first through a 100-mesh sieve, the sieve residue is discarded, the sieve residue is then passed through a 150-mesh sieve, the sieve residue of the 150-mesh sieve is collected as the ceramic polishing sand, and the sieve residue is discarded.

[0052] Example 3

[0053] The ceramic polishing sand in this example 3 is composed of the following raw materials in parts by weight: zirconia 81 parts, white corundum 5.5 parts, coke 7.0 parts, lithium tetraborate 2.0 parts, niobium pentoxide 0.6 parts, strontium zirconate 0.6 parts, cerium hexaboride 1.2 parts, nano-magnesium oxide 0.40 parts, binder 1.2 parts, and dispersant 0.5 parts.

[0054] The binder is a mixture of polyvinyl alcohol and aluminum sol, and the mass ratio of polyvinyl alcohol to aluminum sol is 1:2.

[0055] The dispersant is a mixture of citric acid and sodium hexametaphosphate, and the mass ratio of citric acid to sodium hexametaphosphate is 2:1.

[0056] The preparation method of the ceramic polishing sand in this example 3 is composed of the following steps:

[0057] (1) The zirconia, white corundum, coke, lithium tetraborate, niobium pentoxide, strontium zirconate, cerium hexaboride, nano-magnesium oxide, and binder are mixed uniformly for first-time wet ball milling, and then the dispersant is added for further ball milling, to prepare a mixture;

[0058] (2) The mixture prepared in step (1) is prepared into a green body by spray drying and granulation, and dry pressing;

[0059] (3) The green body prepared in step (2) is sintered in an air atmosphere, and the sintering is first heated to 600℃ at a heating rate of 3℃ / min and kept for 1 h, then heated to 1100℃ at a heating rate of 2℃ / min and kept for 20 min, and finally heated to 1250℃ at a heating rate of 5℃ / min and kept for 1.5 h;

[0060] (4) After sintering is completed, first, the temperature is decreased to 910℃ at a cooling rate of 3℃ / min and kept for 1 h, then the temperature is decreased to 400℃ at a cooling rate of 5℃ / min, and finally the temperature is naturally cooled to room temperature for post-treatment, to prepare the ceramic polishing sand.

[0061] The ball milling speed in the first wet ball milling in step (1) is 200 r / min, and the ball milling time is 2.7 h. When the ball milling is continued, the ball milling speed is 200 r / min, and the ball milling time is 0.5 h.

[0062] Water is added in the first wet ball milling in step (1), and the mass ratio of the zirconium oxide, white corundum, flint, lithium tetraborate, niobium pentoxide, strontium zirconate, cerium hexaboride, nano-magnesium oxide, and the binder to water is 1:0.50.

[0063] The inlet air temperature of the spray drying in step (2) is 230 ℃, and the outlet air temperature of the spray drying is 110 ℃.

[0064] The pressure of the dry pressing in step (2) is 180 MPa, and the pressure holding time is 30 s.

[0065] The post-treatment in step (4) is ultrasonic cleaning in water for 10 min, drying at 110 ℃ for 30 min, and finally grading and sieving to prepare the ceramic polishing sand. The grading and sieving is that the dried material is graded and sieved by a standard sieve, that is, first passing through a 100-mesh sieve, discarding the sieve upper material, and then passing through a 150-mesh sieve, collecting the 150-mesh sieve upper material as the ceramic polishing sand, and discarding the sieve lower material.

[0066] Comparative Example 1

[0067] The preparation method of the ceramic polishing sand in the present comparative example 1 is the same as that in Example 1, and the only difference is that the raw material composition is different. The ceramic polishing sand in the present comparative example 1 is composed of the following raw materials in parts by weight: zirconium oxide 80.5 parts, white corundum 6.21 parts, flint 6.9 parts, strontium zirconate 0.7 parts, nano-magnesium oxide 0.39 parts, binder 1.1 parts, and dispersant 0.5 parts.

[0068] The binder is a mixture of polyvinyl alcohol and aluminum sol, and the mass ratio of polyvinyl alcohol to aluminum sol is 1:2.

[0069] The dispersant is a mixture of citric acid and sodium hexametaphosphate, and the mass ratio of citric acid to sodium hexametaphosphate is 2:1.

[0070] Comparative Example 2

[0071] The preparation method of the ceramic polishing sand in the present comparative example 2 is the same as that in Example 1, and the only difference is that the raw material composition is different. The ceramic polishing sand in the present comparative example 2 is composed of the following raw materials in parts by weight: zirconium oxide 80.5 parts, white corundum 6.21 parts, lithium tetraborate 1.9 parts, niobium pentoxide 0.65 parts, strontium zirconate 0.7 parts, cerium hexaboride 1.15 parts, binder 1.1 parts, and dispersant 0.5 parts.

[0072] The binder is a mixture of polyvinyl alcohol and aluminum sol, and the mass ratio of polyvinyl alcohol to aluminum sol is 1:2.

[0073] The dispersant is a mixture of citric acid and sodium hexametaphosphate, and the mass ratio of citric acid to sodium hexametaphosphate is 2:1.

[0074] Comparative Example 3

[0075] The preparation method of the ceramic polishing sand in the present comparative example 3 is the same as that in Example 1, and the only difference is that the raw material composition is different. The ceramic polishing sand in the present comparative example 3 is composed of the following raw materials in parts by weight: zirconia 80.5 parts, white corundum 6.21 parts, flint 6.9 parts, lithium tetraborate 1.9 parts, niobium pentoxide 0.65 parts, cerium hexaboride 1.15 parts, nano-magnesium oxide 0.39 parts, binder 1.1 parts, and dispersant 0.5 parts.

[0076] The binder is a mixture of polyvinyl alcohol and aluminum sol, and the mass ratio of polyvinyl alcohol to aluminum sol is 1:2.

[0077] The dispersant is a mixture of citric acid and sodium hexametaphosphate, and the mass ratio of citric acid to sodium hexametaphosphate is 2:1.

[0078] The ceramic polishing sands prepared in Examples 1-3 and Comparative Examples 1-3 are subjected to performance tests, and the test results are shown in Table 1; wherein:

[0079] (1) The bulk density is tested according to GB / T 31057.2.

[0080] (2) The Vickers hardness is tested according to GB / T 4340.1.

[0081] (3) The fracture toughness is tested by the indentation method according to ASTM C1327.

[0082] (4) The test method for single particle compressive strength is as follows: 50 particles with regular shape and no obvious surface defects are randomly selected from the prepared ceramic polishing sand with a particle size range of 100-150 mesh, and are ultrasonically cleaned with absolute ethanol for 2 min and dried at 110°C; a micro-force testing machine equipped with a diamond flat indenter is used for testing, the indenter diameter is 0.3 mm, the loading rate is set to 0.5 N / s, the test environment temperature is 23°C, and the resolution of the device load sensor is 0.5 mN. A single particle is placed on the test platform, and the maximum load value F max (unit: N) at which the particle breaks under axial compression is recorded. Subsequently, the same particle is placed on the rotating platform of an optical microscope, and the projected diameters of the particle in three directions of 0°, 60° and 120° are measured respectively, and the arithmetic mean value is calculated as the characteristic diameter d avg(unit: mm). The calculation formula of single particle compressive strength is: σ = 4F max / (π × d avg 2 ), unit MPa.

[0083] (5) The test method of single breakage rate consists of the following steps:

[0084] ① Sample pretreatment: take 200 g of ceramic polishing sand sample (100 mesh < particle size ≤ 150 mesh) (recorded as total mass M) and place it in a 105°C oven for drying for 2 h, then take it out and cool it to room temperature in a desiccator. Use a 150 mesh standard sieve on a standard sieve shaker for 2 min to remove undersize (fine powder) and impurities.

[0085] ② Preparation of test sample: accurately weigh 100.00 g of the pretreated total sample using a one-hundredth electronic balance, and evenly divide the 100 g sample into 10 equal parts, each part weighing 10.00 g. The mass of each part is recorded as m0.

[0086] ③ Test preparation: calibrate the sandblasting pressure gauge, the nozzle diameter of the sandblasting gun is 3 mm, fix the 45# steel plate target in the sealed sandblasting table, adjust the distance between the nozzle and the target to 100 mm and the included angle to 90°, and set the sandblasting pressure to 0.5 MPa.

[0087] ④ Single impact test and calculation: load one sample (10.00 g) into the sandblasting machine hopper, and use a constant sandblasting pressure (0.5 MPa) and nozzle diameter (3 mm) to blast all the sample at once, ensuring that all particles are impacted, and use a sealed collection box to collect all the impacted particles. Transfer all the recovered particles to a 200 mesh standard sieve and sieve for 2 min on a standard sieve shaker, weigh the mass of the oversize (intact particles that have not been broken), recorded as m i1 , and weigh the mass of the undersize (broken particles) m i2 . Verify that m0≈m i1 +m i2 (the error should be ≤1%). If the mass loss is too large, it indicates that the particles were not fully collected, and this test should be discarded and retested. Calculate the single breakage rate Xᵢ of this sample: Xᵢ= (m0-m i1 ) / m0 × 100%, where i is 1-10, representing the measurement order of the 10 samples.

[0088] ⑤ After all 10 samples have been tested, 10 single breakage rate data (X1, X2,..., X 10 ) are obtained. The final test result is the arithmetic mean of these 10 results: X= (X1+X2+...+X 10) / 10, the average value X is the single breakage rate of the batch of ceramic polishing sand, and the lower the value, the stronger the impact resistance of the sample.

[0089] Table 1 Performance test results of ceramic polishing sand

[0090]

[0091] As can be seen from Table 1, the performance of the ceramic polishing sand prepared in Examples 1-3 is obviously better than that of Comparative Examples 1-3. In Comparative Example 1, lithium tetraborate, niobium pentoxide and cerium hexaboride are not added, that is, sintering aids and grain refinement components are lacking, resulting in a decrease in comprehensive performance. In Comparative Example 2, calcined flint and nano magnesium oxide are lacking, that is, glass phase and mullite reinforcing phase are lacking, resulting in a decrease in single particle compressive strength and fracture toughness. In Comparative Example 3, strontium zirconate is lacking, that is, a toughening phase is lacking, resulting in a decrease in toughness.

Claims

1. A ceramic polishing grit, characterized by: The ceramic polishing sand is prepared from the following raw materials in parts by weight: zirconium oxide 80-81 parts, white corundum 5.5-6.92 parts, coke 6.8-7.0 parts, lithium tetraborate 1.8-2.0 parts, niobium pentoxide 0.6-0.7 parts, strontium zirconate 0.6-0.8 parts, cerium hexaboride 1.1-1.2 parts, nano-magnesium oxide 0.38-0.40 parts, a binder 1.0-1.2 parts, and a dispersant 0.5 parts; The binder is a mixture of polyvinyl alcohol and aluminum sol, and the mass ratio of polyvinyl alcohol to aluminum sol is 1:2; The dispersant is a mixture of citric acid and sodium hexametaphosphate, and the mass ratio of citric acid to sodium hexametaphosphate is 2:

1.

2. A method of producing the ceramic polishing grit of claim 1, characterized by: The ceramic polishing sand is prepared by the following steps: (1) mixing zirconium oxide, white corundum, coke, lithium tetraborate, niobium pentoxide, strontium zirconate, cerium hexaboride, nano-magnesium oxide, and the binder uniformly for first-time wet ball milling, then adding the dispersant for further ball milling to prepare a mixture; (2) preparing a green body by spray drying and granulating the mixture prepared in step (1) and dry pressing; (3) sintering the green body prepared in step (2) in an air atmosphere, wherein the sintering is first heating at a heating rate of 3 ℃ / min to 590-600 ℃ for 1 h, then heating at a heating rate of 2 ℃ / min to 1050-1100 ℃ for 20 min, and finally heating at a heating rate of 5 ℃ / min to 1200-1250 ℃ for 1.5 h; (4) after sintering, first cooling at a cooling rate of 3 ℃ / min to 900-910 ℃ for 1 h, then cooling at a cooling rate of 5 ℃ / min to 400 ℃, and finally naturally cooling to room temperature for post-treatment to prepare the ceramic polishing sand.

3. The method of claim 2, wherein: In step (1), the first-time wet ball milling is performed at a ball milling speed of 200 r / min for 2.5-2.7 h, and the further ball milling is performed at a ball milling speed of 200 r / min for 0.5 h.

4. The method of claim 2, wherein: In step (1), water is added during the first-time wet ball milling, and the mass ratio of zirconium oxide, white corundum, coke, lithium tetraborate, niobium pentoxide, strontium zirconate, cerium hexaboride, nano-magnesium oxide, and the binder to water is 1:0.

50.

5. The method of claim 2, wherein: In step (2), the inlet air temperature of the spray drying is 230 ℃, and the outlet air temperature of the spray drying is 110 ℃.

6. The method of claim 2, wherein: In step (2), the dry pressing is performed at a pressure of 180 MPa for 30 s.

7. The method for preparing ceramic polishing sand according to claim 2, characterized in that: In step (4), the post-treatment is ultrasonic cleaning in water for 10 min, drying at 108-110 ℃ for 30 min, and finally grading and sieving to prepare the ceramic polishing sand, wherein the grading and sieving is that the dried material is first sieved through a 100-mesh sieve, the sieve residue is discarded, the sieve residue is then sieved through a 150-mesh sieve, the sieve residue of the 150-mesh sieve is collected as the ceramic polishing sand, and the sieve residue is discarded.

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