The effect of the addition of flux on the wear resistance of ceramic balls can be seen in comparison with the use of natural minerals as fluxing agents (ie adding fluxes in a solid phase) compared to the addition of fluxes to ceramic balls prepared in the liquid phase. The firing temperature is reduced by 15e, and the fired porcelain balls have better wear resistance at the optimum firing temperature. This is due to the fact that when the flux is added in the liquid phase, the dispersed and finely-distributed flux crystals are precipitated from the powder in the drying and low-temperature sintering stages, and the distribution in the powder is more uniform than in the solid phase. . During the high-temperature sintering process, the uniformly distributed fine flux crystals on the one hand tend to form a liquid phase at a lower temperature, causing the green body to be sintered at a lower temperature, and on the other hand, the liquid phase is homogeneous in the green body. The distribution causes the grain boundary phase to precipitate uniformly between the main crystal phases, so that the bond between the grain boundaries is stronger, and the ratio of the transgranular fracture of the porcelain ball in the wear process is increased, so the wear resistance is better.
The effect of the ball milling time of the waste on the firing and abrasion resistance of the ceramic ball is the relationship between the characteristic grain size parameters of the waste and the ball milling time. It can be seen that as the ball milling time is extended, the particle size distribution of the waste material becomes narrower and the particles are refined. The grain size of the waste material rapidly decreases at the beginning, and the ball milling time does not change much after 24 hours, and finally stabilizes.
The influence of ball milling time on firing temperature and wear rate of ceramic ball can be seen. The wear rate of ceramic ball decreases first and then increases with the increase of firing temperature. In the firing process, on the one hand, the small pores migrate to the atmospheric pores or are discharged through the grain boundary diffusion. On the other hand, the crystal grains grow quickly and the ambassador shrinks locally to form closed pores. After the ceramic ball reaches the sintering temperature, the temperature continues to increase. The gas pressure in the closed-end hole increases rapidly to increase the pore size and porosity, and the wear resistance of the ceramic ball decreases. The wear rate can be a comprehensive measure of the mechanical properties of the ceramic ball, so the firing temperature corresponding to the lowest wear rate is the best firing temperature of the porcelain ball. It shows that the optimal firing temperature of ceramic ball decreases with the time of scrap ball milling, and the surface energy is one of the driving forces for particle sintering. If the particle size is too large, the surface energy of the particle chromatograph is low, it is difficult to form a liquid phase at a low temperature, and solid phase diffusion is difficult, so the firing temperature is high. As the milling time increases, the particle size of the waste material gradually decreases, the surface energy and the surface activity of the particles increase, the liquid phase can be formed at a lower temperature, and the higher the particle migration speed and the shorter diffusion distance during sintering, Helps the ceramic ball to complete sintering densification at lower temperatures. It can be seen from the above that, as the scrap ball milling time is extended, the wear resistance of the porcelain ball is gradually increased. Ceramic grain size, structure, pore size and number will affect the ceramic ball wear behavior and wear resistance. The smaller the grain, the better the resistance of the porcelain ball. As the grain size increases, wear transitions from deformation-controlled mild wear to severe wear controlled by microfracture. Among them, large-grained grains are related to wear. Ceramics have a low porosity, a small pore size, and a high wear resistance. It shows that the maximum particle size and large particle content of the waste materials decrease rapidly with the extension of ball milling time. The smaller particle size of the waste material and the lower firing temperature make the ceramics form a fine-grained microstructure structure, thereby increasing the wear resistance of the ceramic balls. From the SEM micrographs, the average grain size of the ceramic balls prepared by ball milling at 6h, 24h, and 72h was 10Lm, 56Lm, and 34Lm, and the porosity was about 8%, 1%, and 1%, respectively. The diameter is about 10Lm, 34Lm and 2Lm, ie, the grain size, porosity, and pore diameter of the porcelain ball decrease with the prolongation of the scrap ball milling time (ie, the reduction of the scrap particle size), so the wear resistance of the porcelain ball is increased.
The effect of the forming pressure of the ball blank on the wear resistance of the prepared ceramic ball shows that the wear rate of the ceramic ball fired at the same temperature within the firing temperature range decreases as the forming pressure of the blank increases, ie, the ball The wear resistance increases as the forming pressure of the blank increases. The SEM micrographs of the microstructure show that the porosity and pore diameter in the ceramic balls formed under the pressure of 65 MPa are significantly larger than those of the porcelain balls formed under the pressure of 150 MPa. Pores are an internal defect of the porcelain ball, which will make the ceramic ball more likely to produce grain exfoliation and cracking during the wear process, thereby greatly reducing its wear resistance. When the molding pressure is low, there are many macropores whose pore diameters are greater than 10 times the diameter of the powder particles and coarse micropores with pore diameters between the 1/2 particle diameter and macroscopic macropores. In the sintering process, the macro macro pores have almost the same shrinkage rate as the green body, so the porosity rate caused by the micro macro pores does not change, and the coarse micro pores do not change or slightly grow during sintering, so the pore size and pores in the ceramic spheres The rates are large. As the molding pressure increases, both the pore size and the porosity decrease, so that the wear resistance of the ceramic ball is improved.
Conclusions (1) Aluminosilicate refractory waste can be recycled to produce green grinding media with excellent performance. (2) Compared with the use of non-soluble fluxes, ceramic balls prepared with soluble fluxes have low firing temperatures and high wear resistance. (3) Improve the forming pressure of the blank, the porosity of the ceramic ball decreases, the pore size decreases, and the wear resistance increases.
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