Experimental Investigation of Zirconia Powder Particle Size in Various Grinding Processes

To study the effect of different grinding equipment and grinding process parameters on the dispersion of powder aggregates, zirconia oxide powder with d50=1.355μm was chosen as the research material. The study aimed to examine the influence of grinding equipment and process parameters on the particle size of zirconia oxide slurry. Initially, vertical ball mills, vertical bead mills, and horizontal sand mills were employed as grinding equipment. 2mm zirconia beads were used as the grinding medium, and a medium-to-material ratio of 5:1 was maintained during 15 hours of grinding. The particle size of the zirconia oxide slurry was measured after grinding. The results revealed that the horizontal sand mill provided the best grinding effect, with a d50 value of 0.303μm for the zirconia oxide slurry.

Subsequently, the horizontal sand mill was chosen as the grinding equipment, and 2mm zirconia beads were used as the grinding medium. The study factors included the medium-to-material ratio, slurry solid content, linear velocity, and grinding time, each at three levels. A four-factor, three-level orthogonal experimental design (medium-to-material ratio of 4:1, 5:1, and 6:1; slurry solid content of 35%, 45%, and 55%; linear velocity of 5 m/s, 10 m/s, and 15 m/s; and grinding time of 20h, 25h, and 30h) was employed to investigate the particle size of the zirconia oxide slurry after grinding. The results indicated that, when using the horizontal sand mill as the grinding equipment with a medium-to-material ratio of 4:1, slurry solid content of 45%, linear velocity of 10 m/s, and grinding time of 25h, the best grinding effect was achieved, with a d50 value of approximately 0.3μm.

Nanopowders are widely used in high-performance ceramic materials. However, nanopowders often suffer from severe aggregation, which can impact their performance. To address powder aggregation issues, two main methods are typically employed. One approach involves controlling the formation of aggregates, such as using hydrothermal methods, sol-gel processes, or adding dispersants and solvent dehydration in precipitation systems. However, this method can be complex, increasing production costs and time. The other approach is to mechanically grind and disperse the aggregates after they have formed. Common grinding equipment used in industry includes horizontal sand mills, vertical bead mills, and ball mills.

In this study, different grinding equipment and grinding process parameters were investigated for their effect on the dispersion of powder aggregates using zirconia oxide powder with d50=1.355μm. Initially, different grinding equipment was compared under the same grinding conditions to determine the optimal equipment. Subsequently, the chosen equipment was used, and a four-factor, three-level orthogonal experimental design was implemented to determine the best grinding process parameters.

Experimental Procedure:

The zirconia oxide was prepared using a coprecipitation method. The d50 and d90 of the original zirconia oxide powder were found to be 1.355μm and 9.440μm, respectively. Different grinding equipment (vertical ball mills, vertical bead mills, and horizontal sand mills) were used with 2mm zirconia beads as grinding media (medium-to-material ratio of 5:1) and pure water as the dispersion medium (slurry solid content of 45%). After 15 hours of grinding, the particle size distribution of the resulting slurry was measured using a Bettersize2000 laser particle size analyzer to determine the optimal grinding equipment.

The horizontal sand mill was chosen as the optimal equipment, and a four-factor, three-level orthogonal experimental design was carried out using medium-to-material ratio, slurry solid content, linear velocity, and grinding time. The results showed that grinding time had the most significant impact on the grinding effect, followed by linear velocity, with the other factors having relatively smaller effects. The best combination, according to particle size and difference analysis, was determined to be a medium-to-material ratio of 4:1, slurry solid content of 45%, linear velocity of 10 m/s, and grinding time of 25 hours.

Conclusion:

1. The horizontal sand mill yielded the best grinding effect, with a d50 of 0.303μm for the zirconia oxide slurry.

2. Using the horizontal sand mill as the grinding equipment with a medium-to-material ratio of 4:1, slurry solid content of 45%, linear velocity of 10 m/s, and grinding time of 25 hours, the best grinding effect was achieved, with a d50 of approximately 0.3μm.