Impact of Milling Equipment and Process Parameters on Zirconia Powder Particle Size

The Impact of Different Milling Equipment

In this study, we focus on the influence of different milling equipment and process parameters on the dispersion of zirconia nanoparticles with a d50 of 1.355 μm. Initially, we used vertical ball mills, vertical bead mills, and horizontal sand mills as milling equipment. 2 mm zirconia balls were used as the grinding medium at a medium-to-material ratio (m medium∶m material) of 5∶1, and the milling was carried out for 15 hours to assess the effect on zirconia slurry particle size.

The results revealed that the horizontal sand mill provided the best milling performance, with a post-milling zirconia slurry d50 of 0.303 μm. Therefore, we selected the horizontal sand mill as the optimal milling equipment for subsequent experiments.

Investigating the Impact of Milling Process Parameters

With the horizontal sand mill as our selected equipment, we further explored the effect of various process parameters on zirconia slurry particle size. Four factors were considered: medium-to-material ratio (m medium∶m material), slurry solid content (w), linear velocity, and milling time. Each factor was tested at three different levels. An orthogonal test (L9(34)) was conducted to optimize the milling process parameters.

Factors and Levels:

• Medium-to-material ratio (m medium∶m material): 4∶1, 5∶1, 6∶1

• Slurry solid content (w): 35%, 45%, 55%

• Linear velocity: 5 m·s^-1, 10 m·s^-1, 15 m·s^-1

• Milling time: 20 hours, 25 hours, 30 hours

The results indicated that the milling time had the most significant impact on milling efficiency, followed by linear velocity, while the other two factors had a comparatively smaller influence. Based on the particle size analysis and differential analysis, the ideal combination was determined to be A1B2C2D2, where the medium-to-material ratio (m medium∶m material) was 4∶1, slurry solid content (w) was 45%, linear velocity was 10 m·s^-1, and milling time was 25 hours.

Validation of Optimal Parameters

The optimal combination A1B2C2D2 was subjected to three validation tests, resulting in particle sizes of 0.309 μm, 0.312 μm, and 0.310 μm, with an average value of 0.310 μm. This indicates that the chosen optimal process parameters were not only reasonable but also exhibited good repeatability. The results closely align with the data from the second orthogonal test, which yielded a particle size of 0.305 μm, further validating the selected process parameters.

Conclusion

1. Among the milling equipment tested, the horizontal sand mill provided the best milling performance, with a post-milling zirconia slurry d50 of 0.303 μm.

2. When using the horizontal sand mill as the milling equipment and setting the medium-to-material ratio (m medium∶m material) to 4∶1, slurry solid content (w) to 45%, linear velocity to 10 m·s^-1, and milling time to 25 hours, optimal milling performance was achieved, resulting in a zirconia slurry d50 of approximately 0.3 μm.

In conclusion, selecting appropriate milling equipment and optimizing the milling process parameters can significantly impact the dispersion of zirconia powder, which is crucial for various industrial applications. The findings of this study provide valuable insights for achieving desired particle sizes and enhancing the efficiency of ceramic material processing.