Which Is Better, White Granules Or White Powder?

High-purity α-Al₂O₃ is a high-performance key raw material with high hardness, low impurities, and sharp particle morphology, obtained through electric arc furnace melting, rapid cooling, crushing, and grading. Due to its special properties, it is also frequently used as a primary raw material for grinding wheels, polishing pastes, sandblasting, and ultra-fine grinding.

Because white fused alumina products contain high Al₂O₃ and low impurities, they reduce workpiece surface contamination and improve sintering consistency and thermal conductivity during processing. The narrow PSD and controllable particle morphology also allow for predictable grinding wheel porosity and wear behavior during processing. Currently, white fused alumina abrasives are commonly used, mostly as raw materials for ceramic grinding wheels, with grit sizes ranging from medium-coarse to medium-fine (#36–#150) for different processing states from coarse to semi-fine grinding. Polishing pastes generally use micronized (D50 <10 μm) white fused aluminum oxide, primarily for mirror polishing and ultra-fine grinding.

Unlike white fused alumina in its normal form, white fused alumina micropowder is an ultrafine abrasive. It is generally preferred for surface treatment applications due to its high hardness, chemical inertness, and controllable particle size distribution, particularly for polishing, surface coating filling, micro-grinding, and precision surface finishing.

Furthermore, white fused alumina in its micropowder state typically has multiple angular edges to maintain machinability or a near-spherical shape to facilitate filler applications. Especially in the case of optical/electronic ultra-fine polishing, white fused alumina micropowder typically has a D50 of 0.1–0.5 µm, requiring extremely low soluble ions and minimal powdering. Functional coating fillers/grinding slurries typically have a D50 of 0.5–2 µm because uniform PSD and a suitable specific surface area facilitate dispersion. Finally, considering the balance between wear rate and cost, surface finishing and deburring generally achieve a D50 of 2–8 µm.