White corundum refers to aluminum oxide, and emery refers to silicon carbide.

White corundum: It is made from high-quality aluminum oxide powder by electric smelting. It has white color, high hardness, slightly low toughness, high purity, excellent self-sharpening and grindability. It has the characteristics of strong strength, low calorific value, high efficiency, resistance to acid and alkali corrosion, high temperature resistance, and good thermal stability

Silicon carbide is commonly known as emery, chemical formula SiC, colorless crystal, and appears blue-black when containing impurities. The structure is similar to diamond. Each silicon atom is surrounded by 4 carbon atoms, and each carbon atom is surrounded by 4 silicon atoms, forming a "giant molecule". The hardness is second only to diamond, the density is 3.217 g/cm3, and the melting point is about 2700°C (decomposition and sublimation). Chemically stable, it does not react with chlorine, oxygen, sulfur, or strong acids at high temperatures, but it can react with alkali.