... . C) refractive index: e = 1.760 w = 1.768 (Na line) resistivity: 30 C 300 C 900 C 1600 C (cm ... temperature resistance, corrosion resistance, high strength, such as performance, so use pouring steel slide gate, smelting rare metals, special alloy, ceramics ... , reduce brown corundum of residual carbon content, and make product in use not pulverization, not burst and great toughness is abrasives industry ...