俗名又稱金剛砂,是用礬土、碳素材料、鐵屑三種原料在電爐中經(jīng)過(guò)融化還原而制得的棕褐色人造剛玉。由于剛玉硬度高，提高摩擦系數(shù)的程度高于氧化鋁，極小用量**足以產(chǎn)生良好的增摩效果。用量增加磨損率急劇增大，所以一般用量很少超過(guò)1.5%，且目度**低大于320目**細(xì)度在400-800目。

Brownalumina

The nameis also called emery, with alumina, carbon materials, iron three kinds of rawmaterials in the furnace by melting reduction and preparation of brown alundum.Because the corundum high hardness, friction coefficient is higher than theincrease of alumina, the minimum amount is enough to produce goodfriction-increasing effect. With increasing the content of the wear rateincreases rapidly, so the normal dosage of little more than 1.5%, and the goalis the lowest in more than 320 orders, the best fineness in 400-800.