Hard Tool Materials : General term for tool materials like cemented carbide alloy, cermet, ceramics, sintered CBN, sintered diamond, high speed steel and alloy steel, etc. Appearance : Varies depending on the type of material. Eg. grey, black, gold, etc. Smell : None.CONSTITUENTS:Carbide, nitride, carbon nitride, oxide, such as W, Ti, Al, Si, Ta, B, V and metals such as Fe, Co, Ni, Cr, Mo.Surface conditions affect toughness of cutting tools. Therefore, use a diamond grinding wheel for finishing. Hard tool materials are extremely hard and brittle at the same time. Thus, they may be broken by shocks and tightening with excess force.