| 摘要 |
A cermet compsn. comprises >=48 wt.% Al2O3, 5-50 wt.% Ti B2, ZrB2 or HfB2, 0.35 wt.% nitrides and carbides of refractory transition metals (Ti, Zr, Hf, V, Nb, Ta, Cr, Mo or W), 0-6 wt.% alloy metal and 0.3-3 wt.% Mg O. The cermet is used for cutting tools and abrasion resist and parts. MgO improves sintering but excessive amts. produce notches in the cutting tool. The carbides and nitrides gives grain-growth stability. Small amts. of Fe (4 wt.%) reduce the sintering temp. by 50-75 degrees C and the cutting tools have increased fatigue strength and wear resistance. Composite tools can be used. These are made by electrodepositing a thin layer of cermet direct from the sintering process or previously machined, with the aid of Ni, and braging the coating onto a carbide substrate using a Cu-Ni-Ti alloy. |
