A1n coated silicon nitride-based cutting tools

Abstract From the Canadian patent

Cutting tools, cutting tool inserts, and wear parts having improved mechanical and chemical wear resistance under demanding conditions of machining speed tempera-, ture, or wear conditions comprising a monolithic or composite silicon nitride-based substrate having a hard adherent coating layer of a refractory aluminum nitride and optionally an outer adherent coating layer of a refractory material. The preferred outer layer refractory materials are the carbides, nitrides, and carbonitrides of Ti, Zr, Hf, Nb, V, Ta, Cr, Mo, and W, and mixtures and solid solutions thereof, alumina and zirconia.