Coating carbide cutting tools with oxides - by pretreating carbide surface to prevent binder or carbon diffusion into oxide

摘要

In the parent patent, the cemented carbide was coated with a very thin, uniform coating comprising a first layer of =1 carbides and/or nitrides and a second outer layer of =1 wear resistant oxides, esp. alumina or zirconia, deposited from the gaseous phase. In the present patent, the carbide surface is treated to remove free binder (usually Co) and carbon of fix the binder and carbon, e.g. by decarburising to form a eta carbide, and then coated with a ceramic oxide, esp. of Si, B, Ca, Mg, Ti, or Hf.