Physical vapor deposition of titanium nitride on a nonconductive substrate

DETAILED DESCRIPTION Briefly, according to this invention, there is provided a process of physical vapor deposition of a refractory coating, preferably a titanium nitride coating on a nonconductive substrate such as a ceramic substrate.
The process involves cleaning the nonconductive substrate surfaces and then depositing by physical vapor deposition a first layer of a refractory metal such as titanium and then depositing a second layer of a refractory metal compound such as titanium nitride to produce a coated nonconductive substrate having enhanced coating adhesion.
The first layer increases the electrical conductivity of the nonconductive substrate such that electrical biasing in the ion-plating process becomes effective.
An ion-plated titanium nitride coating on a ceramic substrate, such as a ceramic insert cutting tool, has been found to reduce flank wear, reduce the coefficient of friction between the cutting tool and a workpiece such as cast iron or nickel-based superalloy in the instance of Si--Al--ON based ceramic substrates or carbon and high temperature steels in the instance of Al.
sub.
2 O.
sub.
3 based ceramic substrates, resulting in reduced frictional forces, and because of the chemical stability of titanium nitride, act as a diffusion barrier between the insert cutting tool and the workpiece thereby reducing tool catering, flank wear and nothing problems.