Surface modification of dense silicon nitride by ion beam techniques

The use of dense Silicon Nitride under wear and at high temperatures is restricted by various damaging processes, like creep, oxidation and subcritical crack growth. Most of these processes are determined by surface effects. That's why the present paper shows, that by using ion beam methods the ceramic surfaces can be modificated, by coatings or coating systems with properties that can be adapted to the special applications of the materials. The advantages of this methods are the slight temperature exposition of the specimens, the high adherision, density, pureness, and figure stability. They allow to produce desirable compositions with gradients of concentration and properties. One example for this are Pt-coatings on dense silicon nitride (SSN, HPSN), which lead to improved oxidation resistance for short and long time exposition in air up to 1400 degree. Si3N4- and SiC- coatings on this materials lead to better oxidation and mechanical high temperature properties.