CVD in Wear-and Corrosion-Resistant Applications

Chemical vapor deposition (CVD) coatings are useful in applications requiring resistance to wear and corrosion over a wide range of temperature. Wear and corrosion protection can be provided by the techniques of hard-facing and plating or by surface modification processes such as boriding, nitriding, carburizing, and ion implantation. The protection these processes provide is adequate in most environments but fail over a period of time if the conditions are too severe. Another useful technique is plasma spraying. It has a drawback of requiring thick deposits to insure adequate protection. It often requires extensive grinding and polishing. Other techniques, such as sputtering, provide excellent protection. CVD suffers limitations to a lesser degree and so it is being used in many industrial applications, particularly those operating in extreme conditions. It is the best solution to severe problems of erosion, friction, or hot corrosion. The number of CVD coating materials for wear and corrosion resistance is relatively small. The most important are—titanium carbide, titanium carbonitride, and chromium carbide.