In:
Journal of Vacuum Science and Technology, American Vacuum Society, Vol. 12, No. 4 ( 1975-07-01), p. 743-748
Abstract:
Cemented carbide parts coated with several-micron-thick layers of hard material are now used in large quantities in machining, particularly for turning and milling. Applications for jewelry purposes are assuming increasing importance. Following a brief survey of wear mechanisms in machining, the wear behavior of homogeneous coatings of TiC, TiN, and Al2O3 is discussed. Some conclusions concerning the wear-reducing effect of these coatings are derived. It is found that a complex interrelationship of several factors, such as diffusion barriers, reduction of friction, thermal conductivity, and others, play an important part. Effects of hardness and chemical behavior of hard-material coatings, especially of TiC and TiN layers on the wear decrease, are mentioned. The wear behavior of composite coatings consisting of TiC and Ti-carbonitrides of varying composition is then considered. By incorporation of these hard materials into multiple, inhomogeneous layers, significant improvements over homogeneous single-layer coatings are achieved. In addition to great hardness, the application of hard material layers for jewelry demands corrosion resistance, an attractive color, and good polishing characteristics. Examples for the corrosion resistance of TiC and TiN and the colors of Ti-carbonitrides are presented. The polishing characteristics of hard-material layers greatly depend on surface roughness. It is shown how roughness and surface structure of TiN layers produced by the CVD method vary in dependence of the deposition temperature but at equal deposition rate. Some important requirements for coatings applied to tools and jewelry articles and possible methods for their production are mentioned.
Type of Medium:
Online Resource
ISSN:
0022-5355
Language:
English
Publisher:
American Vacuum Society
Publication Date:
1975
