Properties of sputtered hard coatings depending on macro- and micro-geometry of the substrates

The deposition of hard coatings on tools and machine components is a well-known technique to produce wear resistant surfaces in many cases. In many cases, lots of small tools and machine parts are deposited in large deposition units in one batch by the use of substrate manipulation. In addition, components with large surfaces need special manipulation. This investigation points out how the choice of substrate influences the coating properties in a given deposition process. Aspects of material, geometry and kinematics are studied in addition to the known levels of influence, such as deposition technology, equipment and deposition parameters. Not only macro-geometry, but also micro-geometry determine the quality of a coating. Specimens of different size, shape and roughness were coated and analysed to provide a contribution towards a better understanding that the same deposition processes may produce coatings with different properties depending on the objects to be coated. As a result, a general model for substrate influences on coating properties is proposed. This model takes into account the important substrate aspects for deposition of thin films on mechanical components in tribology with vacuum technologies. This information is necessary when changing the nature or number of objects to be coated in a given deposition unit, especially for different machine parts instead of small tools. (C) 1997 Elsevier Science S.A.