Coatings continued hard-film

In practice there is a continuous range of coating hardnesses varying from very soft to very hard, and the hardness is determined not only by the binder but by the concentrations of molybdenum disulphide and other solid components. The definition of hardness is also relative to the service contact loads. A coating of intermediate hardness may behave like a hard film under low contact pressures or like a soft film under high contact pressures. As a result, it is very difficult to compare the quoted load-carrying capacity and wear lives of different films tested under different conditions by different research groups. 

Plastic parts with a thin black layer on one side can be continuously welded in place. For example, if the black layer is one part of a bUayer, coextruded sheet, it could be unroUed and welded in place. The heat needed for welding would be generated precisely where it is needed, minimizing damage to the part and allowing the joining of thin polymer films. Thin films, particularly when coated on a metal, that are hard to join by other methods should he readily and rapidly joined by infrared welding. 

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