WC Powder Coating Processes for Hard Materials Applications: Sputtering (pp. 363-378)
Authors: (C.M. Fernandes, A.M.R. Senos, M.T. Vieira, Department of Ceramics and Glass Engineering, CICECO, University of Aveiro, Aveiro, Portugal, and others)
Abstract: Coated powders offer a variety of interesting characteristics, where the essential properties of the powder or the final product can be influenced by a specific thin layer. The coating of the powder particles by a second component may be used for protection of the core material towards a reactive environment, intentional arrangement of electrically conductive or non conductive outer-layers, hydrophilic or hydrophobic behaviour, colour effects, or design of controlled microstructures. A review on the tough-coated hard powder (TCHP) production processes applied to tungsten carbide powders was done in the present chapter. TCHP techniques were developed in cemented carbides having in mind the following goals: (i) efficient consolidation by liquid phase sintering with restricted grain coarsening and more uniform phase distribution and (ii) development of harder, higher wear resistant and tougher composite materials when compared with the current ones. Chemical processes, like chemical vapour deposition, direct reduction and precursor precipitation were reported, together with physical methods, such as mechanical synthesis and sputtering. The information available about the coated powders and characteristics of the respective composites were also presented.