摘要：

The structure and properties of coatings obtained by thermal or cold gas spraying depend strongly upon different parameters among which the quality of the powder, wire, rod or cord used plays a key role. Powder quality can affect coating performance through different effects. First are presented the different powder manufacturing techniques: atomization, fusing and crushing, milling and sintering, ball-, attrition-, cryo-milling, mechanical alloying and milling, spray-drying, spheroidization, cladding, sol-gel and solutions, self-propagating high-temperature synthesis, cermets. The influence of powder morphologies on coating properties is discussed through examples. Then are presented powder classification methods and characterization: sampling, XRD, elements distribution, composition and purity, particle shape, size distribution, flow ability and surface area. The different types of powder feeders and the hazards related to particles are finally presented. Wires, cored wires, rods and cords are also presented and the chapter finishes with problems linked to polymer powders according to their physical, chemical and mechanical properties widely different from those of metals, alloys ceramics and cermets

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