Thermal spray coatings can be effectively used to provide protection of materials from wear, erosion, corrosion etc. The components used under a high temperature condition, for example boiler tube in the boiler, are generally subjected to the severe corrosion by sulfur and vanadium. Because of variations of burning fuels and combusting conditions, the corrosion conditions may change greatly especially in the case of garbage-fired boiler[1]. For such high temperature corrosion, Ni-Cr alloy which contains chromium over 20% presents excellent corrosion resistance[l]. Therefore, Ni-Cr coating produced by thermal spray processes has been widely effectively used as the protective coating[2,3]. On the other hand, the Ni-Cr coatings must have satisfactory mechanical properties to ensure the sufficient adhesion along with wear and erosion resistances In order to utilize effectively the potential of coating, the coating should be optimized simultaneously for mechanical performance and anti-corrosion performance. However, although there are many literatures concerning with the applications of Ni-Cr coatings, only few discuss systematically the effect of spray conditions on the coating properties. The aim of present paper is to clarify systematically the influence of plasma spray conditions on the mechanical properties using the orthogonal regression experiment design method in order to optimize the coating by the mechanical properties of the coating such as adhesive strength, abrasive wear, erosion and hardness.
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