In the thermal spray process, feedstock materials are heated to above those melting points. Therefore the deterioration of the characteristics such as oxidation, thermal alteration and phase transformation of the feedstock materials becomes a problem. The solid particle deposition processes such as cold spray and aerosol deposition are expected as a way of preventing this problem. Cold spray uses mainly a soft metal powder as the feedstock powder material and the powder material deposits in an atmospheric condition. On the other hand, aerosol deposition uses mainly a ceramic fine powder as the feedstock powder material and the powder material deposits in a vacuum condition. Both processes are based on a collision of solid particle. Therefore it seems that there is a common deposition mechanism. In this study, the deposition mechanism of solid particle was investigated by microscopic observation and elemental analysis. A simple mixture of aluminum and copper was used as feedstock material in cold spray and aerosol deposition. The observation confirmed a metallic bonding at particle interface in both deposition processes. However, the metallic bonding is not a main at interface in aerosol deposition compare with the cold spray process. The bonding through the oxide layer has been suggested.

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In this paper, the possibility of using electrochemical galvanic coupling current noise analysis was making the corrosion behavior in 3.5mass% sodium chloride solution of thermal sprayed Al-Mg alloy coatings on carbon steel substrate obtained by gas flame spray method. In case of the bulk Al-Mg alloy, galvanic coupling current measured using two bulk specimens was almost the same as the corrosion rate calculated by weight loss. According to the results from galvanic coupling current analysis, the corrosion rates of thermal sprayed Al-Mg alloy coatings increase in the following order: Al<Al-2.5Mg<Al-5.0Mg.

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