Investigation on flattening behavior of thermal sprayed particle based on systematic data on 3-dimensional transition map

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In a first year, the effect of substrate heating on the transition phenomenon in the flattening behavior of thermal sprayed particle was systematically observed. To perform this, change in the substrate surface property, especially roughness property, due to the oxidation was precisely analyzed in nano meter range. Based oh the analyzed result, effect of wetting at particle/substrate interface on the flattening of thermal sprayed particle was investigated. In more detail, the substrate surface once heated in an air atmosphere was analyzed both by a chemical way and a physical way, that is, the chemical composition and oxide layer thickness change by Auger analysis and roughness change in nano meter range by atomic force microscope was investigated. The flattening behavior on the substrate once heated in an air atmosphere was observed precisely as well. From the relation between analyses results on the substrate surface change due to oxidation and transition change in the flattening beh … More avior of the particle on the substrate surface was discussed. In a second year, the effect of ambient pressure on the transition behavior of thermal sprayed particle was systematically investigated on several kinds of sprayed metal materials. The relation between critical transition pressure in ambient pressure and the particle material thermally sprayed was investigated.From the results obtained, followings were revealed in the present research : 1)chemical change on the substrate surface due to the oxidation was quite few, 2)physical change, especially roughness change in nano meter range, was typically recognized due to the oxidation, 3)the wetting condition at particle/substrate interface was effectively affected by the roughness change in nano meter range, 4)change in the wetting condition due to roughness change might dominate the transition behavior of thermal sprayed particle, 5)the transition phenomenon was recognized as well by just reducing the ambient pressure. The transition behavior due to the change both in the substrate temperature and ambient pressure was summarized in a 3-D transition map. Thermal spraying process can be controlled more effectively by using of this 3-D transition map. Namely, the desired coating microstructure and property are given by just selecting an appropriate combination of substrate temperature and ambient pressure conditions. The result implies that a certain equivalency may exist between the change in the temperature field of the substrate surface and the change in the ambient pressure on the substrate surface. Consequently, it was implied from the results obtained in the present research that the dynamic wetting could be the possible domination on the flattening of thermal sprayed particles. Less