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

第一年，系统地观察了衬底加热对热喷涂颗粒扁平化转变现象的影响。为此，在纳米范围内精确分析了基片表面性质，特别是表面粗糙度因氧化而发生的变化。在此基础上，研究了颗粒/基材界面润湿对热喷涂颗粒扁平化的影响。更详细地，用化学方法和物理方法分析了在空气气氛中加热的衬底表面，即用俄歇分析研究了衬底表面的化学成分和氧化层厚度的变化，用原子力显微镜研究了衬底表面在纳米范围内的粗糙度变化。还精确地观察到了在空气气氛中加热后衬底上的展平行为。从BEH…中氧化引起的基片表面变化与过渡变化的分析结果之间的关系进一步讨论了颗粒在基片表面的行为。第二年，系统地研究了环境压力对几种喷涂金属材料上热喷涂颗粒转变行为的影响。研究结果表明：1)氧化引起的颗粒表面化学变化很少，2)氧化引起的物理变化，特别是纳米范围内的粗糙度变化是典型的物理变化；3)纳米范围内粗糙度的变化有效地影响了颗粒/基材界面的润湿状态；4)粗糙度变化导致的润湿状态的变化可能主导着热喷涂颗粒的转变行为；5)降低环境压力也可以识别出这种转变现象。在三维转变图中总结了由于衬底温度和环境压力的变化而引起的转变行为。利用该三维过渡图可以更有效地控制热喷涂过程。也就是说，只需选择适当的基片温度和环境压力条件，就可以给出所需的涂层组织和性能。结果表明，衬底表面温度场的变化与衬底表面环境压力的变化具有一定的等价性。因此，本研究的结果表明，动态润湿可能是控制热喷涂颗粒扁平化的主要因素。较少

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