Effect of Solidification and Wetting on Flattening Behavior of Thermal Sprayd Particles.

在本研究中，研究了热喷涂颗粒在溅射层中的固化和在溅射层/基体界面处的润湿对热喷涂颗粒扁平化的影响。在第一年中，我们进行了以下的研究：（1）基板的热传导率和动态润湿对平坦化的影响;（2）模型实验的尝试。在保持界面润湿条件不变的条件下，研究了颗粒在每个Au涂层衬底上的平坦化行为的变化，结果证实了衬底的热导率越大，转变温度越高的趋势。这意味着初始凝固对飞溅起着重要作用。在保持初始凝固条件不变的条件下，研究了不同金属PVD膜在AISI 304基体上的粒子扁平化行为，结果表明，膜层金属活性越高，相变温度越高。这是 ...更多信息 在第二年，我们进行了一个更加精确的模型试验，观察了水滴的扁平化行为，二是进行了一个现场试验，观察了喷雾颗粒的扁平化。由于粒子到达衬底的触发器的设置相当困难，因此对溅射后表面的固化和平坦化的原位观察被推迟到未来的研究。从本研究中得到的实验和每一个理论公式之间的压扁率的比较，显着的差异，这些之间的认可，即使在最先进的兰格尔的分析。在分析中需要更多的改进。通过对液滴扁平化行为的原位观察，证实了飞溅型飞溅以相当高的加速度扩展，飞溅的特征在于后表面具有相当多孔的结构。结果表明，飞溅是由低粘性流体从碰撞中心向外围喷射而形成的。在转变温度附近的飞溅图案的急剧变化的原因，在未来的研究中进行了更详细的调查。少

In this research, the effects of both solidification in the splat and wetting at splat/substrate interface on the flattening of the thermal sprayd particle were investigated. In the first year, 1) investigation of the effects of both thermal conductivity of the substrate and dynamic wetting on the flattening, 2) trial of the model experiment, were carried out. Keeping the wetting condition at interface constant, change in flattening behavior of particle on each Au coated substrate was studied, as a result a tendency was confirmed that the larger thermal conductivity of the substrate was the higher the transition temperature was. This means that the initial solidification plays a significant role to the splashing. Keeping the initial solidification condition constant, flattening behavior of the particle on AISI304 substrate with various metal PVD films was studied, as a result it was confirmed that the more active the film metal was the higher the transition temperature was. This sugges … More ts a tendency difficult to splash for excellent wetting condition.In the second year, 1) more precise observation of the flattening behavior of droplet in model experiment, 2) trial of in situ observation of flattening of the sprayd particle, was conducted. As the setting of the trigger for the particle's arrival on the substrate was considerably difficult, in situ observation of the solidification and flattening in the rear surface of the splat was postponed to the future study. From the comparison in the flattening ratio between experimentally obtained in this study and each theoretical formulae, remarkable discrepancy between these was recognized even in the most advanced Rangel's analysis. More improvement is needed in the analyzes. It was confirmed that the splash-type splat spread with quite high acceleration from the in situ observation of the flattening behavior of the droplet, and the splash splat was characterized as the quite porous structure in the rear surface. It was clarified from these facts that the splashing was formed by jetting away of the low viscous fluid flow from collision center to periphery. The reason for the drastic change in the splat pattern near the transition temperature has to be investigated in more detail in the future study. Less