Investigation of dynamic wetting behavior in flattening of thermal sprayed particles and dominating relation between wetting and initial solidification

固体化和界面湿润对热喷雾粒子的平坦行为的影响是在与粒子相关的因素保持恒定的条件下的关键要素。在润湿和初始固化之间的主导关系，不管怎样，还没有完全理解。由于热喷雾粒子的平坦行为可以被认为是动态湿润现象，以及热喷雾粒子和主导关系之间的平坦湿润行为，在调查中，在调查的第一年，粒子在金属平板基底表面覆盖的各种温度下，动态湿润行为。以及粒子/基底界面对粒子的平坦行为的影响。粒子的过渡温度和热行为之间的关系既具有强线性，又具有更差的线性。 ... More 界面是静态的湿性，而管家是线条的梯度。这一指标甚至在陶瓷颗粒中，当碎片封闭的底部温度接近过渡温度时，快速固体在碎片封闭的底部部分。However，就像飞溅被观察到在贫湿的物质组合中一样，它被证明是平坦湿湿的最大主导因素。“熔化金属水滴的自由落体实验也是以热喷雾的一种模拟方式进行的。根据结果，据估计，在水滴底部表面上独特的多孔微结构是由在气体物理上捕获形成的。在第二年，动态湿润对热扩散颗粒的平坦行为和初始确定之间的主导关系的影响。在splash splat中，中心磁盘的部分被扩展到了底层温度的增加，而且当湿得很糟糕的时候，完全分散的splat可能经常被观察到。从这些结果中可以看出，它可能被合并，因为似乎湿了，将成为底层热喷雾颗粒中最大的主导因素。“在碎片底部部分的快速初始固体是一种想法，因为当颗粒湿到达某些关键条件时，如果颗粒的速度和温度也会受到碎片的影响，如果颗粒的速度和温度也会受到碎片的影响和过渡温度。”由于粒子的速度、温度和直径增加，过渡温度增加了。Splashing parameter ： K=WeイD10.5イD10.25イD1 is usually used as a determinant of the splashing。过渡温度增加了，因为根据粒子中的可测量数据的飞溅参数增加了。However，根据与过渡温度的关系，我们发现只有Splashing参数无法确定过渡现象。Then， Flattening K value ： Kf= 0.5 aイイD11.25イD1-0.3イD1K was defined and introduced in this study。它被包括，当Splashing似乎要移动到Splat的Kf值达到某些关键值时，来自于在低压力下自由的Fallen实验，它被揭示为大气层本身在水滴/基底界面上有一种抑制性的作用。从裸露的基底上的splat之间的比较和在金涂层基底上发现了这样的比较，即在splat/基底界面上的润湿得到了改进，从而通过将基底表面与基底温度的增加相结合的形态变化。从高速视频的观测结果中，发现了一个飞溅碎片的闪烁速度远远高于磁盘碎片的速度。The Higher flowing of the splat Seems to be caused by the ultra rapid cooling at the bottom part of the splat。Less（低）

Effects of both solidification and interface wetting on the flattering behavior of thermal sprayed particles are quite essential under the conditions of the particles relating factors kept constant. Dominating relation between wetting and initial solidification, however, has not been fully understood yet. As the flattering behavior of the thermal sprayed particles can be considered to be dynamic wetting phenomenon, dynamic wetting behavior in flattening of the thermal sprayed particles and dominating relation between wetting and initial solidification were investigated in this research.In the first year, several kinds of particles were plasma sprayed on the metallic flat substrate surface held at various temperatures, and the effects of both solidification and wetting at particles/substrate interface on the flattening behavior of the particles were investigated. The relation between transition temperature and thermal conductivity of the particles had the strong linearity, and the worse … More was the static wettability at interface, the steeper was the gradient of the line. This indicates that even in the ceramic particle, the rapid solidification at the bottom part of the splat occur when the substrate temperature is close to the transition temperature. However, as the splashing was observed in the material combinations of poor wetting, it was indicated that the most dominating factor on the flattening was wetting. Free falling experiments of the molten metal droplets was also conducted as a simulation of the thermal spraying. From the results, it was estimated that the unique porous microstructure on the bottom surface of the droplet was formed by the taking in a gas physically.In the second year, effect of dynamic wetting on the flattening behavior of the thermal sprayed particles and the dominating relation between wetting and initial solidification were investigated. The central disk part in the splash splat expanded gradually according to the increasing of the substrate temperature, and wholly scattered splat could be often observed when the wetting was bad. From these results, it may be concluded that the wetting seemed to be the most dominating factor in the flattening of the thermal sprayed particle on the substrate. The rapid initial solidification at the bottom part of the splat was thought to affect on the flattening of the particle when the wetting reached to some critical condition.In-flight measurement if the velocity and temperature of the particle was also conducted and transition temperature of the splat was measured. The transition temperature increased with increasing the velocity, temperature and diameter of the particles. Splashing parameter : K=WeィイD10.5ィエD1ReィイD10.25ィエD1 is usually used as a determinant of the splashing. The transition temperature increased with increasing Splashing parameter based on the measured data of the particle. However, from the relation with the transition temperature, it was found that only splashing parameter could not determine the transition phenomenon. Then, Flattening K value : Kf=0.5aィイD11.25ィエD1ReィイD1-0.3ィエD1K was defined and introduced in this study. It was concluded that The splashing seemed to occur when the Kf value of the splat reached to some critical values.From the free fallen experiment under low pressure, it is revealed that the atmosphere itself has an inhibitive action to the wetting at the droplet/substrate interface. From the comparison between the splat on the naked substrate and that on the gold coated substrate, it was found that the wetting at splat/substrate interface was improved through the morphological change of the substrate surface according to the increasing of the substrate temperature. From the observation results of the high-speed video, it was found that the flattening velocity of the splash splat is extremely higher than that of the disk splat. The Higher flowing of the splat seems to be caused by the ultra rapid cooling at the bottom part of the splat. Less