Increasing the deposition efficiency (DE) and consequently reducing the manufacturing costs has been always one of the central goals in thermal spraying. Hence, the effect of modifying various spraying parameters on DE has been widely investigated in the literature. However, there has not been a methodology so far to correlate the in-flight particle properties with their DE on the substrate locally. In this study, a method is developed to determine the local deposition efficiency (LDE) of the plasma spraying process based on optical particle diagnostics of the in-flight particles. To this end, the entire free-jet transverse section is divided into several non-overlapping focal planes and the size and velocity of the particles are measured at these focal planes. Furthermore, the in-flight particle temperatures are captured in a measurement grid normal to the gun axis. The experiments are conducted with alumina spray powder and a three-cathode plasma gun. The LDE is calculated based on the spatial distribution of the in-flight particle mass flow rate (PMFR) and the local deposited mass on the substrate. Subsequently, the interdependencies between the in-flight particle properties and the calculated LDE are investigated using a nonlinear regression model.

提高沉积效率（DE）并因此降低制造成本一直是热喷涂的主要目标之一。因此，在文献中已经广泛研究了改变各种喷涂参数对DE的效果。但是，到目前为止，还没有一种方法可以将飞行中的粒子特性与其在基板上的DE进行局部关联。在这项研究中，开发了一种基于飞行中粒子的光学粒子诊断来确定等离子喷涂过程的局部沉积效率（LDE）的方法。为此，将整个自由射流横截面分成几个不重叠的焦平面，并在这些焦平面上测量颗粒的大小和速度。此外，飞行中的粒子温度被捕获在垂直于喷枪轴的测量网格中。用氧化铝喷雾粉和三阴极等离子枪进行实验。LDE是根据飞行中粒子质量流量（PMFR）的空间分布和基材上的局部沉积质量计算的。随后，使用非线性回归模型研究飞行中粒子特性与计算得出的LDE之间的相互依赖性。