Suspension plasma spray (SPS) is going through a transition phase from research and development to daily use on production lines. Improving repeatability and reproducibility of coating elements and parameters makes SPS a replacement of former well-developed processes. This transition can be achieved by using in-flight particles diagnostic systems to monitor and control key parameters that influence the coating microstructure. Temperature and velocity of the in-flight particles are among the most critical parameters that should be monitored. However, accurately characterizing the in-flight particles in SPS is particularly challenging due to the small particle size of coating materials, harsh spray conditions, considerably shorter spray distances compared to APS, possible interference from the solvent, and limitations of previous measurement systems. In this study, different strategies were investigated to improve the accuracy of temperature measurements of in-flight particles in SPS. For this purpose, two light collection configurations (double-point and single-point measurement) were investigated along with the influence of plasma radiation. The results were evaluated by collecting and studying splats. The size and shape of splats were correlated with the temperature of in-flight particles in order to confirm the accuracy of the sensor’s temperature measurements. In addition, the sensitivity of temperature measurements to the optical filter used for two-color pyrometry, reflection of plasma radiation from surrounding objects, and direct radiation from plasma were investigated. The results showed that the single-point measurement configuration was well adapted for SPS.

中文翻译：

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用于监测悬浮等离子喷雾中飞行颗粒温度的在线诊断系统

悬浮等离子喷涂 (SPS) 正在经历从研发到生产线日常使用的过渡阶段。提高涂层元素和参数的可重复性和再现性，使 SPS 取代了以前完善的工艺。这种转变可以通过使用飞行中的颗粒诊断系统来监测和控制影响涂层微观结构的关键参数来实现。飞行中粒子的温度和速度是应该监测的最关键参数之一。然而，由于涂层材料的小粒径、苛刻的喷涂条件、与 APS 相比明显更短的喷涂距离、溶剂可能的干扰以及先前测量系统的局限性，在 SPS 中准确表征飞行中的颗粒特别具有挑战性。在这项研究中，研究了不同的策略来提高 SPS 中飞行粒子温度测量的准确性。为此，研究了两种光收集配置（双点和单点测量）以及等离子体辐射的影响。通过收集和研究splats来评估结果。飞溅的大小和形状与飞行中颗粒的温度相关，以确认传感器温度测量的准确性。此外，还研究了温度测量对用于双色高温计的滤光片、来自周围物体的等离子体辐射的反射以及来自等离子体的直接辐射的敏感性。结果表明，单点测量配置非常适合 SPS。研究了不同的策略以提高 SPS 中飞行粒子温度测量的准确性。为此，研究了两种光收集配置（双点和单点测量）以及等离子体辐射的影响。通过收集和研究splats来评估结果。飞溅的大小和形状与飞行中颗粒的温度相关，以确认传感器温度测量的准确性。此外，还研究了温度测量对用于双色高温计的滤光片、来自周围物体的等离子体辐射的反射以及来自等离子体的直接辐射的敏感性。结果表明，单点测量配置非常适合 SPS。研究了不同的策略以提高 SPS 中飞行粒子温度测量的准确性。为此，研究了两种光收集配置（双点和单点测量）以及等离子体辐射的影响。通过收集和研究splats来评估结果。飞溅的大小和形状与飞行中颗粒的温度相关，以确认传感器温度测量的准确性。此外，还研究了温度测量对用于双色高温计的滤光片、来自周围物体的等离子体辐射的反射以及来自等离子体的直接辐射的敏感性。结果表明，单点测量配置非常适合 SPS。