Measurement of the Average Two-Dimensional Surface Temperature Distribution of Drops in a Melt Atomization Process

Abstract

During the production of metal and alloy powders by melt atomization, the knowledge of the surface temperature distribution of drops is essential. This paper shows the application of low-cost industrial CCD-cameras in connection with advanced image processing techniques to measure the average two-dimensional surface temperature distribution of drops in a melt atomization process. These measurements are necessary for comparison with the results of numerical investigations. The two-color pyrometer consists of two standard industrial CCD-cameras with appropriate optical filters. After calibration using a high-temperature furnace, the relative measurement error was smaller than 1.6% within the temperature range of 1273-1873 K. The pyrometer was applied to measure the average temperature distribution during the metal spraying process in a vacuum inert gas atomization facility. The measured temperature distribution averaged over 10 ms shows the development of a hollow cone spray of the atomized metal. The average axial distance between the atomization nozzle and the region of the liquidus temperature was found to be approximately 40 times the diameter of the atomization nozzle.