Design and Development of a Centrifugal Atomizer for Producing Zinc Metal Powder

Abstract

In the present work a preliminary design of a centrifugal atomizer for producing zinc metal powder was studied. In the design process, the consumed power and the atomizing disc size were first estimated. The trajectory of flying melt droplet from the edge of atomizer disc and the temperature profile were predicted using a concept of heat transfer in an external flow for calculating the size of atomizer chamber. A simple laboratory-scale atomizer was built. The performance of the atomizer was studied by using pure zinc metal as a model material. The effects of rotating disc speed on median particle size, particle size distribution and standard deviation, production yield, and morphology of the atomized zinc powder were investigated. The atomization was carried out using graphite flat disc, melt pouring temperature, preheating disc temperature and melt feed rate of 40 mm, 550 °C, 300 °C and 50 kg/h, respectively. The atomizer disc speeds were varied from 10,000 to 30,000 rpm. It was evidenced from the experimental results that the median particle size and standard deviation of zinc metal powder decreased with increasing disc speed. The production yield tended to increase with increasing rotating speed. SEM images revealed that most zinc metal particles were irregular, elongated flakes. The produced zinc power in this study may be suitable for use as a friction material for manufacturing brake pad in the automotive part industry.