Study on characteristics of microwave melting of copper powder

Microwave heating has been widely used because of its advantages of higher heating rate, energy efficiency and clean utilization. This paper describes the study carried out on the characteristics of microwave melting of metallic copper powders, and a quantitative description of the heating curve of the copper powders in microwave field is given. The changes in microscopic structure and densification during the process of heating to melting of copper powder with microwave is assessed. The result demonstrated that copper powders could be quickly heated to melting. Heating rate for powdered copper of particle size 25 μm is 25.6 °C/min. Microwave heating efficiency and the heating rate were found to be higher with the decrease in the particle size and increase in microwave power. And also the heating rate had a linear relationship with the reciprocal of the particle size. Microstructure and density indicates that the densification process accelerates when the temperature is above 900 °C, and all the copper particles are heated to melting and shrinkage. At lower temperature the migration of the matter for copper particles is mainly internal diffusion. While the temperature above 1083 °C, among copper particles will be form metallurgical bonding, and the melting process complete quickly.