Calorimetric Study on the Sintering of Copper Powder Compact

The change in specific heat of copper powder compact during sintering at a constant heating rate was measured by means of Nagasaki-Takagi\u27s calorimetric procedure. It was found that the sintering process was accompanied by the release of energy in the lower temperature range between 230°and 520℃ and by the absorption of energy at temperatures above 650℃. The total amount of thermal energy released in the lower temperature range was 2.46 calories per gram, which corresponds to the annihilation of vacancies of 7・10^ per atom. It was also found that the rate of this energy release obeyed an exponential law, and that the activation energy for this process was about 13.1 kcal. per mol. From these facts it was concluded that the predominant mechanism of material transfer in the sintering process in this temperature range would be a surface diffusion or a like mechanism associated with vacancy migration. It was not clarified whether the heat-absorbing reaction at temperatures above 650℃, essentially related to the sintering mechanism at high temperatures