Research On The Law Of Cubic Press Heating Process By Finite Element Method

Cubic press is the most widely used apparatus for synthetic diamond products in our country which have been the basis of national diamond synthesis industry. As the cavity under high pressure and high temperature, the temperature inside it is difficult to measure directly and the heating process is influenced by many factors, literatures on the law of heating process and the influence factors are rare. The understanding of the laws in cubic press heating process restrict the improvement of accuracy in temperature control, lead to the design and realization of synthetic process for high quality diamond products lacking effective guidance.The thesis mainly studies the heating law of cubic press and temperature distribution in the synthetic cavity, aimed to illuminate or quantify the effects of those influence factors to heating process in diamond synthesizing, get the characteristics of temperature distribution in typical assembly style, achieve the control of temperature trajectory in cavity. A thermal-electric coupled numerical model was made by ANSYS, some studies on different heating manners and assembly style had been carried on by the model.The results show that there is an relative fixed law of time to rise temperature, heating power has no effect on that, but the thermal conductivity of pressure transmitting medium, initial temperature of the press, heat sinking and cooling conditions, the specification of current ring are all have effect on the law. Different factors'affection act at different time zone and have different influence. Direct heating and indirect heating and hybrid heating have different law of time to rise temperature, which due to the heat dissipation is easy or not. When the press is heating with constant power, the temperature will arrive at an equilibrium temperature after enough time which has a linear relationship between the power and the initial temperature. Combine the law of time to rise temperature and the linear relationship between equilibrium temperature and heating power can achieve controlling of the temperature trajectory. The current state from current ring to synthesis rod is a bit like what from an electrode to ground, so diasporas resistance must be considered. The characteristic of temperature distribution in direct heating and indirect heating is different, hybrid heating method has better scalability.