合成金刚石超高压腔内的压力剃度

 用合成金刚石通用的石墨代替过去使用的氯化银作为测定压力的传压介质材料测得了腔内的压力梯度。石墨在压力腔内压力梯度随压力的升高而增大，在中心压力为5.5 GPa时，纵向压力梯度为21.8 MPa/mm，径向压力梯度为18.8 MPa/mm；而且在较低压力下，两个方向的压力梯度相差甚微，随着压力升高，差别则较为显著。但氯化银在压力腔内的压力梯度却随压力的升高而减小。研究了测压腔内的相对压力梯度，发现相对压力梯度随压力的升高而减小。在中心压力为5.5 GPa时，纵向相对压力梯度为0.003 96 mm^-1，径向相对压力梯度为0.003 48 mm^-1。因此，应根据相对压力梯度来合理地设计合成金刚石反应腔内的温度场。

THE PRESSURE GRADIENT IN THE St''''PERHIGH PRESSURE CHAMBER FOR DIAMOND SYNTHESIS

The pressure gradient has been measured by authors using graphire which is widely applied to diamond synthesis instead of traditional ma terial silver chloride. The pressure gradient in graphite pressure chamber increases with the pressure. The axial pressure gradient is 2l.8MPa/mm and the ra.dial one is 1 8.8MPa/mm when the chamber center is at the pressure of 5.5GPa. It has been also found the pressure gradients in the axial direction and radial direction are almost same at low pressure, but the difference becomes remarkable with the increasing pressure. On the other hand, the pressure gradient in silver chloride chamber decreases with the increasing pressure. Some investigations were carried out on the relative pressuregradient and we found it decreases as the pressure increases When center pres-sure is 5.5 GPa the axial relative pressure gradient is 0.00396 mm and the radial is 0.00348 mm-1 , It is suggested that the temperature field could be reasonably designed by taking account of relative pressure gradient.