The analysis of the effect of the pressurization block on diamond synthesis cavity by finite element method

The cubic press is a common high-pressure equipment, used in scientific research and industrial production of diamonds because of its large sample cavity, simple operation, low cost, and high production efficiency. However, the ultimate pressure of the cubic press is low, which can be increased by adding the pressurization block (PB) to the assembly. In this paper, the pressurization effect of differently-shaped PBs (circle pressurization block (CIPB), square pressurization block (SPB), square frustum pressurization block (SFPB), and concave pressurization block (COPB)) was compared by the finite element method (FEM) calculations. Although the bottom areas of these PBs were identical, the pressurization effect of COPBs was better than that of other PBs. The main reason was that the shape of the COPB better contained pyrophyllite and reduced its outward flow. FEM calculations were also used to investigate changes in the temperature and convection fields inside the assemblies using COPBs. The results showed that adding COPBs increased the temperature difference between the top and bottom of the catalyst, increased the catalyst's convection velocity, and ultimately accelerated the diamond growth rate. •The pressurization effects of different shape pressurization blocks are compared, and the reasons for the different pressurization effects of pressurization blocks are analyzed•The change of temperature field and convection field in catalyst after using pressurization block is compared. It is found that the growth of crystal can be accelerated by using pressurization block assembly.