Maximum Multianvil Cell Assembly Running On Wc Anvils With A Certain Size

Since Tracy Hall invented tetrahedral press in 1958,the multi-anvil static high pressure apparatus(mainly including tetrahedral,cubic and octahedral high pressurepress)has been widely used in the fields of planetary science,high pressure science,materials science and the industrial production of super-hard materials.Today,multi-anvil press can realize a sample volume with centimeters and pressure over 10 GPa.It is a goal to achieve larger samples at higher pressure.However larger size of sample at higher pressure is limited by many external factors,especially in multi-anvil press.Larger sample volume means a bigger size of the secondary anvil.At present,there are few reports of large size multi-anvil press.The loading tonnage,the size of secondary anvil,the edge-length of truncation and the size of the octahedral pressure transfer medium directly determine the volume of the sample.When the loading tonnage and the size of the secondary anvil are fixed,how to obtain the largest sample volume is still a neglected issue.Based on that,this paper offer a method to realize larger cell volume on small size secondary anvil.The main results of this paper is as following:(1)Based on the simplified model of gasket of octahedral press,the maximum volume of flowable area of gasket after loading is calculated,and the maximum volume assembly on secondary anvils with a certain size is determined.According to the calculation results,the possible largest size of the pre-gasket in different assemblies is determined.(2)Larger volume of the samples is achieved by increasing the truncation edge-length on the secondary anvils,optimizing the size of the pre-gaskets and octahedron,and chamfering of octahedron.Based on a 15 MN two-sided type octahedral press in our laboratory,with pyrophyllite as the pressure transfer medium and graphite as the heater,The temperature and pressure calibration experiments were carried out on the assemblies of 14/8,18/11,25/17.(3)By using the 14/8 assembly,of which the temperature and pressure has been calibrated,the diamond produced by CVD method was annealed at high temperature and high pressure,and then irradiated to obtain colors in diamond.Spectra of CVD diamonds treated by different methods were measured,the characteristics of infrared spectrum were compared,and the discoloration mechanism was preliminarily discussed.