Calibration of pressure to 35 GPa for the cubic press using the diamond-cemented carbide compound anvil

Abstract

In the present study, we analyse the mechanical structure for the two-stage anvil cell, and design the two-stage high pressure cell using diamond-cemented carbide compound as anvil-material. The diamond-cemented carbide compound material is synthesized using the 6×2500 ton cubic press in our laboratory. We sinter diamond/Co layer (Φ30 mm×10 mm) on a WC-cobalt substrate (Φ30 mm×13 mm) at high pressures and temperatures, then, we obtain the cubic anvils from the sintered cylindrical chunks by wire-electrode cutting. The diamond-cemented carbide compound anvil has three advantages over the traditional sintered diamond anvil: first, a scaled-up version of the sintered diamond anvil could be obtained by sintering the diamond/Co layer on a WC-cobalt substrate; second, the diamond-cemented carbide compound anvil is machined easily compared with the sintered diamond anvil; and third, the experimental cost using the diamond-cemented carbide compound anvils is much lower than using the sintered diamond anvil. Using the diamond-cemented carbide compound anvil, we design the two-stage 5.5/1.5 (octahedral edge-length/anvil truncation edge-length, in millimetre) assemble. Pressure calibration at room temperature is performed for the 5.5/1.5 assemble using the phase transitions of Zr (α-ω, 7.96 GPa; ω-β, 34.5 GPa) under high pressures. The pressure range of the two-stage apparatus besed on hinge-type cubic press is extended from 20 GPa to about 35 GPa using the 5.5/1.5 assemble. The pressure calibration for the two-stage apparatus using diamond-cemented carbide compound anvil is ongoing in our laboratory. We believe that the pressures above 50 GPa could be achieved using these anvils.