Diamond synthesis through the generation of plasma during spark plasma sintering

Abstract

Spark plasma sintering (SPS) of carbon nanotubes based materials to diamond was conducted at a very low pressure in vacuum and argon atmospheres. The phases and microstructures of the sintered samples were analyzed by Synchrotron X‐ray, Raman spectroscopy, and scanning electron microscopy. Diamond phases are created from carbon nanotubes/FeNi mixtures at pressure of 9.55 MPa in vacuum and argon atmospheres during SPS. At this pressure, carbon flowers, and perfect diamond crystals are obtained at 1200 °C only in the argon atmosphere. The consequences provide an indirect evidence for the existence of plasma during SPS. The argon atmosphere promotes the plasma generation and thus enhances the diamond transition. Diamonds are obtained from carbon nanotubes/FeNi at 1200 °C and 9.55 MPa in argon atmosphere of SPS.

Field‐Assisted Sintering Technology/Spark Plasma Sintering: Mechanisms, Materials, and Technology Developments

“…The formation of diamond from fullerene C60 without any catalysts was also possible in FAST/SPS run under moderate pressure of 50-80 MPa at 1150-1300°C with a heating rate of 100°C min À1 in vacuum, i.e., much "milder" conditions than usually required for diamond production. [224,225] Polycrystalline diamond crystals with sizes up to 250 mm and transition rates about 30% were observed. The transformation into diamond takes place by direct reconstruction of sp 3 carbon, which exists as a high fraction in the fullerene.…”

“…[1][2][3][4] This method can indeed be used to synthesize new compounds [5,6] and/or to densify materials in one step.…”

Manipulation of matter by electric and magnetic fields: Toward novel synthesis and processing routes of inorganic materials

“…Two or multiple phases react at their interface to form new solid metastable phases. Convincing first results have been shown for the formation of layered MAX phases (Ti-Si-C) [39] or diamonds from fullerene and carbon nanotubes [40]. Intermetallic clathrates Na 24 Si 136 , which have interesting thermoelectric properties but whose preparation is exceedingly challenging, were successfully produced under electric field [41].…”

A Review of Binderless Polycrystalline Diamonds: Focus on the High-Pressure–High-Temperature Sintering Process

“…With the development and democratization of the Spark Plasma Sintering (SPS) technique at the beginning of 21st century, few studies from one lab have synthesized/sintered diamond at relatively low-pressure–high temperature [ 78 , 79 , 80 , 81 , 82 , 83 , 84 , 85 ].…”