Microwave-Assisted Molten-Salt Facile Synthesis of Chromium Carbide (Cr₃C₂) Coatings on the Diamond Particles

Abstract

Chromium carbide (Cr3C2) coatings on the diamond were fabricated using the mixtures of molten salt of NaCl and BaCl2, powders of metallic chromium and diamond as raw materials in the temperature range of 750–900 °C by the microwave-assisted molten-salt synthesis. The morphology, microstructure and phase composition of the surface layer were characterized by Scanning Electron Microscopy, Energy-dispersive Spectrometry and X-ray diffraction. The results show that the surface of the diamond particles could be coated with Cr, forming a uniform and continuous Cr3C2-coated layer. The coatings thickness on the diamond can be controlled by adjusting the heating temperature and time. The coating thickness expanded from 0.73 to 2.30 µm when the temperature was increased from 750 °C to 900 °C, and increasing rapidly during the temperature range of 800 °C–850 °C, the coating thickness expanded from 1.30 to 2.80 µm when the holding time was increased from 0.5 h to 4 h. The results illustrate that the microwave-assisted molten salt synthesis plays a positive role in chromium coatings on the diamond, offering a potent method for the surface metallization of diamond.