Experimental on Sintering Diamond with Direct Bonding between Diamond Particles

Diamond powder was placed on the pure Ni or alloy Ni70Mn25Co5 substrate and held at high pressure of 6.3 GPa and high temperature of 1 440 to 1 650 ℃ for 3 to 40 minutes. Composition and microstructure of the sintering diamond were studied by the scanning electron microscopy, X-ray diffraction and Raman spectroscopy. It was observed clearly that the continuous phase between diamond particles was produced extensively in the region where metal was filtrated sufficient. No carbide or graphite was detected in that region and other places. Homogeneous and compact microstructure with the continuous phase between diamond particles was observed in all the sample with the size of 7 mm2 mm, which was sintered using diamond powder with the grain size of 7 to 14 m and the Ni70Mn25Co5 alloy as a substrate.