Role of valence electron of vanadium carbide in metallization of diamond surface

摘要

We have developed a modification process for diamond using VHx, Ag-Cu eutectic powder and silver paste mixture for joining diamond easily to a metal jig for polishing precision. The average joint strength of the modified diamond, brazed to 42 Invar plate using Ag-Cu eutectic filler without reactive metal, was 118 MPa. Electron Prove micro Analyzer (EPMA) analyses revealed the deposition of silver on the reaction products. This successful deposition was due to small misfit value of silver on VC (0.0177) despite of the large value for diamond (0.146). Using lattice constants determined from the X-ray diffraction patterns, Mulliken's population analyses through a scat program were performed for the various carbide formations and used to explain the role of the valence electrons supplied from vanadium carbides. As determined from DV-Xα analysis, the initial formation of V_2C induced the adhesion of metal vanadium on the diamond surface by weak binding forces. The change of the electric structure in the V_4C_3 formation provided the metallic property in the limited direction of [111] on the modified diamond surface by vanadium, and which it generated by wetting of Ag-Cu melt. This V4C3 formation was necessary for the metal melt to adhere onto the modified diamond surface.