Fundamental Research On The Preparation Of Carbon Nitride By DC Arc Plasma Jet CVD

Carbon nitride is the first compound which was deduced theoretically and hasn’t been found innature yet. Many studies show that carbon nitride has a variety of phase structures, namely α, β, cubic,quasi-cubic and graphite-like phase, etc. In addition to the graphite-like phase, the bulk modulus ofother phases can be compared with diamond theoretically. Carbon nitride is considered to be a newkind of superhard material, which possesses the properties of high chemical inertness, excellentabrasion resistance, etc, and it has broad application prospects in coated cutting tools.In the paper, the fundamental study of carbon nitride preparation was conducted by DC arc plasmajet CVD. The work completed and the results obtained are as follows:1. Repairment and renovation of LP-30DC arc plasma jet CVD facility were completed to meetthe need of carbon nitride deposition. The works done are as follows: the circuit, loop waterways andvacuum system were repared; three kinds of gases (CF4, N2and H2) mixed with other reaction gaseswere added to the plasma torch body; and the substrate bias system was added.2. Based on the stable arc parameters in the preparation of diamond films, the key influencingfactors of arc stability in carbon nitride preparation were studied in different gases. Orthogonalexperiment was adopted to get the optimized process of arc stability in carbon nitride preparation, andfinally the stable rotating arc with high speed was got.3. Micron and nano diamond films were deposited on Mo substrate under different ratio of CH4/H2by DCPJCVD.With1%~3%concentration of CH4, the micron diamond films as transition layer wereprepared. With10%~15%concentration of CH4, the nano diamond films as transiton layer wereprepared.And miron diamond films were deposited on YG6cemented carbide cutting tools by HFCVD.4. The preparation of carbon nitride was conducted in mixed gases of Ar+N2+CF4+H2onsubstrates of Si wafer, CVD thick diamond film, Mo/micron-diamond film, Mo/nano-diamond film,and YG6Carbide/micron diamond film. The characterization result shows that: In addition to Si wafer,carbon nitride was prepared successfully on other substrates; the main content of the sample wereα-C3N4and β-C3N4; and with the increase of substrate temperature, the grain size of carbon nitride andthe nitrogen content increased gradually.