Influence Of Carbonization Of Buffer Layer On Structure And Performance Of Carbon-based Hard Film

On the basis of depositing carbon-based hard thin film(including diamond-like film and diamond film, etc.) that high adhesion strength and good quality in combination with architecture design of composite and multilayered films. Three series of high performance carbon-based hard films were deposited, which is including five groups of Ti/diamond composite films, three groups of Cr/DLC multilayer films and four groups of Si C/DLC composite films. We explored the influence of carbonization of buffer layer on structure and performance of hard carbon film. The results obtained were as following:(1) To better understand the influence of the carbonization of Ti interlayer on diamond nucleation and growth, a series of Ti/diamond composite films were deposited on cemented carbide(WC:Co) substrates in a two-step deposition technique. The results allow:(i) Carbonization of different thicknesses of Ti layers affected the grain growth orientation in the Ti C layer. With the thickness increase of Ti layers, the preferential growth orientation of the Ti C layer from being primarily in the Ti C(111) plane to being in three competing planes Ti C(111),Ti C(200) and Ti C(220);(ii) The variation of preferential growth orientation of the Ti C grains affected the grain size and nucleation density of the diamond film;(iii) The tribological property of the composite film are affected by the grain size of diamond. The large grain size of diamond tended to increase the surface roughness of the diamond film and increase the friction coefficient of the composite film.(2) Three groups of Cr/DLC multilayer films all have the smooth surface and the clear structure between the film layers. The interface carbonization has a little influence on film layer structure; With the increase of interface number of Cr/DLC multilayer film, more Cr3C2 phase could be generated, which result in the content of sp2-C increased and the content of sp3-C decreased. And then lead to the change of the hardness of multilayer films; When the modulation period of multilayer film is 400 nm, the Cr/DLC multilayer film has a largest hardness is 18 GPa and a largest elastic modulus is 175 GPa; Three groups of multilayer films all have large fracture toughness. When the modulation period of multilayer films is 200 nm, the film have the largest fracture toughness is 3.75 MPa×m1/2.(3) Four groups of Si C/DLC composite films were deposited on cemented carbide substrate by medium frequency magnetron sputtering to research the influence of C2H2 flow for depositing Si C interlayer on the mechanical property of Si C/DLC composite films. The results shows that:(i) with the increase of the C2H2 flow for depositing Si C interlayer, the content of sp2-C is increased in Si C/DLC composite film;(ii) When the C2H2 flow for depositing Si C interlayer is 70 Sccm, the composite film has the largest hardness is 15.3 GPa and the largest elastic modulus is 142 GPa;(iii) With the increase of C2H2 flow for depositing Si C interlayer, the fracture toughness of four groups of Si C/DLC composite films will increasing, gradually.