Influence Mechanism Of Low-temperature Deposited Carbide Interlayer On Diamond Film Growth

It is an effective way for the deposition of high performance diamond film that adding carbide interlayer between cemented carbide and diamond film, And the capabilities of interstellar drilling tools could be improved by diamond film.But the high temperature condition during CVD deposition will lead to interface coarsening and high density of defects in interlayer. The exploration of low-temperature deposition technology of carbide interlayer is important for the adhesion improvement between cemented carbide and diamond film.In this dissertation, the general situation and hotspot issues of research on cemented carbide diamond film are first reviewed. The focus of this dissertation lies in exploring the low temperature deposition method and influence mechanism of carbide interlayer between cemented carbide and diamond film. The studies on preparation procedures and performance of Si or Ti carbide interlayer deposited by mid-frequency sputtering and ion implantation have been carried out. The interaction between preparation procedures and performance of interlayer is systematacially discussed based on the analysis of interlayer’s composition, structure and adhesion performance. The impact of preparation process on the structure and adhesion properties of carbide interlayer and diamond film is investigated. The relationship between deposition proces of carbide interlayer and nucleation, growth, performance of diamond film is determined. The observations made in this work provide an effective and repeatable low temperature deposition technique for using such carbide interlayer on the improving of adhesion performance of diamond film. They likewise offer theoretical pointers for developing excellent cemented carbide tool coated with diamond film, and extended the use of cemented carbide tools in special machining and extraterrestrial exploration etc. The main original conclusions in this dissertation can be concluded as follows:1. SiC interlayers have been deposited by mid-frequency sputtering under different deposition temperature, bias, target current and flux of reactive gas. And the impact of deposition process on surface appearance, composition, structure and adhesion performance of SiC interlayer has been investigated. The results show that:the change of deposition temperature, bias, target current and flux of reactive gas(C2H2) have regularly influence on surface appearance, composition, structure and adhesion performance of SiC interlayer. SiC interlayer with suitable composition and structure for diamond film nucleation, growth and performance improvement could be achievement by coating design and process control.2. Diamond films are synthesized using HFCVD method on the surface of SiC interlayer deposited under different process parameters. The influence of SiC interlayer’s surface appearance, composition and structure on nucleation, growth and performance of diamond film has been analyzed. The results show that: theorganizational weaknesses, composition and structure of SiC interlayer have significant impact on nucleation and performance of diamond film. SiC interlayer which has high density, atoms ratio of Si and C closer to 1:1, and high β-SiC content is in advantage of obtaining good quality diamond film. β-SiC interlayer has significant promotion on nucleation and performance of diamond film. The whole procedure of diamond nucleation on β-SiC surface is composed of six parts:nucleation preparation stage, atomic activation stage, atomic replaced stage, nucleus formation stage, nucleus growth stage and diamond film growth stage.3. Thin TiC interlayers are prepared using ion implantation method on the surface of cemented carbide. The relationship between energy variation of Ti ion implantation and change of surface appearance, composition on cemented carbide surface are systematacially discussed. The role of thin TiC interlayer on nucleation,growth and performance of diamond film is investigated. The results show that: the variation of Ti ion implantation has regular influence on composition, structure and performance of thin TiC interlayer on the surface of cemented carbide. An ideal efficiency can be achieved when implant energy is 35 KV, and this thin TiC interlayer has positive effects on nucleation and adhesion property of diamond film.