Research On The Preparation And Tribological Property Of Diamond Film By HF-CVD

Diamond film has drawn an intensive concern as a potential ideal tribologicalcoating in industrial applications for various precise mechanical components due to itsunique properties like the highest hardness and heat conductivity, good chemicalstability and etc. But the problem is that poor adhesion between diamond film andsubstrate of cemented carbide usually results in an early tool failure whichsubsequently damages the workpieces being processed. Therefore, improving theadhesion between diamond film and cemented carbide is very important. In this paper,diamond films with good adhesion were synthesized using composite interlayer in aHFCVD （Hot-filament Chemical Vapor Deposition）. On the basis of the coatingconcept of composite interlayer in combination with architecture design of multicomponent, functionally gradient and composite, a diamond film thick to153μm wassynthesized using a SiC interlayer in an online HFCVD （Hot-filament ChemicalVapor Deposition）, and diamond films with Ti based interlayer were synthesized usinghybrid deposition techniques. The deposition technology, microstructure, constituentof Ti based interlayer and the microstructure, mechanical and tribological propertiesof the diamond films were investigated. The following results were obtained:（1） The diamond film thick to153μm was synthesized using a SiC interlayer in anonline HFCVD process. The film exhibited a well-grown and dense columnarstructure in the depth direction. An approximately7-μm-thick intermediate SiC layerbetween the film and substrate improves the film adhesion effectively and is favorablefor depositing diamond film. Raman spectrum indicated that the film possesses adistinct diamond nature and is mainly composed of diamond crystallites in quality,and the residual stress of the diamond film is low （0.397GPa）. The averagecoefficient of friction in dry friction was about0.134, whereas an extremely lowcoefficient of friction （⁰.0413） in oil lubrication was achieved as well. The mainwear mechanism of the composite films during dry friction was micro-fracturing andpolishing.（2） The diamond films were synthesized using HFCVD and multi-function ion implantation equipment. The surface cobalt element of samples with acid etching, ionimplantation processing, implantation and intermediate layer processing, can all bewiped off effectively. Sample D₁（acid etching） did not get continuous diamond film.Sample D₂（ion implantation processing） and D₃（implantation and intermediate layerprocessing） obtained continuous diamond films. The films exhibited a well-grown anddense columnar structure. Raman spectrum indicated that the film possesses a distinctdiamond nature and is mainly composed of diamond crystallites in quality. Theresidual stress of sample D₂and the D₃were4.42GPa and1.36GPa. The frictioncoefficient curves of films are similar. The average friction coefficient of sample D₂and D₃in dry friction are0.15and0.17.（3） Attempting to reveal systemically some mechanisms likely causing the pooradhesion; illuminates and compares some approaches by using energetic-particles toform a multilayered gradient coating system so as to improve the adhesion, whichdemonstrates certain superior merits.