Traceability Study On The Measurement Of Bonding Strength Of Hard Film By Scratch Method

With the development of coating technologies such as CVD,PVD and magnetron sputtering,thin film materials are increasingly used in tools,aerospace,semiconductor and other industries.The method of measuring the bonding strength between the film and the substrate by the scratch method is gradually accepted and applied by the industry as an effective measuring method for considering the quality and application reliability of the coating product.In order to ensure the accuracy,reliability and the equivalent of the magnitude of the bonding strength between the film and the substrate measured by the scratch method,it is necessary to establish a traceability system based on the scratch method to measure the film bond strength.The selected 304 stainless steel and M2 high speed steel are used as the substrates,and the diamond-like carbon is deposited film.The effects of different substrates,different film thicknesses and transition layers on the film-substrate bond strength are studied.The 304/DLC has a large depth of penetration,and the film and film-based interface failure occurs at a small force value.Finally,the film is largely detached and exhibits a clear base topography;the HSS/DLC has a small depth of penetration,and the failure of the film-substrate system occurs at a large load,and eventually the film peels off but adheres densely to the surface of the sample.Different thickness films have different internal stresses and are affected by the substrate effect.The thickness of the film has little effect on the bonding strength of the film-substrate system.After selecting the standard materials,the effects of different radii of curvature,scratch speed,load range and scratch length on the bond strength of the film-substrate system were investigated.As the speed of the stroke increases,the feature of the scratch is more obvious,and the critical force value can be accurately determined at 3 mm/min.The load range is set to the vicinity of L_c11 and L_c3 to determine the critical force value more accurately,and finally 3-15 N is selected as the measurement range of HSS/DLC-500nm.When the scratch length reaches 4.5 mm,the scratch appearance is the best.As the radius of curvature of the indenter increases,the critical load increases.The same force is applied.The larger the radius of curvature of the indenter,the deeper the position of the maximum stress point,and the more obvious the shape of the characteristic force value.The 200?m radius of curvature indenter was finally selected as the test indenter.After homogeneity,stability and repeatability analysis of HSS/DLC-500 nm and HSS/DLC-900nm,the critical load of the standard substance HSS/DLC-500 nm was determined to be L_c11 of 6501.19 mN,and the extended uncertainty was 372.82 mN,L_c2 is 8392.28 mN,the extended uncertainty is 394.46 mN.The critical load of HSS/DLC-900nm was determined to be L_c1 is 5033.45 mN,the expansion uncertainty is164.00mN,L_c22 is 7358.23 mN,and the extended uncertainty is 258.20mN.