Study On Structure And Properties Of Hf-doping Diamond-Like Films Prepared By Magnetron Sputtering

In this article,magnetron sputtering DC and RF co-deposition techniques were used to modify the diamond-like carbon(DLC)films by doping with foreign elements.The influence of different low-level of hafnium(Hf,<1 at.%)on the composition,structure and mechanical properties of DLC films was studied.At the same time,the composition and microstructure of Hf-DLC films under nitrogen atmosphere were investigated.The influence of different nitrogen flow ratio(R)on the optical properties was also analyzed.The main findings are as follows:Different content Hf-doped DLC films,namely Hf-DLC thin films,were prepared by adjusting DC Hf target voltage and current.It was found that the main form of Hf in DLC films is hard HfC nanocrystals;with the increase of Hf content,the root mean square roughness(R_q)of Hf-DLC films increases from 6.9 nm to 22.1 nm;The deposition rate is about 9.55 nm/min.In addition,the sp~3/sp~2 ratio in the Hf-DLC films increases first and then decreases from 0.56 to 1.01,and reaches the maximum when the doping Hf content is 0.42 at.%.Then,Hf-doped DLC films,i.e.,(Hf:N)-DLC films,were prepared under nitrogen atmosphere.The effects of non-metallic N-doped Hf-DLC films on their composition and structure with different R conditions were studied.It was found that with the incorporation of N elements,the elements Hf and N enter the DLC films mainly in the form of HfN,while N exists in the DLC films in the forms of NO,-CN_x(x=1,2,3)and N-Hf.With the increase of R,the Rq of the(Hf:N)-DLC films increases from 7.43 to 12.73 nm,but the overall surface roughness is improved,and the average deposition rate of the films decreases to 6.83 nm/min.In addition,the I_D/I_G ratio increased from 2.18 to3.37.From the above,the Hf-doped DLC films affected the composition and microstructure of the carbon matrix,and the incorporation of N also changed the dominant form of Hf in the carbon matrix.The study of mechanical and tribological properties of low content Hf-doped DLC films.The results show that with the increase of Hf content,the hardness and elastic modulus of Hf-DLC films decrease firstly,then increase and finally decrease,while the friction coefficient and wear life are opposite to each other.When the Hf doping content is 0.42 at.%,the Hf-DLC film exhibits excellent tribological behavior with a hardness of 1.32 GPa and an elastic modulus of 15.42 GPa.It is mainly attributed to the dual role of HfC structure in DLC films,namely the presence of hard carbides,which can also destroy the overall structure of the carbon network.The structure and optical properties of(Hf:N)-DLC films under different R conditions have been studied.The results show that with the increase of R,the visible light region transmittance of DLC films is as high as 95%,and the bandgap(Eg)width is between 1.84 and 2.01 eV and decreases with increasing R.The main reason is that with the incorporation of N,the content of sp~2~C in the(Hf:N)-DLC films increases,the cluster increases and the degree of order increases,resulting in a corresponding decrease in Eg,i.e.,the incorporation of N element into Hf-DLC films can effectively regulate the optical band gap of the films.