Study On Preparation And Performance Of Hydrogenated Diamond-like Carbon Films And Its Silicon Doped Films

Diamond-like carbon（DLC）film,a unique material with properties between diamond and graphite,has attracted great attention due to its extraordinary mechanical properties,high electrical resistivity,biological compatibility and optical transparency.It is expected to be useful in a wide range of fields,such as aerospace,automotive,optical and bio-medical,etc.However,the structure of a-C:H normally reorganizes and the properties are transformed from diamond-like to graphite-like by overheating.Therefore,some advantages are subjected because of the poor thermal stability of a-C:H and it becomes a crucial issue for the achievement of the anticipatory properties for applications.The hydrogen in carbon film is important to the property of thermal stability,and the effusion behavior of hydrogen with rising temperature in amorphous carbon is an important subject.The silicon is always doped in a-C:H film,as a very efficient method,to improve the thermal stability.However,it is still unclear how the silicon affects the effusion of the hydrogen and the characteristics of films with annealing treatment.Therefore,plasma-enhanced chemical vapor deposition was used to make a-C:H film to study the effects of hydrogen on the film.The 316L stainless steel,aluminum foil,and single crystal silicon（100）wafer were prepared as substrates and were deposited by films.The effect of hydrogen on micro-structure,micro-morphology,mechanical properties of films were discussed.The results showed that hydrogen was mainly existed in forms of atoms or molecules.The graphitization course was divided into two stages prominently on account of unbonded hydrogen emission from the a-C:H film.Besides,the emission of hydrogen at564°C induced a pronounced relief of compressive stress and a facilitated graphitization process.Structural changes and the H₂ emission resulted in a peculiarity of the linear reordering on film surface at high temperatures,and gradient descent of nano-hardness and compressive stress degradation.Insufficient thermal activation resulted in nonoccurrence of crystallization during the annealing procedure.Plasma-enhanced chemical vapor deposition was used to make a-SiC:H to study the effects of doped silicon on films.The results showed that hydrogen in films was mainly unbonded with carbon atoms.The effusion temperature of hydrogen was improved to 600°C.However,as the annealing temperature rose up,doped silicon element tend to transform from SiC to SiO_x,and the stabilization effect of silicon disappeared when the annealing temperature rose up to 530°C.The friction coefficient rose up due to the structural changes from SiC to SiO_x with annealing treatment.