Research On The Preparation Of Diamond Film By MPCVD And Its Surface Treatment

Diamond is a typical multifunctional material which has excellent optical,mechanical,thermal,and electrical properties,and it has excellent application prospects in high-tech fields such as aerospace,energy,and precision machining.However,natural diamonds are very rare and expensive,and they are mostly used in the luxury sector such as jewelry.The diamonds prepared by the method of high temperature and high pressure are mostly granular,with many defects and impurities,and they mostly used in the grinding field,and the above factors limit the application of diamond in high-tech.The chemical vapor deposition(CVD)method can produce large-size and high-quality diamond films meeting the application requirements of high-tech fields at low production costs,which has attracted the attention of various countries.Microwave Plasma Chemical Vapor Deposition(MPCVD)has become the preferred method of preparing high-quality diamond films by virtue of its advantages such as high energy density and cleanliness.In this paper,the self-developed MPCVD equipment was used to explore the influence of working pressure,temperature of substrate,concentration of carbon on the diamond film forming process,and the optimal growth process of micron diamond film was obtained,and we obtain a high quality diamond film preparation process suitable for this equipment.The surface modification of the diamond film was carried out by high temperature oxidation method,and the influence of the terminal structure and micro morphology of the sample surface on the hydrophobicity was explored.Porous diamond films were successfully prepared by etching diamond films with hydrogen and argon plasma spheres,which is based on the principle of metal active catalysis,and the formation mechanism of porous diamond films was systematically analyzed.Using a 3 kW/2450 MHz microwave plasma chemical vapor deposition system,we study the influence of working pressure,temperature of substrate and concentration of methane on the growth rate and quality of diamond film by single factor experiment method.The results show that:The temperature of substrate and working pressure have the best critical values to affect the quality of diamond films,and the increase of concentration of methane is not conducive to the growth of high-quality diamond films.Considering the growth rate and quality of micron-sized diamond film,the optimal preparation process is as follows: temperature of substrate is 850 ?,working pressure is 14 k Pa,concentration of methane is 2.5%.Under these conditions,the growth rate of diamond film is 1.706 um/h,and the purity of diamond film is 87.92%.The surface modification of micron diamond film was carried out by high temperature oxidation method.The results show that: High temperature oxidation can significantly change the terminal structure and roughness of the diamond film surface,which results in significant changes in the hydrophilicity of the samples.Under the conditions of 400 ?,500 ? and 600 ? for 20 min,the contact angle of the samples decreases from 96° to 29°,showing obvious hydrophilicity.The porous diamond film was successfully prepared by plasma metal catalysis.The results show that: When the etching temperature is lower than 600 ?,the etching effect on diamond film is weak,and there is no pore formation on the surface.When the etching temperature is higher than 700 ?,the etching effect on diamond film is stronger,and porous diamond film can be prepared by proper treatment time.However,the density of pores is not positively correlated with the etching time,but it increases first and then decreases with the increase of etching time.