Study Of Carbon Film Coated On Micro Needle Of Irregular Surface

The micro needle which is used to punch the spinneret is easy to wear and tear during the punching process,which affects the production efficiency and benefit.In order to improve the working life of the needle,two kinds of superhard carbon-based thin film with strong wear resistance,low surface roughness are designed,the two technical routes include:（1）two step deposit diamond film,first deposit Ti N as transition layer by medium frequency magnetron sputtering,then deposit diamond film by hot filament chemical vapor deposition.（2）DLC thin films prepared by multi arc ion plating.In addition,the presence of an external field during the coating process will have a sharp effect at the tip of the different surface,affecting the substrate itself and the film on it.The influence of deposition parameters on the surface properties of the films as well as the influence mechanism of the tip effect produced by the micro needle in the outfield were both studied.The results obtained were as following:（1）Different N₂ flow rates affect the surface morphology,roughness and film substrate adhesion of Ti N transition layer.When the N₂ flow is 35 sccm,the surface performances of the Ti N film are the best.The roughness is 1.63 nm which is the lowest,the film is the most uniform and dense,and the adhesion between film and substrates is 21.8 N which is the highest.The diamond films were deposited on the steel plate coated with Ti N transition layer by changing the substrate temperature.Both the growth of diamond and graphite,and the growth of diamond and graphite by hydrogen plasma etching,which form a dynamic balance process,control the growth of diamond films.The substrate temperature has a significant effect on the growth and surface morphology of diamond.（2）The presence of electric field and thermal field in diamond films prepared by two step method has a sharp effect on the substrate and film quality.When the cleaning bias magnetron sputtering in more than 700 V,the tip deforms under the strong electric force;influence of HFCVD tip effect for molecular thermal motion makes the internal free charge at the tip position increased,additional tip temperature affect diamond nucleation and growth.Leading to the film nonuniform.（3）The surface morphology and roughness of DLC thin films were affected by the bias voltage in the DLC films prepared by multi arc ion plating.Properly increasing the substrate bias is helpful to reduce the droplet on the film surface and improve the uniformity and density of the film.The field experiments showed that the needle size and surface roughness deposited by multi arc ion is worse than magnetron sputtering,while the the needle punching properties of magnetron sputtering deposition is better.