Preparation And Microstructure Properties Of PTFE/Ti Composite Coatings On Graphite

Graphite cookers have the advantages that traditional alloy cookers do not have because of its excellent electromagnetic induction heating efficiency,high thermal conductivity and corrosion resistance,and have a very broad development prospect.However,the non-stick coating prepared on the surface of graphite cookware has some shortcomings such as poor adhesion,and its practical application is limited.Therefore,how to improve the adhesion of non-stick coating on graphite cookware surface and increase the service life of coating is an important research direction.In this paper,titanium films were prepared on graphite by magnetron sputtering technology.The adhesion of the films was improved by optimizing the sputtering process parameters.Then,PTFE non-stick coating was prepared on the surface of titanium film as transition layer,so as to realize the preparation of PTFE/Ti composite layer on graphite surface.Firstly,the effects of sputtering power,sputtering pressure and deposition time on microstructure,surface roughness and adhesion of ti films were investigated by orthogonal experiments.The optimal sputtering parameters are as follows: sputtering power 200 W,sputtering pressure 1.2 Pa,deposition time 50 min.The titanium films prepared by using this parameter have good adhesion and the film thickness is 1.3 μm.The surface of the thin film is uniform and smooth without crack defects.The microstructure is island shape,the roughness Ra is 31.5 nm,and the particle size is about 150 nm.The titanium films have a dense hexagonal α-Ti structure and grow along the 002 crystal plane preferentially,which may be related to the lamellar structure of the graphite matrix.Secondly,in order to solve the problem of poor adhesion of PTFE/Ti composite layer,the effect of surface roughness of graphite matrix on microstructure and adhesion of PTFE/Ti composite layer was studied.The effect of deposition temperature on microstructure and surface roughness of ti films was also studied.The results show that the adhesion of PTFE/Ti composite is improved by increasing the surface roughness of the substrate,and 180# sand paper is the best choice for polishing the surface roughness.The particle size and undulation degree of ti film surface increase with the increase of substrate roughness.With the increase of deposition temperature,the surface roughness of titanium films increases first,then decreases,and then increases significantly.The appropriate deposition temperature is lower than 300 ℃.Finally,PTFE/Ti composite layer was successfully prepared on the graphite surface by using the above research results,and the microstructure and adhesion of the composite layer were characterized.The results show that the PTFE/Ti composite coating has a smooth surface,PTFE has a fiber network structure,and the non-stick coating is composed of the bottom layer,the middle layer and the surface layer.The middle layer is reinforced with Si C particles.The adhesion of PTFE/Ti composite layer is obviously higher than that of PTFE coating without transition layer.The existence of Ti transition layer improves the bonding properties of graphite matrix and non-stick coating.