Study On High Temperature Resistant And Room Temperature Cured Organosilicon Coatings For Titanium Alloys

In order to protect the titanium alloy parts used in the high temperature environment,it has the advantages of simple,quick and low cost to paint the high temperature resistant coating on the surface.The current silicone high temperature resistant coatings have poor curing performance at room temperature and usually need secondary curing at 120?250?.In this paper,the technology of high temperature resistant organosilicone coating with high adhesion under normal temperature curing was studied,and the coating has good high temperature resistance.Through the performance evaluation of 22 resins,1 silicone resin and 2 epoxy-modified silicone resin were screened for in-depth study.Epoxy-modified organosilicone cured with polysilazane has a pot life of 0.5h?1h and a dry time of 1d.The hardness,cohesion strength and solvent resistance of the coating increase with the increase of polysilazane content.When the mass ratio of epoxy-modified silicone to polysilazane was 5:1,the residual mass of coating at 800? was 48.49%.The residue of 800?×1h was amorphous SiO2.and epoxy-modified organosilicon resin alone and by blending were studied.The results showed that the mechanical properties and heat resistance of the varnish were between the two resins,and the higher the content of silicone resin,the better the heat resistance of the varnish.The higher the content of epoxy-modified organosilicon resin,the higher the adhesion,hardness and solvent resistance of the varnish.The addition of TEOS(tetraethoxysilane)to organosilicon resin was beneficial to improve the heat resistance,while the addition of TEOS to epoxy-modified organosilicon resin had little influence on the heat resistance.The residue of two kinds of varnishes after 600?×1h was amorphous SiO2.Three groups of resins were used as the main film-former.The orthogonal method was used to test the amount of pigment filler.The basic mechanical properties and temperature resistance of organosilicone coating with packing dosage of SiC 5wt%,Al2O3 10wt%,talc 5wt%and mica powder 5wt%were good.Compared with the organosilicone coating,the solvent resistance and cohesion strength of the epoxy-modified organosilicone mixed with organosilicone coating with the filler dosage of SiC 10wt%,Al2O3 10wt%,talc 10wt%and mica powder 5wt%were improved,while the heat resistance was decreased.Epoxy-modified organosilicone coating with packing amount of SiC 6wt%,Al2O3 9wt%,talc 9wt%and mica 9wt%had better mechanical properties,solvent resistance and cohesion strength,but poor temperature resistance.The effects of different surface treatments on coating adhesion of titanium alloy substrate were studied.The results showed that the surface roughness of the titanium alloy after sand blasting was decreased after 400?×4h,the pure water contact angle was close to 0°,and the coating adhesion was improved.After laser processing,the adhesion of coating on the substrate surface was basically the same as that after sand blasting.