Abstract
With the improvement of space technology，the speed of the space plane is faster and faster，so the structure of antenna mask should to be tough external bad environment effect. Therefore, it is necessary to use high temperature resistant coating to protect it and make it have high strength, good resistance to oxidation and corrosion resistance. But the heat resisting temperature of the high temperature resistant coating in existence is under 700 ℃so our country desperately needs the high temperature resistant coatings with higher heat-resisting temperature. The prepare of high temperature resistant coating is more and more urgent.
This paper studies the high-temperature organ silicon coating’s formula and mechanism. The organic silicone is used as the film former of the high temperature resistant coating, and talcum powder, mica powder, kaolin, titanium dioxide, silica and alumina as inorganic filler. By testing the high temperature resistant properties, mass loss in high temperature, hardness, water resistance and adhesion of the coatings with different inorganic filler amount, the best proportion of the organic silicone resin and inorganic filler is 40:60. The high-temperature coating performance test results showed that the optimum HIT-1 formula is as following: the silicone resin 20g, talcum powder 7.05g,mica powder 3.75 g, kaolin 15g, titanium dioxide 3.75g, silica 0.45g and the proper level of toluene. The high temperature resistant coating’s hardness is 4 H, the heat-resistant temperature is 600 ℃ ~700 ℃and the thickness is between 0.2 mm and 0.3 mm. According to the provident of the HIT-1 formula, the optimum HIT-2 formula is as following: the silicone resin 20g, talcum powder 7.05g,Al2O3 3.75g, kaolin 15g, titanium dioxide 3.75g, silica 0.45g and the proper level of toluene. Coating performance test results show that the heat-resistant temperature is 800 ℃ ,the hardness is 6H,the attached force level is 2 and the water resistance is good. The coating surface and component of the HIT-2 coatings which are cured and high temperature treated are analyzed by SEM, FT-IR,XRD, TG. The high temperature resistant principle is that: in the low temperature, the silicone resin can bear high temperature itself; In high temperature, the main chain of the silicone resin is broken. The Si-O short chains that sit on the surface act as the scaffold of the coating and form an inorganic silicon layer. The reaction between the inorganic yield the Al2(SiO4)O which is excellent high temperature materials. And the Al(OH)3 which has a low melting point may play a healing role in the coating.
Keywords: High-temperature coating, Silicone, Inorganic filler, High-temperature resistant mechanism
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