Preparation And Properties Of Heat Resistant Adhesives With Broad Working Temperature Range

With the development of science and technology,many fields such as aerospace,nuclear engineering as well as other energy factories are involved in extremely high temperature environments,it is necessary to produce novel heat?ultra high temperature?-resistant materials,innovate and upgrade thermal protection or heat sealing systems.Heat-resistant adhesives play decisive roles in terms of component preparation,thermal protection system installation,as well as component repair.However,due to the decomposition of organic polymer in the medium temperature,the ceramic conversion reinforcement is insufficient,so the adhesive keeps very low bonding strength,which is not conducive to safe bonding.In this paper,the compensation mechanism of the bonding strength of heat resistant adhesive at intermediate temperature was studied,and the bonding strength of the adhesive over 1000 centigrade degree was improved by using modification technology:?1?Based on poly methyl silicone resin as matrix,the ratio of Si/Al and the content of B₄C was adjusted to compensate the shrinkage of the adhesives,provide bonding strength through capillary force of liquid phase andpromote the formation of high melting point glass and heat resistant ceramic phase mullite.The shear strength of SiC joints bonded by the adhesive were 39.31±1.37MPa after heat-treatment at1100^oC.Meanwhile,the“weak bonding stage”from 400^oC to 600^oC of the adhesive was compensated to some degree.?2?Based on the modification with blending and copolymerization,the cross-linked interpenetrating network was formed,and the cross-linked molecular chain was extended which improvedthe heat resistance of polymer and help to form the"cross zone"and eliminate the"weak bonding stage".As a result,the adhesive with wide working temperature range was prepared,which ensured the bonding safety.Epoxy resin can effectively blend and copolymerize with silicone resin,effectively compensating the"weak bonding stage"from the 400^oC to 600^oC of the prepared adhesive.What's more,the shear strength of the prepared adhesive tested at room temperature after heat-treatment at different temperature from room temperature to 1500^oC were higher than 9.29±0.56MPa,and the shear strength of the adhesive directly tested from room temperature to 800^oCwere higher than that of8.21±0.40MPa.Phenolic resin didn't copolymerize with silicone resin does,but due to the high compatibility of the adhesive after the carbonization of phenolic resin,the decreasing of bonding strength of the adhesive from 1100^oC to 1500^oC wasalleviated.