Preparation And Performance Research Of Room Temperture Curable Paint-type Thermal Control Coatings

Thermal control coatings(TCCs)could well balance the surface temperature of spacecraft via its special thermophysical property of solar absorptance(?s)and emittance(?H).Paint-type inorganic TCCs with low ?s/?H value are the first choice of high-performance spacecraft because of their excellent spacial stability,however,these coatings have high curing temperature and brittleness.There are some types of room temperature curable organic TCCs.Yet,many organic TCCs have weak spacial stability,which are difficult to meet the demand of long-life spacecraft.In this work,a new kind of the organic-inorganic room temperature curable hybrid thermal control coatings has been successfully obtained by sol-gel method using silicon monomer as raw materials.The main results are as follows:(1)By systematically studing the hydrolysis/condensation dynamics of TEOS,the reaction regularity of TEOS in different conditions was further confirmed.Based on the above results,The room temperature curing mechanism was analyzed by researching the spontaneity of siloxane reacting at room temperature,which shows that it is feasible to prepare the room temperature curing binder.(2)The optimizing experiments scheme.The binder with different formulations of TEOS and siloxane were prepared by hydrolysis/condensation reaction with the controlling variate method and their room temperature curing performance were evaluated.In this way,the room temperature curable organic-inorganic hybrid binder was prepared.The as-prepared binder has abundant active hydroxys in its structures and the average polymerization degree of the binder is adjustable with the reaction condition and binder formulation changing.(3)The room temperature curing organic-inorganic hybrid TCCs with the best binder formulation were prepared by optimizing the spraying technology and sparing layer by layer.The binder and the pigment dispersed well on the coating surface.The coatings have low solar absorption ?S and high emittance ?.Moreover,the(4)coatings have excellent adhering capacity to both aluminum substrate and glass fiber reinforced plastic(GFRP).More DMDS in the coating increase the elasticity and more TEOS enhance their hardness and elasticity modulus.TGA test results show that the coatings have high thermal stability below the temperature of 200?,and it can be further increased by increasing TEOS and Zn O ratios.(5)According to the requirement of spacecraft to the spacial stability of TCCs when flying in the outer space,the vacuum-UV test,high-low temperature cycles test and humidheattest of the coatings were conducted using the specified method in the GJB standard.The surface appearance,solar absorptance and emittance of the coatings were measured.The results show that the as-prepared organic-inorganic hybrid TCCs has excellent stability under space environment.