S781 涂层分区喷涂色差分析与试验

为满足载人飞船返回舱的温度要求,需要在返回舱外壁喷涂S781热控涂层.若采用分区喷涂的方式,在搭接区域会出现色差.本文对S781热控涂层搭接色差进行了特性分析,并进行了不同温度、间隔时间和基材的验证试验.结果表明:色差是由于分区喷涂间隔时间大于涂层的表干时间引起的.分区间隔时间为1 min时没有色差,间隔时间越长,色差越明显；温度较高时,表干时间变短,色差更明显,且会出现大颗粒现象.将喷涂温度控制在20℃左右,分区间隔时间小于2 min,可以有效的减弱或控制色差.提出了一种返回舱热控涂层喷涂改进方法,可以有效的减弱色差.

Analysis and Experiments of Color Difference on S781Coating Partition Painting

In order to maintain the temperature of the reentry capsule, the S781 thermal coating is painted on
outside wall of the reentry capsule of manned spacecraft. In the painting process, the color difference appears between
the partition and adjacent partition. In this paper, the composition of color difference area of S781 coating is analyzed,
and several experiments are designed with different painting temperatures, interval time and materials. The result
reveals that the color difference is due to that the interval time of partition painting is longer than the surface drying
time of the coating. The color difference becomes obviously with the interval time, which is more than 1 minute.
And there are granules when the temperature is high, because the surface dries much more quickly. At last, an improved
painting method of S781 thermal coat is proposed to control the joint color difference. The result will be helpful
to the implement of thermal control of manned spacecraft.