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为了提高可多次使用的二氧化硅表面绝缘涂层的使用温度,对该涂层进行了实验室研宄。根据合同 NaS 2-9809,改善的办法是增强涂层在再入大气层温度下的粘度,使涂层从地球轨道进入大气层时能承受空气动力学剪切力。在保留现有加涂方法和烧结工艺的情况下,增强涂层粘度的方法有三个:(1)减小各个涂层成分的粉末粒度;(2)减少粘度较低的涂层成分(B_2O_3);(3)添加粘度较高的玻璃成分(GeO_2)。试验表明:配合使用这三个方法所制成的涂层,与目前同类涂层相比有较高的表观粘度,能够满足目前航天飞机轨道器的要求。
In order to increase the service temperature of the reusable silica surface insulation coating, a laboratory research was performed on the coating. Under contract NaS 2-9809, improvements have been made to increase the viscosity of the coating at re-entry atmospheric temperatures and to withstand aerodynamic shear forces as the coating enters the atmosphere from Earth’s orbit. There are three ways to enhance the viscosity of the coating while preserving the existing coating and sintering processes: (1) reducing the particle size of the individual coating components; (2) reducing the viscosity of the coating component (B 2 O 3) ; (3) adding a high viscosity glass component (GeO 2). Experiments show that the coating prepared by using these three methods has high apparent viscosity compared with the current similar coating and can meet the requirements of the current space shuttle orbiter.