Advanced Porous Coating for Low‐Density Ceramic Insulation Materials

Abstract

The need for improved coatings on low-density reusable surface insulation (RSI) materials used on the space shuttle has stimulated research into developing tougher coatings. The processing of a new porous composite "coating" for RSI called toughened unipiece fibrous insulation is discussed. Characteristics including performance in a simulated high-speed atmospheric entry, morphological structure before and after this exposure, resistance to impact, and thermal response to a typical heat pulse are described. It is shown that this coating has improved impact resistance while maintaining optical and thermal properties comparable to the previously available reaction-cured glass coating. [

Microstructure, radiative property and thermal shock behavior of TaSi2–SiO2-borosilicate glass coating for fibrous ZrO2 ceramic insulation

“…Until now, several high emissivity coatings have been developed for the application of thermal protective systems [10,11], thermal furnaces [12] and other high-temperature processing units for the purposes of energy savings [13,14], such as SiC and SiC based composites [6,[15][16][17][18], rare-earth oxides [7,10,[19][20][21], refractory metal silicides [22], transition metal oxides [23,24], cordierite structure systems [25,26], perovskite-type systems [13,27,28], magnetoplumbite structure systems [29][30][31][32] and metallic systems [33,34]. In addition to the pursuit of high M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPT 5 emissivity, other properties such as thermal shock resistance and oxidation resistance, should also be considered when high emissivity coatings are used at high temperatures. However, single component coatings rarely possess these comprehensive properties.…”

“…A reusable thermal protective system ( Fig. 1) consisting of a high emissivity coating used on the surface and a low thermal conductivity insulation used inside could decrease the surface temperature by radiation and prevent heat transfer via thermal conduction [1,5]. A mathematical model proposed by Van Wie [3] suggested that under identical heat flux the wall temperature of a hypersonic vehicle is reduced by 573 K when its surface emissivity is increased from 0.5 to 1.0 at Mach 10.…”

Study on Sintering Behavior of Reaction-Cured Glass Coating

“…The top surface and four sides of each insulator usually need to be covered with a high-emissivity coating, which could reduce the surface temperature by radiating heat toward the surrounding environment [7][8][9][10]. Therefore, high-emissivity coatings with reliable performance are an indispensable and critical part of TPS [11].…”

“…SiB 4 is considered a processing aid and emittance agent. After that, a new generation of toughened uni-piece fibrous insulation coating (TUFI) was developed on the basis of RCG for mechanical property requirements [11,13]. Compared with the past coatings, the composition and structure of TUFI have changed.…”

Improved oxidation resistance of high emissivity coatings on fibrous ceramic for reusable space systems

“…Consequently, HEC materials with similarly high thermal stability are sought to complement fibrous ZrO2 insulation materials in RTPSs. 2 mullite and ZrO2 ceramics, with favorable emissivity levels of 0.85 and higher achieved [3][4][5][6][7][8][9][10]. In our previous work, MoSi2-borosilicate glass coating prepared on fibrous ZrO2 ceramic showed excellent thermal shock behavior between room temperature and 1673 K [8], and following the inclusion of ZrO2 in the coating material, this thermal shock resistance was extended to 1773 K [9].…”