Thermal protection systems (TPS) are a group of materials that are indispensable for protecting spacecraft from the aerodynamic heating occurring during entry into an atmosphere. Among candidate materials for TPS, ceramic insulation materials are usually considered for reusable TPS. In this study, ceramic insulation materials, such as alumina enhanced thermal barrier (AETB), are fabricated via typical ceramic processing from ceramic fiber and additives. Mixtures of silica and alumina fibers are used as raw materials, with the addition of B4C to bind fibers together. Reaction-cured glass is also added on top of AETB to induce water-proof functionality or high emissivity. Some issues, such as the elimination of clumps in the AETB, and processing difficulties in the production of reusable surface insulation are reported as well.

Recently, inorganic-organic hybrid materials have attracted much attention not only for their excellent thermal conductivity but also for their flame retardant properties. In this study, the properties of organic-inorganic hybrid insulating materials using inorganic fillers and polyurethane foam with different foaming conditions have been investigated. The addition of 1.5 wt% water to polyurethane as foaming agent shows the best foaming properties. The pore size was decreased in the foaming body with increasing of the CaCO3 addition. The apparent density and thermal conductivity were increased by increasing the CaCO3 addition. With an increasing amount of CaCO3 powder, the flame retardant property is improved, but the properties of thermal conductivity and apparent density tend to decrease. When the addition of fine particles of CaCO3, the apparent density and thermal conductivity were increased and, also, with the addition of coarse particles over 45μm in size, the apparent density and thermal conductivity were increased as well. In this study, the adding of CaCO3 with average particle size of 27μm led to the lowest thermal conductivity and apparent density. After evaluation with different inorganic fillers, Mg(OH)2 showed the highest thermal conductivity; on the other hand, CaCO3 showed the lowest thermal conductivity.

Insulation materials used for building save energy and can be classified into inorganic and organic materials. Organic insulation emits toxic gases in a fire annd has lower water resistance. Inorganic insulation is heavy and has poorer thermal performance than that of organic material. This study evaluated the physical properties and fire resistance of lightweight inorganic insulation foaming material made of waste glass powder. The test results showed that the inorganic material performed well with low density and low thermal conductivity for an insulation material. Foam insulation material manufactured from glass powder was sufficient as a fire-resistant product.