Preparation of metakaolin based geopolymer coatings on metal substrates as thermal barriers

Pigments and binders for obtaining radiation-resistant thermal-control coatings (TCC) for spacecraft were studied. A radiation-resistant thermal-control coating was obtained on the basis of the chosen components. The 15-year resistance of the coating in a geostationary orbit (GSO) was evaluated on the basis of ground-based tests. The comparative characteristics of white TCC (based on BaSO4), which are currently the most widely used coatings in Russia, are presented.

Liquid-Glass Radiation-Resistant Thermal-Control Coating

Water-glass-based pastes show good prospect for high-temperature applications, but they are subject to substantial dry-shrinkage. Silicon and aluminum powders were added to prevent the dry-shrinkage. The influence of them on compressive strength, bonding strength and volume of the pastes was discussed. SEM, XRD, and TG/DSC were employed to study the influencing mechanisms. The results show that Si and Al effectively prevented the dry-shrinkage; Al improved compressive strength and bonding strength, while Si was bad for bonding strength. When Al dosage was 6%, the pastes presented mild expansion of 1.05%, the compressive strength increased by 8.9%, and the bonding strength by 33.4%.

Influence of expansion admixtures on the properties of water-glass-based refractory pastes

The effect of the silica modulus of water glass, functional additives, and mechanical activation of the filler on the composition of a fireproof composite is described. At temperatures up to 700°C one can decrease thermal diffusivity by the formation of a heat-insulating layer frothed by water vapor dehydrated from water glass. Within the high-temperature range heat-insulating properties are improved by the synthesis of nepheline in the reaction between sodium silicate and alumina. Mechanical activation of alumina improves this effect. Introduction of carbamide and boric acid additives improves the fireproof properties of the gaseous medium.

Fireproof water glass composite based on mechanically activated alumina

Moistening of filler particles with binder, curing, and high-temperature synthesis were studied in a liquid-glass formulation based on aluminum oxide. Selected kinetic parameters of these processes were determined. The influence exerted by the phase composition and mechanical activation on the adhesion, yield of the synthesis product, and basic properties of the formulation were analyzed.

V. Yu. Zelinskii

Papers

Fireproof water glass composite based on mechanically activated alumina

Properties of a fireproofing formulation based on liquid glass and mechanically activated aluminum oxide