CERAMIC COATINGS THAT INCREASE WEAR-RESISTANCE AND SUPPRESS THE IGNITION OF 316-STAINLESS-STEEL IN AN OXYGEN ENVIRONMENT

Many materials that are not considered to be flammable in air can igni te and burn in oxygen environments, for example stainless steel (SS) w ill burn vigorously when ignited in a 1000 psi (6.9 MPa) oxygen enviro nment. Advancing technology is creating a demand for higher oxygen-use temperatures and pressures, e.g. NASA propulsion systems. Fires in ox ygen systems are generally catastrophic, causing damage to equipment a nd a threat to life. Aluminosilicate (47 wt.%) coatings were applied t o 316 SS substrates using sol-gel techniques; a proprietary coupling a gent effects covalent bonding. Coated coupons were subjected to six 60 0 degrees C s(-1) thermal quench cycles with no interface failure and the coatings did not crack. The aluminosilicate coating reduced wear r ates by 88.2% and 52.9 % For 50 g normal force and 150 g normal force, respectively. There is no decrease in substrate biflexure strength wi th processing of the aluminosilicate coating. Coated and uncoated spec imens were subjected to frictional heating experiments in an oxygen en vironment at the White Sands Test Facility. Aluminosilicate coatings s uppress the ignition of 316 SS; measured pressure-velocity products ar e independent of coating thickness and appear to be composition depend ent.