Ceramic coatings that increase wear resistance and suppress the ignition of 316 stainless steel in an oxygen environment

Abstract Many materials that are not considered to be flammable in air can ignite and burn in oxygen environments, for example stainless steel (SS) will burn vigorously when ignited in a 1000 psi (6.9 MPa) oxygen environment. Advancing technology is creating a demand for higher oxygen-use temperatures and pressures, e.g. NASA propulsion systems. Fires in oxygen systems are generally catastrophic, causing damage to equipment and a threat to life. Aluminosilicate (47 wt.%) coatings were applied to 316 SS substrates using sol-gel techniques; a proprietary coupling agent effects covalent bonding. Coated coupons were subjected to six 600°C s -1 thermal quench cycles with no interface failure and the coatings did not crack. The aluminosilicate coating reduced wear rates 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 with processing of the aluminosilicate coating. Coated and uncoated specimens were subjected to frictional heating experiments in an oxygen environment at the White Sands Test Facility. Aluminosilicate coatings suppress the ignition of 316 SS; measured pressure-velocity products are independent of coating thickness and appear to be composition dependent.