Development of Protective Coatings for Ceramic Tubular Components. Topical Report March 1986-December 1987

摘要

Process technology was developed for the deposition of adherent ceramic oxide coatings on silicon-based substrates for corrosion protection of ceramic heat exchanger tubes operating in aluminum remelters. Single- and multi-layer coatings of mullite, zircon, alumina, yttria and yttria stabilized zirconia remained adherent and intact after isothermal heat treatment at 1093 deg C/120 hours followed by cyclic heat treatment between 1010 deg C and 371 deg C (60 one hour cycles). Ten optimized coating compositions were deposited on alpha-SiC and SCRB-210 tubes for environmental exposure testing in a simulated aluminum remelt environment. An aluminum reclamation simulator was designed, constructed, and installed under the program. A computer simulation study was undertaken to characterize the gas phase chemistry in the aluminum remelt environment and to predict the nature of the corrosion products at the silicon-based tube surfaces. Mechanical properties of coated and uncoated tube specimens were determined.