Codeposition of Metals for Oxidation Protection Above 2200C (Phase 1).

摘要

Engel-Brewer intermetallic compounds are notable for their chemical stability and high melting points. These properties suggest their potential usefulness as oxidation-resistant coatings for rocket engine components operating at 2400 C. The objective of the program was to investigate the feasibility of producing Engel-Brewer compounds by chemical vapor deposition (CVD), and to characterize the oxidation and refractory properties of the materials. Attention focused on iridium aluminide. Researchers attempted codeposition of iridium and aluminum in the desired proportions using alkyl precursors for the aluminum and beta-diketonates for the iridium. The approach was unsuccessful because of precursor incompatibility. Applying alternating layers of iridium and aluminum, followed by diffusion at a temperature sufficiently high to promote homogenization, produced an iridium aluminide coating which is adherent to both rhenium and molybdenum, and is more oxidation-resistant than iridium alone.