SCIENTIFIC AND TECHNICAL AEROSPACE REPORTS

A Biweekly Publication of the National Aeronautics and Space Administration
VOLUME 44, ISSUE 5 - March 10, 2006

24 COMPOSITE MATERIALS
Includes physical, chemical, and mechanical properties of laminates and other composite materials.

20060007584 SRI International Corp., Menlo Park, CA, USA

Diffusion Coatings for Corrosion-Resistant Components in Coal Gasification Systems. Quarterly Report, January 1, 2005-March 31, 2005

Krishnan, G. N.; Malhotra, R.; Alvarez, E.; Lau, K.; Sanjurjo, A.; Sep. 2005; 22 pp.; In English Report No.(s): DE2005-860324; No Copyright; Avail.: Department of Energy Information Bridge

Heat-exchangers, particle filters, turbines, and other components in integrated coal gasification combined cycle system must withstand the highly sulfiding conditions of the high-temperature coal gas over an extended period of time. The performance of components degrades significantly with time unless expensive high alloy materials are used. Deposition of a suitable coating on a low-cost alloy may improve its resistance to such sulfidation attack, and decrease capital and operating costs. The alloys used in the gasifier service include austenitic and ferritic stainless steels, nickel-chromium-iron alloys, and expensive nickel-cobalt alloys. During this reporting period, we conducted several exposure tests with coated and uncoated coupons including a 500-h test. The first experiment was a 316-h test and was designed to look at the performance of Ti/Ta nitride coatings, which seemed to fare the best in earlier tests. The next experiment was a 112-h test with a range of pure metals and commercially available materials. Its purpose was to help identify those metals that best withstood gasifier environment, and hence should be good ingredients for coatings. Finally, we ran a 500-h test, which was also our milestone, with coupons coated with Ti/Ta nitride or Cr/Al coatings. NTIS

Coal Gasification; Corrosion Resistance; Diffusion

Source: NASA