Accession Number : AD0748349

Title :   Investigation of the Hot Corrosion Mechanism in Nickel-8 Chromium-6 Aluminum.

Descriptive Note : Master's thesis,

Corporate Author : AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OHIO SCHOOL OF ENGINEERING

Personal Author(s) : Adams,Nathan J. , Jr

Report Date : JUN 1972

Pagination or Media Count : 61

Abstract : The mechanism of hot corrosion in a nickel-chromium-aluminum alloy was investigated. The effects of three sodium salts (sulfate, carbonate, and nitrate) were studied at 100C in 150 torr oxygen; additionally, tests were conducted with sodium sulfate at 900C in oxygen and at 1000C in argon. Continuous gravimetric data were taken for each experiment; corroded specimens were analyzed using X-ray diffraction, metallographic, and electron microprobe techniques. The hot corrosion mechanism involves a sequence of events; formation of an oxide layer, formation of subsurface chromium sulfides, dissolution of the protective oxide scale, and oxidation of the sulfides and the chromium-depleted substrate. The role of sulfur in the hot corrosion process is the depletion of chromium in the alloy; the alloy is thus susceptible to increased oxidation. (Author)

Descriptors :   (*NICKEL ALLOYS, *CORROSION), ALUMINUM ALLOYS, CHROMIUM ALLOYS, SODIUM COMPOUNDS, SULFATES, THESES, HIGH TEMPERATURE

Subject Categories : Properties of Metals and Alloys

Distribution Statement : APPROVED FOR PUBLIC RELEASE