DTIC ADA072645: Hot Corrosion Degradation of Metals pdf

DTIC ADA072645: Hot Corrosion Degradation of Metals

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The hot corrosion attack of metals and alloys has been examined over an extensive range of experimental conditions in order to develop a hot corrosion theory. Experiments have been performed at temperatures from 700 to 1000 C in air and in gases containing oxygen and SO 3. Sodium sulfate was the principal deposit used to induce attack and the effects of NaCl and carbon in the Na2SO4 was also studied. Nickel- and cobalt-base alloys containing various amounts of chromium, aluminum, molybdenum and tungsten constituted the principal materials studied. The hot corrosion attack of alloys has been found to consist of an initiation stage and a propagation stage. The factors which determine the length of the initiation stage and the type of propagation mode are shown to be; alloy composition, fabrication condition, gas composition and velocity, salt composition, salt deposition rate, condition of salt, temperature, temperature cycles, erosion and specimen geometry.

The hot corrosion propagation modes are described and shown to consist of fluxing processes and processes involving the oxidation of phases formed in alloys as a result of reaction with components in the deposit (e.g. sulfides, chlorides). The effects produced by a number of different elements (e.g. Cr, Al, Mo, W) on the hot corrosion of alloys is examined. It is shown that by using the unified theory for hot corrosion, previous inconsistencies are resolved

• Creator/s: Defense Technical Information Center
• Date: 6/1/1979
• Year: 1979
• Book Topics/Themes: DTIC Archive, Giggins, C. S., PRATT AND WHITNEY AIRCRAFT MIDDLETOWN CT MATERIALS ENGINEERING AND RESEARCH LAB, *CORROSION, *GAS TURBINES, *NICKEL ALLOYS, *SUPERALLOYS, *COBALT ALLOYS, *CORROSION RESISTANT ALLOYS, *CHROMIUM ALLOYS, DEGRADATION, AIR, HIGH TEMPERATURE, MOLYBDENUM, CARBON, OXYGEN, ALUMINUM, CHROMIUM, SODIUM CHLORIDE, TUNGSTEN, SULFUR OXIDES, CORROSIVE GASES, SODIUM SULFATES

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