The sulfidation/oxidation of armco iron-based superalloys between 1023 and 1373 k
- PDF / 1,967,504 Bytes
- 9 Pages / 603.28 x 783.28 pts Page_size
- 26 Downloads / 154 Views
I.
INTRODUCTION
INCREASING the efficiency of thermal electric power plants while maintaining an economically viable condition requires using the highest possible temperature and cheapest possible fuel. Operating at a temperature above the present limit in the presence of sulfur activity gives rise to the problem of high temperature hot corrosion of materials. The design of gas turbines, jet engines, coal gasifiers, and other high temperature equipment for service beyond the present operating temperature is severely limited by materials availability. One typical example is the design of aircraft gas turbine material in which the hot corrosion resistance of material is greatly reduced when mechanically stronger materials are developed by reducing the chromium content of the alloy, t The sulfidation/oxidation of metals or alloys in simulated gaseous environments using SO2, SO2/O2, H2S/air, or SO2/air, e t c . has been extensively studied. The major corroding species of these gaseous mixtures are oxygen and sulfur which under most circumstances give oxide and sulfide solid products. The evaluation of alloy behavior under these conditions is important, especially for those containing appreciable amounts of nickel. Since the operating temperature is high, the nickel is thought to react with sulfur to form the molten reaction products. The molten slags accelerate the corrosion rate by providing the fast transport path and also reducing the ability of the oxide scale to adhere to the metal or alloy. In this work, the corrosion of two kinds of Armco superalloys under SO2/O2 atmospheres has been studied between 1023 and 1373 K using thermogravimetric analysis and metallographic examination. The Armco 18SR alloy has been tested for high temperature service in coal gasification TAI-KANG LIU, formerly Graduate Fellow, Department of Chemical Engineering, Iowa State University, is now Senior Engineer, Chung Shan Institute of Science and Technology, P.O. Box 1-4, Lung Tan, Taiwan, Republic of China. RENATO G. BAUTISTA is Group Leader. Ames Laboratory, USDOE, and Professor, Department of Chemical Engineering, Iowa State University, Ames, IA 50011. Manuscript submitted February 16, 1983. ME-I'ALLURGICALTRANSACTIONS B
environment. 2 The corrosion data are analyzed using empirical kinetic models and the results compared with previously reported related studies. Mass transport correlations are used to predict the volatilization rates of the protective Cr203 layer for temperatures above 1173 K, and the results are compared with the available literature data.
lI.
EXPERIMENTAL
The Armco 18SR and Armco T310 samples, with dimensions 0.127 x 2.54 x 5.08 cm, were supplied by Armco Steel Corporation Research Laboratory. A hole was punched at one end of the plate sample prior to the heat treatment carried out by the Armco Steel Corporation. The details of the heat treatment history are given in Table I. The chemical analysis of the sample, as reported by Armco, is given in Table II. These samples were not pretreated before corrosion testi
Data Loading...
