Adsorption and Segregation of Sulphur, and its Influence on the Carburization and Nitrogenation of Iron and Steel

摘要: In the segregation studies equilibrium sulphur activity, as, was determined by concentration of dissolved sulphur. The results were correlated with surface reaction kinetics in carburization and nitrogenation iron presence adsorbed These performed a flow apparatus at atmospheric pressure, activity being established H2S/H2 ratio gas atmosphere. effect studied for reactions CH4(g) = C(dissolved) + 2H2(g) N2(g) 2N(dissolved) resistance relaxation method on thin foils 800-900 'C. Even bulk concentrations about 0.1 pag/g S, strongly retarded. Carbon nitrogen transfer can only occur sites free It be seen from that two are needed dissociation N2 but one site is sufficient decomposition CH4. From kinetics, adsorption isotherm 850 'C could derived. used as barrier against carbon or during heat treatment. sulphur-containing compounds annealing steel sheet N2-H2 atmospheres 650-700 will suppress decarburization denitrogenation. stops deposition CO Boudouard-type also formation graphite metastable cementite bulk. ethylene furnaces, additions to feedstock have proved advantageous protection high-alloy tubes carburization. This has been confirmed carburization, i.e. internal carbide formation, Incoloy 800 1000 carburizing CH4-H2-H2S atmospheres. By increasing 10-6, progressively minimum corrosive attack occurred H2S/H2= 10-4, while higher H2S contents simultaneous sulphidation observed. protective may important application petrochemistry, coal gasification high temperature nuclear reactor.