首页 | 本学科首页   官方微博 | 高级检索  
     


The influence of sulfur pressure on Sulfidation behaviour of NiCoCrAl(Y) alloys at high temperature
Authors:E Godlewska  E Roszczynialska  Z urek
Affiliation:E. Godlewska,E. Roszczynialska,Z. ?urek
Abstract:Sulfidation of alloy having nominal composition Ni-23Co-19Cr-12Al (wt%) with and without the addition of 0.6% yttrium was studied at temperatures 1073–1273 K in sulfur vapor at atmospheric pressure and in H2/H2S gas mixtures at sulfur pressure of 10?3 and 10?1.5 Pa. Sulfidation runs were followed thermogravimetrically. Phase and chemical composition of sulfide scales and scale morphologies were determined by means of XRD, EDX, EPM and SEM analyses. After certain initial period sulfidation of both materials followed approximately a parabolic rate law. The estimated sulfidation rates for each alloy increased with sulfur pressure and temperature. The sulfide scales on both materials showed complex microstructures and compositions, depending on sulfidation conditions, with several sulfide and sulfospinel phases present, such as (Ni,Co)S, (Ni,Co)3S4, (Ni,Co)Cr2S4, (Cr,Ni,Co)Al2S4 or (Cr,Ni,Co)S and (Cr,Ni,Co)3S4. There was no evidence of yttrium segregation either to the grain boundary regions in the scale or to the alloy/scale interface. Yttrium dissolved in the sulfide phases and accelerated the sulfidation process. This behaviour was ascribed to the doping effect.
Keywords:
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号