In this study, yttrium and aluminum were simultaneously co-deposited by diffusion into austenitic stainless steel (AISI 316L) substrates, by a single-step pack cementation process. Cyclic oxidation tests were conducted on the aluminide coating and on the yttrium modified aluminide coating of stainless steel in air under atmospheric pressure at temperatures 700 C° and 800 C° for 100h at 10h cyclic. Optical metallography and X-ray diffraction (XRD) techniques were used to characterize the changes in scale morphology and to identify the phases and oxidation products. The yttrium modified aluminde coating showed very good cyclic oxidation resistance compared to aluminide coating
In this study, silicon and yttrium were simultaneously co-deposited by diffusion into austenitic stainless steel (AISI 316L) substrates, by a single-step pack cementation process. Cyclic oxidation tests were conducted on the siliconized coating and on the yttrium doped siliconized coating of stainless steel in CO2 atmospheric pressure at temperatures 800° C and 900° C for 100h at 10h cyclic. The results show that the initial weight gain is rapid and increased as the temperature increased. The oxidation resistance of the yttrium doped siliconized of stainless steels was significantly improved as compared with the siliconized stainless steels. The scale formed on coated stainless steel after oxidation in CO2 environment was thick and consisted of Y2O3, SiO2, Fe2O3 and chromium oxide. Optical metallography (LOM) and X-ray diffraction (XRD) were used to characterize the resulting coating and cyclic oxidation structures.
In this study , Silicon and Aluminum with and without cerium were simultaneously co-deposited by diffusion into austenitic stainless steel (AISI 316L) substrates, by a single-step packcementation process. Cyclic hot corrosion tests were conducted on coated and uncoated austenitic stainless steel alloy with 50wt.% NaCl+50wt.%Na2So4 deposits at 750C° for 120h at 10h cycle. The results show that the hot corrosion resistance of both coated stainless steels, was significantly improved as compared with the uncoated steels. The scale formed on coated stainless steel after oxidation in mixture environment was consisted of NiAl2O4, NiFe2O4 and NiCr2O4. Optical metallography (LOM) and X-ray diffraction(XRD) was used to characterize the resulting coating and cyclic hot corrosion structures.