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P.k. Datta - One of the best experts on this subject based on the ideXlab platform.
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enhanced Sulphidation oxidation resistance of ti 45al 8nb alloy by multilayered coatings at 850 c for up to 675 h
Corrosion Engineering Science and Technology, 2014Co-Authors: T Dudziak, P.k. Datta, H L Du, A P Ehiasarian, Christina Reinhard, Eh P HovsepianAbstract:The high temperature Sulphidation/oxidation behaviour of three multilayered coatings CrAlYN/CrN etched by Y+, CrAlYN/CrN etched by Cr+ and CrAlYN/CrN etched CrAl+ and the uncoated γ-TiAl (Ti–45Al–8Nb (at-%) used as reference sample was studied at 850°C for 675 h. Sulphidation/oxidation test was performed in the environment of H2/H2S/H2O, yielding pS2 = 10−1 Pa and pO2 = 10−18 Pa. Kinetic data obtained by discontinuous gravimetric method showed that the multilayered coatings effectively enhanced the Sulphidation/oxidation resistance of γ-TiAl alloy. The corrosion resistance decreasing in order: CrAlYN/CrN etched by Y+>CrAlYN/CrN etched by CrAl+>CrAlYN/CrN etched by Cr+>γ-TiAl. Scale development studies using SEM, EDX and X-ray diffraction confirmed two regions of the coated materials: ‘affected,’ where coating cracked and developed non-protective TiO2 scale, and ‘unaffected,’ where protective (Al,Cr)2O3 scale formed. The uncoated γ-TiAl material, after exposure, showed a typical multilayered structure cons...
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enhanced Sulphidation oxidation resistance of ti 45al 8nb alloy by nanostructured cralyn crn coatings at 750 c
Materials and Corrosion-werkstoffe Und Korrosion, 2014Co-Authors: T Dudziak, P.k. Datta, H L Du, A P Ehiasarian, Christina Reinhard, Eh P HovsepianAbstract:This paper discusses the Sulphidation/oxidation protection offered by multilayer CrAlYN/CrN coatings etched by Cr, CrAl and Y ions, deposited by a combined high power impulse magnetron sputtering (HIPIMS)/unbalanced magnetron sputtering (UBM) technique on a Ti–45Al–8Nb alloy (at%). The test was performed at 7508C in an environment of H2/H2S/H2O yielding low oxygen (10 � 18 Pa) and high sulphur (10 � 1 Pa) partial pressures for up to 1000h. The results show that all the exposed materials underwent uneven degradation; some places developed a thin protective oxide scale (Al,Cr)2O3 with a tiny sulphur content, whilst others developed a porous non-protective TiO2 þAl2O3 scale as well with a tiny sulphur content.
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design and development of Sulphidation resistant coatings
Key Engineering Materials, 2008Co-Authors: H L Du, P.k. DattaAbstract:This paper discusses the design and development of Sulphidation resistant coatings. The first section discusses the rationale for designing and developing such coatings. The rationale for selecting the coating systems has been derived from our work on the HT Sulphidation behaviour of MCrAlYX (M=Co, or Co-Fe and X=V, Nb, Mo and W) type of coating alloys. This work has allowed the establishment of the mechanisms of Sulphidation and led to the choice of the coating systems discussed here. The second section describes the Sulphidation performance of several selected coatings, single and multilayer, deposited on Ti, TiAl and Ni-based alloys at 750-850oC in environments of low oxygen and high sulphur potentials.
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use of pvd deposited tin coating in retarding high temperature Sulphidation
Surface & Coatings Technology, 1996Co-Authors: H L Du, P.k. Datta, J S Burnellgray, A S James, A MatthewsAbstract:Abstract TiN coated Inconel 600 and Nimonic PE11 alloys were exposed to an atmosphere comprising a high sulphur potential (pS 2 ∼ 10 −1 Pa) and a low oxygen potential (pO 2 ∼ 10 −18 Pa) at 750 °C for periods up to 72 h. The Sulphidation kinetics, determined by a discontinuous gravimetric method, demonstrated that the TiN coating greatly enhanced the Sulphidation resistance of the substrates, particularly during the early stages of exposure. For TiN coated Inconel 600 the post-exposure analysis by scanning electron microscopy, energy-dispersive X-ray analysis, X-ray diffraction and glancing angle X-ray diffraction, showed the formation of an outer layer containing Ni 3 S 2 on the surface of the TiN coating while an inner layer consisting of Cr 2 S 3 developed at the coating/substrate interface. The double layered scale formed on uncoated Inconel 600 consisted of Ni 3 S 2 and Cr 2 S 3 . For the TiN coated Nimonic PE11, sulphide nodules consisting of three layers — (Fe,Ni) 9 S 8 (outmost) Cr 2 S 3 MoS 2 (innermost) were observed to develop and the TiN coating was sandwiched between (Fe,Ni) 9 S 8 and Cr 2 S 3 . The portion of the TiN coating which was enveloped by those sulphide nodules became unstable after long-term exposure and subsequently dissociated thereby causing the loss of environmental protection. Moreover, the coating was damaged mechanically by the growth of the sulphide nodules. The scale formed on the uncoated Nimonic PE11 showed the formation of a similar structure in a similar sequence.
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influence of plasma sprayed mo coating on Sulphidation behaviour of inconel 600 and nimonic pe11 alloys
Surface & Coatings Technology, 1995Co-Authors: H L Du, P.k. Datta, J S BurnellgrayAbstract:Abstract Sulphidation is a serious problem in many energy conversion systems. Sulphidation attack is particularly severe in environments of low oxygen ( p O2 ~10 −18 Pa) and high sulphur ( p S2 ~ 10 −1_10−3 Pa) potentials at temperatures above 700°C. Recognizing that refractory metals have a high resistance to Sulphidation in reducing environments, their use as overlay coatings in sulphur-containing environments deserves serious consideration. In the adoption of such an approach, Mo has been recognized as a highly Sulphidation-resistant metal with a Kp value of 10 −12 g 2 cm −4 s −1 in an atmosphere of p S2 ~ 10 −1 Pa at 750°C. In this study, Mo was deposited on two superalloys, Inconel 600 and Nimonic PE11, using air plasma spraying. The coated specimens were tested at 750°C for up to 168 h in an environment comprising p S2 ~ 10 −1 Pa and p O2 ~ 10 −18 Pa. The Sulphidation kinetics (this is not real through-layer kinetics, since the specimens had open edges) were determined by a discontinuous gravimetric method. The exposed samples were characterized and analysed using SEM, EDX and XRD techniques. For uncoated Inconel 600, a duplex scale was formed which consisted of an outer Ni 3 S 2 layer and an inner Cr 2 S 3 layer. The scale developed on uncoated Nimonic PE11 comprised three sub-scale layers—an outer (Fe, Ni) 9 S 8 layer, a mid Cr 2 S 3 layer and an inner MoS 2 layer. However, after prolonged exposure, the outer layer contained both (Fe, Ni) 9 S 8 and Ni 3 S 2 on the surface of the uncoated Nimonic PE11. The kinetics results demonstrated that Mo coating enhanced the corrosion resistance of both alloys, and particularly so for Nimonic PE11. For both substrates, Mo coating led to the development of two sub-scale layers at the early stages of exposure (e.g. up to 5 h). The outer layer consisted of Ni 3 S 2 for Inconel 600 and (Fe, Ni) 9 S 8 for Nimonic PE11. A MoS 2 layer constituted the inner layer for both materials. After prolonged Sulphidation, a Cr 2 S 3 layer gradually developed between the outer layer and the inner MoS 2 layer. It is apparent that the use of Mo coating hindered the formation of the Cr 2 S 3 layer.
H L Du - One of the best experts on this subject based on the ideXlab platform.
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enhanced Sulphidation oxidation resistance of ti 45al 8nb alloy by multilayered coatings at 850 c for up to 675 h
Corrosion Engineering Science and Technology, 2014Co-Authors: T Dudziak, P.k. Datta, H L Du, A P Ehiasarian, Christina Reinhard, Eh P HovsepianAbstract:The high temperature Sulphidation/oxidation behaviour of three multilayered coatings CrAlYN/CrN etched by Y+, CrAlYN/CrN etched by Cr+ and CrAlYN/CrN etched CrAl+ and the uncoated γ-TiAl (Ti–45Al–8Nb (at-%) used as reference sample was studied at 850°C for 675 h. Sulphidation/oxidation test was performed in the environment of H2/H2S/H2O, yielding pS2 = 10−1 Pa and pO2 = 10−18 Pa. Kinetic data obtained by discontinuous gravimetric method showed that the multilayered coatings effectively enhanced the Sulphidation/oxidation resistance of γ-TiAl alloy. The corrosion resistance decreasing in order: CrAlYN/CrN etched by Y+>CrAlYN/CrN etched by CrAl+>CrAlYN/CrN etched by Cr+>γ-TiAl. Scale development studies using SEM, EDX and X-ray diffraction confirmed two regions of the coated materials: ‘affected,’ where coating cracked and developed non-protective TiO2 scale, and ‘unaffected,’ where protective (Al,Cr)2O3 scale formed. The uncoated γ-TiAl material, after exposure, showed a typical multilayered structure cons...
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enhanced Sulphidation oxidation resistance of ti 45al 8nb alloy by nanostructured cralyn crn coatings at 750 c
Materials and Corrosion-werkstoffe Und Korrosion, 2014Co-Authors: T Dudziak, P.k. Datta, H L Du, A P Ehiasarian, Christina Reinhard, Eh P HovsepianAbstract:This paper discusses the Sulphidation/oxidation protection offered by multilayer CrAlYN/CrN coatings etched by Cr, CrAl and Y ions, deposited by a combined high power impulse magnetron sputtering (HIPIMS)/unbalanced magnetron sputtering (UBM) technique on a Ti–45Al–8Nb alloy (at%). The test was performed at 7508C in an environment of H2/H2S/H2O yielding low oxygen (10 � 18 Pa) and high sulphur (10 � 1 Pa) partial pressures for up to 1000h. The results show that all the exposed materials underwent uneven degradation; some places developed a thin protective oxide scale (Al,Cr)2O3 with a tiny sulphur content, whilst others developed a porous non-protective TiO2 þAl2O3 scale as well with a tiny sulphur content.
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design and development of Sulphidation resistant coatings
Key Engineering Materials, 2008Co-Authors: H L Du, P.k. DattaAbstract:This paper discusses the design and development of Sulphidation resistant coatings. The first section discusses the rationale for designing and developing such coatings. The rationale for selecting the coating systems has been derived from our work on the HT Sulphidation behaviour of MCrAlYX (M=Co, or Co-Fe and X=V, Nb, Mo and W) type of coating alloys. This work has allowed the establishment of the mechanisms of Sulphidation and led to the choice of the coating systems discussed here. The second section describes the Sulphidation performance of several selected coatings, single and multilayer, deposited on Ti, TiAl and Ni-based alloys at 750-850oC in environments of low oxygen and high sulphur potentials.
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use of pvd deposited tin coating in retarding high temperature Sulphidation
Surface & Coatings Technology, 1996Co-Authors: H L Du, P.k. Datta, J S Burnellgray, A S James, A MatthewsAbstract:Abstract TiN coated Inconel 600 and Nimonic PE11 alloys were exposed to an atmosphere comprising a high sulphur potential (pS 2 ∼ 10 −1 Pa) and a low oxygen potential (pO 2 ∼ 10 −18 Pa) at 750 °C for periods up to 72 h. The Sulphidation kinetics, determined by a discontinuous gravimetric method, demonstrated that the TiN coating greatly enhanced the Sulphidation resistance of the substrates, particularly during the early stages of exposure. For TiN coated Inconel 600 the post-exposure analysis by scanning electron microscopy, energy-dispersive X-ray analysis, X-ray diffraction and glancing angle X-ray diffraction, showed the formation of an outer layer containing Ni 3 S 2 on the surface of the TiN coating while an inner layer consisting of Cr 2 S 3 developed at the coating/substrate interface. The double layered scale formed on uncoated Inconel 600 consisted of Ni 3 S 2 and Cr 2 S 3 . For the TiN coated Nimonic PE11, sulphide nodules consisting of three layers — (Fe,Ni) 9 S 8 (outmost) Cr 2 S 3 MoS 2 (innermost) were observed to develop and the TiN coating was sandwiched between (Fe,Ni) 9 S 8 and Cr 2 S 3 . The portion of the TiN coating which was enveloped by those sulphide nodules became unstable after long-term exposure and subsequently dissociated thereby causing the loss of environmental protection. Moreover, the coating was damaged mechanically by the growth of the sulphide nodules. The scale formed on the uncoated Nimonic PE11 showed the formation of a similar structure in a similar sequence.
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influence of plasma sprayed mo coating on Sulphidation behaviour of inconel 600 and nimonic pe11 alloys
Surface & Coatings Technology, 1995Co-Authors: H L Du, P.k. Datta, J S BurnellgrayAbstract:Abstract Sulphidation is a serious problem in many energy conversion systems. Sulphidation attack is particularly severe in environments of low oxygen ( p O2 ~10 −18 Pa) and high sulphur ( p S2 ~ 10 −1_10−3 Pa) potentials at temperatures above 700°C. Recognizing that refractory metals have a high resistance to Sulphidation in reducing environments, their use as overlay coatings in sulphur-containing environments deserves serious consideration. In the adoption of such an approach, Mo has been recognized as a highly Sulphidation-resistant metal with a Kp value of 10 −12 g 2 cm −4 s −1 in an atmosphere of p S2 ~ 10 −1 Pa at 750°C. In this study, Mo was deposited on two superalloys, Inconel 600 and Nimonic PE11, using air plasma spraying. The coated specimens were tested at 750°C for up to 168 h in an environment comprising p S2 ~ 10 −1 Pa and p O2 ~ 10 −18 Pa. The Sulphidation kinetics (this is not real through-layer kinetics, since the specimens had open edges) were determined by a discontinuous gravimetric method. The exposed samples were characterized and analysed using SEM, EDX and XRD techniques. For uncoated Inconel 600, a duplex scale was formed which consisted of an outer Ni 3 S 2 layer and an inner Cr 2 S 3 layer. The scale developed on uncoated Nimonic PE11 comprised three sub-scale layers—an outer (Fe, Ni) 9 S 8 layer, a mid Cr 2 S 3 layer and an inner MoS 2 layer. However, after prolonged exposure, the outer layer contained both (Fe, Ni) 9 S 8 and Ni 3 S 2 on the surface of the uncoated Nimonic PE11. The kinetics results demonstrated that Mo coating enhanced the corrosion resistance of both alloys, and particularly so for Nimonic PE11. For both substrates, Mo coating led to the development of two sub-scale layers at the early stages of exposure (e.g. up to 5 h). The outer layer consisted of Ni 3 S 2 for Inconel 600 and (Fe, Ni) 9 S 8 for Nimonic PE11. A MoS 2 layer constituted the inner layer for both materials. After prolonged Sulphidation, a Cr 2 S 3 layer gradually developed between the outer layer and the inner MoS 2 layer. It is apparent that the use of Mo coating hindered the formation of the Cr 2 S 3 layer.
S Mrowec - One of the best experts on this subject based on the ideXlab platform.
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on the Sulphidation mechanism of niobium and some of nb alloys at high temperatures
Corrosion Science, 2008Co-Authors: Z Grzesik, S MrowecAbstract:Abstract The kinetics and mechanism of niobium Sulphidation have been studied as a function of temperature (700–1000 °C) and sulphur pressure (10−4–104 Pa) in pure sulphur vapour and H2–H2S gas mixtures, using microthermogravimetric technique. It has been found that in both different sulphidizing atmospheres the Sulphidation process follows parabolic kinetics, being thus diffusion controlled. Marker experiments have shown that the slowest step of the overall reaction rate is the outward diffusion of cations. No influence of small amounts of impurities on the Sulphidation rate has been observed in this study. Excellent agreement between calculated and experimentally determined parabolic rate constants has been obtained under the assumption, that the correct formula of the sulphide scale on niobium is Nb2±yS3 and not Nb1+xS2, as suggested by Gesmundo. It has been found that the rate of niobium Sulphidation in H2–H2S gas mixtures is much higher than in pure sulphur vapour, strongly suggesting that the dissolution of hydrogen in the growing scale influences the defect structure in this sulphide.
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the influence of lithium on the kinetics and mechanism of manganese Sulphidation
Corrosion Science, 2006Co-Authors: Zbigniew Grzesik, S MrowecAbstract:Abstract The influence of monovalent impurity (lithium) on the kinetics of manganese Sulphidation has been studied as a function of temperature (800–1000 °C) and sulphur pressure (1–10 4 Pa) using microthermogravimetric technique. It has been found that the incorporation of lithium atoms into the growing sulphide scale on manganese decreases the rate of the reaction of about two orders of magnitude. These results are in quantitative agreement with theoretical predictions following from the Hauffe–Wagner theory of alloy oxidation.
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Sulphidation of cobalt at high temperatures
Journal of Materials Science, 1998Co-Authors: S Mrowec, Marek Danielewski, A WojtowiczAbstract:The kinetics and mechanism of cobalt Sulphidation have been studied as a function of temperature (773–1023 K) and sulphur partial pressure (1–104 Pa) by means of thermogravimetric, SEM and X-ray techniques, and also using inert-marker and ratio-tracer methods. It has been shown that the Sulphidation process is diffusion controlled, the rate-determining step being the outward volume diffusion of cations. According to the phase diagram of the Co–S system, the sulphide scale on cobalt is heterogeneous. At sulphur pressures higher than the dissociation pressure of the CoS2 phase, the Sulphidation rate is pressure independent, and at lower pressures it increases with rising pressure, in agreement with theoretical predictions. The apparent activation energy of Sulphidation is considerably higher for multilayer than for double-layer scale formation, because the main part of multilayer scale is growing at the dissociation pressure of the CoS2 phase, which increases with increasing temperature. Over the whole temperature and pressure range studied, the rate of cobalt Sulphidation is more than three orders of magnitude higher than the oxidation rate of this metal. Rapid degradation of cobalt in a sulphur atmosphere results mainly from a very high defect concentration in Co1-yS and Co9S8 sulphides, participating in comparable amounts in the scale formation on this metal at T>900 K. The only sulphide of cobalt in which the defect concentration may be very low is CoS2, the growth rate of this sulphide layer being more than two orders of magnitude lower than that of other cobalt sulphides. © 1998 Chapman & Hall
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an rbs study of the Sulphidation behaviour of niobium and nbal alloys
Corrosion Science, 1995Co-Authors: Z Grzesik, K Hashimoto, K Takahiro, S Yamaguchi, S MrowecAbstract:Abstract The growth mechanisms of the sulphide scales on niobium and niobium-aluminium alloys at a temperature of 1073 K and sulphur pressure of 1 kPa have been studied by means of Rutherford backscattering (RBS) with the aid of a marker technique. A gold marker film of about 1 nm thickness was deposited on the surface of niobium as well as on Nb-0.6 at% Al, Nb-15.2 at% Al and Nb-63.4 at% Al alloys by vacuum evaporation. After Sulphidation the gold marker distribution in the scale has been determined by RBS. It has been found that Sulphidation of niobium occurs by the outward diffusion of niobium cations since the gold marker has been located at the metal/scale interface. The scale structure for the Nb-0.6Al alloy is almost the same as that for niobium because the alloy aluminium content is too low to form a separate phase of aluminium sulphide. Other niobium-aluminium alloys form a double layer scale with an outer aluminium sulphide layer and an inner niobium sulphide layer, both of which are formed by the outward diffusion of cations.
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the Sulphidation behavior of moal alloys with low aluminum contents
Corrosion Science, 1994Co-Authors: Z Grzesik, H Habazaki, K Hashimoto, S MrowecAbstract:Abstract The beneficial effect of alloying with aluminum to enhance the Sulphidation resistance of molybdenum using sputter-deposited amorphous Mo-Al alloys has been studied as a function of temperature (1073–1273 K), aluminum content (1.7, 6.2 and 10.7 at% Al) and sulphur vapor pressure (20–4000 Pa) in He-S 2 gas mixtures. It has been shown that the Sulphidation process follows parabolic kinetics, being diffusion controlled. The reaction rate of Mo-Al alloys with low aluminum contents is lower than that of pure molybdenum and decreases with increasing aluminum content in the alloy. Because sulphide scales formed on Mo-Al alloys containing small amounts of aluminum are homogeneous and composed only of MoS 2 , the lower Sulphidation rate of those alloys is explained in terms of the aluminum doping effect in the MoS 2 scale. It is believed that the better protective properties of the sulphide scale on Mo-Al alloys in comparison with those of the MoS 2 scale on pure molybdenum result from a lower defect concentration in aluminum-doped MoS 2 phase. The experimentally obtained dependence of the Sulphidation rate of Mo-1.7Al alloy on the sulphur pressure at 1173 K is in accordance with that predicted from theoretical considerations.
S M Dubiel - One of the best experts on this subject based on the ideXlab platform.
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effect of tin on high temperature Sulphidation of fe cr alloys in h2 h2s atmospheres
Corrosion Science, 2006Co-Authors: S środa, Z żurek, S M DubielAbstract:Abstract The high temperature Sulphidation behaviour of Fe–46Cr–xSn (x = 0; 0.2; 0.5; 1; 2) alloys has been studied at temperatures of 1073, 1173 and 1273 K in H2/H2S mixtures with different sulphur vapour partial pressures of 10−1, 10−3 and 10−5 Pa. Thermogravimetric studies in combination with scanning electron microscope (SEM), with energy dispersive spectrometer (EDS), and X-ray diffraction (XRD) techniques, have displayed a significant influence of the sulphur partial pressure on the composition and growth rate of the sulphide scale. The results have shown that addition of tin increases the Sulphidation rate of Fe–46Cr alloys but not considerably (except at temperatures of 1073 and 1173 K combined with sulphur partial pressure of 10−5 Pa). The metallic core of the studied samples was enriched in tin and iron, moreover tin was found in the internal layer close to the metallic core as metallic FexSny inclusions with tin concentrations of up to 12 at.%.
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a study of high temperature Sulphidation products of pure and sn doped fe cr alloys
Journal of Alloys and Compounds, 2002Co-Authors: J Cieślak, S M Dubiel, S środa, Z żurekAbstract:Abstract Sulphidation products, i.e. scales and metallic cores resulting from high-temperature Sulphidation carried out in an atmosphere of H 2 /H 2 S mixture on pure and Sn-doped quasi-equiatomic Fe–Cr alloys in α and σ phases were investigated with scanning electron microscopy, X-ray diffraction and Mossbauer spectroscopy. The scales were found to have a two-layer structure; the outer and the inner scale. Iron was found to exist in various forms within the scales; magnetic and non-magnetic (Fe,Cr) 1− x S (the latter obviously due to fine-grains), α-Fe (mostly within the inner scales) and (Fe,Cr)S 1+ x (only in case of Sn-doped σ-phase alloys). Metallic cores were found to have Fe- and Sn-enriched outer mantel whose thickness was determined to be ∼45 μm and grain-like inner core with Cr-enrichment in form of CrS within the grain-borders.
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investigation of scales resulted from a high temperature Sulphidation of fe cr alloys
Journal of Alloys and Compounds, 1998Co-Authors: J Cieślak, S M Dubiel, Z żurekAbstract:Abstract Scales resulted from a Sulphidation of a series of Fe 100− x Cr x alloys ( x ≤45) at T =1073 K in an atmosphere of H 2 S/H 2 with the partial pressure of sulphur p S 2 =10 −3 Pa were investigated by means of Mossbauer spectroscopy, X-ray diffraction, electron- and light-microscopy as well as electron-probe microanalysis (EPMA). The results obtained gave evidence that morphologically all the scales, excepting the one grown on the most concentrated alloy, were macroscopically homogenous (single-layer). The exceptional scale had a two-layer structure. Crystallographically, all the scales were single-phase and had a structure of the FeS except the one grown on Fe 90 Cr 10 alloy which was, in addition, composed of Fe 7 S 8 . The structure of the duplex scale was not determined. Mossbauer spectra recorded both in a transmission geometry as well as in a CEMS mode gave clear evidence that the single-layer scales were microscopically not uniform. The spectra characteristic of the scales grown on the alloys with x ≤10 consisted of two subspectra: one had spectral parameters similar to those of F 1+ δ S, while the other subspectrum had a broad distribution of the hyperfine field. Based on the X-ray diffractograms and EPMA-profiles the latter could have been identified as originated from the (Fe,Cr) 1− δ . The relative amount of (Fe,Cr) 1− δ S was found to increase with x , and for x ≥15 the entire scale was composed of it. A relationship between the kinetics of Sulphidation, which was determined from the weight gain of test pieces, the morphology and the structure of the scales formed is discussed, too.
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further support for the inversion in the selective Sulphidation of fecr alloys
Solid State Communications, 1998Co-Authors: J Cieślak, S M DubielAbstract:Abstract Scales resulted from Sulphidation of Fe 100− x Cr x alloys ( x ≤ 26) at T =1073 K in an atmosphere of H 2 S H 2 with a partial pressure of sulphur equal to 10 −3 Pa were investigated by means of X-ray diffraction, electron microprobe analysis, electron microscopy and Mossbauer spectroscopy (both transmission and CEMS mode). The spectral parameters gave a clear evidence in favour of our previous conclusion that an inversion of the Sulphidation preference occurs at x cr = 3 [ J. Alloys Comp. , 198 , 1993, L11].
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Sulphidation induced changes in the metallic phase of fe cr alloys
Hyperfine Interactions, 1994Co-Authors: J Cieślak, S M Dubiel, Z żurekAbstract:The influence of Sulphidation on the metallic phase in a series of Fe100−xCr x alloys (x 5.0 at.%, in iron.
Z żurek - One of the best experts on this subject based on the ideXlab platform.
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effect of tin on high temperature Sulphidation of fe cr alloys in h2 h2s atmospheres
Corrosion Science, 2006Co-Authors: S środa, Z żurek, S M DubielAbstract:Abstract The high temperature Sulphidation behaviour of Fe–46Cr–xSn (x = 0; 0.2; 0.5; 1; 2) alloys has been studied at temperatures of 1073, 1173 and 1273 K in H2/H2S mixtures with different sulphur vapour partial pressures of 10−1, 10−3 and 10−5 Pa. Thermogravimetric studies in combination with scanning electron microscope (SEM), with energy dispersive spectrometer (EDS), and X-ray diffraction (XRD) techniques, have displayed a significant influence of the sulphur partial pressure on the composition and growth rate of the sulphide scale. The results have shown that addition of tin increases the Sulphidation rate of Fe–46Cr alloys but not considerably (except at temperatures of 1073 and 1173 K combined with sulphur partial pressure of 10−5 Pa). The metallic core of the studied samples was enriched in tin and iron, moreover tin was found in the internal layer close to the metallic core as metallic FexSny inclusions with tin concentrations of up to 12 at.%.
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a study of high temperature Sulphidation products of pure and sn doped fe cr alloys
Journal of Alloys and Compounds, 2002Co-Authors: J Cieślak, S M Dubiel, S środa, Z żurekAbstract:Abstract Sulphidation products, i.e. scales and metallic cores resulting from high-temperature Sulphidation carried out in an atmosphere of H 2 /H 2 S mixture on pure and Sn-doped quasi-equiatomic Fe–Cr alloys in α and σ phases were investigated with scanning electron microscopy, X-ray diffraction and Mossbauer spectroscopy. The scales were found to have a two-layer structure; the outer and the inner scale. Iron was found to exist in various forms within the scales; magnetic and non-magnetic (Fe,Cr) 1− x S (the latter obviously due to fine-grains), α-Fe (mostly within the inner scales) and (Fe,Cr)S 1+ x (only in case of Sn-doped σ-phase alloys). Metallic cores were found to have Fe- and Sn-enriched outer mantel whose thickness was determined to be ∼45 μm and grain-like inner core with Cr-enrichment in form of CrS within the grain-borders.
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investigation of scales resulted from a high temperature Sulphidation of fe cr alloys
Journal of Alloys and Compounds, 1998Co-Authors: J Cieślak, S M Dubiel, Z żurekAbstract:Abstract Scales resulted from a Sulphidation of a series of Fe 100− x Cr x alloys ( x ≤45) at T =1073 K in an atmosphere of H 2 S/H 2 with the partial pressure of sulphur p S 2 =10 −3 Pa were investigated by means of Mossbauer spectroscopy, X-ray diffraction, electron- and light-microscopy as well as electron-probe microanalysis (EPMA). The results obtained gave evidence that morphologically all the scales, excepting the one grown on the most concentrated alloy, were macroscopically homogenous (single-layer). The exceptional scale had a two-layer structure. Crystallographically, all the scales were single-phase and had a structure of the FeS except the one grown on Fe 90 Cr 10 alloy which was, in addition, composed of Fe 7 S 8 . The structure of the duplex scale was not determined. Mossbauer spectra recorded both in a transmission geometry as well as in a CEMS mode gave clear evidence that the single-layer scales were microscopically not uniform. The spectra characteristic of the scales grown on the alloys with x ≤10 consisted of two subspectra: one had spectral parameters similar to those of F 1+ δ S, while the other subspectrum had a broad distribution of the hyperfine field. Based on the X-ray diffractograms and EPMA-profiles the latter could have been identified as originated from the (Fe,Cr) 1− δ . The relative amount of (Fe,Cr) 1− δ S was found to increase with x , and for x ≥15 the entire scale was composed of it. A relationship between the kinetics of Sulphidation, which was determined from the weight gain of test pieces, the morphology and the structure of the scales formed is discussed, too.
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Sulphidation induced changes in the metallic phase of fe cr alloys
Hyperfine Interactions, 1994Co-Authors: J Cieślak, S M Dubiel, Z żurekAbstract:The influence of Sulphidation on the metallic phase in a series of Fe100−xCr x alloys (x 5.0 at.%, in iron.
