David Young

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• Doctor of Philosophy
• Professor (Full) at UNSW Sydney

Alloys of Ni–25Cr–(2Mn–1Si) under mixed deposits of ash + (0, 10, 50 and 90) wt% sulphate were exposed to an Ar–60CO2–20H2O gas at 650 and 750 °C for up to 300 h, forming both protective chromia and regions of Ni-rich oxide. The presence of ash + sulphate mixtures improved Ni–25Cr alloy protection, increasing surface coverage by thin, protective ch...

Model alloy, Fe-20Cr (wt%), was oxidized in two gas mixtures Ar-5H2O-(5H2) (vol%) at 850 °C. The alloy formed Cr2O3 scales in both gases. The Cr2O3 scale developed faster in Ar-5H2O-5H2 and contained fine pores, whilst that grown in Ar-5H2O was dense. Experiments with inert SiO2 marker revealed that the Cr2O3 scale growth in Ar-5H2O-(5H2) was contr...

Model alloy, Fe-20Cr (wt.%), was oxidized in two gas mixtures Ar-5H 2 O-(5H 2 ) (vol.%) at 850 o C. The alloy formed Cr 2 O 3 scales in both gases. The Cr 2 O 3 scale developed faster in Ar-5H 2 O-5H 2 and contained fine pores, whilst that grown in Ar-5H 2 O was dense. Experiments with inert SiO 2 marker revealed that the Cr 2 O 3 scale growth in A...

Model alloys, Fe–20Cr and Fe–20Cr–20Ni (wt%) with and without 1% Si, were exposed to four different gas mixtures Ar–10H2O, Ar–10H2O–0.1HCl, Ar–10H2O–0.1HCl–10CO2, Ar–10H2O–0.1HCl–10CO2–0.5SO2 (vol.%) at 650 °C. The Fe–20Cr and Fe–20Cr–20Ni alloys underwent breakaway corrosion in Ar–10H2O–(0.1HCl)–(10CO2), forming Cr2O3 and Fe-rich oxide nodules. Si...

Corrosion behaviours of Fe–25Cr, Fe–25Cr–2Mn–1Si, Fe–25Cr–20Ni, 310SS, Ni–25Cr, and Ni–25Cr–2Mn–1Si (all in wt%) with and without NaCl–KCl deposits in Ar–60%CO2–20%H2O gas at 750 °C were studied. Without salt deposits, Fe–25Cr performed protectively, while Fe–25Cr–20Ni and Ni–25Cr underwent breakaway oxidation with multilayered scales formed. Addin...

The initial stages of oxidation of 9Cr steel in CO2, O2, CO2–O2 and CO2–O2–H2O is studied by gas phase analysis (GPA) at 550 °C using ¹³C16,16O2, 18,18O2 and ²H2¹⁶O isotopic molecules in order to discriminate the reactions of all gas molecules. Protective and non-protective oxide scales are formed on 9Cr steel depending on the exact composition of...

The initial stages of oxidation of 9Cr steel in CO 2 , O 2 , CO 2 -O 2 and CO 2 -O 2 -H 2 O is studied by Gas Phase Analysis (GPA) at 550°C using ¹³ C 16,16 O 2 , 18,18 O 2 and ² H 2 ¹⁶ O isotopic molecules in order to discriminate the reactions of all gas molecules. Protective and non-protective oxide scales are formed on 9Cr steel depending on th...

To provide clarity on the poorly-understood mechanism of breakaway oxidation, corrosion of Fe9Cr1Mo steel in pressurised CO2 is quantified and modelled. The temperature range 400 - 600 oC, relevant to nuclear power plants, is emphasised. Attack is in the form of combined oxide scale growth and internal carburisation of the metal. Carbon activity in...

Corrosion behaviours of Fe-25Cr, Fe-25Cr-2Mn-1Si, Fe-25Cr-20Ni, 310SS, Ni-25Cr, and Ni-25Cr-2Mn-1Si (all in wt. %) with and without NaCl-KCl deposits in Ar-60%CO 2 -20%H 2 O gas at 750 o C were studied. Without salt deposits, Fe-25Cr performed protectively, while Fe-25Cr-20Ni and Ni-25Cr underwent breakaway oxidation with multi-layered scales forme...

Silicon-bearing vapour at low pressure was used to deposit SiO2 during exposure of pure chromium, Fe-30Cr (wt.%) and Kanthal APM alloy to an Ar-10H2O-0.1HCl mixture (vol.%) at 650 °C. Pure Cr formed porous chromia blades on top of a polycrystalline Cr2O3 scale containing SiO2. A model Fe-30Cr alloy formed a scale consisting of a thick, amorphous (C...

High temperature corrosion by chlorides and siloxanes, common impurities in waste incinerators, was investigated. A model alloy Fe-30Cr (wt.%) exposed to Ar-10H2O and Ar-10H2O-0.1HCl mixtures (vol.%) at 650 oC formed protective Cr2O3 scales. Contaminating the reaction gases by siloxanes resulted in an amorphous (Cr,Si)Ox scale layer in Ar-10H2O-0.1...

The corrosion behaviour of Fe-25Cr-20Ni, 310SS, Ni-25Cr, and Ni-25Cr-2Mn-1Si (all in wt. %) with and without NaCl-KCl deposits in Ar-60%CO2-20%H2O gas at 650 oC was investigated. Without salt deposits, both Fe-25Cr-20Ni and Ni-25Cr formed thick internal oxidation zones (IOZs) and external oxide scales. The addition of Si+Mn significantly improved t...

Austenitic Fe-13.50Mn-3.98Si-9.54Cr-4.51Ni shape memory alloyed with (0.18, 0.42 and 0.96 wt.%) Ce was exposed in air at 800 °C. Both 0.18 and 0.42 wt.% Cerium additions yielded protective kinetics, while the 0.96 wt.% Ce content did not change the oxidation resistance. Increased oxidation resistance was related to the growth of a fine-grained oxid...

Oxy-fuel combustion is one of promising technologies, facilitating CO2 capture and storage. However, the increased temperature and the increased levels of both deposits and CO2 gas challenge the current boiler and superheater alloys, usually Fe-Cr steels [1, 2]. Iron-based alloys could undergo fireside hot corrosion if sulphates are deposited on th...

Two MCrAlY coatings with the same nominal composition but different microstructures are prepared by magnetron sputtering (MS) and arc ion plating (AIP). Their oxidation at 1000°C led to very different results. The relatively coarse grained AIP coating formed a duplex-layer scale, consisting of external θ-Al2O3 and internal α-Al2O3, with small amoun...

A model Si-free alloy, Fe-30Cr (wt.%), was exposed to Ar-10H 2 O mixture (in vol.%) at 650 °C, forming a protective Cr 2 O 3 scale, which contained silica. Liquid water used to form water vapour in a bubbler was either deionised or distilled. In both cases, low-level water impurities of Si, F, Cl, S, and Ca matched those detected in the Cr 2 O 3 sc...

Corrosion behaviour of Fe–Cr (15, 20, 25, or 30 wt.%) alloys in wet CO2 without and with HCl (0.05 or 0.1 vol%) at 750 °C was investigated. The results are compared with those at 650 °C to reveal the temperature effect. In general, weight gain kinetics and oxide scaling rates decreased with the increased chromium levels. The effect of temperature o...

A model ferritic Fe-25 wt. % Cr alloy exposed to an Ar-60CO2-20H2O gas mixture at 650 oC experienced rapid oxide scale growth and simultaneous internal carburization. When a deposit of NaCl-KCl was present on the alloy surface, it developed a more porous oxide scale and more extensive carburization. In the absence of salt, alloy additions of Si+Mn...

Exposure of Ni–Cr alloys containing 5–30 wt% Cr to Ar-20O2 and Ar-20O2-20H2O at 650 °C produced an external NiO layer, internal chromium oxidation and an intermediate zone of NiO + Cr2O3. The NiO layer growth rate decreased with increasing alloy Cr content. Addition of water vapor to dry O2 changed the NiO grain structure from equiaxed-shaped to co...

The corrosion behavior of seven commercial alloys (602CA, 310SS, 253MA, 800H, F321, F316L, 304SS) was investigated in a wet CO2 gas under cyclic reactions up to 150 cycles at 650°C. Water vapor accelerated the oxidation of all alloys. Alloy 602CA was alumina-forming in dry CO2 but changed to chromia-forming in the wet gas. In wet gas, the 310SS and...

Heat-resisting alloys are designed to survive high-temperature oxidation by forming a slow-growing scale, usually Cr 2 O 3 , which acts as a barrier between the metal and its environment. However, alloys that succeed in this way when exposed to hot oxygen or air fail to do so in CO 2 gas. Instead, they exhibit rapid “breakaway” corrosion, developin...

The corrosion behaviour of several model and commercial Fe-based alloys, all with 25 wt% Cr, in CO2–H2O gases at 750 °C with and without sulphate deposits was studied. In the absence of sulphate deposits, ferritic alloys Fe–25Cr and Fe–25Cr–2Mn–1Si outperformed austenitic alloys Fe–25Cr–20Ni and 310 stainless steel. This pattern of behaviour is exp...

Corrosion of iron and mild steel in gas environments at 550 °C was studied by Gas Phase Analysis (GPA) using 13C16,16O2 and 18,18O2. This technique is shown to be very powerful in identifying gas–metal and gas-gas interactions. Mild steel reacts with O2 to oxidize and decarburise, with CO2 to decarburise but not oxidize, and with CO2/O2 to oxidize...

The corrosion performance of several model and commercial Ni-base alloys, with 20 − 25 wt % Cr, in CO2-H2O gases at 750 °C with and without sulphate deposits was examined. In the absence of sulphate deposits, commercial NiCoCrAl alloy and Alloy 625 formed chromia-rich scales, but model alloys Ni-25Cr and Ni-25Cr-2Mn-1Si did not. Wagner’s theory was...

Oxide scales formed on chromium-silicon model alloys at 1200 °C in synthetic air were characterized using electron microscopy and diffraction methods. Additions of Si to chromium led to SiO2 growth underneath the chromia scale. The chromia scale was mostly fine-grained, but also contained numerous abnormally large single crystals growing out of the...

The effect of silicon on the corrosion of Fe-20Cr and Fe-20Cr-20Ni was investigated in N2-10CO2-10H2O-(0.05 and 0.1 vol.% HCl) gas at 650°C. Breakaway oxidation occurred for undoped alloys in all gases. The addition of Si (0.5%) suppressed breakaway oxidation of both alloys in all gases by forming a thin protective oxide scale. In HCl-free gases, b...

The oxidation behaviour of model alloys Ni-(20, 30)Cr (wt.%) with (0, 1, 5, 15%) Fe was investigated at 800 °C in Ar-20%CO2-20%H2O gas. All 20Cr alloys developed a multilayered scale, and the outer scale layers on alloys containing iron were subject to spallation. However, all 30Cr alloys developed a scale which was predominantly chromia scale and...

Chlorine-induced high-temperature corrosion is a major problem for structural materials used in incinerators because of the release of hydrochloride during waste combustion. In this work, the effect of HCl additions (0.05 and 0.1 vol%) to a N2–10CO2–10H2O gas on the oxidation of binary ferritic Fe—(15, 20, 25 and 30 wt%) Cr alloys was investigated...

Numerical modelling of the degradation of P92 and VM12 martensitic stainless steels in gaseous (i) 70%CO2-30%H2O and (ii) Ar-50%CO2 at 550°C is reported, emphasising the formation of duplex oxide scale and internal carburisation. A 1D numerical model is presented for the evolution of multiphase regions, subject to a Robin-type boundary condition re...

Model alloys Ni-(20, 30)Cr (wt %) alloyed with (0, 1, 5, 15 %) Fe were exposed to flowing Ar-20 %CO2 gas at 800 °C. Samples were electropolished before reaction to avoid surface cold work effects on alloys diffusion. The oxidation resistance of 20Cr alloys gradually increased with increasing alloy Fe levels. All 30Cr alloys formed external chromia...

Model alloys Ni-(20, 30)Cr with 1 Si, 1.5 Al or 2 Ti (all in wt.%) were exposed to Ar-20CO2-20H2O (in vol%) at 700 °C. Alloy specimens were electropolished before reaction to avoid cold working effects on alloy diffusion. The Ni-(20, 30)Cr alloys formed a NiO scale and an internal oxidation zone, together with NiO rods on the sample surface. The ox...

Model alloys of Fe-20Cr and Ni-20Cr (all compositions in weight %) and variants containing small amounts of Si or Mn were exposed to Ar-20CO2 and Ar-20CO2-H2O (volume %) at 650 or 700°C. Protective Cr2O3 scale was more readily formed on Fe-20Cr than Ni-20Cr, as a result of the different alloy diffusion coefficients. Silicon additions slowed chromia...

An electroplated interlayer of Ni-Re was prepared as a diffusion barrier to inhibit interdiffusion between Ni-Al coating and an iron alloy substrate. The oxidation behavior of the Ni-Al coating with and without the diffusion barrier was studied at 650 °C in dry CO2 gas for up to 660 h. The Ni-Al coating without a diffusion barrier underwent severe...

Model alloys Ni-(20, 30)Cr (wt%) with (0, 1, 5, 15%) Fe were reacted with Ar-20CO 2 -20H 2 O gas at 650 and 700 °C. Samples were electropolished to avoid sub-surface cold work effects on alloy diffusion. All 20Cr alloys developed non-protective scales. However, Fe alloying enhanced the corrosion resistance of Ni-30Cr by promoting the formation of a...

Grade 316L stainless steel was exposed to liquid tellurium at 551°C. Corrosion was rapid, leading to more than 100 μ m loss of steel section in 30 min. The corrosion product was a mixed telluride scale, which thickened according to parabolic kinetics whilst simultaneously dissolving at its outer surface into the liquid tellurium. A mathematical mod...

The corrosion behaviour of binary Ni-Cr alloys with 5–30 wt% Cr was studied in Ar-20CO2-20H2O at 700 and 800 °C. Samples were electropolished before exposure to avoid the effect of surface cold work on alloy diffusion. At 700 °C, all alloys underwent both outer NiO formation and internal oxidation. At 800 °C, the alloys containing 5–20 wt% Cr devel...

Model alloys of Fe–9Cr, Fe–20Cr and their ternaries containing 2Mn or 0.5Si (wt%) were exposed to Ar–20%CO2 and Ar–20%CO2–0.5%SO2 at 650 °C, and the results were compared with those in wet CO2, with and without SO2. In S-free, dry CO2, all 9Cr alloys went into breakaway, and the 20Cr alloys formed regions of protective Cr2O3, but also fast-growing...

Commercial alloys 282, 230, HR160, HR120 and 188 were exposed to supercritical CO2 and to air at temperatures of 700–1000 °C. Alloy specimens took the form of thick-walled tubes, which were pressurised internally with flowing CO2 to simulate the likely stress conditions in service. All alloys formed protective scales containing continuous chromia l...

Supercritical CO2 has been suggested as a candidate heat transfer fluid in concentrated solar power plants, but its implementation requires cost-effective materials that can resist corrosion in high-temperature C-rich environments. Alumina-forming alloys are known to resist high-temperature corrosion in oxygen, but little is known about their perfo...

During oxyfuel combustion metallic heat exchangers are subjected to service environments which substantially differ from those prevailing during the conventional air firing process. In the present study the behaviour of three selected construction materials (P92, super S304HCu and alloy 617) during exposure in simulated oxyfuel gas with and without...

High-temperature corrosion of heat-resisting alloys by CO2 produces external oxide scales and, in many cases, simultaneous internal carburization. In general, higher alloy chromium levels are required to achieve protective chromia formation in CO2 compared with in air. Corrosion reaction mechanisms are examined, particularly the thermodynamics whic...

Hot CO 2 gas is surprisingly corrosive to chromia forming alloys as a result of internal carburisation, which decreases the ability of an alloy to form a protective Cr-rich oxide scale. Comparison of Fe- and Ni- base alloys reacted with Ar-20CO 2 shows that the latter can provide superior performance, by virtue of their better resistance to carburi...

Binary Ni-Cr alloys containing 5–30 wt% Cr were oxidized in Ar-20CO2-20H2O gas at 650 °C. Weight gain kinetics for alloys reacted with electropolished surfaces generally increased with increasing Cr content up to 25 wt%. All alloys underwent both internal oxidation and outer NiO formation. The NiO developed as separated, isolated growths on all all...

A model alloy Fe-20Cr-0.5Si (wt.%) exposed to Ar-20CO2 and Ar-20CO2-20H2O at 818 °C formed a duplex scale of an outer Cr2O3 layer and an inner SiO2 layer in both gases. Water vapour promoted formation of fine Cr2O3 grains and additional Cr2O3 blades. The blades were discovered by high resolution electron microscopy to be bicrystals, containing an i...

Model alloys Fe-20Cr and Fe-20Cr-0.5Si (wt.%) were exposed to Ar-20CO2 and Ar-20CO2-20H2O gas mixtures at 650 and 818 °C, forming Cr2O3 scales. Impurities segregated to chromia grain boundaries: carbon at sub-monolayer level, iron as spinel in narrow (10–20 nm) bands alongside the boundaries and silicon as dispersed glassy SiO2 nanoparticles. Therm...

Model alloys Ni-(20, 30)Cr (wt.%) with (0.1, 1)% Si, 1.5% Al or (1, 2)% Ti were exposed to Ar-20CO2 at 700°C. Samples were electropolished before reaction to avoid cold working effects on alloy diffusion. The Ni-20Cr alloy formed a thick NiO scale and an internal oxidation zone, whereas Ni-30Cr formed a duplex scale of NiO and Cr2O3 layers. The Si...

Model alloys Fe–20Cr–0.5Si and Fe–20Cr–2Mn (wt-%) were exposed to Ar–20CO2 and Ar–20CO2–20H2O at either 818 or 650°C. In dry gas, protective scales on Fe–20Cr–0.5Si consisted of an outer Cr2O3 layer and an inner SiO2 layer. In wet gas, additional chromia whiskers were formed on top of the duplex scale. Chromia grains formed in wet gas were much sma...

Oxygen solubility in a series of binary austenitic Fe-Ni alloys has been measured at temperatures of 1000–1150 °C, under oxygen partial pressures corresponding to the Fe/FeO equilibrium. Oxygen activities controlled in Rhines packs or by flowing CO/CO2 gas mixtures yielded the same results within measurement uncertainty, showing that carbon has no...

Model alloys Ni–(5, 10, 20, 25, 30 wt%)Cr were exposed to Ar–20CO2 and Ar–20O2 at 700 °C. Samples were electropolished before reaction to avoid cold-working effects and, as a result, to reveal the effect of alloy bulk diffusion. All alloys underwent breakaway oxidation in CO2, forming an external Ni-rich oxide scale and other oxides internally. In...

Model Ni-Cr alloys containing 5, 10, 15, 20, 25 and 30 wt% Cr were oxidized in Ar-20 vol% CO2 gas mixtures at temperatures of 650, 700 and 800°C. In general, multi-layered oxide scales were observed on the surface after reaction. With increased alloy Cr content, the oxide structure changed from external NiO, plus intermediate inner oxides and an in...

Model alloys, Fe–20Cr and Fe–20Cr–20Ni without and with Si (0.1, 0.2 and 0.5 wt%), were exposed to Ar–20CO2 and Ar–20CO2–20H2O gases at 650 °C. The undoped alloys underwent breakaway corrosion in both gases, forming iron-rich oxide scales and internal carbide precipitates. Silicon additions markedly improved oxidation and carburization resistance o...

The design of new austenitic alloys based on the Fe–Ni–Cr system requires knowledge of their oxygen permeability. Data are available for pure Fe and Ni but not for Fe–Ni alloys. Wagner’s model for internal oxidation is used to evaluate the oxygen permeability in Fe–Ni alloys. Internal oxidation of Fe–Ni–Cr alloys carried out at 1150 and 1100 °C in...

Combining thermodynamic concepts with first-principles calculations, we study the solubility of oxygen atoms (O) in nickel. In our approach, we include the possible formation of oxygen clusters ( ) and vacancies-oxygens clusters (VOn and ). We show that the vacancy-oxygens interactions are strong (approximately 1 eV) and would induce a large concen...

Four chromised and aluminised coatings, with and without an intermediate nickel layer, were produced by pack cementation. The nickel layer was deposited onto a T91 steel substrate prior to the pack cementation process to limit interdiffusion of elements between the coatings and the substrate. The coated and uncoated steels were exposed to Ar-20CO2-...

Abstract Fundamental insights into the mechanism of breakaway oxidation in Fe9Cr1Mo steel are deduced, through advanced characterisation and modelling. Degradation at 600 °C/∼42 bar CO2 for ∼20,000 h is emphasised: conditions relevant to components such as the finned superheater tubes used for advanced gas-cooled nuclear reactors. It is shown that...

Model Ni-Cr alloys containing 5, 10, 15, 20, 25 and 30 wt% Cr were oxidized in Ar-20 vol% CO2 gas mixtures at temperatures of 650, 700 and 800oC. In general, multi-layered oxide scales were observed on the surface after reaction. With increased Cr alloy content, the oxide structure changed from external NiO, plus intermediate inner oxides and an in...

Heat-resisting alloys contain chromium and/or aluminium to provide protective scales. The concentration of each metal necessary to form an external scale is calculated from an analysis of alloy diffusion. A similar approach is used to describe the growth of single-phase, solid solution scales. Depletion of a scale-forming metal alters alloy sub-sur...

Mixed oxidant atmospheres are common, but predicting the nature of the scales developed in these gases is difficult. Phases formed in contact with oxidising-carburising or oxidising-nitriding gases can be predicted using thermochemical diagrams. However, because different oxidant activities prevail within the scale, secondary phases can form, refle...

At high temperatures, most metals will inevitably oxidise over a wide range of conditions. The practical issues of material lifetimes and corrosion protection methods therefore centre around the rate of oxidation and how to control reaction morphology. Answers to the second question turn out to be rather interesting and involve the need for a funda...

Reaction of a pure metal with a single oxidant (oxygen, carbon, nitrogen, sulphur or a halogen) is considered. Most metals present in alloys used at high temperature form solid oxides, carbides or nitrides, but sulphides have lower melting points than the corresponding oxides, and liquid formation must sometimes be considered. We commence by survey...

In 1988, Kofstad [1] wrote, ‘It is well known that most technical steels oxidise faster in water vapour or in air or combustion gases containing water vapour than in dry oxygen. The reasons for this are poorly understood’. At a subsequent workshop on high-temperature corrosion [2], it was concluded that understanding remained incomplete. Since then...

We have examined at some length the development of a theoretical basis for understanding and predicting the outcomes of high-temperature alloy corrosion reactions. On the one hand, thermodynamic analysis is aimed at predicting the identity of reaction products. On the other, diffusion analysis seeks to predict the rates of mass transfer in reaction...

Carbon dioxide is oxidising to all practical alloys, forming external oxide scales. Higher alloy Cr levels are needed to achieve protection in CO2 rather than in O2, because scaling is faster. In addition, CO2 sometimes penetrates oxide scales, leading to the development of high carbon activities and carburisation of the underlying alloy. In this c...

The high-temperature corrosion processes considered so far lead to the formation of solid reaction products, and their kinetics are in most cases controlled by solid-state diffusion. However, gaseous and liquid corrosion products are also possible. Because mass transport in liquids is so much faster than in solids, and in the gas phase faster still...

Alloys used at high temperatures are subjected to duty cycles which vary widely among applications. These range from the rather short operating periods of propulsion engines through the weeks, months or even years of chemical processing or power generation plant campaigns. In all cases, however, start up and shut down involve more or less rapid tem...

Various combustion, gasification and petrochemical processes produce hot carbonaceous gases. Carbon activities in these gases can be high under reducing conditions, causing carbon dissolution into alloys and their carburisation. At low to moderate temperatures, gases can supersaturate with carbon. In this case, contact with alloys can lead to carbo...

As seen in the previous chapter, we wish to predict which reaction products form when a particular alloy is exposed to a given gas, and the effects of temperature and pressure on the outcome. This requires the use of chemical thermodynamics, and in particular the use of phase equilibria. The rates at which the products form are usually governed by...

Sulphur is a relatively strong corrodent (or oxidising agent) as seen from the free energies of metal sulphide formation shown in Table 8.1 . It is frequently present in fossil fuels and causes special forms of corrosion in petroleum and petrochemical processes based on these feedstocks, as well as in combustion processes. Because metal sulphides a...

Practical heat-resisting alloys have multiple components (Tables 5.1 and 9.1 Table 5.1 Table 9.1), nearly all of which are susceptible to oxidation in a wide range of environments. When these alloys are exposed at high temperatures, an initial, transient period of reaction, in which all alloy components oxidise, is followed by a steady-state reacti...

As recognised in Chapter 5 , when an alloy component is selectively oxidised but cannot reach the surface quickly enough to develop a scale, then internal oxidation results. Furthermore, an alloy which initially contains a sufficient amount of the reacting metal to form a scale can become depleted in that component to the extent that internal oxida...

Nickel-base alloys were exposed to flowing supercritical CO2 (P = 20MPa) at temperatures of 700 to 1000°C for up to 1000 h. For comparison, 316L stainless steel was similarly exposed at 650°C. To simulate likely service conditions, tubular samples of each alloy were internally pressurised by flowing CO2, inducing hoop stresses up to 35 MPa in the t...

To reduce the massive CO 2 emission from coal-fired power plants, oxy-fuel combustion has been considered as one of the most effective and promising technologies to fulfil this goal. In this process, coal is burnt in pure O 2 rather than air. So, the resultant flue gas is mainly CO 2 and H 2 O, making subsequent CO 2 capture and sequestration feasi...

High purity iron and a low carbon, low silicon steel were oxidised at temperatures of 800 to 1200 o C, in atmospheres of N 2 -H 2 -H 2 O and N 2 -O 2 -H 2 O. Scales of wüstite grew at low oxygen potentials, and of FeO/Fe 3 O 4 /Fe 2 O 3 at high potentials. In both cases, kinetics were parabolic after an initial transient period. The iron and steel...

Model alloys Fe-20Cr-2Mn and Fe-20Cr-20Ni-2Mn (wt.%) were exposed to Ar-20CO(2)-(20H(2)O) gases at 650 degrees C. Oxide formation was affected by alloy Mn diffusion, reaction temperature and gas composition. In dry CO2, both alloys initially formed thin scales of Mn3O4, Cr2O3 and MnCr2O4 layers. In wet CO2, Fe-20Cr(2)-Mn formed a thin, duplex scale...

Model alloys Fe-9Cr, Fe-20Cr (wt.%) and these alloys doped with 2%Mn or 0.5%Si were exposed to Ar-20%CO2-20%H2O-(0, 0.5)%SO2 (vol.%) gas at 811°C for up to 500h. The Fe-9Cr and Fe-9Cr-2Mn underwent breakaway oxidation in both gases. The Fe-9Cr-0.5Si developed Cr2O3 scale in sulphur-free gas, but entered breakaway in sulphur-bearing gas. The Fe-20Cr...

High Temperature Oxidation and Corrosion of Metals, Second Edition, provides a high level understanding of the fundamental mechanisms of high temperature alloy oxidation. It uses this understanding to develop methods of predicting oxidation rates and the way they change with temperature, gas chemistry, and alloy composition. The book focuses on the...

Wagner's model of internal oxidation allows the prediction of an alloy's critical concentration of oxide forming metal required to achieve a protective oxide scale at high temperatures. The model depends on oxygen permeability in the alloy, but this parameter has not been evaluated for the Fe-Ni system, and the influence of carbon-bearing gases is...

The high temperature air oxidation of the two conventionally cast Ni-based superalloys Rene 80 containing 92wtppm boron and CM 247 containing 110wtppm of boron was studied at temperatures between 850 and 1050°C and times ranging from 1 to 100h. Analysis by GD-OES and SEM/WDX/EBSD revealed the surface scale on Rene 80 after exposure at 1050°C to con...

Model alloys, Fe-20Cr and Fe-20Cr-20Ni (wt%), and these alloys doped with 0.5% Si or 2% Mn, were exposed to Ar-20%CO2- 20%H2O-(0%, 0.1%, 0.5%, 1.0%)SO2 gas mixtures at 650°C. The reaction kinetics were analyzed gravimetrically and the reaction products were characterized using X-ray diffraction, scanning electron microscopy, and transmission electr...

Commercially available high pressure tubing materials SS316 and Hastelloy-C276, containing a similar chromium content about 17 wt%, were internally pressurised by flowing supercritical CO 2 at 20 MPa and heated externally, to 650 °C in the case of SS316, and 650–750 °C in the case of Hastelloy-C276. The stainless steel was found to be corroded by b...

Model alloys Fe-9Cr, Fe-20Cr and Fe-20Cr-20Ni (wt.%) with 0.1% Ce or 2% Mn were exposed to Ar-20CO2 and Ar-20CO2-20H2O gas mixtures at 650°C. Ferritic alloys underwent breakaway oxidation in both gases. Manganese additions significantly improved the oxidation resistance of Fe-20Cr in dry but not wet CO2. Water vapour accelerated internal oxidation...

Model alloys Fe-20Cr and Fe-20Cr-20Ni (wt.%) and these alloys doped with 0.5% Si or 2% Mn were exposed to Ar-20%CO2-20%H2O-(0%, 0.1%, 0.5%, 1.0%) SO2 gas mixtures at 650°C. Alloys of Fe-20Cr-(2Mn) and Fe-20Cr-20Ni-(0.5Si) underwent breakaway oxidation in sulphur-free gases, forming thick iron-rich oxide scales and internal carbides. SO2 additions p...

Model alloys Fe-9Cr, Fe-20Cr and Fe-20Cr-20Ni (wt. %) with 0.1 and 0.2 % Si were exposed to Ar-20CO_2-20H_2O gas at 818^{\circ}C. The undoped alloys formed a thick iron-rich oxide scale. The additions of Si reduced scaling rates of Fe-9Cr to some extent but significantly suppressed the formation of iron oxide scales on Fe-20Cr and Fe-20Cr-20Ni. Car...