scholarly journals Kinetics of oxide scale growth on a (Ti, Mo)5Si3 based oxidation resistant Mo-Ti-Si alloy at 900-1300∘C

2019 ◽  
Vol 38 (2019) ◽  
pp. 533-540 ◽  
Author(s):  
Sanjib Majumdar ◽  
Pankaj Kumar Singh ◽  
Ajoy Kumar Pandey ◽  
G.V.S. Nageswara Rao

AbstractHigh-temperature oxidation behaviour of Mo-40Ti-30Si (at.%) alloy was investigated in the temperature regime of 900-1300∘C in air. Isothermal weight change data recorded up to 100 h of exposure revealed parabolic weight gain kinetics at all the tested temperatures. The protective oxide scale composed with SiO2 (silica) and TiO2 (titania) forming a duplex oxide microstructure consisting of TiO2 particles embedded in the continuous SiO2 matrix. The oxide scale showed parabolic growth kinetics, and the activation energies for the scale growth were found to be 72.2 kJ/mol in 900-1200∘C and 324.9 kJ/mol in 1200-1300∘C. The kinetics of the protective scale growth on the alloy surface was mainly controlled by the growth of the silica film and the inward diffusion of oxygen through the duplex oxide layer.

2011 ◽  
Vol 312-315 ◽  
pp. 1097-1105
Author(s):  
Hisao Fujikawa

Three studies on the oxidation behaviour of austenitic stainless steels were described in the present paper. (1) High temperature oxidation behaviour and its mechanism in austenitic stainless steels with high silicon: Sulfur contained as impurity in steel showed a harmful influence to the oxidation resistance of 19Cr-13Ni-3.5Si stainless steels. It was found that the abnormal oxidation was caused from the surroundings of MnS inclusions. (2) Effect of a small addition of yttrium on high temperature oxidation resistance of Si-containing austenitic stain less steels: The oxidation resistance of 19Cr-10Ni-1.5Si steels was improved remarkably even with only 0.01%Y addition, which is the same concentration as added for de-oxygenation. Y was enriched at the grain boundary of oxide scale and metal-oxide interface. It was suggested that Y-containing steels shoed good oxidation resistance, because the enriched Y at the grain boundary and metal-oxide interface prevented the diffusion of iron and oxygen ions through the oxide scale. (3) Effect of grain size on the oxidation behaviour of austenitic stainless steels: Type 304, 316 and 310 steels with finer grain size showed better oxidation resistance than those with coarser grain size at 850°C. The oxide scale of steels with coarser grain size easily spalled during the cooling process.


2013 ◽  
Vol 333 ◽  
pp. 149-155 ◽  
Author(s):  
H. Fujikawa ◽  
Y. Iijima

The effect of grain size on high temperature oxidation behaviour of 316 steels at 700º, 850º and 1000°C in air was studied. The results show that the mass gain increases with the increase of grain size. Particularly, the gradient of mass gain is severe in at lower oxidation temperatures. In the oxidation at temperatures of more than the solid solution temperature, the grain size before the oxidation changed to coarse grain size. Therefore, in this case, it is not enough to estimate the oxidation behaviour by the grain size before the oxidation. The exfoliation of oxide scale is severe in steel with coarse grains. Over 850°C, the exfoliation was observed in 316 steel with coarse grains. At 1000°C, the oxide scale of 316 steel was exfoliated, but it was extreme in the coarse grains. Cr, Mn and Si in the oxide scale were enriched in the oxide scale of the steel with fine grains. Particularly, Si was remarkably enriched at the metal-oxide interface and grain boundaries.


2014 ◽  
Vol 900 ◽  
pp. 673-676 ◽  
Author(s):  
Jian Guo Peng ◽  
Mou Cheng Li

The oxidation kinetics of 2205 stainless steel in humid air at high temperature were studied by adopting thermal-gravimetric analysis (TGA). The morphology, composition and microstructure of the oxide scales were analyzed using SEM and XRD. The experiment showed that few scales form on the surface of DSS2205 at less than 800°C.With increasing temperature above 800°C, thickness of oxide scales increase and the inner oxides can be found. The nodules can be observed when the temperature reaches 1050°C.


2017 ◽  
Vol 62 (2) ◽  
pp. 1099-1104
Author(s):  
Yong Hwan Kim ◽  
Jeong-Jung Oak ◽  
Ki-Chang Bae ◽  
Wook Jin Lee ◽  
Yong Ho Park

AbstractThe oxidation kinetics of forged 12Cr-MoVW steel was investigated in an air (N2+O2) atmosphere at 873-1073 K (Δ50 K) using thermogravimetric analysis. The oxidized samples were characterized using X-ray diffraction, and the surface and cross-sectional morphologies were examined using scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy. The forged 12Cr-MoVW steel samples exhibited parabolic behavior and a low oxidation rate compared with their as-cast counterparts. A protective oxide layer was uniformly formed at relatively low temperature (≤973 K) for the forged samples, which thus exhibited better oxidation resistance than the as-cast ones. These oxides are considered solid-solution compounds such as (Fe, Cr)2O3.


2015 ◽  
Vol 15 (2) ◽  
pp. 14-21
Author(s):  
J. Małecka

Abstract The paper presents research results of isothermal oxidation of Ti-25Al-12.5Nb alloy. Oxidation was carried out in 9%O2+0,2%HCl+0,08%SO2+N2 atmosphere at the temperature of 700 and 750 ºC.


Author(s):  
I. G. Wright ◽  
V. K. Sethi ◽  
V. Nagarajan

The rate of wastage of an alloy surface subjected to erosion under conditions where high-temperature oxidation can occur can be significantly greater than that arising from erosion alone. This is because the erosion conditions can act to accelerate the oxidation process by causing regular shedding of the otherwise protective oxide scale. It is suggested that an important parameter in determining the rate of erosion-oxidation is the erodent flux, since the time available for oxide growth (or regrowth) in a given area is determined by the interval between successive erodent impacts. Using this simple premise, an approach is suggested by which the rate of erosion-oxidation can be related to the factors that control the alloy oxidation process, and those that describe the erosive environment. The assumptions made are examined, and some of the implications of this approach are discussed.


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