scholarly journals Effect of ZrB2 addition on the oxidation behavior of Si-SiC-ZrB2 composites exposed at 1500°C in air

2017 ◽  
Vol 16 (1) ◽  
pp. 14-22
Author(s):  
Claudio D’Amico ◽  
Giovanni Bianchi ◽  
Elisa Padovano ◽  
Sara Biamino ◽  
Alberta Aversa ◽  
...  
Keyword(s):  
High Temperature ◽  
Oxidation Behavior ◽  
Oxidation Process ◽  
Oxidation Mechanism ◽  
Industrial Applications ◽  
Reactive Infiltration ◽  
Diffraction Patterns ◽  
Carbide Ceramics ◽  
Sic Composites ◽  
Silicon Carbide Ceramics

Background: Silicon carbide ceramics obtained by reactive infiltration of silicon (SRI) have many industrial applications especially involving severe and high temperature conditions. In this study, the oxidation behavior in air of Si-SiC-ZrB2 systems at a high temperature (1500°C) for dwelling times of up to 48 hours was examined. Methods: The oxidation process was analyzed on the basis of elemental maps and X-ray diffraction patterns taken, respectively, on the core and on the surface of the specimens, together with weight gains and the average thicknesses of the resulting scale. Further, flexural strength at room temperature was examined as a function of different oxidation times. Results: The main chemical reactions and phase transformations involved in the oxidation process are reported. Several oxides were detected on the surface: zirconia, silica, zircon and 3-zirconium monoxide. All of the samples showed a parabolic oxidation kinetics, suggesting that the controlling mechanism was the diffusion; however, even after 48 hours, the oxidation process was not finished – indeed, all of the samples continued to gain weight. Conclusions: The oxidation of Si-SiC-ZrB2 material produced via SRI was slower compared with previously investigated ZrB2-SiC composites processed with a different techniques and tested in similar conditions. The oxidation mechanism was found to be consistent with the convection cells model.

scholarly journals High-temperature oxidation behavior of reaction-formed silicon carbide ceramics

1995 ◽  
Vol 10 (12) ◽  
pp. 3232-3240 ◽  
Author(s):  
Linus U.J.T. Ogbuji ◽  
M. Singh
Keyword(s):  
Silicon Carbide ◽  
Weight Loss ◽  
Oxidation Product ◽  
Oxidation Behavior ◽  
Light And Electron Microscopy ◽  
Initial Weight Loss ◽  
Temperature Oxidation ◽  
Carbide Ceramics ◽  
High Temperature Oxidation Behavior ◽  
Silicon Carbide Ceramics

The oxidation behavior of reaction-formed silicon carbide (RFSC) ceramics was investigated in the temperature range of 1100 to 1400 °C. The oxidation weight change was recorded by TGA; the oxidized materials were examined by light and electron microscopy, and the oxidation product by x-ray diffraction analysis (XRD). The materials exhibited initial weight loss, followed by passive weight gain (with enhanced parabolic rates, kp), and ending with a negative (logarithmic) deviation from the parabolic law. The weight loss arose from the oxidation of residual carbon, and the enhanced kp values from internal oxidation and the oxidation of residual silicon, while the logarithmic kinetics is thought to have resulted from crystallization of the oxide. The presence of a small amount of MoSi2 in the RFSC material caused a further increase in the oxidation rate. The only solid oxidation product for all temperatures studied was silica.

Oxidation Behavior of Amorphous Nano-Si3N4 Powders

2014 ◽  
Vol 602-603 ◽  
pp. 367-370 ◽  
Author(s):  
Jiang Bo Wen ◽  
Sheng Huang ◽  
Hong Jie Wang
Keyword(s):  
High Temperature ◽  
Partial Pressure ◽  
Mechanical Behavior ◽  
Low Temperatures ◽  
Traditional Method ◽  
Oxidation Behavior ◽  
Oxidation Process ◽  
Composite Ceramic ◽  
Intergranular Phase ◽  
Sintering Additives

The traditional method preparing Si3N4/Si2N2O composite ceramic is to sinter α-Si3N4 powder with additives at relatively high temperatures. But the intergranular phase transformed from the sintering additives can degrade the high-temperature mechanical behavior. Amorphous nanoSi3N4 is used to fabricate Si3N4/Si2N2O composite ceramic by its oxidation and nitridation without sintering additives at low temperatures. Thus, it is essential to study the oxidation behavior and mechanism of amorphous nanoSi3N4. Amorphous nanoSi3N4 powders were oxidized in different atmospheres, at varying temperatures and for various different length of time. The oxidation process and products was analyzed by means of XRD, TGA and FTIR. The results showed that amorphous nanoSi3N4 could be oxidized into SiO2 from 600°C to 1300°C. Below 1300°C, the oxidation became serious as the temperature increased. Besides, the longer the oxidation time and the lager the ratio of O2/N2 partial pressure was, the deeper the oxidation level was. When the temperature was above 1300°C, amorphous nanoSi3N4 was completely oxidized into SiO2.

Temperature-Driven Oxidation Behavior of Pure Iron Surface Investigated by Time-Resolved EXAFS Measurements

1998 ◽  
Vol 524 ◽  
Author(s):  
S. J. Doh ◽  
J. M. Lee ◽  
D. Y. Noh ◽  
J. H. Je
Keyword(s):  
Heat Treatment ◽  
Oxidation Behavior ◽  
Oxidation Process ◽  
Rapid Heating ◽  
Oxidation Mechanism ◽  
Front Surface ◽  
Time Resolved ◽  
Treatment Conditions ◽  
Surface Front ◽  
Prolonged Heat

ABSTRACTThe surface-front oxidation mechanism of iron was investigated by time-resolved, glancingangle Fe K-edge fluorescence EXAFS measurements at various oxidation temperatures of 200-700 C. The glancing angle was chosen according to the depth of the oxide layer, roughly 1500-2000A. The oxidation behavior under rapid heating(up to 600°C within 10 minutes) was compared with the slowly heated oxidation process using the Quick-EXAFS measurements. In the slowly heated process, Fe3O4 was the dominating phase at a relatively low temperature (300-400 C) initially. However, at a relatively high temperature (above 600°C), the Fe2O3 and FeO crystalline phases are gradually enriched as the successive oxidation process involving intrusive oxygen proceeded. Remarkably under a prolonged heat treatment above 600°C, the stable FeO phase that exists in a deep-lying interface structure and Fe2O3 phase eventually dominates the thick front-surface structure. In a quickly heated process, however, Fe3O4 phase is less dominating, which is contradictory to the commonly accepted oxidation models. The EXAFS results are discussed in conjunction with the x-ray diffraction features under the same heat treatment conditions.

Cyclic Oxidation Resistance of Co-10Cr-5Al-0.3Y Alloy at 800 oc

2014 ◽  
Vol 1015 ◽  
pp. 505-508
Author(s):  
Ling Yun Bai ◽  
Hong Hua Zhang ◽  
Huai Shu Zhang ◽  
Yun Xiang Zheng ◽  
Jun Huai Xiang
Keyword(s):  
Oxidation Resistance ◽  
Oxidation Rate ◽  
Cyclic Oxidation ◽  
Oxidation Behavior ◽  
Oxidation Process ◽  
Oxidation Mechanism ◽  
Local Zone

The cyclic oxidation behavior of Co-10Cr-5Al alloys with and without 0.3 at% Y doped in atmosphere at 800oC was investigated. The addition of 0.3 at.% Y increased the oxidation rate of the alloy and changed the oxidation mechanism. The scales grown the alloys with and without Y were both composed of an outer Co2O3layer and an inner complex layer of Al2O3, Co2O3and Cr2O3, except that the addition of 0.3 at% Y enhanced the adhesion of the scale. 0.3 at% Y agglomerated in local zone which accelerated the oxidation rate and was not conductive to the oxidation process of the Co-10Cr-5Al alloy.

Microstructure and oxidation behavior of C/C–ZrB 2 –SiC composites coated with SiC coating at high temperature

2015 ◽  
Vol 100 ◽  
pp. 421-427 ◽  
Author(s):  
Yu-Lei Zhang ◽  
Tian Fei ◽  
Wen-Ying Zeng ◽  
Bo-Xing Yang ◽  
He-Jun Li ◽  
...  
Keyword(s):  
High Temperature ◽  
Oxidation Behavior ◽  
Sic Composites

scholarly journals High-temperature Oxidation of Fe-Cr Steels in Steam Condition – A Review

2016 ◽  
Vol 1 (1) ◽  
pp. 107 ◽  
Author(s):  
Tedi Kurniawan ◽  
Farah Alia Binti Fauzi ◽  
Yuli Panca Asmara
Keyword(s):  
High Temperature ◽  
High Temperature Oxidation ◽  
Power Plants ◽  
Oxidation Behavior ◽  
Deep Understanding ◽  
Oxidation Mechanism ◽  
Corrosion Properties ◽  
Temperature Oxidation ◽  
Boiler Environment ◽  
Cr Steels

The development of supercritical (SC) and ultra-supercritical (USC) power plants requires materials with better corrosion properties. Deep understanding on the oxidation mechanism in the boiler environment is one of the important factors to support this development. In this work, high temperature oxidation of Fe-Cr steels in steam condition is reviewed.  Several mechanisms that explain the effect of water vapor in the oxidation behavior the steel were presented.

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