scholarly journals Oxidation Behavior of Ta–Al Multilayer Coatings

Coatings ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 810 ◽  
Author(s):  
Yung-I Chen ◽  
Nai-Yuan Lin ◽  
Yi-En Ke
Keyword(s):  
Direct Current ◽  
Multilayer Structure ◽  
Oxidation Behavior ◽  
Oxidation Process ◽  
Growth Direction ◽  
Multilayer Coatings ◽  
Ambient Atmosphere ◽  
Preferential Oxidation ◽  
Oxidation Depth ◽  
Al Oxide

Ta–Al multilayer coatings were fabricated through cyclical gradient concentration deposition by direct current magnetron co-sputtering. The as-deposited coatings presented a multilayer structure in the growth direction. The oxidation behavior of the Ta–Al multilayer coatings was explored. The results specified that Ta-rich Ta–Al multilayer coatings demonstrated a restricted oxidation depth after annealing at 600 °C in 1% O2–99% Ar for up to 100 h. This was attributed to the preferential oxidation of Al, the formation of amorphous Al-oxide sublayers, and the maintenance of a multilayer structure. By contrast, Ta2O5 formed after exhausting Al in the oxidation process in an ambient atmosphere at 600 °C which exhibited a crystalline Ta2O5-amorphous Al-oxide multilayer structure.

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.

Oxidation Behavior of β-Sialon Ultrafine Powders Prepared by the Combined Sol-Gel and Microwave Carbothermal Reduction Nitridation Method

2018 ◽  
Vol 281 ◽  
pp. 34-39
Author(s):  
Fa Liang Li ◽  
Fang Fu ◽  
Li Lin Lu ◽  
Hai Jun Zhang ◽  
Shao Wei Zhang
Keyword(s):  
Activation Energy ◽  
Carbothermal Reduction ◽  
Oxidation Behavior ◽  
Oxidation Process ◽  
Sol Gel ◽  
Probable Mechanism ◽  
Ultrafine Powders ◽  
Isothermal Thermogravimetry ◽  
Temperature Range ◽  
Mechanism Function

Ultrafine powders of β-Sialon were prepared by the combined sol-gel and microwave carbothermal reduction nitridation method, and their oxidation process was studied by a non-isothermal thermogravimetry method. The results indicated that two different mechanism functions respectively corresponded to the initial and final oxidation stages. The reverse Jander equation with activation energy of 240.5 kJ/mol and the Avrami-Erofeev equation with activation energy of 410.7 kJ/mol were respectively identified as the most probable mechanism function for the initial and final oxidation stages in the temperature range of 1423-1623 K.

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.

Long-term stable direct current bias operation in electro-optic polymer modulators with an electrically compatible multilayer structure

1997 ◽  
Vol 71 (16) ◽  
pp. 2236-2238 ◽  
Author(s):  
Yongqiang Shi ◽  
Wenshen Wang ◽  
Weiping Lin ◽  
David J. Olson ◽  
James H. Bechtel
Keyword(s):  
Direct Current ◽  
Multilayer Structure ◽  
Electro Optic ◽  
Direct Current Bias ◽  
Polymer Modulators

On the oxidation resistance of superhard Ti–Si–C–N coatings

2008 ◽  
Vol 23 (9) ◽  
pp. 2420-2428 ◽  
Author(s):  
Yan Guo ◽  
Shengli Ma ◽  
Kewei Xu ◽  
Tom Bell ◽  
Xiaoying Li ◽  
...  
Keyword(s):  
Grain Size ◽  
Chemical Vapor Deposition ◽  
Oxidation Resistance ◽  
Vapor Deposition ◽  
Silicon Content ◽  
Oxidation Behavior ◽  
Oxidation Process ◽  
Chemical Vapor ◽  
Surface Morphologies ◽  
The Relationship

The oxidation behavior of three types of plasma-enhanced chemical vapor deposition (PECVD) processed Ti–Si–C–N coatings with silicon content ranging from 4.3 to 11.6 at.% has been investigated at high temperatures. Systematic characterization was conducted to study the evolution of composition, phase constituents, hardness, surface morphologies, microstructures, and grain size during oxidation. A two-stage oxidation process was observed between 700 and 1000 °C for all three coatings. Experimental results indicate that a superhardness of 40 GPa can be maintained up to 700, 800, and 850 °C for 4.3, 7.4, and 11.6 at.% Si coatings, respectively; the dual-phased 7.4 and 11.6 at.% Si coatings show a better oxidation resistance than the single-phased 4.3 at.% Si coating. On the basis of the results, a mechanism is proposed to explain the relationship between the nanostructure and oxidation behavior.

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