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oxidation behavior of ammonium in a 3-dimensional biofilm-electrode reactor

Journal of Environmental Sciences 2013年第12期25卷 2403-2409页

作者： Jinjing Tang Jinsong Guo Fang Fang Youpeng Chen Lijing Lei Lin Yang Key Laboratory of Three Gorges Reservoir Region’s Eco-Environment (Ministry of Education) Chongqing University School of Chemistry and Chemical Engineering Chongqing University

Excess nitrogenous compounds are detrimental to natural water systems and to human health. To completely realize autohy- drogenotrophic nitrogen removal, a novel 3-dimensional biofilm-electrode reactor was designed. Titanium was electroplated with ruthenium and used as the anode. Activated carbon fiber felt was used as the cathode. The reactor was separated into two chambers by a permeable membrane. The cathode chamber was filled with granular graphite and glass beads. The cathode and cathode chamber were inhabited with domesticated biofilm. In the absence of organic substances, a nitrogen removal efficiency of up to 91% was achieved at DO levels of 3.42 ± 0.37 mg/L when the applied current density was only 0.02 mA/cm^2. The oxidation of ammonium in biofilmelectrode reactors was also investigated. It was found that ammonium could be oxidized not only on the anode but also on particle electrodes in the cathode chamber of the biofilm-electrode reactor. oxidation rates of ammonium and nitrogen removal efficiency were found to be affected by the electric current loading on the biofilm-electrode reactor. The kinetic model of ammonium at different electric currents was analyzed by a first-order reaction kinetics equation. The regression analysis implied that when the current density was less than 0.02 mA/cm^2, ammonium removal was positively correlated to the current density. However, when the current density was more than 0.02 mA/cm^2, the electric current became a limiting factor for the oxidation rate of ammonium and nitrogen removal efficiency.

关键词： autotrophic biofilm-electrode nitrogen removal ammonium oxidation behavior

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oxidation behavior of non-stoichiometric(Zr,Hf,Ti)C_(x) carbide solid solution powders in air

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Journal of Advanced Ceramics 2021年第4期10卷 741-757页

作者： Huilin LUN Yi ZENG Xiang XIONG Ziming YE Zhongwei ZHANG Xingchao LI Haikun CHEN Yufeng LIU State Key Laboratory of Powder Metallurgy Central South UniversityChangsha 410083China Institute of Advanced Structure Technology Beijing Institute of TechnologyBeijing 100081China Science and Technology of Advanced Functional Composites Laboratory Aerospace Research Institute of Materials&Processing TechnologyBeijing 100076China

Multi-component solid solutions with non-stoichiometric compositions are characteristics of ultra-high temperature carbides as promising materials for hypersonic ***,for group IV transition-metal carbides,the oxidation behavior of multi-component non-stoichiometric(Zr,Hf,Ti)C_(x)carbide solid solution has not been clarified *** present work fabricated four kinds of(Zr,Hf,Ti)C_(x)carbide solid solution powders by free-pressureless spark plasma sintering to investigate the oxidation behavior of(Zr,Hf,Ti)C_(x)in *** effects of metallic atom composition on oxidation resistance were *** results indicate that the oxidation kinetics of(Zr,Hf,Ti)C_(x)are composition dependent.A high Hf content in(Zr,Hf,Ti)C_(x)was beneficial to form an amorphous Zr-Hf-Ti-C-0 oxycarbide layer as an oxygen barrier to enhance the initial oxidation ***,an equiatomic ratio of metallic atoms reduced the growth rate of(Zr,Hf,Ti)O_(2)oxide,increasing its phase stability at high temperatures,which improved the oxidation activation energy of(Zr,Hf,Ti)C_(x).

关键词： ultra-high temperature ceramics(UHTCs) (Zr,Hf,Ti)C_(x)carbides oxidation behavior oxidation resistance free-pressureless spark plasma sintering

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oxidation behavior of boron-containing(Zr,Ti)C_(x)B_(y)solid solution ceramics at 1600℃in air

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Journal of Advanced Ceramics 2023年第10期12卷 1989-2002页

作者： Huilin Lun Yi Zeng Xiang Xiong Houbu Li State Key Laboratory of Performance and Structural Safety for Petroleum Tubular Goods and Equipment Materials CNPC Tubular Goods Research InstituteXi’an 710077China State Key Laboratory of Powder Metallurgy Central South UniversityChangsha 410083China Key Laboratory of Petroleum Tubular Goods and Equipment Ouality Safety for State Market Regulation CNPC Tubular Goods Research InstituteXi’an 710077China

Multicomponent boron-containing carbide coatings(i.e.,(Zr,Ti)C_(x)B_(y))on a C/C composite show good ablation ***,the high-temperature oxidation behavior of this new type of boron-containing(Zr,Ti)C_(x)B_(y)solid solution ceramics has not been clarified *** present work fabricated(Zr,Ti)C_(x)B_(y)solid solution block ceramics by spark plasma sintering,and their oxidation behavior at 1600℃in air(N2–20-vol%O2)was investigated for the first *** effects of boron on the oxidation resistance of(Zr,Ti)C_(x)B_(y)ceramics were *** results indicate that the(Zr,Ti)C_(x)B_(y)ceramics display good oxidation resistance with the parabolic rate law describing the oxidation *** the trace solution of boron(0.5 wt%)into(Zr,Ti)Cx,the oxidation resistance of carbide ceramics is significantly enhanced,leading to a decrease of 30%in the oxidation rate *** formed oxide scale in the(Zr,Ti)C_(x)B_(y)ceramics is dense,and the interlayer shows stronger ability to inhibit inward diffusion of *** addition,the introduction of boron leads to more negative binding energy of(Zr,Ti)C_(x)B_(y)and improves the oxidation resistance of carbides.

关键词： ultra-high-temperature ceramics(UHTCs) (Zr,Ti)CxBy solid solution oxidation behavior oxidation resistance

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oxidation behavior of the Fe-36Al-0.09C-0.09B-0.04Zr alloy at 1250℃

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International Journal of Minerals,Metallurgy and Materials 2010年第4期17卷 441-447页

作者： Jun-you Liu Feng Li Jie Liu Yi Zhang Jin-cheng Jiang Dun-xu Zou School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China Beijing BKDR Metallurgy Engineering ＆ Technology Co. Ltd. Beijing 100083 China China Iron ＆ Steel Research Institute Group Beijing 100081 China

To explore and study the Fe-A1 system alloy presenting exceptional oxidation resistance at high temperature, the Fe-36Al-0.09C-0.09B-0.04Zr alloy was designed and developed. The microstructure and hardness of the backing at 1250℃were analyzed and measured. Thermodynamics and kinetics of the oxidation behavior were also analyzed by X-ray diffraction, scanning electron micros- copy, and energy-dispersive X-ray spectroscopy techniques. The results show that the microstructttre of the Fe-36Al-0.09C-0.09B-0.04Zr alloy is FeAl phase at ambient temperature and is stable at 1250℃. It displays the excellent property of oxidation resistance because the oxide film has only the Al2O3 layer, and its oxidation kinetics curve obeys the parabolic law at 1250℃. The oxidation mechanism at 1250℃ is presumed that in the early oxidation period, the alloy oxidizes to form a large number of Al2O3 and a little Fe2O3, then, the enrichment of Al caused by Fe oxidization combines with O to form Al2O3.

关键词： Fe-alloy oxidation behavior oxide film oxidation thermodynamics oxidation kinetics

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oxidation behavior of multi-component Ta-W-Al-Ti alloy at 1173 K

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Rare Metals 2021年第7期40卷 1940-1948页

作者： Jia-Xin Li Yu-Hong Chen Zhang-Jun Bai Bao-Jun Zhao Liang Jiang Lan-Er Wu School of Materials Science and Engineering North Minzu UniversityYinchuan 750021China CNMC Ningxia Orient Group Co.Ltd Shizuishan 753000China School of Chemical Engineering The University of QueenslandBrisbaneQLD 4072Australia

Ta-W alloys have unique properties but their applications at high temperatures are restricted due to their poor oxidation *** addition of Al and Ti decreases the oxidation rate of the alloy,as Al-contained protective oxide layer could be *** this study,ternary and quaternary Ta-W alloys containing Al and Ti were prepared by hot press *** microstructures and oxidation behaviors of the alloys were studied at1173 *** results show that the oxidation kinetics of all alloys follows a parabolic law at short oxidation *** cyclic oxidation,the kinetics of quaternary alloys still obeys the parabolic law but that of ternary alloy has been changed into linear law kinetics after 8-h *** ternary alloy,an outer layer with dense and continuous alumina was formed during the initial stage,and phase transformation caused the oxides to peel *** comparison,the quaternary alloys depicted continuously solid solution of the oxides ***,Al and Ti played key roles in oxidation degree and affected the oxidation kinetics of ternary and quaternary alloys.

关键词： oxidation behavior Ta-W-based alloy Aluminum Titanium

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oxidation behavior of Ni-based superalloy GH738 in static air between 800 and 1000℃

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Rare Metals 2021年第3期40卷 616-625页

作者： Jue Wang Hao Xue Ying Wang Jiangsu Key Laboratory of Advanced Structural Materials and Application Technology Nanjing 211167China School of Materials Science and Engineering Nanjing Institute of TechnologyNanjing 211167China

The oxidation behavior of a nickel-based superalloy GH738 was studied by isothermal oxidation tests in still air at different temperatures,with exposure time up to 100 ***-kinetic curves were plotted using the mass gain *** surface and cross-sectional morphologies were observed by scanning electron microscopy(SEM).A composition analysis and an oxidation-product identification were conducted using energydispersive X-ray spectroscopy(EDS) and an X-ray diffraction(XRD),*** results showed that GH738 exhibited parabolic oxidation-kinetic curves,with stable parabolic-rate constants at each *** activation energy of oxide growth was calculated to be329.6 kJ·mol^(-1).Cr_(2) O_(3)(chromia) was the external oxidation product at 800℃.A TiO_(2)-Cr_(2) O_(3) double-layer structure was formed at 900℃.The position of TiO_(2) changed from the oxide-metal interface to the air-oxide interface by the diffusion of Ti atoms in chromia during the oxidation time at this *** was observed in the Cr_(0.12)Ti_(0.78)O_(1.74)-Cr_(2) O_(3) multi-layer oxide of at 1000℃,which increased the oxidation *** all the tests,the main internal oxide was always Al_(2) O_(3).The entire GH738 oxidation process was interpreted by the competitive diffusion of elements(Cr,Ti,Ni,etc.) in metal matrix and chromia,while a schematic diagram of oxidation process was proposed.

关键词： GH738 oxidation behavior Diffusion Multilayer structure

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oxidation behavior of Ni-based superalloy GH4738 under tensile stress

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Rare Metals 2024年第8期43卷 3913-3920页

作者： Ji-Chong Hu Hai-Liang Huang Chong-Chong Wu Xiao-Yu Sun Jie Wang Yan-Hong Yang Jing-Long Qu Liang Jiang Jin-He Dou Yang Chen Institute for Advanced Studies in Precision Materials Yantai UniversityYantai 264005China Department of Management and Engineering Linkoping University58183LinkopingSweden Shi-Changxu Innovation Center for Advanced Materials Institute of Metal ResearchChinese Academy of SciencesShenyang110016China Gaona Aero Material Co. LtdBeijing 100081China College of Artificial Intelligence and Big Data Shandong First Medical University and Shandong Academy of Medical SciencesJinan250117China

Revealing the oxidation behavior of superalloys is crucial for optimizing material properties and extending service *** study investigated the oxidation behavior of superalloy GH4738 under stress states at 850℃.High-throughput specimens were fabricated to withstand different stresses at the same *** oxidation s amples were analyzed using the mass gain method to obtain oxidation kinetic *** results show that the external stress below 200 MPa could improve the oxidation resistance of the *** tensile stress increasing,the oxide layer becomes thinner,denser and more complete,while internal oxidation *** tensile stress alters the structure of the external oxide layer from a two-layer to a threelayer *** Cr_(2)O_(3) oxide layer inhibits the outward diffusion of Ti,leading to Ti enrichment at the oxide-matrix interface and altering the oxidation mechanism of GH4738.

关键词： Ni-based Superalloy oxidation behavior Tensile stress Oxide layer

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oxidation　behavior　of　La_2O_3　Oxide　Dispersion　Strengthened　Aluminum－Diffusional　Coating

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Journal of Rare Earths 1994年第2期12卷 149-152页

作者：彭晓李铁藩于瀛大徐淑华关若男李日升 Acad Sinica Shenyang China

NiAl-La2O3 compostite coating was prepared by Ni-La2O3 electrodeposited and pack aluminized at 1173 K on Ni-base superalloy K38. The result of oxidation in air at 1273 K for 20 h shows that the oxidation rate of NiAl-La2O3 coating is remarkably lower than that of NiAl-La2O3 free coating. The oxide film surface morphology of NiAl-La2O3 composite coating was obviously modified after oxidation. HREM study of the fine structure of aluminum oxide on the composite coating shows that La2O3 particles with diameter of 10￣40 nm were incorporated into u-Al2O3 layer. It is believed that La2O3 dispersive particles improve NiAl coating oxidation resistance by a way to influence aluminum layer microstructure and to modify cationic transfer behavior of the layer growth.

关键词： La_2O_3 Dispereion-strengthened Aluminum-diffusional coating oxidation behavior

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High-temperature oxidation behavior of HVOF-sprayed rare earth-modified WC-12Co coating

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Rare Metals 2022年第11期41卷 3895-3902页

作者： Zong-Qiu Hang Nai-Yuan Xi Yan Liu Yue Liu Hui Chen School of Materials Science and Engineering Southwest Jiaotong UniversityChengdu610031China

In this study,the CeO_(2)-modified WC-12 Co coatings were deposited on Q345 steel substrate using high-velocity oxygen fuel(HVOF) *** behavior of the modified coatings was analyzed in the range of 450-900℃ for different oxidation time to investigate the effects of oxidation time and temperature on the *** oxidation kinetics and oxidation mechanism of the modified coatings were *** results show that the oxides are mainly composed of WO_(3) and CoWO_(4) within 450-750℃ while the phases are different at 900 ℃.The CeO_(2)-modified coatings have good oxidation resistance when the oxidation temperature is below550℃ and the oxidation mechanism changes due to the occurrence of anomalous oxidation above 650℃.Moreover,the oxidation mass gain curves obey approximately a parabolic law in the temperature range of 450-650℃ at the initial stage but the later oxidation proceeds by a linear *** addition,based on the analysis of micromorphology and component of the prepared coating,the role of rare earth(RE) additives is obtained during high-temperature oxidization.

关键词： Rare earth HVOF WC-Co coating oxidation behavior

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Design and preparation of an ultra-high temperature ceramic by in-situ introduction of Zr_(2)[Al(Si)]_(4)C_(5) into ZrB_(2)-SiC:Investigation on the mechanical properties and oxidation behavior

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Journal of Advanced Ceramics 2021年第5期10卷 1082-1094页

作者： Lei YU Hui LIU Yaohui FU Weijiang HU Zhefei WANG Quan LIU Bo WEI Jian YANG Tai QIU School of Materials Engineering Changshu Institute of Technology^Changshu 215500China School of Petrochemical Engineerings Changzhou University Changzhou 213164China School of Materials Science and Engineering Nanyang Technological UniversitySingapore 639798Singapore College of Materials Science and Engineering Nanjing Tech UniversityNanjing 210009China

Novel ZrB_(2)-matrix composites were designed and prepared by in-situ introducing SiC and Zr_(2)[Al(Si)]_(4)C_(5) simultaneously for the first *** obtained composites were dense and showed good mechanical properties,especially the strength and toughness,706 MPa and 7.33 MPa·m^(1/2),respectively,coupled with high hardness of 21.3 GPa,and stiffness of 452 *** and Zr_(2)[Al(Si)]_(4)C_(5) constituted a reinforcing system with synergistic effects including grain refinement,grain pull-out as well as crack branching,bridging,and ***,the oxidation results of the composites showed that the oxidation kinetics followed the parabolic law at 1600℃,and the oxidation rate constants increased with the increase of Zr_(2)[Al(Si)]_(4)C_(5) *** formation and evolution model of the oxidation structure was also investigated,and the oxide scale of the composite exhibited a three-layer structure.

关键词： ZrB_(2)-matrix composites ultra-high temperature ceramics(UHTCs) mechanical properties strengthening and toughening mechanism oxidation behavior

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