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oxidation and internal nitridation behaviors of a Ni-based superalloy Rene 65 during high-temperature homogenization

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Journal of Iron and Steel Research(International) 2023年第8期30卷 1622-1632页

作者： Xian-guang Zhang Jia-jun Chen Yang Zhou Lang Shui Dong-ping Xiao Jian-hui Fu Wen-chao Yang Huan Liu Ying-jie Ren Peng Shi Jian Zhang State Key Laboratory of Advanced Metallurgy University of Science and Technology Beijing(USTB)Beijing 100083China School of Metallurgical and Ecological Engineering University of Science and Technology Beijing(USTB)Beijing 100083China Chengdu Advanced Metal Materials Industrial Technology Institute Co. Ltd.Chengdu 610300SichuanChina Iron and State Key Laboratory of Metal Material for Marine Equipment and Application Anshan 114009LiaoningChina Pangang Group Research Institute Co. Ltd.Panzhihua 617000SichuanChina

Homogenization heat treatment is a key process to remove the micro-segregation and re-dissolve the undesired phases for wrought superalloy.The oxidation behavior of the wrought superalloy during the high-temperature homogenization process,however,was rarely studied.The oxidation film evolution and growth kinetics of an as-cast superalloy Rene 65 during the homogenization were systematically studied.The oxide film consists of Cr_(2)O_(3) external oxidation layer and dendritic TiO_(2) and Al_(2)O_(3) internal oxidation layer.And the growth kinetics of the oxide film followed a parabolic law.Internal nitridation occurs during the oxidation process,and TiN is apparently formed at the tip of internal oxidation layer.The originally formed TiN can be transformed into TiO_(2) or retained with the progress of oxidation.Meanwhile,the TiN is newly formed in the deeper matrix at the new oxidation-layer tip.Thermodynamic analyses revealed that there is a competition between the oxidation and nitridation.Nitridation can occur when the partial pressure of nitrogen exceeds the threshold of nitridation and the critical partial pressure ratio of nitrogen and oxygen.

关键词： Nickel-based superalloy Homogenization oxidation Kinetics Internal nitridation Thermodynamics

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oxidation Performance and Interdiffusion Behaviour of two MCrAlY Coatings on a Fourth-Generation Single-Crystal Superalloy

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Acta Metallurgica Sinica(English Letters) 2022年第4期35卷 679-692页

作者： K.J.Tan J.J.Liang X.G.Wang X.P.Tao J.Gong C.Sun Y.Z.Zhou X.F.Sun Institute of Metal Research Chinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China

The oxidation behaviour of a fourth-generation single-crystal superalloy without coating and with two types of MCrAlY coatings at 1140℃was studied.The results showed that both coatings greatly improved the oxidation resistance of the superalloy,and the addition of Hf further improved the oxidation resistance by pinning the oxide layer into the coating.Before and after oxidation,obvious Cr and Al interdiffusion was detected.Inward Cr diffusion induces the precipitation of a topologically close-packed phase,while the diffusion of Al affects the structure of theγ/γ’phase,the solubility of refractory elements,and the formation of an interdiffusion zone.

关键词： Superalloys Metal coatings oxidation Electron probe microanalyser(EPMA) Element diffusion

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Atmospheric Particle Hygroscopicity and the Influence by oxidation State of Organic Aerosols in Urban Beijing

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Journal of Environmental Sciences 2023年第2期124卷 544-556页

作者： Sinan Zhang Xiaojing Shen Junying Sun Yangmei Zhang Xiaoye Zhang Can Xia Xinyao Hu Junting Zhong Jialing Wang Shuo Liu State Key Laboratory of Severe Weather&Key Laboratory of Atmospheric Chemistry of CMA Chinese Academy of Meteorological SciencesBeijing 100081China School of Atmospheric Physics Nanjing University of Information Science&TechnologyNanjing 210044China

A hygroscopic tandem differentialmobility analyser(H-TDMA)was used to observe the sizeresolved hygroscopic characteristics of submicron particles in January and April 2018 in urban Beijing.The probability distribution of the hygroscopic growth factor(HGF-PDF)in winter and spring usually showed a bimodal pattern,with more hygroscopic mode(MH)being more dominant.The seasonal variation in particle hygroscopicity was related to the origin of air mass,which received polluted southerly air masses in spring and clean northwesterly air masses in winter.Particles showed stronger hygroscopic behaviour during heavy pollution episodes(HPEs)with elevated concentrations of secondary aerosols,especially higher mass fraction of nitrate,which were indicated using the PM2.5(particulate matter with diameter below 2.5μm)mass concentration normalised by CO mass concentration.The hygroscopic parameter(κ)values were calculated using H-TDMA(κhtdma)and chemical composition(κchem).The closure study showed thatκchem was overestimated in winter afternoon when compared withκhtdma,because the organic particle hygroscopic parameter(κorg)was overestimated in the calculations.It was influenced by the presence of a high concentration of hydrocarbon-like organic aerosol(HOA)with a weak water uptake ability.A positive relationship was observed betweenκorg and the ratio of oxygenated organic aerosol(OOA)and HOA,thereby indicating that the strong oxidation state enhanced the hygroscopicity of the particles.This study revealed the effect of local emission sources and secondary aerosol formation processes on particle hygroscopicity,which is of great significance for understanding the pollution formation mechanism in the North China Plain.

关键词： H-TDMA Hygroscopic parameter (κ) Organic aerosols oxidation state Heavy pollution episode (HPE)

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oxidation in Ca/K-1144 iron-based superconductors polycrystalline compounds

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Superconductivity 2023年第4期8卷 9-17页

作者： Zuhawn Sung Anastasiya Duchenko Giuseppe Celentano Jaeyel Lee Xiaobing Hu Nicola Pompeo Francesca Varsano Andrea Masi Fermi National Accelerator Laboratory BataviaIL 60510USA Universitàdegli Studi Roma Tre Dipartimento di Ingegneria IndustrialeElettronica e MeccanicaVia Vito Volterra 6200146 RomaItaly ENEA C.R.FrascatiVia Enrico Fermi 4500044 FrascatiItaly Department of Materials Science and Engineering Northwestern UniversityEvanstonIL 60208USA The NUANCE Center Northwestern UniversityIL 60208USA ENEA C.R.CasacciaVia Anguillarese 30100123 RomaItaly

Iron‐based superconductors(IBSCs)are a class of material under investigation for the development of superconducting wires in the low‐temperature‐high magnetic fields power application.Among the various families of IBSCs,the 1144 CaKFe_(4)As_(4) compound is a promising material able to achieve outstanding superconducting properties with a cheap and simple chemical composition.oxidation,in these compounds,is considered an obstacle for high intergranular critical current density,J_(c,GB).A study devoted to the evaluation of oxidation phenomena and their effects on the superconducting properties is thus needed in order to fully understand the involved mechanisms.From the evaluation of polycrystalline samples obtained by a mechanochemically assisted synthesis route,a degradation of the critical temperature and critical currents has been observed concurrently with oxygen accumulation at grain boundaries in open porosities.However,the crystalline structure at an atomic level seems not affected,as well as intragranular superconducting properties assessed by means of calorimetric methods.These results suggest that loss of superconducting properties in Ca/K‐1144 compounds following oxidation is significantly associated with the worsening of grain connectivity.

关键词： Grain boundaries Superconductivity oxidation Microstructure Iron based superconductors

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Migration and transformation of Sb are affected by Mn(Ⅲ/Ⅳ)associated with lepidocrocite originating from Fe(Ⅱ)oxidation

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Journal of Environmental Sciences 2022年第5期34卷 308-318页

作者： Yalu Shao Qian Sun Liangkai Wang Weiyong Zhan Hongwei Zhang Hua Zhong State Key Laboratory of Water Resources and Hydropower Engineering Science Wuhan UniversityWuhan 430072China School of Agriculture and Food The University of MelbourneVictoria 3010Australia College of Agricultural Sciences and Engineering Hohai UniversityNanjing 210098China

Antimony(Sb)is a recognized priority pollutant with toxicity that is influenced by its mi-gration and transformation processes.oxidation of Fe(Ⅱ)to Fe(Ⅲ)oxides,which is a com-mon phenomenon in the environment,is often accompanied by the formation of Mn(Ⅲ/Ⅳ)and might affect the fate of Sb.In this study,incorporated Mn(Ⅲ)and sorbed/precipitated Mn(Ⅲ/Ⅳ)associated with lepidocrocite were prepared by adding Mn(Ⅱ)during and after Fe(Ⅱ)oxidation,respectively,and the effects of these Mn species on Sb fate were inves-tigated.Our results indicated that the association of these Mn species with lepidocrocite obviously enhanced Sb(Ⅲ)oxidation to Sb(V),while concomitantly inhibiting Sb sorption due to the lower sorption capacity of lepidocrocite for Sb(V)than Sb(Ⅲ).Additionally,Mn oxide equivalents increased in the presence of Sb,indicating that Sb oxidation by Mn(Ⅲ/Ⅳ)associated with lepidocrocite was a continuous recycling process in which Mn(Ⅱ)released from Mn(Ⅲ/Ⅳ)reduction by Sb(Ⅲ)could be oxidized to Mn(Ⅲ/Ⅳ)again.This recycling pro-cess was favorable for effective Sb(Ⅲ)oxidation.Moreover,Sb(Ⅴ)generated from Sb(Ⅲ)ox-idation by Mn(Ⅲ/Ⅳ)enhanced Mn(Ⅱ)sorption at the beginning of the process,and thus favored Mn(Ⅲ/Ⅳ)formation,which could further promote Sb(Ⅲ)oxidation to Sb(V).Over-all,this study elucidated the effects of Mn(Ⅲ/Ⅳ)associated with lepidocrocite arisen from Fe(Ⅱ)oxidation on Sb migration and transformation and revealed the underlying reaction mechanisms,contributing to a better understanding of the geochemical dynamics of Sb.

关键词： Antimony Manganese Lepidocrocite Sorption oxidation

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oxidation of antimony (Ⅲ) in soil by manganese (Ⅳ) oxide using X-ray absorption fine structure

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Journal of Environmental Sciences 2018年第11期30卷 31-37页

作者： Lei Fu Katsumi Shozugawa Motoyuki Matsuo Graduate School of Arts and Sciences The University of Tokyo 3-8-1 Komaba Meguro-ku Tokyo 153-8902 Japan

The oxidation of antimony （Ⅲ） in soils was studied using X-ray absorption fine structure （XAFS） spectra. An andosol soft sample and artificial soil samples （SiO2 blended with iron （Ⅲ） hydroxide and manganese （Ⅳ） oxide） were used herein. After adding antimony （Ⅲ） oxide to all soil samples, the oxidation process was observed by recording the XAFS spectra of Sb K-edge, Fe Kedge, and Mn K-edge. The results indicated that manganese （Ⅳ） oxide played an important role in the oxidation of Sb（Ⅲ）; however iron （Ⅲ） hydroxide was not directly related to the reaction. During a 2-hr continuous Sb K-edge X-ray absorption near edge structure （XANES） measurement with an interval of I rain of one of the artificial soil samples （SiO2 ＋ MnO2 ＋ Sb2O3）, a pseudo-first-order reaction was determined with an average estimated rate of 0.52 ±0.04 hr-1. Compared to the lower oxidation rate of andosol, it is suggested that because of the low concentration of Mn（Ⅳ） in natural soils, the oxidation process of Sb（Ⅲ） might be relatively slow and require more time to convert Sb（Ⅲ） to Sb（V）.

关键词： Soil Antimony oxidation Manganese （Ⅳ） oxide X-ray absorption fine structure （XAFS）

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oxidation behavior of ferritic/martensitic steels in flowing supercritical water

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Journal of Materials Science & Technology 2021年第5期64卷 114-125页

作者： Quanqiang Shi Wei Yan Yanfen Li Naiqiang Zhang Yiyin Shan Ke Yang Hiroaki Abe Key Laboratory of Nuclear Materials and Safety Assessment Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China Key Laboratory of Condition Monitoring and Control for Power Plant Equipment of Ministry of Education North China Electric Power UniversityBeijing 102206China Institute of Metal Research Chinese Academy of SciencesShenyang 110016China School of Engineering The University of TokyoTokaiIbaraki319-1188Japan

The oxidation behavior of two Ferritic/Martensitic(F/M)steels including novel SIMP steel and commercial P91 steel were investigated by exposure to flowing deaerated supercritical water(SCW)at 700℃for up to 1000 h.The kinetic weight gain curves follow parabolic and near-cubic rate equations for SIMP and P91 steels,respectively.X-Ray Diffraction analysis showed the presence of magnetite and a spinel phase in flowing SCW for both steels.The morphology and structure of the oxide scales formed on these two steels were analyzed.The relationship between the microstructure and oxidation behavior and the reason that SIMP steel showed better oxidation resistance than P91 steel were discussed.

关键词： Ferritic/martensitic steel Supercritical water oxidation Oxide scale SIMP steel

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Development of EPDM composites reinforced by CNTs@SiO_(2)for thermal protection systems of aerospace propulsion:Significant improvement in oxidation and ablation resistance properties

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Chinese Journal of Aeronautics 2024年第2期37卷 471-481页

作者： Li WANG Jiang LI Kang LI Yiwei WANG Chenyang MA Science and Technology on Combustion Internal Flow and Thermal-Structure LaboratoryNorthwestern Polytechnical UniversityXi’an 710072China

Carbon Nanotubes(CNTs)reinforced Polymer-Matrix Composites(PMCs)is widely used as insulation materials in thermal protection system of aerospace propulsion.However,CNTs are prone to oxidation and have high thermal conductivities,which makes it difficult to improve the ablation resistance of insulation materials that contain CNTs.SiO_(2)was encapsulated onto the surface of CNTs(CNTs@SiO_(2)),which were then added to Ethylene Propylene Diene Monomer(EPDM)rubber to prepare the insulation materials.Thermogravimetric analysis and ablation test were used to evaluate the resistance of the insulation materials to thermal oxidation and ablation.Additionally,scanning electron microscopy was performed to analyze their microstructures.Results revealed that the addition of CNTs@SiO_(2)could visibly reduce the effects of hot corrosion and ablation on insulation materials.The C-CNTs@SiO_(2)-1 formulation had the best ablative resistance.Further,compared with the unencapsulated formulation(C-CNTs-10),the C-CNTs@SiO_(2)-1 formulation reduced the line ablation rate by 51%to 0.0130 mm/s after oxygen-acetylene experiments.Lastly,the ablation mechanism was investigated based on the effects of the CNTs@SiO_(2)additive on their properties.Thus,the improvement in ablation performance may be attributed to CNTs@SiO_(2)-induced decreases in thermal conductivity,improvement in the hot corrosion resistance in the char layer,and changes in the microstructure.

关键词： Polymer-Matrix Composites(PMCs) Carbon Nanotubes(CNTs) Thermal properties Ablation oxidation

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Durable dual-state duplex Si-HfO_(2)with excellent oxidation and cracking resistance

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Journal of Advanced Ceramics 2024年第3期13卷 388-401页

作者： Lin Chen Jing-Chuan Luo Wen-Qi Yang Chang-Jiu Li Guan-Jun Yang State Key Laboratory for Mechanical Behavior of Materials School of Materials Science and EngineeringXi’an Jiaotong UniversityXi’an 710049China Xi’an Aerospace Engine Company Limited in CASC Xi’an 710065China

The lifetime of Si bond coatings in environmental barrier coatings is constrained by phase-transition-induced cracking of the SiO_(2)scale.In this study,Si-HfO_(2)dual-state duplex composite materials are proposed to address this issue by partially forming HfSiO_(4)and minimizing the SiO_(2)content.The as-prepared composite exhibited a structure comprising discrete HfO_(2)“bricks”embedded in a continuous Si“mortar”,while the oxidized state transformed into discrete HfSiO_(4)“bricks”within continuous thin SiO_(2)“mortars”.The results indicate that continuous thin SiO_(2)contributes to reducing the oxidation rate to a level comparable to that of pure Si,and discrete HfSiO_(4)particles aid in relieving phase transition-induced stress and inhibiting crack propagation,thereby enhancing oxidation and cracking resistance simultaneously.Consequently,the composite with 20 mol%HfO_(2)and a mean particle size of~500 nm at 1370℃exhibited a service lifetime 10 times greater than that of pure Si.This research provides valuable insights for designing Si-based bond coatings with improved service lifetime.

关键词： oxidation environmental barrier coatings(EBCs) phase transition cracking bond coatings

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oxidation behaviors of TA15 titanium alloy and TiBw reinforced TA15 matrix composites prepared by spark plasma sintering

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Journal of Materials Science & Technology 2020年第2期37卷 46-54页

作者： Dongjun Wang Hao Li Wei Zheng National Key Laboratory for Precision Hot Processing of Metals Harbin Institute of TechnologyHarbin 150001China School of Materials Science and Engineering Harbin Institute of TechnologyHarbin 150001China Xi’an Space Engine Company Limited Xi’an710100China

The purpose of this study is to investigate the oxidation behaviors of the TA15 titanium alloy and TiBw/TA15 composite with network microstructure in the temperature range of 873–1073 K.The results show that the oxidation kinetics of the TA15 titanium alloy and TiBw/TA15 composite follows different laws at various oxidation temperatures.Moreover,the effective activation energy Q for oxidation of the TA15 titanium alloy and TiBw/TA15 composite is determined to be 299±19.9 kJ/mol and 339±8.31 kJ/mol at the temperature of 973–1073 K,respectively.The experimental achievements of oxidation kinetics and oxide scales formed in the test temperatures indicate that the TiBw/TA15 composite exhibits a higher oxidation resistance than TA15 titanium alloy.A schematic diagram of oxidation mechanism is established to further reveal the oxidation process for TiBw/TA15 composite at elevated temperatures.

关键词： Composite materials Powder metallurgy Sintering Kinetics oxidation

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