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Structure,mechanical and thermal properties of Y-doped CrAlN coatings 被引量:3
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作者 Jin-lian TIAN Chun HU +2 位作者 Li CHEN Yu-min LOU Ning-ning ZHAO 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2021年第9期2740-2749,共10页
CrAlYN coatings with different Y contents(0,5 and 12 at.%)were deposited by cathodic arc evaporation to investigate the influence of Y-addition on the structure,mechanical and thermal properties of CrAlN coatings by u... CrAlYN coatings with different Y contents(0,5 and 12 at.%)were deposited by cathodic arc evaporation to investigate the influence of Y-addition on the structure,mechanical and thermal properties of CrAlN coatings by using X-ray diffraction,scanning electron microscopy,differential scanning calorimetry,thermal gravimetric analysis and nanoindentation.The structural transformation of single phase cubic Cr_(0.42)Al_(0.58)N and Cr_(0.39)Al_(0.56)Y_(0.05)N coatings to cubic−wurtzite mixed Cr_(0.32)Al_(0.56)Y_(0.12)N coating leads to a drop in hardness from(30.2±0.7)GPa of Cr_(0.42)Al_(0.58)N and(32.0±1.0)GPa of Cr_(0.39)Al_(0.56)Y_(0.05)N to(25.2±0.7)GPa of Cr_(0.32)Al_(0.56)Y_(0.12)N.The incorporation of 5 at.%Y retards the thermal decomposition of CrAlN,verified by the postponed precipitation of w-AlN and N-loss upon annealing.Correspondingly,Cr_(0.39)Al_(0.56)Y_(0.05)N coating consistently exhibits the highest hardness value during thermal annealing.Nevertheless,alloying with Y exerts an adverse effect on the oxidation resistance of CrAlN. 展开更多
关键词 CrAlYN coatings cathodic arc evaporation structural evolution HARDNESS thermal stability oxidation resistance
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Temperature field evolution and heat transfer during continual local induction cladding 被引量:3
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作者 LIU Si-yu QIN Xun-peng +1 位作者 ZHANG Jin-peng ZHAN Jun 《Journal of Central South University》 SCIE EI CAS CSCD 2020年第5期1572-1586,共15页
The evolution of temperature field of the continual motion induction cladding and the depth of heat affected zone are studied in this study.A three-dimensional finite element model for the point type continual inducti... The evolution of temperature field of the continual motion induction cladding and the depth of heat affected zone are studied in this study.A three-dimensional finite element model for the point type continual induction cladding is established to investigate temperature distributions of fixed and motion induction cladding modes.The novel inductor is designed for cladding of curved surfaces.The modeling reliability is verified by the temperature measurements.The influence of process parameters on the maximum temperature and the generation and transfer of heat are studied.Quantitative calculation is performed to its melting rate to verify the temperature distribution and microstructures.The results show that a good metallurgical bond can be formed between the cladding layer and substrate.The melting rate gradually falls from the top of the cladding layer to the substrate,and the grain size in the substrate gradually rises.The heat affected zone is relatively small compared to integral heating. 展开更多
关键词 profile repair induction cladding continual motion temperature field evolution heat transfer
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Microstructure, hardness evolution and thermal stability of binary Al-7Mg alloy processed by ECAP with intermediate annealing 被引量:8
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作者 查敏 李彦军 +2 位作者 Ragnvald MATHIESEN Ruben BJRGE Hans J. ROVEN 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2014年第7期2301-2306,共6页
A binary Al-7Mg alloy was processed by equal channel angular pressing (ECAP) at room temperature via route Bc, combined with intermediate annealing. After 6 passes, a high hardness of HV218 is achieved. Transmission... A binary Al-7Mg alloy was processed by equal channel angular pressing (ECAP) at room temperature via route Bc, combined with intermediate annealing. After 6 passes, a high hardness of HV218 is achieved. Transmission electron microscopy (TEM) observations demonstrate that ECAP leads to a significant grain refinement and ultrafine grains down to 100-200 nm are developed after 5 or 6 passes. X-ray diffraction (XRD) analysis indicates that the major part of Mg atoms are in solid solution in the deformed material, and the possible strengthening effect of Mg solute atom clusters or precipitates is neglected. The high hardness of the 6 pass-treated materials comes mainly from grain boundary strengthening, which contributes about 41% to the total strength, while dislocations and Mg solid solution contribute about 24% and 35% to the remaining strength, respectively. Also, the thermal stability of this severely deformed material was investigated by hardness measurements. The material is relatively stable when annealed at a temperature lower than 250 ℃, while annealing at 300 ℃ leads to a rapid softening of the material. 展开更多
关键词 Al-Mg alloys equal channel angular pressing (ECAP) as-deformed microstructure hardness evolution strengthening thermal stability
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重大疫情中网络舆情危机演变及治理策略 被引量:13
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作者 郭宝盛 季红颖 《情报科学》 CSSCI 北大核心 2020年第6期103-109,138,共8页
【目的/意义】通过对重大疫情中的网络舆情危机进行深入分析和研究,为提升我国应对重大疫情危机、构建清爽的网络空间、维护社会稳定找到出发点和着力点。【方法/过程】通过构建网络舆情传导链和网络舆情危机演变结构,阐述了重大疫情应... 【目的/意义】通过对重大疫情中的网络舆情危机进行深入分析和研究,为提升我国应对重大疫情危机、构建清爽的网络空间、维护社会稳定找到出发点和着力点。【方法/过程】通过构建网络舆情传导链和网络舆情危机演变结构,阐述了重大疫情应对中的网络舆情危机演变的各个阶段形成及运行机理,在梳理其特殊表征和对典型案例回顾分析基础上,提出了治理重大疫情网络舆情危机的主要策略。【结果/结论】要从强化政府公信力度、加强网络媒体管控、引导网民文明用网、防范危机叠加风险、消解国际舆情压力五个方面进行有效治理。 展开更多
关键词 重大疫情 网络舆情 危机传导 演变热度
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