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Tribology of WC reinforced SiC ceramics:Influence of counterbody
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作者 Sandan Kumar SHARMA B.Venkata MANOJ KUMAR Young-Wook KIM 《摩擦(英文版)》 CSCD 2019年第2期129-142,共14页
Hot pressed silicon carbide(SiC) composites prepared with 0,10,30 or 50 wt% tungsten carbide(WC) are subjected to dry sliding wear against WC-Co and steel ball.In particular an attempt has been made to answer the foll... Hot pressed silicon carbide(SiC) composites prepared with 0,10,30 or 50 wt% tungsten carbide(WC) are subjected to dry sliding wear against WC-Co and steel ball.In particular an attempt has been made to answer the following important questions:(i) How does the load(from 5 to 20 N) effect sliding wear behaviour of SiC-ceramics against WC-Co and steel counterbodies?(ii) Is there any effect of WC content on friction and wear characteristics of SiC ceramics?(iii) Does the dominant material removal mechanism of SiC ceramics change with the addition of WC or counterbody?(iv) What is the influence of mechanical properties on the sliding wear? Experimental results indicated that coefficient of friction(COF) for the SiC ceramics varied between 0.66 and 0.33 with change in load and counterbodies.Wear volume for SiC ceramics found approximately 6-10 times more against WC-Co as compared against steel.Wear volume changes from 2.0 × 10^–3mm^3 to 1.2 × 10^–2mm^3 with change in counterbodies for SiC -(10,30 or 50 wt%) WC composite at 20 N.SiC ceramics indicated abrasion and composites reveal tribochemical wear as major material removal mechanisms.Wear is influenced by the hardness of counterbody and fracture toughness of SiC -WC composites. 展开更多
关键词 silicon CARBIDE TUNGSTEN CARBIDE composites steel SLIDING WEAR counterbody
Thermally annealed gamma irradiated Ni/4H-SiC Schottky barrier diode characteristics 预览
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作者 P.Vigneshwara Raja N.V.L.Narasimha Murty 《半导体学报:英文版》 EI CAS CSCD 2019年第2期57-63,共7页
Thermal annealing effects on gamma irradiated Ni/4 H-SiC Schottky barrier diode(SBD) characteristics are analyzed over a wide range of temperatures(400–1100 °C). The annealing induced variations in the concentra... Thermal annealing effects on gamma irradiated Ni/4 H-SiC Schottky barrier diode(SBD) characteristics are analyzed over a wide range of temperatures(400–1100 °C). The annealing induced variations in the concentration of deep level traps in the SBDs are identified by thermally stimulated capacitance(TSCAP). A little decrease in the trap density at E_C – 0.63 eV and E_C –1.13 eV is observed up to the annealing temperature of 600 °C. Whereas, a gamma induced trap at E_C – 0.89 eV disappeared after annealing at 500 °C, revealing that its concentration(< 1013 cm-3) is reduced below the detection limit of the TSCAP technique.The electrical characteristics of irradiated SBDs are considerably changed at each annealing temperature. To understand the anomalous variations in the post-annealing characteristics, the interface state density distribution in the annealed SBDs is extracted.The electrical properties are improved at 400 °C due to the reduction in the interface trap density. However, from 500 °C, the electrical parameters are found to degrade with the annealing temperature because of the increase in the interface trap density.From the results, it is noted that the rectifying nature of the SBDs vanishes at or above 800 °C. 展开更多
关键词 4H-silicon CARBIDE Schottky barrier diode thermal ANNEALING electrically active defects thermally stimulated CAPACITANCE
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Corrosion behavior of Ni-based coating containing spherical tungsten carbides in hydrochloric acid solution
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作者 Shan-shan Liu Hai-yan Chen +3 位作者 Xuan Zhao Li Fan Xiao-ming Guo Yan-sheng Yin 《钢铁研究学报:英文版》 SCIE EI CAS CSCD 2019年第2期191-199,共9页
A Ni-based alloy coating with 30 wt.%spherical fungsten carbide particles was prepared through plasma transferred arc welding on 42CrMo steel.The composition and microstructure of the coati ng were examined through X-... A Ni-based alloy coating with 30 wt.%spherical fungsten carbide particles was prepared through plasma transferred arc welding on 42CrMo steel.The composition and microstructure of the coati ng were examined through X-ray diffraction and scanning electron microscopy with energy-dispersive spectrometry.The corrosion behaviors of the coating compared to the Ni coating without tungsten carbide particles and to the bare substrate in a0.5 mol/L HC1 solution were presented through polarization curves,electrochemical impedance spectroscopy(EIS)measurements and long-term immersion tests.The results demonstrated that the composite coating microstructure comprised Ni matrix,Ni-rich phase,tungsten carbide particles,W-rich phase and Cr-rich phase.The polarization curves and EIS measurements presented that a passivation film,which mainly included Ni,Cr,Fe and W oxides,was formed in the composite coating that protected the substrate from corrosion by HC1 solution.In the immersion tests,a micro-galvanic reaction at the new-formed phases and Ni matrix interface caused severe pit corrosion and Ni matrix consumption.The debonding of Ni-rich and W-rich phases could be observed with the immersion time extension.The tungsten carbide particles and Cr-rich phase were still attached on the surface for up to 30 days. 展开更多
关键词 Plasma TRANSFERRED welding SPHERICAL TUNGSTEN CARBIDE NI-BASED coating Corrosion resistance Electrochemical impedanee spectroscopy
新型渣浆泵用材料的腐蚀性能研究 预览
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作者 谭騛 宁兆祥 +2 位作者 许晓嫦 任鹏禾 陈广兴 《材料导报》 EI CAS CSCD 北大核心 2019年第24期4157-4163,共7页
针对渣浆泵用耐磨蚀材料在服役过程中由于腐蚀严重导致使用寿命缩短的问题,研发了一种新型耐磨蚀材料(A合金)。采用金相显微镜、X射线衍射仪、全浸腐蚀、扫描电镜、极化曲线、阻抗谱、X射线光电子能谱对材料在模拟服役环境腐蚀液中的腐... 针对渣浆泵用耐磨蚀材料在服役过程中由于腐蚀严重导致使用寿命缩短的问题,研发了一种新型耐磨蚀材料(A合金)。采用金相显微镜、X射线衍射仪、全浸腐蚀、扫描电镜、极化曲线、阻抗谱、X射线光电子能谱对材料在模拟服役环境腐蚀液中的腐蚀速率、腐蚀特征、电化学特性以及钝化膜组成进行了分析。将A合金与SUS316L不锈钢、KMTBCr26高铬铸铁进行对比分析,结果表明:A合金的显微组织是由高铬的奥氏体基体以及高硬度的M23C6型碳化物组成,这种碳化物类型使得材料具有优异的耐腐蚀性能。在室温条件下腐蚀192h,A合金、SUS316L、KMTBCr26的腐蚀速率分别为0.0197mm/y、0.322mm/y、26.0396mm/y。A合金表面出现少量点蚀坑,而SUS316L和KMTBCr26材料表面发生局部腐蚀甚至全面腐蚀。A合金基体在析出碳化物后Cr含量没有出现贫化,降低了相与基体之间的腐蚀电位差;材料中富含的Cu元素使得表面钝化膜的稳定性提高。在电化学腐蚀过程中,A合金的自腐蚀电位最高、腐蚀电流密度最小、阻抗谱容抗弧半径最大、腐蚀倾向最小、表面形成的钝化膜稳定性最强,钝化膜的组成为Fe2O3、Cr2O3以及部分Cu氧化物。 展开更多
关键词 耐磨耐蚀铸钢 碳化物 点蚀 极化曲线 阻抗谱
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压铸模具钢4Cr5Mo2V的组织和碳化物的高温行为
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作者 林鹏 孙立国 +2 位作者 马党参 周健 迟宏宵 《钢铁研究学报》 CAS CSCD 北大核心 2019年第8期762-769,共8页
通过测定4Cr5Mo2V钢在不同冷却速度下的相变膨胀曲线,得到其过冷奥氏体连续冷却转变曲线(CCT曲线)及Ac1、Ac3和Ms点温度。结合各相变点和Thermal-Calc分析结果,利用原位观察研究了4Cr5Mo2V钢在升温、保温和降温过程中的组织和及升温过... 通过测定4Cr5Mo2V钢在不同冷却速度下的相变膨胀曲线,得到其过冷奥氏体连续冷却转变曲线(CCT曲线)及Ac1、Ac3和Ms点温度。结合各相变点和Thermal-Calc分析结果,利用原位观察研究了4Cr5Mo2V钢在升温、保温和降温过程中的组织和及升温过程中碳化物的变化规律。结果表明,4Cr5Mo2V钢的相变点温度分别是:Ac1为820℃,Ac3为855℃,Ms为275℃;升温过程中,Cr23C6先于VC溶解,并在表面产生浮凸和空洞;保温过程中,晶粒长大机制为旧晶界迁移,并使得晶粒发生吞并和长大;连续冷却过程中,4Cr5Mo2V钢马氏体形的生成是以先形成的板条为基准逐步形成彼此平行的板条而构成板条束,或者是先形成的板条可以触发产生另一方向(60°或120°)的板条马氏体,构成多边形等具有几何形状的组织特征。 展开更多
关键词 4Cr5Mo2V钢 组织 碳化物 高温行为
高性能搓丝板HYSP19的开发 预览
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作者 尤晓东 邵青立 +2 位作者 朱长青 郝世风 李栋 《河北冶金》 2019年第4期53-55,共3页
研究开发了一种高性能搓丝板新材料HYSP19,材料的成分设计遵循含Co、低W、低V、高Mo的设计原则,生产采用独特的专有工艺流程。经使用检验,宽度150~250mm规格搓丝板坯的横截面中心部位碳化物不均匀度≤4.0级,使用过程质量稳定,使用寿命达... 研究开发了一种高性能搓丝板新材料HYSP19,材料的成分设计遵循含Co、低W、低V、高Mo的设计原则,生产采用独特的专有工艺流程。经使用检验,宽度150~250mm规格搓丝板坯的横截面中心部位碳化物不均匀度≤4.0级,使用过程质量稳定,使用寿命达到15万次,满足高档搓丝板的材料要求,基本达到进口材料水平。 展开更多
关键词 搓丝板 HYSP19 碳化物 不均匀度 硬度
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深冷处理对低碳高合金马氏体轴承钢力学性能及组织的影响
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作者 李东辉 李志敏 +3 位作者 肖茂果 李绍宏 赵昆渝 杨卯生 《材料研究学报》 EI CAS CSCD 北大核心 2019年第8期561-571,共11页
利用洛氏硬度计、X射线衍射仪、扫描电子显微镜及透射电子显微镜等研究了低碳高合金马氏体轴承钢深冷处理后的硬度变化及组织演化。结果表明:深冷处理促使部分残留奥氏体转变为马氏体,导致深冷处理后实验钢的硬度较淬火态硬度有所升高... 利用洛氏硬度计、X射线衍射仪、扫描电子显微镜及透射电子显微镜等研究了低碳高合金马氏体轴承钢深冷处理后的硬度变化及组织演化。结果表明:深冷处理促使部分残留奥氏体转变为马氏体,导致深冷处理后实验钢的硬度较淬火态硬度有所升高。经深冷处理后实验钢在0~100 h回火过程中的硬度均比未深冷处理实验钢的硬度高。深冷处理促使钢中碳原子偏聚并在回火过程中以碳化物的形式析出,与未经深冷处理的实验钢相比,经深冷处理的实验钢回火后马氏体基体中的含碳量更低,表明实验钢经深冷处理后在回火过程中析出更多的碳化物。透射电镜分析表明,实验钢在回火过程中析出的大量弥散分布的纳米级M2C和M6C型碳化物是实验钢长时间回火后保持高硬度的主要原因。 展开更多
关键词 金属材料 高合金钢 深冷处理 碳化物 残留奥氏体
金刚石表面改性单金属镀层的研究进展
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作者 温国栋 《热加工工艺》 北大核心 2019年第16期18-21,共4页
在查阅国内外相关文献资料的基础上,综述了金刚石表面碳化物形成元素单金属镀层以及金刚石表面碳化物形成元素的镀覆方法及其发展情况,可为金刚石表面改性的研究和应用提供参考。
关键词 金刚石 碳化物 单金属镀层
Design and fabrication of 10-kV silicon–carbide p-channel IGBTs with hexagonal cells and step space modulated junction termination extension
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作者 温正欣 张峰 +8 位作者 申占伟 陈俊 何亚伟 闫果果 刘兴昉 赵万顺 王雷 孙国胜 曾一平 《中国物理B:英文版》 SCIE EI CAS CSCD 2019年第6期472-476,共5页
10-kV 4 H–SiC p-channel insulated gate bipolar transistors(IGBTs) are designed, fabricated, and characterized in this paper. The IGBTs have an active area of 2.25 mm~2 with a die size of 3 mm× 3 mm. A step space... 10-kV 4 H–SiC p-channel insulated gate bipolar transistors(IGBTs) are designed, fabricated, and characterized in this paper. The IGBTs have an active area of 2.25 mm~2 with a die size of 3 mm× 3 mm. A step space modulated junction termination extension(SSM-JTE) structure is introduced and fabricated to improve the blocking performance of the IGBTs.The SiC p-channel IGBTs with SSM-JTE termination exhibit a leakage current of only 50 nA at-10 kV. To improve the on-state characteristics of SiC IGBTs, the hexagonal cell(H-cell) structure is designed and compared with the conventional interdigital cell(I-cell) structure. At an on-state current of 50 A/cm~2, the voltage drops of I-cell IGBT and H-cell IGBT are10.1 V and 8.3 V respectively. Meanwhile, on the assumption that the package power density is 300 W/cm~2, the maximum permissible current densities of the I-cell IGBT and H-cell IGBT are determined to be 34.2 A/cm~2 and 38.9 A/cm~2 with forward voltage drops of 8.8 V and 7.8 V, respectively. The differential specific on-resistance of I-cell structure and H-cell structure IGBT are 72.36 m?·cm~2 and 56.92 m?·cm~2, respectively. These results demonstrate that H-cell structure silicon carbide IGBT with SSM-JTE is a promising candidate for high power applications. 展开更多
关键词 SILICON CARBIDE power device insulated gate bipolar transistors(IGBTs) high voltage
金属材料深冷处理技术研究进展
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作者 李佐政 牛显明 +1 位作者 刘文朝 刘大娇 《热加工工艺》 北大核心 2019年第10期42-46,共5页
深冷处理作为一种有效提高材料性能的工艺,其研究已经从黑色金属领域走向有色金属。综合现有文献,总结了金属材料及其合金深冷处理的研究进展,简述了深冷处理技术的工艺和机理,并结合国内外研究现状提出了一些展望。
关键词 深冷处理 奥氏体 马氏体 碳化物
Porous SiC Prepared Using Fine α-Al2O3 and SiC Powders as Sintering Additives 预览
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作者 LIU Jiadong PENG Zhijian +2 位作者 LIU Qingzhu SUN Guangchao LIU Kaiqi 《中国耐火材料:英文版》 CAS 2019年第2期31-36,共6页
A reaction bonding technique and a method of layer coating were developed to fabricate porous SiC.The green body was prepared using 250.0μm SiC particles as the raw material,fineα-Al2O3 and SiC powders with mass rat... A reaction bonding technique and a method of layer coating were developed to fabricate porous SiC.The green body was prepared using 250.0μm SiC particles as the raw material,fineα-Al2O3 and SiC powders with mass ratio of 2.5:1as sintering additives,65.2μm graphite as the pore-forming agent and polyvinyl alcohol(PVA)as the binder.The micro powders were coated on the surface of coarse SiC particles.After sintering,fine SiC particles were oxidized to silica(SiO2)then transforming into cristobalite,which finally reacted withα-Al2O3 to produce mullite(3Al2O3·2SiO2).The results show that SiC particles are bonded by the mullite and oxidation-derived SiO2.The apparent porosity of the specimens decreases from 31.3%to 20.5%with the amount of micro powders increasing from 5 mass%to 20 mass%.The bending strength increases at the first stage and then decreases with the increase of fine powders,and the specimen with 10 mass%of fine powders shows relatively high bending strength of 23.5 MPa. 展开更多
关键词 porous silicon CARBIDE POWDERS reaction BONDING POROSITY BENDING strength
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Neutronic analysis of silicon carbide cladding accident-tolerant fuel assemblies in pressurized water reactors 预览
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作者 Zhi-Xiong Tan Jie-Jin Cai 《核技术:英文版》 SCIE CAS CSCD 2019年第3期105-113,共9页
In resonance with the Fukushima Daiichi Nuclear Power Plant accident lesson, a novel fuel design to enhance safety regarding severe accident scenarios has become increasingly appreciated in the nuclear power industry.... In resonance with the Fukushima Daiichi Nuclear Power Plant accident lesson, a novel fuel design to enhance safety regarding severe accident scenarios has become increasingly appreciated in the nuclear power industry. This research focuses on analysis of the neutronic properties of a silicon carbide (SiC) cladding fuel assembly, which provides a greater safety margin as a type of accident-tolerant fuel for pressurized water reactors. The general physical performance of SiC cladding is explored to ascertain its neutronic performance. The neutron spectrum, accumulation of 239Pu, physical characteristics, temperature reactivity coefficient, and power distribution are analyzed. Furthermore, the influences of a burnable poison rod and enrichment are explored. SiC cladding assemblies show a softer neutron spectrum and flatter power distribution than conventional Zr alloy cladding fuel assemblies. Lower enrichment fuel is required when SiC cladding is adopted. However, the positive reactivity coefficient associated with the SiC material remains to be offset. The results reveal that SiC cladding assemblies show broad agreement with the neutronic performance of conventional Zr alloy cladding fuel. In the meantime, its unique physical characteristics can lead to improved safety and economy. 展开更多
关键词 Accident-tolerant fuels Silicon CARBIDE CLADDING NEUTRONIC characteristics Pressurized water REACTOR
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回火时间对07MnNiMoDR钢板组织和性能的影响 预览
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作者 刘立县 王东阳 +2 位作者 王建国 邸熹 管秀兵 《宽厚板》 2019年第4期15-16,共2页
通过07MnNiMoDR钢板不同时间回火试验,对拉伸和冲击性能进行对比分析,结果表明:随着回火时间延长,钢的强度有所降低,冲击韧性出现单值低的现象。随着回火时间的增加,显微组织中的碳化物分布趋于均匀化,且存在晶界集聚现象。
关键词 回火时间 冲击韧性 显微组织 碳化物
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Hybrid Ti2AlC Bonded Diamond Composites Prepared by a Self-propagation Sintering Approach
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作者 张旺玺 LIANG Baoyan +1 位作者 LUO Wei WANG Yanzhi 《武汉理工大学学报:材料科学英文版》 SCIE EI CAS 2019年第1期82-85,共4页
Ti, Al, graphite and diamond powders were used as raw materials to prepare Ti2AlC matrixbonded diamond composite using self-propagating high-temperature synthesis(SHS) method. The effect of diamond size and content on... Ti, Al, graphite and diamond powders were used as raw materials to prepare Ti2AlC matrixbonded diamond composite using self-propagating high-temperature synthesis(SHS) method. The effect of diamond size and content on the fabrication of Ti2AlC-bonded diamond material was investigated. Results showed that Ti2AlC matrix-bonded diamond composites could be obtained by SHS. The phase composition and microstructure of the Ti2AlC-bonded diamond material were influenced by the diamond content and size. When the diamond(93 μm) additive amounts were 10% and 20%, the product phases included Ti2AlC, TiC and Al3Ti. However, excess Ti and Al persisted in the sample that contained 30% diamond. Diamond bonded well with the matrix in the sample that contained 10% diamond. Moreover, addition of coarse diamond particles with sizes of 93 and 125 μm produced a mainly Ti2AlC matrix. However, diamond adequately reacted with Ti to form TiC when finer diamond particles(5 and 10 μm) were used. 展开更多
关键词 TITANIUM aluminum CARBIDE DIAMOND content size self-propagation high temperature SINTERING
热处理工艺对AISI 4140钢组织和性能的影响(英文)
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作者 张留军 宋肖阳 +4 位作者 刘玉庆 张心金 朱琳 何毅 董治中 《材料热处理学报》 EI CAS CSCD 北大核心 2019年第4期76-83,共8页
采用光学显微镜(OM)和扫描电镜(SEM)研究了不同正火和回火温度下改性AISI 4140钢的显微组织,采用透射电镜(TEM)和选区电子衍射(SAED)观察分析了其碳化物的类型、尺寸和形态,还对改性AISI 4140钢的硬度、拉伸性能、冲击韧性进行了测试。... 采用光学显微镜(OM)和扫描电镜(SEM)研究了不同正火和回火温度下改性AISI 4140钢的显微组织,采用透射电镜(TEM)和选区电子衍射(SAED)观察分析了其碳化物的类型、尺寸和形态,还对改性AISI 4140钢的硬度、拉伸性能、冲击韧性进行了测试。结果表明:在850~900℃的正火处理过程中,随着正火温度的升高,平均晶粒尺寸保持在14μm左右;当正火温度达到925℃时,平均晶粒尺寸达到20μm以上,导致力学性能下降;马氏体硬度随正火温度的升高先升高后下降,880℃时达到最大值497 HV10;随着回火温度的升高(580~620℃),实验钢中的M3C碳化物变短、变厚,屈服强度从1044 MPa下降到855 MPa,冲击韧性(-18℃)从55 J提高到108 J,这是由于位错密度较低及析出物较多导致的。 展开更多
关键词 AISI 4140钢 碳化物 热处理工艺 显微组织 力学性能
Relation between etching profile and voltage-current shape of sintered SiC etching by atmospheric pressure plasma
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作者 D C SEOK S R YOO +2 位作者 K I LEE Y S CHOI Y H JUNG 《等离子体科学与技术:英文版》 SCIE EI CAS CSCD 2019年第4期137-144,共8页
Sintered silicon carbide(SiC)was etched by a dielectric barrier discharge source.A high voltage bipolar pulse was used with helium gas for the plasma generation.One stable filament plasma was generated and could be us... Sintered silicon carbide(SiC)was etched by a dielectric barrier discharge source.A high voltage bipolar pulse was used with helium gas for the plasma generation.One stable filament plasma was generated and could be used for SiC etching.As the processing gas(NF3)mixing rate increased,the width and depth of the etching profile became narrower and deeper.The differentiated V-Q Lissajous method was used for measuring the capacitances(Ceq)of the electrode after the plasma turned on.The width of the etching profile was proportional to Ceq.As the current peak value/smx of the substrate current in creased,the volume removal rate of SiC increased.The etch depth was proportional to the ratio of/smx to Ceq.Additionally,because of the different characteristics of the plasma disks on SiC substrate by the voltage polarity,the etching profile was unstable.However,in high NF3 mixing process,the etching profile became stable and deeper. 展开更多
关键词 dielectric BARRIER DISCHARGE silicon CARBIDE plasma etching、filament discharge surface CHARGE
DZ1、25CrNiMo和30CrNi3MoV车轴钢的组织与力学性能
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作者 黄文 张艳 +1 位作者 李祥志 斯庭智 《金属热处理》 CAS CSCD 北大核心 2019年第1期112-117,共6页
采用SEM和HRTEM研究了DZ1、25CrNiMo和30CrNi3MoV车轴钢的组织结构,对比分析了3种车轴钢力学性能和组织结构之间的相互关系。结果表明,25CrNiMo和30CrNi3MoV钢的冲击吸收能量(KU2)分别由DZ1钢的80 J提高到103 J和110 J。30CrNi3MoV钢回... 采用SEM和HRTEM研究了DZ1、25CrNiMo和30CrNi3MoV车轴钢的组织结构,对比分析了3种车轴钢力学性能和组织结构之间的相互关系。结果表明,25CrNiMo和30CrNi3MoV钢的冲击吸收能量(KU2)分别由DZ1钢的80 J提高到103 J和110 J。30CrNi3MoV钢回火索氏体组织为细小的碳化物均匀分布在保留了原马氏体板条形态的α-Fe基体上。该组织具有较大的固溶和位错强化,更高的亚界面强化,良好的碳化物第二相强化以及纳米V和Mo合金碳化物(约10 nm)的弥散强化,因此30CrNi3MoV钢抗拉强度(Rm)由DZ1和25CrNiMo钢的600 MPa级显著提高到了1000 MPa级。 展开更多
关键词 车轴钢 力学性能 显微组织 碳化物
Development of gas tungsten arc welding using current pulsing technique to preclude chromium carbide precipitation in aerospace-grade alloy 80A 预览
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作者 P.Subramani M.Manikandan 《矿物冶金与材料学报:英文版》 SCIE EI CAS CSCD 2019年第2期210-221,共12页
Weldments were produced using gas tungsten arc welding(GTAW)and pulsed current gas tungsten arc welding(PCGTAW)techniques with ERNiCr-3 filler wire.Macro examination revealed that the resultant weldments were free fro... Weldments were produced using gas tungsten arc welding(GTAW)and pulsed current gas tungsten arc welding(PCGTAW)techniques with ERNiCr-3 filler wire.Macro examination revealed that the resultant weldments were free from defects.A refined microstructure was observed in the weldment fabricated through PCGTAW.Scanning electron microscopy(SEM)analysis revealed secondary phases in the grain boundaries.Energy-dispersive X-ray spectroscopy(EDS)analysis revealed that microsegregation of Cr carbide precipitates was completely eradicated through PCGTAW.The microsegregation of Nb precipitates was observed in the GTA and PCGTA weldments.X-ray diffraction(XRD)analysis revealed the existence of M23C6 Cr-rich carbide and Ni8Nb phases in the GTA weldments.By contrast,in the PCGTA weldments,the Ni8Nb phase was observed.The Cr2Ti phase was observed in both the GTA and the PCGTA weldments.Tensile tests showed that the strength and ductility of the PCGTA weldments were slightly higher than those of the GTA weldments. 展开更多
关键词 NI-BASED SUPERALLOY welding pulse CURRENT MICROSEGREGATION CHROMIUM CARBIDE
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高活性Ni-Mo2C/ZrO2催化剂干重整甲烷制合成气
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作者 陶青青 黄诗琳 +3 位作者 闫常峰 郭常青 伊立其 赵效勇 《太阳能学报》 EI CAS CSCD 北大核心 2019年第3期831-837,共7页
用浸渍法结合程序升温碳化法制备1Ni-5Mo2C/ZrO2与Mo2C/ZrO2,作为CH4和CO2干重整制合成气反应催化剂。采用X射线衍射(XRD)、BET比表面积(BET)、X显微镜(TEM)对催化剂的结构进行表征,在常压固定床反应器上测试1Ni-5Mo2C/ZrO2与Mo2C/ZrO2... 用浸渍法结合程序升温碳化法制备1Ni-5Mo2C/ZrO2与Mo2C/ZrO2,作为CH4和CO2干重整制合成气反应催化剂。采用X射线衍射(XRD)、BET比表面积(BET)、X显微镜(TEM)对催化剂的结构进行表征,在常压固定床反应器上测试1Ni-5Mo2C/ZrO2与Mo2C/ZrO2催化剂在900℃时(空速为8000 cm3·g^-1cat·h^-1)重整CH4/CO2(CH4∶CO2=1∶1)的催化活性。研究表明,在甲烷干重整(DRM)反应中,催化剂的催化活性在7 h内保持稳定。由于1Ni-5Mo2C/ZrO2催化剂具有合适的孔径,丰富的表面孔以及Ni基载体之间的相互作用,CH4和CO2的转化率均达96%以上,H2和CO现出高催化活性、产率,兼具优良的稳定性能。 展开更多
关键词 合成气 碳化物 甲烷 干重整 稳定性
碳化物析出对CrFeCoNi高熵合金拉伸和腐蚀性能的影响
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作者 崔宇 杜辉 +5 位作者 徐丽萍 刘鹏 蔡嘉洪 卢艳 刘鑫旺 樊自田 《特种铸造及有色合金》 CAS 北大核心 2019年第10期1130-1134,共5页
添加了3%(摩尔分数,下同)的C对CrFeCoNi高熵合金进行合金化,依次进行1 200℃×12h均匀化冷轧800℃×1h再结晶退火,获得了完全再结晶组织,研究了该合金中碳化物的析出特征及其对合金微观组织、室温拉伸性能和腐蚀行为的影响... 添加了3%(摩尔分数,下同)的C对CrFeCoNi高熵合金进行合金化,依次进行1 200℃×12h均匀化冷轧800℃×1h再结晶退火,获得了完全再结晶组织,研究了该合金中碳化物的析出特征及其对合金微观组织、室温拉伸性能和腐蚀行为的影响。结果表明,C合金化后,除了面心立方结构的等轴晶基体之外,还发现了M23C6碳化物随机分布在晶界和晶内。室温屈服强度由CrFe-CoNi合金的386MPa增加到706MPa,但伸长率和耐腐蚀性有所降低。 展开更多
关键词 高熵合金 碳化物 微观组织 拉伸性能 腐蚀行为
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