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ZG42 CrMo缩松区疲劳裂纹的偏析和微裂纹的形成

赵芳欣 , 张瑛洁 , 张松 , 赵祖欣 , 尹绍奎 , 李德成

金属学报

测定了ZG42CrMo高周疲劳裂纹扩展速率,对疲劳裂纹扩展过程进行了金相追踪观察.用EPM研究了缩松及其表面微裂纹和硫化物的形态.用TEM研究了裂纹顶端位错组态和滑移特征.讨论了缩松对裂纹捕获和偏折对疲劳裂纹扩展的双重影响及微裂纹萌生的可能机制.

关键词: ZG42CrMo , porosity , fatigue crack deflection , microcrack.

Zn-Fe-SiO2复合镀层的性能研究

范云鹰 , 张英杰 , 陈阵 , 董鹏 , 罗少林

中国腐蚀与防护学报

分别采用硫酸盐体系和氯化物体系的最佳工艺条件电沉积制备了高铁(Fe mass%>1%)和低铁(Fe mass%<1%)的Zn-Fe-SiO2复合镀层,并系统测试了不同厚度Zn-Fe-SiO2复合镀层的耐蚀性、结合力、孔隙率和氢脆性等综合性能,同时与电镀Zn及Zn-Fe合金进行了对比.实验结果表明:Zn-Fe-SiO2复合镀层的耐蚀性及其它综合性能均优于Zn-Fe合金镀层和Zn镀层.因此,相对于电镀Zn及Zn-Fe合金,电沉积Zn-Fe-SiO2复合镀层技术具有先进性,应用前景良好.

关键词: 复合镀层 , , corrosion resistance , adhesive , porosity

新型塑性加工制备球形孔多孔金属及其性能

施国栋何德坪何思渊丁龙

材料研究学报

将铝板塑性加工成半球孔层金属结构薄层, 以此为基本单元按一定方式连接形成球形孔多孔金属, 研究了孔结构对球形孔多孔金属性能的影响. 结果表明, 平板层相连的球形孔结构, 使其强度高于同样条件下堆积的空心金属球结构. 这种新型球形孔多孔金属的强度较高, 能够有效地吸收能量, 铝板的厚度和孔隙率对其压缩和能量吸能性能有明显的影响.

关键词: 金属材料 , punch , porous metal , porosity , compression and energy absorption , spherical pore

反应烧结法制备高强度多孔氮化硅陶瓷

姚冬旭 , 曾宇平

无机材料学报 doi:10.3724/SP.J.1077.2011.00422

以硅粉(Si)为起始原料, 氧化钇(Y2O3)为烧结助剂, 利用干压成型工艺制备出不同气孔率的多孔硅坯体, 通过反应烧结得到高强度多孔氮化硅(Si3N4)陶瓷. 研究了Y2O3添加量在不同升温制度下对于氮化率的影响, 以及1500~1750℃后烧结对多孔材料强度的影响. 结果表明: 添加9%Y2O3的样品具有较高的氮化率, 主要是Y2O3与Si粉表面的SiO2在较低的温度下反应生成了Y5Si3O12N. 在不同的反应条件下可得到气孔率为30%~50%, 强度为160~50MPa的样品. 在1750、 0.5MPaN2气压下对样品进行后处理, α-Si3N4完全转变成柱状β-Si3N4, 晶型转变有利于强度提高,气孔率为46%的多孔Si3N4其强度可达140MPa.

关键词: 反应烧结 , porous silicon nitride , flexural strength , porosity

Porous Cube-like In2O3 Nanoparticles and Their Sensing Characteristics toward Ethanol

Chih-Chia HUANG , Chen-Sheng YEH

材料科学技术(英文)

Porous cube-like crystalline In2O3 nanoparticles with an average diagonal length of 34.8 nm were fabricated by a laser ablation-reflux process to form In(OH)3, followed by a calcination treatment to yield porous In2O3. HRTEM (high-resolution transmission electronic microscopy), XRD (X-ray diffraction), BET (Brunauer-Emmett-Teller), and XPS (X-ray photoelectron spectroscopy) analysis were used to characterize their crystalline structures, grain sizes, surface areas, and surface compositions. The as-prepared porous indium oxides were tested for their sensing properties toward ethanol. Non-porous In2O3 nanopowder (about 40 nm) was also examined in order to compare the results with the as-prepared porous In2O3 nanomaterials. The porous In2O3 exhibited much better performance than that of non-porosus In2O3, and showed enhanced sensitivity with a lower detection limit than other reported In2O3-based materials when exposed to ethanol. Good gas sensitivity and linear behavior as a function of ethanol concentration were observed in the porous In2O3 nanoparticles.

关键词: In2O3 , porosity , nanoparticles , gas , senso

FACTORS INFLUENCING THE WEAR BEHAVIOR OF PM STEELS

J.A. Wang

金属学报(英文版)

A review was made on the research progress of wear behavior of PM steels in recentyears. Wear is not an intrinsic property of PM steels, which is strongly influencedby the wear test conditions. However, many other factors that determine the me-chanical properties of PM steels also affect the wear behavior. Porosity has differenteffects on the wear of PM steels depending on the application conditions. Under drysliding condition, higher porosity results in lower wear resistance. The influence ofmicrostructures on wear resistance was in the order: carbide, martensite, bainite andlamellar pearlite. The wear resistance increases with hardness, but this relationshipchanges with the porosity and microstructures of PM steels.``

关键词: wear , null , null , null , null

Novel Reduced-friction Materials by Laser Cladding of Copper Alloy on Cast Iron

Xichen YANG Milin ZHONG Tianxi ZHENG Naikun ZHANG Laser Processing Lab. , Tianjin Institute of Textile Science and Technology , Tianjin , 300160 , China

材料科学技术(英文)

Copper alloys suitable for laser cladding on cast iron are selected trom rune types of conventional powders. There are a poor spreading ability and porosity of copper alloy over the surface of castiron. Copper alloy surface is easily oxidized in atmosphere. These shortages have been overcome by ad- ding deoxidizers of Si and H_3BO_3. Laser parameters, stress and coefficient of friction have been ex- amined, and the larger smooth surface of Cu/cast iron for friction by laser cladding has been made for the application of the guide shoes of machine.

关键词: laser cladding , null , null

机械镀锌中强化时间对锌镀层性能的影响

苑振涛 , 彭增华 , 王胜民 , 赵晓军 , 何明奕

材料保护

为了掌握机械镀锌中强化时间对镀锌层的影响,分别设置了4种机械镀锌的强化时间(0,5,15,60 min),制备了4种镀层.采用体视显微镜、表面洛氏硬度计研究了强化时间对锌镀层平整度、硬度的影响,采用重量法和铁试剂法分析了强化时间对锌镀层致密度和孔隙率的影响,采用XRD技术研究了强化时间对锌镀层物相组成的影响,采用中性盐雾试验研究了强化时间对锌镀层耐腐蚀性的影响.结果表明:在机械镀锌中随着强化时间的增加,锌镀层的平整度、致密度有所提高,硬度有所增加;强化时间对锌镀层的孔隙率、物相组成和耐蚀性没有影响.

关键词: 机械镀锌 , 强化时间 , 镀锌层 , 平整度 , 致密度 , 硬度 , 孔隙率 , 物相组成 , 耐蚀性

高频开关电源纹波系数对电镀硬铬质量的影响

王庆浩 , 梁汝华

电镀与涂饰

研究了普通直流高频开关电源(纹波系数>60%)加装滤波器后对电镀硬铬质量的影响.结果表明,加装滤波器使电源的纹波系数降至低于3%后,镀液的深镀能力、均镀能力以及镀层的微裂纹分布、耐磨性能等方面有一定提高,镀层孔隙率大幅降低,镀层显微硬度、光亮度以及电流效率则基本与没有加装滤波器时保持一致,但高区烧焦的程度得到降低.

关键词: 镀硬铬 , 直流电源 , 纹波 , 显微硬度 , 耐磨性 , 裂纹 , 孔隙率

钢铁件上薄层亮镍的孔隙及其封闭试验

袁诗璞

电镀与涂饰

阐述了亮镍镀层孔隙率的危害及影响因素(包括镀层厚度,基体缺陷和粗糙度,待镀表面的洁净度,以及镀液的维护).介绍了降低亮镍镀层孔隙率的主要措施.针对钢铁件上镀薄层亮镍高孔隙率的问题,测试了几种水基缓蚀剂及水溶性清漆的封闭效果,但结果令人失望.采用水溶性蜡封闭剂的效果则较好.

关键词: 钢铁 , 镀亮镍 , 孔隙率 , 封闭 , 缓蚀剂 , 清漆 ,

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