材料期刊网

Element Analysis of Instrumented Sharp Indentations into Pressure-sensitive Materials

Minh-Quy LE , Seock-Sam KIM

材料科学技术（英文）

Finite element analysis was carried out to investigate the conical indentation response of elastic-plastic solids within the framework of the hydrostatic pressure dependence and the power law strain hardening. A large number of 40 different combinations of elasto-plastic properties with n ranging from 0 to 0.5 and σy/E ranging from 0.0014 to 0.03 were used in the computations. The loading curvature C and the average contact pressure pave were considered within the concept of representative strains and the dimensional analysis. Dimensionless functions associated with these two parameters were formulated for each studied value of the pressure sensitivity. The results for pressure sensitive materials lie between those for Von Mises materials and the elastic model.

关键词: Finite element analysis , null , null , null

Finite Element Analysis of Ceramic Coatings under Spherical Indentation with Metallic Interlayer: Part I Uncracked Coatings

Minh-Quy LE , Seock-Sam KIM

材料科学技术（英文）

Spherical indentation of ceramic coatings with metallic interlayer was performed by means of axisymmetric finite element analysis (FEA). Two typical ceramic coatings with relatively high and low elastic modulus deposited on aluminum alloy and carbon steel were considered. Various combinations of indenter radius-coating thickness ratios and interlayer thickness-coating thickness ratios were used in the modeling. The effects of the interlayer, the coating and the substrate on the indentation behavior, such as the radial stress distribution along the coating surface as well as the coating interface, and the plastic deformation zone evolution in the substrate were investigated in connection with the above mentioned ratios. The coating cracking dominant modes were also discussed within the context of the peak tensile stresses on the coating surface and on the coating interface.

关键词: Finite element analysis , null , null , null

Sliding Wear Behavior of Plasma Sprayed Zirconia Coating on Cast Aluminum against Silicon Carbide Ceramic

Thuong-Hien LE , Young-Hun , Seock-Sam KIM

材料科学技术（英文）

The sliding wear behaviors of ZrO2-22 wt pct MgO (MZ) and ZrO2-8 wt pct Y2O3 (YZ) coatings deposited on a cast aluminum alloy with bond layer (NiCrCoAlY) by plasma spray were investigated under dry test conditions at room temperature. Under all load conditions, the wear mechanisms of the MZ and YZ coatings were almost the same. The material transfer and pullout were involved in the wear process of the studied coatings under the test conditions. The wear rate of the MZ coating was less than that of the YZ coating. While increasing the normal load, the wear rates of the MZ and YZ coatings increased. SEM was used to examine the worn surfaces and to elucidate likely wear mechanisms. Energy dispersive X-ray spectroscopy (EDX) analysis of the worn surfaces indicated that material transfer occurred in the direction from the SiC ball to the disk. Fracture toughness had a significant influence on the wear performance of the coatings. It was suggested that the material transfer played an important role in the wear behavior.

关键词: Plasma spray , null , null , null

Study of Carbon-poor Regions of Austenite during Bainitic Incubation Period by SAM

Xiaolei WU , Husheng JIA , Xiyan ZHANG and Mokuang KANG(Dept. of Materials Science & Engineering , Northwestern Polytechnical University , Xi'an , 710072 , China)(To whom correspondence should be addressed)

材料科学技术（英文）

The variation of carbon composition in undercooled austenite during bainitic incubation period has been investigated in 40CrMnSiMoVA by scanning auger microprobe (SAM). The results show that the outstanding diffusion and redistribution of carbon occur in isothermally reacted specimens. This leads to the formation of carbon-poor regions (CPR) near austenite grain boundaries and in austenite grains. The carbon content in CPR exceeds the equilibrium carbon composition of ferrite. Furthermore, it is indicated that the existence of CPR is thermodynamically possible.

关键词:

SAM AND XPS STUDIES ON SURFACE SEGREGATION OF SUBSTRATE ELEMENTS IN Au-Ni-KOVAR ALLOY SYSTEM

QI Yunxin TANG Wentai XIA Jianguo Nei Mongol Institute of Metallic Materials , Baotou , ChinaLI Wang ZHAN Zhenzong Institute of Physical and Chemical Engineering Research , Tianjin , China

金属学报(英文版)

The surface segregation of substrate elements through the Au layer in the Au-Ni-Kovar sys- tem specimens heated at 250—350℃ for 0.5—1.5 h has been studied by SAM and XPS. Visual evidence of the mechanism for Ni and Co surface segregation of the complicated sys- tem has been given,i.e.Ni and Co penetrated the gold layer mainly by grain boundary diffu- sion and then covered the Au layer by surface diffusion.The strdy results of the chemical states of surface segregation elements not only indicate that oxygen adsorption and oxidation reaction are the driving force for the surface segregation of Ni and Co,but also show that the above segregation can result in water absorption on surfaces.

关键词: Au-Ni-Kovar alloy system , null , null , null , null

Au-Ni-Kovar合金系统基底元素表面偏聚的SAM和XPS研究

齐芸馨 , 唐文泰 , 夏建国 , 李望 , 展振宗

金属学报

本文采用SAM和XPS对实用Au-Ni-Kovar合金系统热处理样品(250—350℃,0.5—1.5h)进行了基底元素穿透Au层的表面偏聚研究,给出了这一复杂系统中Ni,Co表面偏聚机理的直观证据,即Ni,Co主要是通过晶界扩散穿透Au层而后以表面扩散覆盖镀Au表面的;表面偏聚元素化学态的研究则不仅表明,氧的吸附和氧化反应是Ni,Co表面偏聚的驱动力,而且发现,上述偏聚会引起样品表面吸水的现象。

关键词: Au-Ni-Kovar合金系统 , surface segregation , substrate element , SAM , XPS

基于SAM的不锈钢点焊接头无损检测

孙鑫宇 , 曾凯 , 何晓聪 , 张龙 , 胡伟

宇航材料工艺 doi:10.3969/j.issn.1007-2330.2015.06.017

运用超声波扫描显微镜(SAM)对1 mm厚SUS304不锈钢薄板点焊接头进行无损检测,分析不同焊接工艺条件下的C扫描图像,并对C扫描图像各特征区域的A扫描信号进行采集、分析,研究两者间的对应关系,通过超声波C扫描成像法对焊核直径进行测量.结果表明:超声波扫描显微镜可以检测不锈钢点焊接头缺陷,并通过C扫描图像区分缺陷类型;在电极压力为0.15 MPa、焊接电流大于8 kA时,C扫描图像可以清楚的反映飞溅、过烧等缺陷;C扫描图像各特征区域表现出不同的A扫描信号特征;基于超声波C扫描测量的焊核直径为4.39-5.25 mm.

关键词: SUS304不锈钢 , 点焊接头 , 超声波C扫描 , A扫描

SAM ANALYSIS OF NITRIDE IN 30CrNi STEEL

QI Yunxin Nei Monggol Institute of Metallic Materials , Baotou , China QI Yunxin , Professor , P.O.Box No.4 , Baotou 014034 , Nei Monggol , China

金属学报(英文版)

The nitride in 30CrNi steel and its composition along boundaries have been studied by means of scanning Auger microprobe.The nitride identified metallographically is Zr(C,N)which contains a small amount of Ti and O.The interface width between the Zr(C,N)and the matrix is about 1.6 μm.An Fe-rich shell is.found on the surface of Zr(C,N)which appeared on the fracture surface.The thickness of shell is 0.1-0.8μm.The Fe concentration of its outmost layer is 3-18 at.-% and decreases exponentially along the depth direction.

关键词: nitride , null , null , null , null

CNTs/RE-SAM的制备及其吸收光谱分析

雷子恒 , 王传英 , 程先华

表面技术

用混和酸对碳纳米管进行功能化处理,并配制稀土改性碳纳米管悬浮液,通过自组装技术在单晶硅表面制备稀土改性碳纳米管复合薄膜.XPS和SEM检测结果表明:功能化处理后,碳纳米管表面含有羟基、羧基等官能团；稀土改性溶液中稀土的质量分数为0.3％时,对碳纳米管的改性效果最明显.从吸收光谱可以看出,稀土改性碳纳米管复合薄膜在紫外-可见光区域均有吸收,特征峰相对密集在紫外光区域,能够拓展晶体硅太阳能电池的光谱响应范围.

关键词: 碳纳米管 , 稀土 , 功能化 , 吸收光谱

Factors affecting the quality and corrosion inhibition ability of self-assembled monolayers of a Schiff base

Corrosion

Self-assembled monolayers (SAM) of a Schiff base were prepared on a copper surface under different conditions, and the quality and protection ability of resulting films against aqueous corrosion of copper were evaluated by alternating current (AC) impedance technique. Some factors, including surface treatment and applied potentials during and after self-assembly, were investigated. The results indicate that nitric acid (HNO3) etching of the copper prior to adsorption can improve the quality and corrosion inhibition ability of SAM significantly. An appropriately applied potential during self-assembly contributed to the improvement of the quality of SAM, and the long hydrocarbon chain in the molecular structure of the Schiff base enhanced the protection of SAM. Fourier transform infrared (FTIR) reflection spectroscopy and x-ray photoelectron spectroscopy (XPS) were used in the analysis of SAM.

关键词: alternating current impedance;aqueous corrosion;copper;films;Fourier;transform infrared reflection spectroscopy;Schiff base;self-assembled;monolayers;x-ray photoelectron spectroscopy;electrochemical impedance spectroscopy;copper corrosion;protection;films;alkanethiols;coatings;nacl;eis