Some Effects of Corona Discharge Treatment of Biaxially-Oriented Polypropylene Film

The effects of the unit corona-treatment energy on the contact angle of various liquids, on the surface free energy, on the extent of oxidation of a surface layer, and on the adhesion of acrylic adhesive were studied using a biaxially-oriented polypropylene (BOPP) film. The surface free energy was determined with the van Oss-Chaudhury-Good (VCG) approach as well as with the wettability method. The extent of oxidation of the surface layer of the corona-treated BOPP film was evaluated with X-ray photoelectron spectroscopy. The adhesion strength of joints between the BOPP film and the acrylic adhesive was measured using the 180°-peel test.

In the range of the unit corona-treatment energy up to 1.2 kJ/m², a rapid increase in the surface free energy with the treatment energy is observed. In the range above that value, the surface free energy rises relatively slowly. The extent of oxidation of the surface layer and the adhesion strength of joints between the BOPP film and the acrylic adhesive are approximately in direct proportion to the unit energy of the corona treatment. A five-fold growth of the adhesion strength of the studied joints within the examined range of the treatment energy was found.     

Theoretical prediction of Grüneisen parameter for bulk metallic glasses

The Grüneisen parameter (γ) is of considerable importance to Earth scientists because it sets limitations on the thermo elastic properties of the lower mantle and core. However, there are several formulations of the Grüneisen parameter in frequent use which not only give different values for Grüneisen parameter at ambient pressure but also predict a varying dependence of Grüneisen parameter as a function of compression. The Grüneisen parameter is directly related to the equation of state (EOS), yet it is often the case that both the form of and the EOS are chosen independently of each other and somewhat arbitrarily. In this paper we have assessed some of the more common definitions of the Grüneisen parameter and the EOS's, and have applied them to test the validity of EOS for six different bulk metallic glasses.     

A mathematical model to analyze heat and mass transfer characteristics of a CPL evaporator porous wick

A capillary pumped loop (CPL), because of its high power thermal transport character, has been developed as an attractive system for the thermal discharge of electronic chips with high power loads, especially on spacecrafts. A working fluid having relatively larger heat of evaporation, methanol for example, may transfer significant heat flux. In this paper a new mathematic model is constructed, in which the most important character is the treatment or the unsaturated region of the evaporator porous wick. Numerical simulation of heat and mass transfer in the evaporator porous wick is carried out with a new three‐layer model. The importance of unsaturated layer to simulate the present problem is clear. © 2005 Wiley Periodicals, Inc. Heat Trans Asian Res, 34(4): 209–218, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.20066     

Properties of Auger electrons following excitation of polarized atoms by polarized electrons

In non-relativistic approximation, the most general expression for differential cross sections describing the properties of Auger-electron emission induced in the excitation of polarized atoms by polarized electrons is obtained for the first time. The ways of the application of the general expressions suitable for the specific experimental conditions are outlined by deriving the expressions for the asymmetry parameters and the magnetic dichroism of the angular distribution of the Auger electrons as well as of the angular correlations between the scattered and Auger electrons.     

天然钠基膨润土防水毯长效耐久防水工艺

介绍了地下结构工程的常用防水方法，通过工程实例，提出了施作天然纳基膨润土防水毯防水的新工艺，指出该工艺对地下结构工程在长效、耐久防水性能方面具有一定的参考价值。     

反应温度及时间对奥氏体不锈钢渗铬层组织结构的影响

利用固体粉末包埋技术对316H奥氏体不锈钢进行了1090℃保温0.5～20 h和750～1150℃保温10 h的化学热处理,研究了不同工艺参数对渗铬层组织结构和耐磨性的影响。通过光学金相显微镜(OM),扫描电镜(SEM),能谱仪(EDS)以及X射线衍射仪(XRD)等分析手段,研究了保温时间和反应温度对渗铬层的微观组织结构的影响规律,使用摩擦磨损试验机研究了不同工艺参数对渗铬层耐磨性的影响。结果表明:反应温度对渗铬层的厚度影响显著,在同一温度下进行渗铬,渗铬层的厚度与渗铬时间呈抛物线关系;渗铬层主要由Cr_(23)C_6、Cr_2C和α-Fe-Cr固溶体组成,在渗铬过程中,首先在试样表面形成碳铬化物层,随着反应温度提高或保温时间延长,在碳铬化合物层下会生成α-Fe-Cr固溶体层,进一步提高反应温度和保温时间,碳铬化合物层逐渐消失。渗铬后试样的耐磨性明显提高,且在相同温度下渗铬,保温时间短的耐磨性好;相同保温时间,反应温度低的耐磨性好。     

原子层沉积Al2O3 保护层氢终端金刚石MISFETs的电学特性

研究了Zr-Si-N氢终端金刚石（H-diamond）绝缘栅场效应晶体管（MISFET）在有无Al₂O₃保护层情况下的电学特性。分别采用原子层沉积法（ALD）和射频溅射法（RF）制备了Al₂O₃保护层和Zr-Si-N栅介质层。MISFETs的转移特性曲线表明,其栅阈值电压在有无Al₂O₃保护的情况下从-2.5 V变化到3 V,表明器件从常关型转换为常开型。输出和转移特性曲线揭示了氧化铝的存在保护了氢终端,使其免受磁控溅射过程的损伤。     

Microstructure and mechanical properties of Ti-6Al-4V/Ti-22Al-25Nb joint formed by diffusion bonding

Ti-6Al-4V (wt.%) and Ti-22Al-25Nb (at.%) were joined by diffusion bonding at 950 °C and 15 MPa for 100 min, and the microstructure and mechanical properties of the resulting joints were investigated. The composition of the diffusion layer is B2/discontinuous α/α₂ layer/necklace-shaped β+α′ layer, where the content of any element at a given point mainly depends on the distance of the point from the interface and the phase type at the point. The tensile strength of the joint is 894 MPa, which is almost the same as that of the Ti-22Al-25Nb base alloy. The fracture surfaces on both sides of the joint are composed of two main regions. One region displays a relatively flat surface and fractures along the bonding interface. The other is composed of a moderate number of irregularly-shaped cavities on the Ti-6Al-4V side and many irregularly-shaped bulges on the Ti-22Al-25Nb side. Both regions result from fracture along the boundaries between β+α′ layers and α_p grains or from the transcrystalline fracture of α_p grains.     

基于ALD低温制备的纳米涂层刀具性能研究

目的 探索基于原子层沉积法(Atomic Layer Deposition,ALD)的纳米涂层低温制备技术,并重点研究涂层沉积过程及纳米氧化铝涂层对刀具力学性能的影响.方法 利用原子层沉积法,在200℃的环境下制备不同涂层厚度的纳米Al2O3涂层刀具,对涂层的微观组织、厚度、硬度、断裂韧性、断口形貌、弯曲强度、结合力及摩擦系数进行检测.结果 ALD沉积技术能将纳米涂层均匀沉积在YT5刀具表面,且涂层光滑,无滴状气泡,涂层厚度可以精确控制在纳米级.ALD涂层与基体结合力的大小与涂层厚度相关,随着涂层厚度增大,结合力呈先增后降的趋势,测得50、100、200 nm等3种纳米涂层结合力大小分别为11.07、12.74、7.86 N.纳米涂层能够提高刀具的硬度,显著降低刀具表面的摩擦系数,测得刀具摩擦系数分别为0.56、0.43、0.67,最高降低摩擦系数达40％以上.此外在200℃的沉积温度下,没有产生金属相变,因而对刀具基体没有影响,刀具的断裂韧性和弯曲强度没有降低.结论 基于ALD的纳米涂层低温沉积技术所制备的纳米涂层刀具,具有良好的力学性能及涂层-基体界面结合力,能显著提高刀具性能,改善切削加工条件.