In-process estimation of fracture surface morphology during wheel scribing of a glass sheet by high-speed photoelastic observation

Defect-free glass separation techniques are in strong demand in glass processing industries. In this study, we intended to observe the internal stress field during/after wheel scribing of a glass sheet using the photoelastic method. First, we visualized the crack propagation behavior in a 0.7-mm-thick non-alkali glass sheet during mechanical scribing with a 2.0-mm-diameter serrated diamond wheel using high-speed imaging techniques. The observation results under various applied load conditions showed that the crack propagation behavior changed dramatically at a load of approximately 9–10 N; the generated crack hardly propagated in the thickness direction under lower load conditions, in contrast to the rapid propagation under higher load conditions. The fracture surface morphology that was observed after cleavage also changed, from damaged to defect-free surfaces with increments in the applied load around the transition point (9–10 N). This result indicated that the fracture surface morphology was determined by the crack propagation behavior. Second, the birefringence phase difference was measured from the upper side of the glass sheet to enable understanding of the stress fields induced by scribing wheel indentations. As a result, the phase differences that were distributed along the scribe line were shown to differ depending on the applied loads; the phase difference changed little under lower load conditions, but vanished immediately under higher load conditions. Therefore, these differences were dependent on whether or not rapid crack propagation occurred. The measured phase difference distribution thus included information about the crack propagation behavior, and this information could be used as a criterion for estimation of the fracture surface morphology. An in-process estimation method for the fracture surface morphology during mechanical wheel scribing was therefore developed based on high-speed polarization imaging techniques.     

ZL101A铸造铝轮毂断裂失效分析

摩托车铝轮毂在使用过程中发生断裂。采用断口分析方法对其断裂原因进行了分析。结果表明，ZL101A铸造铝合金零部件并未严格按照设计要求的热处理工艺进行加工，孔洞和成分偏析等缺陷以及大量的针状Si相和B(Al9Fe2Si2)相的存在，降低了材料的力学性能，是造成断裂的主要原因，摩托车铝轮毂断裂为一典型的脆性解理断裂。     

银镁合金内氧化组织及断裂特征

采用真空感应熔炼法制备Ag-0.2Mg合金,用金相显微镜、扫描电镜、维氏硬度仪和电子万能试验机分析合金内氧化的组织及力学性能,研究合金拉伸断裂特征。结果表明,在小于550℃处理后,组织为细小等轴晶粒;大于650℃处理时,表面存在细晶区,内部晶粒逐渐长大,氧化界面向中心移动。内氧化温度升高,硬度逐渐降低,强度增加,延伸率降低。650℃和750℃内氧化后,细晶区断口平滑,内氧化组织为沿晶断裂,未氧化组织为准解理断裂;750℃内氧化后断裂末端区出现微孔聚合型断裂;850℃时断口为小平面状沿晶断裂,不同晶粒及不同晶面的微观断裂特征不一致。同一晶粒两个晶面的微观韧窝中有Mg O团簇,形状主要为方形,两个晶面的Mg原子、MgO团簇分布不同。     

DNA promotes the activation of oxygen molecules by binuclear cobalt(II) compounds

We have observed that binuclear cobalt(II) compounds with H(HPTP), Co₂(HPTP)(CH₃COO)(ClO₄)₂ and Co₂(HPTP)Cl(ClO₄)₂, react with oxygen molecules when DNA is present in the solution, cleaving the DNA (H(HPTP) denotes N,N,N′,N′-tetrakis(2-pyridylmethyl)-1,3-diaminopropane-2- ol).     

湖北大狼山地区褶劈构造与成矿作用

对大狼山地区褶劈构造的几何学、运动学和动力学特征进行了初步的分析,揭示了褶劈构造为区内印支-燕山期三条大规模NIV向脆-韧性剪切带形成与发展的基础;通过褶劈带内元素地球化学特征和An、Ag及多金属矿赋存规律探讨,反映出褶劈构造对成矿元素的迁移与聚集起着积极作用。因此,区内褶劈构造既可作为脆-韧性剪切带的基本特征．又是寻找中低温构造热液型矿床的标志。     

柘溪大坝1#支墩劈头裂缝处理及效果分析

本文介绍了柘溪大坝1#支墩劈头裂缝水下处理施工情况,通过施工期间漏水量的变化,分析了影响漏水量变化的因素,通过施工结束后漏水情况,对处理的效果进行了分析。     

Physicochemical properties and photocatalytic hydrogen evolution of TiO2 films prepared by sol–gel processes

Anatase TiO₂ films were obtained on glass substrates using a sol–gel method using titanium isopropoxide as a precursor. The thickness of the film was about 140 nm for one coating, and the thickness is controlled by the number of coating cycles. The spectra of UV-VIS absorption indicated that the absorption edge of the TiO₂ films is ca. 385 nm, corresponding to the band gap energy of 3.20 eV. We obtained TiO₂ films having a high activity for the hydrogen evolution from photocatalytic water cleavage. By loading with 0.3 wt% Pt rate of hydrogen production increases. No influence of film thickness and calcination temperature on the photocatalytic property is observed.     

二苯甲烷二异氰酸酯清洁合成过程研究 Ⅱ.二苯甲烷二氨基甲酸甲酯催化合成及其分解

针对苯氨基甲酸甲酯(MPC)和甲醛(HCHO)缩合合成二苯甲烷二氨基甲酸甲酯(MDC),然后分解制备二苯甲烷二异氰酸酯(MDI)的反应,考察了不同催化剂的催化性能及反应工艺条件的影响.在MPC缩合反应中,盐酸既作为催化剂又作为溶剂,且母液循环使用两次时,MDC的收率为78.4%;若以ZnCl2为催化剂、硝基苯为溶剂时,MDC的收率为87.4%;若以笔者开发的固载化ZnCl2/AC作为催化剂,其单位摩尔ZnCl2的MDC收率远高于液体ZnCl2催化剂.以混合溶剂溶解MDC后,进行液相分解得到MDI,锌及其有机盐对该反应有较高的催化活性,当以锌粉为催化剂时,MDI收率为87.3%.