Johnson-Cook dynamic constitutive relationship for TC 16 titanium alloy

The true stress--strain curves of TC16 alloy with a wide range of strain rates were investigated under uniaxial quasi-static tension and uniaxial dynamic compression with the lnstron 8032 test machine and the split Hopkinson bar respectively. The results indicate that the true stress increases with increasing strain rate, while decreases with increasing temperature. Under the 105 s^-1 high strain rate and temperature higher than 673 K, the true stress would even be less than that under quasi-static condition. A new method incorporating TCl6＇s stress strain curve developing item was proposed to determine the coefficients in J-C model easily and to avoid the estimation of the adiabatic temperature rising. The Johnson-Cook dynamic constitutive relationship for TC16 was obtained for the first time. Good agreement was obtained between the model prediction and the experimental stress--strain curves for TC16 under both quasi-static and dynamic loadings.     

La1-xSrxCo1-yFeyO3材料制备及结构分析

以溶胶-凝胶法制备La1-xSrxCo1-yFeyO3粉体,对粉体在不同温度热处理后的晶体结构进行XRD表征,详细研究粉体的成分组成以及发生的结构转变.结果表明,凝胶前驱体粉体颗粒比表面增大有利于钙钛矿结构晶相形成;合成粉体受前驱体比表面程度影响形成两种具有不同空间群钙钛矿结构晶相,并且各晶相元素化学计量比不相同,两相体系较稳定.     

吡咯对电沉积磷酸钙类复合涂层的生长方式的影响

利用电化学沉积的方法,在电解液中加入吡咯,制备了磷酸钙-聚吡咯复合涂层.结果表明:吡咯使涂层的生长方式发生了改变.未加入吡咯获得的单一的磷酸钙沉积陶瓷膜呈现无序排列,叶片状.电解液中加入吡咯后,陶瓷膜层有序排列,呈针状且整个膜层的晶粒增大.红外光谱分析表明,出现了C=C和N-H基团的伸缩振动吸收峰,说明吡咯已经由电解液中转移到涂层中.相分析表明:吡咯的加入并没有改变涂层的相组成,说明整个过程中仅有少量的吡咯进入涂层.     

Evolution of {001 } （110） orientation and related lattice rotation of A1 alloy 6111 during rolling

The texture evolution and lattice rotation in A1 alloy 6111 with an initial {001} （110）component during symmetrical and asymmetrical roiling were investigated by means of orientation distribution function（ODF）. The results show that the as-rolled initial {001 } （110） orientation evolves into not only the copper orientation but also all the other orientations along the β fiber, including the brass orientation, by lattice rotation around special directions. Compared with the symmetrical rolling, the {001 } （110）component in the surface layer on the slower roller side evolves more quickly into the orientations along the β fiber during asymmetrical rolling, while that in the surface layer on the faster roller side evolves more slowly.     

Investigation on gradient material fabrication with electron beam melting based on scanning track control

A new electron beam control system was developed in a general vacuum electron beam machine by assembling with industrial control computer, programmable logic control （PLC）, deflection coil, data acquisition card, power amplifier, etc. In this control system, scanning track and energy distribution of electron beam could be edited off-line, real-time adjusted and controlled on-line. Ti-Mo gradient material （GM） with high temperature resistant was fabricated using the technology of electron beam melting. The melting processes include three steps, such as preheating, melting, and homogenizing. The results show that the GM prepared by melting technology has fine appearance, and it has good integrated interface with the Ti alloy. Mo and Ti elements are gradually distributed in the inter.face of the gradient material. The microstructure close to the Ti alloy base metal is α ＋ β basket-waver grain, and the microstructure close to the GM is a single phase of β solid solution.     

关于输气管线内衬聚乙烯管可防止其腐蚀的商榷

本文参照德国一实例，即利用多种类型PE衬层，在一定温差及有气体扩散阻挡层和无气体扩散阻挡层的条件下，详细地叙述了高压酸性气体对其进行长期渗透作用的试验。结果显示：水蒸气和腐蚀性气体（如H2S）的渗透作用是不能忽视的，甚至当PE层为5mm时亦有一定渗透性；此外，在衬层底部尚产生了化学腐蚀作用，从而促使人们必须考虑须正确选择PE下边的防腐底层。     

Cu-Ag合金强度与弹性模量在组织纤维化过程中的变化

采用冷拉拔制备了Cu-6％Ag及Cu-12％Ag纤维相复合强化合金线材，研究了组织纤维化对Cu—Ag合金强度与弹性模量的影响。随变形程度的增加，合金抗拉强度和弹性模量在明显升高后趋于饱和。Cu-12％Ag合金比Cu-6％Ag合金有更高的应变硬化速率和抗拉强度。在较低变形程度范围内，Cu-6％Ag合金的弹性模量高于Cu-12％Ag合金。在较高变形程度范围内，Cu-6％Ag合金的弹性模量低于Cu-12％Ag合金。纤维化组织中的高密度晶体缺陷使得两种Ag含量的合金弹性模量均低于理论预测值。合金的强度和弹性模量主要取决于共晶体数量、相界面密度、变形抗力及两相之间的变形协调行为。     

隧道式热风循环电热干燥炉及其应用

本文介绍了一种干燥效率高、节能降耗、温差小、干燥产品质量高的隧道式热风循环电热干燥炉.该炉采用多点分区控温,各均温区为一个热风循环组元,实现炉内双侧纵横双向热风循环,热风循环组元根据干燥传热学按干燥第一阶段、第二阶段在干燥炉长度方向间距不同布置.可根据产品规格和工艺需要,实现严格的温度曲线,同时也便于调整.热风循环装置应用于隧道式干燥炉,能强化对流换热,均匀炉温,提高干燥质量.推广应用结果表明:本炉型非常适合于规模化生产高质量树脂磨具,比箱式炉可节能约40%.     

机械热化学法制备纳米W-Cu复合粉末及其烧结性能研究

WO3和CuO原料粉末经气流粉碎后,在H2气氛中进行共还原,制得了Cu含量为20%(wt%)的纳米W-Cu复合粉末;通过X射线衍射,透射电镜和扫描电镜等方法研究分析所制备W-Cu粉末的烧结行为和烧结体性能.结果表明:气流粉碎可以明显地降低WO3和CuO的粒度;通过对气流粉碎氧化物粉末进行共还原,可获得粒度为50～100nm的W-Cu复合粉末.该粉末烧结活性较高,其成形压坯在1200℃下于H2气氛中烧结后相对密度可达98%以上,且烧结体晶粒细小均匀.其抗弯强度和维氏硬度分别超过1000MPa和300MPa,电导率高于35%IACS.     

Surface modification and characterizations of basalt fibers with non-thermal plasma

Atmospheric-pressure non-thermal plasmas have been increasingly promoted for polymer surface modification. In this paper, atmospheric-pressure plasmas of oxygen, argon, hydrogen and mixture gases of nitrogen and hydrogen were used to surface modification of basalt fibers in order to illuminate their chemical durability, surface active groups and roughness etc. The plasma-induced surface changes on morphologies and active groups were characterized by scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). The results exhibited a remarkable increase in chemical stability and excellent adhesion, accompanied by extensive etching and by the implantation of both oxygen- and nitrogen-containing polar groups such as NH₂, OH and so forth. Etching of oxygen was mainly a consequence of ion bombardment, yielding low molecular weight and roughness, while surface chemical modifications of mixture of hydrogen and nitrogen were mainly due to the action of neutral species on the plasma-activated basalt fiber surface. The possible formation mechanism of functional groups on the basalt fiber surface was presented.