Research and Improvement on structure stability and corrosion resistance of nickel-base superalloy INCONEL alloy 740

INCONEL alloy 740 is a newly developed Ni–Cr–Co–Mo–Nb–Ti–Al superalloy in the application to ultra-supercritical boilers with steam temperatures up to 700 °C. By means of scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), micro-chemical phase analyses, and corrosion-resisting test, this paper investigates the structure stability of the alloy at elevated temperature and concentrates on coal ash corrosion performance of the alloy under the simulated coal ash/flue gas condition. Experimental results show that the most important structure instabilities of the alloy during prolonged aging are γ′ coarsening, γ′ to η transformation and G phase formation at grain boundary. The performance of corrosion resistance of the alloy would meet the requirement of ultra-supercritical boiler tubes. The phase computation by means of Thermo-Calc has been adopted in chemical composition modification for structure stability improvement. Two suggested new modified alloys in adjustment of the Al and Ti contents and in control of Si level, and also in maintenance of Cr content of the alloy were designed and melted for experimental investigation. These two modified alloys exhibit more stable microstructure during 760 °C long time aging.     

An equivalent uniaxial fatigue stress model for analyzing landing gear fuse pins

We study the biaxial stress state conditions in landing gear fuse pins in the fuse groove. This biaxial state comprises a combination of shear stresses which are usually the largest stresses in the fuse pin by design, and compressive stresses which keep the half-section of the fuse pin in equilibrium. Conventional fatigue analysis techniques use an equivalent uniaxial stress, based on the Mises stress of a pure-shear condition. The respective predicted fatigue damages are much higher than those obtained from fuse pin cyclic tests. A new equivalent uniaxial fatigue stress model is proposed that includes the additional compressive stress as a relief on the fatigue damage in the fuse groove, thereby explaining the observations from fuse pin tests. The model is used in conventional uniaxial strain-life fatigue software (Goodrich Aerospace’s Fatigue Life V2) to predict the fatigue damage on a landing gear fuse pin with a sample load spectrum. The results are then compared to the pure shear model, and to a biaxial finite element fatigue analysis. As compared to the equivalent Mises model, the proposed model provides less conservative estimation of the fuse pin fatigue life, the latter value being higher than that provided by the two-dimensional finite element calculation. __________ Translated from Problemy Prochnosti, No. 3, pp. 85–98, May–June, 2006.     

Wide-gap layered oxychalcogenide semiconductors: Materials, electronic structures and optoelectronic properties

Applying the concept of materials design for transparent conductive oxides to layered oxychalcogenides, several p-type and n-type layered oxychalcogenides were proposed as wide-gap semiconductors and their basic optical and electrical properties were examined. The layered oxychalcogenides are composed of ionic oxide layers and covalent chalcogenide layers, which bring wide-gap and conductive properties to these materials, respectively. The electronic structures of the materials were examined by normal/inverse photoemission spectroscopy and energy band calculations. The results of the examinations suggested that these materials possess unique features more than simple wide-gap semiconductors. Namely, the layered oxychalcogenides are considered to be extremely thin quantum wells composed of the oxide and chalcogenide layers or 2D chalcogenide crystals/molecules embedded in an oxide matrix. Observation of step-like absorption edges, large band gap energy and large exciton binding energy demonstrated these features originating from 2D density of states and quantum size effects in these layered materials.     

套管式直流蒸汽发生器动态特性仿真研究

套管式直流蒸汽发生器是一种采用双面传热的新型蒸汽发生器.在中心管和环管外侧与环形通道流体间热流密度相等的假设基础上,合理选择集中参数并应用可动边界的处理方法对套管式直流蒸汽发生器传热管进行了动态仿真.仿真结果与热工水力定性机理分析结果及相关的试验结果相符,从而验证了仿真方法是有效的.     

基于B样条自由曲面体间最短距离计算算法研究

提出了一种快速求解B样条曲线间最短距离的算法。该算法首先运用ULB方法,计算出两条NUBS曲线控制多边形间一对距离为极小值的点,以此对极小值点的连线方向作为曲线间最短距离的矢量方向,然后用爬山法求出两曲线在该矢量方向上的一对极值点,并以此对极值点作为拟牛顿迭代法求解非线性方程组的初始值,这样大大减少了求解方程组根的迭代次数,可快速求出精确解。最后把该算法扩展到NURBS自由曲面。     

圆形重力式网箱浮架结构在波浪作用下的运动响应

依据Stokes二阶波浪理论和莫里森(Morison)方法,对圆形重力式网箱的浮架结构在两种锚碇系统(折线形和直线形)的作用下,浮架上特定点的运动轨迹进行了数值计算与水槽试验,比较结果发现在研究的波况下浮架的运动位移受波长影响较小,而与波高关系密切,在锚碇系统的约束下水平位移远小于垂向位移。数值计算与试验数据吻合较好,表明了此计算方法的可行性,为进一步模拟浮架结构的受力与变形打下基础。     

广铜半连铸炉及1.5t炉增容后的供电改造

针对半连铸的生产扩大，增加炉子设备，供电增容及原设计的不足之处进行供电系统改造，以满足扩大生产的需要。     

现代化小型冷床上料装置结构设计分析及计算

近年来，由于轧钢工艺趋向于采用无扭轧制等先进技术，使轧制速度迅速提高，对冷床高速上料装置提出了更高的要求。冷床高速上料装置是冷床设计中的难点，也是关键设备，它的设计质量与安装精度直接决定着产品的最终质量。本文对冷床高速上料装置进行了结构分析与计算，对冷床的设计、维护有一定的指导意义。     

丁基黄原酸甲酸乙酯的合成及对黄铜矿浮选研究

考察了不同条件对丁基黄药合成丁基黄原酸甲酸乙酯(BXEF)的影响。研究结果表明,合成BXEF反应的最佳工艺参数为：反应温度25℃,反应时间200 min,n(丁基黄药)：n(氯甲酸乙酯)=1．04：1。在此条件下,BXEF的产率可以达到94．5%。对江西永平铜矿硫化物矿石的浮选试验结果表明,与丁基黄药相比,BXEF对硫化铜矿有更高的浮选回收率,而且铜精矿中铜的品位更高。对丁基黄药和BXEF的量子化学计算结果表明,BXEF比丁基黄药有更低的能量,稳定性更强。     

尖晶石锰酸锂的第一性原理计算

应用基于全势缀加平面波方法（Full LineAugmented Plane Wave，FLAPW）的第一性原理计算软件Wien2K，对尖晶石LiMn2O4和其理想脱锂终点Mn204化合物进行了研究。优化得到了二者及体心立方相Li的晶体结构，脱锂前后晶格参数以及O原予占位的变化规律和实验结果相一致；采用Rietveld方法计算了脱锂前后LixMn2O4的理论X射线衍射图谱，二者之间的变化规律，和采用同步X射线衍射对竞放电过程的尖晶石LiMn2O4结构进行分析得到结果相一致；理论预测了LiMn2O4的平均放电电压为4．05V，和实验结果相吻合。