放顶煤液压支架插板与尾梁的立式工装设计

对现有的插板与尾梁之间的装配方法进行概括,分析其存在的缺陷和问题,设计一种立式工装。此种工装的使用,可以减少液压支架装配工时且对车间吊车的使用无伤害,消除了安全隐患。     

Investigation of La3 + Doped Yb2Sn2O7 as new thermal barrier materials

Low thermal conductivity is one of the key requirements for thermal barrier coating materials. From the consideration of crystal structure and ion radius, La^3 + Doped Yb₂Sn₂O₇ ceramics with pyrochlore crystal structures were synthesized by sol–gel method as candidates of thermal barrier materials in aero-engines. As La^3 + and Yb^3 + ions have the largest radius difference in lanthanoid group, La^3 + ions were expected to produce significant disorders by replacing Yb^3 + ions in cation layers of Yb₂Sn₂O₇. Both experimental and computational phase analyses were carried out, and good agreement had been obtained. The lattice constants of solid solution (La_xYb_1 − x)₂Sn₂O₇ (x = 0.3, 0.5, 0.7) increased linearly when the content of La^3 + was increased. The thermal properties (thermal conductivity and coefficients of thermal expansion) of the synthesized materials had been compared with traditional 8 wt.% yttria stabilized zirconia (8YSZ) and La₂Zr₂O₇ (LZ). It was found that La^3 + Doped Yb₂Sn₂O₇ exhibited lower thermal conductivities than un-doped stannates. Amongst all compositions studied, (La_0.5Yb_0.5)₂Sn₂O₇ exhibited the lowest thermal conductivity (0.851 W·m^− 1·K^− 1 at room temperature), which was much lower than that of 8YSZ (1.353 W·m^− 1·K^− 1), and possessed a high coefficient of thermal expansion (CTE), 13.530 × 10^− 6 K^− 1 at 950 °C.     

High strain-rate superplasticity of fine- and ultrafine-grained AA5083 aluminum alloy at intermediate temperatures

Superplastic behavior of fine and ultra fine-grained AA5083 Al alloy was examined using the shear punch test. To achieve fine- and ultra fine-grained microstructures, a relatively new severe plastic deformation (SPD) process, namely Double Equal Channel Lateral Extrusion (DECLE) was employed. The strain rate sensitivity indices (m) of samples were evaluated after 1, 2, 4, and 6 passes for shear strain rates in the range of 3 × 10^− 3 to 3 × 10^− 1 s^− 1 and temperatures in the range of 573 to 673 K. For microstructural observations, TEM images together with the corresponding SAED patterns were prepared and utilized. A considerable increase in the m-value was observed after the first pass of the operation for all testing temperatures. The best condition for achieving a good superplasticity for the alloy was found to be a single pass DECLE at 673 K in the strain rate range of 10^− 2 to 10^− 1 s^− 1. This process condition resulted in an m-value of 0.43, indicative of a high strain rate superplastic deformation behavior. Further passes of the SPD process did not show any sign of superplasticity until the last pass of the operation, during which the m-value slightly increased, compared with the previous pass.     

Microstructure and mechanical properties of LA51 and LA51–0.5Y alloys with different accumulated strains and rolling temperatures

Mg–5Li–1Al (LA51) and Mg–5Li–1Al–0.5Y (LA51–0.5Y) alloys were smelted and rolled with different accumulated strains (36% and 68%) and rolling temperatures (373 K and 573 K). The microstructure, mechanical properties, fracture morphology and texture of the specimens were investigated. Results show that, due to the PSN (particle stimulate nucleation) mechanism, the addition of 0.5 wt.% Y improves the deformation resistance and weakens the basal texture of LA51 alloy. The effect of Y on UTS (ultimate tensile strength) of as-rolled alloys is more obvious than that of the as-cast alloy. Accumulated strain and rolling temperature could influence the twinning number, slip systems and DRX (dynamic recrystallization), thus affecting the microstructure and mechanical properties of the alloy. Under the proper combination of the above factors, the as-rolled LA51–0.5Y alloy with an accumulated strain of 68% at 573 K possesses the best comprehensive mechanical properties.     

Controlled grafting superhydrophobic cellulose surface with environmentally-friendly short fluoroalkyl chains by ATRP

Short fluoroalkyl chain of C₃F₇ instead of longer fluoroalkyl chain (C > 7) was robustly grafted on cotton fibers via an atom transfer radical polymerization (ATRP) strategy. This study focused on the influence of different finishing parameters (synthetic approach, grafting concentration) and post-treatment (washing, drying) conditions on wettability, liquid adhesion, air permeability, and mechanical (dry abrasion and wet laundering) properties. The results indicated that C₃F₇ chain was successfully grafting by a developed ATRP technique to construct superhydrophobic cotton fabrics. The optimized surfaces demonstrated super-anti-wetting property with a contact angle of about 163.7 ± 2.5° and an ultralow droplet adhesion of 62.3 ± 2.6 μN. The wettability remained highly hydrophobic even after 40 abrasion or 35 laundering cycles. This work also demonstrated the rational design and elaboration strategy of short fluorine-containing chains are vital for the construction of super-anti-wetting surfaces with controllable droplet adhesions. The results indicated that the anti-wetting, abrasion and laundering properties are much more influenced by the grafting strategy. We believe that environmental-friendly short fluoroalkyl chain (C < 4) can also be utilized for the construction of cotton fabric with good anti-wetting property and potentially applied in some practical fields, e.g., anti-wetting/icing outdoor cloth or self-cleaning sport textile.     

316L／15CrMoR爆炸复合板结合区微观组织研究

针对实际工程应用的316L／15CrMoR爆炸复合板材,采用光学显微镜、扫描电镜（EDS）等手段对爆炸复合板结合区的形貌、波形、晶粒度、变形层厚度、扩散层和渗碳层等进行了检测及分析。研究结果表明：结合区具有强烈塑性变形、熔化和扩散等微观特征;结合区波形为小波分布,波长和波高平均值为1056和454μm;基板侧塑性变形区域的晶粒度分别为9．1,7．1,6．7和5．8级。波峰和波谷处变形层厚度分别为189和137μm;在较强爆炸载荷作用下不锈钢覆层侧出现了绝热剪切线,其长度在100～200μm范围之内,间距20～50μm。     

槽板弯曲工艺及模具设计

对槽板零件及其工艺性进行了分析,详细计算了该零件的毛坯长度、弯曲回弹量、弯曲力等工艺,参数,根据弯曲工艺的分析及其参数的计算结果,叙述了该零件弯曲模具的设计结构,说明了模具的工作过程,最后阐述了该弯曲模具的设计经过。     

掘进机总体设计参数的研究

主要从重心、可掘断面、截割生产率、装载生产率、输送机生产率、转载机生产率和离地最小间隙等多个方面阐述了在掘进机总体设计中应当考虑的因素,这将对以后的掘进机设计有很大的现实意义。     

井下设备电缆卷缆装置的改装设计

根据煤矿设备工作特点以及电缆卷缆设备的功能特点,提出了一种利用差速器调节卷缆速度,利用弹簧钢缓解电缆预紧力叠加问题的机械式卷缆装置,能够有效解决行走与卷缆不同步问题,同时对电缆卷缆过程中存在的预紧力叠加、排缆不整齐等问题有一定的缓解作用。     

基于Pro/E的CMZY2-100/18岩巷钻装机运动机构仿真

在Pro/E环境下完成了CMZY2-100/18型岩巷钻装机的整机建模和装配,应用机构分析模块,定义了合适的约束和驱动条件,对钻装机的工作装置进行了机构仿真,分析了其运动特性。