La在A1_2O_(3(sf))/Al-5.0%Cu复合材料界面的分布及界面结构研究

挤压铸造A12O3(sf)/Al-5.0%Cu复合材料时添加适量稀土La,并研究了界面附近La元素的分布。添加稀土后能明显的改善纤维与基体的润湿性,并促进了界面反应的发生,在纤维与基体合金之间生成致密的厚度约2μm的过渡层,并建立了界面的生成及结构模型。     

Influence of Cold Rolling Reduction on Microstructure and Mechanical Properties of TWIP Steel

The influence of cold rolling reduction on microstructure and mechanical properties of the TWIP (ttwinning induced plasticity) steel was investigated. The results indicated that the steel had better comprehensive mechanical properties when cold rolling reduction was about 65.0% and the annealing temperature was 1000℃. The tensile strength of the steel is about 640MPa and the yield strength is higher than 255MPa, while the elongation is above 82%. The microstructure is composed of austenitic matrix and annealing twins at room temperature, at the same time, a significant amount of annealing twins and stacking faults are observed by transmission electron microscopy (TEM). Mechanical twins play a dominant role during deformation, and result in excellent mechanical properties.     

Room-temperature dry sliding wear behavior of γ-Ni/Mo2Ni3Si metal silicide “in situ” composites

Ni-base solid solution (γ) toughened Mo₂Ni₃Si metal silicide “in situ” composites were fabricated with different volume fraction of Mo₂Ni₃Si primary dendrite uniformly distributed in irregular Mo₂Ni₃Si/γ eutectic matrix. Results of room-temperature dry sliding wear tests indicated that the composite with a medium volume fraction of primary Mo₂Ni₃Si phase possessed the best wear resistance by optimum combination of the unique mechanical property of Laves phase Mo₂Ni₃Si and toughening effect of ductile γ phase. The primary wear mechanism is microplowing and soft-abrasion of the interdendritic Mo₂Ni₃Si/γ and subsequent brittle fracture of the hard Mo₂Ni₃Si primary dendrites. Ductile γ phase provided good toughening effect to Mo₂Ni₃Si Laves phase during dry sliding wear process.     

原位合成TiC/AZ91复合材料力学性能的研究

采用重熔稀释法原位制备了不同质量分数的TiC颗粒增强的镁基复合材料,并对复合材料进行了力学性能测试。结果表明,原位合成的镁基复合材料的强度相比基体合金有了明显提高,塑性稍微降低。镁基复合材料强度的增加主要是因为位错强化、弥散强化和细晶强化协调作用的结果。     

不同磨料粒度下WC体积分数对铁基表面复合材料磨损性能的影响

用负压铸渗工艺制备了WC/HT300基表面复合材料,研究了WC体积分数和冲蚀磨损浆料中的颗粒粒度对复合材料的抗冲蚀磨损性能的影响。对于同一种WC颗粒体积分数的复合材料,当浆料中的石英砂粒度大时,复合材料的体积磨损率较大,抗冲蚀磨损性能降低。WC体积分数为27%和36%的表面复合材料具有比其他WC体积分数复合材料优越的耐磨损性能;在磨料粒度为40~70目的工况下,WC体积分数为36%的复合材料,具有比体积分数为27%的复合材料优越的耐磨性能;但在磨料粒度增大到20~40目时,WC体积分数为27%的复合材料,具有比WC体积分数为36%的复合材料优越的耐磨损性能。     

SiCp/AlCuMgAgCe复合材料的显微组织与力学性能

采用压铸浸渗法制备了53%SiCp增强的AlCuMgAgCe基复合材料。通过X射线衍射、金相观察、扫描电镜与透射电镜分析以及力学性能测试,研究了SiCp/AlCuMgAgCe复合材料的显微组织与力学性能。结果显示,在AlCuMgAgCe合金中加入53%体积分数的SiC颗粒后,复合材料的组织致密,分布均匀,其断裂方式包括界面脱开、基体韧断和增强体开裂,SiC颗粒与基体之间并没有发生明显的界面反应。在185℃的等温时效析出过程中,复合材料的析出相主要由Ω相和少量θ′相组成。     

Microstructures and wear resistance of large WC particles reinforced surface metal matrix composites produced by plasma melt injection

Large WC particles (− 840 μm-+ 420 μm) reinforced surface metal matrix composites (SMMCs) were produced using plasma melt injection (PMI) process on a Q235 (similar to ASTM A570 Gr. A) low carbon steel substrate. Microstructures of the SMMC were observed using scanning electron microscope (SEM), and the composition was determined with energy dispersion spectroscopy (EDS). Phases were analyzed with X-ray diffraction. Micro-hardness of the SMMC was tested. Wear losses of the SMMC layer were evaluated under dry friction conditions and compared with those of the substrate material. The results show that the large WC particles are caught by crystallized metal and stay in the upper part of the SMMC layer, and there is only a little melting on the outer surface. No sinking down of WC particles occurs. The SMMC layer is well bonded to the substrate, and the interface is crack free. The wear resistance of the Q235 substrate is greatly improved with large WC particles injected.     

光伏板清洁机器人运动学建模与仿真

为实现光伏板清洁机器人的精准运动控制,运用D-H法建立光伏板清洁机器人臂架机构运动学数学模型。根据变量的性质,将光伏板清洁机器人臂架机构的运动学问题用驱动空间、关节空间、位姿空间之间的映射关系描述,根据机构的几何特征,分别推导出各工作空间之间的映射关系。在MATLAB环境下对臂架机构数学模型进行运动学仿真并绘制清洗装置末端轨迹包络图,验证光伏板清洁机器人臂架机构运动学数学模型的正确性。研究结果为光伏板清洁机器人轨迹规划、运动仿真与动力学分析等提供了理论依据。     

Recent Research on the Deformation Behavior of Particle Reinforced Magnesium Matrix Composite: A Review

Particle reinforced magnesium matrix composite(PMMC) possesses the merits of high specific strength, high specific modulus, better dimensional stability, good wear resistance and lower production cost, which is thought as a promising material in the field of aerospace, automobile, electronic communication, etc. To eliminate the casting defect, the PMMC is usually experienced hot deformation process. The present paper mainly focuses on the deformation behavior of PMMCs. First, the development of PMMCs based on particle size is introduced. Then, the hot deformation technology and deformation mechanism of PMMCs at elevated temperature are given and analyzed, respectively. After reviewing the dynamic recrystallization and texture of PMMCs, its future development is suggested based on the current research progress.     

基于灰色RBF神经网络模型的电梯层间交通分布预测

为了有效预测电梯的层间交通分布状态,提出一种层间交通O-D矩阵的预测方法．该方法融合灰色预测和神经网络方法各自的优点,将灰色预测方法与RBF神经网络有机结合,构造灰色神经网络预测模型．利用灰色预测中的累加生成运算（accumulatedgeneratingoperation,AGO）对原始观测数据进行变换,得到规律性较强的累加数据,作为神经网络的建模和训练样本．还提出了对不良交通需求数据的修正方法,以进一步降低观测数据的随机性．所提方法既避免了灰色预测方法存在的理论误差,又提高了神经网络的训练速度和预测精度,适用于短期层间交通分布预测．仿真试验验证了该方法的有效性．