This study explores an improved method of welding austenitic stainless steel. The method uses two series connected arcs to weld the workpiece simultaneously from opposite sides. Owing to this arc configuration, the welding current is forced to flow from one arc to the other through the workpiece. It is known that such current flow concentrates the arcs and thus improves the penetration capability. Also, the current flowing through the workpiece generates fluid flow within the weld pool. In addition, owing to the use of the two opposite arcs, the heating tends to be symmetric. In addition to the increased penetration, the use of this method for welding austenitic stainless steel results in improved microstructure in the resultant welds because of an increased columnar to equiaxed transition and a decreased angular distortion, which sometimes induces solidification cracking.

利用扩散火焰合成碳纳米管是一项新的技术和方法。介绍了这种新方法的基本原理，较系统地研究了火焰参数、基板材料、合成时间等对碳纳米管形态的影响。初步研究表明它在无外加催化剂的情况下也能合成碳纳米管，具有“自生催化”的特点。

Due to its popularity and high crack sensitivity, 6061 aluminum alloy was selected as a test material for the newly developed double-sided arc welding (DSAW) process. The microstructure, crack sensitivity, and porosity of DSAW weldments were studied systematically. The percentage of fine equiaxed grains in the fully penetrated welds is greatly increased. Residual stresses are reduced. Porosity in the welds is reduced and individual pores are smaller. It was also found that the shape and size of porosity is related to solidification substructure. In particular, a weld metal zone with equiaxed grains tends to form small and dispersed porosity, whereas elongated porosity tends to occur in columnar grains.

This paper introduces a process to synthesize well aligned carbon nanotubes (CNTs) from ethanol flames by using a uniform electric field generated from a DC power supply. It has been found that (1) comparing with the other processes a small electric field is enough to align CNTs; (2) the synthesis process becomes more controllable and repeatable; (3) the electric field also improves the diameter uniformity and the crystallinity of graphite sheets. It is thought that the alignment mechanism is due to the electrostatic force acting upon the catalyst particles at the tips of CNTs. The present process has advantages such as convenience of applying electric field, simple experiment set-up, and large area synthesis of well aligned CNTs.

The ethanol flame was successfully used to synthesize highly graphitic hollow-cored carbon nanotubes (CNTs) and novel disorder solidcored carbon nanofibers (CNFs). Their morphologies were characterized by using scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy and Raman spectroscopy. It was found that the mixture of CNTs and CNFs were grown on Ni-contained substrates, whereas only the CNFs were produced on carbon steel and low alloy steel substrates. It has been established that Ni and its compounds play a key role in CNTs growth and Fe and its compounds in CNFs growth. The models of 'hollowcored mechanism' and 'solid-cored mechanism' were proposed to explain the present CNTs and CNFs formations, based on the theory that 'Fe has a strong affinity for carbon and Ni has a weak affinity for carbon'. It is expected that the present ethanol flame may provide a much simpler and more economic approach for mass-production of CNTs and CNFs by using large flame or multi-flames.

采用气氛保护钎焊工艺，对AA4343/AA3003铝合金复合板材料的钎焊接头组织特征，及其与焊接工艺的关系和对接头区显微硬度的影响进行了研究。实验结果表明，钎焊过渡区由单相α（Al）固溶体层和Si扩散层组成，它们的厚度随钎焊条件而发生变化。远离焊接区有一个α（Al）固溶体残余层，它的厚度保持20μm基本不变，与焊接参数和材料性质无关。讨论了钎焊接头特征组织的形成机理。

本文利用民用液化石油气为碳源，在经过预处理的低碳钢和含Ni合金钢等基板上成功地制备出“空心”碳纳米管（CNTs）和“实心”碳纳米纤维（CNFs）等一维碳纳米材料。实验发现基板预处理对一维碳纳米材料的制备起着决定性的作用，如：机械研磨预处理时很难制备出一维碳纳米材料，而采用涂覆和电镀处理则很容易获得一维碳纳米材料。利用场发射枪高分辨扫描电镜（SEM）、透射电镜（TEM）和激光拉曼光谱（RS）等技术对碳纳米材料的结 构进行了表征。从本实验可以预见，制备一维碳纳米材料将变得更简单，更经济。

Different functionally graded 20 wt.% MgO-ZrO2yNiCrAl thermal barrier coatings were obtained through the plasma spraying process. The microstructures, chemical compositions and fractured surface were examined by means of electron probe microscopic analysis (EPMA), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The SEM and EPMA results showed that: (1) microstructures and compositions varied gradually in the coatings; (2) the elements Cr and Al were enriched along the sprayed lamellae boundaries and leaded to the formation of oxides. TEM observation enabled finding the formation of dense dislocations and deformation twins, and also the formation of the oxides Al2O3 and Cr2O3 between grain boundaries. The SEM observations of the fractured surface revealed that the intermediate graded layer had the compositive mechanical properties in strength and toughness, due to the microstructure improvement and relaxation of residual stress concentration.

A novel process for synthesizing carbon nanotubes (CNTs) in ethanol flames is described. The CNTs grow on a nanocrystalline Ni layer which was electro-deposited on a Ni substrate using periodic reverse (PR) pulse plating. The grain size of the plating and CNT morphology were revealed using XRD, SEM, TEM and Raman spectroscopy. It was found that the quality of the plating and the corresponding CNTs were related to two plating parameters: output pulse frequency (f) and duty cycle (r). The growth mechanism of CNTs in this process is discussed.