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.

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.

提出了一种利用脉冲电镀法在金属基板表面沉积一层具有催化活性的镍纳米晶，再将该基板放入乙醇火焰中合成碳纳米管（CNTs）和碳纳米纤维（CNFs）的方法。利用光学显微镜和X射线衍射仪（XRD）表征了镀层镍纳米晶的形貌和晶格特征，利用透射电镜（TEM）表征了碳纳米管的微观结构。实验研究了基板材料和电镀时间等因素对碳纳米管和碳纳米纤维合成的影响；初步讨论了其生长机理。

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.

将经不同条件处理后的cr5M0+A302异种焊接接头放入NAcE（TM-01-77）+H2s标准溶液中进行不同时间的腐蚀性研究，在扫描电镜（sEM）下逐次原位跟踪观察熔合区同一部位经不同腐蚀时间后的变化过程。研究结果表明：（1）与其它特征区相比，熔合区的耐腐蚀性能最差，产生“氢致剥离开裂”；（2）经过焊后热处理的熔合区的抗腐蚀性进一步降低；（3）宽熔合区具有较强的抗“剥离开裂”腐蚀能力。上述现象与熔合区组织不均匀、碳迁移、氢富集和应力集中等因素有关。