Advanced Materials Research Vols. 753-755

Abstract: Alumina composites were joined in air by microwave heating, along with Al-Si alloy powder as the interlayer. The interfacial microstructure and the fracture surface were investigated by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). Element and phase components of the interlayer were analyzed by X-ray diffraction (XRD). Experimental results clearly indicated that microwave heating method effectively hampered the oxidation of the interlayer and indirectly promoted adhesion. The molten Al-Si alloy wetted and penetrated to the 95-Al₂O₃ ceramics surface, which formed the well joining interface.

Abstract: Nanometer Si powders were used as interlayer materials, which were expected to be microwave heated rapidly and reacted with the surface of Al₂O₃ ceramics to form the low eutectoid compound. The phenomena of element migration of joint samples were investigated by energy dispersive spectroscopy (EDS) and the interface phase transition was analyzed by X-ray diffraction (XRD). The results indicated that the low eutectoid compound of the joint interface wetted and penetrated to the ceramic surface. The variation of micro-hardness at the interface across the parent material was measured by micro-hardness instrument and the interfacial microstructure and the fracture surface were investigated by scanning electron microscopy (SEM).

Abstract: By using HL105 brazing piece as filler metal and the water soluble copper brazing agent made by self, we welded the coal cutter by induction brazing, which was used 42CrMo steel as the body and YG15 hard alloy as the head. By studying the microstructure and mechanical property of brazing seam, we found that the bending strength of the joint welded by using the home-made fluxes had achieved a superior level. The quality of brazing seam on the condition of the fluxes and water in a four-to-six ratio was superior to that when the fluxes is dewatering borax or the fluxes and water in a half-to-half ratio.

Abstract: The solid-state diffusion bonding experiments of high Nb containing TiAl alloy were successfully carried out at 950°C under a uniaxial pressure of 30MPa for 45min, and the influence of different initial microstructures, such as initial forged microstructure (named duplex microstructure) with different grain sizes, near lamellar microstructure and full lamellar microstructure, on the interface of the bonding joints were investigated. And the microstructure characterization of interfaces was taken by OM, SEM, EDS and micro-hardness tester. The results indicated that the grain size and strain energy are of great importance to improve the quality of interfacial bonding. Besides, the interfacial microstructure was found different from matrix and changed during the diffusion bonding process. Meanwhile, micro-hardness tests of the three kinds of joints showed that the micro-hardness in the interface was slightly higher than matrix in all the joints, resulted from the working hardening of the interface under the uniaxial pressure.

Abstract: The acoustic horn plays a very vital part in high energy ultrasonic machining, and its design is critical to the quality and the efficiency of ultrasonic machining. This paper performs the analysis and design of acoustic horns for ultrasonic welding Teflon encapsulated O-ring by employing ANSYS finite element software. Firstly, the theoretical dimensions of the horns are calculated. Moreover, their natural frequencies and amplitudes are obtained through the simulations of ANSYS.

Abstract: The difficulties of horizontal welding technology are stated in this paper. On the basis of analyzing the defects occurred during horizontal welding technology as well as several corresponding methods are adopted nowadays. Control measures for horizontal welding technology high efficiency can be summed up to two types: weld pool quick solidification control measure and weld pool stable shape measure. The development history of their research and application is reviewed. And the mechanism of producing weld defects is deeply analyzed. The prospects and development of horizontal welding technology are elaborated.

Abstract: Riveting effect is influenced greatly by riveting processes, and it is valuable to research them. Base on the current trends and development of sheet riveting, the methods and tools of sheet metal riveting are introduced in detail, including rivet riveting and riveting without rivet. The principle and characteristics of the tools are discussed and the existing defects of riveting technology are concluded.

Abstract: In order to achieve a more intensive understanding of the plate welding mechanism of the punch repairing process, a numerical simulation has been carried out by using the finite element method. According to the special requirement of the punch, which had been the wear failure, the surface welding surfacing have been taken into account in the finite element model. The results of the finite element simulation are in proper agreement with the experimental findings. The distributions of the Von Mises Stress of the workpiece have been computed for discussion. It has been realized that good results could be got by finite element computation.

Abstract: Using A-TIG to welding thick plate duralumin alloy and designing rationally welding processing for Y groove butt plates welding of duralumin alloy. Using repeated measurements of dot to get transverse and vertical welding deformation under different current of A-TIG after welding. This paper analyzed the influence of different current on welding deformation and the features of A-TIG welding deformation. The result showed that transverse deformation was the uniformity along weld direction but was not uniform along weld vertical direction. Transverse deformation was larger when it was nearer to weld. Vertical deformation of middle position of weld was smaller than the part of arc starting and arc suppression. The result also showed that the deformation increased as the current increased.

Abstract: The technological and economic advantages of laser welding of plastics in comparison to the traditional welding process and research situation are analyzed in this paper. Process methods of this technology are reviewed as well as the range of application for these manners is compared. The technological challenges facing the further development of the technology and the critical issues needing to be solved are deeply investigated. It is pointed out that efficient prevention of plastics distortion and cracking as well as control of internal structure and defects are currently the two bottleneck obstacles challenging the further development and industrial applications of the revolutionary advanced manufacturing technology. The developments of laser welding technology of plastics in the future are also forecasted.