Showing papers on "Cold welding published in 1981"

The structure and properties of aluminum alloys produced by mechanical alloying: Powder processing and resultant powder structures

Abstract: Mechanical alloying of two aluminum alloy powders to form composite A1-A12O3 powders has been studied. Changes in powder microstructure with processing are reported and interpreted. Mechanical alloying proceeds by the continual cold welding and fracturing of the constituent powder particles when subjected to the large compressive forces of a high speed mill. A suitable organic surfactant must be added so that a balance between cold welding and fracturing is obtained. The organic surfactant is embedded and finely distributed in the powder particles during mechanical alloying and is converted to discrete A14C3 particles after hot pressing. The establishment of steady state processing conditions, characterized by equiaxed powder particles, a constant particle size distribution and a saturation hardness, is found to depend on the size distribution of the initial powders. The oxide particles formed and distributed during mechanical alloying are equiaxed, small (30 nm) and homogeneously distributed with a volumetric center to center distance of about 60 nm.

Low expansion laser welding arrangement

Abstract: An arrangement for laser beam welding wherein at least one of the components being welded is formed of a material which is substantially transparent to radiation at the wavelength of the laser welding beam. A layer of welding material is placed over the surface area of the weld joint, and is a type of material which is substantially absorbent of radiation at the wavelength of the laser welding beam. The welding material is then irradiated by the laser beam through the component which is substantially transparent thereto for a sufficient period of time to cause melting of the welding material and fusion thereof to the two components being welded. The present invention has particular applicability to welding with a Nd-YAG laser of components formed of silica-containing material, such as fused silica or titanium silicate, and wherein the welding material placed at the weld surface area is a titanium based material. The present invention is also particularly attractive for weld locations which are physically inaccessible to direct irradiation, but can be irradiated through the material which is substantially transparent to the laser welding beam.

Microstructure and Bonding Mechanism in Explosive Welding

Abstract: The use of transmission electron microscopy (TEM) to examine the microstructure of the bonding zone in explosive welding is described. Plates of an aluminum copper alloy were heat-treated to produce a well defined microstructure. With such plates a series of claddings with different parameters and conditions were made. The microstructure of the bonding zone was then analysed. From the changes of microstructure within the bonding zone as compared to the microstructure of the material in the original state conclusions are drawn concerning the deformation process and the thermally activated reactions which take place during welding. The findings lead to a more comprehensive understanding of the explosive bonding process, including maximum temperature within the bonding zone, cooling rate, and deformation mechanism during the impact of the plates. It can be shown that bonding is achieved by short time melting followed by extremely rapid solidification and cooling of a very thin layer along the contact interface. A brief discussion on the generalization of the results to include materials with high melting temperature, and the correlation between the microstructure and properties of explosive welds is presented.

Electric resistance welding using energy beam in combination

Abstract: PURPOSE:To perform welding of high quality free from welding defects using relatively simple device by irradiating an energy beam to an apex which becomes the welding point of an wedge-shaped object to be welded and making combined use with electric resistance welding. CONSTITUTION:High frequency voltage is applied to contacts 4, 4 disposed on the edge part 2 of a tubular body 1 for manufacturing an electric welded tube etc. to heat the edge part 2, and welding is performed at the apex of the wedge- shape. An energy beam F is irradiated in the direction of the apex of the wedge by a laser irradiating device and mirrors 6, 7, 8, 9 etc., and the corner part 21 and thick central part 22 of the edge part are heated uniformly to prevent occurrence of welding deffects. Efficiency of uniform heating can be increased by supplying highly ionizing gas to a space just in front of the apex of the wedge of the weld zone to generate plasma, and work efficiency of welding can be improved by controlling heat input of welding automatically.

Method of welding using a covered tungsten electrode

Abstract: A method of welding which utilizes a metal electrode core encased within a pre-sintered ceramic insulating sleeve. The method comprising, preplacing a welding wire in the welding kerf formed between the pieces to be welded, tacking the welding wire in place such that the wire abuts the surface of the pieces to be welded, guiding the metal core electrode rod encased in a ceramic pre-sintered sleeve over the welding wire, and simultaneously, torching the welding wire so that a uniform weld deposit is formed.

Recent advances in Pt coating of microspheres by a batch magnetron sputtering process

Abstract: Some proposed inertial confinement fusion targets require high‐Z, high density metal coatings on glass microspheres. Platinum, which satisfies the high‐Z and density requirements, can be coated onto microspheres with a batch magnetron sputtering process incorporating oxygen as a dopant gas to prevent the microspheres from sticking. This paper outlines recent progress in three areas: First, the coating process has been improved; second, the oxygen content and resistivity of the oxygen doped platinum films are analyzed; and third, the roles oxygen may play in reducing microsphere sticking during sputtering are discussed in regard to cold welding, Van der Waals bonding, electrostatic sticking, and sintering.

Apparatus for welding together two plastic sheets.

Abstract: In devices for welding together two plastic sheets (6, 7), in particular for the production of welds, the sheets are clamped between two welding tools (1, 2). One of the two welding tools is equipped with heating means. In order to make the device independent of readjustments or setting operations for differences in the thickness of the sheets, the heating means are arranged and designed in such a way that the heated welding tool is held essentially at a uniform temperature. The other welding tool (2) is provided with a thermocouple (13) which has the effect of releasing the clamping of the plastic films between the welding tools when a predetermined temperature has been reached.