Papers by Keyword: Plasma Arc

Abstract: This article offers a qualitatively new approach for production fused welding fluxes granules, based on the use of a plasma arc and the Ural region raw materials that have a particularly low content of harmful impurities. The processes of fused welding flux granules forming from the Ural region mineral raw materials under the impact of a highly concentrated energy source have been studied. A new fused welding flux for submerged arc welding is produced by plasma electric arc granulation, and has required shape and fractional, chemical and phase composition of the particles. This research presents experimental and theoretical studies of interaction processes of fine-dispersed batch from mineral raw materials with a highly concentrated energy source, aimed at obtaining new information about the basic patterns of the formation, structure and composition of resulting granules of functional materials, such as welding fused fluxes.

Abstract: The article outlines the main principles of granulation technology for fused welding flux using highly concentrated heat sources (e.g. plasma arc). Modern plasma equipment and methods of its use for producing new welding materials (plasma-granulated welding flux) from mineral raw materials and synthetic mineral alloys are described. The developed technology makes it possible to produce granulated flux in a wide range of fractional composition (from 0.2 to 3 mm). Studies have focused on the influence of granulation regimes (plasmatron moving speed, current, voltage, arc length) on formation process and the morphology of welding flux particles. Mineral raw materials used for granulation were igneous rocks (basalt, hornblendite) and synthetic mineral alloys. The results obtained during experiments on the use of highly concentrated heat sources for granulation of a fused welding flux confirm the feasibility and prospects of this technology. Typical equipment for air-plasma cutting is used, and no new complex technological equipment is required, therefore it eliminates large material and labor costs.

Abstract: Plasma torch is one of the most important parts for plasma arc generating system. A design of orifices in a nozzle would decide the properties of plasma arc. However, mechanisms of orifice to plasma arc are seldom discussed. In this paper, the plasma arc with two assistant orifices were analyzed by finite element method. It was concluded that the plasma arc would be further compressed in the direction parallel to two assistant orifices, but expand perpendicular to assistant orifices. Through the constriction of two assistant orifices, the shape of the plasma arc would be elliptical other than circular of the oridinary plasma arc. The torch design with two assistant orifices could be available to many fields such as plasma arc welding, especially to a welding torch with a large pressure chamber.

Abstract: Flame hardening has been traditionally used for selective surface hardening of steel. This technique frequently resulting in imprecise harden area and part distortion when overheated. Focused heating source such as plasma arc can be an alternative to overcome this problem. In this work, plasma arc is scanned at the 4340 steel surface to improve the hardness. The variable parameters investigated were at scanning speed and operating current. Four types of surfaces were observed after they are scanned with plasma arc. They are fully-melted, partially-melted, non-melted continuous and non-melted intermittent where each type of surface has different roughness value. This work found that scanning speed and operating current has significantly influence the type of surface and roughness values. Analysis on non-melted surface gives the maximum depth of hardened layer of about 187 μm as well as hardness values of about 990 HV₅₀. It is also observed that the depth of hardened layer and hardness value is significantly decreasing with increase in scanning speed or the decrease in operating current. Microstructure examination on hardened layer revealed that the increase of hardness is due to formation of fine grain martensitie structure.

Abstract: Plasma is ionized gas-like substance, comprised by the e-deprived atoms and electron-positron. Plasma possess the characteristics of high energy, high thermal capacity, fast response and electric conversion efficiency, which shows unique advantages and good prospects for the effective disposal of POPs wastes. This paper introduced the basic principle and mechanism of plasma arc technology as a non-combustion technology; reviewed the development of application of plasma technology in the processing of HFC23, organic fluoride industrial waste, phenyl chlorosilane residue, medical waste, printed circuit board, chemical weapons and other hazardous wastes; analyzed the major technical and economic advantages and disadvantages for the plasma technologies in the POPs waste treatment; And corresponding comments and suggestions were proposed to promote the application of plasma technology for POPs waste disposal in China.

Abstract: The technology of metal surface strengthening with plasma arc has quite different characteristics of High frequency quenching. The results similar to that of the laser beam. The properties make it possible that develop a plasma arc heating robot as a portable device for the case surface strengthening of steels. The characters of the plasma are analyzed at first, then the plasma arc as Guess distribution circular heat source is studied to create the surface strengthening temperature field and heating process. The surface strengthening technology and the hardware design of the plasma arc surface- strengthening robot is given.

Abstract: In order to systematically study the morphology and distribution of M₇C₃ and TiC which in situ synthesized by plasma arc in the surfacing layer, plasma arc was used to clad the Fe-Cr-Ti-C wear-resistant alloy on low-carbon steel. And high corrosion experiment was applied to the surfacing layer. The hardness, microstructure and phase constitution of the surfacing layer were investigated through the tests of hardness, OM, EDS, SEM and XRD analysis. The results shows that irregular hexagonal (Cross-section) and strip (Side) M₇C₃ and petal-like, granular TiC were in situ synthesized in the surfacing layer. The M₇C₃ and TiC was combined closely. The M₇C₃ grains which closed to the fusion line of the base metal and surfacing layer are fine, but the ones that away from the fusion line are larger caused by the large temperature gradient. Smooth metallurgical bonding layer was formed between the surfacing layer and the base metal, it has a good metallurgical bonding. The phenomenon that carbon diffusion into the base material was clearly, the hardness near the fusion zone was improved effectively.

Abstract: Plasma arc was used as a heat source to make a surface quenching on alloy cast iron, and orthogonal test was used to optimize the surface hardening technological parameter of plasma arc. The influence of the technological parameters on hardness and depth of the hardening layer was analyzed, and the microhardness and the microscopic structure condition after being disposed were also analyzed and discussed.

Abstract: Thermally enhanced machining is an effective way of processing hard and brittle materials. The Wear performance of diamond saw blade cutting granite plate by Plasma-assisted heating is studied by a homemade experimental device. Investigation of the blade wear in different suspension and heating scan rate shows that by plasma arc heating, the tool wear rate has a significant reduction. A technology for the efficient stone machining and further industrial applications is provided in this paper.

Abstract: Many clients and plasma arc thermal cutting devices providers deal with the question which technological factor in adjustment process of cutting has the greatest influence on the final product quality. Many researchers and teachers deal with this issue during lecturing these knowledges for university students. The article presents the design and evaluation of plasma arc cutting technological process. Influence of technological factors on roughness parameters Ra of the steel surface ISO Fe510 have been evaluated using planned experiments. Using factor experiment, the significance of the four process factors: plasma burner feed speed, plasma gas pressure, nozzle diameter, distance between nozzle mouth and material have been observed. Regression models obtained by multiple linear regression indicates the quality level as observed factors function.