• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2009.10a
• /
• pp.358-361
• /
• 2009

The increasing interest in the surface modification technology by the plasma transferred arc overlaying process in the material processing is placing stringent demands on the manufacturing techniques and performance requirements, and the manufacture employs the high quality and efficiency plasma transferred arc overlaying technology. This paper covers recent technical trends of plasma transferred arc overlaying technology including the COMPENDEX DB analysis.

• The Transactions of the Korean Institute of Electrical Engineers
• /
• v.45 no.3
• /
• pp.415-425
• /
• 1996

This study presents an analytical method of solving the behaviors of arc plasma in a nozzle constricting transferred-type torch and purposes to obtain the basic data for the design of a plasma torch, which can be obtained from the temperature, pressure, velocities and voltage distributions. We have to solve some conservation equations simultaneously and need to know the exact thermal gas properties in order to obtain the correct behaviors of arc plasma. It is also necessary to give the relevant physical or geometric boundary conditions. For the simplicity of analysis, we assumed that (a) the plasma flow is laminar, (b)the local thermodynamic equilibrium, i.e. LTE, prevails over the entire arc column region. The electrode sheath effects were neglected and the nozzle area was excluded from the analysis by assuming that the current flow into the nozzle is zero. We solved the momentum transfer equation including the self-magnetic pinch effect, and obtained the temperature distribution from the energy conservation equation. From this temperature, we could get arc voltage distribution. (author). refs., figs., tabs.

• Journal of Welding and Joining
• /
• v.11 no.2
• /
• pp.74-85
• /
• 1993

Effect of Si metal powders addition with the plasma transferred arc(PTA) overlaying process on characteristics of the alloyed layer in aluminum alloy(A5083) has been investigated. The overlaying conditions were 175-250A in plasma arc current, 500mm/min in travel speed, the 5-20g/min in powder feeding rate. Main results obtained are summarized as follows. 1)Sufficient size of molten pool on surface of base metal was required for forming an alloyed layer; in a fixed travel, the formation of alloyed layer with clear and beautiful surface depend upon the plasma arc current and powder feeding rate; the greater plasma arc current and the smaller powder feeding rate were, the better bead was formed. Optimum alloyed conditions by which an excellent alloyed bead obtained was 225A in plasma arc current. PTA process made it possible to form an alloyed layer with up to 67wt% Si. 2)Microstructure in the alloyed layer was in accord with prediction from the Al-Si phase diagram 3)The hardness of the alloyed layer increased in proportion to Si content. 4)As volume fraction of primary Si increased, the specific wearness of the alloyed layer was significantly improved. However, no further improvement was found when the volume fraction was greater than about 30%. 5)Utilizing the PTA process, a crack free alloyed layer with maximum hardness of about Hv 310 could be obtained.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.6 no.3
• /
• pp.92-97
• /
• 2007

The overlay welding the automobile where the durability is demanded, it is used in the vessel engine valve, plant valve and pump parts. Cause of damage public opinion one what is thought is the fatigue load due to the opening and shutting operation right time repetition of the engine valve. The damage cause of the engine valve or explanation of destruction mechanism is very difficult. The research which it sees to make clear a overlay welding of Co-alloy by Plasma Transferred Arc Weld Surfacing Process reconsideration fatigue crack initiation and fatigue crack growth mechanism at high temperature.

• Journal of the Semiconductor & Display Technology
• /
• v.8 no.4
• /
• pp.89-94
• /
• 2009

The influence on a stability of thermal plasma has been investigated in an electrode structure of non-transferred plasma torch. The variations of dynamic characteristic of the arc voltage was analyzed and compared in terms of voltage character and nozzle types for both the step-shaped nozzles and magnetic-approved cylindrical nozzle. From the experimental results, an electrode gap, flow rate of arc gas, and currents are considered as major operational parameters. As conclusion, it was assured that a torch with step-shaped nozzles of magnetic-approved type produce the stable plasma jet.

• Proceedings of the KWS Conference
• /
• 2001.05a
• /
• pp.245-247
• /
• 2001

In this study, the effects of dilution on the wear behavior of PTAW (Plasma Transferred Arc Welding) Inconel 625, Inconel 718 and Stellite 6 overlays on Nimonic 80A were investigated. Inorder to evaluate the wear performance, two-body and three-body abrasive wear test, and dry sliding wear test were performed. According to wear tests, the wear rate of deposit with dilution 30% was higher than that of dilution 10% by 10%, and it was also found the plastic deformation near worn surface.

• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.52 no.9
• /
• pp.395-399
• /
• 2003

In this paper, physical phenomena which are related to the high temperature and high pressure arc plasma generated during the fault current interruption by SF6 gas circuit breakers are reviewed. In particular, in order to analyze nozzle ablation induced by the heats transferred to the surface of the poly-tetrafluoroethylene(PTFE) nozzle through arc radiation, a governing equation for the calculation of PTFE concentration is added to the governing equations for SF6 arc Plasma analysis. The proposed method is applied to the steady state analysis of $SF_6$ arc plasma generated by direct current taking account of the nozzle ablation and the results are presented.

• Journal of Welding and Joining
• /
• v.17 no.5
• /
• pp.107-115
• /
• 1999

The objective of this research was to study the formation of the thick hardened layer with the addition of metal powder(Cu) and ceramics powders(TiC) on the aluminum 5083 alloys by plasma transferred arc process(PTA process) and to characterize the effect of overlaying conditions on the overlaid layer formation. This was followed by investigating the microstructures of the overlaid layers and mechanical properties such as hardness and wear resistance. The overlaid layer containing copper powder was alloyed and intermetallic compound($CuAl_2$) was formed. The overlaid layers with high melting point TiC powders, however, did not react with base metal. Wear resistance of the alloyed layer was remarkably improved by the formation of $CuAl_2$, precipitate phase, which prevented wear of base aluminum alloys and at higher wear speed, accelerated sliding of the counter part. Wear resistance of the composite layer was also remarkably improved because TiC powder act as a load barring element and Fe debris fragments detached from the counter part act as a solid lubricant on the contact surface.

• Journal of the Korean Society of Industry Convergence
• /
• v.24 no.6_2
• /
• pp.909-917
• /
• 2021

This study was carried out experimentally on the production and properties of silicon nanopowders characteristics using a transferred type arc plasma apparatus. To investigate the properties of silicon nanopowder, the purity of argon gas(99.999%, 99.9%) and the partial pressure ratio of nitrogen gas(0~90%) were varied. The total pressure in chamber is 400Torr and the silicon chunk amount used as raw material is 300g. The power supplied to the cathode to generate arc plasma was 9~12kW/h, and the electrode was made of tungsten and graphite with a diameter of 13mm. The particle size, impurity elements and powder evaporation rate of the silicon powder were analyzed using the XRD, FE-SEM, TEM and electronic scale. According to the purity of argon gas, the silicon evaporation rate and the particle size were similar, and impurities were generated more in the case of 99.9% purity than 99.999%. When argon gas and nitrogen gas were mixed in the chamber, the silicon evaporation rate and particle size increased as the partial pressure ratio of nitrogen gas increased. In particular, when the partial pressure ratio of nitrogen gas was 80%, the silicon evaporation rate 80g/h, and the particle size was about 80~100nm.

• Proceedings of the Korean Nuclear Society Conference
• /
• 1999.10a
• /
• pp.287.2-287
• /
• 1999