• Journal of Biosystems Engineering
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• v.24 no.6
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• pp.473-478
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• 1999

Recently, it is necessary fir surface materials to be low cost and to keep well endurable and wear in machinery field. Since most good materials with endurance and wear are expensive, they are being studied hard to modify to surface materials with endurance and wear, which overlay with the surface membrane completely. One of them is PTA(Plasma Transferred Arc Overlaying Process) method, which gets into the spotlight. It is thought to be an optimum method, since this method of overlays properly materials with about 3∼5cm surface membrane. It is necessity for the modified materials with endurance and wear to improve within the agricultural environment. Therefore, this research was used the PTA method to endure and wear a material. This method proved to be a reliable method for overlaying the membrane on the materials of an economical agricultural machinery.

• Journal of Welding and Joining
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• v.14 no.2
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• pp.28-35
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• 1996

플라즈마에 의한 표면경화법(이하 PTA 육성용접이라고 함)은 개발된 이후 필요한 변수가 너무 많아 오랫동안 폭넓게 적용이 되지 못하고 있었다. 따라서 아주 우수한 코팅 품질을 필요로 하거나 재료측면에서 다른 방법을 사용할 수 없는 경우에 만 적용이 되어왔다. 그리고 경제성보다는 안정성이 우선적으로 보장 되어야 하는 경우, 예를 들면, 핵시설물, 화학설비 또한 엔진설비와 같은 곳에 사용이 되었다. 그 러나 최근에 들어서 특별히 microprocessor와 제어기술의 적용이 적은 비용으로도 가능해지면서 새로운 장치가 개발되었고, 많은 연구에 의하여 코팅의 특성에 미치는 영향을 파악하게 되므로써 PTA 육성용접이 신뢰성이 있으며 다른 육성방법에 비해서 우수한 공정으로 자리를 잡게 되었다. 한편 PTA 육성용접은 낮은 dilution, 좁은 열 영향부 그리고 상대적으로 높은 적층율의 특성이 있어 큰 부피를 코팅하거나 중요한 부품에 적용하기에 적합하다. PTA 장치가 반자동 또는 완전 자동화되면서 상대적으로 운용이 쉬워져 이러한 적용성은 더욱 확대되고 있다. PTA 육성용접은 Table 1에서 보는 바와 같이 다른 표면 경화법에 비하여 투자비용은 많이 들더라도 그 특성에 있 어서는 우수하다고 할 수 있다.

• Journal of Welding and Joining
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• v.15 no.5
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• pp.134-143
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• 1997

The formation of thick alloyed layer with high Si content have been investigated on the surface of Al alloy (A5083) plate by PTA process with Si powder. Hardening characteristics and wear resistance of alloyed layer was examined in relation to the microstructure of alloyed layer. Thick hardened layer in mm-order thickness on the surface of A5083 plate can be formed by PTA process with wide range of process condition by using Si powder as alloying element because of eutectic reaction of Al-Si binary alloy. High temperature and rapid solidification rate of molten pool, which are features of PTA process, enable the formation of high Si content alloyed layer with uniform distribution of fine primary Si paticle. High plasma arc current was beneficial to make the alloyed layer with smooth surface appearance in wide range of powder feeding rate, because enough volume of molten pool was necessary make alloyed layer. Uniform dispersion of fine primary Si particle with about 30${\mu}{\textrm}{m}$ in particle size can be obtained in layer with Si content ranging from 30 to 50 mass %. Hardness of alloyed layer increased with increasing Si content, but increasing rate of hardness differed with macrostructure of alloyed layer. Wear resistance of alloyed layer depended on $V_{si}$(volume fraction of primary Si) and was remarkably improved to two times of base metal at 20-30% $V_{si}$ without cracking, but no more improvement was obtained at larger $V_{si}$.

• Journal of Power System Engineering
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• v.5 no.3
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• pp.88-94
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• 2001

Stellite 12 alloy-powders were overlaid on 410 stainless steel valve seat using plasma transferred arc(PTA) process. Variation of the microstructure, hardness, wear and corrosion of overlaid deposit with current change was investigated. The deposit showed hypoeutectic microstructure, which was consisted of primary cobalt dendrite and networked $M_7C_3$ type eutectic carbides. As current increased, the amount of eutectic carbide decreased and its dendritic secondary arm spacing increased. Hardness of the deposit was decreased with increase of current. Stress relief heat treatment at $600^{\circ}C$ for two hours resulted in slight increase of hardness in the deposit and showed uniform hardness distribution in base metal without any hardened layer in HAZ. Specific wear decreased with increase of sliding distance. The deposit of high hardness with a lot of eutectic carbide showed relatively low specific wear. Initial corrosion current density of the deposit in 0.1N sulfuric acid was lower than those of 410 stainless steel, and showed a little variation with PTA current.

• Journal of Welding and Joining
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• v.11 no.2
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• pp.74-85
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• 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 Advanced Marine Engineering and Technology
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• v.26 no.1
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• pp.68-75
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• 2002

Stellite 12 alloy-powders were overlaid on 410 stainless steel valve seat by plasma transferred arc(PTA)process. Variation of microstructure and hardness of overlaid deposit with aging time at $750^{\circ}C$ was investigated. The deposit showed hypoeutectic microstructure, which was consisting of primary cobalt dendrite and networked $M_{7}C_{3}$type eutectic carbides. After aging new M_{23}C_{6}$ carbide was formed by the partial decomposition of $M_7C_3$ type eutectic carbides and finely dispersed $M_{23}C_6$ type carbides were also precipitated in the matrix. Hardness of the deposit was increased with increase of aging time at $750^{\circ}C$ and showed maximum value at 35hours. After showing maximum value, it was fallen down again at 70hours because of overaging. The increase of hardness in aging is ascribed to the formation of new stable $M_{23}C_6$ type carbide by the partial decomposition of $M_7C_3$ type eutectic carbides and also precipitation of finely dispersed $M_{23}C_6$ carbides in matrix.

• The Journal of Korea CHUNA Manual Medicine
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• v.5 no.1
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• pp.135-139
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• 2004

Objectives : The objectives of this report is to introduce PTA. Methods : The examination of the leg length inequality gives us a useful tool for diagnosis of body imbalance. especially pelvic distortion. There are four steps in the process of the leg analysis, according to "The Standard Manual of Chuna Society (2nd ed., Seoul:KCA Press. 2001)". In the last step of the analysis, knee-flexing over $90^{\circ}$, we have often experienced a specific sign that the lower legs are attracted toward one side spontaneously. The authors call it 'Lower Leg Lateral Attraction'. This is a very significant sign that gives us which is the major part between pelvis and the upper parts over sacrum. Thus it is definded as "Pelvic Twist Analysis, PTA" by the authors. With PTA, first, you must check the side of short leg and next, check the side of lateral attraction in lower leg over-flexing. If both sides coincide with each other, then the major part you can correct first is pelvic distortion. If not, you must find another part for primary correction, instead of pelvis. Conclusions : PTA becomes a useful complement to the examination of the leg length inequality.

• Journal of Welding and Joining
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• v.27 no.3
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• pp.80-84
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• 2009

The Plasma Transferred Arc (PTA) overlay welding method is lately introduced as one of the most useful surface overlay method of the engine component. In this paper, the overlay welding on the SNCrW heat resisting alloy was conducted by the PTA overlay welding process using the super alloy powder. The characteristics of the overlay layers were investigated through the metallurgical and abrasive test. Experimental results showed that the overlay on the SNCrW heat resisting alloy surface was successfully made without hot cracking. The friction wear characteristics of the Co-base Stellite 6 overlayer were most superior. However the abrasive wear characteristics were most inferior in the Co-base Stellite 6 overlayer.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.6 no.2
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• pp.110-115
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• 2005

Plasma Transferred Arc Spray process was used to make modified surface for wear and corrosion resistant by using Co system powder type alloy. The modified surface was produced by changing only spray current and other process variables were constant. The current range was from 80 amp to 140 amp as inclosing 20 amp. It was appeared that the geometrical shape, microstructures and microhardness of the modified surface were affected by the different cooling rate of base metal. The modified surface that produced by 120 amp current exhibited the fine microstructure and the highest microhardness number impling good surface characteristics. It was also found that the spray current affected the width but not the height of the bead as increasing current.

• Journal of Advanced Marine Engineering and Technology
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• v.31 no.7
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• pp.852-856
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• 2007

The Plasma Transferred Arc(PTA) overlay welding method is lately introduced as one of the most useful surface overlay method of the engine component. In this paper, the overlay welding method on the Nimonic super alloy was established by the PTA overlay welding process using the same super alloy powder. The characteristics of the Co-base and Ni-base super alloy overlay layers were investigated through the metallurgical, abrasive and cavitation erosion test. The abrasive and cavitation characteristics were investigated at room and high temperature.