• 한국레이저가공학회지
• /
• 제7권2호
• /
• pp.27-38
• /
• 2004

Laser remelting of surface of cobalt-based hardfacing alloy can eliminate impurities and cracks and improve the wear resistance. In this present study, Stellite ${\sharp}6\;and\;{\sharp}21$ harfacing alloys were remelted by a 3kW CO2 laser. Hardness distribution and microstructures in the laser remelted zone was investigated. Our results showed that in proper laser parameters laser remelted surface of hardfacing alloy had more refined microstructure and more increased micro-hardness than the base material.

• KSBB Journal
• /
• 제4권3호
• /
• pp.208-214
• /
• 1989

필드 하드웨어와 소프트웨어를 자체 개발하고 컴퓨터 인터페이싱을 수행하여 유전 재조합세포 발효 공정을 온.라인으로 휘드.백 및 휘드.포워드 식 자동제어 할 수 있었다. 유전자 재조합 세포들이 발현을 위하여 온도 유도 및 화학약품 유도 방법을 사용하였다. 빠르고 안정된 반응을 보이고 정확한 자동 제어를 수행할 수 있었다.

• 한국재료학회지
• /
• 제13권12호
• /
• pp.839-845
• /
• 2003

The abrasion and impact wear resistance were investigated on the hardfacing weld dispersed with the recycled hard metal(HM). The HM was composed of the tungsten carbide(WC) reinforced metal matrix composite. The cored wire filled with the 25-35wt.% HM and 2-8wt.% of the alloying element, Fe-75Mn- 7C(FeMnC), was used for the gas metal arc(GMA) welding. By using the cored wire of the 25wt.% HM and FeMnC addition, the weld showed mostly constant wear loss for the abrasion as a function of the FeMnC content. This was due to the insufficient amount of the tungsten carbide formed during the GMA welding. The FeMnC addition to the 35wt.% HM did not improve the abrasion wear property since the amount of the tungsten carbide formed was decreased with respect to the FeMnC amount. The 6wt.% FeMnC addition to the 35wt.% HM exhibited the better impact wear resistance than the hardfacing weld by 40wt.% HM.

• 터널과지하공간
• /
• 제25권6호
• /
• pp.496-504
• /
• 2015

로드헤더는 커팅헤드에 픽커터를 설치하여 지반을 굴착하는 장비이다. 픽커터는 일반적으로 코니컬타입을 사용하며, 코니컬 픽커터는 선단부에 마모에 강한 텅스텐카바이드 팁을 사용하여 커터의 소모를 감소시키는 굴착 도구이다. 본 연구에서는 구리광산의 망토와 역암으로 구성된 복합지반을 대상으로 로드헤더 커팅헤드에 3종류의 코니컬 픽커터를 사용하여 내구성능을 살펴보았다. 현장적용 후, 픽커터의 육안조사와 중량감소율 측정, 그리고 CT 및 SEM을 이용한 내 외부 균열조사를 수행한 결과, 하드페이싱으로 보강한 코니컬 픽커터의 내구성능이 가장 우수하였으며, 각 코니컬 픽커터의 내 외부에서는 현장적용 전과 후 모두에서 매크로 크랙 및 미세균열을 발견할 수 없었다.

• Journal of Welding and Joining
• /
• 제25권5호
• /
• pp.58-63
• /
• 2007

The relationship between GMA welding conditions and the bead shape of overlay weld was studied by using ${\Phi}1.6mm$ hypo-eutectic metal-cored wire designed for hardfacing against the severe metal-to-metal wear. As the welding voltage increased, the dilution also increased but the sudden drop of dilution was observed at $30{\sim}33V$. It was considered to be due to the decrease of penetration resulting from the change of transfer mode, from short circuit to spray. It was also found that the behavior of penetration with welding current was dependant on the transfer mode. The short circuit mode exerted the penetration to decrease while the spray mode did it to increase with increase of welding current. The former was considered to be responsible for the remarkable decrease in dilution at low welding voltage region. The change of transfer mode also had an effect on the behavior of bead width with welding current but it did not on the bead spreadability defined as W/H ratio. It was considered that the optimal welding conditions for multi-pass overlay welding could be obtained from the bead spreadability suitable for bead lapping and the dilution as low as possible in the spray transfer mode.

• 한국재료학회지
• /
• 제32권10호
• /
• pp.442-447
• /
• 2022

Sealing treatment is a post-surface treatment of the plasma spray coating process to improve the corrosion resistance of the coating material. In this study, the effect of the sealing on the corrosion resistance and adhesive strength of the plasma spray-coated alumina coatings was analyzed. For sealing, an epoxy resin was applied to the surface of the coated specimen using a brush. The coated specimen was subjected to a salt spray test for up to 48 hours and microstructural analysis revealed that corrosion in the coating layer/base material interface was suppressed due to the resin sealing. Measurement of the adhesive strength of the specimens subjected to the salt spray test indicated that the adhesive strength of the sealed specimens remained higher than that of the unsealed specimens. In conclusion, the resin sealing treatment for the plasma spray-coated alumina coatings is an effective method for suppressing corrosion in the coating layer/base material interface and maintaining high adhesive strength.