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0.2% C강의 미세조직에 따른 3-body 연삭마멸 특성 연구
윤나래(N. R. Yoon),김종철(J. C. Kim),정영중(J. -Y. Jeong),권혁우(H. W. Gwon),김용석(Y. -S. Kim) 한국소성가공학회 2011 한국소성가공학회 학술대회 논문집 Vol.2011 No.5
Abrasive wear behavior of 0.2 wt. % C steel with different microstructures was studied. The steel was heat treated to obtain various microstructures under different conditions. Three-body abrasive wear tests were carried out using a ball-cratering abrasive wear tester at fixed load of 0.2 N. Sliding speed and wear distance adopted were 0.05 m/sec and 50 m, respectively. A bearing steel ball was utilized as a counterpart. SiC particles of size approximately 4 ㎛ were used as the abrasive medium. The slurry concentration and feed rate were 0.75 g/ml and 1.15 g/min, respectively. The wear crater was examined using SEM, FESEM, and a surface profilometer to investigate the wear mechanism of the steel. It was found that the abrasive wear resistance was proportional to initial hardness of the heat treated steel.
0.25% C 저합금강 합금원소 변동에 따른 미세조직과 가공경화능의 변화가 미끄럼 마멸거동에 미치는 영향
김종철(J. C. Kim),정영중(Y. J. Jung),김용석(Y.-S. Kim),H. W. Kwon,N. R. Yoon 한국소성가공학회 2011 한국소성가공학회 학술대회 논문집 Vol.2011 No.10
The aim of this investigation is to find out the effect of microstructure and work-hardening capacity varied by alloying element on the sliding wear of 0.25 wt % C low alloy steel. To examine the effect of microstructure and work-hardening capacity, 5 kinds of steels were fabricated by changing the contents of Mn, Cr and B in the 0.25C steel. Dry sliding wear tests were carried out using a pin-on-disk wear tester at the constant load of 100 N and sliding speed of 0.1 m/s. Of all the specimens Mn, Cr and B added steels showed high wear resistance compared with the other steels. Wear resistance of the steel increased significantly when both Cr and B are added simultaneously to the steel. The high wear-resistance of the steels with B and Cr were attributed to their highter work-hardening capacity during the wear.
0.25 wt.% C 저합금강의 미끄럼 마멸거동에 미치는 합금원소의 영향
김종철(J. C. Kim),윤나래(N. R. Yoon),김용석(Y. S. Kim) 한국소성가공학회 2011 한국소성가공학회 학술대회 논문집 Vol.2011 No.5
The purpose of this study is to investigate the effect of alloying elements on dry sliding wear behavior of the 0.25 wt. % C low-alloy steel. To examine the effect of alloying elements, 11 kinds of steels were fabricated by varying the amount of Cr, B and Ti. Dry sliding wear tests have been carried out using a pin-on-disk wear tester at the constant load of 100 N and sliding speed of 0.1 m/s. Of all the specimens Cr, B and Ti alloyed steels showed high wear resistance compared with the other steels. The higher wear resistance of the steels were attributed to their higher dynamic strain-hardening capacity during the wear.
0.3wt.%C 탄소강의 미세조직과 3-body 연삭마멸 거동 사이의 상관관계
정영중(Y. -J. Jeong),김종철(J. C. Kim),권혁우(H. Gwon),김용석(Y. -S. Kim) 한국소성가공학회 2012 한국소성가공학회 학술대회 논문집 Vol.2012 No.5
The present investigation was performed to find out the relationship between 3-body abrasive wear characteristics and microstructure in a 0.3 wt.% C steel. The steel was heat treated under different conditions to have PF/P (Polygonal ferrite & Pearlite), B (Bainite), M (Martensite) and TM (Tempered martensite) microstructures. Three-body abrasive wear tests were carried out using a ball-cratering tester. The tester used AISI 52100 steel ball as a counterpart. The ball-surface was roughened prior to the test, which was necessary for smooth feeding of abrasive slurry into the contact between the ball and the specimen. The slurry was composed of Al₂O₃ particles (4㎛) suspended in water with a concentration of 0.75g/ml. The slurry was fed on top of the ball throughout the test at an approximate rate of 1.445g/min. All tests were performed at a normal load of 0.2 N, sliding (ball rotation) speed of 0.1m/s and sliding distance of 50m. Microstructure of the heat treated specimens was observed by an optical microscope, and the worn surfaces were observed by a stereoscopic optical microscope and SEM (scanning electron microscope). The M (martensite) specimen showed the highest 3-body abrasive wear resistance due to its much higher hardness than the others. Among the specimens with similar hardness, the PF/P (polygonal ferrite/pearlite) specimen displayed high wear resistance, where the wear proceeded by a ploughing mechanism.
배터리와 슈퍼 캐패시터를 가지는 직렬형 하이브리드 차량의 전력 제어 방법 비교
김종철(J. C. Kim),이성준(S. J. Lee),조보형(B. H. Cho) 전력전자학회 2010 전력전자학술대회 논문집 Vol.2010 No.7
하이브리드 자동차는 주 에너지원 외에 보조 에너지 저장 장치를 가지게 되는데 배터리와 슈퍼 캐패시터를 혼합하여 사용 할 경우 주행 성능이 향상된다. 하지만 배터리의 경우 잦은 충방전이 일어날 경우 수명이 감소되고, 큰 전류에 의해 손상된다는 단점이 있다. 반면 슈퍼 캐패시터는 충방전 횟수가 많고, 수명이 길다는 장점이 있다. 따라서 배터리의 사용을 최소로 하고, 슈퍼 캐패시터를 주로 사용하여 제어 할 경우, 배터리의 수명 향상을 기대할 수 있다.