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디스크 경도에 따른 소결마찰재와 내열강 디스크의 마찰ㆍ마모 특성
나선주(Sun Joo Na),박형철(Hyoung Chul Park),김상호(Sang Ho Kim) 한국트라이볼로지학회 2015 한국윤활학회지(윤활학회지) Vol.31 No.2
Because of the growing need for high-speed transport options such as trains and aircraft, there is increasing demand for technology related to high-speed trains. Among them, braking systems are important in highspeed trains in terms of reliability. Especially, the disk brake system, in use in most high-speed trains, transforms kinetic energy into thermal energy and noise. Therefore, the material properties of both the friction materials and disks are expected to influence the tribological characteristics. In this paper, the tribological characteristics depend on the hardness of the brake disks between the Cu-based sintered metallic friction material and the heat-treated heatresisting steel disks. A lab-scale dynamometer used to perform braking tests at a variety of braking speeds using dry conditions. The test results revealed that the hardness of the disks affects the friction coefficients, friction stabilities, and wear rates. Thus, the brake system using the heat-resisting steel disk requires proper heat-treatment. These differences are considered to be caused by the change in tribological mechanisms and the generation of an oxide layer on the friction surfaces. The oxide layers on the friction surfaces are confirmed to Fe₂O₃ by x-ray diffraction (XRD) and scanning electron microscope-energy dispersive spectroscopy (SEM-EDS) analysis.
정은홍 ( Eun Hong Jung ),김은석 ( Eun Suk Kim ),박형철 ( Hyoung Chul Park ),문근배 ( Geun Bae Mun ),장석흔 ( Seok Heun Jang ),김재일 ( Jae Il Kim ),손정환 ( Jung Hwan Son ),하영록 ( Yeong Rok Ha ) 대한외상학회 2009 大韓外傷學會誌 Vol.22 No.2
Renal artery pseudoaneurysm after blunt renal trauma is an uncommon complication of delayed hemorrhage, and diagnostic difficulties are experienced due to its rarity. Delayed hemorrhage after renal trauma is a life-threatening complication. Angiography is considered the gold standard to diagnose a traumatic renal artery pseudoaneurysm. We report here a case of delayed bleeding from a renal artery pseudoaneurysm that was diagnosed at 17 days after the injury and that was managed successfully with selective renal artery embolization without medical complication. (J Korean Soc Traumatol 2009;22:260-263)
정소라(So La Jung),홍의석(Ui Seok Hong),박형철(Hyoung Chul Park),유병관(Byung Kwan Ryu),장호(Ho Jang) 한국트라이볼로지학회 2007 한국트라이볼로지학회 학술대회 Vol.2007 No.11
The friction performance of sintered Friction materials for the high speed train was studied. In this study, newly developed sintered materials based on copper were compared with the commercial products for high speed trains. They were tested on a 1/5 scale dynamometer using low carbon steel disks. Effectiveness, fade, and recovery tests were carried out to examine friction performance and the change of disk thickness variation (DTV) during brake applications and noise propensity were also evaluated. Results showed that the two sintered friction materials exhibit similar friction coefficients and braking performance, whereas the newly developed friction material was superior in terms of DTV generation and noise propensity to the commercial friction material. The improvement of the newly developed friction material was attributed to the high graphite content which reduced the stick-slip phenomena and prevented uneven disk wear by friction films on the counter disk.
무가압 침투법으로 제조된 탄화물 입자 강화 6061 알루미늄 합금 기지 복합재료의 마멸상대재에 따른 미끄럼마멸 거동
박형철,강신철,권훈,김용석 대한금속재료학회 2002 대한금속·재료학회지 Vol.40 No.11
Dry sliding wear tests were carried out on SiC and TiC particle-reinforced 6061 Al alloy matrix composites using different counterpart materials (AISI 52100 bearing steel and alumina) under various loads (1∼12N) and constant sliding velocity (0.2m/sec) conditions. Wear characteristics of the composites against the two counterpart materials were investigated. At low loads (1∼3N), wear rate of composites worn against the steel was lower than that against the alumina. Formation of the MML(Mechanically Mixed Laver) was responsible for the lower wear rate against the steel counterpart. However, at intermediate loads (4∼8N), wear rate of the composites worn against the alumina was lower. Low thermal conductivity of the alumina, which accelerated formation of oxide layers and low adhesive force between the alumina and the matrix alloy were considered to result in the lower rate. At high loads (9∼12N), wear of the composites proceeded by severe deformation of the matrix alloy and subsurface cracking. Wear rates of the composites were similar against the two counterpart materials at the high load regime.
무가압침투법으로 제조된 SiC, TiC, B4C 입자강화 6061 Al 기지 복합재료의 건식 미끄럼 마멸 거동
朴亨哲,姜信哲,權勳,金容奭 대한금속재료학회 2002 대한금속·재료학회지 Vol.40 No.4
Dry sliding wear behavior was investigated in SiC, TiC and B_4C particle reinforced 6061 Al matrix composites that were manufactured by a pressureless infiltration technique. Pin-on-disk wear tests were performed on the composite disk specimen against a hardened AISI 52100 steel ball at various applied loads. Wear resistance of the composites was always higher than that of the monolithic alloy under all test conditions. The resistance increased with the increase of the size and volume fraction of the reinforcing particles. Subsurface deformation and delamination of the deformed (comminuted) layer was a major wear mechanism of the composites at high wear rates, while the composites displayed abrasive-wear-like behavior at low wear rates. Among the composites tested, the SiC reinforced composite showed the lowest wear resistance. Wear resistance of all the composites increased remarkably after T6 heat treatment. Variation of matrix hardness immediately below worn surfaces and the role of surface-iron-oxide layers formed during wear of the composites were also discussed.
탄화물 입자 강화 7075 Al 합금 기지 복합재료의 미끄럼마멸 특성 연구
강석하,박형철,강신철,김용석 국민대학교 생산기술연구소 2002 공학기술논문집 Vol.25 No.-
Effects of the type and volume fraction of carbide-particle-reinforcements on dry sliding wear behavior of 7075 Al alloy matrix composites were investigated. SiC, TiC and B₄C reinforced 7075 Al alloy matrix composites were manufactured by a pressureless infiltration technique and wear tested. Wear tests were carried out using a pin-on-disk wear tester with varying loads of 3N-160N at a constant sliding velocity of 0.2m/s. AISI 52100 bearing steel ball was a counterpart of the composites. Wear resistance of the composites was always higher than that of the monolithic alloy except the TiC reinforced 7075 Al matrix composite. The resistance increased with the increase of volume fraction of the reinforcing particles. Among the composites, the TiC reinforced composite had the lowest wear resistance and the B4C reinforced composite showed the highest wear resistance.