• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2001년도 제33회 춘계학술대회 개최
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• pp.115-121
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• 2001

The wear test has been performed to evaluate the wear mechanism of steam generator (SG) tube materials against ferritic stainless steel in water environment. The wear rates of SG tube materials depend on the change of mechanical properties between contact surfaces during wear test. From the subsurface hardness test, Inconel 690 is more work-hardened than Inconel 600 even though these materials have similar hardness values before the wear test. Main cause is due to the difference of stacking fault energy with the chromium content. In water environment, wear mechanism is closely related with the continuous formation and fracture of deformation layers at the contact surfaces.

• Journal of Advanced Marine Engineering and Technology
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• 제24권1호
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• pp.67-74
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• 2000

Recently, PTFE-polymide composites are being used self-lubricating parts for industrial field. Thus, this study is mainly concerned with friction and wear properties for the piston ring of non-lubricating air compressor which made of PTFE-polymide composites. The friction and wear test was carried out for the different composition ratio under the atomsphere room temperature and constant load of 7.69N and their friction and wear properties were compared with each other at various sliding speed. notable results are summarized as follows. PTFE 100% showed that friction coefficient was almost same values at 0.94 and 1.88m/s but the value was decreased at 2.83m/s because the friction temperature is higher than low speed. PTFE 80%-PI 20% showed the lowest mean friction coefficient at 2.83m/s. PTFE 20-PI 80% showed the highest friction coefficient at 0.94m/s and the value was decreased at high speed but the value is higher than other materials except PTFE 100 %. PI 100% showed the highest friction coefficient at 0.94 and 1.88m/s becuase adhesive wear mainly occurred that speed. PTFE 100% showed highest specific wear rate on the whole. Specific wear rate of PTFE 80%-PI 20% was almost the same value with PTFE 20%-PI80%. PI 100%showed the lowest value at high sliding speed because the friction surface was thicken and carbonated by high friction temperature.

• 한국정밀공학회지
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• 제21권10호
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• pp.180-187
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• 2004

Die design to minimize the die wear in the cold forging process is very important as it reduce the production cost and the increase of the production rate. The quantitative estimation fur the die wear is too hard because the die wear is caused by many process variables. So, in this paper, the optimal shape of the backward extrusion punch is newly designed through the FE-analysis considering the surface expansion and Archard wear model in order to reduce the rapid wear rate that is generated for the backward extruded products exceeding the forming limit. The main shape variables of the backward extrusion punch are the flat diameter, angle, and round of the punch nose part. As the flat diameter and angle of the punch nose are larger, the surface expansion is reduced and the wear rate is decreased according to the reduction of the punch round. These results obtained through this study can be applied to the real manufacturing process.

• 한국주조공학회지
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• 제28권3호
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• pp.119-123
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• 2008

Wear test on two die steels for aluminum die casting was carried out by dipping and rotating the specimens into the molten aluminum maintained $680^{\circ}C{\sim}780^{\circ}C$. The rotating speed of the specimen was $4.5rpm{\sim}20.0rpm$. Diffusion layer was formed between the die steel and molten aluminum, and became thicker with dipping time. Wear rate was not proportional with the thickness of the diffusion layer, but was closely related to the density of the diffusion layer. Wear rate was little affected by the kind of die steel and by the microstructure such as martensite, tempered martensite, and pearlite. Specimen with nitrided surface showed good wear resistance, and its wear rate was decreased with increase in the thickness of nitrided layer. While whole surface was worn in heat treated specimens, wear of nitrided specimens was proceeded by pitting partially.

• 한국철도학회논문집
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• 제20권4호
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• pp.512-520
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• 2017

일반적인 철도에서는 차륜과 레일의 마찰력을 이용하여 열차가 주행하게 된다. 차륜과 레일 사이에는 접촉압력이 발생하게 되고, 차량의 중량, 속도, 사행동, 접촉점 등에 따라 접촉압력의 크기가 변화하게 된다. 본 연구에서는 곡선부 차륜/레일에 대한 유한요소해석을 통해 접촉특성을 분석하였으며, 구름접촉피로시험을 통해 접촉압력에 따른 차륜/레일의 피로손상 및 마모율을 분석하였다. 구름접촉피로시험결과, 일반 및 열처리레일은 차륜에 비해 마모율이 높았으며, 일반 및 열처리레일마모율은 일정한 반복횟수 이상에서 급격히 증가하는 것으로 분석되었다. 또한, 일반레일이 열처리레일 보다 약 7~15% 마모율이 높았으며, 접촉압력 900~1,500MPa 범위에서 접촉압력에 따른 레일마모율에 대한 회귀분석식을 제시하였다.

• 대한기계학회논문집A
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• 제33권12호
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• pp.1383-1392
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• 2009

A disadvantage in the design of a hypotrochoidal gear pump as in a gerotor pump is a lack of parts that can be adjusted to compensate for wear in the rotor set, and as a consequence, it causes a sharp reduction of volumetric efficiency. In this paper, an attempt has been made to reduce the wear rate between the rotors of a hypotrochoidal gear pump. Using the knowledge of shape design on the rotors, the contact stresses without hydrodynamic effect between the rotors' teeth are evaluated through the calculation of the Hertzian contact stress. Based on the above result and the sliding velocity between the rotors, a genetic algorithm (GA) is used as an optimization technique for minimizing the wear rate proportional factor (WRPF). The result shows that the wear rate or the WRPF can be reduced considerably, e.g. approximately 12.8% in this paper, throughout the optimization using GA.

• Tribology and Lubricants
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• 제12권1호
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• pp.56-65
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• 1996

The result of wear test for ceramic materials was assessed by Scf parameter to verify the usefulness of the proposed Scf parameter. Friction and wear tests were carried out with ball on disk type. The materials used in this study were HIPed Alumina $(Al_2O_3)$, Silicon carbide (sic), Silicon nitride $(Si_3N_4)$ and Zirconia $(ZrO_2)$. The tests were carried out at room temperature with self mated couples of ceramic materials under lubricated condition. Turbine oil was used as a lubricant. In this test, increasing the load, specific wear rates and wear coefficients of four kinds of ceramic materials had a tendency to increase. The wear coefficients of ceramic materials were in order of $Al_2O_3, SiC, Si_3N_4, ZrO_2$. Worn surfaces investigated by SEM had residual surface cracks and wear particles caused by brittle fracture. As the fracture toughness of ceramic materials was higher, wear resistance more increased. The roughness of worn surface had correlation with wear rate. The wear rate(W$_{s}$) and Scf parameter showed linear relationship in log-log coordinates and the wear equation was given as $W_s = 5.52 $\times$ Scf^{5.01}$.

• 대한기계학회논문집
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• 제17권6호
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• pp.1441-1455
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• 1993

본 연구에서는 최신기법에 의해서 제조된 HIP제 질화규소와 지르코니아를 실험재료로 하여 무윤활하에서의 미끄럼마찰·마멸실험을 수행하여 마찰·마멸특성을 규명하고, SEM을 이용한 마멸면의 미시적 관찰을 통해서 세라믹의 마멸기구를 조사하 여 세라믹마멸기구의 마멸모델을 제시하고자 한다. 제시된 마멸모델에서 파괴역학을 도입하여 이론해석과 고찰을 수행하여 보다 실용적인 세라믹의 마멸율울 평가할 수 있 는 새로운 무차원 파라메터를 제안하고자 한다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 춘계학술대회 논문집
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• pp.560-567
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• 2011

Wheel and rail wear is a fundamental and complicate problem in railway field. The life of railway is usually limited by wear. The wheel surface is subjected to high normal and tangential contact stress. The removal of material from the surface by wear is function of the sliding and contact stress. In the present paper, the wear characteristic depended on slip rate, contact pressure and temperature are investigated and is used to twin disc tester. The result shows that the wear in wheel-rail interface is remarkably depended on slip rate and contact pressure.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.1000-1007
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• 2011

Wheel and rail wear is a fundamental and complicate problem in railway field. The life of railway is usually limited by wear. The wheel surface is subjected to high normal and tangential contact stress. The removal of material from the surface by wear is function of the sliding and contact stress. In the present paper, the wear characteristic depended on slip rate, contact pressure and temperature are investigated and is used to twin disc tester. The result shows that the wear in wheel-rail interface is remarkably depended on slip rate and contact pressure.