• Journal of the korean Society of Automotive Engineers
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• v.15 no.4
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• pp.1-7
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• 1993

최근 엔진의 고성능, 고출력화, 저연비화 Maintenance Free화에 따라 엔진의 부하가 증대되었고, Valve Seat에 대해서도 내마모성, 내열성, 내식성 향상이 요구되고 있다. 특히 무연가솔린과 LPG사용으로 내구성을 갖는 High Performance의 Valve Seat 재질을 요구하게 되었고, 엔진의 높은 작동온도등 가혹한 조건하에서 'Recession'이라 일컬어지는 Seat마모가 생기게 된다. Valve Seat는 일반적으로 분말야금법에 따라 제조되고 있으며, 엔진조건에 따라 여러가지의 재질이 사용되며, 높은 온도에서 열전도성과 기공의 산화방지 및 Valve 내구성 향상의 효과를 얻기 위하여 동용침을 하여 사용하는 추세이다. 본 실험에서는 Valve Seat 기공부위의 산화와 마모특성을 조사하기로 한다.

• 연구논문집
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• s.28
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• pp.101-110
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• 1998

This study discusses the developement of hydraulic rotary actuator design technology for industrial machinery and earthmoving equipment. The lubrication and wear analysis of sliding components of the machinery are very important parameters to strength the design technique. The analysis and wear test are performed for the selected materials of the above mentioned coupled sliding members. The can be used to select the better combinations of sliding components.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2011.05a
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• pp.189-189
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• 2011

CrZrN 박막은 CrN 박막에 비해서 향상된 기계적 특성과 우수한 표면 조도특성을 가지고 있다. 그러나 $500^{\circ}C$ 이상에서 기계적 특성이 급격히 감소하는 현상이 알려져 있다. 본 연구에서는 CrZrN 박막에 Si를 첨가하여 Si 함량에 따른 고온에서의 기계적 특성을 CrZrN 박막과 비교하였다. $500^{\circ}C$에서 마모 실험한 결과 CrZrN 박막에 비하여 소량의 Si의 첨가만으로 고온에서의 마모 특성이 향상되는 것을 확인하였다. 이것은 Si 첨가에 따라 고온에서 안정한 비정질상의 형성 영향으로 판단된다.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.9 no.2
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• pp.231-239
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• 1999

The microstructure of ceramic composite has been found to be governed by the type and amount of the secondary phase, the sintering aid, and the sintering conditions such as sintering temperature, pressure and holing time. Moreover, tribological properties are strongly dependent on microsturcture of composite and operating conditions. In this study, silicon nitride with various amount of magnesia as a sintering aid were prepared and sintered by a hot pressing (HP) technique. Microstructure, mechanical properties (hardness, strength, and fracture toughness), and tribological properties in different environments of $Si_{3}N_{4}$ (in air, water, and paraffine oil) were investigated as a function of MgO content in $Si_{3}N_{4}$. As increasing the amount of MgO in $Si_{3}N_{4}$, the glassy phase in the grain boundaries enlarged the $\beta$-phase elongated grains, and also degraded the Hertzian contact damage resistance. Tribological behaviors in air was seemed to be determined by fracture toughness of $Si_{3}N_{4}$, and those in water and paraffin oil was seemed to be determined by hardness as well as strength. Since glassy grain-boundary phase (MgO) in $Si_{3}N_{4}$ expected to be reacted with water during sliding, such tribochemical reaction reduced wear. In paraffin oil under a higher applied load, the initial sliding dominated wear rate because of Hertzian contact damage.

• The Journal of the Korean dental association
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• v.13 no.12
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• pp.1157-1161
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• 1975

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.11
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• pp.219-225
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• 2020

In this study, the prototype of a blower was designed and made to develop a long-life blower with a volume flow rate of 10,000 ㎥/min with a required total pressure efficiency of 83% or more. Five experimental impellers with various lengths of dust deflectors were manufactured and used for the erosion experiments. The erosion test was conducted by operating for 160 hours in a self-produced closed loop-type erosion test apparatus. A prototype of a model blower was designed, fabricated, and tested. The results revealed a total pressure, air volume flow rate, and efficiency of 690.6 mmAq, 16,243.6 ㎥/min, and 83.6%, respectively, as the result of conversion to a blower based on the measured value of the blower model. The prototype was designed and fabricated as the experimental erosion equipment of the blower. A blower with a dust deflector was developed by performing the erosion experiments under harsh conditions. The blower showed an improved effect of more than 190% based on the wear thickness of the impeller compared to a conventional blower without a dust deflector.

• Journal of the Korean Ceramic Society
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• v.42 no.2 s.273
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• pp.88-93
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• 2005

Ti-AI-Si-N coating layers were deposited on WC-Co substrates by a hybrid system of arc ion plating and sputtering techniques. The coatings were prepared with different Si contents to investigate the effect of Si content on their mechanical properties and microstructures. The dry sliding wear experiments were conducted on Ti-AI-Si-N coated WC-Co discs at constant load, 3N, and sliding speed, 0.1 m/s with two different counterpart materials such as steel ball and zirconia ball using a conventional ball-on-disc sliding wear apparatus. In the case of steel ball, the friction coefficient of Ti-AI-Si-N coating layers became lower than that of Ti-AI­N coating layers. The friction coefficient decreased with increasing of Si content due to adhesive wear behavior between coating layer and steel ball. On the contrary, in the case of zirconia ball, the friction coefficient increased with increasing of Si content, indicating that abrasive wear behavior was more dominant when the coating layers slid against zirconia ball.

• Tribology and Lubricants
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• v.33 no.3
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• pp.98-105
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• 2017

A pin-on-disk test is performed to measure the wear volume of a ductile cast iron (DCI) roll when it wears down using a high carbon steel and two alloy steels at different sliding velocities between the roll and the material (steel). Normal pressure is set as constant and test temperatures are 400, 500 and $600^{\circ}C$. In addition, thermal softening behavior of the DCI roll is examined using a high-temperature micro-hardness tester and the surface hardness variation of the DCI roll is expressed in terms of temperature and heating time. Based on experimental data, a wear coefficient used in Archard's wear model for each material is obtained. The wear volume is clearly observed when the test temperature is $400^{\circ}C$ and sliding velocity varies. However, it is not measured at temperatures of $500^{\circ}C$ and $600^{\circ}C$ even with variations in sliding velocity. From the optical photographs of the pin and disk, the abrasive wear is observed at $400^{\circ}C$ clearly, but no at $500^{\circ}C$ and $600^{\circ}C$. At higher temperatures, the pin surface is not smooth and has many tiny caves distributed on it. It is found that wear volume is dependent on the carbon contents rather than alloy contents. Results also reveal that the variations of wear coefficients are almost linearly proportional to the carbon contents of the material.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.7
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• pp.619-626
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• 2007

The analysis of the frictional energy of the rubber block with contact to the surface is necessary to study the wear for rubber. It is important to define the relationship of the frictional energy and wear, as the most theory of the wear of rubber product is based on the frictional energy of rubber block. To predict the life of the rubber block, the most of research has been focused on the use of the finite element analysis or the actual experiments which need the many time and expensive costs.Therefore, this research is achieved the successful results of the analysis to the frictional energy by analytic method. This frictional energy is function of the material properties, the shape of block, the vertical and horizontal load and the block moving speed. The analytical results are compared with the test results of this paper which can be used for the analysis of the friction behavior for the wear estimation of the rubber products.

• Journal of Periodontal and Implant Science
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• v.34 no.1
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• pp.61-70
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• 2004

연구 목적: 3개월 간의 잇솔질에 따른 칫솔의 마모의 정도와 양상을 관찰하고, 이를 이용한 잇솔질 시의 치태 제거능력의 변화를 평가하여 일반적으로 권장되고 있는 3개월 주기의 칫솔 교체 주기의 근거를 실제 임상적으로 확인해보고자 하였다. 연구방법: 치주적으로 건강한 치과 대학생 52명을 대상으로 설문지를 통해 잇솔질 습관을 조사하고, 치석제거술을 시행하고 실험기간 동안 동일한 칫솔과 치약을 사용하게 하였다. 1주일 후와 2달과 3달째에 구강 내를 erythrosine으로 염색한 후 6개의 Ramfjord 치아의 plaque score를 측정하고, 3달 동안 사용한 칫솔을 수거하여 brushing surface area의 면적으로 마모도를 평가하였다. 결과: 6명이 탈락하였고 전체 부위의 plaque score는 1주 때와 비교하여 2,3 개월의 값이 통계학적으로 유의한 차이가 없었으나, 치간 부위의 plaque score는 3개월의 plaque score와 상관관계는 약하였다. 교체 주기, 잇솔질 횟수, 시간 등의 잇솔질 습관과 마모도의 연관성도 없었지만, 잇솔질 시간과 3개월째의 plaque score의 상관관계는 유의성 있는 결과를 보였다. 결론: 3개월 동안 사용한 칫솔의 치간 부위 치태제거 능력은 감소하였으며, 이의 임상적 영향에 대한 장기간의 연구가 필요하겠다.