• International Journal of Precision Engineering and Manufacturing
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• 제5권2호
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• pp.39-45
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• 2004

Atomic Force Microscope (AFM) has been widely used in micro/nano-scale studies and applications for the last few decades. In this work, wear characteristics of silicon-based AFM tip was investigated. AFM tip shape was observed using a high resolution SEM and the wear coefficient was approximately calculated based on Archard's wear equation. It was shown that the wear coefficient of Si and ${Si}_3$$N_4$ tips were in the range of ${10}^{-1}$~${10}^{-3}$and ${10}^{-3}$~${10}^{-4}$, respectively. Also, the effect of relative humidity and sliding distance on adhesion-induced tip wear was investigated. It was found that the tip wear has more severe for harder counter surface materials. Finally, the probable wear mechanism was analyzed from the adhesive and abrasive interaction point of view.

• 동력기계공학회지
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• 제18권6호
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• pp.174-179
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• 2014

The wear behavior of epoxy matrix composites filled with nano sized silica particles is discussed in this paper. Especially, the variation of the coefficient of friction and the specific wear rate under the various applied load and sliding velocity were investigated for these materials. Wear tests of pin-on-disc mode were carried out and followed by scanning electron microscope observations. The presence of silica filler in epoxy composites was demonstrated significant influence on the friction and wear behavior of epoxy nanocomposites. With the incorporation of silica filler into the epoxy matrix, reduction of the coefficient of friction and specific wear rate were identified. Wear mechanism was discussed by analyzing the worn surface by scanning electron microscope as well.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 하계학술발표대회 논문집
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• pp.189-193
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• 2008

Performance of refrigerant oil at the thrust-bearing and at the journal-bearing of a scroll compressor is a significant factor. This paper presents the friction and anti-wear characteristics of nano oil with a mixture of a refrigerant oil and carbon nano particles in the journal bearing of scroll compressors. The characteristics of friction and anti-wear using nano-oil is evaluated using the disk on disk tester and the journal bearing tester for measuring friction surface temperature and the coefficient of friction at the journal bearing tester. In journal bearing test, the average friction coefficient of high concentration nano-oil was decreased down to 18% compared to raw oil under 4,500 N and 3,600 rpm. It is believed that nano particles can be coated on the wear surfaces and the interaction of nano particles between surfaces can be improved the lubrication in the friction surfaces. Worn surfaces of frictional specimen were measured with straightness. carbon nano oil enhances the characteristics of the anti-wear and friction at the joural bearing of scroll compressors.

• Corrosion Science and Technology
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• 제6권4호
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• pp.159-163
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• 2007

Micron size Co-alloy 800 (T800) powder is coated on the high temperature, oxidation and corrosion resistant super alloy Inconel 718 substrate by the optimal high velocity oxy-fuel (HVOF) thermal spray coating process developed by this laboratory. For the study of durability improvement of high speed spindle operating without lubricants, friction and sliding wear behaviors of the coatings are investigated both at room and at an elevated temperature of $1000^{\circ}F(538^{\circ}C)$. Friction coefficients, wear traces and wear debris of coatings are drastically reduced compared to those of non-coated surface of Inconel 718 substrate both at room temperature and at $538^{\circ}C$. Friction coefficients and wear traces of both coated and non-coated surfaces are drastically reduced at higher temperature of $538^{\circ}C$ compared with those at room temperature. At high temperature, the brittle oxides such as CoO, $Co_{3}O_{4}$, $MoO_2$ and $MoO_3$ are formed rapidly on the sliding surfaces, and the brittle oxide phases are easily attrited by reciprocating slides at high temperature through oxidation and abrasive wear mechanisms. The brittle solid oxide particles, softens, melts and partial-melts play roles as solid and liquid lubricants reducing friction coefficient and wear. These show that the coating is highly recommendable for the durability improvement coating on the machine component surfaces vulnerable to frictional heat and wear.

• 설비공학논문집
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• 제21권10호
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• pp.559-563
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• 2009

Performance of refrigerant oil at the thrust-bearing and at the journal-bearing of a scroll compressor is a significant factor. This paper presents the friction and anti-wear characteristics of nano oil with a mixture of a refrigerant oil and carbon nano particles. The characteristics of friction and anti-wear using nano-oil is evaluated using the disk on disk tester for measuring friction surface temperature and the coefficient of friction. The average friction coefficient of nano-oil was reduced by 60% compared to raw oil under 600 N and 1,000 rpm. It is believed that the interaction of nano particles between surfaces can be improved the lubrication in the friction surfaces. Worn surfaces of frictional specimen were also investigated by the optical and atomic force microscopy. Conclusively, it is expected that wear and friction coefficient of compressor can be reduced by alignment applying nano-oil as refrigerant oil.

• Tribology and Lubricants
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• 제39권3호
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• pp.111-117
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• 2023

This paper presents an experimental investigation of the tribological characteristics of PTFE composites filled with nano CuO particles under low sliding speed and load. All the specimens were prepared by sintering. Before sintering, the mixture of PTFE powder and CuO particles were mixed by a high-speed mixer using CuO volume fractions of 0.2 vol. % and 5 vol. %. Each mixture was sintered at 350 ℃ for 30 min on the steel disk. We conducted ball-on-disk sliding test an hour using a steel ball against PTFE composites, including pure PTFE. The load and sliding speed used was 2 N and 0.01 m/s, respectively. Adding nano CuO particles increases the friction coefficient because of the abrasiveness of hard nano CuO particles. The highest coefficient of frictions was obtained from 5 vol. % CuO. Conversely, the lowest wear of the composites was obtained from the 5 vol. % CuO nanocomposite. This study reveals that the addition of nano CuO particles can lower the wear of PTFE, despite an increase in the coefficient of friction. However, the coefficient friction is still moderate compared to other engineering polymers. In addition, the amount of CuO nano particles has to be optimized to reduce friction and wear at the same time.

• 한국분말재료학회지
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• 제8권3호
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• pp.210-213
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• 2001

$Si_3N_4$/TiN nano/nano-type composites were successfully fabricated by the combination of a mechano-chemical grinding (MCG) method and a short time sintering process, and their wear resistance was evaluated. Powder mixtures of $\alpha-Si_3N_4$and Ti were prepared using mechano-chemical grinding process and the resulting nanocomposite powder mixtures were consolidated using pulsed electric current sintering (PECS). TEM observation showed that the nano/nano-type composites consisted of homogeneous and very fine matrix grains with the size less than 100 nm. The obtained $Si_3N_4$-based nano/nano-type showed high wear resistance and electric discharge machinability.

• 수산해양기술연구
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• 제49권4호
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• pp.492-499
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• 2013

The characteristics of abrasive wear of the rubber matrix composites filled with nano sized silica particles were investigated at ambient temperature by pin-on-disc friction test. The range of volume fraction of silica particles tested are between 11% to 25%. The cumulative wear volume and friction coefficient of these materials on particle volume fraction were determined experimentally. The major failure mechanisms were lapping layers, deformation of matrix, ploughing, deboding of particles and microcracking by scanning electric microscopy photograph of the tested surface. The cumulative wear volume showed a tendency to increase nonlinear with increase of sliding distance. As increasing the silica particles of these composites indicated higher friction coefficient.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part2
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• pp.964-965
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• 2006

The injection molded Fe sintered bodies were fabricated using two kinds of nano Fe powders, $Fe-5%vol.ZrO_2$ and $Fe-10vol.%ZrO_2$ powders. The relationship between microstructure and mechanical properties depending on the $ZrO_2$ contents and sintering temperature were characterized by SEM and TEM techniques. In the wear test, the $Fe-0vol%ZrO_2$ sintered bodies showed mainly adhesive wear, but in the Fe-5%vol. $ZrO_2$ and Fe-10vol. % $ZrO_2$ composites the main wear behavior showed abrasive wear mode.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2014년도 추계학술대회 논문집
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• pp.180-181
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• 2014

Optically translucent Sialon ceramics was fabricated by hot pressed sintering method. The Sialon ceramics was laser textured and their tribological performance was observed. Starved lubrication method was applied on Sialon ceramics with different dimple spacing under a load of 10N and at room temperature. The material having high dimple spacing ($200{\mu}m$) shows low coefficient of friction. The material shows mild wear and therefore, wear rate of steel ball (meeting partner) was observed to measure wear rate. Different phases Sialon ceramics were analyzed by XRD patterns. Moreover, the mechanical properties of the Sialon ceramics were observed.