• Journal of the Korean Ceramic Society
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• v.34 no.8
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• pp.854-860
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• 1997

The tribological property of ceramics is very important for use in seal rings, pump parts, thread guides and mechanical seal, etc. In the present study, which RBSC/graphite composites were manufactured by adding graphite powders with different particle sizes to mixtures of SiC powder, metallic silicon, carbon black and alumina, effects on the tribological property of each RBSC/graphite composite was investigated in accordance with the particle size of the added graphite powder. The water absorption, the bending strength and the resistance for the friction and wear were measured, and the crystalline phase and the microstructure were respectively examined by using XRD and SEM. In case that the particle size of the graphite powder was fine(2${\mu}{\textrm}{m}$), the formation of $\beta$-SiC was accelerated, thereby making the increase of the bending strength and the decrease of the water absorption, but no improvement for the tribological properties. Furthermore, in case that the particle size of the graphite powder was some large(88~149${\mu}{\textrm}{m}$), the formation of $\beta$-SiC was not accelerated, to thereby make the decrease of the bending strength and the increase of the water absorption, but the improvement for the tribological property of only the composite having the graphite powder of 20 vol%. In addition, in case that the particle size distribution of the graphite powder was large (under 53 ${\mu}{\textrm}{m}$), there was no improvement for every properties. However, the composites, which the graphite powder with the particle size of 53~88 ${\mu}{\textrm}{m}$ was added in 10~15 vol%, had the most increased resistance for the friction and wear which show the worn out amount of 0.4~0.6$\times$10-3 $\textrm{cm}^2$, and the value of the bending strength is 380~520 kg/$\textrm{cm}^2$.

• Tribology and Lubricants
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• v.21 no.6
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• pp.302-305
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• 2005

Various carbon nanotubes (CNTs) are added into the epoxy matrix as reinforcements to investigate the effect on the wear behavior. Effects to the tribological properties of different loading concentrations and types of surface modification are investigated by using a linear reciprocal wear tester. As increasing the concentration of CNTs shows the reduction of the wear loss. Moreover, surface modified CNTs give better tribological property than as produced CNTs. It is due that the functional groups on the surface of CNTs increase the interfacial bonding between CNTs and epoxy matrix through chemical bonding. Changes in worn surface morphology are observed by optical microscope and SEM to investigate the wear behavior. CNTs in the epoxy matrix near the surface are exposed and it becomes the lubricating working film on the worn surface. It reduces the friction and results in the lower surface roughness morphology in the epoxy matrix as increasing the contents of the CNTs.

• Journal of Mechanical Science and Technology
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• v.17 no.12
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• pp.1904-1911
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• 2003

In order to determine the wear properties of AIP (Arc Ion Plating) deposition, wear process was evaluated by using a Falex test machine. Also, in order to determine the effects of coating material on the wear process, TiC, TiN, and TiCN coatings of thickness about 5 $\mu\textrm{m}$∼6 $\mu\textrm{m}$ coated by Arc ion plating deposition method were tested. The wear property was determined under a dry sliding condition as a function of the applied load, sliding distance, sliding velocity and temperature. The results show that when wear of the coating-layer occurred, specific wear amount increased with the wear rate. At initial state, the wear rate rapidly increased, but it gradually reduced as the velocity increased. Also, when raising the temperature, the wear rate increased in the order of TiCN, TiN and TiC due to the frictional heat.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1601-1606
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• 2007

In order for high strength aluminum alloys to be used in transportation systems and the aerospace industry, excellent mechanical and physical properties are required. In particular, excellent anti-abrasion property is indispensable for parts that require driving force. In general, surface treatment technologies such as high frequency heat treatment, gas solid carburizing, surface rolling, shot peening are used as ways of improving anti-abrasion property. Among various surface treatment technologies, this research chose shot peening processing for Al7075-T6, which is well known as representative high-strength alloy steel. Wear characteristics were compared and analyzed after shot peening processing with shot ball velocities of 40m/s and 70m/s in order to investigate the effects of shot peening processing on wear characteristics.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.05a
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• pp.521-522
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• 2010

• Journal of Ocean Engineering and Technology
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• v.23 no.3
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• pp.30-34
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• 2009

Oil hydraulic piston pumps are being extensively used in the world, because of simple design, light weight and effective cost etc. An oil hydraulic pump is likely to have serious problems of high leakage, friction and low energy efficiency according to large time use. In the oil hydraulic piston pumps the clearance between the valve block and piston plays an important role for volumetric and overall efficiency. In this paper, the wear property of the SACM645 material used the hydraulic piston pump has been work out by experimentation with variable heat treatment. To investigate the effect according to the piston surface condition, seven different types specimen were prepared. From the wear test results, induction hardening and nitration were definitely superior to the others. On the whole, nitration was estimated for high strength material to wear resistance.

• Tribology and Lubricants
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• v.10 no.1
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• pp.78-88
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• 1994

For the study of chemical and mechanical properties of the synthetic and mineral oil added with two different Zn-DTPs, base and formulated oils were analyzed and compared. Kinematic viscosity and total acid number (TAN) were tested at high temperature for formulated oils. Also the oils added with different alkyl groups of Zn-DTP were tested for thermal stability and TAN changes. The 4-ball machine was used to test for the mechanical properties, such as the coefficient of friction and wear. The worn areas after sliding test were analyzed with microscope and EDX, too. From the study, mineral and synthetic oil have different effects according to the various added ratio of the primary and secondary alkyl groups of Zn-DTP. Also the temperature of test oil affected the anti-wear and friction property of the formulated oils. For synthetic oil, the primery alkyl group of Zn-DTP made better friction properties than that of secondary, while, for mineral oil, secondary alkyt group was better only at low temperature for mineral oil.

• Korean Journal of Materials Research
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• v.25 no.9
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• pp.442-449
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• 2015

The effects of coating parameters were investigated in wear resistance coatings of Diamalloy-406 on Inconel 718 to obtain an optimum coating condition by high velocity oxy-fuel spraying. The coating parameters, the flow rates of source gases (hydrogen and oxygen), the powder feed rate, and the spray distance, were designed by the Taguchi method. The optimal conditions were determined: oxygen flow rate 34 FRM, hydrogen flow rate 57 FRM, powder feed rate 35 g/min, and spray distance 7 inch. Friction coefficients of the coating and the substrate decreased with an increasing sliding surface temperature from $25^{\circ}C$ to $450^{\circ}C$. The friction coefficient of Diamalloy-4006 coating decreased as the sliding surface temperature increased from $0.43{\pm}0.01$ at $25^{\circ}C$ to $0.29{\pm}0.01$ at $450^{\circ}C$. The wear trace and wear depth of the coating were smaller than the substrate at all temperatures tested. The relationship between spray parameters and wear resistance was discussed extensively, based on the measured roughness, hardness, and porosity in each coating.

• Tribology and Lubricants
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• v.19 no.3
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• pp.151-158
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• 2003

In metal cutting at the tool-chip interface, friction generates considerable amount of heat. Thus, the knowledge of wear properties of cutting tool material in high temperature has been as one of important factors in need of clarification. The authors presented the wear properties of 5%Co-5%V-1%Nb high speed steel, fabricated by powder metallurgy, in room temperature in previous articles. The objective of this paper is to clarify the effects of temperature on its wear properties. Wear tests in sliding conditions under various temperatures have been conducted using the pin-on-disc type wear test machine. The results indicate that the wear properties of 5%Co-5%V-1%Nb high speed steel in high temperature as well as in room temperature are excellent. It may be deduced that the oxide layer formed on worn surface at high temperature is stable enough to prevent wear due to the high temperature strength of its matrix.

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.704-709
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• 2004

The wear behavior and the mechanical property of Cu-$TiB_2$ composites were examined. Cu-$TiB_2$ composites were fabricated by hot extrusion and cold drawing with $TiB_2$ contents(1$\∼$5vol.$\%$) and the size of $TiB_2$ particles(10$\mu$m and 20$\mu$m). The pin-an-disk wear test was carried out under dry sliding wear conditions which loads varied with from 20N to 100N. At the time, counterpart wear material used SM45C. The experimental results showed that the friction coefficient and wear rate decreased with increasing the $TiB_2$ contents and decreasing the size of $TiB_2$ particle. Also, the depth of plastically deformed zone decreased with increasing the $TiB_2$ contents and decreasing the size of $TiB_2$ particle.