• Journal of Welding and Joining
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• v.17 no.5
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• pp.107-115
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• 1999

The objective of this research was to study the formation of the thick hardened layer with the addition of metal powder(Cu) and ceramics powders(TiC) on the aluminum 5083 alloys by plasma transferred arc process(PTA process) and to characterize the effect of overlaying conditions on the overlaid layer formation. This was followed by investigating the microstructures of the overlaid layers and mechanical properties such as hardness and wear resistance. The overlaid layer containing copper powder was alloyed and intermetallic compound($CuAl_2$) was formed. The overlaid layers with high melting point TiC powders, however, did not react with base metal. Wear resistance of the alloyed layer was remarkably improved by the formation of $CuAl_2$, precipitate phase, which prevented wear of base aluminum alloys and at higher wear speed, accelerated sliding of the counter part. Wear resistance of the composite layer was also remarkably improved because TiC powder act as a load barring element and Fe debris fragments detached from the counter part act as a solid lubricant on the contact surface.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2003.11a
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• pp.360-367
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• 2003

Diamond-like carbon(DLC) films are considerable research interest because of their widespread applications as protective coatings in areas such as optical windows, magnetic storage disks, car parts, biomedical coatings and as micro-electromechanical devices(MEMs). DLC films were deposited on WC-Co by PECVD using Ar, $C_2H_4$ gas. Tribological tests were conducted using a ball-on-disk type tribometer in dry air. Three kinds of counter-bodies balls were used. The counter-bodies balls are SM45C, SUJ2 and $ZrO_2$(3.17mm in diameter). Wear rate of the samples were calculated after measuring the worn-out volume of the wear track. As results wear test, the higher hardness of counter-bodies, friction coefficient low. As result of XPS estimation, wear debris generated as an oxide lower the friction coefficient.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2001.11a
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• pp.69-77
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• 2001

Wear and Friction characteristics of plasma-sprayed Cr$_2$O$_3$ coating and Cr$_2$O$_3$ coating included SiO$_2$ and TiO$_2$ against SiC ball have been investigated under different loads. Worn surfaces were observed by SEM and worn surfaces were analyzed by EDS. The Friction coefficient and the Wear resistance of Cr$_2$O$_3$-5SiO$_2$-3TiO$_2$coating was less than that of Cr$_2$O$_3$ coating. The main mechanisms were plastic deformation and brittle fracture. The film on surface were made by plastic deformation and compacted wear debris. This film protect wear of coating

• Journal of Powder Materials
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• v.7 no.1
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• pp.12-18
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• 2000

Effects of the microstrucrure of rapidy solidified Al-Pb-Cu-Mg alloys on the wear investigated. In order to overcome the miscility gap between Al and pb under equilibrium conditions, both in the solid and the liquid states, the alloy were rapidy solidifies to produce them in a segregation-free condition. Although the Pb particles showed relatively fine dispersion in the Al matrix in all the alloys by this process. the Al-16Pb alloy was found to have the most favorable microstructure with discretre with discrete Pb particles of abount 0.5 ${\mu}$m in size. With the addition of Cu and Cu-Mg to Al-16Pb, cellular structures were newly formed; not seen in the binary Al-Pb alloy. Wear properties of the Al-Pb binary alloys measured as a function of the sliding speen, sliding distance, and applied load showed that the Al-16Pb alloy has the best wear resistance, as expected from the fine microstructural features in this alloy. The were resistance of the alloy containing Cu-and Cu-Mg was higher than that of the Al-16Pvb alloy, due to matrix strengthening by precipitation hardeing. The wear mechanism was identified by examining the traces and wear debris.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.1
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• pp.21-30
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• 2017

The surface temperature of disc brakes varies during braking, which can affect the friction and wear behavior of braking systems. In order to develop an efficient braking system, the friction and wear behaviors of brake materials need to be clearly understood. In this work, the friction and wear behavior of the C/C-SiC-Cu composite and the Al/SiC composite, which are used in disc braking systems, were investigated. Both the surface temperature and contact pressure were studied. A pin-on-reciprocating tribotester was used for this purpose, in order to control temperature and load. Results showed that the friction varied significantly with temperature and sliding distance. It was found that a transfer layer of compacted wear debris formed on the wear track of the two materials. These layers caused the surface roughness of the wear track to increase. The outcome of this work is expected to serve as a basis for the development of braking systems under various operating conditions.

• Transactions of the Korean Society of Mechanical Engineers
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• v.13 no.3
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• pp.404-410
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• 1989

Friction and wear tests were conducted with several different ceramics sliding against ceramic and metal couples with and without lubricant in a two disk type sliding machine. The purpose was to know the tribological properties of ceramics. With very different physical and chemical properties of ceramics compared to metal, the tribological properties of ceramics should be defined in detail. Among them, the wear and friction with same or different couple is very important. Also the lubrication of ceramic is one of the major area to be studied. From this research, SiC, SI$_{3}$N$_{4}$ and ZrO$_{2}$ were slid against SiC, AISI 4340 and bronze under various sliding condition. It was found that the friction and wear of ceramics are strongly dependent on the sliding condition. For unlubricated sliding against SiC, ZrO$_{2}$ shows low wear and friction coefficient over wide lange of load, but with lubricated sliding, SiC shows better performance whatever lubricants were used. Also the effect of lubricant depended upon the material properties of sliding pairs. The general tribological properties of ceramics were not correlated with chattering and noise at low load but it could be reduced or avoided effectively by using lubricants. SiC and Si$_{3}$N$_{4}$ slid against SiC have transition from mild to severe wear at high load but ZrO$_{2}$-SiC and SiC-steel have not. Wear debris formed on the contact area of SiC couples was main cause of the initiation of transition. At high speed, only ZrO$_{2}$ sliding against SiC has transition of wear by low thermal conductivity.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.5
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• pp.791-799
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• 1997

The wear characteristics and wear mechanisms of plasma sprayed Al/sub 2/ O/sub 3/-40%TiO/sub 2/ and Cr/sub 2/O/sub 3/ deposited on casting aluminum alloy(AC4C) were investigated. Specimens were processed for various coating thicknesses. Ball on disk type wear tester was used for wear test. The scratch test on plasma sprayed coating surface showed that critical load to break the coating layer was greater than 40 N. The critical load increase with the increase of coating thickness of specimens. The friction coefficient of Cr/sub 2/O/sub 3/ coating layer was less than that of Al/sub 2/O/sub 3/-40%TiO/sub 2/ coating layer. The wear resistance of Cr/sub 2/O/sub 3/ coating layer was greater than that of Al/sub 2/O/sub 3/-40%TiO/sub 2/ coating layer. Microscopic observation of worn surfaces was made by SEM. SEM observation showed that the main mechanism of wear for Al/sub 2/O/sub 3/-40%TiO/sub 2/ coating layer was abrasive wear under 50 N. For the case of Al/sub 2/O/sub 3/-40%TiO/sub 2/ coating layer, as the surface cracks perpendicular to sliding direction propagated, the wear debris was generated in wear track. However, the main mechanism of wear for Cr/sub 2/O/sub 3/ coating layer was brittle fracture under 150 N.

• Tribology and Lubricants
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• v.9 no.2
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• pp.36-48
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• 1993

This study is concerned with the changes (deterioration) of the mechanical properties of used oil in the gasoline engine. The analysed properties of used oil were friction, antiwear, wear debris, load-carrying ability and the formation of surface film. From this study, it was found that the oil used in engine was deteriorated to increase the wear and fricion and decrease the load-carrying ability as the running distance of oil was increased. Also the main cause of deterioration was related to the formation of the protective film on the contact zone. When the film was composed with rich additives (sulfur), this could properly protect contact zone from the increase of wear and friction. But as oil was deteriorated, it could not form such a film and therefore the protective ability of sliding surface diminished.

• Tribology and Lubricants
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• v.11 no.5
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• pp.55-58
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• 1995

The effects of Ni contents in Cu base sintered friction material were studied. The contents of Ni were increased up to 9 wt% in the Cu-Sn matrix. The microstincture and tribological behavior of the friction material were examined. Pin on disk type of constant speed friction test rig were used to measure the friction and the wear rates. The results show that Ni addition increased the friction coefficients and decreased the wear rates of the materials. Relations between microhardness of the matrix and friction properties have been discussed. In addition optimum Ni content is recommended through the analysis of wear debris.

• Journal of Biomedical Engineering Research
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• v.22 no.6
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• pp.519-526
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• 2001

At present. about 0.3 million and more THRs (Total Hip Replacement) in a rear are being done worldwide. The increase in mechanical failure with the increase in THR, required more revisions. Revisions compensate mainly the wear of the artificial joint frictional surface and the loosening of the cup and stem. According to recent researches, loosening is mainly due to wear debris UHMWPE (Ultra High Molecular Weight Polyethylene) from frictional surfaces . To overcome the wear problems associated with artificial joint materials , new surface structures with regular Patterns were designed and fabricated The lubrication Properties were examined to evaluate the wear of the frictional surfaces. The surface structure manifested a Pattern of "dents" with a 0.2-1.0 mm of diameter and 0.6-2.0 mm of Pitch. From the friction test of the SUS316L vs UHMWPE using the frictional tester, we found that the lubrication Performance was improved due to of drastically reduced amount of abrasion. There were optimum sizes for the diameter and the pitch of the Pattern. The results demonstrated that the lubrication properties could be improved by Patterning of the frictional surfaces. The surface Patterning was effective in preventing wear of the frictional surfaces, and the life of an artificial joint could be extended with such Patterning.