• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1997.10a
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• pp.93-99
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• 1997

High Temperature wear behavior of plasma sprayed ZrO$_2$ and MoS$_2$, $Fe_2O_3$ coatings were investigated for high temperature wear resistance applications. The MoS$_2$, $Fe_2O_3$ added powders containing 2.5, 5.0, 7.5, 10.0 mol% of $MoS_2$, $Fe_2O_3$ for plasma spray were made by spray drying method. Wear test were performed at temperature ranges from room temperature to 600$\circ$C. The microstructural change of coatings and the worn. surface were examined by SEM and XRD. In ZrO$_2$ coating, the coefficient of friction and wear amount of room temperature to 400$\circ$C was increased with temperature and decreased with temperature over 400$\circ$C. The coefficient of friction and wear amount of MoS$_2$ added coatings were increased with temperature, but those of $Fe_2O_3$ added coatings had lower coefficient of friction and higher wear resistance than ZrO$_2$ coating.

• Journal of the Korean Society for Heat Treatment
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• v.13 no.6
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• pp.405-411
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• 2000

The effects of added elements, such as Co or Nb, on wear properties of high speed steel by powder metaliurgy(PM-HSS) had been eluminated in auther's previous paper. In addition, it is generally known that the wear properties of materials have been influenced by heat-treating conditions as well. Therefore, a study has been done to clarify the effects of heat-treating conditions on wear properties of PM-HSS. The wear tests have been performed under the same conditions as the previous paper using heat-treated PM-HSS(5%Co-1%Nb) with different quenching and tempering temperatures. The result of this paper shows that wear resistance of PM-HSS is improved with relatively high quenching temperature. However, tempering temperature is not sensitive to the wear resistance in the range of high quenching temperature. It may be deduced by the fact that the shear strength of matrix by strengthening mechanisms due to not only the quenching aging but also dispersion-hardening is improved.

• Journal of the Korean Society for Heat Treatment
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• v.29 no.6
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• pp.284-291
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• 2016

High temperature alloy steel such as Ni-Cr-Mo-V material has excellent properties of high strength and high heating resistance. It has been used for several military weapon components such as gun barrel of a warship, turbine rotor and turbine disk for nuclear power plant. Being curious about this material required excellent wear resistance and durability in extreme environmental conditions. A dry wear test at the ambient air and Ar gas conditions in the room temperature were performed in this study. What's more a lubricant wear test at different temperature was conducted. In addition that DLC was coated on Ni-Cr-Mo-V alloy steel substrate with a thickness of $3{\mu}m$, a property of it was compare with lubricant conditions. All the coefficient of friction and wear volume, comparing with DLC coated specimens. The test parameters were selected as follows: 10 N for normal load; 80 rpm for sliding wear speed; and 300 m for the sliding wear distance.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.22 no.6
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• pp.895-900
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• 2013

Several plasma spray and metallurgical surface coatings such as $Al_2O_3$, $Cr_2O_3$, WC-Ni, and chromizing coating have been examined for their application in environments with high temperature, wear, and corrosion. The chromizing coating is different from others coatings in the manufacturing process the surface. These coatings' characteristics were tested experimentally, and the results were compared. WC-Ni shows good performance against thermal barrier, wear, and corrosion and is one of the best candidates for the environment considered herein. These coatings were studied for their application in the steel manufacturing industry. The most commonly required functions in this industry are thermal and wear resistance.

• Composites Research
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• v.12 no.5
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• pp.12-22
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• 1999

Aluminum based metal matrix composites(MMCs) are well known for their high specific strength, stiffness and hardness. They are gaining further importance because of their high wear resistance. In this study wear behavior of $Al/Al_2O_3/C$ hybrid MMCs fabricated by squeeze infiltration method was characterized by the abrasive wear test under various sliding speeds at room and high temperature. Wear resistance of MMCs was improved due to the presence of reinforcements at high sliding speed. Especially wear resistance of carbon hybrid MMCs was superior to other materials because of its solid lubrication of carbon. The friction coefficient of MMCs was not affected by the sliding speed.

• Proceedings of the Korean Vacuum Society Conference
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• 1995.06a
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• pp.151-151
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• 1995

Nitrogen implantation process has been applied for improvement of wear resistance of Z Zircaloy-4 fuel cladding materials. Nitrogen was implanted at 120 ke V to a total do range of 1xHP ions/cm2 to 8xlO17 ions/cm2 at various temperatures of 298"C to 676"C. The m microstructure changes by nitrogen implantation were analyzed by using TEM, XRD 뻐d A AES, cmd then wear behavior was evaluated by ball-on-disc wear testings at various loads a and sliding velocity under unlubricated condition. Nitrogen implantation produced ZrNx nitride above 4.37x1017 ions!cm2 as well as heavy d dislocations, which enhanced microhardness of the implanted surface of up to 900 Hk from 2 200 Hk of unimplanted substrate. Hardness was also found to be increased with increasing i implantation temperature and enhanced up to OOOHk at 620 "C. the wear resistance was g greatly improved with increasing total ion do않 as well as implantation temperature. The effective enhancement of wear resistance at high dose and tem야ratures is believed d due to significant hardening associated with high degree of precipitation of Zr nitrides and g generation of prismatic dislocation I$\infty$ps.infty$ps.

• Journal of the Korean Society for Heat Treatment
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• v.16 no.3
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• pp.134-140
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• 2003

Effects of cryogenic treatment and tempering temperature on the amount of retained austenite, hardness and wear properties has been investigated using alloy tool steel, STD 11. Cryogenic treatments were performed at the temperatures of $-100^{\circ}C$, $-150^{\circ}C$ and $-196^{\circ}C$, and tempering were performed at $200^{\circ}C$ and $530^{\circ}C$. It was shown that lower hardness value was obtained on high temperature ($530^{\circ}C$) tempering even after cryogenic treatment. And retained austenite was not entirely transformed to martensite after cryogenic treatment even at $-196^{\circ}C$, which was not consistent with the belief that $-80^{\circ}C$ was sufficient to entirely transform any austenite retained in the quenched microstructure. Austenite retained in cryogenic treated condition was completely transformed to martensite only after tempering at $530^{\circ}C$. As far as wear test conditions in this investigation, it was found that cryogenic treatments improved the sliding wear resistance, but improvement of wear resistance was not directly related with retained austenite contents. And it was found that predominent wear mechanisms of STD 11 steel were oxidation wear and adhesive wear In sliding wear conditions.

• Journal of the Korean institute of surface engineering
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• v.32 no.2
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• pp.144-156
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• 1999

Thermal Barrier Coating with Functional Gradient Materials (FGM-TBC) can play an important role to protect the parts from harmful environments in high temperatures such as oxidation, corrosion, and wear and to improve the efficiency of aircraft engine by lowering the surface temperature on turbine blade. FGM-TBC can increase the life spans of product and improve the operating properties. Therfore, in this study the evaluations of mechanical and thermal properties of FGM-TBC such as fatigue, oxidation and wear-resistance at high temperatures have been conducted. The samples of both the TBC with 2, 3, 5 layers (YSZ/NiCrAlY) to be produced by Air Plasma Spray method (APS) and the bulk TBC with 6 layers to be produced by Plasma Assisted Sintering method (PAS) were used. Furthermore, residual stress, bond strength, and thermal conductivity were evaluated. The average thickness of the APS was 500$\mu\textrm{m}$ to 600$\mu\textrm{m}$ and the average thickness of the PAS was 3mm. The hardness number of the top layer of APS was 750 Hv to 810Hv and that of PAS was 950 Hv to 1440Hv. The $ZrO_2$ coating layer of APS was composed of tetragonal structure after spraying as the result of XRD analysis. As shown in the results of the high temperature wear test, the 3 layer coating of APS had the best wear resistance at $800^{\circ}C$ and the 5 layer coating of APS had the best wear resistance at $600^{\circ}C$. But, these coatings had the tendency of the low-temperature softening at $300^{\circ}C$. The main mechanism of wear was the adhesive wear and the friction coefficient of coatings was increased as increasing the test temperatures. A s results of thermal conductivity test, the ${\Delta}T$ of the APS coating was increased as number of layer and the range of thermal conductivity of the PAS was $800^{\circ}C$ to $1000^{\circ}C$.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2000.04a
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• pp.75-78
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• 2000

There are several effective factors to influence die life in the warm forging process. For instance process design die design and die materials etc This study presented heat treatment method which could improve toughness and wear resistance simultaneously in high temperature to apply high speed tool steels like SKH51 to die material for warm forging process. To verify the feasibility of application of heat treatment method mentioned above wear test was performed under the condition of constant time in 40$0^{\circ}C$ Wear coefficient was examined to search a relation between wear amount and time for each material and heat treatment method in 30, 60, and 130 minutes. To quantify the toughness-behavior between room and high temperature impact test was performed and heat fatigue test also fulfilled to compare with the resistance of heat check in room, 200, 400, and $600^{\circ}C$ temperature. On the basis of experimental results mentioned above high speed tool steel was applied to verify appropriateness of newly proposed heat treatment method for die of rotor pole used in automobile alternator. As a result die life of high speed tool steel applied newly proposed heat treatment is longer than that of STD61.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.20 no.2
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• pp.162-168
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• 2011

In this research, nitrogen plasma source ion implantation(PSII) of non-coated tungsten carbide endmill tools was conducted with low heat treatment for increasing wear resistance. After the low heat treatment of PSIIed tools to give a homogeneity of wear resistance, the surface modification of tools was analyzed by hardness test, surface roughness and cutting forces. As for the resultant cutting forces, low heat treatment in temperature of $400^{\circ}C$ and $500^{\circ}C$ is stable because of low cutting resistance. The 20-minutes heat treated tool at spindle speed 25000rpm has superiority of surface roughness, Ra of $0.420{\mu}m$ and was found to have good wear resistance. The higher hardness value was obtained by increasing temperature from $300^{\circ}C$ to $600^{\circ}C$ for PSIIed tools with low heat treatment. As the PSIIed tools under 10minutes at temperature of $600^{\circ}C$ have the highest hardness as Hv of 2349.8, It was analyzed that temperature processing give much influences on hardness.