• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1996.10a
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• pp.157-165
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• 1996

Characteristics of microstructure, hardness and wear of two AI-20Si-5Fe-2Ni materials produced by powder metallurgy and spray forming respectively were studied at temperatures up to 560$^{\circ}C$. Above 300$^{\circ}C$, the microstructure of powder processed alloy became inhomogenous, whereas the spray formed alloy showed homogeneous microstructures. Hardness of both alloys was increased between 300$^{\circ}C$~490$^{\circ}C$ in both alloy. It was interpreted that increase in hardness was mainly related to the formation of stable and fine intermetallic phase from metastable one. It was showed that hoogenity of microstructure in the rapidliy soldified affected directly wear property.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.16-21
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• 2002

The high speed machining center(HMC) has been widely applied to manufacture a die and trial product in many machine industry. Because the evaluation fer the HMC is not sufficiently performed and the efficient cutting conditions aren't selected, a great loss has been caused in the cost aspect. In this study, the need of preliminary running time and unstable spindle speed is presented from the analysis of acceleration in idling. The Machinability fur the TiAlN coated flat end mill and STD11( $H_{R}$C60) is evaluated from the trends of tool wear and cutting force according to cutting conditions and slenderness ratio and a low response of tool dynamometer in high speed is proved. The resonance spindle speed is identified through the tool wear and natural frequency test.t.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.1313-1314
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• 2006

For improvement of wear resistance property of atmospheric thermal plasma sprayed molybdenum (Mo) coating, diamond deposition on the atmospheric plasma sprayed molybdenum coating by the combustion flame chemical vapor deposition (CFCVD) has been operated. In this study, to diminish the thermal damage of the substrate during operation, a thermal insulator was equipped between substrate and water-cooled substrate holder. Consequently, diamond particles could be created on the Mo coating without fracture and peeling off. From these results, it was found that this process had a high potential in order to improve wear resistance of thermal sprayed coating.

• Tribology and Lubricants
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• v.4 no.2
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• pp.44-51
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• 1988

Titanium carbide(TiC), Titanium nitride(TiN), and Titanium carbonnitride(Ti(C,N)) films were deposited on $Si_3N_4$-TiC composite cutting tools by chemical vapor deposition(CVD) using $TiCl_4-CH_4-H_2$, $TiCl_4-N_2-H_2$, and $TiCl_4-CH_4-N_2-H_2$ gas mixtures, respectively. The experimental results indicate that TiC coatings compared with TiN coatings on $Si_3N_4$ -TiC ceramic have an improved microstructural property, good thermal shock resistance, and good interfacial bonding. However TiN coatings compared with TiC coatings have a low friction coefficient with steel and good chemical stability. It is found by cutting test that coated insert compared with $Si_3N_4$-TiC ceramic have a superior flank and crater wear resistance. And multilayer coating compared with monolayer coating shows a improved wear resistance.

• Korean Journal of Materials Research
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• v.20 no.4
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• pp.194-198
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• 2010

Cubic boron nitride (c-BN) is a promising material for use in many potential applications because of its outstanding physical properties such as high thermal stability, high abrasive wear resistance, and super hardness. Even though 316L austenitic stainless steel (STS) has poor wear resistance causing it to be toxic in the body due to wear and material chips, 316L STS has been used for implant biomaterials in orthopedics due to its good corrosion resistance and mechanical properties. Therefore, in the present study, c-BN films with a $B_4C$ layer were applied to a 316L STS specimen in order to improve its wear resistance. The deposition of the c-BN films was performed using an r.f. (13.56 MHz) magnetron sputtering system with a $B_4C$ target. The coating layers were characterized using XPS and SEM, and the mechanical properties were investigated using a nanoindenter. The friction coefficient of the c-BN coated 316L STS steel was obtained using a pin-on-disk according to the ASTM G163-99. The thickness of the obtained c-BN and $B_4C$ were about 220 nm and 630 nm, respectively. The high resolution XPS spectra analysis of B1s and N1s revealed that the c-BN film was mainly composed of $sp^3$ BN bonds. The hardness and elastic modulus of the c-BN measured by the nanoindenter were 46.8 GPa and 345.7 GPa, respectively. The friction coefficient of the c-BN coated 316L STS was decreased from 3.5 to 1.6. The wear property of the c-BN coated 316L STS was enhanced by a factor of two.

• Korean Journal of Materials Research
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• v.13 no.12
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• pp.839-845
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• 2003

The abrasion and impact wear resistance were investigated on the hardfacing weld dispersed with the recycled hard metal(HM). The HM was composed of the tungsten carbide(WC) reinforced metal matrix composite. The cored wire filled with the 25-35wt.% HM and 2-8wt.% of the alloying element, Fe-75Mn- 7C(FeMnC), was used for the gas metal arc(GMA) welding. By using the cored wire of the 25wt.% HM and FeMnC addition, the weld showed mostly constant wear loss for the abrasion as a function of the FeMnC content. This was due to the insufficient amount of the tungsten carbide formed during the GMA welding. The FeMnC addition to the 35wt.% HM did not improve the abrasion wear property since the amount of the tungsten carbide formed was decreased with respect to the FeMnC amount. The 6wt.% FeMnC addition to the 35wt.% HM exhibited the better impact wear resistance than the hardfacing weld by 40wt.% HM.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2016.11a
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• pp.117-117
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• 2016

Total ankle replacement (TAR) is a visible option in the surgical treatment of degenerative or inflammatory diseases of ankle joint. it is attributed to the current TAR which has improvements in surgical technique, uncemented implant fixation and minimally constrained articulation. In the clinical result, they can show promised surgical result when compared to earlier attempts in TAR. However, TAR is still not as successful as total knee replacement (TKR) or total hip replacement (THR), it needs to be note that there are limitations in concerning of long term performance of TAR, the high failure rate still associated with wear of the PE (polyethylene) component that has related with their material property and surface roughness. The aim of this study was to introduce the tribology characteristics of total ankle joint prosthesis with one of TDR model which was fabricated to try multi-axis wear test as a region of motion in ankle joint. The wear specimen of TDR was prepared with Ti-6Al-4V alloy and UHMWPE (ultra-high molecular weight polyethylene) for tibia-talus and bearing component, respectively. A wear test was carried out using a Force 5 (AMTI, Massachusetts, US) wear simulator which can be allowed to move in three axis to flexion-extension ($+3^{\circ}{\sim}-6^{\circ}$), internal-external axial rotation (${\pm}5^{\circ}$), as well as sinusoidal compressive load (1.6 kN, R=10). All tests were performed following standard ISO 14243, wear rate was calculated with weight loss of UHMWPE bearing while the specimen has tested at certain cycles. As based on the preliminary results, wear rate of UHMWPE bearing was $7.9{\times}10^{-6}mg/cycles$ ($R^2=0.86$), calculated loss weight until $10^7cycles$ was 79 mg, respectively.

• Journal of Powder Materials
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• v.26 no.5
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• pp.421-431
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• 2019

In this study, the formation, microstructure, and wear properties of Colmonoy 88 (Ni-17W-15Cr-3B-4Si wt.%) + Stellite 1 (Co-32Cr-17W wt.%) coating layers fabricated by high-velocity oxygen fuel (HVOF) spraying are investigated. Colmonoy 88 and Stellite 1 powders were mixed at a ratio of 1:0 and 5:5 vol.%. HVOF sprayed self-fluxing composite coating layers were fabricated using the mixed powder feedstocks. The microstructures and wear properties of the composite coating layers are controlled via a high-frequency heat treatment. The two coating layers are composed of ${\gamma}-Ni$, $Ni_3B$, $W_2B$, and $Cr_{23}C_6$ phases. Co peaks are detected after the addition of Stellite 1 powder. Moreover, the WCrB2 hard phase is detected in all coating layers after the high-frequency heat treatment. Porosities were changed from 0.44% (Colmonoy 88) to 3.89% (Colmonoy 88 + ST#1) as the content of Stellite 1 powder increased. And porosity is denoted as 0.3% or less by inducing high-frequency heat treatment. The wear results confirm that the wear property significantly improves after the high-frequency heat treatment, because of the presence of well-controlled defects in the coating layers. The wear surfaces of the coated layers are observed and a wear mechanism for the Ni-based self-fluxing composite coating layers is proposed.

• Fashion & Textile Research Journal
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• v.14 no.2
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• pp.277-285
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• 2012

This research studied how to develop tight upper sportswear from 3D scan data considering fabric stretch property. Subjects were five Korean men of average figure in their 20's. Scanning was done for ten postures via vitus smart/pro(Techmath LTD). Analyzing from 3D scan data, more than 70% of the upper body surface showed surface change rate under 20%. It was shoulder and under arm side part that showed most noticeable body surface change when moving. A parametric model with convex surface was generated and flattened onto the plane, resulting 2D pattern. The error rate occurring in the process of 3D to 2D conversion was 0.2% for outline and 0.13% for area, respectively. Thirteen kinds of stretchable fabrics in the market were collected for this study. Stretch property was in the range of 16.0~58.2% for wale direction; 23.1~78.4% for course. Based on wear trial test, four fabrics were chosen for making the 1st experimental garment and finally one fabric was chosen for the 2nd one, which was developed applying 4 kinds of crosswise reduction rate on 2D pattern: 0, 5, 10, and 15%. Through wear trial test and garment pressure measurement, experimental garment applied with 10% pattern reduction rate was evaluated as most comfortable and considerable.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.8
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• pp.1178-1184
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• 2008

In this study, techniques of ion implantation were used in order to improve the characteristics of metal materials such as the oxidation and wear resistant. In particular it is necessary to develope their oxidation and wear resistant that could be used in severe environmental conditions. There are mainly two elementary technologies including ion implantation and/or thin film coating. Ion implantation method was performed for surface modification. As a result, it was found that some ion implantations methods such as Nb, high-temperature Nb ion implantation and Nb+C combined implantation are somewhat effective for improving the oxidation resistance of TiAl alloy. Furthermore, the fluorine PBII treatment is more effective for improving the oxidation resistance of the TiAl alloy with three-dimensional shapes. The implantation of boron ion into thin film of TiN was also effective for improving the properties of materials like high temperature wear resistance. TiCrN film was applied to the actual seal ring for steam turbines, and it was observed that its sliding property showed a successfully good performance.