• Korean Journal of Materials Research
• /
• v.15 no.12
• /
• pp.824-828
• /
• 2005

In this study the effect of the content of $TiB_2$ on wear properties was investigated. $Cu-TiB_2$ composites have been fabricated by hot extrusion. Sliding wear tests were peformed by a pin-on-disk type wear test machine under dry condition and loads varied with from 20N to 80N at sliding speed 3.5Hz. The test results showed that the wear losses and the friction coefficients decreased with increasing $Cu-TiB_2$ volume fraction and increasing the size of $Cu-TiB_2$ particle. Wear property of $10{\mu}m,\;5 vol\%\; TiB_2$ specimen was excellent all of the wear specimens. It is thought that the increase of plastic flow resistivity due to uniform distribution of $10{\mu}m,\;5 vol\%\; TiB_2$ wear specimen would improve wear property. The worn surface and wear debris were examined by optical microscope and scanning electron microscope.

• Proceedings of the KWS Conference
• /
• 2003.05a
• /
• pp.114-116
• /
• 2003

The multi function sprayed coating is used for direct-heating, wear resistance and high bonding strength. The merits of surface direct-heating coatings are short warming time, low power consumption and better wear resistance that can be used in many organization parts. In this study, the surface direct-heating and wear resistance can be improved by spraying the proper materials on the surface $Al_2$O$_3$40%TiO$_2$ powder and Ni-20%Cr powder that had the properties of conduction and high wear resistivity are used in order to improve wear resistance, electrical properties and bonding strength.

• Journal of the Korean Applied Science and Technology
• /
• v.31 no.4
• /
• pp.679-687
• /
• 2014

In this study, a new paint which is able to resist the cavitation erosion is tried to be developed by using urethane added with nano particles such as multi-wall and single-wall carbon nano tube and spherical and fiber type graphite. The new paint synthesized was characterized with physical properties and resistivity to cavitation erosion($t_{50}$). Among nano particles, fiber type graphite($t_{50}$ 292min) showed high hardness and wear resistance compared with spherical type($t_{50}$ 182min). For carbon nano tube, single-wall type($t_{50}$ 286min) was higher than multi-wall type in wear resistance. Fiber-type graphite was the best nano-particle for paint with resistivity to cavitation erosion. In the application test of paint, the manually painted sample showed surface with smooth but the surface of sample prepared with spray was not smooth. During spray, dust was fixed on the surface.

• Journal of Power System Engineering
• /
• v.6 no.1
• /
• pp.74-81
• /
• 2002

The characteristics of corrosion resistance for the surface of ductile cast iron(GCD40) by plasma nitriding process have been studied in terms of electrochemical polarization behaviors including corrosion potential($E_{corr}$), anodic polarization trends, polarization resistance($R_p$), and also have been studied microstructures, hardness and specific wear of nitrided layer Nitrided layer showed an enhanced hardness values in all the plasma nitriding condition investigated. In the result of wear test, specific wear of nitrided specimens were much decreased than that of non-treated specimens. In the results of XRD, ${\gamma}'phase\;and\;{\varepsilon}$ phase were detected in nitrided surface. And it was found that ${\varepsilon}$ phase was decreased and ${\gamma}'phase$ was increased respectively, as the nitriding time became longer. In the test of corrosion resistance, natural potentials in all the nitrided specimens were towards noble directions than in the case of non-treated specimens. The measurement of electrode potentials revealed that corrosion resistivity of plasma nitrided specimens were higher than in the case of the non-treated specimens.

• Journal of the Korean Society for Precision Engineering
• /
• v.23 no.3 s.180
• /
• pp.69-75
• /
• 2006

In this paper, micro electrical discharge milling using deionized water as dielectric fluid was investigated. In EDM, dielectric fluid is an important factor which affects machining characteristics. When deionized water was used as dielectric fluid, machining characteristics were investigated according to voltage, capacitance, and resistivity of deionized water. Machining gap increased with increasing voltage and capacitance. As the resistivity of deionized water decreased, the machining gap increased. The wear of a tool electrode and machining time can be reduced by using deionized water instead of EDM oil. Surface roughness was also improved when deionized water was used.

• Journal of the Korean Society for Precision Engineering
• /
• v.19 no.3
• /
• pp.114-122
• /
• 2002

Electric conductivities, mechanical properties and friction properties were investigated far graphite-nylon composites impregnated with oil. Specific resistivity of composites containing oil from 2% to 6% were in the range of $10^7 ~10^6 \ohm$ cm, which were applicable for anti-static purpose of composites improved by the impregnation of graphite with 2%. Improvement in the impact strength and friction properties of graphite/nylon composites was achieved by the impregnation of oil. The coefficient of friction of the composites containing graphite from 2% to 4% and oil with 2 - 4% showed much loller than that of virgin nylon. Also the abrasive wear of the oil impregnated graphite composites were decreased about 1/3 - 1/10.

• Journal of the Korean institute of surface engineering
• /
• v.15 no.4
• /
• pp.208-217
• /
• 1982

To study the effect of TiC coating on weight change, microhardness, wear and heat - resistance of TiC layer, chemical vapour deposition on the various substrates has been carried out with the gaseous mixture of TiCl4, toluene, and H2 in the temperature range of 900 - 1000$^{\circ}C$. The results obtained are as follows ; (1) There is a limited value of carrier and reductant H2 gas flow rate, above which deteriorate effect on the TiC depoition arises (2) Increased thickness of TiC layer was resulted with increasing temperature and time. Better deposition was obtained with stainless steels and the best results were introduced by cobalt coating of substrates. (3) Wear resistance of the TiC coated specimen improved markedly. Heat resistivity of the coated steel showed excellent result, whereas the coated stainless Steels were infer-ior to the substrate.

• 한국신재생에너지학회:학술대회논문집
• /
• 2005.06a
• /
• pp.546-549
• /
• 2005

Micro EDM milling using deionized water as dielectric fluid was investigated. After machining micro grooves using deionized water with different voltage. capacitance. and resistivity of deionized water, machining characteristics were investigated. The wear of a tool electrode and the machining time can be reduced by using deionized water instead of kerosene. Micro hemispheres were machined in deionized water and kerosene and their machining characteristics were compared.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.12 no.4
• /
• pp.123-130
• /
• 2013

Zirconia is well known in industrial applications for its mechanical characteristics. DLC (diamond-like carbon) have high elastic modulus, high electric resistivity, high dielectric constant, high wear resistance, low friction coefficient, bio compatibility, chemically inert and thermally stable. Because of all these physical and chemical properties these types of coatings have become key procedure for thin coating. Friction coefficient of DLC films is already evaluated and the current work is a further advancement by calculating the fracture toughness and wear resistance of these coatings. In the present study DLC thin film coatings are developed on $ZrO_2$ alloy surface using Plasma Enhanced Chemical Vapor Deposition (PECVD) method. Vicker hardness test is employed and it was concluded that, DLC coatings increase the Vickers hardness of ceramics.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.8 no.1
• /
• pp.111-116
• /
• 1998

Silicon nitride is hard and tough ceramic material. Hereby, mechanical machinability is very poor. It has also high electrical resistance. Silicon nitride of extremely high electrical resistivity becomes conductive ceramic composite by adding 30 wt% TiN. Ceramics with high electrical conductivity can be electrical discharge machined. Using by the Electrical Discharge Machining (EDM) technique. $Si_3N_4-TiN$ ceramic composite with high electrical conductivity is utilized to make metal working tool. These tool materials have severe wear problem as well as oxidation. Post HIP processing after sintering $Si_3N_4-TiN$ ceramic composites was performed. The tribological property of $Si_3N_4-TiN$ composite as a function of content of TiN was investigated in air, at room temperature. The hardness, fracture toughness, and flexural strength were compared with the wear volume. SEM observation of wear tracks can make an explanation of wear mode of $Si_3N_4-TiN$ composite.