• Journal of the Korean Ceramic Society
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• v.35 no.7
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• pp.721-725
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• 1998

In this study solid-phase sintered silicon caribide samples composed of SiC powder having boron and car-bon black as additives were prepared by pressureless sintering at $1950^{\circ}C$. The bending strength the frac-ture toughness and the specific werar rate of the samples were examined and the micro structures of the broken and the worn surface were observed by SEM to understand the relationship between the tri-bological charcteristics and the micro structure. Additionally the relationship between the micro struc-tures and the tribological characteristics of the samples for the frictional opponents SiC and $Al_{2}O_{3}$ pins were investigated Conclusions are as follows ; 1. The specific were rate of the samples for the SiC pin was larger than that for the $Al_{2}O_{3}$ pin. HOwever the specific wear rate for the $Al_{2}O_{3}$ pin was increased about 6,45 times as that for the SiC pin under the load increasing. 2. The specific wear rate of the SiC pin was larger than that of the $Al_{2}O_{3}$ pin. owever the specific wear rate of the $Al_{2}O_{3}$ pin was increased about 4 times as that of the SiC pin under the load increasing 3. The micro stucture of the worn surface showed a flat face without cracks in the case that the frictional opponents has the low friction coefficient but in the case of without cracks in the case that the frictional opponents has the low friction coefficient but in the case of the high friction coefficient the micro structure of the worn surface showed an uneven face having spread-ed cracks. 4. The tribological characteristics of thesolid-phase sintered SiC samples was similar to that of li-quid-phase sintered ones when the pin having the high friction coefficient was used.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.4 s.175
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• pp.900-906
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• 2000

Ceramic, PCD and CBN tools are available for the difficult-to-cut-materials such as hardened carbon tool steel, stainless steel, Inconel 718 and etc. Ceramic tools are likely to be chipped and abruptly broken before the appearance of normal wear in turning. Ceramic tools are suitable for continuous in turning, not for intermittent in milling. In this study, TiN/TiCN multi-layer coated ceramic tools were found to restrain the chipping, breaking and early fracture and to increase the critical cutting speed owing to TiN/TiCN multi-layer coating in Arc Ion Plating of PVD method.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2000.10a
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• pp.386-391
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• 2000

It is known that Si$_3$N$_4$ceramic insert has less hardness than A1$_2$O$_3$ceramic insert. But Si$_3$N$_4$ceramic insert has not only high toughness and strength but also low thermal expansion coefficient, which makes it has longer tool life under thermal stress condition. In this study, commercial Si$_3$N$_4$ ceramic insert and home-made SiC-Si$_3$N$_4$ceramic insert which has different sintering time and chemical composition is tested under various cutting conditions. The experimental result is compared in terms of tool life and cutting force. Generally, As the cutting speed and the feed rate increased, the cutting force and the flank wear increased too. The performance of SiC-Si$_3$N$_4$ceramic insert shows the possibility to be a new ceramic tool.

• Korean Journal of Metals and Materials
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• v.48 no.11
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• pp.1003-1008
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• 2010

In this study, the effect of the reinforcement on the wear behaviour and mechanical properties of hypereutectic Al-Si alloys was investigated. The Gas atomized hypereutectic Al-20Si alloy powders were mixed with 1, 3, and 5 wt.% AlN and TiC ceramic particles and consolidated by hotpress. The Al-20Si powder has both finely dispersed primary Si phases and eutectic structures. The Al-20Si-AlN, TiC composites showed that the reinforcements were distributed along the boundary of the Al-20Si alloy. The UTS increased with increasing the AlN, TiC contents. At a lower load, with an increasing weight fraction of reinforcements, the wear rate decreased in both composites and the wear mechanism was adhesive wear. At a higher load, the shape of the debris changes the mechanism of the AlN composites to abrasive-adhesion wear and this resulted in an increase of the wear rate.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.1057-1060
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• 2004

In this study, the wear characteristics of five different dental composite resins cured by conventional halogen light and LED light sources were investigated. Five different dental composite resins of Surefil, Z100, Dyract AP, Fuji II LC and Compoglass were worn against a zirconia ceramic ball using a pin-on-disk type wear tester with 15 N contact force in a reciprocal sliding motion with sliding distance of 10 mm/cycle at 1Hz under the room temperature dry condition. The wear variations of dental composite resins were linearly increased as the number of cycles increased. It was observed that the wear resistances of these specimens were in the order of Dyract AP ＆gt; Surefil ＆gt; Compoglass ＆gt; Z100 ＆gt; Fuji II LC. On the morphological observations by SEM, the large crack formation on the sliding track of Fuji II LC specimen was the greatest among all resin composites. Dyract AP showed the least wear with few surface damage. There is no significant difference in wear performance between conventional halogen light curing and light emitting diodes curing sources. It indicates that a light emitting diodes (LED) source can replace a halogen light source as a curing unit for composite resin restorations.

• Journal of the Korean Ceramic Society
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• v.39 no.6
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• pp.558-565
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• 2002

Coal fly ash, produced from a power plant in Korea was used for the production of glass-ceramics and the physical properties of glass-ceramics were evaluated. CaO and TiO$_2$ were added into the fly ash during the melting process to reduce the viscosity of molten glass and to induce internal crystallization of glass, respectively. Glass-ceramic was produced through a single stage heat treatment (at 950∼1050$\^{C}$ for 37∼240 min) after preparing glass (iota fly ash powder. As a result, a new tiny rod type crystals (a=7.4480, b=10.7381, c=4.3940 A, $\alpha$=94.9, $\beta$=98.6, γ=108.5°) was found in the glass-ceramics, which showed attractive mechanical properties, high hardness (7.1∼7.6 GPa) and wear resistance (by erosion test). Thus a glass-ceramic produced from thermal power plant fly ash and cell as a source for CaO exhibits a suitable treatment for the recycling and exploitation of waste materials and would be acceptable for a new application far building materials.

• Carbon letters
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• v.26
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• pp.51-60
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• 2018

An electroless deposition method was used to modify the surface properties of rice husk ceramic particles (RHC) by depositing nano-nickel on the surface of the RHC (Ni-RHC). The dry tribological performances of aluminum matrix composite adobes containing different contents of RHC and Ni-RHC particles have been investigated using a micro-tribometer. Results showed that the Ni-RHC particles substantially improved both the friction and wear properties of the Ni-RHC/aluminum matrix adobes. The optimal concentration was determined to be 15 wt% for both the RHC and Ni-RHC particles. The improvements in the tribological properties of aluminum adobes including the Ni-RHC were ascribed to friction-induced peeling off of Ni coating and formation of protection layer on the wear zone, both of which led to low friction and wear volume.

• Journal of the Korean Ceramic Society
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• v.31 no.8
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• pp.874-878
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• 1994

To increase the anti-oxidation and anti-wear properties of graphite for the propellant-burning environment, SiC, Pt and Al2O3 multi-layer coatings were conducted succesisvely and the optimum condition was researched. The SiC layer was produced by pack cementation and SiC layer in thickness of 30 ${\mu}{\textrm}{m}$ coating was produced after coating for 6 hours. Pt layer was coated by sputtering, and the Al2O3 layer was coated by reactive sputtering. the thickness of Pt layer and Al2O3 layer was less than one-tenth of that of SiC layer. The pack coated specimens and multi-layer coated specimens were made using above conditions and test-fired. The test result showed that the wear rate of SiC layer is approximately 1/10 compared to that of uncoated graphite.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.9 no.1
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• pp.96-101
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• 2000

Ceramic, PCD and CBN tools are available for the difficult-to-cut-materials such as hardened carbon tool steel, stainless steel, Inconel 718 and etc.. Ceramic toolsare likely to be chipped and abruptly broken before the appearance of normal wear in turning. Ther2efore ceramic tools are suitable for continuous cut in turning not for intermittent in milling. In this study, TiN/TiCN multi-layer coated ceramic tools were found to restrain the chipping, breaking and early fracture and to increase the critical cutting speed owing to TiN/TiCN multi-layer coating in Arc Ion Plating of PVD method.

• Tribology and Lubricants
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• v.27 no.2
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• pp.95-100
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• 2011

The brake disc materials for railway vehicle have been mainly used cast-iron. The brake disc and pad should be light, resist to a thermal crack and absorb enough friction energy. In order to satisfy this requirement, aluminum alloy brake disc for railway vehicle has been newly developed. The aluminum itself has not been considered the friction material for railway vehicle. However, in the case of aluminum composite with dispersed ceramic particles, friction characteristics, resistance to wear and heat are much improved. In the present study, aluminum composite brake disc of 20% ceramic particle and three kinds of organic pads have been tested in dynamometer. The results show that Al MMC brake disc and pad have good friction coefficient and wear rate, and thermal cracks in brake disc have not been initiated. Also, the Al MMC brake disc can be applied to railway vehicle of 150 km/h.