• Journal of Powder Materials
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• v.5 no.4
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• pp.303-311
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• 1998

Hard materials such as hardmetal, coated hardmetal, cermet, ceramics and diamond or c-BN sintered compact are a kind of grain-dispersed alloy with high volume of hard particles. These are used for cutting tools, wear-resistant tools, rock bits, high pressure apparatus, etc. The annual production in Japan is about 1.7 billion dollars (200 billion yen). This is greatly owed to the development in science and technology which has been accomplished by applying new concepts such as fine or uniform grain microstructure, orientation of crystal grains, functionally graded material, artificial lattice and coherent bonding in recent years. In this review, the development in recent years in Japan is briefly summarized.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.802-806
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• 2001

Chrome-molybden steel or chrome steel for machine structural use been shown to excellent hardenability adding boron of a small amount at low carbon steel. In the country boron steel has been used widely high strength volt and wear resistant components of construction equipment. SEM results showed classical fatigue fractures, consistent with surface crack initiation. The speciments were cycled using under load controlled rotary bending fatigue tests. In this study, the fatigue crack initiation as well as the fatigue crack growth behavior and the fracture mechanism were investigated through observations of fracture surface boron steel(AISI 51B20).

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.05a
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• pp.783-791
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• 2000

Increasing demands in productivity are propelling the development of new manufacturing methods like hard machining, high speed cutting (HSC) or machining of difficult to machine materials. In these processes the toois are subjected to very severe mechanical, tribological and thermal loads. They fail prematurely by abrasion, cratering, edge breakage and cold welding. The performance of such tools will be enhanced by better and more wear resistant coatings. The development of these new coatings shows a clear trend towards complex multi-component and multi-layer configurations. TiAIN multilayer coating belongs to these coatings for the new cutting tool generation. This paper tries to explain the benefits of the new coatings. TiAIN multilayer coating offers the following advantages: reduction of manufacturing costs. boost productivity, and lower coolant procurement, conditioning and disposal costs.

• Journal of Advanced Marine Engineering and Technology
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• v.19 no.4
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• pp.51-60
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• 1995

Along with the rapid development of automobile industry in this country the necessity of high quality braking material is ever increased to maintain the comfortness as well as the safety the passengers. Asbestos-based friction materials are banned in the developed countries because of their cancer-inducing effect. This study focuses on the development of non-acbestos friction material with acceptable properties such as wear resistant high temperature endurant and low-noise enducing. We have all the intermediate test results indicating the contribution of each additives. These are qualitatively analyzed. Manufacturing processes such as opening of the kevlar and degasing at elevated temperature is equally important to attain proper level of friction quality.

• Journal of Powder Materials
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• v.1 no.1
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• pp.60-65
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• 1994

When a commercial prealloyed Fe-powder(Fe-5Cr-lMo-2Cu-0.5P-3C) is liquid phase sintered at 116$0^{\circ}C$, liquid precipitates with various shapes form within solid grains during the initial stage of sintering. The shape of a liquid precipitate changes pith the increment of their size from sphere(with radius<0.3$\mu\textrm{m}$), a transient polyhedron with more than 7 faces(1~2 $\mu\textrm{m}$), cuboid(3~5 $\mu\textrm{m}$), and finally to sphere(>5 $\mu\textrm{m}$). The shapes of liquid precipitates closely resemble the growth shapes predicted on the basis of solid-liquid interfacial energy and the coherency strain energy with anisotropic elastic constants in the diffusion zone around the precipitates.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1988.11a
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• pp.35-48
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• 1988

상대 접촉하고 있는 물체에 미끄럼 운동이 가해질 경우 마찰에 의해 발생되는 거의 모든 에너지는 열로써 나타나게 된다. 이러한 마찰열은 주로 adhered junctions의 파괴 및 표면돌기(surface asperities)들의 소성 변형에 의한 열역할적 비가역 반응의 결과로 발생된다. 접촉부위의 발생열은 양 접촉제의 접촉면에 전달되어 접촉표면 온도의 급격한 증가를 초래하며 그 결과로 여러가지 surface phenomena, 즉 마찰, 마모, 산화(oxidation), 부식 및 구조적 열화(structural degradation) 금속학적 상변화등에 큰 영향을 미치게 된다. 딸서 볼 및 로울링 엘레먼트 베어링, 기어, 캠과 태핏, 브레이크 등 기계요소의 설계를 위한 주인자로서 근래에 들어 접촉표면의 온도가 주목받고 있다. 표면에 존재하는 layer로서는 금속표면에 응착시킨 coating layers, contaminant films, physisorbed 또는 chemisorbed films, oxide layers 또는 마찰열에 의해 형성되는 경도가 아주 높은 내마모층(hard wear-resistant layers) 등이 고려될수 있다. 낮은 열전도성을 가진 oxide film이 접촉 표면이 온도를 증가시킨다는 것이 Jaeger에 의해 지적되었으며 Ling과 Lai는 moving heat sjource가 가해지는 layered surface의 표면온도분포를 구하면서 substrate와 thermal property가 다른 layer가 존재하게 되면 그 두께가 아주 얇더라도 (1 마이크론 정도) 표면온도는 크게 변화됨을 보였다.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.11
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• pp.174-178
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• 2001

Chrome-molybden steel or chrome steel for machine structures has been shown to excellent hardenability adding boron of a small amount at low carbon steel. These days, boron steel has been used high strength bolt and wear resistant components of construction equipment. SEM results showed classical fatigue fractures, consist with surface crack initiation. The specimens were tested repeatedly(9 times) under controlled load rotary bending fatigue tests. In the study, the fatigue crack initiation as well as fatigue crack growth behavior and the fracture mechanism were investigated through observations of fracture of boron steel surface(AISI 51B20).

• 연구논문집
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• s.28
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• pp.193-207
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• 1998

Fully dense THCN) based carbonitride ceramics were fabricated by pressureless sintering. During sintering, solid solutions were formed from the ceramic ingredients. The ceramics exhibited microvickers hardness of 1560-2050kgf/mm2, fracture toughness of 3.0-5.4 MPa $m^(1/2)$, and three point flexural strength of 645-1072 MPa. Some of the ceramics were shaped in a cutting tool, and the cutting performance was evaluated. In case of cutting SCM440 alloy steel, the ceramics showed better performance than the commercially available alumina-titanium carbide ceramic cutting tool. Considering the excellent productivity of pressureless sintering compared with other densification methods and their cutting performance, this new class of ceramics are very promising for wear resistant applications.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.1142-1143
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• 2006

Kinik Company pioneered diamond pad conditioners protected by DLC barrier ($DiaShield^{(R)}$ Coating) back in 1999 (Sung & Lin, US Patent 6,368,198). Kink also evaluated Cermet Composite Coating (CCC or $C^3$, patent pending) with a composition that grades from a metallic (e.g. stainless steel) interlayer to a ceramic (e.g. $Al_2O_3$ or SiC) exterior. The metallic interlayer can form metallurgical bond with metallic matrix on the diamond pad conditioner. The ceramic exterior is both wear and corrosion resistant. The gradational design of $C^3$ coating will assure its strong adherence to the substrate because there is no weak boundary between coating and substrate.

• Ceramist
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• v.9 no.6
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• pp.7-11
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• 2006

The status of structural ceramics in Japan is presented. Use of ceramics for structural components had been limited due to their brittleness, and the successful application was wear resistant parts such as thread guides and ceramic cutting tools up to around 1980. Since then, considerable work has been done for applying ceramics to mechanical parts, and automotive components made of silicon nitride were developed and commercialized in 1980s. Unfortunately, the application of silicon nitride to automotive engines is not so popular in these days. Instead, a variety of structural ceramics such as alumina, silicon carbide and zirconia have recently extended the market, and the expanded application includes vacuum process parts for manufacturing semiconductor and liquid crystal devices, refractory tubes for casting aluminum alloy, and dies for optical lens forming. In addition, cordierite honeycombs and diesel particulate filters are widely used in automobiles. In the present review, the recent application of structural ceramics to automobiles and industries in Japan is summarized.