• Journal of the Korean institute of surface engineering
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• v.24 no.1
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• pp.8-8
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• 1991

To investigate the effects of substrate on transverse-rupture strength(TRS) and bonding strength between substrate and TiC layer coated by CVD, two kinds of substrate (substrate A:WC-9.5wt%Co-MC*[low C], substrate B: WC-6wt% Co-MC*[high C] were studied in terms of Cobalt and C contents respectively. For preparation of test samples the coating parameters of deposition time, deposition temperature and deposition pressure were varied. The result show that the carbon contents in substrates have greater effects on the TRS of the CVD TiC coated cemented carbide than Co contents in substrates.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2002.04b
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• pp.8-8
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• 2002

서멧이란(Cermet) '세라믹 경질상과 금속 결합상의 복합체"를 의미하나 절삭 골구계에서는 좁은 의미의 "TiC 혹은 Ti(CN)을 바탕을 Ni,Co를 결합상으로 하는 초경재료"를 의미한다. 이런한 서멧은 전략 물질적 성격이 강한 Co,W로 구성된 WC-Co 초경 합금을 대체하기 위해 고안되었는ㄴ데 ㄴ놓은 경도와 고온에서의 화학적 안정성, 낮은 비중과 저렴한 원료 가격등이 장점이나 WC-Co에 비해 상대적으로 낮은 인성이 문제점으로 지적 되어왔다.TiC-Ni 서멧의 낮은 인성을 향상시키기 위해 Ti(CN) 고용체를 바탕으로 하고 제2ㅇ, 제3의 탄화물이나 질화물을 첨가하는 개발 연구가 과거 30여 년간 진행되어왔다. 그러나 많은 연구결과가 조성 개발 위주로 진행되어 왔고, 또 실험간의 불일치와 재현성 결여로 인해 보여진 여러 현상에 대한 보편적인 결론을 내리기 힘든 점이 있었다. 특히, 미세구조와 기ㅔ적 특성에 관한 통합적이고 조직적인 연구가 진행되지 못하였다. 이번 발표에서는 발표자 실험실에서 지난 8 년 간 행하여 온 실험 결과를 바탕으로 탄화물서멧에 나타나는 독특한 현상, 고용체 탄질화물의 열역학적 안정성, 서멧 재료의 유심구조, 표면 에너지 및 strain, 에너지가 미세 구조 형성에 미치는 영향, 그리고 표면층 형성 등 서멧 개발에 관한 중요 관심사에 대해 간단히 살펴보려고 한다.해 간단히 살펴보려고 한다.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.109-110
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• 2006

We have studied the effect of C/Ti atomic ratio of TiCx (x=0.5, 0.75 and 1.0) raw powder on the properties of the Ti-Mo-WTiC sintered hard alloy. The decrease of C/Ti atomic ratio accelerated the densification in the sintering process. The hardness was remarkably improved up to 1350HV with decreasing the C/Ti atomic ratio because of increase of TiCx phase volume content and its fine dispersion. From the results of electro-chemical tests in acid and 3% NaCl solutions, it was obvious that every alloy had excellent corrosion resistance, which meant about 200 times better than that of WC-Co cemented carbide.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2004.11a
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• pp.93-93
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• 2004

• Korean Journal of Materials Research
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• v.18 no.10
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• pp.558-563
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• 2008

TiAlN films were deposited on WC-5Co substrates with different buffer layers by D.C. magnetron sputtering. The films were evaluated by microstructural observations and measuring of preferred orientation, hardness value, and adhesion force. As a process variable, various buffer layers were used such as TiAlN single layer, TiAlN/TiAl, TiAlN/TiN and TiAlN/CrN. TiAlN coating layer showed columnar structures which grew up at a right angle to the substrates. The thickness of the TiAlN coating layer was about $1.8{\mu}m$, which was formed for 200 minutes at $300^{\circ}$. XRD analysis showed that the preferred orientation of TiAlN layer with TiN buffer layer was (111) and (200), and the specimens of TiAlN/TiAl, TiAlN/CrN, TiAlN single layer have preferred orientation of (111), respectively. TiAlN single layer and TiAlN/TiAl showed good adhesion properties, showing an over 80N adhesion force, while TiAlN/TiN film showed approximately 13N and the TiAlN/CrN was the worst case, in which the layer was destroyed because of high internal residual stress. The value of micro vickers hardness of the TiAlN single layer, TiAlN/TiAl and TiAlN/TiN layers were 2711, 2548 and 2461 Hv, respectively.

• Journal of the Korean institute of surface engineering
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• v.46 no.2
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• pp.68-74
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• 2013

For the coating of diamond films on WC-Co tools, a buffer interlayer is needed because Co catalyzes diamond into graphite. W and Ti were chosen as candidate interlayer materials to prevent the diffusion of Co during diamond deposition. W or Ti interlayer of $1{\mu}m$ thickness was deposited on WC-Co substrate under Ar in a DC magnetron sputter. After seeding treatment of the interlayer-deposited specimens in an ultrasonic bath containing nanometer diamond powders, $2{\mu}m$ thick nanocrystalline diamond (NCD) films were deposited at $600^{\circ}C$ over the metal layers in a 2.45 GHz microwave plasma CVD system. The cross-sectional morphology of films was observed by FESEM. X-ray diffraction and visual Raman spectroscopy were used to confirm the NCD crystal structure. Micro hardness was measured by nano-indenter. The coefficient of friction (COF) was measured by tribology test using ball on disk method. After tribology test, wear tracks were examined by optical microscope and alpha step profiler. Rockwell C indentation test was performed to characterize the adhesion between films and substrate. Ti and W were found good interlayer materials to act as Co diffusion barriers and diamond nucleation layers. The COFs on NCD films with W or Ti interlayer were measured as less than 0.1 whereas that on bare WC-Co was 0.6~1.0. However, W interlayer exhibited better results than Ti in terms of the adhesion to WC-Co substrate and to NCD film. This result is believed to be due to smaller difference in the coefficients of thermal expansion of the related films in the case of W interlayer than Ti one. By varying the thickness of W interlayer as 1, 2, and $4{\mu}m$ with a fixed $2{\mu}m$ thick NCD film, no difference in COF and wear behavior but a significant change in adhesion was observed. It was shown that the thicker the interlayer, the stronger the adhesion. It is suggested that thicker W interlayer is more effective in relieving the residual stress of NCD film during cooling after deposition and results in stronger adhesion.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2001.04a
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• pp.14-14
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• 2001

WC-Co 계의 입성장 억제는 현재 초경합금 분야에서 공학적으로 가장 중요한 이슈들 중의 하나이다 VC를 비롯한 입방정 탄화물이나 $Cr_3C_2$ 등의 여러 가지 탄화 물이 혼합되어 입성장 억제에 이용되는데 입성장 억제의 효과는 대략적으로 용해되는 탄화물의 양에 의존하고 있는 것으로 추정된다. 보다 효율적으로 입성장 억제를 실현하려면 입성장 기구를 명확히 할 필요가 있다. 최 등[1]은 VC가 WC 입자 표면 에서의 edge energy를 증가시켜서 2차원 핵생성의 에너지 장벽을 올리게 하고 이에 따라 입성장이 억제된다는 모델을 제안하였다. 이러한 모텔을 입증하기 위해서는 이론적으로만 예측이 가능한 edge energy보다 좀 더 명확한 물리적인 변수가 제시되어야 할 것이다. 여기서는 또 다른 계인 NbC- TiC-Co 계에서 NbC와 TiC의 버에 따른 입성장 거동과 입자의 형상간의 관계로부터 업성장과 edge energy 그리 고 edge energy와 입자 형상간의 관계를 알아보고 이로부터 좀 더 구체적인 의미 에서의 입성장 모텔과 입성장 억제기구를 제시하고자 한다.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.10a
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• pp.178-181
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• 2005

Quaternary Ti-Si-C-N coatings were deposited on WC-Co substrates by a hybrid coating system of arc ion plating (AIP) and sputtering techniques using Ti and Si targets, in an $Ar/N_2/CH_4$ gaseous mixture. The crystallinity, bending status, and microstructure of the Ti-Si-C-N coatings were measured by X-ray diffractometer (XRD) and X-ray photoelectron spectroscope (XPS), The micro-hardness of Ti(C,N) and Ti-Si-N coatings were about 30 and 40 GPa, respectively. As the Si was incorporated into Ti(C,N) coatings, the Ti-Si-C-N coatings having Si content of $8.9\;at.\%$ showed the maximum hardness value of about 55 GPa. In this work, the microstructure and mechanical properties of Ti-Si-C-N coatings were systematically investigated.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2003.10a
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• pp.89-94
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• 2003

Hard coatings are known to improve the performance of cutting tools in aggressive machining applications, such as high speed machining. New superhard Ti-Al-Si-W films, characterized by a nanocomposite nano-sized (Ti,Al,Si)N crystallites embedded in amorphous $Si_3 N_4$ matrix, could be successfully synthesized on WC-Co substrates by a hybrid coating system of arc ion plating(AIP) and sputtering method. The hardness of Ti-Al-Si-N film increased with incorporation of Si, and had the maximum value ~50 GPa at the Si content of 9 at.%, respectively. And the X-ray diffraction patterns of Ti-Al-Si-N films with various Si content is investigated. In this study, Ti-Al-Si-N coatings were applied to end-mill tools made of WC-Co material by a hybrid coating system. Cutting tests fir the high-hardened material (STD11,$H_R$)C62 and their performances in high speed cutting conditions were studied. Also, the tool wear and tool lift of Ti-Al-Si-N with various si(6, 9, 19) contents were measured.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2007.11a
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• pp.123-124
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• 2007

3성분계 Ti-Si-C 코팅은 PECVD 기술에 의해 WC-Co 기판에 합성되었다. 이 연구에서 Ti-Si-C코팅에서의 비정질 silicon carbide 상의 효과는 XRD, XPS, TEM에 의해 분석되었다. TiC 결정의 입자크기는 비정질 silicon carbide의 침투 현상 때문에 Si의 함유량이 증가됨에 따라 감소된다. Ti-Si-C 코팅은 5.2%의 Si함유량에서 나노크기의 nc-TiC결정과 비정질 a-SiC로 이루어져 있고 최고 경도 33GPa와 탄성율 330GPa를 각각 보여주고 있다. 이 수치들은 순수한 TiC(-21GPa, 260Gpa)보다 눈에 띄게 높아졌다.