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옥철호(Chul-Ho Ok),정인수(In-Su Jung),이규용(Kyu-Yong Lee) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.5
DLC coating on ceramics is very useful for high hardness and low-friction material. But adhesion of DLC films on ceramic is usually very poor. It is known that numerous parameters have influenced on the adhesion of DLC, including contamination and chemical bonding between the film and substrate. And these are related the mechanical properties of the DLC thin film. In this report, adhesion of DLC on ceramic has been improved by applying silicon metal intermediate layers using plasma immersion ion deposition(PIID) technique for tribological purposes. We have investigated the mechanical, chemical and structural properties of amorphous DLC thin films suited to these requirements. This DLC coated specimens have been tested under a wider range of temperature conditions, from room 24℃ up to 400℃ in dry air to see the survivability of the DLC coatings. We found that the chemical composition of bonding layer and also the thickness of bonding layer itself effect significantly on the adhesion of the DLC coating on Al2O3. Wear tested specimens were analyzed using SEM to characterize the worn surfaces and the cross sections of the DLC films.
Al 6061 에 코팅된 TiAlN 박막의 기계적 성질에 미치는 Process의 영향
정인수(In-Su Jung),옥철호(Chul-ho Ok),이규용(Kyu-Yong Lee) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.5
Aluminum alloy is a very useful material in terms of light weight and high relative strength compared to any other metallic materials. However, low hardness of this material makes limitations in its application. We have been successfully developed TiAlN thin film of hard coating on Al6061 as a promising alternative to hard and light weight material for the application of high speed rotating machine elements. In this application, the adhesion of hard coating to base material is one of the most important parameter. TiAlN coatings were deposited by DC magnetron sputtering method at various nitrogen partial pressures of the coating process using Ti based alloy cathode of which composition is 90wt.%Ti, 6wt.%Al and 4wt.%V. This material was chosen from a commercially available grade23 engineering material and the affinity of Al element in target and base material. The coating experiments were carried out at various nitrogen flow rate from 0.75 to 0.95 sccm with constant Ar flow rate of 5 sccm. In this report, the influence of stoichiometry of nitrogen on the mechanical properties of TiAlN coating was investigated. By using this experiments, we found that the hardness of TiAlN which was recognized through the XRD analysis and scratch test is related to nitrogen to argon ratio.
플라즈마 이온증착 기술을 이용한 스테인리스강의 질화처리에 관한 연구
박일수(Il-Soo Park),옥철호(Chul-Ho Ok),김재돌(Jae-Dol Kim) 한국마린엔지니어링학회 2007 한국마린엔지니어링학회 학술대회 논문집 Vol.2007 No.-
Plasma immersion ion beam (PUB) nitriding process is an environmentally benign and cost-effective process, and offers the potential of producing high dose of nitrogen ions in a way of simple, fast and economic technique for the high plasma flux treatment of large surface area with nitrogen ion source gas. In this report PUB nitriding technique was used for nitriding on austenite stainless steel of AISI304 with plasma treatment at 250~500℃ for 4 hours, and with the working gas pressure of 2.67 × 10?¹ Pa in vacuum condition. This PUB process might prove the advantage of the low energy high flux of ion bombardment and enhance the tribological or mechanical properties of austenite stainless steel by nitriding. Furthermore, PIIB showed a useful surface modification technique for the nitriding an irregularly shaped three dimensional workpiece of austenite stainless steel and for the improvement of surface properties of AISI 304, such as hardness and strength.
Peripheral T Cell Lymphoma에 선행하여 발생한 호산구성 근막염 유사 반응
구기환 ( Ki Hwan Ku ),김희규 ( Hee Kyoo Kim ),이호섭 ( Ho Sup Lee ),김근태 ( Geun Tae Kim ),옥철호 ( Chul Ho Ok ),정만홍 ( Maan Hong Jung ),장희경 ( Hee Kyung Chang ),천봉권 ( Bong Kwon Chun ) 대한천식알레르기학회 2010 천식 및 알레르기 Vol.30 No.3
Eosinophilic fasciitis (EF) is characterized by scleroderma-like skin lesions, peripheral eosinophilia and hypergamma-globulinemia. While EF is generally benign course, it may precede hematologic malignancy or Hodgkin`s disease, association with peripheral T-cell lymphoma (PTCL) is extremely rare. A 49-year-old man with edema and induration of both distal extremities. Peripheral blood eosinophil count was 2,530/μL. We suspected EF, however, could not performed histological diagnosis due to his refusal. After 6 months, he was suffered of abrupt fever, weight loss and general weakness for 1 months. Erythematous nodular papules of skin and enlarged inguinal lymph nodes were noted. Biopsies from skin and lymph node showed peripheral T cell lymphoma. (Korean J Asthma Allergy Clin Immunol 2010;30:233-236)