• 열처리공학회지
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• 제5권4호
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• pp.215-223
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• 1992

This study has been performed to investigate into some effects of temperature, gas mixing ratio and time on the optical microstructure, hardness and wear characteristics of medium carbon alloy steel treated by plasma nitriding. The results obtained from the experiment are summarized as follows: (1) Optical micrographs of AISI 4140 steel plasma-nitrided by the double stage technique have revealed that the nitrided layer is composed of the compound layer and the diffusion layer. The variation in temperature at the first stage gives effects, on the formation of compound layer and the growth rate is shown to be relatively fast at $460^{\circ}C$. (2) The thickness of compound layer has been found to increase with increasing nitrogen percentage in the gas mixture and the holding time. It is therefore recommended that a shorter holding time and a lower nitrogen percentage are more effective to produce a tougher compound layer and a diffusion layer only. (3) X-ray diffraction analysis for AISI 4140 steel has shown that the compound layer consist of ${\gamma}^{\prime}-Fe_4N$ and ${\alpha}-Fe$ and that tough compound layer diffustion layer only can be obtained by the double stage plasmanitriding process. (4) There is also a tendency that the total hardened layer depth increases with increasing temperature, time and nitrogen percentage in the first stage during the double stage plasma nitriding. (5) The wear resistance of plasma nitrided specimens has been found thobe considerably increased compared to the untreated specimens and the amount of increment has appeared to increase further with increasing nitriding temperature, holding time and notrogen percentage of gas mixture in the first stage treatment.

• 전기화학회지
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• 제27권1호
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• pp.8-14
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• 2024

오스테나이트계 스테인리스강은 내식성 및 성형성이 양호하여 다양한 분야에 적용되며, 구리계의 합금을 용가재로 하는 브레이징을 통하여 다양한 형상의 제품으로 가공되어 활용되고 있다. 이때, 구리 기반의 용가재와 스테인리스강의 계면에서 갈바닉 셀을 형성하여 부식을 촉진할 수 있으며, 확산을 통해 스테인리스강에 고용 시 형성되는 구리 과다 영역(Cu-rich region)은 공식 발생의 기점이 되어 내식성을 저하시킨다. 본 연구에서는 브레이징이 적용된 스테인리스강의 내식성을 개선하고자, AISI 316L 스테인리스강에 암모니아 가스를 이용한 질화처리를 적용하였다. 질화처리한 시편은 처리 온도가 증가함에 따라 두께가 증가하고 표면 경도가 높아졌다. 동전위분극시험을 통해 내식성을 평가한 결과 질화층 내 고용된 질소의 용출 및 부동태 거동으로 모재대비 내식성이 개선되었지만 처리온도가 높아 크롬질화물(CrN) 분율이 증가하는 경우 내식성이 감소하였다.

• 한국표면공학회지
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• 제40권6호
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• pp.254-257
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• 2007

TiN coating on tool steel has been widely used for the improvement of durability of tools. In this work, radical nitriding(RN) is carried out on SKD61 at $450^{\circ}C$ for 5 hours in the ammonia gas pressure $2.7{\times}10^3\;Pa$. The TiN coating is carried out by arc ion plating(AIP) with the process parameters: arc power 150 A, bias voltage -50V, coating time 40 minutes and nitrogen gas pressure $4{\times}10^3\;Pa$. Hardness, elastic modulus, friction coefficient and adhesion of TiN coating on substrates of both TiN/SKD61 and TiN/RN SKD61 coatings are investigated comparatively. The primary crystalline faces of TiN surface are(200) and(111) for TiN/SKD61 and TiN/RN SKD61 respectively. In addition to the primary phase, Fe phase exists in TiN/SKD61 coating, but not in TIN/RN SKD61. The hardness of TiN/RN SKD61 is about 700 Hv, 250 Hv(56%) higher than that of TiN/SKD61 at the near interface of TiN and substrates. At the TiN surface, hardness of TiN/RN SKD61 is 2,149 Hv, 71 Hv(3%) higher than that of TiN/SKD61. The elastic modulus of TiN coating is improved to 26.7 GPa(6%) by radical nitriding. The adhesion is improved by the RN coating showing no spalling. buckling and chipping on the scratch test track which are shown on the non-RN TiN/SKD61.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2012년도 추계학술대회 논문집
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• pp.589-590
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• 2012

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 춘계학술강연 및 발표대회강연 및 발표논문 초록집
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• pp.39-40
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• 2006

• 한국진공학회:학술대회논문집
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• 한국진공학회 1996년도 제10회 학술발표회 논문개요집
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• pp.55-55
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• 1996

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2001년도 춘계학술발표회 초록집
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• pp.55-55
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• 2001

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part2
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• pp.863-863
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• 2006

• 한국재료학회지
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• 제13권3호
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• pp.174-179
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• 2003

Thin copper films were grown by electrodeposition on copper seed layers which were grown by sputtering of an ultra-pure copper target on tantalum nitride-coated silicon wafers and subsequently, cleaned in ECR plasma. The copper films were then subjected to ⅰ) vacuum annealing, ⅱ) rapid thermal annealing (RTA) and ⅲ) rapid thermal nitriding (RTN) at various temperatures over different periods of time. XRD, SEM, AFM and resistivity measurements were done to ascertain the optimum heat treatment condition for obtaining film with minimum resistivity, predominantly (111)-oriented and smoother surface morphology. The as-deposited film has a resistivity of ∼6.3 $\mu$$\Omega$-cm and a relatively small intensity ratio of (111) and (200) peaks. With heat treatment, the resistivity decreases and the (111) peak becomes dominant, along with improved smoothness of the copper film. The optimum condition (with a resistivity of 1.98 $\mu$$\Omega$-cm) is suggested as the rapid thermal nitriding at 400oC for 120 sec.

• 열처리공학회지
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• 제22권2호
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• pp.88-94
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• 2009

The effect of high temperature gas nitrding (HTGN) on the surface microstructure in pure Ti was investigated. Two phases of TiN and $Ti_2N$ appeared at the outmost surface, and the wide ${\alpha}$-Ti layer was formed at the next layer. On the other hand, the interior region, where the nitrogen was not permeated, exhibited ${\alpha}$'phase. The outmost surface of TiN and $Ti_2N$ showed the maximum hardness of 1000Hv, while the interior ${\alpha}$'phase was ${\sim}350$ Hv. The permeation depth of nitrogen increased with increasing the gas nitriding temperature and time. The nitrogen concentration of the surface layer seems to be over 12.7% at $1100^{\circ}C$.