• Title/Summary/Keyword: nitriding

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Mechanical Properties and cytotoxicity of nitrided 630 Stainless by ion nitriding (플라즈마 이온질화에 따른 STS 630의 기계적 특성과 세포독성에 관한 융합적 연구)

  • Hwang, Gab-Woon
    • Journal of the Korea Convergence Society
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    • v.10 no.11
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    • pp.241-246
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    • 2019
  • In this study, we have examined the possibility to improve the material properties and biocompatibility of the 630 stainless steel for the application of medical instruments. The evaluation of mechanical properties and biocompatibility of the 630 stainless steel were studied by aging, nitriding, SEM measurement, Vicker's hardness, tensile strength and MTT cytotoxicity using IGF cells, respectively. The results showed that the tensile strength and Vicker's hardness of 630 stainless steel was increased with aging and ion nitriding time. The cytotoxicities of the 630 stainless decreased compared with the 420 stainless on MTT cytotoxicity using IGF cells. Ion nitriding of 630 stainless led to an enhanced application of medical instruments and biocompatibility performance.

Characteristics of Fatigue Crack Initiation and Fatigue Strength of Nitrided 1 Cr- 1Mo-0.25V Turbine Rotor Steels

  • Suh, Chang-Min;Hwang, Byung-Won;Murakami, Ri-Ichi
    • Journal of Mechanical Science and Technology
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    • v.16 no.8
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    • pp.1109-1116
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    • 2002
  • To investigate the effect of nitriding layer on both fatigue crack initiation and fatigue life, turbine rotor steel ( IC.- 1Mo-0.25V steel) specimens were nitrided by the nitemper method and then put to a rotary bending fatigue test at room and elevated temperatures. In nitriding, temperature and time were controlled to obtain a different nitrided thickness. Microstructure analysis, micro-Victors hardness test, and scanning electron microscope observation were carried out for evaluating experiments. In results, the fatigue cracks of nitrided specimens were initiated at inclusion near the interface between nitrided layer and substrate, which showed fish-eye type appearance in fractograph. The fatigue life of nitrided specimens at every temperature was prolonged compared to that of the non-nitrided. However, there was not observable improvement in fatigue characteristics with the increase of a nitrided thickness.

Tribological Characteristics of Plasma Ion Nitriding Surface Treatment (플라즈마 이온 질화 표면처리의 윤활 및 마모 특성)

  • 좌성훈;김선교;박주승
    • Tribology and Lubricants
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    • v.12 no.4
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    • pp.60-70
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    • 1996
  • Scuffing and severe wear of the highly stressed sliding components have been very critical problems in the development of a rotary compressor. In order to improve durability and reliability of the compressor, plasma ion-nitriding was applied on the shaft and the vane surface. The effects of different treatment conditions on the mechanical and tribological properties of the ion-nitrided surfaces were investigated. Ion-nitrided surfaces showed better tribological performances than untreated surfaces. The best wear performance was observed when the shaft was nitrided in the condition of 450$\circ$C, 7 hours, $N_2:H_2=1:4$ gas mixture by forming a ductile nitrided layer which has $\gamma'$ phase microstructure. As nitrogen gas pressure increased, $\varepsilon$ phase layer was formed. This hard phase layer was observed to be more beneficial for the vane in reducing friction and wear.

Effect of Process Parameters on Plasma Nitriding Properties of $FeAl/SiC_p$ Composites ($FeAl/SiC_p$ 복합재료의 공정변수에 따른 플라즈마 질화 특성)

  • 박지환;김수방;박윤우
    • Journal of Powder Materials
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    • v.6 no.4
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    • pp.286-293
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    • 1999
  • This study was to analyse the relationship between process parameters of the sintered composite and plasma nitriding properties with pulsed DC plasma. Fe-40at%$SiC_p$ composites of full density were fabricated by hot pressing at 1100~$1150^{\circ}C$. Sintered Fe-40at%Al and Fe-40at%$Al/SiC_p$ alloys were nitrided under pulsed DC plasma. Excellent surface hardness in the FeAl alloys could be obtained by plasma nitriding. ($H_v$ :100gf, diffusion layer : 1100~$1450kg/mm^2$, matrix : 330~$360kg/mm^2$) The wear resistance of $FeAl/SiC_p$ composites were improved about by 4~6times than FeAl and nitrided $FeAl/SiC_p$ were improved about 2 times than $FeAl/SiC_p$ matrix.

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High Temperature Tribological Behaviors of Nitride Based Ceramic Coatings (나이트라이드계 세라믹 코팅의 고온 마모, 마찰거동)

  • 김장엽;임대순;이상로;백운승
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 1996.05a
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    • pp.83-86
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    • 1996
  • In this study, CrN, TiN and TiN + CrN coatings have treated onto the steel substrates by ion plating to improve their tribological behaviors. Some of the specimens were ion nitriding treated to study the effect of ion nitriding on wear behavior. The wear tests were performed with these specimens by ball-onplate type and disc-on-plate type wear tester. It was demonstrated that ion nitriding treatment improve wear resistance of the coatings. The results of high temperature wear tests indicated that the specimens coated with CrN were exhibited the better wear resistance properties than the specimens with TiN coatings

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Tensile and High Cycle Fatigue Properties of Ion-nitrided and Nitro-carburized SCr430B Steels (이온질화 및 질탄화 처리된 SCr430B 박판강의 인장 및 피로특성)

  • Park, S.H.;Lee, C.S.
    • Transactions of Materials Processing
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    • v.21 no.6
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    • pp.354-359
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    • 2012
  • Effects of a nitriding treatment on the tensile and high cycle fatigue properties were investigated by conducting ion-nitriding and gas nitro-caburizing treatments on the spheroidized SCr430B medium-carbon steel and performing tensile and tension-tension high cycle fatigue tests. The nitrided samples showed much lower strength and ductility compared to those in the initial as-spheroidized state and premature fracture occurred at the hardened layers. The micro-voids in the compound layer caused fatigue crack initiation. Thus, the removal of the compound layer with micro-voids remarkably improved the fatigue resistance to even beyond that of the as-spheroidized sample.

Syntheses of SiC and $SiC-Si_3N_4$ Powder from Jecheon Quartz (제천규석으로부터 SiC 및 $SiC-Si_3N_4$계 분말 합성)

  • 이홍림;배철훈;문준화
    • Journal of the Korean Ceramic Society
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    • v.23 no.1
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    • pp.67-73
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    • 1986
  • SiC and $SiC-Si_3N_4$ powder were synthesized via the carbiding and carbiding-nitriding reaction of Jecheon quartz respectively using graphite as a reducing agent. $\beta$-SiC+($\alpha$+$\beta$)-$Si_3N_4$ composite was obtained by the carbiding-nitriding reaction of Jecheon quartz-graphite mixture at 1, 35$0^{\circ}C$ in $H_2$ atmosphere. $\beta$-SiC+($\alpha$+$\beta$)-$Si_3N_4$ composite was obtained by the carbidint-nitriding reaction of Jecheon quartz-graphite mixture at 1, 35$0^{\circ}C$ in $N_2-H_2$ atmosphere. The ratio of $\beta$-SiC+($\alpha$+$\beta$)-$Si_3N_4$ content in a produced composite could be controlled by adjusting the reaction time and gaseous mixture.

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The Effects of Sputtering conditions in Pre Sputtering on the Formation Behavior of Nitride Layer in the Ion Nitriding of Stainless Steel (초기 스퍼터링조건이 스테인리스강의 이온질화시 지로하층 형성거동에 미치는 영향)

  • 최상진
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 1999.10a
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    • pp.197-203
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    • 1999
  • Stainless steels in general has passive film having strong corrosion resistance on surface. Therefore it must be necessarily removed by etching in mixing solution of sulfuric and chloric acid before Nitriding treatment. But in the ion nitriding, nitride layer was easily formed because passive film was removed without difficult by sputtering effect. The removal extent of these passive films was greatly effected by gas mixing ratios and pressure and holding times of pre sputtering factors in pre sputtering stage. As a results of experiment it has been known that pre sputtering pressure and holding time was not nearly effective on the formation behavior of nitride layer. But when A/H2 gas mixing ratios was 1/2 (vol%) was the most effective of the all pre sputtering conditions. It was resulted from the combination of mechanical reaction byArgon bombardment and chemical reaction by reduction of hydrogen on the passive film.

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A Study on the Corrosion Fatigue Characteristics of Ion-nitrided SCM4 Steel in Rotationg Bending (이온질화처리한 SCM4 강의 회전굽힘 부식피로 특성에 관한 연구)

  • Lee, Du-Yong;Woo, Chang-Gi
    • Journal of the Korean Society for Precision Engineering
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    • v.6 no.1
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    • pp.75-84
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    • 1989
  • This paper deals with the effect of $N_2$ and $H_2$gas mixture ratio and ion-nitriding time in the corrosion fatigue fracture behavior of ion-nitrided SCM4 steel with notch subject to rotary bending stress. The specimens were treated rapid water cooling after ion-nitriding at $500^{\circ}C$ Torr for 1 hour and 3 hours in gas mixtures of 80% $N_2$and 50% $N_2$. The fatigue limit and the fracture strength of corrosion fatigue depended on $N_2$gas quantity and ion-nitriding time. The ion-nitrided specimens showed about 88 .approx. 158% increase in the fracture strength of corrosion fatigue in $10^6$ cycles than non-nitrided specimens. The corrosion failure is due to corrosion pitting of the surface, and the propargation of cracks started at the surface into the core.

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The Effects Nitrogen percentage and Processing Time on the AISI 420 martensitic stainless steel during Plasma nitriding

  • Lee, In-Seop
    • Proceedings of the Korean Institute of Surface Engineering Conference
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    • 2015.11a
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    • pp.289-290
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    • 2015
  • In this experiment, nitriding treatment has been performed at $400^{\circ}C$ with various $N_2$ content and with changing processing time on AISI 420 martensitic stainless steel to investigate the expanded martensite layer (${\alpha}^{\prime}_N$ layer) formation behavior. Nitriding was implemented with changing $N_2$ content from 10% to 25% for 15 hrs and processing time was changed from 4hr to 15hr at 25% $N_2$ content. After treatment, the behavior of the ${\alpha}^{\prime}_N$ layer was investigated by optical microscopy, X-ray diffraction, and micro-hardness testing. Potentiodynamic polarization test was also used to evaluate the corrosion resistance of the samples. It was found that the surface hardness and ${\alpha}^{\prime}_N$ layer thickness increases with increasing $N_2$ percentage and processing time. Although their corrosion behaviors are worse than the bare sample.

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