• 제목/요약/키워드: Steel-surface layer

검색결과 682건 처리시간 0.033초

미끄럼운동시 TiN코팅볼과 스틸디스크의 미끄럼접촉면에 형성되는 산화막의 영향을 고려한 마찰천이선도 작성에 대한 연구 (Friction Transition Diagram Considering the Effects of Oxide Layer Formed on Contact Parts of TiN Coated Ball and Steel Disk in Sliding)

  • 조정우;박동신;이영제
    • 대한기계학회논문집A
    • /
    • 제27권3호
    • /
    • pp.335-342
    • /
    • 2003
  • In this study, the effects of oxide layer formed on the contact parts of TiN coated ball and steel disk in sliding are investigated. Also wear mechanism to from the oxide layer and the characteristics of the oxide layer formation are investigated. AISI 52100 steel ball is used for the substrate of coated ball specimens. Two types of coated ball specimens were prepared by depositing TiN coating with 1 and 4 ${\mu}{\textrm}{m}$ in coating thickness. AISI 1045 steel is used for the disk type counter-body. To investigate the effect of oxide layer on the contact parts of the two materials, the tests were performed both in air for forming oxide layer on the contact parts and in nitrogen environment to avoid oxidation. And to study the effects of surface roughness of counter-body, TiN coating thickness and contact load of sliding test on the characteristics of oxide layer formation on counter-body, various tests were carried out. From the results, the friction characteristics between the two materials was predominated by iron oxide layer that formed on wear track on counter-body and this layer caused the high friction. And the formation rate of the oxide layer on wear track increased as the real contact area between the two materials increased as the contact load increased, the TiN coating thickness decreased and the surface of counter-body smoothened.

고분자 전해질 연료전지용 분리판으로서 스테인리스강에 HVOF 용사된 AISI316-WC 코팅층 (HVOF Thermal Sprayed AISI316-WC Coating Layer on Stainless Steel for PEMFC Bipolar Plate)

  • 남대근
    • 신재생에너지
    • /
    • 제4권1호
    • /
    • pp.31-36
    • /
    • 2008
  • Stainless steels have been widely considered as metallic bipolar plates, due to their passive surface film, which is good for corrosion resistance. However, the high resistivity of the passive film increases interfacial contact resistance between the bipolar plates and the electrodes. Stainless steels thermal spray coated with a mixture of tungsten carbide and stainless steel powders showed that the coated layer safely combined with the matrix but they suffered many internal defects including voids and cracks. Many cracks were formed in the coated layer and the interface of the matrix and the coated layer during the rolling process. The coated and rolled stainless steels showed lower interfacial contact resistance and corrosion resistance than bare stainless steel because of low resistivity of tungsten carbide and numerous defects, which caused crevice corrosion, in the coated layer.

  • PDF

고분자 전해질 연료전지용 스테인리스강 분리판의 HVOF AISI316-WC 코팅층 특성 (Characteristic of HVOF AISI316-WC Coating Layer on Stainless Steel Separator for PEMFC)

  • 남대근;강남현;박영도;김영석
    • 한국신재생에너지학회:학술대회논문집
    • /
    • 한국신재생에너지학회 2008년도 추계학술대회 논문집
    • /
    • pp.1-5
    • /
    • 2008
  • Stainless steels have been widely considered as metallic separators, due to their passive surface film, which is good for corrosion resistance. However, the high resistivity of the passive film increases interfacial contact resistance between the separators and electrodes. Stainless steels thermal spray coated with a mixture of tungsten carbide and stainless steel powders showed that the coated layer safely combined with the matrix but they suffered many internal defects including voids and cracks. Many cracks were formed in the coated layer and the interface of the matrix and the coated layer during the rolling process. The coated and rolled stainless steels showed lower interfacial contact resistance and corrosion resistance than bare stainless steel because of low resistivity of tungsten carbide and numerous defects, which caused crevice corrosion, in the coated layer.

  • PDF

The Effects of Gas Compositions During Post Nitriding on the AISI 316L Stainless Steel after Plasma Carburizing

  • Lee, Insup
    • 한국표면공학회지
    • /
    • 제48권6호
    • /
    • pp.269-274
    • /
    • 2015
  • In this experiment, post-nitriding treatment was performed at $400^{\circ}C$ on AISI 316 stainless steel which was plasma carburized previously at $430^{\circ}C$ for 15 hours. Plasma nitriding was implemented on AISI 316 stainless steel at various gas compositions (25% $N_2$, 50% $N_2$ and 75% $N_2$) for 4 hours. Additionally, during post nitriding Ar gas was used with $H_2$ and $N_2$ to observe the improvement of surface properties. After treatment, the behavior of the hybrid 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. Meanwhile, it was found that the surface hardness increased with increasing the nitrogen gas content. Also small percentage of Ar gas was introduced in the post nitriding process which improved the hardness of the hardened layer but reduced the corrosion resistance compared with the carburized sample. The experiment revealed that AISI 316L stainless steel showed better hardness and excellent corrosion resistance compared with the carburized sample, when 75% $N_2$ gas was used during the post nitriding treatment. Also addition of Ar gas during post nitriding treatment degraded the corrosion resistance of the sample compared with the carburized sample.

Corrosion Inhibition Screening of 2-((6-aminopyridin-2-yl)imino)indolin-3-one: Weight Loss, Morphology, and DFT Investigations

  • Nadia Betti;Ahmed A. Al-Amiery
    • Corrosion Science and Technology
    • /
    • 제22권1호
    • /
    • pp.10-20
    • /
    • 2023
  • Because of its inexpensive cost, mild steel is frequently employed as a construction material in different industries. Unfortunately, because of its limited resistance to corrosion, a protective layer must be applied to keep it from decaying in acidic or basic environments. The presence of heteroatoms, such as nitrogen, oxygen, and pi-electrons in the Schiff base could cause effective adsorption on the mild steel surface, preventing corrosion. The weight loss method and scanning electron microscopy (SEM) were used to investigate the inhibitory effects of APIDO on mild steel in a 1 M hydrochloric acid environment. The efficiency of inhibition increased as the inhibitor concentration increased and decreased as the temperature increased. The SEM analysis confirmed that the corrosion inhibition of APIDO proceeded by the formation of an organic protective layer over the mild steel surface by the adsorption process. Simulations based on the density functional theory are used to associate inhibitory efficacy with basic molecular characteristics. The findings acquired were compatible with the experimental information provided in the research.

Zn-Al-Mg 합금도금강판의 헤어라인 처리가 표면흑색화 및 열확산도에 미치는 영향 (Effects of hairline treatment on surface blackening and thermal diffusion of Zn-Al-Mg alloy-coated steel sheet)

  • 박진성;윤덕빈;김상헌;김태엽;김성진
    • 한국표면공학회지
    • /
    • 제56권1호
    • /
    • pp.69-76
    • /
    • 2023
  • The effects of hairline treatment on surface blackening and thermal diffusion behaviors of Zn-Al-Mg alloy coated steel sheet were evaluated by the three-dimensional surface profiler and laser-flash technique. The metallographic observation of coating damages by hairline treatments showed that several cracks were initiated and propagated along the interface between primary Zn/eutectic phases. As the hairline processing became more severe, the crack occurrence frequency in eutectic phase of coating layer and the surface roughness increased, which had a proportional relationship with the level of blackening on the coating surface. In addition, the higher interfacial areas of the blackened coating surface, caused by the hairline process, led to an increase in thermal diffusivity and conductivity of the coated steel sheet. On the other hand, when the coating damage by hairline treatment was excessive and the steel substrate was exposed, there was little difference between the thermal diffusivity/conductivity of the untreated sample though the blackening degree was higher than that of untreated sample. This work suggests that the increase in the surface areas of the coating layer without exposure to steel substrate through hairline treatment can be one of the effective technical strategies for the development of Zn-Al-Mg alloy coated steel sheets with higher blackening level and thermal diffusivity.

SCM440강의 마이크로 펄스 플라즈마 질화 및 후산화처리시 질소농도에 따른 특성변화 (Effects of Nitrogen Contents on the Nitriding Characteristics of the Micro-Pulse Plasma and Post Oxidation Treated SCM440 Steel)

  • 이상기;정인상;이재식
    • 열처리공학회지
    • /
    • 제12권2호
    • /
    • pp.117-128
    • /
    • 1999
  • This study was carried out to investigate the surface characteristics of SCM440 steel nitrided with various nitrogen contents for 7 hours at $520^{\circ}C$ by using micro-pulse plasma nitriding apparatus of hot wall type. The effects of oxidation treatment was also investigated on plasma nitrided in 30% nitrogen and post oxidized SCM440 steel at $500^{\circ}C$ in $H_2O$ atmosphere. The ${\gamma}^{\prime}-Fe_4N$ and ${\varepsilon}-Fe_{2-3}N$ phases were detected in compound layer of the nitrided steel. As the content of nitrogen in plasma gas increased with 30, 50, 70% on the micro-pulse plasma nitriding for SCM440 steel, the thickness of compound, diffusion layer and the surface hardness were increased. From the wear test results, the best wear resistance was appeared in the condition of ductile ${\gamma}^{\prime}-Fe_4N$ phase formed specimen at 30% nitrogen, whereas that of the treated with 50% and 70% nitrogen decreased owing to the exfoliation of brittle ${\varepsilon}-Fe_{2-3}N$ phase in the compound layer. On the nitrided and subsequently oxidized SCM440 steel, the surface layer consisted of $Fe_3O_4$, ${\gamma}^{\prime}-Fe_4N$, and ${\varepsilon}-Fe_{2-3}N$ phases. In these treatments, the dissolution of nitrides affect hardness and hardening depth in compound and diffusion layers. For the nitrided in 30% nitrogen and post oxidized specimen at $500^{\circ}C$ for 1 hour, the wear resistance was lower than that of the only nitrided one in 30% nitrogen but higher than those of the nitrided ones in 50 and 70% nitrogen.

  • PDF

플라즈마 침탄한 저탄소 Cr-Mo강의 피로특성에 관한 연구 (A study on fatigue properties of plasma carburized low carbon Cr-Mo steel)

  • 박경봉;신동명;이창열;이경섭
    • 한국재료학회지
    • /
    • 제10권7호
    • /
    • pp.505-514
    • /
    • 2000
  • 플라즈마 침탄한 저 탄소 Cr-Mo 강(0.176C-1.014Cr-0.387Mo)의 침탄 특성과 피로성질을 고찰하였다. 플라즈만 침탄한 시편의 유효경화깊이는 가스 침탄한 시편에 대해 상대적으로 침타나시간이 짧고 침탄온도가 낮음에도 불구하고 50%정도까지 증가되었다. 플라즈만 침탄시 유효경화깊이의 증가는 표면탄소농도의 증가와 같은 경향을 보였으며, 표면탄소농도의 증가와 같은 경향을 보였으며, 표면탄소농도의 증가율이 침탄시간의 증가에 따라 감소하였다. 플라즈만 침탄간의 피로한도는 가스 침탄강의 경우보다 높았다. 이를 표면근처의 미세구조, 경화깊이 잔류, 오스테나이트와 압축잔류응력으로 조사한 결과 경화깊이와 압축잔류응력의 차이가 거의 없었다. 따라서 플라즈만 침탄의 피로강도 향상은 가스침탄에 비해 표면이 상승층이 저감되어 표면에서의 미소균열의 발생 및 초기 균열 전파과정이 지연 되어진 것으로 판단된다. 파단면 관찰결과 표면에서 균열이 시작되고 플라즈마 침탄의 경우 입내파괴가 현저하였다.

  • PDF

17-4 PH Stainless 강의 질소침투 열처리 (A Study on the Nitrogen Permeation Treatment of 17-4 PH Stainless Steel)

  • 유대경;성장현
    • 열처리공학회지
    • /
    • 제19권2호
    • /
    • pp.83-89
    • /
    • 2006
  • The surface phase changes, the hardness variations, the nitrogen contents and the corrosion resistances of 17-4 PH stainless steel have been investigated after nitrogen permeation(solution nitriding) at a temperature ranges from $1050^{\circ}C$ to $1150^{\circ}C$ The phases appeared at the nitrogen-permeated surface layer were shown to martensite plus austenite and austenite, depending on the variation of nitrogen and chromium contents. And the surface hardness was also depended on the phases appeared at the surface layer from 370 Hv to 220 Hv. The precipitates exhibited at the nitrogen-permeated surface layer were niobium nitride, niobium chromium nitride and carbo-nitride in the austenite and martensite matrices. The surface nitrogen contents were followed by the Cr contents of the surface layers, representing 0.55% at the temperatures of $1050^{\circ}C$ and $1150^{\circ}C$ respectively, and 0.96% at $1100^{\circ}C$ at the distances of $60{\mu}m$ from the outmost surface. From the comparison of the corrosion resistances between nitrogen-permeated and solution-annealed steels, nitrogen permeation remarkably improved the corrosion resistance in the solution of 1 N $H_2SO_4$ due to the increase of nitrogen content in the surface austenite phase.

아크 용사법에 의한 강재표면에의 Aluminum침수 및 내식, 경화성 피막형성에 관한 연구 (A study on the Al cementation and formation of corrosion-resisting, hardening layer on the steel surface by the arc spray method)

  • 김영식;배차헌;오재환;문경만
    • Journal of Advanced Marine Engineering and Technology
    • /
    • 제13권2호
    • /
    • pp.64-77
    • /
    • 1989
  • In this study, the experiments were carried out for the purpose of establishment of aluminium cementation to steel surface by diffusible heat treatment after making the coated film onto the substrate by arc spray method. Also, the microstructure and mechanical properties of the cementation layer produced by this study were inspected for various heat treatment and spraying conditions. Main results obtained are as follow ; 1. The coating film characteristics which have excellent errosion-resistance, high temperature oxidation-resistance are obtained by aluminium penetration heat treatment after making the sprayed aluminum coating film onto the steel substrate. 2. Aluminium diffusion penetration takes place at higher temperature than 660.deg.C, and the more heat treatment time and the higher heat treatment temperature adopted, the deeper diffusion layer obtained. 3. Insert gas arc spraying using argon gas as the carrier gas higher improvement of mechanical property than that of compressed air environment. 4. The coating film characteristics appeared to be improvement of adhesive property, porosity plugging effect by heat treatment in air environment.

  • PDF