• Title/Summary/Keyword: NiMo

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Characterization of Oxide Scales Formed on Fe3Al, Fe3Al-Cr, Fe3Al-Cr-Mo, Ni3Al and Ni3Al-Cr Alloys (Fe3Al, Fe3Al-Cr, Fe3Al-Cr-Mo, Ni3Al 및 Ni3Al-Cr 합금표면에 형성된 산화물 특성분석)

  • Shim, Woung-Shik;Lee, Dong-Bok
    • Korean Journal of Materials Research
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    • v.12 no.11
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    • pp.845-849
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    • 2002
  • Alloys of $Fe_3$Al, $Fe_3$Al-6Cr, $Fe_3$Al-4Cr-1Mo, $Ni_3$Al, and $Ni_3$Al-2.8Cr were oxidized at $1000^{\circ}C$ in air, and the oxide scales formed were studied using XRD. SEM, EPMA, and TEM. The oxide scales that formed on $Fe_3$Al-based alloys consisted primarily of $\alpha$-$Al_2$$O_3$ containing a small amount of dissolved Fe and Cr ions, whereas those that formed on $Ni_3$Al-based alloys consisted primarily of $\alpha$-$Al_2$$O_3$, together with a small amount of $NiAl_2$$O_4$, NiO and dissolved Cr ions. For the entire alloys tested, nonadherent oxide scales formed, and voids were inevitably existed at the scale-matrix interface.

A Study On the Sand Wear Resistance and Formation Behavior of Boride Layer Formed on Ni-Cr-Mo Steel by Plasma Paste Boronizing Treatment (Plasma Paste Boronizing법에 의한 Ni-Cr-Mo강의 붕화물층 생성거동과 내 토사마모특성에 관한 특성)

  • Cho J. H;Park H. K;Son K. S;Yoon J. H;Kim H. S;Kim C. G
    • Korean Journal of Materials Research
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    • v.14 no.1
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    • pp.52-58
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    • 2004
  • The surface property and formation behavior of a boride layer formed on Ni-Cr-Mo steel in a plasma paste boronizing treatment were investigated. The plasma paste boronizing treatment was carried out at 973~1273 K for 1-7 hrs under the gas ratio of Ar:H$_2$ (2:1). The thickness of the boride layer increased with increasing temperature and time in the boronizing treatment. The cross-section of the boride layer was a tooth structure and the hardness was Hv 2000~2500. XRD analysis revealed that the compound was identified as FeB, $Fe_2$B, and mixed phase of FeB/$Fe_2$B in the boride layer formed at 973~1073 K, 1173K, and 1273K, respectively. The Ni-Cr-Mo alloy boronized at 1173-1273 K showed the best excellent wear resistance against the sand. As a results of corrosion test in 1 M $H_2$$SO_4$ solution, $Fe_2$B formed on the matrix alloy exhibited higher corrosion resistance than FeB.

A Study on Tribological Characteristics for High Temperature Alloy Steel with Ni-Cr-Mo-V (Ni-Cr-Mo-V 내열강의 마찰마모 특성 연구)

  • Lim, Ho Gi;Bae, Mun Ki;Kim, Tae Gyu
    • Journal of the Korean Society for Heat Treatment
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    • v.29 no.6
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    • pp.284-291
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    • 2016
  • High temperature alloy steel such as Ni-Cr-Mo-V material has excellent properties of high strength and high heating resistance. It has been used for several military weapon components such as gun barrel of a warship, turbine rotor and turbine disk for nuclear power plant. Being curious about this material required excellent wear resistance and durability in extreme environmental conditions. A dry wear test at the ambient air and Ar gas conditions in the room temperature were performed in this study. What's more a lubricant wear test at different temperature was conducted. In addition that DLC was coated on Ni-Cr-Mo-V alloy steel substrate with a thickness of $3{\mu}m$, a property of it was compare with lubricant conditions. All the coefficient of friction and wear volume, comparing with DLC coated specimens. The test parameters were selected as follows: 10 N for normal load; 80 rpm for sliding wear speed; and 300 m for the sliding wear distance.

Effect of Heat Treatment on the Microstructures and Properties of HVOF Sprayed Ni-Cr-W-Mo-B Alloy Coatings (초고속화염용사법으로 제조된 Ni-Cr-W-Mo-B 합금 코팅의 미세조직과 특성에 미치는 열처리 효과)

  • 민경오;이창희
    • Journal of Welding and Joining
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    • v.18 no.6
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    • pp.48-54
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    • 2000
  • The corrosion properties of Ni-Cr-W-Mo-B alloy sprayed by the high velocity oxy-fuel spraying (HVOF) was studied as a function of heat treatment by using both potentiodynamic polarization and immersion tests in the H₂SO₄ solution. The mechanical property was also evaluated by a microhardness tester. Microstructural characteristics of te as-sprayed and annealed coatings at 550, 750 and 950℃ have been analyzed by means of OM, XRD, SEM and TEM. The results showed that the corrosion resistance was improved by increasing the annealing temperature. As-sprayed coating had metastable and heterogeneous phases such as amorphous, nanocrystalline and very refined grain and precipitates, which induced a localized corrosion. The localized corrosion occurred preferentially at the unmelted particles which were composed of Ni matrix and Cr, W and Mo riched phase segregated in the boundaries. As annealing temperature was increased, the microstructure had shown some changes - reduction of porosity and s[plat boundary decomposition and crystallization of amorphous/nanocrystalline phases, grain coarsening,, formation and growth of precipitates such as {TEX}$M_{23}C_{6}${/TEX} and {TEX}$M_{7}C_{3}${/TEX}. In addition, the compositional difference between matrix and boundary phases gradually disappeared, which changed the corrosion type from localized corrosion to general corrosion and thus enhanced corrosion resistance.

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A Study on the Properties in Friction Weldability of Ni-Cr-Mo and SM45C (Ni-Cr-Mo과 SM45C의 마찰용접특성(摩擦熔接特性)에 관한 연구(硏究))

  • Lim, Hyung-Taek;Min, Taeg-Ki
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.16 no.6
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    • pp.29-36
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    • 2007
  • The present study examined the mechanical properties of the friction welding of Ni-Cr-Mo to SM45C. Friction welding was conducted at welding conditions of 2,000 rpm, friction pressure of 100MPa, friction time of 0.8, 1.0, 1.2, 1.4, 1.6, 1.8, 2.0 seconds, upset pressure of 150MPa, and upset time of 3.0 seconds. When the friction time was 1.6 seconds, the maximum tensile strength of the friction weld happened to be 1,020MPa, which is 120% of the base material's tensile strength(850MPa). At the same condition, the maximum shear strength was 438MPa, which is equivalent to 103% of the base material's shear strength(425MPa). At the same condition, the maximum vickers hardness was Hv490 at Ni-Cr-Mo nearby weld interface, which is higher Hv40 than condition of the friction time 0.8 seconds, and the maximum vickers hardness was Hv305 from weld interface of SM45C, which is higher Hv12 than condition of the friction time 0.8 seconds. The results of microstructure analysis show that the structures of two base materials have fined and rearranged along a column due to heating and axial force during friction, which has affected in raising hardness and tensile strength.

A Study of Simultaneous Hydrodesulfurization and Hydrocracking Reactions over CoMo, NiMo/ZSM-5 Catalysts (CoMo, NiMo/ZSM-5 촉매상에서 동시적인 수첨탈황과 수소화 분해반응에 관한 연구)

  • 정우식;고을석;김경림
    • Journal of Korean Society for Atmospheric Environment
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    • v.9 no.2
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    • pp.140-146
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    • 1993
  • CoMo, NiMo/ZSM-5 catalysts were prepared at Si/Al ratios of 100, 200 and characterized by TGA, XRD and SEM. Simultaneous hydrocracking of n-heptane and hydrodesulfurization of DBT were studied over these catalysts at the ranges of temparatures between 400$^\circ$C and 500$^\circ$C, pressure of 30 $\times 10^5$ Pa and contact time of 0.02g cat. hr/ml feed in a fixed bed flow reactor. It was shown that the hydrocracking activity of n-heptane increased in the order of NM 100, CM 100, NM 200 and CM 200 catalysts. It was also shown that the Hydrodesulfurization activity of DBT increased in the order of CM 200, NM 200, CM 100 and NM 100 catalysts and these results were thought to be that the increase of acidity of catalysts might increase hydrocracking activity of these catalysts but deactive those simultaneously. In this study it was shown that CM 100 and NM 200 were active catalysts in simultaneous hydrodesulfurization of DBT and hydrocracking of n-heptane reactions.

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The Effects of Molybdenum and Nickel Addition on Impact Toughness of Austempered Ductile Cast Iron (오스템퍼 구상흑연주철의 충격인성에 미치는 Mo 및 Ni의 영향)

  • Park, Yoon-Woo;Chang, Hyun-Ku
    • Journal of Korea Foundry Society
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    • v.8 no.4
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    • pp.459-466
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    • 1988
  • This study was carried out in the austempering temperature and time after Ni, Mo addition in purpose of modification of impact toughness of austempered ductile irons. Addition of alloy element and austempering treatment of $900^{\circ}C$ 60 minutes followed by $300^{\circ}C$, $350^{\circ}C$ and $400^{\circ}C$ for 60 minutes, in this case impact value was increased by ideal mixed structure. But impact value was decreased when holing time is 120minutes, this is attributed to segregation and carbide precipitation from high carbon austenite. Highest impact value was obtained by $350^{\circ}C$ (Mo-addition) and $400^{\circ}C$ (Ni-addition). This phenomena was caused by presence of remained austenite. At all austempering temperature,, Ni-added specimen showed higher impact values than that of Mo-added specimen. And hardness property was affected by austempering temperature and holding time rather than amounts of alloying element.

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The influence of spraying conditions to the coating layer properties of Fe-Cr-Ni-Mo-Si-B alloy using the HVOF (HVOF를 이용한 Fe-Cr-Ni-Mo-Si-B계 고성능 합금 용사층의 특성에 미치는 용사조건의 영향)

  • 권기봉;조대형;장영권;백영남
    • Journal of the Korean institute of surface engineering
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    • v.35 no.1
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    • pp.5-10
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    • 2002
  • This study was performed to investigate the influence of spraying condition to the coating layer properties of Fe-Cr-Ni-Mo-Si-B alloy using the HVOF. The investigations, such as thickness measurement, surface roughness, hardness, friction coefficient, resistance of corrosion were carried out. Matrix is prepared by gritting and coating layer is made of Fe-Cr-Ni-Mo-Si-B alloy powder using HVOF. Alumina gritting layers are superior to steel gritting layers. The less spaying distance, the more coating layer properties confirmed. The optimum spraying condition, in this study, was proved as 13inch spraying distance with feed rate 350rpm (78g/min).

A Study on the Low Temperature Fracture Toughness of Ion-nitrided Ni-Cr-Mo Steel (이온 실화처리한 Ni-Cr-Mo강의 저온파괴인성에 관한 연구)

  • 오세욱;윤한기;문인철
    • Journal of Ocean Engineering and Technology
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    • v.1 no.2
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    • pp.101-112
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    • 1987
  • Fracture toughness characterization in the transition region is examined for heat-treated and ionnitrided Ni-Cr-Mo steel. After heat treatment for the specimens of Ni-Cr-Mo steel, organizations of specimens-specimens which are heat-treated and ion-nitrided for 4 hours at 500 .deg. C and 5 torr in 25%N/dub 2/-75%H/sub 2/mixed gas-, hardness variety, and X-ray diffraction pattern of the ion-nitriding compound layer are observed. Fracture toughenss test of unloading compliance method were conducted over the regions from room trmperature to -70.deg. C. The compound layer was consisted of r'=Fe/sub 4/N phase and ion-nitrided layer's depth was 200mm from surface. The transition regions of heat-treated and ion-nitrided specimens were about -30.deg. C and -50.deg. C, respectively. The transition region of ion-nitrided specimens is estimated less than that of heat-treated one, and this is the effect of ion-nitriding.

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Quantitative Investigation of Grain Growth in Carbide Added(Mo$_2$C, ZrC and WC) to TiC-Ni Matrix Cermets

  • Kim, Soon-Ho
    • International Journal of Precision Engineering and Manufacturing
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    • v.5 no.1
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    • pp.19-26
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    • 2004
  • The growth of solid particles in TiC-XC-2vo1.% and TiC-XC-30vo1.% Ni alloys, (where X=Zr, W or Mo) was fitted to the equation of the form $d^3$-${do}^3$=Kt during the liquid phase sintering at 1,673K. Also, the grain growth behavior decreased markedly with the addition of ${MO}_2$C or WC and increased with the addition of zrC. The contiguity was greater in the alloys with a smaller growth rate constant and especially, decreased by increasing the Ni content in the TiC-${MO}_2$C-Ni alloy. In addition, the effect of the addition of carbide on the grain growth of 2 vo1.% Ni alloys was found to be similar to that of 30vo1.% Ni alloys. Consequently, the grain growth mechanism cannot be explained by the usual solution / reprecipitation process, but can be explained in terms of a new growth velocity equation, which includes the effects of contiguous carbide grain boundaries in restricting the overall grain growth, as well as the area of the solid / liquid interface in the alloy.