• 대한용접접합학회:학술대회논문집
• /
• 대한용접접합학회 2009년 추계학술발표대회
• /
• pp.38-38
• /
• 2009

36 percent nickel-iron alloy possesses a useful combination of low thermal expansion, moderately high strength and good toughness at temperatures down to that of liquid helium, $-269^{\circ}C$. These propeties coupled with good weldability and desirable physical properties make this alloy attractive for many cryogenic applications such as the cargo containment system in Liquefied Natural Gas carriers and pipes for low temperature. Generally, welding method of the 36% nickel-iron is applied with the manual and autogeneous GTAW. Lately white spots have been observed on the some autogeneous GTA welds of them. But the white spot formation have not been studied yet. This paper covers the analysis results of the white spots formation as changing welding variables.

• 한국표면공학회지
• /
• 제38권4호
• /
• pp.156-162
• /
• 2005

Nickel-iron nanocrystalline alloys with different compositions and grain sizes were fabricated by electro-plating for MEMS devices. The iron content of the deposits was changed by varying the nickel/iron ion ratio in the electrolyte. X-ray diffraction (XRD) analysis was applied for measuring the strength of the texture and grain size of the deposits. The nickel/iron atom ratio of the deposits was analyzed by EDS. The hardness of the alloys was evaluated by Vickers hardness indenter. The internal stress of the deposits was measured by Thin Film Stress Measurement using Stoney's formula. Surface morphology and roughness were investigated by Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). The results of this study revealed that at a grain size of approximately $17\~24$nm the hardness, internal stress and roughness depend strongly on the iron content. With increasing the iron content, the hardness and internal stress of the deposits increased. An excellent correlation between the increase in the internal stress and the loss of (200) texture was found.

• 한국결정성장학회지
• /
• 제27권6호
• /
• pp.303-308
• /
• 2017

여러 가지 금속을 에칭하기 위하여 사용된 $FeCl_3$ 폐용액은 유가금속인 니켈을 함유하고 있다. 본 연구에서는 염화철을 재생하고 남은 니켈 함유 에칭폐액으로부터 니켈을 고순도의 탄산니켈 결정분말로 회수하고자 하였다. 5 % NaOH 수용액을 이용하여 pH 4의 조건에서 1차적으로 철 성분의 불순물을 약 97 % 제거하고 추가적으로 남은 불순물을 제거하기 위하여 용매추출제 D2EHPA(Di-(2-ethylhexyl) phosphoric acid)를 사용하여 불순물로서 존재하는 금속이온들을 약 99% 제거하였다. 그 후 불순물이 제거된 염화니켈 용액에 탄산나트륨과의 반응을 통하여 99.9 % 이상의 순도를 가진 탄산니켈분말을 얻을 수 있었다.

• 마이크로전자및패키징학회지
• /
• 제14권3호
• /
• pp.51-55
• /
• 2007

Ni-Fe 전해도금 시 전류밀도, 펄스주기와 전류인가 방식, 도금욕의 Fe 이온의 농도, 첨가제 등의 인자들이 도금 층의 조성, 표면형상, 표면 경도에 미치는 영향에 관하여 연구하였다. 시편에 가해지는 전류밀도, 전류인가방식과 Fe이온의 농도를 변화시킴으로써 Ni-Fe의 도금 층 내에 Ni-Fe의 조성을 조절하는 것이 가능하였고 또한 첨가제의 양을 변화시킴으로써 표면형상이 변화됨을 확인하였다. PC를 사용한 경우 직류를 사용한 경우보다 높은 $550{\sim}600Hv$의 경도값을 얻을 수 있었다. 사카린을 첨가한 경우 도금층의 잔류응력을 낮추어 균열이 없는 도금층을 얻었다. Ni-Fe의 단면의 조성을 분석함으로써 도금 층의 두께에 따른 조성의 변화를 확인하였다.

• 한국분말재료학회지
• /
• 제17권6호
• /
• pp.489-493
• /
• 2010

Nickel-based and iron-based alloys have been developed and commercialized for a wide range of high performance applications at severely corrosive and high temperature environment. This alloy foam has an outstanding performance which is predestinated for diesel particulate filters, heat exchangers, and catalyst support, noise absorbers, battery, fuel cell, and flame distributers in burners in chemical and automotive industry. Production of alloy foam starts from high-tech coating technology and heat treatment of transient liquid-phase sintering in the high temperature. These technology allow for preparation of a wide variety of foam compositions such as Ni, Cr, Al, Fe on various pore size of pure nickel foam or iron foam in order for tailoring material properties to a specific application.

• 한국표면공학회지
• /
• 제36권6호
• /
• pp.455-460
• /
• 2003

Microstructural and magnetic properties of nanocrystalline Fe-46 wt%Ni and Fe-36 wt%Ni alloys were investigated. Alloys were prepared by the electrodeposition process. The electrolytes were iron sulfate/nickel chloride-based and iron chloride/nickel sulfamate-based solutions. Fe-46 wt%Ni alloy was FCC structure with grain size of 10 nm, but FCC and BCC phases were found in Fe-36 wt%Ni alloy and its grain size was smaller. Effective permeability of Fe-36 wt%Ni alloy was higher than that of Fe-46 wt%Ni alloy in the high frequency range because of large electrical resistivity and small eddy current loss resulted from grain size decrease. Up to $300^{\circ}C$ of annealing temperature, grain growth of Fe-Ni alloys slowly occured. Conversely, annealing above $450^{\circ}C$ led to a drastic grain growth. In that case, effective permeability was decreased at the temperature lower than $300^{\circ}C$ but at $300^{\circ}C$ or higher effective permeability was increased. At the high frequency of 1 MHz, electrodeposited Fe-Ni alloys had higher effective permeability with an decrease in the grain size.

• 한국주조공학회지
• /
• 제3권3호
• /
• pp.174-180
• /
• 1983

The matrix changes and graphite formation in high manganese cast iron (Fe-12Mn-3.5C) are studied with increasing nickel and silicon content. Also, the decomposition of carbides and graphite precipitation are studied by adequate heat treatment.The results obtained in this work are as follows. 1. In high manganese cast iron, fine flakes graphite appeared by adding 5 wt% nickel and A-type flakes graphite can be obtained by adding 7 wt% nickel. 2. Nodular graphite are obtained by graphite spheroidizing treatment with same melt. 3. In high manganese cast iron containing 7 wt% nickel, full austenitic matrix with nodular graphite can be achieved by water quenching after 10 hours' solution heat treatment at $1050^{\circ}C$ in case of containing 2.0 wt% silicon, and 6 hours' at the same temperature in case of containing 2.5 wt% silicon.

• Corrosion Science and Technology
• /
• 제18권1호
• /
• pp.8-15
• /
• 2019

A high-temperature gas-cooled reactor (HTGR) is recognized as the best candidate reactor for next generation nuclear reactors. Helium is used to be the coolant in the core of the HTGR with temperature expected to exceed $900^{\circ}C$ at the core outlet. Several iron- and nickel-based superalloys, including Alloy 800H, Hastelloy X, and Alloy 617, are potential structural materials for intermediate heat exchanger (IHX) in an HTGR. Oxidation behaviors of three selected alloys (Hastelloy X, Alloy 800H, and Alloy 617) were investigated at four different temperatures from $650^{\circ}C$ to $950^{\circ}C$ under helium environments with various concentrations of $O_2$ and $H_2O$. Preliminary results showed that chromium oxide as the primary protective layer was observed on surfaces of the three tested alloys. Based on results of mass gain and SEM analyses, Hastelloy X alloy exhibited the best corrosion resistance in all corrosion tests. Further details on the oxidation mechanism of these alloys are presented in this study.

• Journal of Advanced Marine Engineering and Technology
• /
• 제39권5호
• /
• pp.536-541
• /
• 2015

Copper has been used extensively as an electric wire or as a base material in various types of machineries owing to its good electrical and thermal conductivity and good fabricating property, as well as its good corrosion resistance compared to iron. Furthermore, the copper-nickel alloy has significant corrosion resistance in severely corrosive environments. Although, cupro-nickel alloy shows better corrosion resistance than the brass and bronze series, this alloy also corroded in severely corrosive environments, including aggressive chloride ions, dissolved oxygen, and condition of fast flowing seawater. In this study, and annealing treatment at various annealing temperatures was carried out on the cupro-nickel (Cu-10%Ni) alloy, and the effects of annealing were investigated using electrochemical methods, such as measuring the polarization and impedance behaviors under flowing seawater conditions. The corrosion resistance increased by annealing compared to non heat treatment in the absence of flowing seawater. In particular, the sample annealed at $200^{\circ}C$ exhibited the best corrosion resistance. The impedance in the presence of flowing seawater showed higher values than in the absence of flowing seawater. Furthermore, the highest impedances was observed in the sample annealed at $800^{\circ}C$, irrespective of the present of flowing seawater. Consequently, the corrosion resistance of cupro-nickel (Cu-10%Ni) alloy in a severely corrosive environment can be improved somewhat by annealing.

• Corrosion Science and Technology
• /
• 제7권2호
• /
• pp.92-98
• /
• 2008

This paper describes the experiments of the corrosion and the sliding tests of the nickel-based alloys for the gate valve seating materials used at high pressure and temperature. The general corrosion rates and IGC susceptibility are tested in pressurized water at 533 K and 575 K and in Strauss test solution. The sliding tests have been done in pressurized water at 293 k, 473 K and 573 k. The alloys containing above 10% chromium may have the anti-corrosion properties that could be applied to the valve seats for the power plants. The good sliding performance and the good pressure tightness are obtained when the disc specimens that have hardness 500 to 600 Hv combined with the seat specimens that have hardness 250 to 410 Hv containing about 40 percent of iron. The large size gate valves sliding tests have certified the test results. The anti-wear properties of the seat alloy and the anti-IGC susceptibility of the disc alloy could be improved by the addition of silicon and niobium, respectively.