• 한국전기전자재료학회논문지
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• 제18권8호
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• pp.714-719
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• 2005

NiCr thin film was deposited by DC magnetron sputtering on $A;_2O_3$/Si substrate with NiCr (80:20) alloy target. NiCr thin films were annealed at $300^{\circ}C,\;400^{\circ}C,\;500^{\circ}C,\;600^{\circ}C,\;and\;700^{\circ}C$ for 6 hr in $H_2$ after annealing at $500^{\circ}C$ for 6hr in air atmosphere, respectively. To analyze NiCr thin film properties, the changes of its micro structure were Investigated through field emission scanning electron microscope (FESEM). X-ray photoelectron spectroscopy (XPS) was used to analyze a surface of NiCr thin film. Resistance of NiCr thin film was measured by 4-point probe technique. The generated heats were measured by infrared thermometer through the application of DC voltage (5 V/l2 V). NiCr thin film treated by gradational double annealing process had uniform and small grains. Maximum temperature generated heat by NiCr micro heater was $173^{\circ}C$. We expect that our results will be a useful reference in the realization of NiCr micro heater.

• Progress in Superconductivity
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• 제1권2호
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• pp.120-124
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• 2000

Ni-13%Cr and Ni-70%Cu alloy tapes were prepared by using high purity metal powders as starting materials. The Ni-13%Cr and the Ni-70%Cu mixtures were isostatically pressed, sintered, rolled and texture-annealed. SEM EDS analysis showed that copper and nickel atoms were completely mixed, while the alloying between the chromium powders and the nickel powders was incomplete. In spite of incomplete alloying between nickel and chromium powders, sharp cube-texture was developed for the Ni-13%Cr tape as well as the Ni-70%Cu tape.

• 한국분말재료학회지
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• 제18권5호
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• pp.456-462
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• 2011

Yttrium oxide is one of the most thermo-dynamically stable materials, so that it is generally used as a dispersoid in many kinds of dispersion strengthed alloys. In this study, a nickel-base superalloy is strengthened by dispersion of yttrium oxide particles. Elemental powders with the composition of Ni-22Cr-18Fe-9Mo were mechanically alloyed(M.A.) with 0.6 wt% $Y_2O_3$. The MA powders were then HIP(hot isotactic press)ed and hot rolled. Most oxide particles in Ni-22Cr-18Fe-9Mo base ODS alloy were found to be Y-Ti-O type. The oxide particles were uniformly dispersed in the matrix and also on the grain boundaries. Tensile test results show that the yield strength and ultimate tensile strength of ODS alloy specimens were 1.2~1.7 times higher than those of the conventional $Hastelloy^{TM}$ X(R), which has the same chemical compositions with ODS alloy specimens except the oxide particles.

• Corrosion Science and Technology
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• 제13권5호
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• pp.178-185
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• 2014

Alloy 617 is considered as a candidate Ni-based superalloy for the intermediate heat exchanger (IHX) of a very high-temperature gas reactor (VHTR) because of its good creep strength and corrosion resistance at high temperatures. Helium is used as a coolant in a VHTR owing to its high thermal conductivity, inertness, and low neutron absorption. However, helium inevitably includes impurities that create an imbalance in the surface reactivity at the interface of the coolant and the exposed materials. As the Alloy 617 has been exposed to high temperatures at $950^{\circ}C$ in the impure helium environment of a VHTR, the degradation of material is accelerated and mechanical properties decreased. The high-temperature strength, creep, and corrosion properties of the structural material for an IHX are highly important to maintain the integrity in a harsh environment for a 60 year period. Therefore, an alloy superior to alloy 617 should be developed. In this study, the mechanical and high-temperature corrosion properties for Ni-Cr alloys fabricated in the laboratory were evaluated as a function of the grain boundary strengthening and alloying elements. The ductility increased and decreased by increasing the amount of Mo and Cr, respectively. Surface oxide was detached during the corrosion test, when Al was not added to alloy. However the alloy with Al showed improved oxide adhesive property without significant degradation and mechanical property. Aluminum seems to act as an anti-corrosive role in the Ni-based alloy.

• 한국산학기술학회논문지
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• 제18권9호
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• pp.244-250
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• 2017

보철물의 완성도를 평가할 수 있는 요소는 여러 가지가 있으나, 그 중 가장 중요한 하나는 보철물의 적합도이다. 합금은 기계적, 물리적 성질 그리고 연마성 개선을 위해 연화열처리나 경화열처리 과정을 거치는데, 이때의 열처리 방법이 Ni-Cr 합금 core의 변연 및 내면 간격에 어떠한 영향을 미치는지 알아보고자 한다. 실험을 위해 하악 좌측 대구치가 지대치인 석고 모형 30개를 제작하고 dipping법을 이용하여, 3 group(A, B, C)으로 나누어 group당 10개, 총 30개의 Ni-Cr 합금 core를 제작 하였다. 이들을 열처리를 하지 않은 것과 연화, 경화 열처리 방법으로 열처리함에 따라 적합도를 silicone replica technique을 이용하여 측정하였다. 세 집단 간의 평균값에 유의한 차이가 있는지 알아보기 해 독립표본 t-검정으로 분석하였다(${\alpha}=0.05$). 실험 결과 변연 부위(1, 6)에서는 통계적으로 유의한 차이를 보였으나(p<0.05), 나머지 내면 부위(2, 3, 4, 5)에서는 유의한 차이를 보이지 않았다(p>0.05). 이러한 결과로 미루어 볼 때 Ni-Cr 합금은 열처리를 하지 않는 것이 적합도 측면에서 나을 것으로 사료된다. 이에 추가적인 임상적용 연구를 통해 더욱 심도 있는 평가되어야 할 것으로 판단된다.

• 한국재료학회지
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• 제13권10호
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• pp.640-644
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• 2003

NiCr thin films were fabricated by rf magnetron sputtering for applying to both the top electrode and absorption layer on Pb(Zr, Ti)O$_3$(PZT) thin films for infrared sensors. The rms roughness and resistivity of NiCr films prepared with Ni power of 80 W and Cr power of 50 W showed the most stable oxidation resistance after annealing at $600^{\circ}C$ for 5 min in oxygen ambient. The rms roughness and resistivity of NiCr films annealed at $V^{\circ}C$ in oxygen ambient were about 2$0\AA$ and $70 \mu$Ω-cm, respectively. As-deposited Ni/PZT/Pt and NiCr (Ni 80 W, Cr 50 W)/PZT/Pt structures showed well saturated hysteresis loops. However, in case of the samples annealed at $500^{\circ}C$ in oxygen ambient, only NiCr/PZT/Pt showed saturated loops having a remanent polarization of 20$\mu$C/$\textrm{cm}^2$. Ultra-thin NiCr films showed a possibility as a top electrode for infrared sensors.

• 대한치과보철학회지
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• 제41권2호
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• pp.207-222
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• 2003

As a material of metal-ceramic prosthesis, nickel as a form of Ni-Cr alloy has been used for many dental prostheses in many cases. However, several problems in use of the alloy have been revealed (ex ; tissue stimulation, skin allergy, hypersensitivity cytotoxicity and carcinogenecity). Little is known about nickel with respect to the relationship between Ni-prosthesis and gaining of Niresistance in oral microorganisms. The present study was undertaken to check whether use of Ni-prosthesis leads to occurrence of Ni-resistant microorganisms. So this study may suggest the possible relationships between the oral microorganisms and nickel-resistance in oral environment. Bacteria were isolated from the gingival crevicular fluid on the patients wearing Ni-Cr prosthesis. The isolated bacteria were tested fir their Ni-resistance in nickel containing media at different concentration from 3mM to 110mM. E. coli HB101 was used as control. The Ni-resistant bacteria were isolated and biochemically identified. The Ni-resistant bacteria were tested several biochemical, molecular-biological tests. Performed tests were : measuring the growth curve, antibiotic test, growth ability test in liquid media, isolation of the chromosome and plasmid, digestion of DNA by restriction enzyme, electrophoresis of chromosome and plasmid DNA, identification of Ni-resistant genes by the DNA hybridization. The results were as follows 1) The bacteria isolated from gingival crevicular fluid on the patients wearing Ni-Cr alloy prosthesis showed nickel-resistance. 2) The isolated microorganisms grew at nickel containing media of high concentrations (60mM-110mM). 3) Based on the biochemical tests, the isolated microorganisms were identified as Enterococcus faecalis(13 cases), Klebsiella pneumoniae(1 case) and Enterobacter gergoviae(1 case). 4) Enterococcus faecalis expressed not only nickel resistance but also the multi-drug resistance to several antibiotics ; chloramphenicol, kanamicin, streptomycin, lincomycin, clindamycin, However, all strain showed the sensitivity against the tetracycline. 5) DNA hybridization result suggests that there is no homology between the previously known gene of nickel resistance in Klebsiella pneumoniae and chromosomal DNA of Enterococcus faecalis.

• 대한치과기공학회지
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• 제17권1호
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• pp.5-9
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• 1995

This study was carried out by obsorving to the conditions of an oxide on the surface of alloy according to the conditions of its heat treatment and analysing the change in composition on its surface. The result of this study is summarized as fellows. 1. It was shown that the higher the more the generated metal oxide while the higher the temperature of heat treatment. 2. The metal oxide was manily composed of Ni and Cr oxides. 3. The Ni composition indicated reduction while the higher the heat treatment in vaccum condition. 4. The Cr composition indicated increase while the higher the heat treatment in vaccum condition.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1995년도 추계학술발표회논문집(2)
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• pp.723-728
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• 1995

Alloy 600 표면에 레이저 빔을 이용하여 Ni, Cr 흔합분말 및 순수 Cr 분말로 표면합금층을 만들었다. 표면 합금층은 모재와 정합계면를 이루고 있으며 레이저 표면용용 시편에서와 같이 크게 면선단 응고부와 셀룰라 응고부로 나눌 수 있고, 모재에는 레이저 처리과정에서 생긴 수십 $\mu\textrm{m}$ 두께의 열영향 부위가 존재하였다. 그리고 합금층 내부에는 레이저 표면 용용된 시편과 달리 구형의 커다란 기공(pores)이 존재하였다. 레이저 표면 합금층에서 합금원소의 조성 분포를 조사하기 위해 레이저 처리된 시편에 대해 WDX 분석을 하였고, 합금층 내부에 Ni, Cr, Fe 원소의 조성 분포는 매우 균일하였다.

• 한국자기학회지
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• 제3권4호
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• pp.277-283
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• 1993

세개의 오스테 나이트계의 Fe-Cr-Ni 스테인레스 합금강들의 DC 자화율의 온도의존성을 4.2-300 K 온도영역에서 측정하였다. 측정결과 두개의 합금강들은 two-magnetic-phase 모델(spin glass와 초상자성)을 만족하였으며 나머지 하나는 자기적 2중 천이현상을 나타내었다. 또한 Ni/Cr의 비가 증가할수록 자화율의 최 대값이 증가하고 이 값을 나타내는 온도는 감소하였다.