액체급냉법에 의한 비정질 Ti-Cu-Ni 합금들의 전기화학적 부식특성

김현구,장희진 한국물리학회 2015 새물리 Vol.65 No.9

This study was undertaken to examine the electrochemical corrosion properties of amorphous Ti50Cu30Ni20, Ti70Cu10Ni20, and Ti75Cu15Ni10 alloys prepared with various alloy composition by using the melt-spinning method. The potentiodynamic polarization showed that the corrosion potential (Ecorr) and the corrosion rate (icorr) of the Ti50Cu30Ni20 and Ti70Cu10Ni20 alloys were -0.078 and -0.082 VSCE and about 2.19 × 10−5 and 1.00 × 10−7 A/cm2, respectively, in a pH 2 solution. The corrosion rate of the Ti70Cu10Ni20 alloy was lower than that of the Ti50Cu30Ni20 alloy. This is explained by the fact that the corrosion resistance of the Ti70Cu10Ni20 alloy is primarily dominated by Ti. Also, the Ecorr and the icorr of the Ti70Cu10Ni20 and the Ti75Cu15Ni10 alloys were -0.082 and -0.248 VSCE and about 1.00 × 10−7 and 1.21 × 10−6 A/cm2, respectively. The corrosion resistance of Ti70Cu10Ni20 alloy was better than that of the Ti75Cu15Ni10 alloy. pH가 2인 산성 수용액에서 비정질 Ti50Cu30Ni20, Ti70Cu10Ni20, 그리고 Ti75Cu15Ni10 합금들의 전기화학적 부식 특성을 조사하였다. Ti50Cu30Ni20과 Ti70Cu10Ni20 비정질 합금의 부식전위 (Ecorr)는 각각 약 -0.078 VSCE, -0.082 VSCE로 거의 비슷하게 측정되었으며, 부식속도 (icorr)는 약 2.19 × 10-5 A/cm2과 1.00 × 10-7 A/cm2으로 Ti70Cu10Ni20 합금의 icorr가 Ti50Cu30Ni20 합금의 icorr보다 더 낮게 측정되어 Ni 함량이 일정할 경우 합금의 내식성은 Ti 함량이 높을수록 더 우수할 것으로 생각되었다. 또한 비정질 Ti70Cu10Ni20 합금과 Ti75Cu15Ni10 합금의 Ecorr는 각각 약 -0.082 VSCE와 -0.248 VSCE로 Ti70Cu10Ni20 합금이 더 높게 측정되었으며, icorr는 약 1.00 × 10-7 A/cm2과 1.21 × 10-6 A/cm2 으로 Ti70Cu10Ni20 합금의 icorr가 Ti75Cu15Ni10합금의 icorr보다 더 낮아 부식 저항성이 더 우수할 것으로 생각되었다.

액체급냉법에 의한 비정질 Ti50CuxNi50-x (x = 30, 20 at.%) 합금들의 전기화학적 부식 특성

김현구,장희진 한국물리학회 2014 새물리 Vol.64 No.6

수용액의 pH에 따른 비정질 Ti50Cu30N20, Ti50Cu20Ni30 합금들 (at.%)의 전기화학적 부식 특성을 조사하였다. pH가 2 또는 7인 용액에서 부식전위는 Cu 함량이 상대적으로 높은 Ti50Cu30Ni20 합금의 부식전위가 Ti50Cu20Ni30 합금보다 조금 더 높았고 pH 2인 용액에서 pH 7인 용액에서보다 높았다. 부식속도 또한 Ti50Cu30Ni20 합금의 부식속도가 Ti50Cu20Ni30 합금의 부식속도보다 조금 더 낮았고, pH 7에서의 부식속도가 pH 2에 비해 대체적으로 낮았다. 따라서 Ti 함량이 일정할 경우 합금의 내식성은 Cu의 함량이 높을수록 우수하며, 그 효과는 산성보다는 중성의 수용액에서 더 큰 것으로 생각된다. This study was undertaken to examine the electrochemical corrosion properties of amorphous Ti50Cu30N20 and Ti50Cu20Ni30 alloys prepared by using the melt-spinning method under various alloy compositions and value of the solution's pH. The potentiodynamic polarization showed that the corrosion potential of the Ti50Cu30Ni20 alloy was higher than that of the Ti50Cu20Ni30 alloyin both pH-2 and pH-7 buffer solutions while the corrosion rate of the Ti50Cu30Ni20 alloy was lower than that of the Ti50Cu20Ni30 alloy. This is explained by the fact that Cu has a lower dissolution rate than Ni does at the corrosion potential of the alloys.

액체급냉법에 의한 비정질 Fe-Nb-B 합금의 전기화학적 부식특성

김은선,김현구,장희진 한국물리학회 2014 새물리 Vol.64 No.8

This study was undertaken to examine the electrochemical corrosion properties of Fe-Nb-B amorphous alloys prepared by using the melt-spinning method under various conditions. The potentiodynamic polarization responses at various levels of pH (pH 2, pH 7, pH 12) showed that the uniform corrosion resistance of the Fe80Nb10B10 alloy was better than that of the Fe82Nb8}B10 alloy at all levels of pH. The corrosion rate of an alloy is usually reduced by increasing the solution's pH. The Fe82Nb8B10} alloy was passivated neither in a 0.01 M nor a 0.1 M NaCl solution. Pitting occurred on Fe80Nb0B10, and the pitting potential was lower at hi 상온에서 pH 값과 NaCl 수용액 농도에 따른 분극실험을 하여 비정질 합금 Fe-Nb-B의 전기화학적 부식특성을 조사하였다. pH 2, pH 7, pH 12 완충용액에서 모든 시료들이 부동태 거동을 하였으며, Fe 함량이 낮고 Nb 함량이 높을수록 내식성이 우수하게 나타났다. Fe80Nb10B10 합금은 pH가 높아질수록 부식전류(imathrm{corr}} 값이 낮아지나, Fe82Nb8B10 합금은 산성도에 따른 변화가 거의 없는 것으로 나타났다. 0.01 M과 0.1 M NaCl 수용액에서는 Fe82Nb8B10 합금이 부동태화 되지 않은 반면, Fe80Nb{10}B10 합금의 경우에 부동태 구간이 나타난 것으로 미루어 볼 때 NaCl 수용액에서 Fe 함량이 낮고 Nb 함량이 높은 경우에 공식저항성이 높은 것으로 판단된다.

Ni-based 비정질 합금막의 수소투과 특성

석송,이덕영,김윤배 한국수소및신에너지학회 2008 한국수소 및 신에너지학회논문집 Vol.19 No.1

Ni-based amorphous alloy ribbon was prepared by a single-roller melt-spinning technique. Palladium coating was found to enhance significantly the absorption/desorption behavior of hydrogen in amorphous alloy. The hydrogen permeability of a Pd-coated (Ni60Nb40)100-XTaX(x=5, 10) amorphous alloy was examined in the temperature range of 623~773 K, comparable with those of Pd60-Cu40 alloys. The permeated hydrogen flux was increased with increasing the temperature and the difference of hydrogen pressure between the feed side and permeates side of the membrane. The Ni-based amorphous alloys were characterized by X-ray diffractometry(XRD) and differential scanning calorimetry(DSC). The morphology of surface and roughness was observed by using scanning electron microscopy(SEM) and atomic force microscopy(AFM).

비정질 합금의 마이크로 패턴 레이저 가공

김한,박종욱 한국기계가공학회 2022 한국기계가공학회지 Vol.21 No.4

Amorphous alloys exhibit excellent mechanical properties; therefore, application technology development isbeing attempted in various fields. However, industrial use of application technology is limited owing to thelimitations in fabrication. In this study, micropattern fabrication of an amorphous alloy was conducted using laserbeam machining. Although microhole fabrication is possible without the deformation of the amorphous phasethrough nanosecond pulsed laser beam machining, there are limitations in the generation of recast layers andspatters. In cover plate laser beam machining (c-LBM), a cover plate is used to reduce the thermal deformationand processing area. Therefore, it is possible to fabricate holes at the level of several micrometers. In this study,it was confirmed that recast layers are hardly generated in c-LBM. Furthermore, square-shaped micropatternswere successfully fabricated using c-LBM.

비정질 Zr65Al8Ni5Cu 금속합금의 전기화학적 부식 특성

김현구 한국물리학회 2010 새물리 Vol.60 No.3

This study was undertaken to measure the electrochemical corrosion of an amorphous Zr65Al8Ni5Cu22 (at.%) alloy ribbon under various conditions, including 70-mM H₂SO₄, 0.4-mM HCl solutions, various values of the pH, and various immersion times. The HCl solution produced more corrosion than the H₂SO₄solution, and the highest value of Icorr was measured in the H₂SO₄solution at 45℃. The Rp was inversely proportional to the corrosion rate, increasing with increasing temperature. While pH=9 was not as sensitive as other pH, pH=5 was more sensitive than other pH for amorphous Zr65Al8Ni5Cu22 (at.%) alloy. The change in the mass of the H₂SO₄solution with immersion time after 200 h was greater than for the HCl solution. 주어진 온도에서의 황산과 염산수용액, pH, 그리고 담금시간 등에 따른 비정질합금 Zr65Al8Ni5Cu22의 전기화학적 부식특성 실험을 하였다. 비정질 Zr65Al8Ni5Cu22 시료는 황산수용액에 비해 염산수용액에서 대체적으로 부식에 더욱 민감함을 알 수 있었고, 45℃의 황산수용액에서 가장 큰 부식전류밀도(Icorr)가 측정되었다. pH=9에서는 다른 pH값들에 비해 부식에 대한 반응이 더 느리게 나타나는 반면, pH=5에서는 시료에 대한 부식 반응이 상당히 빨랐다. 담금 시간이 200시간까지는 황산과 염산수용액에서 질량변화는 없었으나, 담근 시간이 200시간 이후에는 염산수용액보다 황산수용액에서 더 큰 질량 변화를 볼 수 있었다.

CoFeZr 합금박막의 미세구조, 자기적 특성 및 비정질 CoFeZr 합금박막을 사용한 스핀밸브의 자기저항 특성에 관한 연구

안황기(Whang-gi Ahn),박대원(Daewon Park),김기수(Kisu Kim),이성래(Seong-Rae Lee) 한국자기학회 2008 韓國磁氣學會誌 Vol.18 No.6

Magnetic and structural properties of CoFeZr alloy films as a function of Zr concentration and magnetoresistive properties of spin valves incorporated with amorphous CoFeZr alloy films have been studied. Magnetization and coercivity of CoFeZr alloy films decreased as the Zr content increased. A single amorphous CoFeZr phase was formed when the Zr content is about above 18 at%. Magnetoresistance ratio and exchange coupling field of spin valves with amorphous CoFeZr were reduced slightly as compared with spin valves with CoFe because the resistance of amophous CoFeZr is higher than that of crystalline CoFe. However, the Δρ of spin valves with amorphous CoFeZr was improved due to reduction of current shunting.

알루미늄기 비정질 와이어의 제조와 그 특성연구

김영환 釜山大學校生産技術硏究所 1999 生産技術硏究所論文集 Vol.56 No.-

높은 반응성을 가지는 Al-Ni-Y(또는 Ce)합금을 60°각도의 날카로운 edge를 가지는 구리휠을 사용하여 용탕추출법(melt extration)에 의해 연속적인 비정질 와이어를 제조할 수 있었다. 와이어는 원형 단면을 가지고 지름이 35∼50㎛범위였다. 와이어의 열적 성질은 멜트스피닝법으로 제조딘 두께 15㎛인 리본재와 거의 같앗다. 그리고 연성도 우수하고 1020MPa의 커다란 인장강도가 비정질 Al86Nil0Y4합금와이어에서 얻어졌다. 리본재에 비해서 본 제조기술이 높으 응고속도를 가지는 것이 밝혀졌는데, 이것은 체적에 비해서 훨씬 큰 표면적을 가짐으로써 아르곤 가스 분위기하에서 쉽게 과냉이 되기 때문이라고 생각된다. The application of a melt extraction method using a copper wheel with a steep edge to Al-Ni-Y(or Ce) alloys with highly reactive molten states was found to cause the formation of continuous amorphous wire. The wires have circular cross section and the diameters are in the range of 35 to 50㎛. The thermal property of the wire is nearly the same as that of the melt-spun ribbon with the 15㎛ thick. and same composition. The wires have good bending ductility and a tensile strength of 1020 MPa. The high cooling rate for the present pocess is accomplished presumably because the supercooled liquid with a small volume and a large outer area to volume ratio is solidified homogeneously without contact of other substances. The combination of the solidification process with high cooling rate and the good bending ductility into the wire shape allows us to expect that the present process develops as an alternative method to produce amorphous ally wires in various kinds of alloy systems including reactive elements as main components.

(Ni60-Nb40)95-Pd5 비정질 금속막의 수소투과 특성

이덕영,김윤배 한국수소및신에너지학회 2008 한국수소 및 신에너지학회논문집 Vol.19 No.4

Hydrogen as a high-quality and clean energy carrier has attracted renewed and ever-increasing attention around the world in recent years, mainly due to developments in fuel cells and environmental pressures including climate change issues. In this processes for hydrogen production from fossil fuels, separation and purification is a critical technology. (Ni60-Nb40)95-Pd5 alloy ingots were prepared by arc-melting the mixture of pure metals in an Ar atmosphere. Melt-spun ribbons were produced by the single-roller melt-spinning technique in an Ar atmosphere. Amorphous structure and thermal behavior were characterized by XRD and DSC. The permeability of the (Ni60-Nb40)95-Pd5 amorphous alloy membrane was characterized by hydrogen permeation experiments in the temperature range 623 to 773 K and pressure of 2 bars. The maximum hydrogen permeability was 3.54☓10-9[mol․m-1 s-1․pa-1/2] at 773 K for the (Ni60-Nb40)95-Pd5 amorphous alloy.

철기(Fe Based) 나노결정질 합금 분말코어의 코팅제 및 입도가 연자기적 특성에 미치는 영향

장세종(S. J. Jang),최영진(Y. J. Choi),김상욱(S. W. Kim),전병서(B. S. Jeon),이태행(T. H. Lee),송창빈(C. B. Song),남궁정(J. Namkung) 한국자기학회 2015 韓國磁氣學會誌 Vol.25 No.3

This is a basic research for improving soft magnetic property of Fe based nano crystalline alloy powder core. The main study is done around characteristics of permeability, core loss, and DC bias depending on amount of insulation coating agent and particle size. First, Fe<SUB>73.5</SUB>Si<SUB>13.5</SUB>B<SUB>9</SUB>Nb₃Cu₁ amorphous alloy ribbon was fabricated by using the planar flow casting (PFC) device. Then, heat treatment and ball milling were done to obtain alloy powder. The amount of polyether imide (PEI) added to it was varied by 0.5, 1.0, 2.0, 2.5 wt% to have compression molding into 16 ton/㎠. After going through crystalline heat treatment, the made toroidal nano crystalline powder core (OD12.7 mm*ID7.62 mm*H4.75 mm) had smaller permeability as amount of insulation coating agent decreases. However, it was found out that core loss and DC bias characteristics have been improved. The reason for this results were expected to be because green density of power core decreases as amorphous alloy powder particles become smaller as amount of alloy powder insulation coating agent increases, it was determined that 1 wt% of insulation coating agent is appropriate. Also, for powder core made based on alloy powder size with amount of insulation coating agent fixed at 1 wt%, effective permeability and core loss were outstanding as particle size became bigger. However, characteristics of DC bias became worse as applied DC field increases. This is expected to be due to insulation effect, residual pores, or molding density of powder core resulting from thickness of coating on surface of alloy powder.