백색 5K Au-Ag-In 합금재의 인듐 첨가량에 따른 물성 변화

송정호,송오성,Song, Jeongho,Song, Ohsung 한국재료학회 2017 한국재료학회지 Vol.27 No.7

In order to replace 14K white gold alloys, the properties of 5K white gold alloys (Au20-Ag80) were investigated by changing the contents of In (0.0-10.0 wt%). Energy dispersive X-ray spectroscopy (EDS) was used to determine the precise content of alloys. Properties of the alloys such as hardness, melting point, color difference, and corrosion resistance were determined using Vickers Hardness test, TGA-DTA, UV-VIS-NIR-colorimetry, and salt-spray tests, respectively. Wetting angle analysis was performed to determine the wettability of the alloys on plaster. The results of the EDS analysis confirmed that the Au-Ag-In alloys had been fabricated with the intended composition. The results of the Vickers hardness test revealed that each Au-Ag-In alloy had higher mechanical hardness than that of 14K white gold. TGA-DTA analysis showed that the melting point decreased with an increase in the In content. In particular, the alloy containing 10.0 wt% In showed a lower melting temperature (> $70^{\circ}C$) than the other alloys, which implied that alloys containing 10.0 wt% In can be used as soldering materials for Au-Ag-In alloys. Color difference analysis also revealed that all the Au-Ag-In alloys showed a color difference of less than 6.51 with respect to 14K white gold, which implied a white metallic color. A 72-h salt-spray test confirmed that the Au-AgIn alloys showed better corrosion resistance than 14K white gold alloys. All Au-Ag-In alloys showed wetting angle similar to that of 14K white gold alloys. It was observed that the 10.0 wt% In alloy had a very small wetting angle, further confirming it as a good soldering material for white metals. Our results show that white 5K Au-Ag-In alloys with appropriate properties might be successful substitutes for 14K white gold alloys.

임시 금관용 비귀금속 합금의 전기화학적 부식에 관한 연구

김정욱,임범순,김철위 서울대학교 치과대학 치과생체재료학교실 1994 치과생체재료학 논문집 Vol.2 No.1

The employment of base metal alloys as substitutes of gold alloys is gaining increasing popularity. The corrosion of dental base metal alloys was recoginzed due to the nature of the oral environment. Corrosion of dental meterials in the mouth can affect the mechanical properties, esthetic properties and efficiency of dental metallic restorations, and has great influence upon the local and systemic health of the patient. The researches on the harmful effect of dental base metal alloys and their corrosin products on the human body are progressed actively. The electrochemical corrosion studies in vitro were done to predict the corrosion behavior of dental alloys in vivo, but the result may be different depending on the corrosion environments. As the normal range of inorganic ions and organic molecules in saliva is various with patient, in vivo corrosion behavior may be different depending on the patients. It may result in interindividual differences on corrosion behavior even though the restorations were made of the same alloy. The purpose of this experiment was to evaluate the difference in corrosion behavior of dental base metal alloys for temporay crown when the concentrations of organic compounds in the artificial saliva were varied. The materials used in this study were the modified Fusayma's artificial saliva (pH. 6.7), and the artificial saliva with organic compound additions such as polyacrylic (5㎖/1), acetic (5㎖/1), citric (2 g/l) and lactic acid (5㎖/1). Totalof four kinds of dental base metal alloys for temporary crown; two kinds of stainless stel alloys (SSP: 17% Cr-12% Ni-67% Fe, INC : 17% Cr-9% Ni-68% Fe), nickel-chromium alloys (APC : 90% Ni-5.5% Ni-4.5% Cu), and aluminium alloys (APC : 99% Al-0.5% Fe-0.1% Cu), were studied. Specimens were 0.2㎜ thick and had surface area of 1 ㎠ (or 0.25㎠). The specimens were connected to the copper wire and mounted in the self-curing acrylic resin. Embedded specimens were polished with the silicon caarbide papers up to # 2,000, then ultrasonically cleaned, and dried by clean air. After the surface oxide layer of specimens was removed at-1,500㎷(SCE) immersed in the vairous meterials, the corrosion behaviors of the specimens were studied by electrochemical hysteresis technique involving potentiodynamic polarization from - 1,000 ㎷ to + 1,000 ㎷ and reverse polarization back to -1,000 ㎷ with the scanning rate of 2㎷/sec in the aeration environment. The current density change of specimen was recorded X-Y poltter via logarithmic onverter. From the experiment, the following results werre obtained : 1. For the stainless steel specimen SSP, passivation film was formed in the artificial saliva and in the artificial saliva with organic components added electrolytes. SSp showed the good corrosion resistance in experimental electrolytes. Addition of organic components to the artificial saliva showed only minor effect. 2. The formation of passivation film on INC was unstable. It was observed that the corrosion resistance on INC was lower than that of SSP. 3. In the nickel-chromium alloys specimen APC, the possibility of passivation film formation was lower than in the stainless steel specimens SSP and INC. It causes lower corrosion resistance than that of SSP and INC. 4. In the aluminium alloys specimen, ATP, showed the dissolution reaction in all experimental electrolyes such as artificial saliva and artificial saliva with polyacrylic, acetic, citric, and lactic acid added.

Icosahedral 상을 갖는 Mg-8Zn-1.6Y 합금의 크리프 거동에 미치는 Ca 첨가 영향

정영길,양원석,김세광,임현규,오건영,김영균,김도향 한국주조공학회 2020 한국주조공학회지 Vol.40 No.2

The high-temperature stability of Mg-8.0Zn-1.6Y (wt.%) alloys upon the addition of Ca has been investigated by characterizing the ignition temperature, microstructure, tensile and creep properties. The ignition temperature increases with an increase in the Ca content, indicating that an addition of Ca enhances the ignition resistance of the Mg-Zn-Y alloy. The as-cast microstructures of all tested alloys mainly consisted of the dendritic -Mg matrix and I-phase (Mg3Zn6Y) at the grain boundaries. In the Ca-added Mg8.0Zn-1.6Y alloys, the Ca2Mg6Zn3 phase forms, with this phase fraction increasing with an increase in the Ca contents. However, a high volume fraction of the Ca2Mg6Zn3 phase rather deteriorates the mechanical properties. Therefore, a moderate amount of Ca element in Mg-8.0Zn-1.6Y alloys is effective for improving the tensile and creep properties of the Mg-Zn-Y alloy. The Mg-8.0Zn1.6Y-0.3Ca alloy exhibits the highest tensile strength and the lowest creep strain among the alloys investigated in the present study. The creep resistance of Mg-Zn-Y-Ca alloys depends on the selection of the secondary solidification phase; i.e., when Ca2Mg6Zn3 forms in an alloy containing a high level of Ca, the creep resistance deteriorates because Ca2Mg6Zn3 is less stable than the I-phase at a high temperature The high-temperature stability of Mg-8.0Zn-1.6Y (wt.%) alloys upon the addition of Ca has been investigated by characterizing the ignition temperature, microstructure, tensile and creep properties. The ignition temperature increases with an increase in the Ca content, indicating that an addition of Ca enhances the ignition resistance of the Mg-Zn-Y alloy. The as-cast microstructures of all tested alloys mainly consisted of the dendritic -Mg matrix and I-phase (Mg3Zn6Y) at the grain boundaries. In the Ca-added Mg8.0Zn-1.6Y alloys, the Ca2Mg6Zn3 phase forms, with this phase fraction increasing with an increase in the Ca contents. However, a high volume fraction of the Ca2Mg6Zn3 phase rather deteriorates the mechanical properties. Therefore, a moderate amount of Ca element in Mg-8.0Zn-1.6Y alloys is effective for improving the tensile and creep properties of the Mg-Zn-Y alloy. The Mg-8.0Zn1.6Y-0.3Ca alloy exhibits the highest tensile strength and the lowest creep strain among the alloys investigated in the present study. The creep resistance of Mg-Zn-Y-Ca alloys depends on the selection of the secondary solidification phase; i.e., when Ca2Mg6Zn3 forms in an alloy containing a high level of Ca, the creep resistance deteriorates because Ca2Mg6Zn3 is less stable than the I-phase at a high temperature.

인공타액에서 염소이온과 황이온 농도가 치과용 귀금속계 합금의 변색 및 부식저항에 주는 영향 : 1. 시판 치과용 귀금속계 합금 1. DENTAL COMMERCIAL NOBLE METAL BASED ALLOYS

임범순,문현정,김철위 대한치과기재학회 1998 대한치과재료학회지 Vol.25 No.2

The object of this study was to study effect of Cl- and S²- ions on tarnish and corrosion resistance of dental noble metal alloys in the artificial saliva. Twenty-four commercial dental noble metal based alloys(five for high-Au based alloys, seven for low-Au based alloys, four for Pd-based alloys, and eight for Ag-Pd based alloys) were investigated by the Potentiostat and the Spectrophotometer. Modified Fusayama's artificial salivas with various concentrations of Cl- ion(1.22, 12.22, 24.44, and 61.10 mM/ℓ) and S²- ions(0.01, 0.10, 0.20, 0.35, 0.50, 1.00, 5.00, 10.0, and 20.0 mM/ℓ) were used as electrolytes for test. From the experiments, the following results were obtained. Concentration of Cl- ion in artificial saliva did not in fluence the potentiodynamic polarization curves for dental noble metal alloys. On the other hand, concentration of S²- ion in artificial saliva strongly influenced the potentiodynamic polarization curves for dental noble metal alloys ; corrosion potentials were decreased up to 500 mV and current densities were increased by 100 times. In color change measurements after potentiodynamic polarization curve test, the values of ΔE for high-Ae and Pd-based alloys were increased as the concentration of S²- increased up to 1.00 mM and then were reached a plateau at higher concentration of S²-. For low-Au and Ag-Pd based alloys, the values of ΔE were drastically decreased as the concentration of S²- increased up to 1.00 mM and then were reached a plateau at higher concentration of S²-. By determining the color of an alloy before and after exposure to a test solution, the color changes were ranged of 4∼6 for high-Au and Pd-based alloys and 20∼35 for low-Au and Ag-Pd based alloys.

Ti-Cr-Mo계 및 Ti-Cr-V계 bcc 합금의 수소저장특성에 관한 연구

유정현,조성욱,박충년,최전 한국수소및신에너지학회 2005 한국수소 및 신에너지학회논문집 Vol.16 No.2

The characteristics of hydrogen storage have been investigated in the Ti-Cr-Mo and Ti-Cr-V ternary alloys with bcc structure. The alloys were melted by arc furnace and remelted 4-5 times for homogeneity. The lattice parameters, microstructures and phases of the alloys were examined by SEM, EDX and XRD, and the Pressure-Composition isotherms of the alloys were measured. From these data the relationship of the maximum and effective hydrogen storage capacities vs. chemical composition, lattice parameter and the radius of tetrahedral site were analyzed and discussed.The results showed that all of these alloy, in the range of the this study, had mainly bcc solid solutions with small amount of Ti segregation due to a lower melting point of Ti compared with other elements. Lattice parameters of the alloys were very near to the atomic average values of lattice parameters of the constituent elements. It was also found that maximum hydrogen storage capacities of the Ti-Cr-Mo alloys increased with increasing Ti content and the radius of tetrahedral site but the effective hydrogen storage capacities decreased after showing the maximum. The hydrogen storage capacities of the Ti-Cr-V alloys were almost same even though the V contens were quite different from alloy to alloy and this could be attributed to the almost same Ti/Cr ratio of the alloys. The maximum effective hydrogen storage capacity of the Ti-Cr-Mo alloys was revealed at Ti content of about 40∼50 at% and radius of tetrahedral site of 0.43∼0.45 nm. The Ti-Cr-V alloys showed the hydrogen storage capacities of 3.0 wt% and effective hydrogen storage capacities of 1.5 wt%.

Corrosion studies of high pressure die-cast Al-Si-Ni and Al-Si-Ni-Cu alloys

Arthanari, Srinivasan,Jang, Jae Cheol,Shin, Kwang Seon Elsevier 2018 Journal of alloys and compounds Vol.749 No.-

<P><B>Abstract</B></P> <P>Corrosion behavior of high pressure die-cast Al-Si-Ni alloys (Al-3Si-1Ni (SN31) and Al-3Si-3Ni (SN33)) with and without copper (Cu) addition has been investigated. Corrosion behavior was assessed in 3.5 wt% NaCl by electrochemical and immersion corrosion techniques. The presence of single phase pure Si and binary Al<SUB>3</SUB>Ni phases were confirmed from the X-ray diffraction (XRD) and microstructural studies for SN31 and SN33 alloys. Interestingly, Cu addition (1 at.%) resulted in formation of Al<SUB>3</SUB>Ni<SUB>2</SUB> phase along with a marginal decrease in Al<SUB>3</SUB>Ni fraction and did not produce any Cu containing phases. Potententiodynamic polarization studies revealed an increase in corrosion current density (i<SUB>corr</SUB>) value as the Ni content was increased. However, the addition of Cu to SN31 and SN33 alloys increased their corrosion resistance. Electrochemical impedance spectroscopy studies confirmed the higher charge transfer resistance (R<SUB>ct</SUB>) values for the Cu added alloys. Immersion corrosion test results revealed that, the corrosion rate of Cu added alloys were three times lower than SN31 and SN33 alloys. In the SN alloys, increase in corrosion rate is attributed to the increase of Al<SUB>3</SUB>Ni phase as the Ni content was increased. The added Cu dissolves in the Al alloys and also reduce the Al<SUB>3</SUB>Ni fraction thereby improved their corrosion resistance.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Al-Si alloys with Ni and Cu were developed by high pressure die-casting. </LI> <LI> Influence of Ni and Cu addition on the corrosion behavior was investigated. </LI> <LI> Corrosion resistance was assessed by electrochemical and immersion tests. </LI> <LI> Increase in Ni content decreased the corrosion resistance of the Al-Si alloy. </LI> <LI> Addition of Cu improved the corrosion resistance of Al-Si-Ni alloys. </LI> </UL> </P>

치과용 합금의 부식 특성에 관한 연구

오근택,김명화,최병갑,김경남 大韓齒科器材學會 2002 대한치과재료학회지 Vol.29 No.1

For the aesthetic and functional restoration of edentulous patients, recently dental implants have been used widely. Dental implants and restorative alloys are required with the high corrosion resistance. Therefore, Ti and its alloys have been used as implant materials and gold, silver, Ni-Cr and Co-Cr alloys and dental restorative materials due to their high corrosion resistance. However, they can be corroded in the oral cavity that is very complicated environments. In this study, Ti G2 and G3, gold, silver, Co-Cr and Ni-Cr alloys were investigated for their corrosion resistances and phenomena. Potentiodynamic and potentiostatic tests(open circuit potential and current density at-250, 0 and 250 mV(SCE) were performed in artificial saliva at 37℃. Corrosion of gold and silver alloys did not occur in artificial saliva due to their i㎜unity in this environment. Co-Cr, Ni-Cr and pure Ti exhibited the high corrosion resistance by their own passivity. Gold, silver and Ti G2 exhibited the highest corrosion resistance, Ni-Cr alloy and Ti G3 did the relatively high corrosion resistance, and Co-Cr alloy did the low corrosion resistance. The open circuit potentials of gold, Ti G2, Ni-Cr and silver alloys were about 50, 20, 0 and -60 mV(SCE), respectively. The open circuit potentials of Ti G3 and Co-Cr decreased with the i㎜ersion time. In the potential loading of -250 mV, cathodic current flowed to all samples, although the absolute values were different. In the potential loading of 0 mV, cathodic current flowed to the others except for Co-Cr alloy. Ti G2 and Co-Cr alloys showed anodic current and the others cathodic current in the potential loading of 250 mV. If the pure Ti is used as dental implant in the oral cavity, gold and silver alloys are considered to minimize the adverse effects by galvanic corrosion, but the galvanic corrosion as well as the localized corrosion such as pitting or crevice corrosion can be occurred in Co-Cr alloy.

Surface characteristics of titanium–silver alloys in artificial saliva

Shim, H. M.,Oh, K. T.,Woo, J. Y.,Hwang, C. J.,Kim, K. N. Heyden & Son 2006 Surface and interface analysis Vol.38 No.1

<P>Titanium and its alloys are widely used in biomedical and dental fields because of their excellent corrosion resistance and biocompatibility. It is well known that titanium is protected from corrosion because of the stability of the passive film that controls and determines the corrosion resistance and biocompatibility of titanium and its alloys. The purpose of this study was to evaluate the electrochemical properties of titanium–silver alloys and the surface characteristics of passive film in artificial saliva.</P><P>We designed titanium–silver alloys with silver contents ranging from 0 to 5 at.%, in 1% increments. These alloys were arc-melted, homogenized, hot-rolled to 2 mm thickness, and finally solution heat-treated for 1 h and quenched. Potentiostatic testing was performed, and the open circuit potentials of the alloys were measured in artificial saliva, at 37 °C. The passive films of the titanium–silver alloys were analyzed via XPS.</P><P>Titanium–silver alloys maintained low current density and showed stable passive region and also had high open circuit potential as compared with pure titanium. The open circuit potential of titanium–silver alloys increased as silver addition increased. With regard to the fraction of oxygen species, a component of over 80% was found to be comprised of oxide. Therefore, the titanium surface mainly consisted of titanium oxide and, on the titanium–silver alloys, this film was composed of TiO<SUB>2</SUB>, Ti<SUB>2</SUB>O<SUB>3</SUB>, and TiO. As silver content increased, the TiO<SUB>2</SUB> fraction also increased, as did the thickness of the titanium oxide layer formed. Copyright © 2005 John Wiley & Sons, Ltd.</P>

Physico-mechanical properties and prosthodontic applications of Co-Cr dental alloys : a review of the literature

Youssef S. Al Jabbari/ 대한치과보철학회 2014 The Journal of Advanced Prosthodontics Vol.6 No.2

Cobalt-Chromium (Co-Cr) alloys are classified as predominantly base-metal alloys and are widely known for their biomedical applications in the orthopedic and dental fields. In dentistry, Co-Cr alloys are commonly used for the fabrication of metallic frameworks of removable partial dentures and recently have been used as metallic substructures for the fabrication of porcelain-fused-to-metal restorations and implant frameworks. The increased worldwide interest in utilizing Co-Cr alloys for dental applications is related to their low cost and adequate physico-mechanical properties. Additionally, among base-metal alloys, Co-Cr alloys are used more frequently in many countries to replace Nickel-Chromium (Ni-Cr) alloys. This is mainly due to the increased concern regarding the toxic effects of Ni on the human body when alloys containing Ni are exposed to the oral cavity. This review article describes dental applications, metallurgical characterization, and physico-mechanical properties of Co-Cr alloys and also addresses their clinical and laboratory behavior in relation to those properties.

Strengthening of Al_0.15CoCrCuFeNiTi_<i>x</i>–C (<i>x</i> = 0, 1, 2) high-entropy alloys by grain refinement and using nanoscale carbides via powder metallurgical route

Nam, Seungjin,Kim, Moon J.,Hwang, Jun Yeon,Choi, Hyunjoo Elsevier 2018 JOURNAL OF ALLOYS AND COMPOUNDS Vol.762 No.-

<P><B>Abstract</B></P> <P>In this study, Al<SUB>0.15</SUB>CoCrCuFeNiTi<SUB> <I>x</I> </SUB>–C (<I>x</I> = 0, 1, 2) high-entropy alloys (HEAs) were produced via powder metallurgy routes, and the microstructural evolution and mechanical properties of the alloys were investigated with respect to the alloys of Ti content. Cr-carbides were formed in the Ti-free alloy, whereas the Ti-containing alloys contained Ti-carbides instead of Cr-carbides because Ti has a higher affinity for C than it does for Cr. Sigma phases were also formed in the Al<SUB>0.15</SUB>CoCrCuFeNiTi<SUB>2</SUB>-C alloy. The formation of carbides and intermetallic compounds altered the composition and structure of the solid-solution phases. High-energy ball-milling led to the refinement of microstructures to the nanoscale, and the average grain size of the alloys decreased with increasing Ti content because of the grain-boundary pinning effect of TiC. As a result, the Al<SUB>0.15</SUB>CoCrCuFeNiTi<SUB> <I>x</I> </SUB>–C (<I>x</I> = 0, 1, 2) alloys exhibited high strengths of 2047, 2199, and 2877 MPa, respectively.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Al<SUB>0.15</SUB>CoCrCuFeNiTi<SUB>x</SUB>-C HEAs were fabricated via powder metallurgy. </LI> <LI> Microstructural evolution and mechanical properties of the alloys were investigated. </LI> <LI> Different carbides were formed in the alloy depending on Ti content. </LI> <LI> Al<SUB>0.15</SUB>CoCrCuFeNiTi<SUB>2</SUB>-C alloy revealed solid-solution phases, carbide, and intermetallic compound. </LI> <LI> Al<SUB>0.15</SUB>CoCrCuFeNiTi<SUB>2</SUB>-C alloy shown the outstanding specific yield strength of 0.429 MPa/kg·m<SUP>3</SUP>. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>