• Title/Summary/Keyword: Metallic biomaterials

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Miscibility Gap in Cu-Zr-Ag Alloy System and its Effect on the Structure and Plasticity of Metallic Glass (Cu-Zr-Ag계 비정질 합금의 불혼화 영역이 구조 및 소성에 미치는 영향)

  • Lee, Jin-ju;Park, Kyoung-Won;Kim, Do-Hyang;Fleury, Eric
    • Korean Journal of Metals and Materials
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    • v.49 no.12
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    • pp.930-936
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    • 2011
  • In the present study, we show that the addition of Ag, an element having a positive enthalpy of mixing with Cu in the liquid state, enables the simultaneous enhancement of the glass forming ability and the plasticity in Cu-Zr-Ag bulk metallic glasses (BMGs). Rods of 4 mm diameter could be prepared with a fully amorphous structure and values of plastic strain up to 18% were measured under a compression mode for compositions around $Cu_{42.5}Zr_{47.5}Ag_{10}$. The possible role of Ag in the change of the atomic structure and the enhancement of the plastic strain in the ternary Cu-Zr-Ag BMGs is discussed based on analyses from transmission electron microscopy and EXAFS (extended X-ray absorption fine structure).

Si and Mg Coatings on the Hydroxyapatite Film Formed Ti-29Nb-xHf Alloys by Plasma Electrolyte Oxidation

  • Park, Seon-Yeong;Choe, Han-Cheol
    • Proceedings of the Korean Institute of Surface Engineering Conference
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    • 2017.05a
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    • pp.152-152
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    • 2017
  • Titanium and its alloys have been widely used for biomedical applications. However, the use of the Ti-6Al-4V alloy in biomaterial is then a subject of controversy because aluminum ions and vanadium oxide have potential detrimental influence on the human body due to vanadium and aluminum. Hence, recent works showed that the synthesis of new Ti-based alloys for implant application involves more biocompatible metallic alloying element,such as, Nb, Hf, Zr and Mo. In particular, Nb and Hf are one of the most effective Ti ${\beta}$-stabilizer and reducing the elastic modulus. Plasma electrolyte oxidation (PEO) is known as excellent method in the biocompatibility of biomaterial due to quickly coating time and controlled coating condition. The anodized oxide layer and diameter modulation of Ti alloys can be obtained function of improvement of cell adhesion. Silicon (Si) and magnesium (Mg) has a beneficial effect on bone. Si in particular has been found to be essential for normal bone and cartilage growth and development. In vitro studies have shown that Mg plays very important roles in essential for normal growth and metabolism of skeletal tissue in vertebrates and can be detected as minor constituents in teeth and bone. Therefore, in this study, Si and Mg coatings on the hydroxyapatite film formed Ti-29Nb-xHf alloys by plasma electrolyte oxidation has been investigated using several experimental techniques. Ti-29Nb-xHf (x= 0, 3, 7 and 15wt%, mass fraction) alloys were prepared Ti-29Nb-xHf alloys of containing Hf up from 0 wt% to 15 wt% were melted by using a vacuum furnace. Ti-29Nb-xHf alloys were homogenized for 2 hr at $1050^{\circ}C$. The electrolyte was Si and Mg ions containing calcium acetate monohydrate + calcium glycerophosphate at room temperature. The microstructure, phase and composition of Si and Mg coated oxide surface of Ti-29Nb-xHf alloys were examined by FE-SEM, EDS, and XRD.

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Ceramic color differences of dental Ni-Cr alloy by compositional change (치과용 Ni-Cr 합금의 조성에 따른 세라믹의 색차 분석)

  • Kim, Sa-Im;Kim, Tae-Yeon;Kim, Se-Ha;Kang, Jeong-Gyu;Lee, Jung-Hwan
    • Journal of Technologic Dentistry
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    • v.43 no.4
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    • pp.168-174
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    • 2021
  • Purpose: This study was conducted to investigate alloys spectrophotometrically including yttrium of nickel-chromium (Ni-Cr) alloys, which are used as substitutes for the regulation of beryllium and provide helpful improvements in Ni-Cr alloys. Methods: Four groups of specimens (ZN, ZY, SN and EM) were prepared for analysis. Color parameters were measured with a spectrophotometer, and color difference (∆E*) was calculated. The t-test and one-way analysis of variance test were used to determine significant difference, and the Tukey test was used to identify where the differences were. To measure the spectroscopic reflectivity, the spectroscopic reflectance was measured and converted into CIE L*, a*, b* color system. Results: The ∆E* value of each metal ceramic group after opaque firing of Ni-Cr alloy with and without yttrium was <2, and the total group color difference (∆E*) was below 1 in the dentin ceramic all experimental group. However, the a* and b* values of the metal ceramic groups were higher than that in the lithium disilicate all ceramic group, and the chroma was higher than the natural tooth. The brightness of all experimental groups was similar to that of the shade guide sample. Conclusion: Yttrium added to Ni-Cr alloys showed similar CIE L*, a*, b* values to Ni-Cr alloys that did not contain yttrium, indicating that yttrium had no effect on color in metallic ceramic systems.

Development of Eco-friendly Lead Substitute Materials (친환경 납추 대체소재 개발)

  • Gwon, Jin Uk;Song, Hee Jin;Hwang, Dae Youn;Kim, Hye Sung
    • Journal of the Korean Society for Heat Treatment
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    • v.35 no.3
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    • pp.130-138
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    • 2022
  • In this study, the characteristic of an amorphous fishing weight material according to controlling the alloy type and alloy composition of the glass forming agent added in PbO2 oxide was investigated. According to the experimental, when the glass forming agent of 15wt%SiO2-1wt%MgO content was added in β-PbO2, an amorphous fishing weight substitute having the lowest friction coefficient, excellent corrosion resistance and durability was obtained. The cell number of PbO2-15wt%SiO2-1wt%MgO sample incubated in cell culture fluid tended to hardly decrease even after a lapse of 24 hours, It means that the fabricated PbO2-15wt%SiO2-1wt%MgO sample is significantly less-toxic and harmless to the human body, unlikely to metallic lead. It is considered that an fabricated amorphous fishing weight substitute proved to have a potential as an eco-friendly material with little marine pollution.

Surface Characteristics of TiN and ZrN Film Coated STD 61 by Sputtering (스퍼터링법으로 TiN 및 ZrN 피막 코팅된 STD 61의 표면특성)

  • Eun, Sang-Won;Choe, Han-Cheol
    • Journal of the Korean institute of surface engineering
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    • v.43 no.6
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    • pp.260-265
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    • 2010
  • STD 61 steel has been widely used for tools, metallic mold and die for press working because of its favorable mechanical properties such as high toughness, and creep strength as well as excellent oxidation resistance. The STD 61 tool steel coated with TiN and ZrN by sputtering results in improvement of wear and corrosion resistance. In this study, surface characteristics of TiN and ZrN film coated STD 61 by sputtering were studied by using FE-SEM, EDS, XRD, and XRR and nanoindentation tests. From the results of surface characteristics of coated specimen, the ZrN coated surface showed finer granular than that of TiN coated surface. The coated layer structures of ZrN and TiN were grown to (111) and (200) preferred orientation. From the results of XRR test for surface roughness, density and growth rate of coating film, surface roughness and growth rate of ZrN coated film revealed lower values those of TiN coated film, whereas density of ZrN coated film showed higher values than that of TiN coated film. From the nanohardness and elastic modulus test, nanohardness value and elastic modulus of ZrN coated film became higher than those of TiN coated film.

Surface Characteristics of Metallic 3D Printed Dental Framework (금속 3D printing으로 제작한 치과보철물의 표면특성)

  • Choe, Han-Cheol
    • Proceedings of the Korean Institute of Surface Engineering Conference
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    • 2018.06a
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    • pp.21-21
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    • 2018
  • 다양한 소재(금속, 세라믹, 고분자 소재 등)들이 3차원 형상기반 적층제조법에 적용되고 있는데, 금속 소재를 이용하여 3D 프린팅 법으로 치과용 수복물을 제조하는 연구가 많이 보고되고 있다. 하지만, 티타늄 또는 티타늄 합금 분말을 이용하여 3D 프린팅 법으로 제작한 치과용 보철물에 관한연구 보고는 많지 않다. Kanazawa 등 (2014)은 Ti-6Al-4V 합금분말을 이용하여 SLM법으로 총의치 용 framework를 제작하여 주조법으로 제작한 것과 비교 평가하였고, Mangano 등(2013)은 Ti-6Al-4V 합금분말로 지름이 작은 일체형 (1-piece narrow-diameter) 임플란트를 SLS법으로 제작하여 16명의 환자에게 식립한 다음, 2년간 관찰하였고, Mangano 등 (2014)은 cone-beam computed tomography (CBCT) data를 3D이미지로 변환시켜 DLMS법으로 치근 형상의 임플란트를 제작하여 15명의 환자에게 식립한 다음, 1년간 관찰하였다. 또한 서울대학교 및 연세대학교 치과생체재료과학교실 (2016)에서는 3D 프린팅 법으로 제작한 티타늄 시편과 기계 가공한 티타늄 시편의 물성을 비교하였다. 그러나 티타늄 합금 분말을 이용하여 3D 프린팅 법으로 제작한 치과용 보철물을 실제 임상에 적용하는 단계에서 기존 기계가공 방식으로 제작한 티타늄 보철물과 3D 프린팅 법으로 제작한 티타늄 보철물의 물성과 표면특성을 다양하게 비교 평가하는 것이 필요하여 본 연구에서는 3D 프린팅 법으로 제작한 티타늄 시편과 기계 가공한 티타늄 시편의 물성특성과 표면특성을 비교하여 조사하였다.

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PHASE TRANSITIONS AND ELECTROCHEMICAL CORROSION BEHAVIORS OF Ti50Ni50-xCux SHAPE MEMORY ALLOYS FOR METALLIC BIOMATERIALS

  • KWANGMIN LEE;SANGHYUN RHO
    • Archives of Metallurgy and Materials
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    • v.65 no.4
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    • pp.1303-1306
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    • 2020
  • TiNi alloys have excellent shape memory properties and corrosion resistance as well as high biocompatibility. This study investigated the effects of copper addition on the phase transitions and electrochemical corrosion behaviors of Ti50Ni50-xCux alloys. TiNi, Ti50Ni47Cu3, Ti50Ni44Cu6, and Ti50Ni41Cu9 alloys were prepared using vacuum arc remelting followed by 4 h homogenization at 950℃. Differential scanning calorimetry and X-ray diffraction analyses were conducted. The corrosion behaviors of the alloys were evaluated using potentiodynamic polarization test in Hank's balanced salt solution at a temperature of 36.5 ± 1℃. The TiNi alloy showed phase transitions from the cubic B2 phase to the monoclinic B19' phase when the alloy was thermally cycled. The addition of copper to the TiNi alloy played a major role in stabilizing the orthorhombic B19 phases during the phase transitions of Ti50Ni50-xCux alloys. The shifts in the corrosion potential toward the positive zone and the low corrosion current density were affected by the amount of Cu added. The corrosion resistance of the TiNi alloy increased with increasing copper content.

Si and Mg doped Hydroxyapatite Film Formation by Plasma Electrolytic Oxidation

  • Park, Seon-Yeong;Choe, Han-Cheol
    • Proceedings of the Korean Institute of Surface Engineering Conference
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    • 2016.11a
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    • pp.195-195
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    • 2016
  • Titanium and its alloys are widely used as implants in orthopedics, dentistry and cardiology due to their outstanding properties, such as high strength, high level of hemocompatibility and enhanced biocompatibility. Hence, recent works showed that the synthesis of new Ti-based alloys for implant application involves more biocompatible metallic alloying element, such as, Nb, Hf, Zr and Mo. In particular, Nb and Hf are one of the most effective Ti ${\beta}-stabilizer$ and reducing the elastic modulus. Plasma electrolyte oxidation (PEO) is known as excellent method in the biocompatibility of biomaterial due to quickly coating time and controlled coating condition. The anodized oxide layer and diameter modulation of Ti alloys can be obtained function of improvement of cell adhesion. Silicon (Si) and magnesium (Mg) has a beneficial effect on bone. Si in particular has been found to be essential for normal bone and cartilage growth and development. In vitro studies have shown that Mg plays very important roles in essential for normal growth and metabolism of skeletal tissue in vertebrates and can be detected as minor constituents in teeth and bone. The aim of this study is to research Si and Mg doped hydroxyapatite film formation by plasma electrolytic oxidation. Ti-29Nb-xHf (x= 0, 3, 7 and 15wt%, mass fraction) alloys were prepared Ti-29Nb-xHf alloys of containing Hf up from 0 wt% to 15 wt% were melted by using a vacuum furnace. Ti-29Nb-xHf alloys were homogenized for 2 hr at $1050^{\circ}C$. Each alloy was anodized in solution containing typically 0.15 M calcium acetate monohydrate + 0.02 M calcium glycerophosphate at room temperature. A direct current power source was used for the process of anodization. Anodized alloys was prepared using 270V~300V anodization voltage at room. A Si and Mg coating was produced by RF-magnetron sputtering system. RF power of 100W was applied to the target for 1h at room temperature. The microstructure, phase and composition of Si and Mg coated oxide surface of Ti-29Nb-xHf alloys were examined by FE-SEM, EDS, and XRD.

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Morphology of Bone-like Apatite Formation on Sr and Si-doped Hydroxyapatite Surface of Ti-6Al-4V Alloy after Plasma Electrolytic Oxidation

  • Yu, Ji-Min;Choe, Han-Cheol
    • Proceedings of the Korean Institute of Surface Engineering Conference
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    • 2017.05a
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    • pp.79-79
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    • 2017
  • Metallic biomaterials have been mainly used for the fabrication of medical devices for the replacement of hard tissue such as artificial hip joints, bone plates, and dental implants. Because they are very reliable on the viewpoint of mechanical performance. This trend is expected to continue. Especially, Ti and Ti alloys are bioinert. So, they do not chemically bond to the bone, whereas they physically bond with bone tissue. For their poor surface biocompatibility, the surface of Ti alloys has to be modified to improve the surface osteoinductivity. Recently, ceramic-like coatings on titanium, produced by plasma electrolytic oxidation (PEO), have been developed with calciumand phosphorus-enriched surfaces. A lso included the influences of coatings, which can accelerate healing and cell integration, as well as improve tribological properties. However, the adhesions of these coatings to the Ti surface need to be improved for clinical use. Particularly Silicon (Si) has been found to be essential for normal bone, cartilage growth and development. This hydroxyapatite, modified with the inclusion of small concentrations of silicon has been demonstrating to improve the osteoblast proliferation and the bone extracellular matrix production. Strontium-containing hydroxyapatite (Sr-HA) was designed as a filling material to improve the biocompatibility of bone cement. In vitro, the presence of strontium in the coating enhances osteoblast activity and differentiation, whereas it inhibits osteoclast production and proliferation. The objective of this work was to study Morphology of bone-like apatite formation on Sr and Si-doped hydroxyapatite surface of Ti-6Al-4V alloy after plasma electrolytic oxidation. Anodized alloys was prepared at 270V~300V voltages with various concentrations of Si and Sr ions. Bone-like apatite formation was carried out in SBF solution. The morphology of PEO, phase and composition of oxide surface of Ti-6Al-4V alloys were examined by FE-SEM, EDS, and XRD.

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Corrosion and Oxidation Behaviors of ion-nitrided tool Steels (이온질화된 공구강 표면의 산화 및 공식거동)

  • Choe Han-Cheol;Lee Ho-Jong;Jeong Yong-Woon
    • Journal of the Korean institute of surface engineering
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    • v.38 no.3
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    • pp.126-135
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    • 2005
  • SKD 11 steel has been widely used for tools, metallic mold and die for press working because of its favorable mechanical properties such as high toughness and creep strength as well as excellent oxidation resistance. The ion nitrided tool steel containing Mo results in improvement of corrosion resistance, strength at high temperature and pitting resistance, especially in $Cl^-$ contained environment. But the Mo addition causes a disadvantage such as lower oxidation resistance at elevated temperature. In this study, several effects of ion-disadvantage on the oxidation characteristics for SKD 11 steel with various oxidation temperature were investigated. SKD 11 steels were manufactured by using vacuum furnace and solutionized for 1 hr at $1,050^{\circ}C$. Steel surface was ion nitrided at $500^{\circ}C$ for 1 hr and 5 hr by ion nitriding equipment. ion nitrided specimen were investigated by SEM, OM and hardness tester. Oxidation was carried out by using muffle furnace in air at $500^{\circ}C,\;700^{\circ}C\;and\;900^{\circ}C$ for 1hr, respectively. Oxidation behavior of the ion nitrided specimen was investigated by SEM, EDX and surface roughness tester. The conclusions of this study are as follows: It was found that plasma nitriding for 5 hr at $500^{\circ}C$, compared with ion nitriding for 1 hr at $500^{\circ}C$, had a thick nitrided layer and produced a layer with good wear, corrosion resistance and hardness as nitriding time increased. Nitrided SKD 11 alloy for 1hr showed that wear resistance and hardness decreased, whereas surface roughness increased, compared with nitrided SKD 11 alloy for 5 hr. The oxidation surface at $900^{\circ}C$ showed a good corrosion resistance.