• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2018.06a
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• pp.75-75
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• 2018

Commercially pure titanium (CP-Ti) and Ti-6Al-4V alloys have been widely used in implant materials such as dental and orthopedic implants due to their corrosion resistance, biocompatibility, and good mechanical properties. However, surface modification of titanium and titanium alloys is necessary to improve osseointegration between implant surface and bone. Especially, when titanium oxide nanotubes are formed on the surface of titanium alloy, cell adhesion is greatly improved. In addition, plasma electrolytic oxide (PEO) coatings have a good safety for osseointegration and can easily and quickly form coatings of uniform thickness with various pore sizes. Recently, the effects of bone element such as magnesium, zinc, strontium, silicon, and manganese for bone regeneration are researching in dental implant field. The purpose of this study was researched on the surface morphology of PEO-treated Ti-6Al-4V alloy after anodic titanium oxide treatmentusing various instruments. Ti-6Al-4V ELI disks were used as specimens for nanotube formation and PEO-treatment. The solution for the nanotube formation experiment was 1 M $H_3PO_4$ + 0.8 wt. % NaF electrolyte was used. The applied potential was 30V for 1 hours. The PEO treatment was performed after removing the nanotubes by ultrasonics for 10 minutes. The PEO treatment after removal of the nanotubes was carried out in the $Ca(CH_3)_2{\cdot}H_2O+(CH_3COO)_2Mg{\cdot}4H_2O+Mn(CH_3COO)_2{\cdot}4H_2O+Zn(CH_3CO_2)_2Zn{\cdot}2H_2O+Sr(CH_2COO)_2{\cdot}0.5H_2O+C_3H_7CaO_6P$ and $Na_2SiO_3{\cdot}9H_2O$ electrolytes. And the PEO-treatment time and potential were 3 minutes at 280V. The morphology changes of the coatings on Ti-6Al-4V alloy surface were observed using FE-SEM, EDS, XRD, AFM, and scratch tester. The morphology of PEO-treated surface in 5 ion coating solution after nanotube removal showed formation or nano-sized mesh and micro-sized pores.

• Korean Journal of Materials Research
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• v.7 no.1
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• pp.50-56
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• 1997

급냉응고법을 이용하여 고용한도 이상으로 Mn량을 첨가할 때 Mn량에 따른 인장특성의 변화와 시효특성을 조사하였다. 원심분무법으로 AI-4.7%Zn-2.5%Mg-0.2%Zr합금에 Mn량을 각기 달리 첨가한 급냉응고 분말을 제조 하였다. 이 분말을 냉간압축, 진공 탈가스처리를 한 후 15:1로 압출하여 봉상 시편을 만들었다. 분말의 미세조직은 $\alpha$-AI수지상과 수지상간 편석부로 이루어져 있으며 Mn첨가에 따라 조직의 변화는 관찰되지 않았다. 빠른 냉각속도로 인하여 2.0%Mn을 첨가한 경우에도 초정 Mn상을 발견할 수 없었다. 압출재의 미세조직은 아결정립으로 이루어져 있으며 약간의 제2상들이 관찰되었다. 대부분의 Mn 분산상은 압출후 용체화처리 과정에서 형성되었으며 시효경화량은 Mn양에 관계없이 일정하였다. 46$0^{\circ}C$에서 1시간 용체화처리하고 12$0^{\circ}C$에서 24시간 시효처리한 경우 최대의 시효경도값을 나타내었다. 인장강도는 Mn첨가량에 따라 증가 하였는데 이것은 Mn분산상의 밀도증가에 의한 것으로 확인되었다. 2.0%Mn을 첨가한 합금의 시효후 인장강도는 590MPa, 연산율은 4%를 보였다.

• Proceedings of the KWS Conference
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• 2007.11a
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• pp.322-324
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• 2007

Nd:YAG laser welding of AZ31B-H24 magnesium alloy was carried out using AZ61 filler wire(Mg-6wt%Al-1wt%Zn). Microstructure and mechanical properties of welded joint were examined by optical microscopy, scanning electronic microscopy(SEM), energy dispersive spectroscopy(EDS), electron probe micro analyzer(EPMA) and victors hardness, tensile test at the room and elevated temperature. Test results indicate that the specimens welded with AZ61 filler wire have better tensile strength, elongation and victors hardness at room temperature than those of welded without filler wire. However tensile strength are similar but elongation are quite different at elevated temperature.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2017.05a
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• pp.153-153
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• 2017

The application of the coating supports the mechanical characteristics of the implant, and various materials and coatings are currently being used in the implant in a way to accelerate adhesion. Especially, plasma electrolytic oxidation (PEO) coating has been proposed continually with good surface treatment of titanium alloys. Also, the PEO process can incorporate Ca and P ions on the titanium surface through variables varied factor. PEO process for bioactive surface has carried out in electrolytes containing Ca and P ions. Natural bone is composed of mineral elements such as Mg, Si, Zn, Sr, and Mn, etc. Especially, Mg and Si of these elements play role in bone formation and growth after clinical implantation of bio-implants. In this study, corrosion charateristics of PEO-treated Ti-6Al-4V alloy in solution containing Si and Mg ions has been investigated using several experimental techniques. The PEO-treated surfaces were identified by X-ray diffraction, using a diffractometer (XRD, Philips X' pert PRO, Netherlands) with Cu $K{\alpha}$ radiation. The morphology was observed by field-emission scanning electron microscopy (FE-SEM, Hitachi 4800, Japan) and energy-dispersive X-ray spectroscopy (EDX, Oxford ISIS 310, England). The potentiodynamic polarization and AC impedance tests for electrochemical degradations were carried out in 0.9% NaCl solution at similar body temperature using a potentiostat with a scan rate of 1.67mV/s and potential range from -1500mV to + 2000mV.

• Journal of Electrochemical Science and Technology
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• v.11 no.4
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• pp.323-329
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• 2020

The cathodic hydrogen evolution ability of different pure metals and their long term galvanic corrosion behavior with pure Mg were investigated. The hydrogen evolution ability of pure Ti, Al, Sn and Zr is weak, while that of Fe, W, Cr, and Co is very strong. Initial polarization test could not completely reveal the cathodic behavior of the tested metals during long term corrosion. The cathodic hydrogen evolution ability may vary significantly in the long term galvanic tests for different metals, especially for Al whose cathodic current density reduced to 1/50 of the initial value. The anodic polarization shows that Al and Sn as alloying elements are supposed to provide relatively good passive effect for Mg alloy, while Ag can provide a slight passive effect and Zn has little passive effect.

• Journal of the Korean Society for Heat Treatment
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• v.17 no.5
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• pp.299-304
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• 2004

Influence of Ca addition on microstructure and room temperature mechanical properties has been studied for AZ31(Mg-3%Al-1%Zn-0.2%Mn)-(0~0.5)%Ca wrought alloys, based on experimental results from metallography, X-ray diffractometry and mechanical tests. Yield strength, ultimate tensile strength and hardness of the alloys increased remarkably with increasing Ca content, whereas elongation was deteriorated continuously. Microstructural examination revealed that Ca addition efficiently refined grains of ${\alpha}$(Mg) phase and that some of the Ca dissolved in ${\beta}(Mg_{17}Al_{12})$ precipitates. The former and the latter facts are thought to be responsible for improved strength and loss of ductility of the AZ31+Ca wrought alloys, respectively.

• Journal of Welding and Joining
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• v.30 no.6
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• pp.56-61
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• 2012

Magnesium alloy sheet which is commercially available in the market presently is AZ31B, a Mg-Al-Zn three elements alloy. AZ31B is used by being classified into AZ31B-H24 and AZ31B-O depending on temper designation. In this study, AZ31B-H24 and AZ31B-O alloy sheets with 1.25mm thickness were butt-welded using CW Nd:YAG laser. And the effect of materials on mechanical properties was investigated by tensile and hardness tests. As a result of this study, regardless of materials, the butt-welded joint did not show a significant difference in tensile strength and hardness values. However, compared with the basemetal, the AZ31B-O showed more outstanding mechanical properties than AZ31B-H24, and that is because H24 material lost the effect of work hardening during welding.

• Journal of the Korean Society for Heat Treatment
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• v.33 no.2
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• pp.49-56
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• 2020

Magnesium alloy is a metal with high specific strength and light weight, and is attracting attention as a next generation metal for environmentally friendly automobiles and transportation equipment. However, magnesium alloys have a problem of degrading formability due to the basal texture developed during processing, and their application is limited. Although active researches on the control of textures have been conducted in order to minimize this problem, there is a lack of research on the formation of microstructures and textures according to elemental differences. In this study, AZ61 and AZ80 magnesium alloys were selected to investigate the effects of aluminum addition on the microstructure development of magnesium alloys. This research has proven that the increase of the rolling rate results in the decrease of the average grain size of the two alloys, the increase of the hardness, and the increase of the fraction of twins. As shown on this research below, the basal texture developed strongly as the rolling ratio increased. On the other hand, this research also has proven that the two alloys exhibited different texture strength and distribution tendencies, which could be due to the effects of aluminum addition on work hardening, grain size, and twin behavior.

• Proceedings of the Materials Research Society of Korea Conference
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• 1992.05a
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• pp.14-14
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• 1992

During the past five years a very successful effort has been made to improve existing and develop new aluminium alloys. The progress achieved has been possible because of the development of new production methods, such as powder metallurgy and spray/deposition. These methods make use of rapid solidification process which alloys compositions other than those achieved by conventional ingot metallurgy. The ingot metallurgy of the 2000 and 7000 series used thus far, as well as the age hardening Al-Li alloys, show several disadvantages caused by the production process. Such problems are primarily coarse intermetallic constituent phases, coarse grains and macrosegregation, resulting in low fracture toughness. The present contribution reports results of an experimental investigation performed on a modern high strength spay deposited aluminium alloy of the Al-Zn-Mg-Cu (7075 and the modified 7150X) type. Results are given in terms of its microstructural characterization by using X-ray diffractomertry and transmission electron microscopic. The mechanical propierties of those alloys in the as-extruded and extruded+aged condition were evaluated by using microhardness Vickers, tensile test and fracture toughness measurements.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.710-711
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• 2006

High strength PM aluminium alloys Al-Zn-Mg-Cu (7075 type) were studied by using commercially available powder blends and the sinter-forging technique for component production. Principal areas of focus include the response to PM processing, micro structural assessment and material properties of Aluminium sinter forged products. Green preforms are successfully sintered to near full density by solid-supersolidus liquid phase sintering. Sinter forging method can produce components with net shape and mechanical characteristics of the material have improved greatly. Properties of this new PM Al-alloy were found to be reproducible in an industrial production environment.