• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2015년도 추계학술대회 논문집
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• pp.137-137
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• 2015

The purposed of this work was to observe hydroxyapatite precipitation phenomena on micro-pore formed Ti-Nb alloy by PEO technique. The Ti-30Nb and Ti-30Ta alloys were remelted at least ten times in order to avoid inhomogeneity, and then cylindrical specimens (diameter 10 mm, thickness 4 mm) were cut by using laser from cast ingots of the Ti alloys. Heat treatment was carried out at $1050^{\circ}C$ for 2 h for homogenization in argon atmosphere. The morphologic change of the alloys were examined by X-ray diffractometer (XRD) and field emission scanning electron microscopy (FE-SEM).

• 대한치과의사협회지
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• 제9권6호
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• pp.293-296
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• 1971

Histochemical observations on the effect of gold alloys crown margin in the periodontal membrane were caried out by use of rabbits. The animal were setted with gold alloys crown on the incisor teeth. The cervical margins were given extence into gingival sockets. The animals were sacrificed at the 30 days experimented period. Specimens of tissue were obtained from the mandibular incisor teeth with jaw. All tissues were fixed immediately in 10% neutral formalin solution. Different histochemical staining methods for the determination of fibrous components were the Mallory-Heidenhain Bielschowsky-Gomori, Gomori's aldehyde fuchsin. Periodic acid-Schiff reaction and Hematoxylin eosin stanin method. The results were as follows. The periodontal membrane is composed primarily of collagenous fibers and fibrous component run functional arrangement but in lower gold content groups, horizontal fiber groups were irregularly run. Elastic fibers were obligue run in experimental groups. There were no significant differences in reticularfibers in distribution.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2013년도 춘계학술대회 논문집
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• pp.194-194
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• 2013

In order to investigate nanotube morphology change of Ti-6Al-4V alloys by heat treatments, the Ti-6Al-4V alloys were used in this study. In non-treated Ti-6Al-4V alloy case, nanotubes only exhibited at ${\alpha}$ phase region with dissolved V-oxide area of ${\beta}$ phase. However, in Ti-6Al-4V alloy at $800^{\circ}C$ WQ case, nanotubes exhibited at both ${\alpha}$ and ${\beta}$ phase region. Electrochemical corrosion studies showed that the nanotubular alloy at $800^{\circ}C$WQ possesses slightly higher corrosion resistance than non-treated nanotubular alloy.

• 한국주조공학회지
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• 제11권6호
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• pp.482-490
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• 1991

This study presents the wear characteristics of Ti alloys (Pure Ti, Ti-6Al-4V, Ti-5Al-2.5Sn) fabricated by centrifugal precision casting in an Ohara dental titanium casting machine. It was found that the hardness of the surface region is higher than that of the interior region. It is considered that the oxygen adsorption in the surface region during casting, leads to the interstitial solid solution hardening. Wear resistance incerases in the order of pure Ti, Ti-6Al-4V, Ti-5Al-2.5Sn alloys. The interior hardness value increases in the same order. The specific wear rate increases with applied load and increases monotonously with sliding speed. The Fe transfer from the counterpart material was observed on the worn surface of the Ti-5Al-2.5Sn alloy. Oxidative wear occurs at low sliding speeds and mechanical fracture wear occurs at high sliding speeds.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2015년도 춘계학술대회 논문집
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• pp.106-106
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• 2015

In this study, we investigated electrochemically formed nanotube shape on ternary Ti-25Ta-xHf alloys with Hf contents. Ti-25Ta-xHf (x=0~15 wt.%) alloys were manufactured by vacuum arc-melting furnace. The obtained ingots were homogenized in an argon atmosphere at $1050^{\circ}C$ for 2h and then water quenching. The specimens were cut from ingots to 4 mm thickness and first ground and polished using SiC paper (grades from #100 to #2000). The anodization treatments on Ti-25Nb-xHf alloys were carried out at room temperature for experiments. The formation of nanotubular film was conducted by electrochemical method in mixed electrolytes with 1 M $H_3PO_4$ + 0.8 wt. % NaF at 30 V for 2 h. The morphologies of nanotube depended on the Hf content in Ti-25Ta-xHf ternary system.

• 대한치과기공학회지
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• 제31권3호
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• pp.21-26
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• 2009

Purpose: Standards of alloy for porcelain fused to metal crown be classified by metallic factor and biological factor. Metallic factors consist of stability of alloy composition and mechanical strength and surface characteristics for chemical bond. Biological factors be considered properties of metallic elements and problems originated by toxicity and hypersensitive reaction. Alloys considered such controversial points are the most suitable alloy for dental instrument. Method: Alloys added Be and Nb using Ni-Cr alloy which has been widely used for dental instrument be selected and classified experimental group. Non-addition Be and Nb to Ni-Cr alloy classify control group and addition Be alloy is Be-experimental group, addition Nb alloy is Nb-experimental group. Specimens for cytotoxicity analysis gave effect to washing and sterilization. and then made an experiment on elution with cell medium after disinfection. It conducted specimens within cell medium with 24hours, 48hours, 72hours, respectively. It cultured human dermal fibroblast(HDF) using cell medium for cytotoxicity test and then investigated elution rate through spectroscopic analysis by MTT-assay. Result: As results of cytotoxicity test by MTT-assay, cultured cell rate of VII measured more low numerical value within elution medium for 24hours focused on control group. Also, cultured cell rate of K3 alloys observed low value for 48hours, 72hours than value of control group. Conclusion: According to final result that synthesize above results, Ni-Cr alloy added Be and Ni has little difference in Cytotoxicity by MTT-assay.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2015년도 춘계학술대회 논문집
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• pp.63-63
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• 2015

• 대한치과보철학회지
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• 제59권2호
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• pp.248-260
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• 2021

코발트-크롬 합금은 다양한 치과보철물 제작에 이용되고 있고, 다른 합금에 비해 저렴한 가격과 우수한 기계적 특성이 장점이다. 최근, 기존 제작 방식의 단점을 극복하기 위해 적층제조 방식인 선택적 레이저 용융 방법이 보철물 제작에 이용되고 있다. 선택적 레이저 용융 방법의 공정 중 급속 가열과 냉각 과정은 제작된 합금의 미세구조와 결정립을 미세화하고, 기포를 감소시켜 기존 제작 방식에 의한 합금에 비해 기계적 특성을 향상시킨다. 반면, 적층과 급속 가열 및 냉각은 다량의 잔류응력 축적을 초래하는데, 추후 기계적 특성에 악영향을 미칠 수 있다. 따라서, 잔류응력을 제거하기 위해 주로 열처리를 시행하고, 회복과 재결정화에 의한 잔류응력의 감소뿐만 아니라 상변태, 석출물 및 미세구조의 균질화가 동반되어 기계적 특성의 복잡한 변화가 나타난다. 본 문헌고찰에서 코발트-크롬 합금의 제작 방식 비교 및 선택적 레이저 용융 방법으로 제작된 합금의 특징에 대해 알아보고자 한다.

• 대한치과기공학회지
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• 제24권1호
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• pp.33-41
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• 2002

In dental prosthetics, the application of metal-ceramic restorations has steadily increased since their introduction. This is due to excellent esthetics in combination with high mechanical stability. In order to optimum bond strength between metal and ceramics, controlled oxidation of metal substructure is essential factor. Beryllium containing and beryllium free Ni-Cr alloys for metal-ceramic restorations were evaluated for the metal-ceramic bond strength by changing heat treatment for oxide formation. A mechanical three-point bending test was employed to evaluate the interfacial bond strength of metal-ceramic. In each metal, plate type specimens were used for mechanical three-point bending test. With Ni-Cr alloys for metal ceramics, mechanical three-point bending test showed that double degassing was more available preheat treatment method than another. It was found that beryllium containing Ni-Cr alloys are more effective than beryllium-free for metal-ceramic bond strength.

• 대한치과기공학회지
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• 제8권1호
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• pp.51-55
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• 1986

The castability of base metal alloys for dental casting in influenced by burn-out temperature and recent percentage. Burn-out temperatures for casting are set at 200$^{\circ}F$ interval from 1000$^{\circ}F$ to 1800$^{\circ}F$. According to recast metal percent in new cast alloy metal alloys are tested. The results are as followings: 1. In the new alloy(100%), the castability is the most. 2. The burn-out temperature in 1600$\sim$1800$^{\circ}F$, castability of 100% new alloy was more four times than of 50% new alloy plus 50% recast alloy. The using of 50% new alloy and 50% recast alloy, therefore, was unlike in castability. 3. The burn-out temperature in 1600$^{\circ}F$, castability of 100% new alloy was more than four times in soaking 20 minutes, but there was no any difference at 18700$^{\circ}F$. 4. It is investigated that the optimal burn-out temperature is 1600$^{\circ}F$ for the C & B alloy.