• Korean Journal of Materials Research
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• v.25 no.11
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• pp.636-641
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• 2015

Titanium has many special characteristics such as specific high strength, low elastic modulus, excellent corrosion and oxidation resistance, etc. Beta titanium alloys, because of their good formability and strength, are used for jet engines, and as turbine blades in the automobile and aerospace industries. Low cost beta titanium alloys were developed to take economic advantage of the use of low-cost beta stabilizers such as Mo, Fe, and Cr. Generally, adding a trace of boron leads to grain refinement in casted titanium alloys due to the pinning effect of the TiB phases. This study analyzed and evaluated the microstructural and mechanical properties after plastic deformation and heat treatment in boron-modified Ti-2Al-9.2Mo-2Fe alloy. The results indicate that a trace of boron addition made grains finer; this refinement effect was found to be maintained after subsequent processes such as hot forging and solution treatment. This can effectively reduce the number of required manufacturing process steps and lead to savings in the overall cost as well as low-cost beta elements.

• Corrosion Science and Technology
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• v.3 no.4
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• pp.140-147
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• 2004

High temperature oxidation of Fe-19Cr and Fe-19Cr-0.2Ti alloys is studied at 1173-1373 K in 16.5 kPa $O_2$ - balances $N_2$ atmosphere aimed at clarifying the effect of titanium addition. Oxidation rate of Fe-19Cr alloy was accelerated with titanium. For both alloys chromium rich $(Fe,\;Cr)_2O_3$ was formed as a major oxidation product. On Fe-19Cr-0.2Ti alloy, a thin layer composed of spinel type oxide and titanium oxide was also formed and an internal oxidation of titanium was observed. Titanium was concentrated at the oxide surface and internal oxidation zone but a small amount of titanium was also found in the intermediate corundum type $(Fe,\;Cr)_2O_3$ layer. Crystals of corundum type $(Fe,\;Cr)_2O_3$ formed on Fe-19Cr alloy are coarse but that formed on Fe-19Cr -0.2Ti alloys were fine and columnar. Reason for the difference in oxidation kinetics and crystal structure will be discussed relating to the distribution of aliovalent titanium in corundum type $(Fe,\;Cr)_2O_3$ oxide layer.

• The Journal of Korean Academy of Prosthodontics
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• v.39 no.3
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• pp.297-305
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• 2001

Statement of problem. There have been previous studies about instability according to screw material by means of calculating preload in tightening screw or recording of the torque necessary to loosen screw after tightening screw. Purpose. The purpose of this study was to evaluate screw joint stability through the analysis of fitness at the mating thread surfaces between implant and screw after tightening screws made of different materials. Material and methods. In this study, screws were respectively used to secure a cemented abutment to a hexlock implant fixture; teflon coated titanium alloy screw and titanium alloy screw(Steri-Oss), gold-plated gold-palladium alloy screw and titanium alloy screw(Implant Innovation), gold screw and titanium screw(AVANA Dental Implant System). Each abutment screw was secured to the implant with recommended torque value using a digital torque controller. Each screw was again tightened after 10minutes. All samples were cross sectioned with sandpaper and polished. Then samples were evaluated with an scanning electron microscope analysis. Results. In titanium alloy screw, irregular contact and relatively large gap was present at mating thread surface. Also in teflon-coated titanium screw, incomplete seating and only partially contact was present at the mating thread surface. In gold-plated gold-palladium alloy screw, relatively close and tight contact without the presence of large gap was present by existing of gold coating at the mating thread surfaces. In gold alloy screw, relatively small gap between the mating components was seen. Conclusions. This result suggested that gold plated gold-palladium alloy screw and gold alloy screw achieved a greater degree of contact at the mating thread surfaces compared to titanium alloy screw and teflon-coated titanium alloy screw.

• Journal of Periodontal and Implant Science
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• v.30 no.4
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• pp.821-836
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• 2000

The Peri-implantitis causes inflammation of periodontal tissue and bone loss. It contaminates surface of implants. Therefore, guided bone regeneration has been used for the treatment of this disease. For the reosseointegration of the exposed surface, various mechanical and chemical methods have been used for cleaning and detoxication of implant surface. Among these methods, air-powder abrasive and oversaturated citrate are known to be most effective. However, these treatments may deform implant surface. In this research, changes of surface roughness they were examined. 10 experimental machined titanium cylinder models were fabricated to be used for control groups. Each of them was air powder abraded for 1 minute and they were named group 1. And then, group 1 were burnished with cotton pellets soaked with citrate for 30 seconds(Group 2), 1 minute(Group 3), 3 minutes(Group 4), and 5 minutes(Group 5) burnishing were applied for grouping respectively. Each group were examined with SPM, and their surface roughness were measured and analyzed. 1. Surface roughness of titanium decreased when it was air-powder abraded for 1 minute. It was statistically significant. 2. When Air-powder abraded titanium were treated with citrate for 3 minutes, Their surface roughness was the lowest. Titanium treated for 1 minute was the second lowest and 30 seconds was the third and titanium burnished for 5 minutes was the highest. 3. Surface roughness of titanium which was treated with citrate was decreased till 3 minutes, which was statistically significant. There was no statistical significance from 30 seconds to 1 minute and from 1 minute to 3 minutes, and there was statistical significance from 30 seconds to 3 minutes. 4. Oxide layer was formed when titanium is exposed to air, and it was removed when air-powder abraded. It was made when treated with citrate. It is thought that citrate treatment is necessary after the air-powder abrasion, and 1 minute is clinically and qualitatively adequate for burnishing time of citrate.

• The Journal of Korean Academy of Prosthodontics
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• v.45 no.6
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• pp.795-804
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• 2007

Statement of problem. Nano-scale calcium-phosphate coating on the anodizing titanium surface using ion beam-assisted deposition (IBAD) has been recently introduced to improve the early osseointegration. However, not much is known about their surface characteristics that have influence on tissue-implant interaction. Purpose. This study was aimed to investigate microtopography, surface roughness, surface composition, and wettability of the titanium surface modified by the anodic oxidation and calcium phosphate coating using IBAD. Material and methods. Commercially pure titanium disks were used as substrates. The experiment was composed of four groups. Group MA surfaces represented machined surface. Group AN was anodized surface. Group CaP/AN was anodic oxidized and calcium phosphate coated surfaces. Group SLA surfaces were sandblasted and acid etched surfaces. The prepared titanium discs were examined as follows. The surface morphology of the discs was examined using SEM. The surface roughness was measured by a confocal laser scanning microscope. Phase components were analyzed using thin-film x-ray diffraction. Wettability analyses were performed by contact angle measurement with distilled water, formamide, bromonaphtalene and surface free energy calculation. Results. (1) The four groups showed specific microtopography respectively. Anodized and calcium phosphate coated specimens showed multiple micropores and tiny homogeneously distributed crystalline particles. (2) The order of surface roughness values were, from the lowest to the highest, machined group, anodized group, anodized and calcium phosphate deposited group, and sandblasted and acid etched group. (3) Anodized and calcium phosphate deposited group was found to have titanium and titanium anatase oxides and exhibited calcium phosphorous crystalline structures. (4) Surface wettability was increased in the order of calcium phosphate deposited group, machined group, anodized group, sandblasted and acid etched group. Conclusion. After ion beam-assisted deposition on anodized titanium, the microporous structure remained on the surface and many small calcium phosphorous crystals were formed on the porous surface. Nanoscale calcium phosphorous deposition induced roughness on the microporous surface but hydrophobicity was increased.

• Journal of International Society for Simulation Surgery
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• v.1 no.2
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• pp.99-102
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• 2014

The skull defect can be made after the trauma, oncologic problems or neurosurgery. The skull reconstruction has been the challenging issue in craniofacial fields for a long time. So far the skull reconstruction with autogenous bone would be the standard. Although the autogenous bone would be the ideal one for skull reconstruction, donor site morbidity would be the inevitable problem in many cases. Meanwhile various types of allogenic and alloplastic materials have been also used. However, skull reconstruction with many alloplastic material have produced no less complications including infection, exposure, and delayed wound healing. Because the 3D printing technique evolved so fast that 3D printed titanium implant were possible recently. The aim of this trial is to try to restore the original skull anatomy as possible using the 3D printed titanium implant, based on the mirrored three dimensional CT images based on the computer simulation. Preoperative computed tomography (CT) data were processed for the patient and a rapid prototyping (RP) model was produced. At the same time, the uninjured side was mirrored and superimposed onto the traumatized side, to create a mirror-image of the RP model. And we fabricated Titanium implant to reconstruct three-dimensional orbital structure in advance, using the 3D printer. This prefabricated Titanium-implant was then inserted onto the defected skull and fixed. Three dimensional printing technique of titanium material based on the computer simulation turned out to be very successful in this patient. Individualized approach for each patient could be an ideal way to manage the traumatic patients in near future.

• Journal of Dental Rehabilitation and Applied Science
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• v.27 no.2
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• pp.223-231
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• 2011

The purpose of this case report is to introduce new attachment system(milled titanium bar with $Locator^{(R)}$ attachment) for implant supported overdenture in maxillary edentulous patients. A 56-years-old male patient visited the hospital due to the mobility of his maxillary fixed partial dentures(10-unit bridge). Including temporomandibular joint(TMJ), there was no specific PMHs to influence dental treatment. In radiographic and clinical evaluation, there was a severe bone resorption and mobility in maxillary teeth. Accordingly all the remaining maxillary teeth was extracted and fabrication of implant supported overdenture was planned. The milled titanium bar with $Locator^{(R)}$ was designed as an attachment system, considering the stability and retention of denture, masticatory efficiency, oral hygiene care, esthetics, pronunciation, and patient's financial state. The milled titanium bar was manufactured using CAD/CAM technology, and $Locator^{(R)}$ attachment connected to the bar by tap & drill method. For over 1-year, in terms of function and esthetics, satisfactory result was obtained.

• Resources Recycling
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• v.16 no.4
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• pp.33-39
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• 2007

Titanium scrap was re-melted and refined by using a DC-ESR (Direct Current Electro Slag Remelting) apparatus. A graphite rod was used as an anode. The used slag was $CaF_2-TiO_2-CaO$ slag system. The effect of slag composition on the shape and oxygen content of re-melted ingot was studied. The titanium ingot was produced very well from the $CaF_2-TiO_2$ slag system, and the oxygen content of the ingot was less than that of titanium scrap. The addition of CaO into $CaF_2-TiO_2$ slag system made the bad shape of titanium ingot. The oxygen content of the ingot was also higher than that of titanium scrap.

• Journal of Welding and Joining
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• v.27 no.6
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• pp.68-73
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• 2009

Recently, as titanium and titanium alloys are being increasingly used in wide areas, there are on-going researches to obtain high quality weld zone. In particular, growing interest is being drawn to laser welding, which involves low heat input and large aspect ratio in various welding processes and can facilitate shield in atmospheric condition compared with electron beam welding. The first report covered the analysis of embrittlement by the bead color of weld zone through quantitative analysis of oxygen and nitrogen and measurement of hardness as basic experiment to apply laser welding to titanium. Results indicated that the element that affect embrittlement the most was nitrogen, and as embrittlement and oxygenation go on, bead color changed to silver, gold, brown, blue and gray. This study performed butt welding of pure titanium and STS304 by using 1kW CW Nd:YAG laser, and to find out basic physical properties, evaluated welding performance by laser output, welding speed, root gap and misalignment etc, and examined mechanical properties through tensile stress and Erichsen test. The reason particles of pure titanium welded metal and HAZ are greater than STS304 is because they are pure metal and do not include many impure elements that work as nuclei in case of resolidification, thus becoming coarse columnar crystals eventually. In addition, the reason STS304 requires more energy during welding than pure titanium is because the particle size of base metal is smaller.

• Journal of Periodontal and Implant Science
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• v.49 no.3
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• pp.193-204
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• 2019

Purpose: The reaction of cells to a titanium implant depends on the surface characteristics of the implant which are affected by decontamination. The aim of this study was to evaluate the cytocompatibility of titanium disks treated with various decontamination methods, using salivary bacterial contamination with dental pellicle formation as an in vitro model. Methods: Sand-blasted and acid-etched (SA) titanium disks were used. Three control groups (pristine SA disks [SA group]; salivary pellicle-coated SA disks [pellicle group]; and biofilm-coated, untreated SA disks [NT group]) were not subjected to any decontamination treatments. Decontamination of the biofilm-coated disks was performed by 14 methods, including ultrasonic instruments, rotating instruments, an air-powder abrasive system, a laser, and chemical agents. MG63 cells were cultured in the presence of the treated disks. Cell proliferation assays were performed on days 2 and 5 of cell culture, and cell morphology was analyzed by immunofluorescence and scanning electron microscopy (SEM). A vascular endothelial growth factor (VEGF) assay was performed on day 5 of culture. Results: The cell proliferation assay revealed that all decontaminated disks, except for the 2 groups treated using a plastic tip, showed significantly less cell proliferation than the SA group. The immunofluorescence and SEM analyses revealed that most groups showed comparable cell density, with the exception of the NT group, in which the cell density was lower and bacterial residue was observed. Furthermore, the cells grown with tetracycline-treated titanium disks showed significantly lower VEGF production than those in the SA group. Conclusions: None of the decontamination methods resulted in cytocompatibility similar to that of pristine SA titanium. However, many methods caused improvement in the biocompatibility of the titanium disks in comparison with the biofilm-coated, untreated titanium disks. This suggests that decontamination is indispensable for the treatment of peri-implantitis, even if the original biocompatibility cannot be restored.