Penetration depth into dental casting alloys by Nd:YAG laser

Baba, Naoki; Watanabe, Ikuya

doi:10.1002/jbm.b.30117

Cited by 58 publications

(83 citation statements)

References 11 publications

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“…Laser surface treatment was performed using a dental Nd:YAG laser welding machine (Neolaser L, Girrbach Dental Systems, Pforzheim, Germany) using the following parameters: spot diameter of 1.4 mm, pulse duration of 10 ms and emission voltages of 240 V or 300 V [16]. During the laser treatment, argon gas shielding was applied from two nozzles set at a 45° angle on both sides above the treatment area of the specimen.…”

Section: Laser Surface Treatmentmentioning

confidence: 99%

Microstructure and mechanical properties of surface treated cast titanium with Nd:YAG laser

Poulon-Quintin¹,

Watanabe²,

Watanabe³

et al. 2012

Dental Materials

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Objective: To investigate the effect of laser surface treatment of cast titanium alloy on microstructure and mechanical properties.Methods: Dumbbell-and plate-shaped cast titanium specimens were prepared for mechanical testing and microstructure analysis. After the cast surfaces of each specimen were laser-treated using a dental Nd:YAG laser machine at 240 V and 300 V with and without argon gas shielding, tensile testing and microstructure analysis were conducted.Hardness depth profiles were also made from the cross-section of laser-treated cast specimens. Microstructural and chemical analysis were performed by means of the SEM, XRD, AES and WDS.Results: The results of tensile testing and Vickers hardness depth profiling showed that laser treatment improved the mechanical properties. Bulk microstructure of as-cast titanium was mainly composed of α-grains with acicular and widmanstatten patterns.The laser melted zone was characterized by columnar beta grains. When the emission voltage of laser increased to 300 V, a larger grain size was promoted. The XRD analysis indicated that the beta phase formation was clearly noticeable after laser surface treatment. Supplementary marked peaks of the TiO, TiO 2 and Ti 2 N were detected without argon gas shielding. When argon shielding gas was used, the presence of titanium oxide was significantly reduced and the peaks of titanium nitride disappeared.Significance: Laser treatment on cast titanium surfaces showed significant enhancement of mechanical properties and modification of microstructures, and therefore could produce reliable titanium metal frameworks for dental prostheses.3

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Section: Laser Surface Treatmentmentioning

confidence: 99%

Microstructure and mechanical properties of surface treated cast titanium with Nd:YAG laser

Poulon-Quintin¹,

Watanabe²,

Watanabe³

et al. 2012

Dental Materials

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“…This appearance suggests inadequate beam penetration 9,17) . According to some authors, the laser beam penetrates to a limited depth of 1.5 mm 19,23,28,29) . Thus, it is probable that the laser beam does not reach the center of the 3.5 mm specimens, as can be seen in Fig.…”

Section: Discussionmentioning

confidence: 99%

“…They annealed the specimens, homogenizing the grain structure and relieving internal stress. Some authors have reported that residual internal stress may be associated with the occurrence of internal flows in welded titanium 29) . Therefore, the residual internal stress could have modified the weldability of CP-Ti.…”

Section: Discussionmentioning

confidence: 99%

“…As such, the diameter of the welding spot will be larger if a longer pulse duration is used 8,29,30) . When the power of the laser welding is exceeded and the laser energy supply is prolonged, the temperature of the molten metal exceeds the boiling point and causes the molten metal to evaporate 29) . The increase in the volume of evaporated metal compared with that of molten metal results in high pressure.…”

Section: Discussionmentioning

confidence: 99%

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Fatigue performance of joints executed in pure titanium structures with several diameters

Nuñez-Pantoja¹,

Vaz

Nóbilo³

et al. 2011

Dent. Mater. J.

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This study evaluated fatigue strength of CP-Ti laser-welded joints. Sixty (20/diameter) CP-Ti casted dumbbell rods with diameters of 1.5, 2.0, and 3.5 mm were sectioned and welded using two joint openings (0.0 (00) and 0.6 mm (06)). Six groups were formed, amounting to a total of 9 (n=10) with inclusion of intact groups. Welding was executed using 360 V/8 ms (1.5 and 2.0 mm) and 380 V/9 ms (3.5 mm). Joints were finished, polished, and submitted to radiographic examination to visually analyze presence of porosity (PP). Specimens were submitted to cyclic tests, and the number of cycles until failure (NC) was recorded. Fractured surfaces were examined by SEM. Kruskal-Wallis and Dunn (=0.05) tests demonstrated that NC was lower for all diameters with 06, and for 3.5 mm/00. NC and PP were found to have a negative correlation (Spearman Coefficient). For CP-Ti frameworks with thin diameters, laser welding is better when structures are juxtaposed.

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“…It is evident that there is no agreement among the abovementioned studies owing to different welding parameters used, which then resulted in discrepancies of the weld metal structure and consequent changes in the mechanical properties of the weld metal. Therefore, Baba and Watanabe 7) reported that for an optimal thickness of a dental metal, it was important that suitable conditions for laser welding be selected to obtain sufficient penetration depth when welding prostheses. On this note, Liu et al 8) found that the penetration depth of laser-welded Ti was proportional to the output current.…”

Section: Introductionmentioning

confidence: 99%

Fracture Resistance of Nd:YAG Laser-welded Cast Titanium Joints with Various Clinical Thicknesses and Welding Pulse Energies

Lin

Lin²,

Wang³

et al. 2007

Dent. Mater. J.

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The purpose of this study was to evaluate the fracture resistance of Nd:YAG laser-welded cast titanium (Ti) joints with various clinical thicknesses and welding pulse energies. A four-point bending test was used to assess the effects of various specimen thicknesses (1-3 mm) and welding pulse energies (11-24 J) on the fracture resistance of Nd:YAG laser-welded Ti dental joints. Fracture resistance was evaluated in terms of the ratio of the number of fractured specimens to the number of tested specimens. As for the fracture frequencies, they were compared using the Cochran-Mantel-Haenszel test. Morphology of the fractured Ti joints was observed using a scanning electron microscope. Results showed that decreasing the specimen thickness and/or increasing the welding pulse energy, i.e., increasing the welded area percentage, resulted in an increase in the fracture resistance of the Ti joint. Where fracture occurred, the fracture site would be at the center of the weld metal.

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Penetration depth into dental casting alloys by Nd:YAG laser

Cited by 58 publications

References 11 publications

Microstructure and mechanical properties of surface treated cast titanium with Nd:YAG laser

Microstructure and mechanical properties of surface treated cast titanium with Nd:YAG laser

Fatigue performance of joints executed in pure titanium structures with several diameters

Fracture Resistance of Nd:YAG Laser-welded Cast Titanium Joints with Various Clinical Thicknesses and Welding Pulse Energies

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