Application of pulsed Nd:YAG laser in thin foil microwelding

Experimental investigations were carried out using a Nd:YAG laser operating in pulsed mode for welding a lap joint between thin foil and thick sheet. The pulse energy was varied from 1.5 to 3.0 J at increments of 0.25 J with a 4 ms pulse duration. The base material used for this study was AISI 316L foils with 100 mu m thickness and sheet with 3.0 mm thickness. The welds were analysed by optical and electronic microscopy, tensile shear tests and micro hardness. The results indicate that pulse energy control is of considerable importance to join thin foil and thick sheet with good quality. The ultimate tensile strength of the welded joints increased at first and then decreased as the pulse energy increased. The process appeared to be very sensitive to the gap between couples. Large voids delimited by the molten zone boundary were observed in joints welded with high pulse energy.

Effects of laser beam energy on the pulsed Nd:YAG laser welding of thin sheet corrosion resistant materials

The aim of this study was to value the possibility to join, for pulsed Nd:YAG laser welding, thin foils lap joints for sealing components in corrosive environment. Experimental investigations were carried out using a pulsed neodymium: yttrium aluminum garnet laser weld to examine the influence of the pulse energy in the characteristics of the weld fillet. The pulse energy was varied from 1.0 to 2.5 J at increments of 0.25 J with a 4 ms pulse duration. The base materials used for this study were AISI 316L stainless steel and Ni-based alloys foils with 100 mu m thickness. The welds were analyzed by electronic and optical microscopy, tensile shear tests and micro hardness. The results indicate that pulse energy control is of considerable importance to thin foil weld quality because it can generate good mechanical properties and reduce discontinuities in weld joints. The ultimate tensile strength of the welded joints increased at first and then decreased as the pulse energy increased. In all the specimens, fracture occurred in the top foil heat-affected zone next to the fusion line. The microhardness was almost uniform across the parent metal, HAZ and weld metal. A slight increase in the fusion zone and heat-affected zone compared to those measured in the base metal was observed. This is related to the microstructural refinement in the fusion zone, induced by rapid cooling of the laser welding. The process appeared to be very sensitive to the gap between couples.

Influência da potência de laser Nd: YAG na soldagem do aço inoxidável duplex UNS S32205

Pós-graduação em Engenharia Mecânica - FEIS

Avaliação do tipo de carregamento, pela análise de elementos finitos, sobre a resistência de união ao cisalhamento da interface metal/porcelana (Ni-Cr/vita omega 900)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Efeito de três sistemas de osteotomia - ultrassom cirúrgico, laser Er, Cr: YSGG e sistema rotatório - sobre o processo de osseointegração e reparo de defeitos ósseos em tíbia de ratos: estudo histomorfométrico, imuno-histoquímico e biomecânico

Pós-graduação em Odontologia - FOAR

Efeito do laser Nd:Yag no pré-tratamento dentinário e selamento marginal, em restaurações de cimento de ionômero de vidro resina modificado

Pós-graduação em Odontologia Restauradora - ICT

Corrosion properties of Fe-Cr-Nb-B amorphous alloys and coatings

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Evaluation of Decomposition Procedure to Determine Ba, Co, Cr, Cu, Ni, Mn, V, and Zn Total Content in Soil Samples

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Efeito do tratamento da superfície dental com os lasers Nd:YAG e Er: Yag na adesão da resina composta à dentina recém clareada

To evaluate the effect of surface treatment with Er:YAG and Nd:YAG laser on resin composite bond strength to recently bleached dentin. Material and Methods: In this study 120 bovine incisors were used and distributed into two groups: Group C: without bleaching treatment; Group B: with bleaching treatment (35% hydrogen peroxide). Each group was divided into three subgroups: Subgroup N: without laser treatment; Subgroup Nd: irradiation with Nd:YAG laser; Subgroup Er: irradiation with Er:YAG laser. Next, the adhesive system (Adper Single Bond 2) was applied and composite buildups were constructed with Z350 composite. The teeth were sectioned to obtain dentin-resin sticks (1x1mm) and analyzed by microtensile bond testing. The data were statistically analyzed by the ANOVA and Tukey tests. Results: The results showed that the bond strength values in the bleached control group (16.17 MPa) presented no significant difference in comparison with the group bleached and irradiated with Er:YAG laser (14.69 MPa). The non bleached control group (26.79 MPa) presented significant difference in bond strength when compared with the non bleached group irradiated with Er:YAG laser (22.82 MPa) and with the group treated by bleaching and irradiation with Nd:YAG laser (28,792 MPa). The group without bleaching treatment and irradiated with Nd:YAG (36.1 MPa) presented a significant increase in bond strength in comparison with the other groups. Conclusion: The use of Nd:YAG laser on bleached specimens was able of completely reversing the immediate effects of bleaching, obtaining bond strength values similar to those of the control group

Ocorrência de opacidade de cápsula posterior em cães pós-facoemulsificação, com ou sem a utilização de lente intraocular dobrável e efeitos do Nd: Yag Laser

Pós-graduação em Cirurgia Veterinária - FCAV

Implantes nanotopograficamente modificados pela ação do laser Yb-YAG

Titanium has proven its suitability as an implant material in surgery over many years. Excellent biocompatibility and corrosion resistance are outstanding features. Implant surfaces always causes concern and interest in scientific communities, due to its close relationship with the time required for osseointegration. Surface modification can be performed by several methods, being laser irradiation one of them. Titanium implants with two different surfaces were inserted in rabbits: Group I (G-I: machined surface, control group), and group II (G-II: laser irradiated, test group) being processed 30 and 60 days after surgery for histological analysis. Surface characterization was performed with SEM-EDS, contact angle measurement, and mean roughness (Ra) parameters. Surface analysis in the GII group showed a nanomorphology affected by melt and quick solidification zones following laser irradiation (SEM), as well as total wettability and Ra mean values significantly higher than in the G-I group. The laser treatment resulted in a homogenized, porous surface, with increased surface area and volume. Histological analysis of bone-implant contact linear extension (BIC) showed better results in G-II at 30 days (39.26 ± 18.23 and 68.41 ± 13.68 for G-I and G-II groups, respectively). Titanium implants modified by laser irradiation showed important features that may accelerate early osseointegration.

Avaliação dos efeitos do laser Er,Cr:YSGG em defeitos ósseos críticos e no tratamento de doença periodontal induzida em ratos submetidos a inalção de fumaça de cigarro

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effect of Er,Cr:YSGG laser application in the treatment of experimental periodontitis

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Treatment of periodontal disease with an Er,Cr:YSGG laser in rats exposed to cigarette smoke inhalation

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Aplicação do laser Er,Cr:YSGG em periodontia e implantodontia: revisão de literatura

Lasers are widely used tools in many therapeutic modalities in medical lasers and can be divided into low and high intensity. For the treatment of periodontal disease, lowintensity lasers are related to reduce the number of bacteria and to induce inflammatory and analgesic properties. The high intensity lasers can be used in surgical procedures, improving hemostasis, promoting more accurate cuts, removal of dental calculus as well as thermomechanical and photochemical interactions with tissue. The high-intensity laser Erbium impregnated with chromium: YSGG laser has shown satisfactory results when applied in endodontic, restorative denstistry, surgical procedures and non-surgical periodontal treatment. The purpose of this review is to evaluate the studies that investigated the effects of Er, Cr: YSGG laser on the morphology and biocompatibility of titanium and root surfaces irradiated with these lasers, even beyond the effect on the treatment of periodontitis and periimplantitis.