The influence of grain size coating and shaft angulation of different diamond tips on dental cutting

Objectives: To evaluate the influence of the grain size coating and shaft angulation of ultrasonic and high-speed diamond burs on the dental cutting effectiveness. Materials and Methods: For the grain size evaluation, cavities were prepared on 40 incisors using high-speed (1092 and 1093F KG Sorensen®) and ultrasonic tips (8.2142 and 6.2142-CVDentus®). For the shaft angulation evaluation, cavities were prepared on 40 incisors using uniangulated (T1-CVDentus®) and biangulated (T1-A CVDentus®) ultrasonic tips. The cavities were bisected and examined at 50 magnification. The width and depth of cavities were measured by Leica QWin software. Kruskal-Wallis non-parametric test was used for analysis. Results: The grain size did not affect the cutting effectiveness, but the high-speed burs promoted deeper and wider cavities than the ultrasonic tips. The shaft angulation did not affect the cutting effectiveness; both the angulated and biangulated tips had greater cutting efficiency in dentin than in enamel. Conclusions: Ultrasonic tips promoted more conservative preparations and seemed promising for cavity preparation.

Plasma-polymerized acetylene nanofilms modified by nitrogen ion implantation

Thin films were prepared by plasma enhanced chemical vapour deposition (PECVD) from a mixture of acetylene and argon, and post deposition-treated by plasma immersion ion implantation (PIII). The effect of PIII on the nanofilms properties was evaluated as a function of treatment time. The average thickness and roughness were diminished upon PIII. On the other hand, hardness (0.7-3.9 GPa) and elastic modulus (29-54 GPa) increased upon 60 min of ion bombardment. Such results are ascribed mainly to the densification of the film structure caused by the increment in the crosslinking degree with increasing the energy deposited in the films. Wettability of the samples, investigated by contact angle measurements, was reduced (from 64 to 21°) right after PIII. This result, attributed to the introduction of polar groups in the film structure, was not preserved as the sample was aged in atmosphere. After aging, contact angles were larger than 70° but still smaller than 90°. Although the wettability has decreased with aging, the hydrophilic character of the samples was preserved. For certain treatment times, nitrogen PIII turned the plasma-polymerized acetylene films smoother, denser, mechanically and tribologicaly more resistant than the as-deposited material. © 2013 Elsevier B.V.

Mechanical and tribological properties of a-C:H:F Thin Films

a-C:H films were grown by plasma-enhanced chemical vapor deposition in atmospheres composed by 30 % of acetylene and 70 % of argon. Radiofrequency signal (RF) was supplied to the sample holder to generate the depositing plasmas. Deposition time and pressure were chosen 300 s and 9.5 Pa, respectively, while the excitation power changed from 5 to 125 W. The films were exposed to a post-deposition treatment during 300 s in RF-plasmas (13.56 MHz, 70 W) excited from 13.33 Pa of SF6. Raman and X-ray photoelectron spectroscopy were used to evaluate the microstructure and chemical composition of the films. The thickness was measured by perfilometry. Hardness and friction coefficient were determined from nanoindentation and risk tests, respectively. With increasing power, the film thickness reduced, but a further shrinkage occurred upon the fluorination process. After that, the molecular structure was observed to vary with deposition power. Fluorine was detected in all samples replacing H atoms. Consistently with the elevation in the proportion of C atoms with sp3 hybridization, hardness increased from 2 to 18 GPa. Friction coefficient also increased with power due to the generation of dangling bonds during the fluorination process. © 2012 Springer Science+Business Media, LLC.

Estudo das propriedades de barreira de filmes depositados a plasma sobre a liga de alumínio 2024

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Propriedades de transporte eletrônico em filmes finos policristalinos de diboreto de magnésio (MGB IND.2') analisados pelo modelo de Bloch-Grüneisen

Pós-graduação em Ciência e Tecnologia de Materiais - FC

Adesão bacteriana em braquetes metálicos com tratamento de superfície: estudo in vitro

Pós-graduação em Engenharia Mecânica - FEG

Propriedades mecânicas e tribológicas de filmes sintetizados mediante técnica de deposição e implantação iônica por imersão em plasma

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Filmes orgânicos contendo óxido de alumínio depositados a plasma

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Influência da temperatura e do tipo de substrato em filmes de GaN depositados por magnetron sputtering reativo

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Influência da deposição de filmes de carbono tipo diamante na infiltração bacteriana pela interface entre implantes e pilares protéticos

Pós-graduação em Odontologia Restauradora - ICT

Efeito da implantação iônica por imersão em plasmas sobre a bioatividade de titânio

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

Estudo das propriedades ópticas e vibracionais de filmes de GaN dopados com Mn elaborados por RF Magnetron Sputtering Reativo

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Transport properties of polycrystalline boron doped diamond

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Análise da deposição de filmes finos semicondutores de GaN e GaN e Ga1-xMnxN preparados por sputtering reativo

Thin films of Ga1-xMnxN have great interest in its potential for control of electron spin (spintronics), in most cases this material is synthesized by techniques that have a high degree of control the deposition parameters, such as molecular beam epitaxy (MBE) and deposition of metalorganic chemical vapor deposition (MOCVD). The sputtering technique is an alternative route to produce such materials. Here we study the film deposition Ga1-xMnxN by reactive sputtering technique and apply enhancements such as a glove box, a residual gas analyzer and temperature control system, in order to growth films epitaxially using an analysis of the preconditions of films analyzed by spectroscopic techniques and microscopic. These procedures helped to improve the technique of deposition by cleaning substrates in an inert environment, and by the analysis of trace gases and heating the substrate holder as explained in the literature. Through the applications and comparisons it can be pointed out that the technique has the advantage of its simplicity and relatively low cost compared to MBE and MOCVD, but produces polycrystalline material

Efeito da aplicação de filmes de carbono tipo diamante por plasma no destorque de pilares de implantes com conexões cônicas internas

Pós-graduação em Odontologia Restauradora - ICT