Materials Literature
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In this work, a-C:H:Si (DLC-Si) films were produced onto crystalline silicon and polycarbonate substrates by the rf-PACVD technique from gaseous mixtures of CH4 + SiH4 and C2H2 + SiH4. The effects of self-bias and gas composition upon mechanical and optical properties of the films were investigated. Micro-hardness, re…
The sol-gel process is a methodology used to obtain organic-inorganic hybrid solids, which open new possibilities in the field of material science. The sol-gel technique offers a low temperature attractive approach for introducing organic molecules into amorphous materials. In order to introduce tetrakis (2-hydroxy-5-…
In this work, silicon carbide films were deposited onto tungsten carbide from a sintered SiC target on a r.f. magnetron sputtering system. Based on previous results about the influence of r.f. power and argon pressure upon the properties of films deposited on silicon substrates, suitable conditions were chosen to prod…
Thin films of BBT were deposited on silicate and Pt/Ti /SiO2 (111) substrates by spin- coating from the polymeric precursor method (Pechini process). The obtained films were characterized by optical microscopy, X-ray diffraction and atomic force microscopy. The influence of viscosity on the morphology of BBT thin film…
The increasingly widespread use of polymeric insulators in vehicle distributors and transmission systems has led to an ongoing quest for quality and low costs. This quest has, in turn, resulted in improved performance and cost benefits, brought about by the use of new polymeric and composite resins. Occasionally, howe…
We described an automatic diameter control system (ADC), for the laser heated pedestal growth technique, that reduces the diameter fluctuations in oxide fibers grown from unreacted and non-sinterized pedestals, to less than 2% of the average fiber diameter, and diminishes the average diameter fluctuation, over the ent…
Gas sensors based in semiconductor oxides show a change in the resistance when they are exposed to certain gaseous atmospheres. In this paper, the influence on the sensor electrical resistance with the film thickness in vacuum and air are studied. The conduction process is analyzed considering the existence of Schottk…
This paper presents the chemical and physical characterizations of SiO2 and SiO2-CaO bioactive glasses incorporated with samarium atoms, produced by sol-gel synthesis. The objective is to provide biocompatible and biodegradable radioactive seeds as an alternative to be used in Brachytherapy for the treatment of prosta…
Impedance spectroscopy technique was used to investigate the electric properties of Zn7Sb2O12, an electroceramic with inverse spinel type structure. The electric characterization of the Zn7Sb2O12 semiconducting ceramic was performed at temperature from 250 to 550 degreesC, in the frequency range from 5 Hz to 13 MHz. Z…
In this study a coaxial line was used to connect a microwave-frequency Network Analyzer and a base moving sample holder for dielectric characterization of ferroelectric materials in the microwave range. The main innovation of the technique is the introduction of a special sample holder that eliminates the air gap effe…
Experimental investigation and modeling of pulsed H2/CH4 plasmas used for diamond deposition are presented. Two plasma configurations are studied : a 2.45 GHz microwave cavity configuration and a 915 MHz surface-wave configuration. Time-resolved measurements of the gas temperature determined from the Doppler broadenin…
The chemical durability, density and structure of the BABAL glasses with batch compositions (100-x)(0.30BaO·0.50B2O3·0.20Al2O3)·xFe 2O3 (1 < x < 10 mol%), were investigated using Mössbauer spectroscopy, electron paramagnetic resonance (EPR), X-ray diffraction, Raman and differential thermal analysis (DTA). The chemica…
The purpose of this work is to show the correlation between the fractal dimension, D, and mechanical properties such as work of fracture, gammawof, and fracture toughness, K Ic. Alumina-mullite-zirconia composites were characterized by the slit-island method, SIM, to obtain values of D and its fractional part, D*. The…
Nb, Ta and Zr are the favorable non-toxic alloying elements for titanium alloys for biomedical applications. Low rigidity titanium alloys composed of non-toxic elements are getting much attention. The advantage of low rigidity titanium alloy for the healing of bone fracture and the remodeling of bone is successfully p…
Calcium phosphates and bioactive glasses have been used in many biomedical applications for more than 30 years due basically to their bioactive behavior. However, ceramics are too brittle for applications that require high levels of toughness and easy processability. In this work, a biphasic calcium phosphate (BCP) an…
The aim of this study was to analyze the microhardness of two resin-modified glass ionomer cements (Vitremer; Fuji II LC); two polyacid-modified composite resins (Freedom; F2000) and a hybrid composite resin (Prodigy), at different depths from the upper surface. Six hemi-cylinders (3 mm height; 3 mm radius) per tested…
Feasibility of designing composites from carbon nanotubes and nanodiamond clusters is discussed based on atomistic simulations. Depending on nanotube size and morphology, some types of open nanotubes can be chemically connected with different facets of diamond clusters. The geometrical relation between different types…
Doped ceria (CeO2) compounds are fluorite type oxides which show oxide ionic conductivity higher than yttria stabilized zirconia, in oxidizing atmosphere. As a consequence of this, considerable interest has been shown in application of these materials for 'low temperature operation (500–650 °C)' of solid oxide fuel ce…