Effect of argon ion bombardment on amorphous silicon carbonitride films

Amorphous silicon carbonitride (a-SiCN:H) films were synthesized by radiofrequency (RF) Plasma Enhanced Vapor Chemical Deposition (PECVD) using hexamethyldisilazane (HMDSN) as precursor compound. Then, the films were post-treated by Plasma Immersion Ion Implantation (PIII) in argon atmosphere from 15 to 60 min The hardness of the film enhanced after ion implantation, and the sample treated at 45 min process showed hardness greater than sixfold that of the untreated sample. This result is explained by the crosslinking and densification of the structure Films were exposed to oxygen plasma for determining of the etching rate. It decreased monotonically from 33 angstrom/min to 19 angstrom/min for the range of process time, confirming structural alterations. Hydrophobic character of the a-SiCN:H films were modified immediately after ion bombardment, due to incorporation of polar groups. However, the high wettability of the films acquired by the ion implantation was diminished after aging in air. Therefore, argon PIII made a-SiCN.H films mechanically more resistant and altered their hydrophobic character.

Study of magnetic field enhanced plasma immersion ion implantation in Silicon

A comparison between experimental measurements and numerical calculations of the ion current distribution in plasma immersion ion implantation (PIII) with external magnetic field is presented. Later, Silicon samples were implanted with nitrogen ion to analyze the effect on them. The magnetic field considered is essentially non-uniform and is generated by two magnetic coils installed on vacuum chamber. The presence of both, electric and magnetic field in PIII create a crossed ExB field system, promoting drift velocity of the plasma around the target. The results found shows that magnetized electrons drifting in ExB field provide electron-neutral collision. The efficient ionization increases the plasma density around the target where a magnetic confinement is formed. As result, the ion current density increases, promoting significant changes in the samples surface properties, especially in the surface wettability.

Bonding of facial silicon with nanoparticles to an acrylic resin substrate

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

Laser stimulated piezoelectricity in Er3+ doped GeO2-Bi2O3 glasses containing silicon nanocrystals

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Amorphous silicon carbonitride films modified by plasma immersion ion implantation

Amorphous silicon carbonitride (a-SiCN:H) films were deposited from hexamethyldisilazane (HMDSN) organic compounds via radio-frequency (RF) glow discharges. Afterwards the films were bombarded, from 15 to 60 min, with nitrogen ions using Plasma Immersion Ion Implantation (PIII) technique. X-ray photoelectron spectroscopy (XPS) showed that O-containing groups increased, while C-C and/or C-H groups decreased with treatment time. This result indicates chemical alterations of the polymeric films with the introduction of polar groups on the surface, which changes the surface wettability. In fact, the hydrophobic nature of a-SiCN:H films (contact angle of 100 degrees) was changed by nitrogen ion implantation and, and after aging in atmosphere air, all samples preserved the hydrophilic character (contact angle <80 degrees) independently of treatment time. The exposure of the films to oxygen plasma was performed to evaluate the etching rate, which dropped from 24% to 6% while the implantation time increased from 15 to 60 min. This data suggests that Pill increased the film structure strength, probably due to crosslinking enhancement of polymeric chains. Therefore, the treatment with nitrogen ions via Pill process was effective to modify the wettability and oxidation resistance of a-SiCN:H films. (C) 2014 Elsevier Ltd. All rights reserved.

One-dimensional silicon and germanium nanostructures with no carbon analogues

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

SILICON IN ROW AND NITROGEN IN TOPDRESSING FERTILIZATION ON RICE UNDER DRY LAND AND SPRINKLER IRRIGATION CONDITIONS

The objective of this work was to evaluate the effects of silicon application adjusted with nitrogen fertilization via top-dressing on grain productivity, the silicon contents of the soil, in the plant tissue and nitrogen contents in dry and irrigated conditions. The experimental outlining was from designed blocks with subdivided parcels and four repetitions. The treatments consisted of culture system (dry and irrigated) and the under parcels by the combination of silicon (0 and 100 kg ha(-1)), in magnesium and calcium silicate form (with 23% of SiO2), and four doses of N (urea) via top-dressing (0, 30, 60 and 90 kg ha(-1)). Silicon application at sowing furrow was a viable technique because it provided significant increase in the content of this element in the root growth of rice. The application of silicon in the sowing furrow did not change the content of the element nor the nitrogen nutrition in rice plants. The nitrogen application reduced the silicon content and increased nitrogen nutrition in rice plants. Silicon application at sowing furrow provided no increase in rice grain yield. When there was no water limitation to nitrogen fertilization enhanced linearly on rice grain yield, whereas under water stress the effect of nitrogen fertilization was limited.

Preparação de substratos de carbeto de silício para fins aeroespaciais

This conclusion thesis has the objective of produce substrates of Silicon Carbide from the powder of SiC for aerospace use. The powder of SiC was pressed in cylindrical form by the process called “wet way”. For the inicial pressing process was used a uniaxial squeezer and after that was used a isostatic squeezer, after that the samples were synthesized. The next step was the machining and polishing to improve the features of the surface of the sample. Then the roughness was measured, as also the Arquimedes method and optical microscopy and scanning eletron microscopy. Some innovations were done, in one of the lots little vacancys were done with organic material or silicon to reduce the weight of the sample; and the other innovation were the use of a slip film of SiC on the surface of the sample, that were after synthesized with LASER to reduce the roughness, in this samples the roughness were reduce in 50 % if compared with the other samples

Lixamento do Pinus elliotti com carbeto de silício e óxido de aluminio

The Sanding is a complex process involving many variables that affect the quality of the part produced, working mainly in the timber industry in the production of panels (MDF, MDP, HDF, etc...) and furniture. However, these industries use the sanding process empirically, not optimizing it. The aim of this study was to compare the behavior of sandpaper white aluminum oxide (OA-white) and Black silicon carbide (SiC-black), analyzing variables in the process as: strength, power, emission, vibration, wear particle size of sanding, and its consequences on the surface finish of the workpiece. Made the process of plane grinding samples of Pinus elliottii, processed in parallel to the fibers, which were sanded with sandpaper grain OA white and black 3-SiC abrasive conditions (new, moderately eroded and severely eroded) grain sizes in 3 (80, 100, and 120 mesh). 6 replicates was performed for each condition tested. Each trial was captured output variables of the sanding process: strength, power, emission and vibration. With two stages totaling 108 trials. After the sanded samples, it has the same surface quality by raising the surface roughness Ra. Through experiment, it can be concluded that abrasives OA-white tended to have higher strength, power, emissions and less vibration in the sanding process, compared to the SiC-black. However, surface finish exhibited similar to the particle size of 80 to 100 mesh, worn abrasive conditions. However, the particle size of 120 mesh, obtained by the roughness of sandpaper OA-bank was higher compared to SiC-black to all conditions of sandpaper due to its toughness

Estudo de cerâmicas avançadas para fins de blindagem balística

The research involving new materials has always been considered as a differential in the development of a technology company. This occurred naturally since ancient times, often motivated by reasons of a certain age, where the most common material used was also the name of your time and may be cited as an example the Bronze Age, and later was the Iron. Currently, the use of firearms are they used in resolving conflicts between countries, or a more equivocal, as an instrument of social banditry make innovations in the area of shielding welcome, whether for personal use, in the form of vests or vehicle such as cars, tanks and even aircraft. In this context, is a Silicon Carbide Ceramic, with low density and high hardness. Thus, the aim of this study is the evaluation and comparison of these materials, seeking to improve their properties by means of additives such as boron and silicon metal and amorphous YAG. For this work, the specimens were pre-shaped by means of uniaxial later to be referred for isostatic pressing and sintering. The maximum percentage for each additive was 5%, except for the YAG whose percentage was 8.2% (mass percentage). All compositions were subjected to the same tests (x-ray diffraction, apparent density, optical microscopy, Vickers hardness, scanning electron Microscopita), so that one could draw a comparison between the materials under study, samples that showed better mechanical properties and micro structural, related here by hardness testing and microscopy (optical and SEM) were the silicon carbide doped with YAG and alumina samples, demonstrating the potential of these materials for ballistic protection. Other compositions have high porosity, which is highly undesirable, since in order to harmful influences on the mechanical properties discussed below

Caracterização de cerâmicas a base de nitreto de silício para aplicações estruturais

The need for development of new materials is a natural process in the companies’ technological point of view, seeking improvements in materials and processes. Specifically, among the materials, ceramic exhibit valuable properties, especially the covalent ceramics which have excellent properties for applications which requires the abrasion resistance, hardness, high temperatures, resistence, etc. being a material that has applications in several areas. Most studies are related to improvement of properties, specially fracture toughness that allows the expansion of its application. Among the most promising ceramic materials are silicon nitride (Si3N4) which has excellent properties. The goal of this work was the development and caracterization of Si3N4-based ceramics, doped with yttrium oxide (Y2O3), rar earth concentrate (CTR2O3) and cerium oxide (CeO2) in the same proportion for the evaluation of properties. The powders' mixtures were homogenized, dried and compressed under pressure uniaxial and isostatic. Sintering was carried out in 1850 ⁰C under pressure of 0,1MPa N2 for 1 h with a heating rate of 25 ⁰C / min and cooling in the furnace inertia. The characterizations were performed using Archimedes principle to relative density, weight loss by measuring before and after sintering, phase analysis by X-ray diffraction, microstructure by scanning electron microscope (SEM), hardness and fracture toughness by the method Vickers indentation. The results obtained showed relative density of 97-98%, Vickers hardness 17 to 19 GPa, fracture toughness 5.6 to 6.8 MPa.m1/2, with phases varying from α-SiAlON and β-Si3N4 depending the types of additives used. The results are promising for tribological applications and can be defined according to the types of additives to be used

Endogenous and exogenous teeth whitening through gel-based bleaching hydrogen peroxide (35%) with the aid of silicon guide

The aim of this study is to demonstrate through a case report, a proposed treatment for discolored teeth, with and without pulp vitality, by the technique of external and internal tooth bleaching with hydrogen peroxide to 35% Lase Peroxide Sensy (DMC) using Whitening Lase II Device (DMC), and a silicone guide (3M ESPE) in the palatine portion of the upper teeth. In this clinical case, the patient had darkened dental elements 11 and 22, and dissatisfaction with the coloring of other elements. It was observed that the techniques used and the materials chosen allowed for an excellent aesthetic result, with technical simplicity and low cost, and minimal occurrence of signs and symptoms

Surface morphology and structural modification induced by femtosecond pulses in hydrogenated amorphous silicon films

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

Foliar or soil applications of silicon alleviate water-deficit stress of potato plants

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