In the present work, we have studied the effect of the piezoelectricity of elastically deformed cortical bone collagen on surface using a biomimetic approach. The mineralization process induced as a consequence of the piezoelectricity effect was evaluated using scanning electron microscopy (SEM), thermally stimulated depolarization current (TSDC), and differential scanning calorimetry (DSC). SEM micrographs showed that mineralization occurred predominantly over the compressed side of bone collagen, due to the effect of piezoelectricity, when the sample was immersed in the simulated body fluid (SBF) in a cell-free system. The TSDC method was used to examine the complex collagen dielectric response. The dielectric spectra of deformed and undeformed collagen samples with different hydration levels were compared and correlated with the mineralization process followed by SEM. The dielectric measurements showed that the mineralization induced significant changes in the dielectric spectra of the deformed sample. DSC and TSDC results demonstrated a reduction of the collagen glass transition as the mineralization process advanced. The combined use of SEM, TSDC, and DSC showed that, even without osteoblasts present, the piezoelectric dipoles produced by deformed collagen can produce the precipitation of hydroxyapatite by electrochemical means, without a catalytic converter as occurs in classical biomimetic deposition.

Unprinted, unsized, and sized security papers (SP) were treated under SiCI4-, 02-, and CF,-cold plasma conditions. The plasma treatments were carried out in a stainless steel, parallel plate RF (30 kHz) reactor. The influence of plasma parameters, such as RF power, pressure, and treatment time, on the surface properties of plasma-modified security paper was examined. The newly gained surface characteristics were evaluated by Wilhelmy wettability measurements, x-ray photoelectron spectroscopy (ESCA), and scanning electron microscopy (SEM). Statistical experimental designs were used to understand the interactive effects of the plasma parameters. It was found that short treatment times and low RF power values produced the highest wettability with both SiC1, and O2 plasmas regardless of the sizing. Printing and durability characteristics of the plasma-treated substrates were equivalent or superior to the standard samples. Mechanisms of plasma-induced surface modifications are discussed for the paper substrates.

The interest in hardmetals as tool materials is known from some decades ago. However, the demand for improvement in mechanical fatigue, wear and corrosion properties is asking for submicron, ultrafine and nano-structured materials. In order to have a good mechanical propertiesmicrostructure correlation it is important to get a statistically acceptable result but, the complex microstructures obtained in these materials, mostly based on admixed sintered carbides, borides and carbonitrides, restricts such type of studies to the materials development research stage. New analytical techniques such as Electron Backscattering Diffraction (EBSD) coupled to SEM-EDX systems allows crystallographic and chemical evaluation of this fine microstructures in bulk samples.This work comprises the microstructure evaluation of carbide-based hard metals by SEM-EDX-EBSD and HRTEM complemented with XRD. Samples were prepared from pressureless vacuum sintered admixed WC, VC, TiC and Co sub-micron powders. Special care in the SEM bulk samples preparation for EBSD studies was taken in order to minimize the deformed surface layer. Previous works have recommended the use of ion polishing post mechanical polishing; however, the low quantity of "No solution" in the identification of patterns in the Euler angle maps implies an unstrained surface.The phases crystallographic orientation maps in Fig. 1 show relevant microstructural parameters for sintered materials such as the high binder mean free path depicted by the Co phase distribution map, high connectivity or contiguity of the sub-micron WC phase and a high crystallographic misorientation existing in all three phases which is typical of sintered materials. On the other hand, individual phases grain size evaluation is more reliable than estimating it from either SE or BSE images. Phases with different chemistry as the (CoW)C or (WV)C might result with a similar gray level depending on the elemental atomic ratios. Figure 2 combines the different phases Euler angle maps overlapping with diffraction patterns for WC and (W,V) x C 1-x . Due to the inexistence of ICDD data for the latter phase it has been used such of the WC for identification resulting in a good fit. It elucidates that V has a small influence on the WC crystal structure when entering in solution.

ResumoSe desarrollaron materiales compuestos de matriz polimérica para toberas en cohetes; con dos zonas: una térmica para soportar elevadas temperaturas de combustión y una estructural que resista los esfuerzos generados. La zona térmica se elaboró con materiales de comportamiento ablativo, probados a temperaturas de hasta 2950°C durante dos minutos, los cuales fueron reforzados con polvo cerámico y/o subproducto de la industria siderúrgica (cerámico 2). Con base en los resultados obtenidos del comportamiento de térmico y de conductividad térmica del material ablativo, se construyó la zona estructural en materiales compuestos fibroreforzados (vidrio y carbono) con matriz polimérica. Los moldes se diseñaron en SolidWorks y se fabricaron por prototipado en ABS rápido y se elaboraron machos disgregables en poliuretano. En la zona térmica se usó un procedimiento de vaciado con vibración con diferentes tipos de matrices (poliéster, vinilester, caucho silicona) y de laminación para la zona estructural. Se evaluó el desempeño mediante simulación de las condiciones reales de operación mediante llama de oxicorte y quemador de ACPM, observando el efecto en la pérdida de peso, espesor, diferencial de temperatura, cambio de propiedades mecánicas, etc.; encontrándose un positivo comportamiento del sistema con matriz de resina vinilester reforzado con polvo cerámico 1 y buenos resultados con cerámico 2, así como una estabilidad en la zona estructural construida con fibras de vidrio y carbono. Substituir todo o texto de orientação deste Template pelo conteúdo de seu trabalho. Inserir o texto com no máximo 1.500 caracteres (200 palavras), sem uso de parágrafos. Deve conter, de maneira concisa, o objetivo, a metodologia, os resultados e as conclusões do trabalho. Palavras-chave: Tobera para cohete; Materiales compuestos particulados; Materiales compuestos fibro-reforzados; Material compuesto ablativo. ROCKET NOZZLE DEVELOPMENT IN ABLATIVE MATERIAL POLYMER MATRIX STRUCTURALLY REINFORCED WITH FIBRE GLASS AND CARBON AbstractPolymer matrix composites for rocket nozzles developed; two areas: Thermal for high combustion temperatures and external structure to withstand the stresses generated. The thermal zone ablative materials behavior, tested at temperatures up to 2950 ° C for two minutes, reinforced ceramic powder and / or dust-product of the steel industry (ceramic 2). Based on the results of the behavior of thermal conductivity and thermal ablative material the structural zone built in fiber-reinforced composite materials (glass and carbon) with polymeric matrix. The molds were designed in SolidWorks and fabricated by rapid prototyping ABS, disintegrating males were manufactured in polyurethane. In the thermal zone emptying procedure vibration with different matrices (polyester, vinylester, silicone rubber) and rolling for the structural zone was used. Performance by simulating real operating conditions was assessed using oxyfuel flame and burner ACPM, loss of weight, thickness, temperature differential change of mechanical prope...

The Fe-Ni-Ag system is of particular interest for its potential applications as soft magnetic granular alloys formed by small magnetic grains embedded in a non-magnetic metal matrix. It is formed by two binary immiscible systems under equilibrium conditions : Fe-Ag and Ni-Ag and one binary system Fe-Ni. These materials are particular important for magnetoresistive properties [1]. The properties of these alloys are closely related to their microstructure, therefore a detailed study of the transformations occurring during milling was undertaken considering materials pre-alloyed with several concentrations of Fe and Ni and then further alloyed with different Ag content. Heat treatments of the mechanically alloyed powders were performed and structural characterization of the sintered powders was carried out.Elemental high purity (99.99%) Fe, Ni and Ag powders with an average particle size of 4.5, 1.2 and 1.3 µm respectively, were blended in a WAV turbula for 2h. The compositions were Fe 30, 50 and 70 at.%, Ni 70, 50 and 30 at% and Ag in balancing concentration to give alloys compositions of (Fe x -Ni 100-x ) y -Ag 100-2y (x= 30, 50, 70 and y=5,20,60). The powders of Fe and Ni were mechanically alloyed under nitrogen atmosphere in a high energy mill SPEX 8000, using hardened steel vials and balls with a ball-to-powder weight ratio of 8:1 and milling periods of 1, 5, 10, 25 to followed the formation of the Fe x Ni y compound. And then further milled with Ag was carried out for 10 h. The powders from the different milling periods and compositions were pressed at 350 MPa and sintered in a graphite crucible at 900ºC for 40 min in argon atmosphere. The products were characterized by optical microscopy, x-ray diffraction (XRD) using a Siemens 5005 diffractometer with Cu-K α radiation (Ni filter) operating at 40 keV and 20 mA. Scanning electron microscopy (SEM) analysis was performed in a Phillips XL30 attached with an EDX DX4 and a EBSD system. Transmission electron microscopy (TEM) was carried out in a Phillips CM10. Samples for TEM were cut by ultramicrotomy techniques and collected in a holey carbon grid.The Fe 30 Ni 70, Fe 50 Ni 50, are very similar showing the formation of the ordered FeNi compound. In the Fe 70 Ni 30 composition the formation of a mixture of phases was observed, the ordered FeNi and the disordered Fe(Ni) compounds. The mixture of these systems with Ag showed the metal compounds surrounded by Ag forming islands of Fe x Ni y -Ag, There was also evidence of Ag diffusing into the FeNi resulting in the formation of a FeNiAg phase. Backscattered images together with EDX analysis confirmed this result as seen in Fig. 1. For low Ag content (5%), silver seems to joint the grains and help sintering. For high Ag content 60%, islands of FeNi surrounded by Ag are observed. Sintering is always improved with the Ag content. Backscattered electron diffraction patterns were taken on the different Fe x Ni y phases showing a cubic symmetry for all the cases studied. References[1] N.