Iris Publishers Material Science Open Access Journal

Growth of Vertically Aligned InGaN Nanowires Material Science InGaN nanowires (NWs) have attracted a lot of research interest in the past decade. They contain both the intrinsic properties of InGaN materials, and some unique properties induced by the NW structures. This article reviews the growth methods to obtain InGaN NWs, with discussions on different epitaxy methods. One-dimensional (1D) semiconducting materials have attracted considerable attention for future device applications, such as nanophotonic and nano electronic devices [1]. Group III-nitride nanowires (NWs), InGaN NW is of tunable bandgap (0.7–3.4 eV), high carrier mobility, and excellent optical absorption, which have demonstrated great potentials for the high-performance photodetectors, light-emitting diodes, and solar cells. The optoelectronic performance of InGaN NW devices is highly associated with the NW morphologies [2]. For instance, poorly defined morphology such as a conical shape may cause a s...

High-Speed Nanomechanical Property Mapping of Polyetherimide/Zinc Titanate Nanocomposites Material Science Determination of mechanical properties of modern nanocomposite materials through conventional macroscale test methods is always challenging and questionable. Nanoparticles interact with polymer molecules at a micron to nanoscale, and hence to precisely determine the properties of these composites, micron level test methods such as nanoindentation need to be utilized. In this work, we have used the nanoindentation techniques combined with a recently developed novel accelerated property mapping (XPM) technique to study the statistical quantification of mechanical properties such as hardness and modulus, and the variance of these properties across the phases of polyetherimide (PEI) nanocomposites reinforced with 5, 10, 15 wt. % of zinc titanate (ZnTiO3) nanoparticles. For more Information: https://irispublishers.com/mcms/fulltext/high-speed-nanomechanical-property-m...

Technology of Preparation of Metal Parts for Heat- Resistant Coating The technological process of surface preparation for heat-shielding coating on the heat-loaded part of the combustion chamber of a liquid rocket engine is Considered. The proposed coating has several layers: internal metal, in contact with the part or substrate, and external, from a mixture of ceramic granules and metal powder. At the same time, to obtain the initial surface for the coating with the required surface layer roughness, it is proposed to use the method of blasting with abrasive grain. The article analyzes the possible mechanisms of formation of transition zones: base – coating - as well as the influence of their chemical composition on the adhesive strength of the layers. The choice of brand and combination of materials used for coating is justified. The technological modes that have been tested in production conditions when applying heat-resistant coatings on parts of modern rocket engines are...

Precision Ellipsometry for Quantitative Real-Time Monitoring of Molecular Layers Precision ellipsometry (PREL) is optical technique that uses polarization modulator to measure changes in the state of light polarization reflected off a surface of a material. Based on new modulation concept, a polarization modulator was made, which is compact, non-magnetic, consuming low power. With this modulator, a portable PREL system was made and was shown to have sensitivity at molecular level via experiments on attachment of various molecules on silicon surface from air and from water. Real-time measurements of kinetics of molecular binding gave insights into mechanisms of the binding and gave directions to improvement of technology of fabrication of respective materials. For more Information: https://irispublishers.com/mcms/fulltext/precision-ellipsometry-for-quantitative-real-time-monitoring-of-molecular-layers.ID.000520.php For More Open Access Journals in Iris Publishers ...

Modeling of Partially Cemented Soils in the Las Vegas Valley Cemented soils deposits located in Las Vegas valley have long been a challenge for engineers. These deposits can distribute considerable loads over a large area. They are, however, difficult to model or to predict their behavior. For engineering purposes, these cemented soils, also commonly referred to as Caliche, are difficult to characterize: their thickness, lateral extent and strength. This erratic and heterogeneous nature can result in inconsistent design and performance of foundations. Fifty-three cored specimens from block samples of partially cemented soils (aka Caliche), collected from the Las Vegas valley, were tested for their unconfined compressive strength (UCS). Laboratory shear and pressure wave velocities were measured for all samples and relationships between lab shear wave velocities, material unit weight and unconfined compressive strength were generated. This article discusses a material model...

Iris Publishers Hot Deformation of Quench Hardened Titanium Alloys As A Modern Production Method of High Strength Structural Parts? Titanium alloys belong to advanced metallic materials used in hi-tech industrial branches, like aeronautics. They are considered as a hard deformable materials - usually hot worked at the temperature of 0.65-0.75 Tmelt. Quite narrow temperature range of hot working makes it difficult to form near net shape parts which do not require additional heat treatment. Industrial manufacturing processes of two-phase α + β titanium alloys – mostly used for structural elements – include usually vacuum casting, initial plastic working of ingots at the temperature range of β phase stability, recrystallization annealing at the same temperature range and again plastic working, but at the temperature range of α + β phase transformation [1]. Hot formed parts made of two-phase titanium alloys are heat treated dependently on demanded microstructure (lamellar...

A Simple Equation Results in Decades of Technical Fun Decades ago, when I was getting my PhD, I needed to calculate the density of a mixture of two polymers. I was tempted to use equation 1 below: Where x is the mass fraction of polymer (or metal for a metal alloy), y the mass fraction of polymer 2, rho the respective densities and rho the total polymer or alloy density The derivation is in the appendix. Others have derived this equation before, as it is in some metallurgy texts. Little did I know at the time that this equation would yield decades of “confrontation” and technical fun. Right after deriving this equation, some of my materials science grad student friends heard about it and asked for the equation. I suggested they derive it themselves and was a bit surprised that they had trouble doing it and sheepishly asked for my help in the derivation. For more Information: https://i...