Materials Literature
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A new welding method which allows the assembly of two titanium nitride coated titanium parts is proposed. The welding procedure utilizes the possibility for pulse-shaping in order to change the energy distribution profile during the laser pulse. The pulse-shaping is composed of three elements: a) a short high power pu…
Polymer composites used above their glass transition temperatures Tg present a substantial degradation of physical properties; therefore a material's glass transition temperature and its change with moisture absorption are of practical importance. Little attention has been paid to the role of the adhesive bonding betw…
Aluminum-lithium alloys are candidate materials for many aerospace applications because of their high specific strength and elastic modulus. These alloys have several unique characteristics such as excellent fatigue crack growth resistance when compared with that of the conventional 2000 and 7000 series alloys. In thi…
The thermal decomposition of titanium hydride powder (delta-phase) to titanium (alpha-phase) was investigated by means of thermogravimetric analysis (TGA) and high-temperature X-ray diffraction (HTXRD) in high vacuum. The delta-to-alpha phase transformation was followed in situ by HTXRD at temperatures varying from ro…
In this work, (100) oriented monocrystalline silicon samples were single point diamond turned under conditions that led to a ductile and brittle regime. Raman spectroscopy results showed that the ductile regime diamond turning of silicon surfaces induced amorphization and, on the contrary, in the brittle mode machinin…
Phospho-tungstic and phospho-molybdic Wells-Dawson heteropolyacids, H6P2W18O62 .xH2O and H6P2Mo18O62 .xH2O respectively, were synthesized through ion exchange with a higher yield (~ 90%) than the conventional organic route (~ 70%). Pure, non-degraded heteropolyacids are obtained when the corresponding ammonium salt [(…
Surface rolling is a process extensively employed in the manufacture of ductile cast iron crankshafts, specifically in regions containing stress concentrators with the main aim to enhance fatigue strength. Such process hardens and introduces compressive residual stresses to the surface as a result of controlled strain…
In this work titanium sol was prepared from tetraethylorthotitanate (TEOT) in ethanol, stabilized with beta-diketonate 2,4 pentanedione in molar ratio 1:1 homogenized by magnetic stirring, europium ion was add as structural probe. The xerogels were heat treated at 500, 750 and 1000 °C and the characterization was real…
The evolution in the understanding of the recrystallization phenomena is summarized in this paper. Initially the main developments concerning recrystallization are presented from a historical perspective. Definitions and concepts involving recrystallization are presented regarding it as a solid-state reaction that occ…
Impurity interstitial atoms present in metals with BCC structure can diffuse in the metallic matrix by jumps to energetically equivalent crystallographic sites. Anelastic spectroscopy (internal friction) is based on the measurement of mechanical loss or internal friction as a function of temperature. Due to its select…
In this work, copper-zinc alloy coatings on mild steel substrates were obtained in nontoxic pyrophosphate-based electrolytes, at room temperature and under continuous current. The effects of bath composition and current density on the hardness of the coatings, as well as on their morphologies, were evaluated. The resu…
This work involved the application of luminescence spectroscopy under steady-state conditions to study the curing process of the epoxy resin diglycidyl-ether of bisphenol-A (DGEBA) using the curing agents 4,4'-diaminodiphenylmethane (DDM) and 4,4'-diaminodiphenylsulfone (DDS). Two fluorescence methods were employed: t…
Cellular automata simulation of recrystallization in two dimensions is carried out. The simulated microstrutural evolution is compared in detail with the predictions from mathematically exact analytical theories considering both kinetic and geometrical aspects. Very good agreement is observed between the cellular auto…
Quartz with aluminum as impurity absorbs energy from ionizing radiation and modifies its color. Colorless quartz becomes smoky or dark smoky (morion quartz) when exposed to gamma rays. By heat-treatment, smoky quartz may become successively greenish, yellowish, or brownish as the irradiation dose increases. Natural, c…
The optical properties of single mode fibers, which are drawn from the silica preform made by MCVD technique, have been studied. The properties such as cutoff wavelength, chromatic dispersion, and polarization mode dispersion (PMD) were studied for 2.3 km length of single mode fiber (SMF). The cutoff wavelength was me…
Marine corrosion data for mild steel coupons exposed at various immersion depths at various geographical locations are reviewed. Analysis of the data confirms that oxygen concentration and water temperature are important parameters influencing corrosion weight loss as a function of time and that there is no obvious ef…
Abstract The strengthening effect of grain boundaries and dislocation boundaries is a traditional metallurgical theme, which at the present time is being revived. The reason is the scientific and industrial interest in strength obtained through a structural refinement. Such a refinement is found in nanocrystalline met…
A new type of photo-active nano-composite material appropriate for Ultra-fast Nonlinear Optical χ (3) (ω) applications has been synthesized and optically characterized. Compared to standard noble metal particles- oxide nano-composites exhibiting a superior effective χ (3) (ω) due to the enhancement of the local electr…
This study of structural concrete made with recycled concrete aggregate focuses on two issues: 1. The characterization of such aggregate on the Spanish market. This involved conducting standard tests to determine density, water absorption, grading, shape, flakiness and hardness. The results obtained show that, despite…