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http://www.igg.cas.cn/rssdy/201112/W020111212317676398542.pdf

Assessment of heavy metal pollution from a Fe-smelting plant in urban river sediments using environmental magnetic and geochemical methods

Phase transformation and mechanical behavior in annealed 2205 duplex stainless steel welds

Provided is a coated implantable medical device, comprising: a substrate; and a coating disposed on said substrate, wherein said coating comprises at least one polymer and at least one pharmaceutical agent in a therapeutically desirable morphology and/or at least one active biological agent and optionally, one or more pharmaceutical carrying agents; wherein substantially all of pharmaceutical agent and/or active biological agent remains within said coating and on said substrate until the implantable device is deployed at an intervention site inside the body of a subject and wherein upon deployment of said medical device in the body of said subject a portion of said pharmaceutical agent and/or active biological agent is delivered at said intervention site along with at least a portion of said polymer and/or a at least a portion of said pharmaceutical carrying agents.

Drug delivery medical device

Tribological properties of powder metallurgy – Processed aluminium self lubricating hybrid composites with SiC additions

Energy-dispersive spectroscopy and electron backscatter diffraction analysis of isothermally aged SAF 2507 type superduplex stainless steel

This paper presents the possibility of syntactic foam production by pressure infiltration technology. Syntactic foams have low density and relatively high strength. Therefore they can be the material of many important parts in automotive technology or in aviation. The parameters of infiltration were studied and physical and mechanical investigations were performed. Microscopic investigations showed almost perfect infiltration at the applied infiltration pressure. The densities of the foams were significantly decreased. Low density ensures good specific properties and economical energy consuming in the case of moving the parts. Syntactic foams showed a plateau region in their upsetting diagrams and absorbed a high energy during upsetting. The effect of aspect ratio was also investigated. Specimens with higher aspect ratios showed lower peak stress, lower plateau level and higher modulus of elasticity.

/pdf/producing-metal-matrix-syntactic-foams-by-pressure-4at31i7tlc.pdf

Producing metal matrix syntactic foams by pressure infiltration

It is experimentally shown that a thin layer of silica flux leads to an increased depth of weld penetration during activated TIG (=A-TIG) welding of Armco iron. The oxygen-content is found higher in the solidified weld metal and it is linked to the increased depth of penetration through the reversed Marangoni convection. It is theoretically shown for the first time that the basic reason of the reversed Marangoni convection is the phenomenon called “surface phase transition” (SPT), leading to the formation of a nano-thin FeO layer on the surface of liquid iron. It is shown that the ratio of dissolved oxygen in liquid iron to the O-content of the silica flux is determined by the wettability of silica particles by liquid iron. It is theoretically shown that when the silica flux surface density is higher than 15 µg/mm2, reversed Marangoni flow will take place along more than 50 pct of the melted surface. Comparing the SPT line with the dissociation curves of a number of oxides, they can be positioned in the following order of their ability to serve as a flux for A-TIG welding of steel: anatase-TiO2 (best)-rutile-TiO2 (very good)-silica-SiO2 (good)-alumina-Al2O3 (does not work). Anatase (and partly rutile) are self-regulating fluxes, as they provide at any temperature just as much dissolved oxygen as needed for the reversed Marangoni convection, and not more. On the other hand, oxygen can be over-dosed if silica, and other, less stable oxides (such as iron oxides) are used.

An Improved Theoretical Model for A-TIG Welding Based on Surface Phase Transition and Reversed Marangoni Flow

Three types of hollow microspheres with different average diameters (100–150 μm) and two aluminium alloys as matrix material were used to produce metal matrix syntactic foams (MMSFs) by pressure infiltration. The phases, which formed at matrix-filler interface, were investigated by X-ray diffraction (XRD) and energy dispersive spectrometry (EDS). The investigation showed that in syntactic foams, with the Al99.5 matrix, an exchange reaction took place between the matrix and the amorphous components of ceramic hollow microspheres. The reaction resulted in significant formation of alumina and Si precipitates. Because of this diffusion reaction, the hollow microspheres’ walls were degraded. In the case of the AlSi12 matrix the reaction was suppressed by the considerable Si content of the matrix. Therefore, the wall of the hollow microspheres remained unharmed and no real interface layer was found.

Microstructural characterisation of syntactic foams

Ceramic and carbon fiber reinforced aluminium metal matrix composite wires were produced with diameters from 0.1 to 2.5 mm and fiber content of up to 60% v/o. The carbon fibers were CVD or electroplated to improve wettability. Due to the high production rate, interface reactions were reduced significantly, resulting in excellent mechanical properties. Composite wires produced using the continuous process are suitable to simplify the introduction of fiber reinforcements into aluminium castings as well as the production of double composite, sandwich and preferentially reinforced structures. Mechanical tests show that structures reinforced with the composite wires have significantly higher load carrying capacity than structures reinforced directly with fibers or structures without any reinforcement.

János Dobránszky

Papers

Energy-dispersive spectroscopy and electron backscatter diffraction analysis of isothermally aged SAF 2507 type superduplex stainless steel

Producing metal matrix syntactic foams by pressure infiltration

An Improved Theoretical Model for A-TIG Welding Based on Surface Phase Transition and Reversed Marangoni Flow

Microstructural characterisation of syntactic foams

Aluminium double composite structures reinforced with composite wires