323,270 research outputs found
Visual appearance and scratch resistance of high performance thermoset and thermoplastic powder coatings
No full textA comparative evaluation of electrostatic spray and 'hot dipping' fluidized bed to deposit two different organic paints belonging to the class of thermoplastic (PPA571, an alloy of acid modified polyolefins) and thermoset (TGIC-free transparent pigmented bronze polyester) powders was performed. Visual appearance of the investigated coatings was evaluated by colour, gloss and coating thickness measurements as well as by the determination of the surface morphologies. Micro-mechanical performance of the coatings was assessed by progressive load scratch tests. 'Hot dipping' fluidized bed is found a fast deposition technique as, after substrate pre-heating, it takes just few seconds to have the part completely powder coated. On the other hand, electrostatic spray deposition is a potentially selective coating technique, but it lasts longer (generally, 6-15 s) and, moreover, the coated parts must be post-cured for long time (at least, 15 min) and at high temperature (150-200 °C) to give rise to the formation of continuous films. Indeed, whilst 'hot dipping' fluidized bed is found particularly suitable for the deposition of thick and smooth thermoplastic coatings, electrostatic spray deposition is found the most viable technique to deposit thinner and highly scratch and wear resistant thermoset coatings
«Per non dar moto alle fabriche»: l'ingegnere regio Scipione Basta e la costruzione della cappella Roano nel duomo di Monreale
No full text«PER NON DAR MOTO ALLE FABBRICHE»: THE ROYAL ENGINEER SCIPIONE BASTA AND THE CONSTRUCTION OF THE ROANO CHAPEL IN THE CATHEDRAL OF MONREALE. In December 1686 the Royal Engineer Scipione Basta, a personality still largely to be investigated but which seems to portend a specific expertise in techno-constructive issues and in particular in structural reinforcement, was appointed by the Viceroyal Government to draw up a technical report concerning some delicate constructive aspects of the project of the architect fra Giovanni da Monreale for the chapel commissioned by the archbishop Roano for the cathedral.
Due to the particular configuration of the building to be constructed –a domed octagonal chapel built on a vaulted alley to allow the passage of the pre-existing public street– the engineer dictated a number of requirements in order to ensure not only the firmness of the building, but also that the thrusting elements of the new structure (arches, vaults and dome) with their stresses would not cause damage to the ancient Norman cathedral and in particular to its precious mosaic decorations
Manufacturing of steel foams by Slip Reaction Foam Sintering (SRFS)
No full textThis manuscript deals with the manufacture of steel foams by Slip Reaction Foam Sintering (SRFS). Closed cell steel foams were synthesized by steel powders, H3PO4, silica and water. Experimental tests were performed to study the influence of steel powders, H3PO4, silica and water weight% on the overall mechanical performance of the steel foams. The analysis of each operational parameter was performed by ANalysis Of VAriance (ANOVA). The experimental findings revealed the manufactured metal foams were characterized by mechanical energy absorption as high as 10mJ, making these materials very promising in several technological fields. Further, the use of a statistical approach allowed to identify the best settings of the process parameters, with reduced silica and H3PO4 content and increased water concentration found to increase the energy absorption capability and the overall product quality
Geometria e Pittura. Il primo volume del Ryakuga haya oshie di Katsushika Hokusai (1760-1849)
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