Gestione delle anime inorganiche nell’industria fusoria dell’alluminio: stato dell’arte

Nell’industria fusoria dell’alluminio il tema della gestione delle anime da fonderia è di particolare rilievo. L’obiettivo dell’azzeramento delle emissioni inquinanti in atmosfera, in un’ottica di impatto ambientale eco-friendly, ha fatto sì che sia tendenza crescente nelle fonderie l’adozione di anime basate su sistemi di leganti inorganici. In presenza di alti volumi produttivi di componenti ottenuti tramite colata in conchiglia permanente, le anime a legante inorganico sono da prediligere in quanto permettono di eliminare emissioni nocive e migliorare la produttività complessiva dell’impianto. Tuttavia, l’adozione di tali anime comporta la necessità di adottare particolari accorgimenti al fine di garantirne il loro corretto utilizzo, ottimizzando così il processo di colata. Infatti, l’igroscopicità di questa tipologia di anime può creare importanti difettologie in fase di colata dei getti, nonché indebolimento delle anime e loro possibile frattura, spostamento o deformazioni in fase di colata. L’obiettivo di questo lavoro è presentare uno stato dell’arte sull’attualità industriale, relativo alle fonderie di alluminio, in termini di adozione di anime realizzate con sistemi leganti inorganici, loro gestione e possibili difetti nei getti ad esse correlati. Tale stato dell’arte sarà tale da guidare il più possibile verso i know-how necessari ad ottimizzare al meglio gestione ed adozione delle anime

Development and Characterization of New Functionally Graded Aluminium Alloys

Nowadays, aluminium alloys are adopted mainly to produce engineering and automotive components. The present investigation aims to design, cast and characterize novel functionally graded materials (FGMs) produced using Al-Mg and Al-Si alloys by gravity casting technique. Alloys were sequentially cast into a mould to obtain an FGM to realizing great mechanical and metallurgical bonding. Zn addition was further performed in FGM to increase the mechanical properties, thanks to the nucleation of the intermetallic phases MgZn2. Castings were subsequently mechanically tested by tensile tests, bending tests, hardness and microhardness measures to assess the products\u27 quality. Microstructural characterizations were performed along the FGM to assess the metallurgical bonding and evaluate the microstructures obtained. Fracture, microstructural and compositional analysis will highlight the quality of this new FGM proposed. Possible applications of these materials are suggested, as automotive pistons or structural components

Effetto di affinante e modificante sulla microstruttura delle leghe Al-Si da colata = Effect of refining and modification on the microstructure of Al-Si casting alloys

La necessità di ridurre le emissioni di CO2 ha spinto i produttori di veicoli verso l’adozione di materiali in grado di garantire una riduzione del peso quanto più possibile consistente. Per questa ragione, oltre che per le buone proprietà meccaniche specifiche, le leghe alluminio-silicio trovano vasta applicazione nel settore dell’autoveicolo. Sebbene le leghe Al-Si siano leghe note e oggetto di numerosissimi studi, un ulteriore passo in avanti può coinvolgere la valutazione degli effetti degli additivi modificanti ed affinanti sulla microstruttura della lega e sulla forma delle fasi intermetalliche. In questo lavoro, dei getti in lega EN AC 45300 (AlSi5Cu1Mg), verranno analizzati nello stato as-cast e in seguito a trattamento termico T6, con e senza l’adozione di agenti affinanti e modificanti, con l’obiettivo di studiare le evoluzioni che avvengono nelle microstrutture in termini di morfologia delle fasi intermetalliche

Detection chain and electronic readout of the QUBIC instrument

The Q and U Bolometric Interferometer for Cosmology (QUBIC) Technical Demonstrator (TD) aiming to shows the feasibility of the combination of interferometry and bolometric detection. The electronic readout system is based on an array of 128 NbSi Transition Edge Sensors cooled at 350mK readout with 128 SQUIDs at 1K controlled and amplified by an Application Specific Integrated Circuit at 40K. This readout design allows a 128:1 Time Domain Multiplexing. We report the design and the performance of the detection chain in this paper. The technological demonstrator unwent a campaign of test in the lab. Evaluation of the QUBIC bolometers and readout electronics includes the measurement of I-V curves, time constant and the Noise Equivalent Power. Currently the mean Noise Equivalent Power is ~ 2 x 10⁻¹⁶ W/√Hz

Detection chain and electronic readout of the QUBIC instrument

The Q and U Bolometric Interferometer for Cosmology (QUBIC) Technical Demonstrator (TD) aiming to shows the feasibility of the combination of interferometry and bolometric detection. The electronic readout system is based on an array of 128 NbSi Transition Edge Sensors cooled at 350mK readout with 128 SQUIDs at 1K controlled and amplified by an Application Specific Integrated Circuit at 40K. This readout design allows a 128:1 Time Domain Multiplexing. We report the design and the performance of the detection chain in this paper. The technological demonstrator unwent a campaign of test in the lab. Evaluation of the QUBIC bolometers and readout electronics includes the measurement of I-V curves, time constant and the Noise Equivalent Power. Currently the mean Noise Equivalent Power is ~ 2 x 10⁻¹⁶ W/√Hz

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements