18 research outputs found
Genga e il cantiere decorativo dell’Imperiale: protagonisti e comparse
No full textViene esaminata la decorazione della Villa Imperiale di Pesaro, voluta dal duca Francesco Maria della Rovere. Alla luce dei pochi documenti e delle scarse testimonianze delle fonti, vengono ripercorsi gli interventi dei numerosi pittori coinvolti sotto la guida di Girolamo Genga. Accanto a Francesco Menzocchi e a Raffaeillino del Colle, l'Autore propone per la prima volta di riconoscere il giovane Nicolò dell'Abate, all'opera nella sala con il Giuramento di Sermide. Altre precisazioni riguardano i paesaggi eseguiti da Camillo Mantovano.The decoration of the Imperial Villa of Pesaro is examined, requested by Duke Francesco Maria della Rovere. In light of the few documents and the scarce evidence of the sources, the interventions of the numerous painters involved under the guidance of Girolamo Genga are traced. Next to Francesco Menzocchi and Raffaeillino del Colle, the author proposes for the first time to recognize the young Nicolò dell'Abate, at work in the room with the Oath of Sermide. Other clarifications concern the landscapes painted by Camillo Mantovano
Effects of Ni-Mo binder and laser surface engineering of NbC based cutting inserts during face-milling of automotive grey cast iron
No full textA research report submitted in fulfillment of the requirements for the Doctor of Philosophy, In the Faculty of Engineering and the Built Environment , School of Mechanical, Industrial and Aeronautical Engineering, University of the Witwatersrand, Johannesburg, 2024The main aim of this study was to design, develop and produce NbC-Ni cermet based cutting inserts as potential substitutes for conventional WC-Co based inserts for the face-milling machining of automotive grey cast iron (a-GCI), an alloy that plays a critical role in the automotive manufacturing industry. For this purpose, rapid pulsed electric current sintering (PECS), additions of Mo as a partial binder replacement and TiC and TiC 7 N3 as secondary hard phases, and femtosecond laser surface modification (LSM) technique were used in an effort to enhance the NbC-Ni based cutting inserts’ machining capabilities during face-milling of a- GCI. All the sintered samples achieved relative densities of 97% and above, irrespective of the sintering process. Adding Mo, TiC and TiC 7 N3 to the NbC-12Ni (wt%) composition refined the NbC grain size in PECS samples, enhancing hardness and wear resistance. Mechanical impact shock and wear resistance of inserts were further improved via femtosecond LSM, creating pyramid (P) LSM and shark skin (S) LSM based micro-patterns on the surface of the cutting inserts. Face milling machining tests of a-GCI were performed at 200-400 m/min cutting speed () and 0.25-1.0 mm depth of cut (ap ). The inserts’ cutting-edge wear and failure were evaluated after every pass using optical microscopy and analysed via high angular annular dark field (HAADF)-scanning electron transmission microscopy (STEM). Machining performance was assessed by technique for order of preference by similarity to ideal solution (TOPSIS) based model using insert tool life (), specific cutting energy () and maximum resultant cutting forces (Fmax ) as criteria and including surface roughness (Ra) during finishing operations. The pyramid LSM PECS NbC-10TiC-12N[Ni/Mo] (wt%) (R2MS-P1) insert was the top performer during semi-finishing, with 20 min , 22 J/mm 3 and 1087 N Fmax , obtaining an overall preference score () of 0.953. The best inserts during finishing 2 were the blank (B) (i.e. unmodified cutting edge) PECS NbC-10TiC 7 N3 -12Ni (wt.%) (TCN1S-B3) and LPS WC-10TiC-10[Co/Mo] (wt.%) (T1ML-B3) inserts with both inserts obtaining s of 0.826, respectively. In general, additions of Mo, TiC, TiC7 N3 , PECS and LSM improved hardness and abrasion wear resistance, resulting in enhanced performance of NbC-Ni based cutting inserts during machining.MM202
Microstructure and properties of selected WC-cemented carbides manufactured by SPS method
No full textThe effects of spark plasma sintering (SPS), WC starting particle size (0.1-0.8 μm), NbC, TiC and Mo2C additions on the microstructure and mechanical properties of WC-Co and WC-Ni alloys were investigated. Spark plasma sintering has the main advantage of very high degrees of densification obtainable at low temperatures within short sintering times, preventing Ostwald ripening. Spark plasma sintered WC-0.5Cr3C2-10Co (wt%) and WC-9.3Ni (wt%) samples had finer WC grains with poorly distributed binder pools than similar liquid phase sintered (LPS) samples, resulting in higher hardness, lower fracture toughness (K1C) and transverse rupture strength (TRS). Although the SPS samples had smaller WC grains than the LPS samples, WC grains of up to 1μm occurred in the nano and ultrafine grades, due to coalescence of fine particles. High NbC additions (≥20 wt%) to WC-10Co (wt%) reduced the WC grain size, hardness, K1C, TRS and modulus of elasticity in all grades. The poor mechanical properties were attributed to the reduction of WC volume fraction, formation of the (Nb,W) solid solution and poor wetting of NbC by Co. Additions of 6.25 wt% TiC and 0.5-5 wt% Mo2C to the WC-9.3Ni (wt%) nano and ultrafine samples gave the finest WC grain sizes, due to good grain growth inhibition. Molybdenum carbide also improved the Ni binder distribution due to better wetting of WC by the Ni. The refined microstructure and improved Ni binder distribution, together with reduced binder amount (7 wt%) gave >20 GPa hardness, slight reduction in K1C, good modulus of elasticity and lower TRS.
The abrasion wear resistance increased with reduced WC grain size and binder amount, explaining the significantly higher abrasion resistance of the SPS WC-5Mo2C-6.25TiC-7Ni (wt%) ultrafine and nano grades than the LPS samples. The LPS WC-9.3Ni sample, had higher abrasion wear resistance than the LPS WC-0.5Cr3C2-10Co (wt%) sample, because of the slightly lower binder content and the Ni binder’s better wear properties. The LPS samples had the highest thermal shock and impact resistance (higher TRS and K1C). The WC-0.5Cr3C2-5NbC-10Co (wt%) sample had a good hardness, from SPS and the addition of NbC and Cr3C2 grain growth inhibitors, as well as good K1C and TRS, from its high binder amount and good wetting of WC by Co. These resulted in a good combination of abrasion wear, thermal shock and impact resistance in the WC-0.5Cr3C2-5NbC-10Co (wt%) sample. The WC-5Mo2C-6.25TiC-7Ni (wt%) ultrafine grade sample had the lowest thermal shock and impact resistance because of its poor K1C and TRS
Brief Note Transmission Experiments with Babesia Microti (Gray Strain) Using Dermacentor Andersoni Stiles as a Vector
No full textAuthor Institution: Department of Microbiology, The Ohio State Universit
Property and structural characterisation of Fe and FeNi bonded NbC cermets for high temperature wear applications
No full textSulla camera di Alessandro e Rossane alla Farnesina e sui soggiorno romani del Sodoma (con una nota su Girolamo Genga a Roma e le sue relazioni con i Chigi)
No full textIl saggio getta un nuovo fascio di luce sulla vicenda del Sodoma tra il secondo e il terzo decennio del Cinquecento, quando decisivi furono i suoi ripetuti soggiorni a Roma. Sia sul piano biografico (quantomeno della committenza) sia delle esperienze figurative, fondamentale per il pittore fu in questi anni Raffaello, che rappresentò per il Sodoma un costante punto di riferimento. È questo, tuttavia, un nodo storiografico ancora da chiarire nei suoi vari aspetti, a partire dal ruolo avuto da Raffaello nella progettazione della decorazione della camera nuziale di Agostino Chigi alla Farnesina (la cosiddetta camera di Alessandro e Rossane). Nella prima parte dello studio l’attenzione è concentrata appunto su questo ciclo di affreschi: ne è esaminato il programma iconografico, è tratteggiato il milieu culturale in cui prese vita ed identificato il possibile ideatore, mentre grazie a nuovi materiali grafici emerge confermata l’ipotesi della responsabilità progettuale di Raffaello nelle fasi iniziali della commissione, prima - cioè - che questa fosse trasferita al Sodoma.Tale esperienza romana del pittore vercellese, che nuove riflessioni portano a circoscrivere agli anni 1516-17, mostra la grande parte avuta di Raffaello nello sviluppo della pittura del Sodoma; un ascendente che si precisò e si arricchì ulteriormente nel corso di un successivo trasferimento del Sodoma a Roma all’aprirsi degli anni venti, rivelato da inediti documenti presentati in questa sede. L’autore può così ridefinire uno dei tratti finora più oscuri nella carriera del pittore vercellese: un momento che in realtà fu decisivo, anche perché innervato da esperienze che costituirono la premessa per le sue opere più celebrate già a partire dal Cinquecento, quelle realizzate a Siena a partire dal 1524-25. Il discorso ambientato nella Roma dei primi anni venti si conclude - continuando l’indagine sull’entourage dei Chigi - con un tentativo di revisione degli estremi e della natura del soggiorno romano di Girolamo Genga, il quale - al pari del Sodoma - intrecciò sicure, per quanto finora trascurate, relazioni con Sigismondo Chigi. // This paper casts new light on the work of Sodoma between the second and the third decade of the 1500s, at the time of the latter's repeated visits to Rome. At this time Raphael, who for Sodoma was a constant source of inspiration, was fondamentale for the painter both on the biographical level (at least of the patronage), and as regards his figurative style. It is an historiographical topic that still needs to be clarified completely, starting with Raphael's role in the planning of the decoration of Agostino Chigi's wedding chamber at the Farnesina (the so-called Room of Alexander and Roxane). In the first part of the study attention is focused on this cycle of frescoes: its iconographic programme is examined, the cultural milieu from which it emerge is outlined and its possible creator is identified, while thanks to new graphic material the hypothesis of Raphael's planning in the initial phases of the commission is confirmed, that is, before it was passed on to Sodoma. The latter's time in Rome, which new reflections pinpoint to the years 1516-17, shows the significant part played by Raphael in the development of Sodoma's painting; an influence that became clear and was further enriched in the course of a subsequent move to Rome by Sodoma at the beginning of the 1520s and revealed by unpublished documents presented here. The author is thus able to redefine what was hitherto been one of the most obscure periods in the career of the painter from Vercelli: a time that was in fact decisive since it was animated by experiences that heralded his most celebrated works already from the 16th century, those produced in Siena from 1524-25. The part relating to Rome in the early 1520s ends - continuing the analysis of the Chigi's family entourage - with an attempted revision of the details and nature of the sojourn in Rome of Girolamo Genga who, like Sodoma, entertained certain, although previously unstudied, relations with Sigismondo Chigi
Toward sustainable industrialization in Africa: the potential of additive manufacturing – an overview
No full textThe integration of sustainable additive manufacturing (AM) within the framework of African industrialization presents a promising avenue for economic advancement while addressing environmental concerns. This review explores the convergence of sustainable AM practices with the industrial landscape of Africa, highlighting potential benefits and challenges. Through efficient resource utilization and localized production capabilities, AM holds promise for enhancing industrial resilience, stimulating employment opportunities, and fostering innovation. However, the realization of these benefits necessitates navigating infrastructural limitations, technological disparities, and regulatory complexities. By critically examining sustainable AM strategies and their relevance to African contexts, this review aims to delineate actionable pathways for leveraging the transformative potential of AM. The role of AM in industrialization as expressed in the African Union Agenda 2063 are highlighted. This has the potential to increase the staggering ∼11% contribution of manufacturing to gross domestic product of Africa. Collaboration through the triple helix approach focusing on government, industry and academia is highly pivotal for the success of such nascent and ubiquitous AM technology which is able to address the sustainable development goals. Africa can leapfrog and harness sustainable AM as a catalyst for inclusive industrial development and sustainable growth across the continent. The implications of AM for an industrialised Africa and areas for future research direction are briefly discussed
Characterisation and parametric optimisation of LPBF and DIW of WC12wtCoMo cemented carbides using response surface methodology
No full textEffects of femtosecond laser surface modified WC and NbC based inserts during the facemilling of of automotive Grey Cast Iron aGCI
No full text
