检索结果-南通市图书馆

Influence of Microstructures on Polarization Resistance and Hydrogen-Induced Cracking of a Micro-Alloyed Steel Submitted to Different Cooling Rates

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2011年第S1期18卷 168-172页

作者： González M R Martins de Araújo D S Goldenstein H Alonso-Falleiros N departamento de engenharia Metalúrgica e de materiais EscolaPolitécnicaUniversidade de Sao Paulo-SP-Brasil

The effect of different microstructures on the polarization resistance (Rp) and the hydrogen-induced cracking (HIC) of a micro-alloyed steel austenitized and submitted to different cooling rates was *** 19.1 x 6 x 2 mm,containing the whole thickness of the plate were extracted from a 20 mm plate and heat treated on a quenching dilatometer,were submitted to Rp and HIC corrosion *** Rp and HIC tests followed as close as possible ASTM G59 and NACe standard TM0284-2003,in this case,modified only with regard to the size of the *** samples transformed from austenite by a slow cooling (cooling rate of 0.5℃.s-1) showed higher susceptibility to hydrogen-induced cracking,with large cracks in the middle of the sample propagating along segregation bands,corresponding to the centerline of the plate *** cooling rates of 10℃.s-1,only small cracks were found in the matrix and micro cracks nucleated at non-metallic *** higher cooling rates (40℃.s-1) very few small cracks were detected,linked to non-metallic *** result suggests that structures formed by polygonal structures and segregation bands (were eutectoid microconstituents predominate) have higher susceptibility to *** predominantly formed by acicular ferrite make it difficult to propagate the cracks among non-oriented and interlaced acicular ferrite *** segregation bands containing eutectoid products also help inhibit cracking and crack propagation;segregation bands can function as pipelines for hydrogen diffusion and offer a path of stress concentration for the propagation of cracks,frequently associated to non-metallic *** resistance essays performed on the steel in theas received condition,prior to any heat treatment,showed larger differences between the regions of the plate,with a considerably lower Rp in the *** austenitization heat treatments followed by cooling rates of 0.5 e 10℃.s-1 made more uniform the

关键词： hydrogen induced cracking polarization resistance micro-alloyed steel control cooling

Poly(Butylene Adipate-Co-Terephthalate)and Poly(ε-Caprolactone)and Their Bionanocomposites with Cellulose Nanocrystals:Thermo-Mechanical Properties and Cell Viability Study

在线全文

学校读者我要写书评

暂无评论

Journal of Renewable Materials 2019年第3期7卷 269-277页

作者： Marcia Cristina Branciforti Caroline Faria Bellani Carolina Lipparelli Morelli Alice Ferrand Nadia Benkirane-Jessel Rosario elida Suman Bretas departamento de engenharia de materiais Universidade de Sao PauloSao CarlosSPBrasil departamento de engenharia de materiais Universidade Federal de Sao CarlosSao CarlosSPBrasil Institut National de la Santéet de la Recherche Médicale Universitéde StrasbourgStrasbourgFrance

Although nanocomposites have recently attracted special interest in the tissue engineering area,due to their potential to reinforce scaffolds for hard tissues applications,a number of variables must be set prior to any clinical *** manuscript addresses the evaluation of thermo-mechanical properties and of cell proliferation of cellulose nanocrystals(CNC),poly(butylene adipate-co-terephthalate)(PBAT),poly(ε-caprolactone)(PCL)films and their bionanocomposites with 2 wt% of CNC obtained by casting *** nanocrystals extracted from Balsa wood by acid hydrolysis were used as a reinforcing phase in PBAT and PCL matrix *** films and pure CNC at different concentrations were cultured with osteoblasts MG-63 and the cell proliferation was assessed by AlamarBlue?*** thermal-mechanical properties of the films were evaluated by dynamic-mechanical thermal analysis(DMTA).It was found by DMTA that the CNC acted as reinforcing *** addition of CNCs in the PBAT and PCL matrices induced higher storage moduli due to the reinforcement effects of *** cell viability results showed that neat CNC favored osteoblast proliferation and both PBAT and PCL films incorporated with CNC were biocompatible and supported cell proliferation along *** nature of the polymeric matrix or the presence of CNC practically did not affect the cell proliferation,confirming they have no in vitro *** features make cellulose nanocrystals a suitable candidate for the reinforcement of biodegradable scaffolds for tissue engineering and biomedical applications.

关键词： Cell viability thermo-mechanical properties cellulose nanocrystals(CNC) biocompatible polymers tissue engineering bionanocomposites

Remarks on the application of two-dimensional shape factors under severe wear conditions

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Friction 2016年第1期4卷 65-71页

作者： Giuseppe PINTAUde Mario COSeGLIO Programa de Pós-Gradua(a)(a)o em engenharia Mec(a)nica e de materiais UTFPR Curitiba PR Brazil University of Birmingham Birmingham UK

The use of two-dimensional shape parameters to characterize abrasive particles is a potential approach to express their angularity. Nevertheless, in sliding abrasion, especially in pin abrasion testing, these descriptors could not be suitable for characterizing severe wear of engineering materials such as steels and cast irons. This work compares the applicability of two-dimensional shape parameters in describing severe wear of metals in recent pin abrasion tests with cases where they could have been correlated with the wear rates. Considering these aspects, this work puts in evidence the importance of clogging occurrence and the coated paper structure for a carefully application of shape parameters. In addition, it is proposed a possible relation between the shape parameters and one of the components of the abrasion factor.

关键词： wear particle shape sliding abrasion coated papers

Fatigue strength and microstructure evaluation of Al 7050 alloy wires recycled by spray forming,extrusion and rotary swaging

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Transactions of Nonferrous Metals Society of China 2020年第12期30卷 3195-3209页

作者： João G.J.de SALVO Conrado RMAFONSO Programa de Pós-graduação em Ciência e engenharia de materiais(PPG-CeM) Universidade Federal de São Carlos(UFSCar)Rod.Washington LuizKm 23513565-905 São Carlos-SPBrazil Divisão de materiais Instituto de Aeronáutica e EspaçoCTAPraça Marechal Eduardo Gomes5012228-904 São Josédos Campos-SPBrazil departamento de engenharia de materiais(deMa) Universidade Federal de São Carlos(USFCar)Rod.Washington LuizKm 23513565-905 São Carlos-SPBrazil

Recycled high-strength aluminum alloys have limited use as structural materials due to poor mechanical properties. Spray forming remelting followed by hot extrusion is a promising route for reprocessing 7 xxx alloys. The 7050 alloy machining chips were spray formed, hot extruded, rotary swaged and heat-treated in order to improve mechanical properties. Microstructures, tensile properties and fatigue strength results for a 2.7 mm-diameter recycled wire are presented. Secondary phases and precipitates were investigated by XRD, SeM, eBSD, TeM and DSC. As-swaged and heat-treated(solution and aging) conditions were evaluated. Mechanical properties of both conditions outperformed AA7050 aerospace specification. Substantial grain refinement resulted from the extensive plastic deformation imposed by rotary swaging. Refined micrometric and sub-micrometric Al grains, as well as coarse and fine intermetallic precipitates were observed. Subsequent solution treatment resulted in a homogeneous, recrystallized and equiaxed microstructure with grain size of 9 μm. Nanoscale GP(I) zones and η′ phase precipitates formed after aging at 120 ℃, imparting higher tensile(586 MPa) and fatigue(198 MPa) strengths.

关键词： Al−Zn−Mg−Cu alloy spray forming thermomechanical processing microstructure fatigue

Why static bound-state calculations of tetraquarks should be met with scepticism

在线全文

学校读者我要写书评

暂无评论

Chinese Physics C 2017年第5期41卷 49-53页

作者： George Rupp eef van Beveren Centro de Fisica e engenharia de materiais Avancados Instituto Superior Tecnico Universidade de Lisboa P-1049-001 Lisboa Portugal Centro de Fisica da UC Departamento de Fisica Universidade de Coimbra P-3004-516 Coimbra Portugal

Recent experimental signals have led to a revival of tetraquarks,the hypothetical q~2q~2 hadronic states proposed by Jaffe in 1976 to explain the light scalar *** structures with exotic quantum numbers have indeed been observed recently,though a controversy persists as to whether these are true resonances and not merely kinematical threshold enhancements,or otherwise states not of a true q~2q~2 ***,puzzling non-exotic mesons are also often claimed to have a tetraquark ***,the corresponding model calculations are practically always carried out in pure and static bound-state approaches,ignoring completely the coupling to asymptotic two-meson states and unitarity,especially the dynamical effects *** this short paper we argue that these static predictions of real tetraquark masses are highly unreliable and provide little evidence of the very existence of such states.

关键词： meson scalar quark dynamical asymptotic otherwise argue merely decay exotic

Gold Supported on Metal Oxides for Carbon Monoxide Oxidation

在线全文

学校读者我要写书评

暂无评论

Nano Research 2011年第2期4卷 180-193页

作者： Sonia A. C. Carabineiro Nina Bogdanchikova Miguel Avalos-Borja Alexey Pestryakov Pedro B. Tavares Jose L. Figueiredo Laboratário de Catálise e materiais Associate Laboratory LSRE/LCM Departamento de Engenharia Química Faculdade de Engenharia Universidade do Porto 4200-465 Porto Portugal Universidad Nacional Autónoma de México Centro de Nanociencias y Nanotecnologia Carretera Tijuana-Ensenada 22800 Ensenada Baja California México Tomsk Polytechnic University 30 Lenin Avenue Tomsk 634050 Russia Universidade de Trás-os-Montes e Alto Douro Centro de Quimica-Vila Real Departamento de Química 5001-911 Vila Real Portugal

Au has been loaded （1% wt.） on different commercial oxide supports （CuO, La2O3, Y2O3, NiO） by three different methods： double impregnation （DIM）, liquid-phase reductive deposition （LPRD）, and ultrasonication （US）. Samples were characterised by N2 adsorption at -196℃, high-resolution transmission electron microscopy, selected area electron diffraction, energy dispersive X-ray spectrometry, high-angle annular dark-field imaging （Z-contrast）, X-ray diffraction, and temperature programmed reduction. CO oxidation was used as a test reaction to compare the catalytic activities. The best results were obtained with Au loaded by DIM on the NiO support, with an activity of 7.2 × 10^（-4） molco·gAu^（-1）·s^（-1） at room temperature. This is most likely related to the Au nanoparticle size being the smallest in this catalyst （average 4.8 nm）, since it is well known that gold particle size determines the catalytic activity. Other samples, having larger Au particle sizes （in the 2-12 nm range, with average sizes ranging from 4.8 to 6.8 nm）, showed lower activities. Nevertheless, all samples prepared by DIM had activities （from 1.1 × 10^（-4） to 7.2 × 10^（-4） molco·gAu^（-1）·S^（-1）, at room temperature） above those reported in the literature for gold on similar oxide supports. Therefore, this method gives better results than the most usual methods of deposition-precipitation or co-precipitation.

关键词： Gold heterogeneous catalysis oxidation electron diffraction X-ray diffraction

Comparison of Different Formulations for the Numerical Calculation of Unsteady Incompressible Viscoelastic Fluid Flow

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Advances in Applied Mathematics and Mechanics 2010年第4期2卷 483-502页

作者： L.J.Amoreira P.J.Oliveira departamento de Fisica Unidade de Detecccao RemotaUniversidade da Beira InteriorP6201-001 CovilhãPortugal departamento de engenharia electromecânica Unidade de Materiais Têxteis e PapeleirosUniversidade da Beira InteriorP6201-001 CovilhãPortugal

In this paper we compare different methods currently used in the stabilization of numerical simulations of time-dependent viscoelastic fluid flows described with the Oldroyd-B and related *** methods under consideration,based on the separation of newtonian-like components from the stress tensor,are applied to a finite volume analysis of two simple benchmark problems(the plane Poiseuille startup and pulsated flows),for which analytical solutions are *** relative performances of each method are evaluated regarding stability,accuracy and efficiency.

关键词： Time-dependent viscoelastic flows oscilating flow start-up flow computational rheology

Product development cost estimation through ontological models-a literature review

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Management Analytics 2019年第2期6卷 209-229页

作者： Rafael Voltolini Kaio Vasconcelos Milton Borsato Margherita Peruzzini Programa de Pós-Graduação em engenharia Mecânica e de materiais(PPGeM) Universidade Tecnológica Federal do Paraná(UTFPR)CuritibaBrasil Dipartimento di Ingegneria“enzo Ferrari”(DIeF) Universitàdegli Studi di Modena e Reggio Emilia(UNIMORE)ModenaItaly

The early stages of product development are characterized by *** must deal with challenges that arise unexpectedly in an agile and responsive *** information systems based on ontological models are a promising approach to capture knowledge and rationale of domain specialists,either for decision making or knowledge *** present study presents a bibliometric analysis on the use of ontologies in product development for cost *** identifies trends and research opportunities that can orient future *** a general search in scientific databases,31 articles were found and selected based on criteria established using the Proknow-C *** indicate that there are several possibilities for solutions using ontological and hybrid,transdisciplinary *** intelligent systems is not only promising but is also challenging as a new and real transdisciplinary research area of interest.

关键词： Proknow-C product development ontology cost review

Theoretical Studies of Proton Radioactivity

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

原子核物理评论 2016年第2期33卷 184-189页

作者： Lidia S. Ferreira enrico Maglione Centro de Fisica e engenharia de materiais CeFeMA and departmento de Fisica Instituto Superior Tecnico Universidade de Lisboa Av Rovisco Pals 1049 001 Lisboa Portugal Dipartimento di Fisica e Astronomia "G. Galilei" Via Marzolo 8 1-35131 Padova Italy Istituto Nazionale di Fisica Nucleate Padova Italy

In the paper, we will discuss the most recent theoretical approaches developed by our group,to understand the mechanisms of decay by one proton emission, and the structure and shape of exotic nuclei at the limits of s... 详细信息

关键词： proton radioactivity drip-line nuclear density functional theory