Search results for "mechanical propertie"

Microstructure and mechanical effects of spark plasma sintering in alumina monolithic ceramics

2013

The specific effects of spark plasma sintering (SPS) on the creep behavior, microstructure and mechanical properties of alumina monolithic ceramic were investigated. SPS introduces strains that concentrate at grain boundaries and inhibit crack growth, resulting in an improvement in the flexural strength and fracture toughness. However, creep blocks grain boundary movements and decreases the reliability of the material. These strains can be removed by a post-sintering thermal treatment, which plays an important role in the distribution of dislocations.

Influence of the chemical composition of monolithic zirconia on its optical and mechanical properties. Systematic review and meta-regression.

2021

Este artículo se encuentra disponible en la siguiente URL: https://www.jstage.jst.go.jp/article/jpr/66/2/66_JPR_D_20_00218/_pdf/-char/en Este artículo de investigación pertenece al número especial "Advances in Personalized Nursing Care". Purpose: This systematic review set out to investigate the influence of chemical composition and specimen thickness of monolithic zirconia on its optical and mechanical properties. Meta-analysis and meta-regression analyzed the effects of variations in percentages of yttrium, aluminum, and specimen thickness of monolithic zirconia. Study selection: The review followed recommendations put forward in the PRISMA checklist. An electronic search for relevant art…

Pressure-induced phase transitions in AgClO4

2011

11 pags, 9 figs, 4 tabs. -- PACS number(s): 62.50.−p, 64.70.K−, 61 .50.Ks, 64.30.−t

Combining Atomic Force Microscopy and Depth-Sensing Instruments for the Nanometer-Scale Mechanical Characterization of Soft Matter

2009

Complex materials exhibit a hierarchical structure where a gradient of features on nanometer scale is induced by the synthetic route eventually enhanced by the loading condition. The nanometer scale at which individual components arrange, determining their properties, is a current challenge of mechanical testing. In this work, a survey on nanoindentation is outlined based on the comparison of results obtained by Atomic Force Microscopy and Depth-Sensing Instruments and their combination. An Atomic Force Microscope equipped with a Force Transducer gives indeed the possibility to scan the sample surface in contact mode, thereby allowing one to choose a suitable position for the nanoindentatio…

Twisting graphene nanoribbons into carbon nanotubes

2011

Although carbon nanotubes consist of honeycomb carbon, they have never been fabricated from graphene directly. Here, it is shown by quantum molecular-dynamics simulations and classical continuum-elasticity modeling, that graphene nanoribbons can, indeed, be transformed into carbon nanotubes by means of twisting. The chiralities of the tubes thus fabricated can be not only predicted but also externally controlled. This twisting route is an opportunity for nanofabrication, and is easily generalizable to ribbons made of other planar nanomaterials.

Structural and elastic properties of defect chalcopyrite HgGa2S4 under high pressure

2014

In this work, we focus on the study of the structural and elastic properties of mercury digallium sulfide (HgGa2S4) at high pressures. This compound belongs to the family of AB(2)X(4) ordered-vacancy compounds and exhibits a tetragonal defect chalcopyrite structure. X-ray diffraction measurements at room temperature have been performed under compression up to 15.1 GPa in a diamond anvil cell. Our measurements have been complemented and compared with ab initio total energy calculations. The axial compressibility and the equation of state of the low-pressure phase of HgGa2S4 have been experimentally and theoretically determined and compared to other related ordered-vacancy compounds. The pres…

Engineering in-plane mechanics of electrospun polyurethane scaffolds for cardiovascular tissue applications

2021

Effective cardiovascular tissue surrogates require high control of scaffold structural and mechanical features to match native tissue properties, which are dependent on tissue-specific mechanics, function heterogenicity, and morphology. Bridging scaffold processing variables with native tissue properties is recognized as a priority for advancing biomechanical performance of biomedical materials and, when translated to the clinical practice, their efficacy. Accordingly, this study selected electrospinning on a rotating cylindrical target as an apparatus of broad application and mapped the relationship between key processing variables and scaffold mechanics and structure. This information was…

Effects of Rastering Velocity on Electrospun Polyeurthane Structure and Mechanical Properties

2010

Hydrothermal aging of carbon reinforced epoxy laminates with nanofibrous mats as toughening interlayers

2016

Electrospun mats have been applied as toughening interlayers in high performance carbon fiber epoxy composites. While the toughening mechanism exerted by the mat at the interface is the subject of several recent studies, no investigations are reported on the aging behaviour of laminates comprising these nanostructured elements. This work investigates the influence of the combined effect of water and temperature (90 °C) on laminates with Nylon 6,6 electrospun membranes placed either at the middle plane only or at each interlayer. The water-uptake behaviour is modelled by a two-stage diffusion model and compared with the behaviour of the neat resin and of the laminate without mats. Interestin…

Testing mechanical characteristics of chestnut stakes used in bed sills for stream restoration

2017

Using of wood elements for constructing bed sills in Mediterranean streams, where the banks are not protected by tree vegetation, needs an evaluation of biological and mechanical characteristics for evaluating both the wood durability and the effectiveness of the stream restoration project. Very few studies have dealt both with the decay of mechanical characteristics of wood elements employed for stream restoration works and with the changes over time of physical and chemical wood characters. In this paper, for a wood and stone bed sill located in a stream having no shaded banks, the changes of physical and chemical characters detected after 12, 18, 24, 30, 36, 42 and 48 months on chestnut …