an epoxy resin was modified by silica nanoparticles and cured with an anhydride. the particles with different batches of 12, 20, and 40 nm sizes were each distributed into the epoxy resin ultrasonically. electron microscopy images showed that the silica particles were well dispersed throughout the resin. tensile test results showed that young’s modulus and tensile strength increased with the vo...

Mechanical alloying and vacuum sintering have been used to produce bulk nanostructured Ti5Si3 and Ti5Si3-15Wt.% Al2O3 nanocomposite. X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) were used to study the microstructural characteristics of the samples. Indentation method was used to calculate hardness, elastic modulus and fracture toughness ...

Mineralized collagen fibrils are composed of tropocollagen molecules and mineral crystals derived from hydroxyapatite to form a composite material that combines optimal properties of both constituents and exhibits incredible strength and toughness. Their complex hierarchical structure allows collagen fibrils to sustain large deformation without breaking. In this study, we report a mesoscale mod...

Bioactive ceramics have received great attention in the past decades owing to their success in stimulating cell proliferation, differentiation and bone tissue regeneration. They can react and form chemical bonds with cells and tissues in human body. This paper provides a comprehensive review of the application of bioactive ceramics for bone repair and regeneration. The review systematically sum...

Mineralization is a typical strategy used in natural materials to achieve high stiffness and hardness for structural functions such as skeletal support, protection or predation. High mineral content generally leads to brittleness, yet natural materials such as bone, mollusk shells or glass sponge achieve relatively high toughness considering the weakness of their constituents through intricate ...

The effect of prepolymerized particle fillers on fracture toughness of four commercial composite resins was studied. The ground surface morphology was examined with a field emission scanning electron microscope. Fracture toughness was determined by using single edge notched specimens. Acoustic Emission (AE), which is the elastic wave due to the release of energy from the localized sources of ma...

The conflict between strength and toughness is a long-standing challenge in advanced materials design. Recently, a fundamental bottom-up material design strategy has been demonstrated using cellulose nanopaper to achieve significant simultaneous increase in both strength and toughness. Fertile opportunities of such a design strategy aside, mechanistic understanding is much needed to thoroughly ...

The effect of microstructural variations on the fracture toughness of Alloy 718 was reviewed. The metallurgical parameters surveyed in this paper included heat treatment, heat-to-heat variations, product-form variations, neutron irradiation and long-term thermal aging. Key microstructural features and operative fracture mechanisms were related to macroscopic fracture toughness properties.

Natural structural materials such as bone and seashells are made of relatively weak building blocks, yet they exhibit remarkable combinations of stiffness, strength and toughness. This performance can be largely explained by their ‘‘staggered microstructure’’: stiff inclusions of high aspect ratio are laid parallel to each other with some overlap, and bonded by a softer matrix. While stiffness ...

The fracture toughness and uniaxial tensile yield strengths of unmodified and CTBN-rubbermodified epoxies were measured under hydrostatic pressure. The purpose of these experiments was to learn how suppressing cavitation in rubber particles affects the deformation mechanisms and the fracture toughness of rubber-modified epoxy. It was found that the cavitation of CTBN-rubber could be suppressed ...