Sharif Digital Repository

In recent years, carbon nanotubes have been the focus of considerable researches. Numerous investigators have reported remarkable physical and mechanical properties for this new form of carbon. In particular, the exceptional mechanical properties of carbon nanotubes, combined with their low density, offer scope for the development of nanotube reinforced composite materials. The potential for nanocomposites reinforced with carbon tubes having extraordinary specific stiffness and strength represent tremendous opportunity for application in this century and recently metal matrix type of these nanocomposites, due to their advantages, have received great attention. Classical theories of... 

Nanocomposites are fabricated by incorporating nano-scale particles in polymer, metal, or ceramic matrices. Metal matrix nanocomposites are a new kind of materials which have shown superior mechanical features, such as high strength, stiffness, and hardness. However, they are not sensitive to high temperature, in contrast to the polymer matrix nanocomposites. Nanoporous materials, also, have wide range of applications in different fields, such as geology, biology, biomechanics, and electronic. Carbon Nanotubes (CNTs) have shown wonderful properties like high Young’s modulus, high resonance frequency and unique electrical behavior. Wonderful mechanical and electrical properties make CNTs... 

Nowadays, metal matrix composites due to their magnificent properties, has met diverse applications in automobile, aerospace and military industries. Decreasing the reinforcement size from micro-meter to nano-meter, properties of these structures will be improved significantly. Better properties will lead to better applications for them in the future. Thus, the main objective of the current project was investigation on the mechanical properties of metal matrix nanocomposites produced with shock wave sintering. In order to gain this aim, first the sintering of nanoparticles was modeled. A new model was proposed to consider the neighboring particles effects. Using the model, sintering of many... 

Using materials with better mechanical properties is always advantageous. Many sectors, including automotive and aerospace industries, are always seeking new materials with better mechanical properties and lower weight. A lighter vehicle means lower emission and higher fuel efficiency. Thus, developing new methods to investigate novel materials is very important. One of these novel materials are Metal Matrix NanoComposites (MMNCs). MMNCs are fabricated using nano scale particles embedded in metallic matrix. High strength, stiffness, and hardness are the three most important mechanical properties of MMNCs. Introducing a suitable way of modeling these materials is important since it will... 

In this study, Al6063-Al203 nanocomposite powders were synthesized by reaction mechanical milling method. Nanometric reinforcement particles were formed via high- energy ball milling under a controlled oxygen containing atmosphere. Morphological and microstructural evolutions of nanocomposite powders were investigated by using X-ray diffraction (XRD), thermal analysis (DTA), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) methods at different milling times. The results showed that mechanical milling stages were accelerated and the time for reaching steady- state condition was decreased by an increase in the oxygen content in the milling atmosphere. The in-situ... 

In this research, aluminum titanate or tialite with the chemical composition of Al2TiO5 was synthesized as nanostructured form using the sol-gel method with the aim to serve as a chemical source for aluminum and titanium elements within the fabrication of in-situ Al2O3-Al3Ti-reinforced aluminum matrix nanocomposites. Since the aforementioned nanocomposite is produced based on the thermal decomposition of tialite, the thermar decomposition of this material in air atmosphere, under applied mechanical strain, and direct contact with the underlying aluminum was comprehensively evaluated. The empirical results showed that as tialite is exposed to aluminium, the reaction starts from low...