Since the past decade, rapid development in nanotechnology has produced several aspects for the scientists and technologists to look into. Nanofluid is one of the incredible outcomes of such advancement. Nanofluids (colloidal suspensions of metallic and nonmetallic nanoparticles in conventional base fluids) are best known for their remarkable change to enhanced heat transfer abilities. Earlier research work has already acutely focused on thermal conductivity of nanofluids. However, viscosity is another important property that needs the same attention due to its very crucial impact on heat transfer. Therefore, viscosity of nanofluids should be thoroughly investigated before use for practical heat transfer applications. In this contribution, a brief review on theoretical models is presented precisely. Furthermore, the effects of nanoparticles' shape and size, temperature, volume concentration, pH, etc. are organized together and reviewed.

A review of various properties of ceramic-reinforced aluminium matrix composites is presented in this paper. The properties discussed include microstructural, optical, physical and mechanical behaviour of ceramic-reinforced aluminium matrix composites and effects of reinforcement fraction, particle size, heat treatment and extrusion process on these properties. The results obtained by many researchers indicated the uniform distribution of reinforced particles with localized agglomeration at some places, when the metal matrix composite was processed through stir casting method. The density, hardness, compressive strength and toughness increased with increasing reinforcement fraction; however, these properties may reduce in the presence of porosity in the composite material. The particle size of reinforcements affected the hardness adversely. Tensile strength and flexural strength were observed to be increased up to a certain reinforcement fraction in the composites, beyond which these were reduced. The mechanical properties of the composite materials were improved by either thermal treatment or extrusion process. Initiation and growth of fine microcracks leading to macroscopic failure, ductile failure of the aluminium matrix, combination of particle fracture and particle pull-out, overload failure under tension and brittle fracture were the failure mode and mechanisms, as observed by previous researchers, during fractography analysis of tensile specimens of ceramic-reinforced aluminium matrix composites.

Nanofluids are suspension of highly conductive nano‐sized particles in conventional fluids that may be applicable as ultrafast cooling agent to extend the thermal performance of cooling devices. However, before considering the feasibility as coolant for high heat flux components, a thorough investigation of the long‐term stability of nanofluids is of paramount importance. Preparation of extremely stable nanofluids has become one of the main technical challenges. The present contribution aims to summarize the recent developments in the preparation, characterization, and stabilization of nanofluids based on the information available in literatures. Lastly, existing needs and attainable solution to challenges, leading to the upcoming research in the development of highly stable nanofluids, are discussed.

Ceramic-reinforced aluminium matrix composites have attracted considerable attention in engineering applications as a result of their relatively low costs and characteristic isotropic properties. Reinforcement materials include carbides, nitrides and oxides. In an effort to achieve optimality in structure and properties of ceramic-reinforced metal matrix composites (MMCs), various fabrication and heat treatment techniques have evolved over the last 20 years. In this paper, the status of the research and development in fabrication and heat treatment techniques of ceramic-reinforced aluminium matrix composites is reviewed, with a major focus on material systems in terms of chemical compositions, weight or volume fraction, particle size of reinforcement, fabrication methods and heat treatment procedures. Various optical measurement techniques used by the researchers are highlighted. Also, limitations and needs of the technique in composite fabrication are presented in the literature. The full potential of various methods for fabricating ceramic-reinforced aluminium matrix composites is yet to be explored.

No abstract