Although much research had been conducted to improve the ability of engine cylinder heads to respond to thermal stresses, not much research had been conducted on reducing thermal stresses. The authors set out to determine the thermal conductivity of a commercial aluminum 319 type alloy cylinder head with the future goal of improving the thermal conductivity of cylinder heads to better reduce the stress induced by increasing temperature. The cylinders were ...
The authors prepared silica aerogel/polyurethane composites by two different methods for the comparison of the two methods. The objective was to study the thermal insulation and hydrophobic properties of the composites to evaluate their potential for use as fabric membranes. It was found that the composites are better thermal insulators than polyurethane alone, and that they also have improved hydrophobic properties. It was also determined that the thermal conductivities ...
Nanocomposites of polyaniline nanofibers reinforced in epoxy were prepared and their ultrasonic velocities, ultrasonic attenuations, and thermal conductivities were measured over a temperature range of 298-373 K. It was found that the ultrasonic velocity decreased with increasing temperature, but increased with increasing concentration of polyaniline nanofibers in the epoxy matrix. These two trends were opposite for the ultrasonic attenuation, and the thermal conductivity was found to increase with increasing temperature ...
The authors outline a method of enhancing the thermal properties of a paraffin phase change material through the addition of herringbone-style graphite nanofibers (HGNFs). It was found that the solid-phase thermal conductivity increased exponentially with the presence of HGNFs; however, a significant increase in the liquid-phase thermal conductivity was not observed until the concentration of HGNFs in the composite PCM reached a point above the percolation threshold. The volumetric heat ...
Various microfibrillar composites were prepared in situ using boron nitride as a thermally conductive filler. The multistage stretching extrusion process was used in an effort to improve thermal conductivity and mechanical properties. It was found that the addition of laminating-multiplying elements (LMEs) improved the dispersion of BN in the composite polymers and they also improved the tensile and impact strength of the polymers. It was also found that the thermal ...
