Search

An ideal high performance poly(etheretherketone) (PEEK)/AlN composite that has unique combination of anisotropic linear coefficient of thermal expansion (CTE) and dielectric properties was developed for the use in electronic packaging substrate as an alternative of conventionally used epoxy/E-glass substrate. The out-of-plane and in-plane CTEs of the composites were very close to that of copper and silicon chip, respectively. The dielectric constants of the composites are almost independent with increasing frequency. The dissipation factor decreased approximately 50% compared to the pure PEEK. These results reveal that the composite may be the futuristic candidate for high performance electronic packaging substrate.

Microhardness of high performance PEEK matrix composites reinforced with micro- and nanosize ceramic particles of aluminum nitride and alumina was evaluated with Vickers hardness tester. The microhardness of composites increases with increasing ceramic particle loading. The microhardness of PEEK/AlN composites is higher than that of PEEK/Al2O3 composites. For a given volume fraction, the improvement in microhardness of nanocomposites is higher than that of microcomposites. For the first time, the Halpin–Tsai equation was applied to correlate the microhardness. It was found that the adjustable parameter, i.e. ξ, is different for both particles. The value of ξ is higher for nanocomposites compared to microcomposites, © Elsevier

Modified Al (7010) matrix composites with 0-15 wt.% dispersion;; of SiC particles (∼7 μm) have been developed by powder metallurgy route. The processing route involved attritor milling of Al, Zn, Mg, Cu and SiC powders blended with 2% stearic acid to accomplish mechanical alloying and dispersion of SiC. The process of mechanical alloying was monitored by image analysis and XRD. It was found that mechanical alloying to the extent of 50-75% was achieved in 12 hours of attritor milling. With the help of DSC the hot pressing condition (565°C under 110 MPa for 2 minutes) was fixed in such a way that it led to completion of the remaining alloying of the constituent elements and also high densification (porosity < 1%). The particulate strengthening by SiC has been found to be quite effective in increasing the Brinell hardness (134 to 191 kg/mm2) and in retaining a high tensile strength at 300°C.

High performance nanocomposites were prepared by incorporating 0–12 vol.% nano-sized (39 nm) Al2O3 particles into PEEK matrix using compression molding. The microhardness and dynamic mechanical properties of the nanocomposites increase with increasing Al2O3 content. The wear resistance of the nanocomposites evaluated at a sliding speed of 1.0 m/s and nominal pressure from 0.5 MPa to 1.25 MPa under dry sliding conditions was improved more than threefold at 0.8 vol.% Al2O3 content. However, the wear resistance of the nanocomposites containing above 1.67 vol.% Al2O3 was deteriorated, despite their higher hardness and stiffness as compared to that of nanocomposites containing lower Al2O3 content. The surface roughness of the wear track formed over the countersurface increases with increasing Al2O3 content. The coefficient of friction of nanocomposites was higher than that of pure PEEK. SEM and optical microscopy have shown that wear of pure PEEK occurs by the mechanism of adhesion mainly, whereas of nanocomposites by microploughing and abrasion. Energy dispersive spectrometry (EDS) shows that Fe and alloying elements of countersurface transfer to the wear debris at higher Al2O3 content., © Elsevier