Wear and scuffing resistances of eutectic aluminum-silicon alloys and aluminum-silicon based composites

The existing information in the open literature suggests that the eutectic Al-Si alloy may be one of the best candidate materials for the sleeveless automotive engine block application. Dry sliding wear tests have been conducted using the block-on-ring wear machine on the near eutectic Al-Si alloys (13.2% Si) with the same chemical compositions, in which two were as-cast alloys had needle-shape Si particles, and the other two T6 heat treated alloys had round-shape Si particles. The T6 heat treatment has efficiently improved the hardness of the Al matrix, refined the Si particles in comparison to the as-cast alloys. The reciprocating wear tests were performed on the as-cast alloys and the T6 heat treated alloys at engine operating temperatures and lubricated conditions. An systematic investigation of the effect of Si particle morphology and strength of Al matrix on the wear behaviour of the near eutectic alloys has been carried out using single pass scratch test supported by microhardness measurements, optical microscopy (OM), scanning electron microscopy (SEM), EDS and optical surface profilomety (Wyko) investigations. (Abstract shortened by UMI.) Source: Masters Abstracts International, Volume: 44-03, page: 1480. Thesis (M.A.Sc.)--University of Windsor (Canada), 2005

Quantitative calculations of the excitonic energy spectra of semiconducting single-walled carbon nanotubes within a π\pi-electron model

Using Coulomb correlation parameters appropriate for $\pi$-conjugated polymers (PCPs), and a nearest neighbor hopping integral that is arrived at by fitting the energy spectra of three zigzag semiconducting single-walled carbon nanotubes (S-SWCNTs), we are able to determine quantitatively the exciton energies and exciton binding energies of 29 S-SWCNTs within a semiempirical $\pi$-electron Hamiltonian that has been widely used for PCPs. Our work establishes the existence of a deep and fundamental relationship between PCPs and S-SWCNTs.Comment: 6 pages, 2 figures, 2 table