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Abstract: Transparent SiO2 bodies were prepared by pressureless sintering (PLS) and spark plasma sintering (SPS). The effects of sintering and annealing temperature on the transmittance of the SiO2 bodies were investigated. The SiO2 bodies sintered by SPS and PLS at 1073–1573K were amorphous. With increasing the sintering temperature to 1673K, the SiO2 bodies sintered by PLS were crystallized while those sintered by SPS were still amorphous. The relative density of the SiO2 bodies sintered by SPS was 98.5% at 1373K and 100% at 1573K, whereas that sintered by PLS was 92.6% at 1373K and 98.9% at 1573K. The transmittance was 91.0% and 81.5% at a wavelength (λ) of 2μm for the SiO2 sintered bodies by SPS and PLS, respectively. In the ultraviolet range, the transmittance of the SiO2 bodies sintered by SPS at 1573K was about 40% at λ =200nm and increased to 75% after annealing at 1073K for 1h, which was about three times of the transmittance of the SiO2 bodies sintered by PLS (24.8%). [Copyright &y& Elsevier]

The sliding wear properties of high-velocity oxygen-fuel (HVOF) sprayed nanostructured WC-CoCr cermet coatings against Al 2 O 3 under dry friction at different temperatures were investigated using a pin-on-disk high-temperature tribometer. The microhardness data of the coatings were also statistically analyzed by using the Weibull distribution. The results showed that nanostructured coatings exhibited a mono-modal distribution under indentation load of 100 g, and a bimodal distribution under indentation load of 300 g. With increasing test temperature, the coatings showed an increase in wear rate. The evolution of the sliding wear mechanism of the coatings with the increase of the temperature was extrusion deformation at room temperature, carbide particle pull-out, oxidation wear and adhesive wear at 200 °C, and a combination of binder extrusion and fatigue delamination coupled with oxidation wear at 500 °C. [ABSTRACT FROM AUTHOR]