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Shock waves in basalt rock generated with high-powered lasers in a confined geometry (1999)

Bolger, J. A. ; Montross, C. S.

[S.l.] : American Institute of Physics (AIP)

Journal of Applied Physics 86 (1999), S. 5461-5466

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Details

ISSN: 1089-7550

Quelle: AIP Digital Archive

Thema: Physik

Notizen: An investigation was made into the interaction of Q-switched Nd: glass laser pulses, with energies of 5–100 J and intensities in the range of 1–15 GW cm−2, with thin slab samples of basalt, in a geometry in which the laser–matter interaction was enhanced by confining the laser-induced plasma and vapor against the rock surface with a thin water layer. The high pressure generated during expansion of the ablated material produced a shock wave which traveled into the rock. On basalt samples of thicknesses of up to 18 mm, reflection of the shock wave at the rear surface of the sample caused a thin rock layer to be spalled. Examination of the structure within the interior of the rock after laser exposure revealed extensive grain disruption near to the laser spot, due to the shock-wave passage. Rock specimens of thickness 50 mm were tested via Vickers hardness microindenter. The laser exposure was shown to produce a hardness decrease within the rock which was up to 50%, and extended to depths of 25 mm beneath the target position. An empirical model accounting for shock-wave formation and propagation was developed and compared to the experimental results. © 1999 American Institute of Physics.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.371546

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Digitale Medien

Conductivity and strength behaviour of aluminawhisker-zirconia composites (1995)

Montross, C. S. ; Hassel, B. A. ; Kawada, T. ; [weitere]

Springer

Journal of materials science 30 (1995), S. 3285-3290

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ISSN: 1573-4803

Quelle: Springer Online Journal Archives 1860-2000

Thema: Maschinenbau

Notizen: Abstract Yttria stabilized zirconia (8 mol%) composites were fabricated by tape casting with either alumina powder or alumina whiskers, and pressureless sintered. Sintering behaviour, ionic conductivity and mechanical strength were analysed. For all compositions analysed, increasing alumina content reduced the sintered density. For whisker-reinforced zirconia, the rigid whiskers prevented matrix densification along their axis. The ionic conductivity was measured by the complex impedance method from 500–1000 °C and the activation energy for ionic conduction calculated over that range. The ionic conductivity of the alumina-zirconia composites decreased with increasing alumina content as expected by the rule of mixtures. However, the ionic conductivity of the whisker-zirconia composites decreased more than expected possibly due to contamination from the whiskers. The strength of the whisker-zirconia composites was also found to be affected by the porosity. At 5 vol%, the average strength was measured at 39.9 kgf mm−2, which decreased to 24 kgf mm−2 at 20 vol%.