Electrical resistivity of Cr–Al2O3 and ZrxAly–Al2O3 composites with interpenetrating microstructure
2002; Elsevier BV; Volume: 22; Issue: 13 Linguagem: Inglês
10.1016/s0955-2219(01)00539-8
ISSN1873-619X
AutoresM. Leverkoehne, V. S. R. Murthy, Rolf Janßen, Nils Claussen,
Tópico(s)Intermetallics and Advanced Alloy Properties
ResumoAC and DC resistivity of Cr–Al2O3 and ZrxAly–Al2O3 composites with varying metal content were measured. A strong percolation behavior was observed in the Cr–Al2O3 system, where the AC resistivity varied nine orders of magnitude close to the percolation threshold of 28 vol.%. AC measurements were less dependant on the contact resistance than DC measurements. The best reproducibility was obtained at a frequency of 100 kHz. AC resistivity values of insulating composites differed from DC values and may also be frequency-dependant. DC measurements up to 600 °C indicate that the intermetallic phases ZrAl3 and ZrAl are PTC conductors. The electrical properties of ZrxAly–Al2O3 samples with a metal content of 29 vol.% were anisotropic, with a much higher resistivity in the pressing direction.
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