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The experimental results indicate that the Ni-ZrO2 composites synthesized with urn-sized Ni powder and nm-sized ZrO2 powder possess submicron structure. Based on the fractal theory, the relationship between the electric and thermal conductance and the chemical composition of the composites has been studied. The results show that with the increase of the nickel content, the electric and thermal conductance of the composites varies. It is proposed that in the submicron structured composites, electrons and phonons have different transport mechanisms. The electric transport in the submicron-structured composites can be attributed to the medium punch-through effect and quantum tunnel punch-through effect of electrons and the low thermal conductance is due to the phonic scattering by the submicron-sized pores, grains and grain boundaries. The reason can also be used to explain why the thermal percolation threshold value lags behind the electric percolation value. The phenomenon has been observed.
The experimental results that that the Ni-ZrO2 composites synthesized with urn-sized Ni powder and nm-sized ZrO2 powder possess submicron structures. Based on the fractal theory, the relationship between the electric and thermal conductance and the chemical composition of the composites has been studied. The results show that with the increase of the nickel content, the electric and thermal conductance of the composites varies. It is proposed that in the submicron structured composites, electrons and the phonons have different transport mechanisms. The electric transport in the submicron-structured composites can at attributed to the medium punch-through effect and quantum tunnel punch-through effect of electrons and the low thermal conductance is due to the phonic scattering by the submicron-sized pores, grains and grain boundaries. The reason can also be used to explain why the thermal percolation threshold value lags behind the electric percolation value. The phenomenon has been obse rved