Conductive Property of Recrystallized Graphite Doped with Titanium and Silicon

The bi-element doped recrystallized graphite was prepared from calcined coke, coal-tar pitch, titanium and silicon by a hot-pressing process in order to investigate the effects of the amount of dopants on the thermal conductivity, electrical resistivity, bending strength and microstructure. Experimental results show that the basic physical properties of recrystallized graphite with 15wt% of dopant titanium are improved greatly, compared with pure graphite prepared by the same process. The thermal conductivity of recrystallized graphite with 15wt% of titanium and less than 2wt% silicon increases with increasing the amount of silicon at ambient temperature. The thermal conductivity of RG-TiSi-152 with 15wt% titanium and 2wt% silicon is 494W/m-K. The thermal conductivity of bi-element doped recrystallized graphite with 15wt% titanium and more than 2wt% silicon decreases with increasing the amount of silicon at ambient temperature. The electrical conductivity and bending strength of silicon and titanium doped recrystallized graphite decrease with increasing the amount of silicon. XRD analysis indicates that titanium added to carbon substrates exists in the form of TiC precipitates and much of silicon added to carbon substrates will escape from the material at last. The layers spacing d002 and coherence length La of RG-TiSi-152 are 0.3355 nm and 864nm, respectively.