Effects of dopants on properties and microstructure of doped graphite

摘要

Ti doped, Si-Ti doped and B4C-Ti-Si doped graphites were developed. The influence of the dopants on the properties and microstructure of these graphites were investigated. All Ti-doped graphites have a high thermal conductivity, with the highest value reaching 285 W/mK for a concentration of 7 wt% Ti in the raw materials. Si added simultaneously with Ti promotes the growth of graphite crystals and lowers the temperature necessary to obtain high performance compared to Ti-doped graphites. A thermal conductivity up to 350 W/m K was observed for Si-Ti doped graphites. B4C-Ti-Si doped graphites have a relatively high mechanical strength while their thermal conductivities are limited to 130 W/m K. For both bi- and tri-element doped graphites, the thermal conductivity and mechanical strength decrease with increasinc, amount of Si. Almost all Si in the bi- and tri-element doped graphites was depleted during the heat treatment at 2200 degreesC, resulting in the formation of cavities. (C) 2002 Published by Elsevier Science B.V. [References: 29]