Effects of residual chlorine on properties of carbide derived carbon

A novel carbon coating film-Carbide Derived Carbon (CDC) has been produced by selectively etching the metal species from carbide in chlorine containing environment. A consequence of synthesizing CDC in chlorine is the presence of residual chlorine in the material. Residual Chlorine is detrimental to biocompatibility of the material, and may affect the physical properties of CDC. A systematic study of residual chlorine and its effects on CDC properties has been conducted in this thesis.;Accurate quantitative analyses are provided by WDS analysis. Chlorine is present in CDC synthesized from all metal carbides tested. A gradient in chlorine content increasing from the CDC/SiC interface to the CDC/gas interface was observed by EDS, suggesting that diffusion of chlorine in CDC is the rate controlling mechanism for growth of the CDC layer.;Hydrogen post-treatment at 800°C for 8 hours in flowing Ar-5% H 2 removes residual chlorine from CDC synthesized in Cl2/Ar mixture. However, when CDC is synthesized in Cl2/HCl mixture, XPS analysis shows that the chemical bonding of the residual chlorine differs from that produced in Cl2/Ar mixture, and this chlorine is more difficult to remove by subsequent hydrogen treatments. Chlorine in CDC influences the tribological performance of the coating, particularly in humid environments. Tribological performance of CDC produced is Cl2/Ar mixtures is improved by hydrogen post-treatment, while less effect is observed for CDC: produced in Cl2 with hydrogen.;Recalculation of the hydrogen storage capacity shows that about 1.2wt % of hydrogen can be stored in CDC derived from Ti3SiC2 at room temperature and 1 M Pa. Therefore hydrogen storage capacities in the range of 6% could be achievable at modest pressures in the range of 5 MPa.