Carbide Derived Carbon

Prateek Gupta and Chris White, PhD Candidates, Advisor: Dr. Michael J. McNallan

Carbide derived carbon (CDC) is a novel material that has been the subject of a great deal of research within the last decade. CDC forms on the surface of a metal carbide by selectively etching the metal from the carbide, usually with a halogen at high temperature. The remaining material is a carbon mesh that consists of various carbon structures, such as diamond onions, graphite, carbon nanotubes and amorphous carbon. Since CDC has a low friction coefficient in sliding contact, and does not easily delaminate from the surface of the carbide, one set of applications that CDC has advantages over other coatings in tribological applications. Another set of applications where CDC can be useful are those that require materials with high specific surface area. CDC is a viable material for such applications since CDC is known to have a high specific surface area with a tunable porosity.
Prateek-GuptaMy research is focused on CDC behavior in different chemical environments. Particularly I am interesting in the adsorption of water onto CDC. CDC is an extremely hygroscopic material, being able to adsorb a significant amount of water from low relative humidity air. Understanding how and why water is adsorbed onto CDC is extremely important for both the synthesis of CDC as well as for its application.

In my work, CDC layers were synthesized on SiC and were exposed to controlled water vapor atmospheres, so that the effects of water vapor pressure on the absorption could be quantified. The isotherms that came from the experiments yielded insights as to the nanostructure when the sample is synthesized. Also the isotherms show that the sample conditions affect the response of the CDC to hydrogen treatment after synthesis. Our data suggests that if the sample is saturated with water before a hydrogen treatment, the CDC will change from having a microporous structure, to a macroporous structure after hydrogen treatment. Also the specific surface area of the CDC will decrease after hydrogen treatment if the CDC is saturated with water before the post treatment occurs.

Fellow PhD candidate, Chris White, has been working on improving the physical and mechanical properties of CDC. While other means of depositing carbon layers currently exist, they often are associated with processing conditions that require relatively expensive overhead costs. CDC synthesis offers a low cost alternative for synthesis of a friction reducing coating. UIC currently holds a patent for the basic CDC formation from metal carbides that is the basis for at least one new start-up company. White’s work focuses on introducing Hydrogen to the CDC matrix either during synthesis of the CDC, as a secondary post treatment or both. This work has shown great improvement in reducing the already good frictional qualities of CDC. Beyond lowering the coefficient of friction of CDC, current research is focused on analyzing how the addition of Hydrogen affects the overall wear of CDC in tribological applications. This work has great promise for commercial uses and is likely to enter into the market as a production enhancement of CDC applications in the near future.