M.S. Thesis Presentation by Stuart Kent Watson
Wednesday, July 26, 2000

(Dr. Jack Lackey, advisor)

"Carbon Deposition for Artificial Heart Valves Using Liquid Reagent CVD"


Artificial heart valves are manufactured by depositing a carbon and silicon carbide coating onto graphite components using a gaseous fluidized bed CVD furnace.  A gaseous reagent mixture flowing into the furnace reacts with any “hot” surfaces inside the apparatus and forms a deposit.  These surfaces include the graphite substrates, the reaction vessel walls and any particulate matter used in the fluidization process.  A disadvantage of this process is that the vessel walls and particulate matter must be cleaned and/or replaced regularly for proper operation.  Another disadvantage is that hazardous exhaust products form when depositing silicon carbide.

It is proposed that a liquid reagent CVD process be used to deposit carbon on graphite.  The graphite substrates are immersed in a liquid hydrocarbon, cyclohexane (C6H12) or benzene (C6H6), and inductively heated to initiate the deposition reaction.  The advantage is that only the substrates are coated if the reaction vessel is an electrical insulator.  It is also believed that quicker deposition rates may be realized because a large source of liquid reagent surrounds the substrate material.  In addition, the predominant exhaust product is hydrogen, which can be disposed of easily.  This thesis will describe the development of the liquid reagent CVD equipment.  In addition, it will examine the feasibility of depositing carbon on graphite using cyclohexane and benzene as reagents.  Characterization of the deposits was performed using microscopy techniques, x-ray diffraction and density and porosity measurements.