Multi-processes CVD / CVI vacuum furnace

Chemical Vapour Deposition (CVD) and Chemical Vapour Infiltration ( CVI) furnace

Carbon fibre reinforced composites with a matrix of carbon or silicon carbide have excellent characteristics such as low density, high strength and toughness, as well as ablation resistance at high temperature. These properties are suitable for applications such as thermal protection components in aircraft, rockets and the semiconductor industry.

To make such composites, a state-of-the-art furnace for Chemical Vapour Deposition / Infiltration . This vertical, multi- layer vacuum coating furnace is meant to deposit silicon carbide coating on the substrate using  methyl-try-chloro-silane as reactant and hydrogen as a carrying agent under suitable temperature and pressure. With minimum modifications, this CVD/CVI vacuum furnace can also be used to deposit a wide range of materials such as  boron nitride, hafnium carbide, tantalum carbide , silicon nitride and silicon dioxide .

 The double - walled, water - cooled furnace chamber of 900 mm dia  and 1050 mm height  has a demountable dished end at the bottom  and a hydraulic lifting mechanism to lift and lower the top dish. The furnace has a  hot zone of 300 mm dia  and  300 mm height , which can  accommodate a maximum  of 50 kg of material . Graphite heaters arranged in a circular fashion for resistance heating maintain anoperating temperature of 1500 deg.C in the hot zone ,  and a vacuum pumping system is  provided to achieve a vacuum of  5 x 10-2 m.bar.

A gas supply and control system  brings the gases from  bulk storage points through manifolds ,  mixes  them using  metering equipment and delivers them to the furnace  chamber. The flow of each gas  is controlled by an air actuated bellow - sealed valve and regulated by a Mass - flow controller. The MTS is regulated as a liquid and then evaporated in a heated evaporative chamber.

A Scrubber Tank consisting of PH Monitor / display control and Alarms, Automatic Level Controls and Alarms with Circulatory Pump are provided to neutralize the chemical vapors coming out from the system.  An exhaust port in the Gas Cabinet  ventilates any  gas leak without causing any risk to the operators.

A PLC enables  complete automation of vacuum  and temperature cycles . An extremely flexible SCADA software for Data Collection, Reporting and Supervisory Control is provided to carry out semi –continuous and  continuous processes in various industries.