Development of tungsten-copper composite for bi-propellant control thrusters

This paper describes the development, fabrication and testing of tungsten-copper composite material for the specific use as nozzle throat insert in the bi-propellant reaction control thrusters based on Red Fuming Nitric Acid (RFNA) and Hydrazine (N2H4). The fabrication process consists of infiltration of copper into sintered porous tungsten matrix which is later machined to desired shape. The tungsten-copper composite material thus developed is evaluated in an arc-jet facility with an aim to ptimise composite composition based on heat flux prior to carrying out qualification test with proto thruster. The performance of throat inserts is found to depend not only on the microstructure and the composite density but also on the parameters of the thruster and injector design as well. The erosion of the nozzle throat insert, observed after the static firing of the bi-propellant engine is sought to be explained in terms of microstructure, transpiration cooling and injector design. Composite density of 16.85+0.1 g/cc has been found to meet the designed requirement of control thruster of our launch vehicle programmes.