W‐Cu Throat Inserts for Missile Applications

Copper infiltrated tungsten composites are used for different missile components such as jet vanes, throat nozzles and throat inserts that are used as altitude controls in thrusters of various missiles. The composites are prepared by sintering of pure tungsten powders in order to obtain a controlled level of interconnected porosity followed by infiltration of molten copper into the porous mass.

Salient Features of Technology Developed at DMRL

DMRL has developed a process to manufacture W‐Cu throat inserts and optimized the numerous process parameters such as initial tungsten purity, particle size, green density of tungsten compact, sintering temperature, sintering time, sintered density, purity of copper, infiltration temperature, infiltration time and machining parameters etc. The optimised process has resulted in defect free W‐Cu composite.

Advantages of DMRL Process

• Saves power & money due to low infiltration temperature
• Defect free product
• Improved machinability
• Improved yield

To realise a pore free uniform product, a new process was adopted using the graphite dies for infiltration and refractory metal powder for packing. The process achieved pore free composite with good machinability and significantly improved yield. The components passed non destructive tests and showed satisfactory performance under static tests in RCS thrusters.

Properties of W‐Cu Composite

The W‐Cu composite has shown excellent erosion resistance and has helped in achieving consistent pressure chamber for 50 seconds of firing duration.

Typical room temperature mechanical properties of the W‐Cu composite

Applications

• Defence Applications:    Jet Vanes, Throat Nozzles, Throat Inserts
• Civilian Applications:    Electrical Contacts, Resistance Welding Contacts, Electrical Discharge Machining (EDM) Electrodes, Porous Emitters