Study of physical characteristics of nickel wicks developed by metal injection moulding

Abstract

The present research is focused on porous, grooved and tubular wick development. The basic purpose of a wick is to generate capillary pumping pressure for circulation of a working fluid within the loop heat pipe, which is used in spacecrafts and satellites. The present work establishes metal injection moulding as a potential route for wick development in the near net shape form. Nickel powder, polypropylene powder and thermoplastic binder have been used to produce green compacts of the wicks before sintering. Experiments have been performed at three levels of sintering temperature (900, 930 and 950°C) and sintering dwell time (30, 60 and 90 min). Optimum sintering condition has been found in this work as 900°C temperature and 60 min time, which gives optimal values of porosity (55 vol.-%), average pore diameter (2·6 μm), permeability (1·94×10⁻¹² m²), effective thermal conductivity (9·37 W m⁻¹ K⁻¹) and average capillary pumping pressure (54 kPa) in the wick.

Keywords:

• Ni powder
• Porous wick
• Loop heat pipe
• MIM
• Capillary pressure

The authors would like to thank Professor (Dr) G. Biswas, Director, CMERI, Durgapur, for his continuous encouragement to carry out this research work. The authors would like to acknowledge with thanks Dr A. Ambiaranjan, Scientist, ISRO Satellite Centre, Bangalore, and Dr K. Singh, Scientist, CSMCRI, for their technical support during execution of this work. Thanks to the members of the Foundry Group of CMERI for their help and support in this work.