A novel approach of manufacturing Nickel Wicks for loop heat pipes using Metal Injection Moulding (MIM)

Abstract

Sintered nickel powder is proposed to be used as porous wicks in loop heat pipes used for space applications such as satellites and space crafts. In this work, the manufacturing procedure for tubular wicks through novel Metal Injection Moulding (MIM) route is discussed. Nickel powder, Polypropylene powder and thermoplastic binder are used to produce feedstock for injection moulding. Ideal sintering condition identified as 900°C and 60 minutes. Porosity, pore diameter of the wicks are evaluated by geometric measurements using an electronic weight measuring machine and a micrometer and extrusion flow Porosimeter, respectively. Permeability was calculated according to the Carmen-Kozeny equation. Experimental finding shows that porosity level of 55 vol%, average pore diameter of 2.6 μm, permeability of 1.94 × 10-12 m2 and roundness of 5% have been achieved in the porous wick. SEM investigation of pore structures shows the presence of large pores which leads to enhanced porosity and interconnected fine pore network responsible for generation of required capillary pumping pressure. © 2013 Indian Academy of Sciences.