Fabrication of porous molybdenum by controlling spray particle state

In this study, porous molybdenum (Mo) was prepared by flame spraying of semi-molten particles with low velocity. The influence of spray particle parameters, including velocity and melting degree, on the microstructure and porosity of Mo deposit was investigated to understand the formation mechanism of the pore structure and connection between particles. The results showed that Mo spray particles with low velocity (<20 m/s) and semi-molten state can be generated by flame spraying. The Mo deposits with porosity from 39 to 61% were produced. High porosity in the deposit was achieved through the shielding effect of deposited particles. The surface-molten particles were bonded by the melt which flowed from surface to the particle/particle contact area. Moreover, the porosity decreased with the increase of melting degree of particles before impact. A 2D stacking model of semi-molten particles was proposed to explain the formation of bimodal pores and high porosity.