The production of open cell Ni-foam using KBr as spacer and oxidation shield via powder metallurgy technique

Abstract

Metallic materials having a porosity of 70% or more are generally referred as highly porous metals. In this study, highly porous pure nickel materials were produced by powder metallurgy route. In the production process, potassium bromide was used both as a space-holder phase and as an oxidation shield. In the method, firstly, nickel and potassium bromide powders were mixed according to the desired void ratio. The obtained nickel-potassium bromide powders were pressed in a hydraulic press and turned into pellets (diameter: 13mm). Then, these pellets were pressed again in a wider mold (diameter: 21mm) so that all surfaces were covered with potassium bromide, and the encapsulation process was carried out. These capsules were embedded in potassium bromide in an alumina crucible for sintering. The sintering process was carried out in an open atmosphere at 1050 °C for 60 minutes. After the sintering process, the crucibles were kept in water to dissolve the crystallized potassium bromide around and inside the sample. Density, macrostructure, microstructure and EDS analyzes were performed on the samples. It was observed that open cell pores (58.3 - 78.1% vol) with diameters varying between 5 and 500 µm, which are homogeneously distributed in nickel, have been successfully obtained. In addition, it was proved that nickel foam materials can be produced in different sizes and designs.

Keywords

• High Porosity;
• Molten Salt shield
• Nickel Foam;
• Potassium Bromide
• Powder Metallurgy

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