Characterization of synthesized nickel foam using ammonium hydrogen carbonate as space holder

• Powder metallurgy technique is still attractive in the production of nickel foam • After characterization high purity Ni-200 foam has been found with small oxidation traces • Various shapes of porosity have shown changes in compressive strength of Ni- foams • The compressive strength of Ni- foam falls to 63.3% with 80% increase in space holder concentration Nickel foam of cylindrical semi-dense structures is fabricated using powder metallurgy method and Ammonium Hydrogen Carbonate as a space holder. The samples were obtained after ball milling of both powders and uniaxial compaction of die punch. Then sintering was carried out at 1400°C for 5 hours in an inert atmosphere so that no oxidation could take place. Material characterization has been performed on the prepared three samples of Ni foam having 55%, 65 % and 75 % of Ni by weight. Subsequent X-ray Diffraction and Scanning Electron Microscopy analyses provided insights into the structural and morphological characteristics of the fabricated nickel foams. Those analysis has confirmed the presence of pure Ni in Ni-foams and no oxidation has occurred after the sintering process. Density and porosity measurements of the fabricated Ni-foams revealed a range of density from 2.53 g/cc to 5.1 g/cc having an uncertainty below 2.5 % which is quite in acceptable limit while the porosity of the samples varied between 42% and 71%, correlating with the concentration of the space holder. Compressive strengths of the samples are in the range from 56.2 MPa to 155 MPa which is inversely proportional to the concentration of the space holder. The obtained results show that the increase in the percentage of metal in Ni foam will increase the strength and density as well as reduce the porosity. However, uniform distribution of porosity and some experimental conditions have been difficult to maintain.