The preparation of highly porous structures from filamentary nickel powders

Porous nickel structures are in high demand for battery, catalyst and filter materials applications. Traditionally such structures are made by sintering fine filamentary nickel powders. However, the strength of such structures is rather low, when compared, for example, with Ni foams of similar density. In this research we have applied colloidal processing techniques to improve the powder particle distribution and, hence the strength of the final sintered structure. By dispersing Ni powder in water prior to introducing a binder, better separation of particles and break-up of conglomerates is achieved. The addition of dispersants further improves the particle distribution. The new method also enhances control of the slurry viscosity and the green density of the nickel porous body. The structure of battery plaque prepared according to the new technique is therefore more uniform than the structure of the conventional plaque. Moreover, the tensile strength of a plaque prepared by the new method is increased by 50–70%.