Improvements in and relating to methods of producing porous metallic tubes

摘要

A porous metallic tube such as nickel is produced by extruding a mixture of the metal powder and a binder such as paraffin present in a volume equal to the pore volume of the compacted powder metal, the extruded tube being packed in an inert powder such as alumina, graphite or magnesium silicate which is lightly compacted prior to sintering so that the powder in the bore of the tube prevents radial shrinkage. The metal powder has a particle size of 1 to 500 micron and in an example carbonyl nickel powder is mixed with 20% of binder and after extrusion the tubes are packed in alumina of 30 micron size. Sintering is effected at 850 DEG C. in hydrogen and the sintered tubes had a porosity of 45%.