Porous composite sheet and process for the production thereof

A method for controlling the permeability characteristics of a sintered composite sheet comprising the steps of:

• providing a first layer comprising an A-component having a first melting temperature;
• providing a second layer comprising a B-component having voids and a second melting temperature higher than the first melting temperature;
• superimposing said first layer on said second layer to form an interface surface between said first layer and said second layer;
• selecting a sintering site distribution, a sintering temperature, and a sintering pressure based on desired permeability characteristics, said sintering temperature being greater than or equal to the first melting temperature and less than the second melting temperature;
• sintering said first layer and said second layer in said selected sintering site distribution at said selected sintering pressure and sintering temperature to thereby form sintered sites of an A/B-component at said interface surface, the A/B-component being formed by the A-component melting and flowing into the voids of the B-component while the B-component is substantially dimensionally stable;
• and
• allowing said sintered sites to cool to form said composite sheet and thereby control the permeability thereof.