Diffusion

· In some products, such as metal filters or plane bearings, the connected pores are part of the product design. The photographs show a filter at two magnifications and display the neck formed between the particles in the sintering process.
· This neck structure is a stage in the diffusion bonding of even dense parts.
· For use as a plane bearing, the pores shown would be filled by a lubricant that would be released over the lifetime of the component.

From: Edwards & Endean, "Manufacturing with Materials," Butterworths (1990)