Powder metallurgy porous material is a kind of network structure of the material from the hole communicated or closed, the hole boundary or surface composed of a pillar or tablet. The pore structure of typical: one kind is two-dimensional structure composed of a large number of polygons with holes in the plane formed by the aggregation of; because of the hexagonal structure whose shape is similar to the hive and is referred to as "honeycomb" material; the more common is the three-dimensional structure by a polyhedral shape holes in the space formed by the aggregation of, usually called "foam material. If a void solid only exists on the hole boundary (i.e. holes are interlinked), is called the hole; if the hole surface is also a solid, namely each hole and the hole around completely separated, is called the obturator; and some holes is half open and half hole closed cell.