GB941795A - Improvements in or relating to permeable bodies - Google Patents

Abstract

A method of making permeable articles having fluid conducting passages therein comprises applying a porous powdered metal body to an impervious metal body and heating the bodies to produce bonding at their contacting surfaces, the impervious body being deformed either before or after the bonding operation to form passages between the two bodies. A layer of powdered <PICT:0941795/C3/1> metal 10 is applied to a metal plate 11 which has previously had a pattern of stop-weld applied to the surface, the plate and powder are subjected to a pre-sintering temperature and the metal powder compressed by rolling to the required shape prior to heating to a sintering temperature, which also produces welding of the bodies. The unwelded portions are then distended by fluid inflation or by a mandrel to form passages between the plate and the porous body. The porosity of the powdered metal body may be determined by the choice of particle size, or by including organic particles such as wood flour which combust during the sintering operation. The rolling pressure will also modify the porosity. An apparatus for continuous compressing and sintering comprises a coil of strip 11, a spray gun 19 and masks 20 which cooperate to produce the required pattern of stopweld, a hopper 14 containing powdered metal, a pair of driven rolls 13 and a sintering station 18. In an example a 3/8 inch wide layer of levigated alumina suspended in water was applied to a strip of copper 2 3/4 inches wide and 0.005 inch thick, and a layer of tin solder applied to the remainder of the plate. A 2 inches wide body, 3/8 inch thick, of sintered copper made from powder with a particle size -100 to +325 Standard U.S. mesh was placed on the plate and the assembly heated to 350 DEG F. to solder the parts together. In a second example a 1/2 inch wide layer of a graphite suspension was applied to a copper strip .010 inch thick by 1 7/8 inches wide. The same side of the strip was then coated with a thin layer of copper powder suspended in an organic laquer and the assembly sintered in hydrogen at 1800 DEG F. for 15 minutes. A second layer of copper powder 1/16 inch thick was then applied, sintered at 1600 DEG F. for 15 minutes in an hydrogen atmosphere and the compound strip then rolled to compact it slightly. The unwelded central strip was expanded by a mandrel. The pre-sintering step may be omitted. Specification 759,804 is referred to.