| 摘要 |
648,929. Powder metallurgy. MOND NICKEL CO., Ltd., and HIGNETT, H. W. G. March 25, 1948, No. 8817. [Class 83 (iv)] In a method of making highly porous metal plates, more particularly porous nickel plates for use in accumulators, the plates are built up by successively sintering a number of layers of metal powder, each layer being united to the preceding one by the sintering and without the application of pressure and being so thin that it undergoes substantially no contraction parallel to the surface of the plate during the sintering. A flat plate 3, preferably of unglazed ceramic material with a rough or corrugated surface as described in Specification 648,41.5, is supported on a rack 1 of nickel-chromium alloy which is reciprocated by a pinion 2 so that the plate is carried beneath a hopper 4 to receive a sprinkling of metal powder, then under a levelling blade 6, and through a water-cooled chamber into a sintering furnace 8. The furnace is of the high-frequency induction type and a light sintering is effected at 600‹ C. for five minutes in a hydrogen atmosphere, after which the plate 3 is carried back, through the cooler, to receive another layer of powder. When the plate is of sufficient thickness it is put on an endless belt conveyor and carried to another furnace for a final sintering at 900‹ C. for ten minutes. Other types of furnace may be used if desired. In a modification, the powder is sprinkled on to a continuous nickelchromium strip coated with a slurry of magnesia or alumina. One or more of the layers may be of a powder of different grain size in order to form a plate having different porosities at different points. |
