Verfahren zur Herstellung von Gegenstaenden aus pulverfoermigen Materialien

摘要

In a method of hot pressing powders such as carbides, borides, nitrides, silicides of metals of Group IV-V1, BeO, MgO, ZnO2, Al2O3 and cermets, the powder is changed into an open ended container which may be preheated, prior to loading into the hot pressing die which is at the required sintering temperature, hot pressing is then carried out and the container and sintered compact is discharged. The process may be used for semi continuous or continuous hot pressing. Examples are given of the hot pressing of the following materials: SiC, TiB2, mixtures of TiB2 + TiC, mixtures of Cu + TiB2, BN and Al2O3. For the semi continuou process the powder is packed into sleeve dies which fit closely into the hot press die. Graphite pads are placed at either end and pressure is transmitted via plungers. (Figure 4 not shown). For continuous hot pressing (Figure 5) several powder charges in sleeve dies 54 are loaded into the die 38 with graphite pads 52 of adjacent sleeve dies separated by plungers 60 with a spacer 53 therebetween. The die is surrounded by a resistance furnace comprising a carbon resistor, a graphite sheath and lampblack (Fig. 2 not shown) and the furnace is purged with argon or nitrogen prior to hot pressing. The hot press die is charged at one end, pressure is exerted and the pressed compacts are removed at the other end, fresh charges being continuously loaded at the feed end. The sleeve dies may be lubricated with petroleum jelly and graphite prior to changing with powder.