Patent Number: 043839444
Section: description

EXAMPLE Glass balls less than 2 mm in diameter were mixed with lead powder which was sedimentatively matched by way of a determination of its powder characteristic (e.g. particle size and shape, chemical composition, microstructure and particle density), i.e. the mixing was done in a liquid whose viscosity was variable as for example glycerin and alcohol in variable concentrations. The suspension of glass and lead in liquid was disposed in a mixing vessel which was moved in a tumbling mixer for about 3 hours, until a macroscopically homogeneous distribution of the two powders in the suspension had been achieved. Due to the sedimentatively matched similar sinking speeds, this distribution remained the same even after the powders settled in the suspension. The liquid was next evaporated at sufficiently low temperatures to avoid oxidation of the lead, which was minimized. The mixture was then pressed in steel molds at about 100 Newtons/mm.sup.2 compression pressure avoiding excessive pressure which would cause the resulting molded balls to burst. Finally, the pressed mixture was sintered at about 400.degree. K. for about 5 hours. In this example, the mixing ratio of volume of lead : volume of glass was equal to 7:1. The strength of the resulting molded bodies was good, and their diameter was 2 cm. It will be understood that the above description of the present invention is susceptible to various modifications, changes and adaptations, and the same are intended to be comprehended within the meaning and range of equivalents of the appended claims.