| abstract |
The invention relates to a method for producing hollow bodies having freely displaceable particles enclosed in the hollow body, wherein a) a gel-forming liquid in which the particles are suspended is brought into a cross-linking bath, b) the gel cores that form are isolated, c) the cores are coated with a composition comprising sinterable material and a binder, and d) the coated cores are subjected to a heat treatment wherein the gel and the binder are expunged and the sinterable material is sintered into a closed shell. The gel forming material is, for example, sodium alginate, and the cross-linking bath comprises calcium ions. The particles are selected, for example, from ZrO 2 , Al 2 O 3 , TiO 2 , and SiO 2 or mixtures thereof. The sinterable material is, for example, a metal powder such as carbonyl iron powder. |