Gabriele Steinborn

Influence of the dispersants in gelcasting of nanosized TiN

Abstract The gelcasting process for shaping of plasma synthesized nanosized TiN with regard to the dispersion behaviour and the resultant microstructures has been investigated. The dispersion behaviour of the powder and rheology of the slurries under the influence of three different dispersants have been studied as a function of pH. Solid content of the slurries was up to 22 vol%. The isoelectric points as measured by the streaming potential method were found to be at a pH of 3.7 and lower. Sintering of the dried and debindered green bodies was carried out in a N 2 atmosphere with the application of 50 bar gas pressure in the final sintering stage leading to densities of 95.5%. Resulting microstructures are strongly dependent on the dispersant used.

Joining of Ceramic Components in the Green State via LPIM

It has been successfully demonstrated that ceramic materials can be joined in the green state without a second phase by using low pressure injection molded parts. The investigation of the joining interface revealed that a high quality interface can be achieved by carefully adjusting the different manufacturing steps. The use of monomodal particle size distribution in the used powder CT3000SG is inferior to a broader particle size distribution obtained by replacing 33% of the finer alumina powder by coarser CT1200SG. In this way the dewaxing process is significantly improved when the wall thickness of the part exceeds 3 mm. The investigation of the mechanical properties of the joined and sintered parts revealed, that the bending strength of the joined specimens achieved about 80 % of the unjoined, monolithic specimens.