Authors: O.L. Khasanov, E.S. Dvilis, V.M. Sokolov, Yu. Pokholkov and G. Loutts
Affilation: Tomsk Polytechnic University, Russian Federation
Pages: 23 - 26
Keywords: nanopowder, dry pressing, ultrasonic vibrations, net-shaping
The work aim is development of methods of dry nanopowder uniform compacting into complex shapes for sintering nanostructured ceramics and composites. In processing of bulk nanoceramic articles, it is important to compact nanopowder into a required shape having uniform density without gradients of internal stresses and to prevent grain growth, warping, distortions during sintering. <br>The new techniques of dry nanopowder compacting were developed. The first technique is based on the powerful ultrasonic vibration (PUV) application to a special die (acoustic waveguide filled by nanopowder) simultaneously with uniaxial compaction pressure in quasi-resonance conditions when the PUV amplitude is proportional or equal to multiples of the particle or agglomerate mean size. Application of PUV during nanopowder compacting reduces the pressure gradients, hinder grain growth and preserve nanostructure during sintering. <br>The collector technique involves specially designed molds, where active and passive shaping surfaces are combined in one shaping member of the mold according to the principle of minimizing die-wall friction forces and specific rules of collective motion of the shaping members. These techniques were used for shaping (Ba,W)TiO3 nanopowder in manufacturing nanoceramic cases for microwave duplexers which nad dimensional tolerance of ±5 microns after sintering.