Small is the new Big thing. In the case of bulk polycrystalline materials, this size revolution means aiming for a small grain size in sintered materials. Achieving a microstructure with a grain size in the order of nanometres makes it possible to improve a number of material properties in structural and functional materials such as materials for machining, transparent ceramics, magnetic materials, etc.
In order to achieve high-density sinters and to prevent grain growth, the material consolidation process must be carried out quickly by heating it to a sufficiently high temperature in a short period of time and/or by aiding sintering acceleration processes. A very big improvement over traditional sintering methods has been made possible by the SPS method.
Another step forward is the RACS method, which is a further development of the SPS method. As in the SPS method, the energy for sintering is provided in the form of current pulses, but these are high-frequency alternating current pulses generated by a resonant power supply coupled to a matching transformer. This method enables efficient consolidation of materials by sintering, particularly ionic materials, due to the AC current not causing ion migration and component segregation. The advantage of the device is the high efficiency in the transfer of energy between the power supply and the sintered powder material sample. The high efficiency is achieved by matching the resonant circuit to the matrix with the consolidated powder and operating the system in resonance. In addition, the placement of the matching transformer in close proximity to the die, allows the use of short current leads, which effectively reduces the amount of Joule-Lenz heat dissipated in them and reduces losses.
This allows highly efficient consolidation of metallic, ceramic, semiconductor, nanocrystalline, submicron and micron powder materials, in the electrothermal sintering process.
