Pixelated Ultra-Fast Sintering Technique – PixUFaST

A study was conducted to compare the fast pixelated sintering and the SPS (spark plasma sintering), with temperature ramps up to 100°C/min, of two model ceramic materials (a-alumina and 3%mol yttria stabilized zirconia). For this purpose, a preliminary slipcasting shaping study of the ceramics was performed. The repeatable and reproducible experimental protocol resulted in compacts with a relative density of 60% and granular stacks of controlled quality. The investigation strategy was then turned towards a sintering analysis based on an analytical modeling from dilatometric tests and on the establishment of sintering maps.

Academic results:
- Validation of pixelated sintering as a conventional technique, without any specific mechanisms and with rapid sintering capabilities similar to SPS,
- Application to the consolidation of large parts with generation of gradients in the volume (porosity, microstructure),
- Demonstration of multi-step sintering capabilities.
Industrial results:
- Design/realization of a demonstrator adapted to the sintering of large parts (> 10 cm2),
- Growth of Galtenco Solutions, industrial partner, whose staff at the beginning of the project was 2, whereas it is now 7 (plus 1 CIFRE PhD thesis and 1 apprentice engineer).

The academic work is continuing in the framework of a CIFRE PhD thesis (Galtenco Solutions / ICMCB). The aim is to explore the capabilities of pixelated sintering for temperature profile control. It is also envisaged to exploit the digital chain to drive the sintering in real time using a feedback loop by interfacing sensors (e.g. size of the sample). From an industrial point of view, the project has allowed Galtenco Solutions to increase its workforce by a factor of 4, with new markets opening up (e.g. reactors-exchangers) and a project to build a production unit.

Because of the industrial stakes linked to the development of Galtenco Solutions on the basis of this key technology, the dissemination during the project has been voluntarily limited and staggered in time (2 publications are being written to date: one on the pixelated sintering of alumina and the other on the pixelated sintering of zirconia).

PixUFaST aims at developing an original sintering technology using a "mold" made of resistive heating elements, that mold being used as a modular "furnace". The heating elements are arranged around the part to be sintered based on prior multiphysics modeling. The basic unit comprises a power supply, a resistive heating element and a thermocouple located as close as possible to the sample. This unit can be repeated "infinitely" (i.e. discretization of the heating system, pixelated furnace). This is a major technological breakthrough. The entire sintering cycle is controlled by a proprietary software that drives each heating element independently, using a thermocouple which is paired to it. The energy delivered to the part is optimized and thermal losses are limited. Beyond energy intensification, sintering is free which opens prospects for the consolidation of complex 3D parts and for transfer to large scales.