The Spanish National Research Council (CSIC), in collaboration with the University of Seville, has developed a whole new procedure for advanced materials sintering which, based on the electric current isolation within the mold where the sample is, allows the electric current to concentrate exclusively on the material to be sintered. Therefore, the sintering of any material can be completed in less than a minute and with an energy efficiency up to 100 times higher than it would be by using ordinary molds.
Description
A key aspect for the technical-economic development of advanced materials production to an industrial scale is the energy consumption required to reach the high temperatures needed for the process of their fabrication (600-2700ºC), being thus extremely important to be able to produce these materials at the lowest energetic cost.
Currently, the most efficient techniques in advanced materials sintering consist of the use of electric currents, at a low voltage for a short and a certain time interval. This method, named SPS (Spark Plasma Sintering) has, however, a drawback, since the applied electric current flows through the mold where the sample of material is placed, making thus the energetic performance being not what it was expected.
Having energy efficiency as a main goal, a mold electrically insulated inside has been designed so that the electric current can be concentrated. And what is more, this mold makes it possible to sinter any advanced material in less than a minute.
The design entails the use of a thin layer of AI2O3 fibers that enables the electric insulation of the mold. Another thin layer of graphite is used to avoid any reactions between the material to be produced and the insulating layer. In this way, the designed mold allows the production of advanced materials with an energy efficiency up to 100 times higher, in less than a minute, compared to the use of ordinary molds. Its competitiveness is thus increased and now its implementation on an industrial scale is possible.
Main uses and advantages
• Greater energy efficiency, up to 100 times higher than by using SPS.
• The intensity of the electrical current needed to produce a material is noticeably lower (between 30 to 200%) than by using SPS.
• Maximum temperatures about 2700ºC, with heating rates over 3000ºC/minute.
• Controlled electric field which can now be more intense than it used to be by using SPS.
• Versatile. Now it is possible to work with different modes of electrical concentration and electrical field according to the mold settings and the electric origin of the material to be produced.
• Low cost design and fabrication of larger samples.
• Useful for the production of any given advanced material, monoliths or composites. For instance, Al2O3, Al2O3/C composites, YTZP, ZrB2, MoSi2…