Abstract
Composite tetragonal zirconia (3Y-TZP) sinters with Al2O3 contents of 0, 1, 5, 10 and 15 mol% were obtained from a 3-YSZ powder prepared using the gelatin method, and the influence of alumina addition on the mechanical and electrical properties of the obtained sinters was investigated. Al2O3 was added via two different methods, namely during the preparation of the 3-YSZ powder and via impregnation using an alcohol solution of aluminum nitrate. The obtained green bodies were sintered for 2 h in air at 1773 K. The structure and morphology of the two series of sinters were investigated using XRD and SEM-EDS, their electrical properties were determined using impedance spectroscopy, and their hardness and critical stress intensity factor were measured using the Vickers indentation test. We established that both the amount of alumina and the method used to introduce it into the 3Y-TZP matrix significantly affect the physicochemical properties of the obtained polycrystalline material. The 3-YSZ/10 mol% Al2O3 sinter that had Al2O3 introduced during the preparation of the 3-YSZ powder was found to exhibit the most advantageous mechanical and electrical properties while still having sufficiently low porosity.
Highlights
A solid oxide fuel cell (SOFC) is an electrochemical device that generates electrical energy via the simultaneous oxidation of fuel and reduction of oxygen, both of which are supplied from an external source [1]
Zirconia (3-YSZ) powder stabilized with 3 mol% of yttria with nano-sized crystallites containing both tetragonal and monoclinic phases was obtained via the gelatin method and calcinated
This powder was shown to be suitable for the preparation of dense 3Y-TZP/Al2O3 composite sinters with different amounts of Al2O3 (1, 5, 10 and 15 mol%) added either during the preparation of the 3-YSZ powder or via impregnation using an alcohol solution of aluminum nitrate
Summary
A solid oxide fuel cell (SOFC) is an electrochemical device that generates electrical energy via the simultaneous oxidation of fuel and reduction of oxygen, both of which are supplied from an external source [1]. Namely batteries [2], solid oxide fuels do not need to have energy stored in them before generating current, and their operating time is not reduced in the same manner. Since the operating conditions of SOFCs are rather harsh and involve high temperatures and an oxidizingreducing medium in the work space of both the cathode and the anode, the applied electrolyte materials must meet a number of strict technical and technological requirements. Most importantly, they need to exhibit high ionic conductivity (in excess of 10−2 S·cm−1) with no electronic conductivity component. They must have considerable thermochemical stability and low porosity and, gas-tightness and high mechanical strength [1,5,6]
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