Tailoring dielectric properties of cordierite-mullite ceramics through Ceramic Injection Moulding

Cordierite-mullite ceramics have been processed by Ceramic Injection Moulding (CIM) for the first time. The comparison with cordierite-mullite ceramics obtained by conventional ceramic process (CP) proves the effect of processing on the structure, microstructure, thermal and dielectric properties. CIM processing favours formation of larger content of mullite phase, a more homogeneous microstructure and reduced porosity than by conventional processed ceramics. These factors strongly condition the dielectric behaviour, which is analyzed by complex impedance formalism up to 850 °C and 1 MHz. The conduction mechanism is thermally activated and the activation energy is ~2.5 times larger in CP than in CIM ceramics. Thermal expansion coefficient is tuned by processing method, ranging from 3.9·10−6 °C−1 to 4.6·10−6 °C−1. All these findings show the strong influence of processing in cordierite-mullite ceramic composites. This work shows that tailoring composition and CIM parameters allow cordierite-mullite composites to precisely fulfill the requirements for future electronic applications.