An agarose-epoxy resin composite system for enhancing green body strength in microwave dielectric ceramic filters

Abstract

As an environmentally friendly and pollution-free natural biological macromolecule, agarose has the characteristics of dissolving in water at high temperatures and solidifying into a gel upon cooling. Hence, it is suitable for gel casting. This study constructed an agarose-epoxy resin composite gel system for the preparation of MgTiO₃–CaTiO₃ microwave dielectric ceramic filters. The slurry with a ceramic powder content of 80 wt% and 3 wt% agarose-epoxy resin composite gel solution was selected. Then, after mixing, heating and stirring, casting, and 15–20 hof drying, the green body was obtained. Three-point testing showed that the bending strength of the green body prepared from the composite system reached 11.32 MPa. This was 14.46% higher than that of the system employing just agarose, where the green body prepared with agarose alone had a bending strength of 9.89 MPa. This result showed that adding an appropriate amount of epoxy resin could enhance the strength of the green body. After the green body was debinded and sintered, the ceramic samples produced from the composite system had a bending strength of 95 MPa. This was similar to the value of 92 MPa for the system with just agarose. This confirmed that the addition of epoxy resin was able to enhance the strength of the green body, allowing it to adapt to mechanical processing without damaging the performance after sintering. Based on this, the composite system was successfully used to prepare second-order waveguide filters, demonstrating its ability to form complex structures. This proved that the composite agarose system was suitable for the preparation of microwave dielectric ceramic filters. This composite system had the advantages of being environmentally friendly and having a short gelation time, providing a new solution for ceramic filter preparation.