Effect of Stirring Speed on Mechanical Properties of the Inorganic-Powder- Reinforced Epoxy Composite

Abstract Inorganic powders (IPs), including SiO2, Al2O3, and Ca3Si3O9, were used as reinforcements and thermosetting epoxy resin was utilized as a matrix to manufacture IP/epoxy preform. The effects of stirring speed on the physical and mechanical properties of IP/epoxy composites were analyzed. Results showed that the tensile, flexural, and impact mechanical properties of IP/epoxy composites generally increased first and then decreased with the rise in stirring speed. They improved by 27.03%, 13.75%, and 8.78% when the stirring speed was 1000 r·min−1. When the stirring speed was less than 1000 r·min−1, the IP was unevenly distributed and prone to agglomeration and had weak junctions, which resulted in poor mechanical properties. When the stirring speed exceeded 1000 r·min−1, the particles with larger sizes were centrifuged, the powder was dispersed unevenly again, and the strength decreased.