Fabrication of Oriented SiC‐Whisker‐Reinforced Mullite Matrix Composites by Tape Casting

Dense SiC‐whisker‐reinforced mullite composites with up to 50 vol% whiskers can be obtained by tape casting and hot pressing. The tape casting process results in high degrees of SiC whisker orientation as determined visually and by X‐ray diffraction. The ability to achieve dense composites with as much as 50 vol % whiskers is attributed to the higher percolation threshold of aligned whiskers. The factors affecting the degree of whisker orientation during tape casting are described using a fluid dynamics model derived from Jeffery's equations and show that the orientation of anisometric particles is enhanced primarily by the casting rate and particle aspect ratio.