Preparation of YAG gel coated ZrB2–SiC composite prepared by gelcasting and pressureless sintering

In this paper, gelcasting and pressureless sintering of YAG gel coated ZrB 2 –SiC (YZS) composite were conducted. YAG gel coated ZrB 2 –SiC (YZS) suspension was firstly prepared through sol–gel route. Poly (acrylic acid) was used as dispersant . YZS suspension had the lowest viscosity when using 0.6   wt.% PAA as dispersant. Gelcasting was conducted based on AM–MBAM system. The gelcast YZS sample was then pressureless sintered to about 97% density. During sintering, YAG promoted the densification process from solid state sintering to liquid phase sintering . The average grain sizes of ZrB 2 and SiC in the YZS composite were 3.8 and 1.3   μm, respectively. The flexural strength , fracture toughness and microhardness were 375   ±   37   MPa, 4.13   ±   0.45   MPa   m 1/2 and 14.1   ±   0.5   GPa, respectively.