Effect of Al4B2O9 and Al18B4O33 whiskers synthesized in situ on the evolution of microstructure and mechanical properties of white fused alumina and Cubitron glass-ceramic composites

The present paper reports on the influence of in situ crystallization of aluminum borate whiskers on the evolution of the microstructure and mechanical properties of electrocorundum (white fused alumina) and microcrystalline alumina (Cubitron 321™) glass-ceramic porous composites. The investigated composites were obtained by sintering the white fused alumina (WFA) and Cubitron 321™ abrasive grains, glass-ceramic bond and various amounts of precursor for whisker growth. The results showed that in the presented technology, the crystallization of the composite reinforcing phases proceeds differently in both types of composites, which affects their microstructure and mechanical properties. An increase in the mechanical tensile strength of 36% was observed for both types of composites; however, depending on the type of abrasive grain, the composites with the highest tensile strength differed in the amount of whisker precursor added. A significant increase in the Young's modulus values was also observed for composites containing 40 wt% precursor: by 45% for WFA and by 52% for Cubitron 321™.