Sintering of Al2O3-TiB2 nano-composite derived from milling assisted sol-gel method

Synthesis and sintering of an alumina /titanium diboride nano-composite have been studied as an alternative for pure titanium diboride for ceramic armor applications. Addition of TiB2 particles to an Al2O3 matrix can improve its fracture toughness, hardness and flexural strength and offer advantages with respect to wear and fracture behavior. This contribution, for the first time, reports the sintering, microstructure, and properties of Al2O3-TiB2 nano-composite densified with no sintering aids. Nano-composite powder was produced by combination of sol-gel and mechano-chemical methods. The densification experiments were carried out using both hot pressing and pressureless sintering routes. In the pressureless sintering route, a maximum of 92.3% of the theoretical density was achieved after sintering at 1850°C for 2 h under vacuum. However, hot pressing at 1500°C for 2 h under the same condition led to achieving a 99% of the theoretical density. The hot pressed Al2O3-TiB2 nano-composites exhibit high Vickers hardness (16.1 GPa) and a modest indentation toughness (~4.2 MPa.m1/2).

nano-composite; sol-gel; pressureless sintering; hot-press; Al2O3-TiB2.