Wear properties under dry sliding of Lu-α sialons with in situ reinforced microstructures

In situ reinforced microstructures in Lu-α sialons have been developed by sintering compositions which resulted in the presence of an extended liquid phase, and which forms a secondary crystalline grain boundary phase on cooling. The wear properties of these materials have been assessed under dry sliding conditions through block on ring wear tests under different loads, and compared with the wear properties of an equiaxed Lu-α sialon, which had good wear resistance under low loads but a high wear rate under higher loads. The presence of the elongated grain microstructure resulted in improvements in mechanical properties and a reduction in the high load specific wear rate of about 1 order of magnitude. Under low load wear tests, samples sintered with Lu2SiO5 as the additional liquid former resulted in an increase in wear rate due to extensive removal of the silicate grain boundary phase. However, samples in which the liquid formation was achieved through additions of Lu2O3 only, in addition to reducing the high load wear rate, maintained the good low load wear resistance seen for the equiaxed material.