Microstructure and Mechanical Characterization of Novel Al(2)O(3)–(NiAl–Al(2)O(3)) Composites Fabricated via Pulse Plasma Sintering

The scientific goal of this paper is to study and explain the relationship between the microstructure of a ceramic–intermetallic composite fabricated by consolidating a mixture of Al(2)O(3) and NiAl-Al(2)O(3) using the PPS technique and its basic mechanical properties. Six series of composites were manufactured. The obtained samples differed in the sintering temperature and content of compo-powder. The base powders, compo-powder, and composites were investigated using SEM equipped with an EDS and XRD. Hardness tests and K(IC) measurements were applied to estimate the mechanical properties of the fabricated composites. The wear resistance was evaluated using a “ball-on-disc” method. The results demonstrate that the density of the obtained composites increases with the increased temperature of the sintering. The content of NiAl + 20 wt.% Al(2)O(3) did not have a determining effect on the hardness of the manufactured composites. The highest hardness, contacting 20.9 ± 0.8 GPa, was found for the composite series sintered at 1300 °C and 2.5 vol.% of compo-powder. The highest K(IC) value from all the studied series equaled 8.13 ± 0.55 MPa·m(0.5) and was also achieved for the series manufactured at 1300 °C (2.5 vol.% of compo-powder). The average friction coefficient during the ball-friction test with the Si(3)N(4) ceramic counter-sample was between 0.8 and 0.95.