| Popis: |
objective of this investigation was to improve the tribological properties, particularly the solid particle erosion resistance, of slip cast alumina with the addition of small amount of zirconia nanoparticles. Two groups of suspensions, with solid loading of 70 wt.%, were prepared: the first one contained 100% of Al2O3 powder, while the second one contained 99 wt.% of Al2O3 and 1 wt.% of ZrO2 powder. Suspensions were homogenized in a planetary ball mill and green bodies were formed in prepared plaster moulds. The optimal amount of used commercial dispersant and homogenization parameters were determined and previously reported.1 As a result of two different suspensions, two types of green bodies and, subsequently, sintered samples were produced: monolithic Al2O3 and composite Al2O3-ZrO2 ceramics. Sintered samples were subjected to the solid particle erosion in order to discover whether the addition of zirconia nanoparticles improves the erosion resistance of alumina. Solid particle erosion can be defined as a degradation of material caused by repeated impacts of small solid particles.2 Silicon carbide was used as an erodent under different impact angles (30° and 90°). According to literature, the lower impact angle (30°) corresponds with abrasive erosion, while the higher one (90°) correlates to impact erosion.2 Wear mechanisms were analysed by comparing the surface roughness parameters (Ra, Rz, Rmax) before and after erosion. It is assumed that higher surface roughness after the test indicates lower erosion resistance.3 After the erosion test, all surface roughness parameters increased for both samples. Obtained results confirmed that this type of slip cast ceramics is more sensitive to impact than to abrasive erosion, because all surface roughness parameters were higher for the higher impact angle (90°), for both samples. This investigation also confirmed the hypothesis that tribological properties of alumina can be improved with the addition of the small amount of zirconia nanoparticles: all surface roughness parameters were higher for monolithic alumina than for composite alumina-zirconia, for both impact angles. |
