摘要
A comparative study was carried out on the load-dependent indentation behavior with respect to hardness and induced cracks ofβ-SiAlON andα-silicon carbide ceramics.It is observed that silicon carbide(SiC)exhibits lower transition load,early cracking and severely crushed indentation sites,whereasβ-SiAlON shows higher transition load and damage-free indentation zone even at the maximum applied load(294.19 N).Crack density is higher forα-SiC with comparison toβ-SiAlON at each load.SiC exhibits both main and secondary radial types of cracking from low indentation load(0.98 N).Cracks are often associated with branching at higher load(>9.80 N)forα-SiC.β-SiAlON exhibits cracks which are mainly radial types initiated at 4.90 N load.These opposing behaviors ofβ-SiAlON andα-SiC are attributed to their difference in hardness,toughness,and brittleness index.Higher brittleness ofα-SiC results in early and severe cracking around its indentations.β-SiAlON shows less cracking due to its lower brittleness and higher toughness.The increased size of indentation-induced cracks ofα-SiC is higher than that ofβ-SiAlON due to the rapid crack propagation inα-SiC with transgranular fracture behavior.
