Microhardness analysis
The Knoop microhardness was measured using a microhardness tester (Micro Hardness
Tester HMV-2, Shimadzu, Tokyo, Japan) with a pyramid-shaped diamond indenter set
to a vertical static load of 25 g for 5 seconds. The largest diagonal of the
indention was measured. Three initial readouts were taken for each fragment at
defined locations, as described for the surface roughness, and the mean was
considered the initial microhardness value. After the treatments, final
microhardness readouts were performed. The microhardness alteration was
determined by the difference between the final and initial measurements (ΔKHN =
KHNf - KHNi) 