A comparison between Knoop and Vickers hardness of silicon nitride ceramics

摘要

The hardness values of seven silicon nitride ceramics were measured at an applied load of 2.45 N for both Vickers and Knoop indenter geometries. It was found that the measured Knoop hardness, H_K, is generally lower than the corresponding Vickers hardness, H_V. There is a strong correlation between (H_V/H_K) and (a/d), where a and d are the measured lengths of the minor and the major diagonals of the Knoop indentation, respectively. Such a correlation indicates that the difference between H_V and H_K may be attributed to the elastic recovery occurring at the indentation.