Effect of various impurities on the hardness of NaCl crystals

The hardness of NaCl crystal in the presence of mono, divalent and polyvale nt ions were measured. Measurements were made in the indentation load range from 5x10(-3) to 20x10(-3) N. The measured data showed that there is an in dentation size effect. Classical Meyer's law was used for the characterizat ion of, crystal hardness of NaCl. The Meyer index was found to be smaller t han 2 indicating brittle material characteristic. The PRS model was also us ed for the determination of the load-independent microhardness value. It wa s found that the crystal hardness of NaCl is chancing depending on the type of impurity and the concentration.