Am. Cock et al., COMPARISON OF 2 MODELS OF THIN DIAMOND FILM MICROHARDNESS DATA TO PREDICT THE HARDNESS OF CVD DIAMOND, DIAMOND AND RELATED MATERIALS, 3(4-6), 1994, pp. 783-786
Microhardness Knoop indentation testing of diamond films (1-3 mum thic
k) on silicon and on a titanium alloy is reported. The measured hardne
ss results were influenced by the substrate, and the results were mode
lled to give the hardness of the diamond film. Two models were used. T
he first was an empirical equation determined from finite element simu
lations of the load-displacement response of a hard film on a soft sub
strate. The second assumed the measured hardness to be dependent on th
e volume of the film and the volume of the substrate deformed. The fir
st model gave a better fit in both cases, predicting a diamond film ha
rdness of 112 GPa and 59 GPa for the silicon and titanium alloy substr
ates respectively. There is a large titanium carbide interfacial layer
between the diamond film and the titanium alloy substrate, which is p
robably the major reason for the lower predicted hardness result.