HARDENING AND EMBRITTLEMENT OF POLYIMIDES BY ION-IMPLANTATION

Nanoindentation tests performed with a sharp diamond pyramid of apical angle 35-degrees provided very quantitative depth hardness in polyimi des implanted with C, N, O, Ne or Si ions. In all cases the hardness i ncreased steeply when the amount of deposited energy reached a value o f the order of 20 eV/atom. For an amount of energy ten times higher th e polymer was transformed into an amorphous hydrocarbon and the harden ing factor saturated at a value of 13 to 20. But this carbonized layer was poorly adherent, as evidenced by reproducible discontinuities in the depth-versus-load curves, when the indentor tip reached the interf ace.