A new formula to calculate Adhesion energy
W of DLC films was suggested on the base of Bull's model using Critical load
Lc by scratch test in consideration of compressive residual stress
σres in the film. Beside, a new Adhesion parameter
J indicating Adhesion energy of the film was derived using fractured area ratio
Rb by 180° bend test. Further, with DLC films practically deposited on SUS304 under the various deposition conditions by UBM sputtering,
Lc by scratch test,
σres by substrate curvature measuring test, Young's modulus
EF by nano-indentation test, and
Rb by 180° bend test were obtained. Validity of these formula and parameter for Adhesion energy were assessed by evaluating changes in
Lc,
σres,
EF,
Rb,
W, and
J with deposition conditions of the DLC films. Critical load
Lc by scratch test changed significantly depending on the changes in mechanical property of
EF, and
Rb by 180° bend test changed with film thickness, were considered to be unreasonable as evaluating of film adhesion. While Adhesion energy
W and Adhesion parameter
J calculated by the formula suggested in this paper had a proportional relationship regardless of the deposition conditions. Both
W and
J were concluded to be derived appropriately for the evaluation of DLC film adhesion.
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