The influence of thermo-cycling and cyclical loading on metal/resin interfaces.

摘要

This study investigated the behaviour of metal/resin laminates of dimethacrylate resins and cobalt chromium alloy (Co/Cr) when subjected to fatigue stressing by thermo-cycling and cyclical loading, after water storage. The veneering materials used were a microfine (Silux Plus) and a hybrid (Z100) composite, bonded to a Co/Cr alloy through an adhesive interface (Cesead opaque primer and body opaque resin). Characterisation of the two composite resins was carried out with particular attention to water sorption. Laminates were evaluated over a period up to six months, groups of ten specimens were load cycled alone (Ld) (up to 453,600 cycles at 5 Hz), thermo-cycled alone (Th) (up to 25,200 cycles between 4°C, 37°C and 60°C) load cycled and thermo-cycled (Ld/Th) (cycled as above). Following testing, laminates were assessed for their elastic modulus, examined microscopically and the adhesive interface was subjected to a dye penetration study. The microfine resin absorbed more water than the hybrid (2.88% and 1.84% by mass respectively) and lost more soluble material (0.61%, 0.19% of original mass respectively). The laminates of the different veneering resins exhibited differences in their elastic behaviour. The apparent flexural modulus of laminates made with the hybrid resin (initial: 482.3 +/- 69.1 GPa, week 24 Ld/Th; 544.7 +/- 70.3 GPa) was higher than those made with the microfine resin (initial: 288.1 +/- 44.4 GPa, week 24 Ld/Th; 353.7 +/- 47.5 GPa). The extension at failure of the hybrid resin laminates appeared to be lower than that of the microfine ones. However, little difference was seen in the stress at failure between groups. Week 24 Ld/Th; (Z100: 833.3 +/- 355.8 MPa, Silux Plus: 828.4 +/- 122.1 MPa). Both cohesive failure within the veneering resin and adhesive failures between the veneering resin and metal component were noted.