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For a present study, the surfaces of graphite/epoxy prepregs were modified using plasma treatment to improve the delamination resistance behavior of graphite/epoxy laminated composites. The optimal treatment time was determined by measuring the change of contact angle with treatment time. Unidirectional DCB (double cantilever beam) specimens were used in the mode I delamination fracture tests. The delamination resistance curve of regular (untreated) specimen was compared with that of plasma-treated specimen in order to determine the effect of prepreg treatment on the resistance behavior. It was found that contact angle was changed from ~64° to ~47° depending on the treatment time. The contact angle was a minimum for a 30 min treatment time. It was also found that delamination resistance behavior of graphite/epoxy composites was improved about 20%.

In this study, the tempering effect on the wear characteristics of induction-hardened SPS5 steel was investigated. For this purpose, three tempering conditions were applied to control the hardness and microstructure of heat-treated SPS5 steel. Ball-on-disk wear tests have been performed using zircornia balls on the tempered specimens to determine the variation of wear characteristics. The results showed that friction coefficient decreased with increasing hardness for induction-hardened SPS5 steel. This seems to occur because real contact area between specimen and mating ball was affected by the specimen hardness. Also, we observe the wear type changes from the plowing wear to the adhesive wear as the hardness increases and the adhesive wear particles act as an obstacle to the transmission of the force of friction, reducing the coefficient of friction and the wear rate.