Experimental investigation on the durability and failure modes of polybutylene terephthalate/calcium carbonate nanocomposite gears

Abstract There is a lack of sufficient research in the gear performance and failure of polymer nanocomposites. Within this contribution, hence, the endurance and failure of polybutylene terephthalate (PBT)/calcium carbonate (CaCO3) nanocomposite gears were explored under constant-loading regime. A gear test rig was designed and fabricated in-house to conduct the gear tests and a digital camera was used for post-processing image analysis of wear and failure characteristics. The tooth surface strain was calculated via digital image correlation (DIC) technique. According to the results, the gear lifetime was increased by 84% and 63% at the loadings of 6 and 11 Nm, respectively, with CaCO3 additions. The inclusions of CaCO3 systematically lowered bulk temperature and tooth wear. The damage type was altered from pure thermal bending for the plain PBT gear to pitch cracking for the nanocomposite gears at 11 Nm. The wear microstructure of PBT and nanocomposite gears showed prominent adhesion and abrasion signs, respectively. Furthermore, the DIC results indicated a lower plastic deformation on the teeth of nanocomposite gears.