Xuehu Men

Phenolic resin (PF) and molybdic acid–modified phenolic (Mo-PF) have been synthesized and developed and combined with polyfluo wax (PFW) to fabricate PF-PFW and Mo-PF-PFW composite coatings. The effects of applied load and sliding speed on the tribological properties of the phenolic composite coating were evaluated using a block-on-ring wear tester. Compared to the PF composite coating, the Mo-PF displayed a lower friction coefficient and a higher wear life under all tested conditions. Scanning electron microscope (SEM) investigation showed that the Mo-PF composite coating had a smooth worn surface after the friction test, and a continuous and uniform transfer film was formed on the surface of the counterpart ring. The improved tribological properties of Mo-PF composite coating resulted from its enhanced thermal properties.

The development of a phenol formaldehyde/graphene (PF-graphene) composite coating with high performance is desirable but remains a challenge, because of the ultrahigh surface area and surface inertia of the graphene. Herein, we synthesized PF-graphene composites by thein situpolymerization of phenol and formaldehyde with the addition of graphene oxide, resulting in improved compatibility between the graphene and phenolic resin (PF) matrix and endowing the phenolic resin with good thermal stability and excellent tribological properties. Fourier-transform infrared (FTIR) spectra and X-ray diffraction (XRD) patterns demonstrated that the graphene oxide was reduced during thein-situpolymerization. The PF-graphene composites were sprayed onto steel blocks to form composite coatings. The effects of an applied load and of the sliding speed on the tribological properties of the PF-graphene composite coating were evaluated using a block-on-ring wear tester; in addition, the worn surface and the transfer film formed on the surface of the counterpart ring were studied by scanning electron microscopy (SEM). The results show that the PF-graphene composite coating exhibited enhanced tribological properties under all tested conditions.

A Nomex fabric/phenolic composite was prepared, and its tribological properties were evaluated under dry and water-bathed sliding conditions by a pin-on-disk tribometer. The resulting size of the friction coefficient for the Nomex fabric/phenolic composite in the study occurred in the following order: dry sliding condition > distilled water-bathed sliding condition > sea water-bathed sliding condition. The fabric composite’s wear rate from high to low was as follows: distilled water-bathed sliding condition > sea water-bathed sliding condition > dry sliding condition. Under water-bathed sliding conditions, penetration of water into the cracks accelerated the composite’s invalidation process, resulting in a higher wear rate. We also found that the extent of corrosion and transfer film formed on the counterpart pin significantly influenced the wear rate of the Nomex fabric composite. Discussion of the Nomex fabric composite’s wear mechanisms under the sliding conditions investigated is provided on the basis of the characterization results.