Preparation and Tribological Properties of Starch/Copper‐Based Oil‐Containing Materials Using Green Biodegradable Biomass

ABSTRACT

Regulating pore structure by using pore‐forming agents (PFAs) is an effective strategy for improving the self‐lubricating performance of oil‐containing materials. However, the application of conventional PFAs has been limited by their low decomposition temperatures and the release of toxic gases during decomposition. In this study, starch, a green and biodegradable biomass material, was employed as a PFA to prepare copper‐based oil‐containing materials with varying starch contents by powder metallurgy. Oil storage and release tests, sliding friction experiments, and mechanical property measurements were conducted to investigate the effect of starch on pore structure and tribological behaviour. The results show that increasing the starch content changes the pore morphology from isolated closed pores to interconnected network pores, thereby improving oil storage and release. However, with increasing starch addition, the friction coefficient and wear rate first decrease and then increase, whereas the mechanical properties gradually decline because of the development of the porous network. At 5% starch, the hardness, density, crushing strength, and impact toughness decreased by 20.0%, 19.9%, 22.4%, and 22.8%, respectively, compared with those of the starch‐free material. At 3% starch, the moderately interconnected pores provide both effective oil release and sufficient matrix strength, resulting in the lowest friction coefficient and wear rate, which were reduced by 84.8% and 84.3%, respectively, relative to the starch‐free sample. These findings clarify the mechanism by which starch regulates pore structure and tribological performance in copper‐based materials and provide guidance for the use of biodegradable PFAs in the design of environmentally friendly self‐lubricating materials.