The Influence of Selected Properties of Sintered Iron Doped with Lubricants on Its Tribological Properties

This study investigated materials intended for use in porous bearings, incorporating selected layered materials. Previous research has demonstrated that layered compounds, such as molybdenum disulfide (MoS₂), tungsten disulfide (WS₂), and hexagonal boron nitride (h-BN), can significantly enhance tribological performance. However, these improvements in tribological properties may be accompanied by undesirable characteristics that could limit the practical application of such materials. Therefore, further investigation was necessary to gain a better understanding of their behavior. To this end, composite materials containing iron (Fe) and varying amounts (0.5, 2.5, and 5 wt%) of layered materials were fabricated using powder metallurgy and sintering techniques. The study evaluated the impact of compaction pressure applied before sintering on the tribological properties and hardness of the materials. Additionally, the long-term stability of the composites was assessed after six years of storage under ambient conditions. The results confirmed that incorporating layered materials into the structure of porous bearing materials improves operating conditions and reduces the coefficient of friction by more than 20%. However, after six years of ambient storage, only the samples containing h-BN remained unchanged. Samples containing WS₂ or MoS₂ exhibited partial degradation, with evident signs of corrosion and grain fragmentation.