Permeability and Load Capacity of Iron Porous Bearings with the Addition of Hexagonal Boron Nitride.

Due to their properties, porous sliding bearings are considered to be maintenance-free, which means that no lubrication is required during operation. Their design enables operation at low rotational speeds with high load. Another effect of this bearing design is the lubrication continuity in the tribological pair. In this study, the selected tribological properties (such as load capacity and permeability) of new-generation iron porous bearings with boron nitride powder were experimentally investigated. Tests were carried out under various conditions, using unique test apparatus. The addition of 3% (weight) of hexagonal boron nitride (hBN) significantly increased the load capacity of tested porous bearings in comparison to the same standard bearings containing 2.5% copper. The obtained p·v rating reached almost 7 MPa, which is a value almost three times higher than the requirements for this type of bearing. It is worth emphasizing that such a result was obtained despite a noticeable deterioration in the air and oil permeability of the bearing.