Mechanical and Tribological Properties of Fe-Based Powder Metallurgy Materials with Multi-Layer Porosity

The iron-based bearing materials with dense matrix and porous surface layer were made by powder metallurgy process. The microstructure and morphology were analyzed by scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction. The friction and wear properties of the composites were evaluated by an HDM-20 end-face friction tester. Results show that addtion of appropriate TiH₂ effectively improved the porosity of the iron-based powder metallurgy materials. And TiC phase, endogenous near the pore, can effectively compensate the weakening due to the pores. The addition TiH₂ increased the hardness but decreased the crushing strength. The fracture mechanism gradually changed from ductile fracture to brittle fracture. With the increase of TiH₂ content, the tribological properties became better first and then worsen. The comprehensive mechanical and tribological properties of the materials containing 3% TiH₂ were better, and the combination of high strength and good self-lubricating properties can be realized. This work provides a new idea for the development of high-performance iron-based oil bearing materials.