| Powder metallurgical friction materials have been widely used in high speeds and heavy loads situations such as heavy-duty locomotive, train and airplane as well as engineering machines, mainly including the Fe-based, Cu-based and Fe-Cu-based friction materials systems. However, there are some defects in friction and wear properties and application due to the characteristics of its composition. For instance, the Cu-based friction materials are characterized by good thermal conductivity, stable friction coefficient and low wear rate, but high cost and poor high temperature properties. The Fe-based friction materials are characterized by high friction coefficient, good thermal resistance and low cost, but incline to adhere to the couple, poor oxidation resistance and rust resistance as well as worse wear resistance than Cu-based friction materials. Ceramics and composites are characterized by low density, high strength and high wear resistance and chemical stability as well as stable friction coefficient at high temperature, but the brittleness and difficulties in processing hinder the further application in friction materials. It is important and urge to develop new kinds of friction materials with excellent properties.Fe3Al intermetallics, with super-lattice structure, possess metallic bond, covalent bond and ion bond in binding mode. The unique structure determines the special mechanical properties. The oxidation and corrosion resistance, the high temperature creep property, and the high temperature strength are higher than most metallic materials, and the higher thermal conductivity and plasticity than ceramics. As a new kind of cheap material with low density whose properties are between alloys and ceramics, they are regarded as semi-metallic and semi-ceramic materials. Meanwhile, Fe3Al intermetallics have favorable wear resistance, implying that its potentials in the field of friction materials. In this paper, the wear resistance of hot pressing sintered Fe3Al intermetallics was investigated in detail. Based on this, corresponding Fe3Al-based composite friction materials weredesigned and fabricated, the processing, microstructure, mechanical properties and tribological properties and mechanisms of which were studied systematically. The main contents are as follows:1. Fe3Al powders were prepared by mechanical alloying with annealing treatment. Fe3Al bulk materials with 97% relative density and grain size of 600~800nm were obtained by hot-pressed sintering in vacuum. It is mainly characterized by the low ordered B2 structure, together with some dispersed Al2O3 particles and α-Fe (Al) solid solution. The mechanical properties of Fe3Al bulk materials were significantly improved comparing with casting ones, with the bending strength of 1000~1400MPa, compressive yielding strength and compressive strain of 1200~1800MPa and 10%~15%, and HRC 55-60.2. The wear resistance and mechanisms of hot pressing sintered Fe3Al intermetallics with different Al content and alloying elements are studied systematically. It was found that the wear resistance increased with increasing Al content, with the lowest volume loss of Fe-32A1 and irregular value of Fe-30Al. The addition of alloying elements improved the wear properties to different degrees, especially the Ti. The Fe-28Al-10Ti possesses excellent wear resistance, the volume loss of which is only 1/100 of the Fe-28A1. The excellent wear resistance of Fe3Al should be attributed to its unique structure: ordered reinforcing, high processing hardening rate, grain refinement, the precipitation of secondary phases and oxides, solid solution reinforcing of alloys and structure uniformity. SEM morphology of wear surface and corresponding EDS indicated that there were obvious differences in wear mechanisms of sintered Fe3Al under different testing conditions. Under lower loads plastic deformation occurred on the wear surface and the wear performance is mainly particle abrasion, the characteristics of which are mi...
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