Solutions of rare earth modifier (RES) and epoxy chloropropane (ECP) grafting modification method were used for the surface treatment of aramid fiber. Tensile properties of both the aramid/epoxy composites and single fibers were tested. The effects of RES concentration on tensile properties of aramid/epoxy composites were investigated in detail to explore an optimum amount of rare earth elements in solution for modifying aramid fiber. The fracture surface morphologies of tensile specimens were observed and analyzed with the aid of SEM. The experimental results show that rare earth treatment is superior to ECP grafting treatment in promoting interfacial adhesion between the aramid fiber and epoxy matrix. Meanwhile, the tensile strengths of single fibers were almost not affected by RES treatment. The optimum performance is obtained when the content of rare earth elements is 0.5 wt %.

An investigation of the effect of rare earth elements (RE) on erosion resistance of nitrided 40Cr steel is carried out using an erosion test rig in a water-based slurry with quartz particles. Results indicate that a significant improvement occurs in erosion resistance of nitrided 40Cr steel by introducing RE in nitriding processes comparing conventional nitriding processes. Measurement of physical properties exhibits that both hardness and toughness of nitrided 40Cr steel increase in the case using RE-nitriding processes comparing the conventional. Metallurgical microscopy reveals that there is a transformation from a coarse to a fine metallurgical microstructure in the case and an increase in the thickness of white layer on the top of case attributed to an introduction of RE in nitriding, which attributed to an improvement in erosion resistance and physical properties. EDX analysis shows that RE diffuse into the case of 40Cr steel in nitriding process as a result of appearance of micro-alloy. Microscopy revealed that the furrow-like peeling from plastic deformation of material is predominant erosion mechanism of RE nitrided 40Cr steel while the furrow-like peeling with initial cross crack and large grinding peelings takes place predominantly in tests of conventionally-nitrided ones, which results in a significant difference in erosion resistance.

Polytetrafluoroethylene (PTFE) composites were prepared using 60 wt.% Pb and 5 wt.% glass fiber (GF). The surface of GF was modified with a coupling agent, a mixture of coupling agent and rare earths, and rare earths, respectively. The friction and wear properties of the PTFE composites, sliding against 45# carbon steel (AISI 1045 steel) under oil lubrication, were investigated on a pin-on-disc sliding wear machine. It was found that modified GF, which was filled into PTFE, decreased the wear of the PTFE composites compared with that of the PTFE composite filled with unmodified GF. The friction and wear properties of PTFE composite filled with Pb and rare earths-modified GF were greatly enhanced, owing to the effective improvement of the interfacial adhesion between the GF and PTFE.

The friction and wear properties of metal-plastic multilayer composites filled with glass fiber, which is treated with rare earth element surface modifier, under impact load and dry friction conditions were investigated. Experimental results show that the metal-plastic multilayer composite filled with glass fiber exhibits excellent friction and impact wear properties when using rare earth elements as surface modifier for the surface treatment of glass fiber.