The friction and wear properties under impact load and dry friction conditions of metal2plastic multilayer composites filled with glass fiber, treated with rare earth elements, were investigated. The worn surfaces were observed and analyzed by scanning electron microscopy (SEM). It shows that applying rare earth elements surface modifier to treat the glass fiber surface can enhance the interfacial adhesion between the glass fiber and polytetrafluoroethylene (PTFE), as well as promote the interface properties of the composites. This helps to form a uniformly distributed and high adhesive transfer film on the counterface and abate the friction between the composite and the counterface. As a result, the wear of composite is greatly reduced. The composite exhibits excellent friction properties and impact wear2resistance.

Equal channel angular extrusion (ECAE) process was a deep pure shear deformation method for structural materials, developed in early 90s. ECAE technique has been successfully applied to several pure metals and alloys to refine the microstructure and improve the mechanical properties of materials. In the present paper, TiNi shape memory alloys have been treated by ECAE process. The effects of ECAE process on microstructures and transformation behaviors have been investigated. The initial coarse grains of TiNi alloy were refined after two passes of ECAE processes and short annealing at 1023 K. Transformation temperatures of TiNi alloy sharply decreased after two ECAE processes, then rapidly rose back when annealed at 773K for 2h.

Effects of heat treatment and high-temperature equal-channel angular extrusion (ECAE) process on transformation behaviors of Ti-50.3at.%Ni shape memory alloy (SMA) were investigated by differential scanning calorimeter (DSC) measurements. The martensitic transformation start temperature of TiNi alloy decreased sharply after high-temperature ECAE processes, then rapidly rose back after the specimen annealing at 773K for 2h. Reasons for the changes of phase transformation behaviors have been discussed.

Polytetrafluoroethylene (PTFE) composites were developed by filling with 60 wt.% Pb and 5 wt.% glass fiber (GF). The GF was modified with an alcoholic solution (SGS) of N-β-aminoethyl-β-aminopropyltrimethoxysilane coupling agent (SG-Si900), an alcoholic solution (SGS/RES) of SG-Si900 and rare earths, and an alcoholic solution (RES) of rare earths, respectively. The friction and wear properties of these PTFE composites, reciprocating sliding against chromium-plated steel in dry friction, under both static loads and impact loads, were investigated. The worn surfaces of the PTFE composites and the transfer films formed on the counterface were examined with a scanning electron microscope (SEM). Experimental results reveal that the wear resistance of PTFE composites filled with modified GF can be largely improved. The friction property of PTFE+60 wt.% Pb+5 wt.% RES modified GF composite is the best of the PTFE composites filled with modified GF. However, the wear resistance of PTFE composites is largely decreased under impact loads, compared to that under static load conditions. The PTFE + 60 wt.% Pb + 5 wt.% RES modified GF composite registers excellent impact wear resistance in dry reciprocating sliding under impact load conditions. SEM investigation reveals that the modified GF can enhance the adhesion of the transfer films to the counterface, so they largely decrease the wear of the PTFE composites. Under impact load conditions, the PTFE debris on the worn surfaces of the PTFE composites is characterized by fine powder, owing to the repetitive impact in dry reciprocating sliding, which can decrease the ability of PTFE to form its transfer films, and then leads to the decrease of the friction and wear properties of the PTFE composites.

Three types of surface modifiers, N-β-aminoethyl-y[1]-aminopropyltrimethoxysilane coupling agent (SGS), a mixture of silane and rare earth elements (SGS/RES), and rare earth elements surface modifier (RES), were used to treat the glass fiber surface. Tensile tests of glass fiber–reinforced polytetrafluoroethylene (GF/PTFE) composites with different surface treatment conditions, surface modifiers, and glass fiber content were carried out. Finally, the fracture surface morphologies of GF/PTFE composites were investigated using scanning electron microscopy. Experimental results showthat the tensile properties of the treated GF/PTFE composite increased compared with those of the untreated one. RES is superior to SGS/RES and SGS modifiers in promoting interfacial adhesion between the glass fiber and PTFE because of the effects of rare earth elements on the compatibility. Meanwhile, the optimum contents of rare earth elements for the improvement of the tensile properties of GF/PTFE composite were obtained for RES and SGS/RES modifiers. The interfacial adhesion of the GF/ PTFE composites treated with RES or SGS/RES modifiers was mainly controlled by the contents of rare earth elements. The tensile properties of the GF/PTFE composites improved considerably when the content of rare earth elements in surface modifiers was 0.2-0.4wt%, and the optimumtensile performance of GF/PTFE composites was obtained at 0.3wt% RE content.