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The structure, the mechanical and tribological properties of PEI-based composites reinforced with chopped carbon fibers and simultaneously loaded with solid lubricant fillers of various nature (PTFE, graphite) were investigated under both point and linear contact conditions. It was shown that their tribological properties could be improved by the formation of a transfer film on the friction surfaces. This process was determined by the chemical activity of the solid lubricant filler and the scheme of the tribological contact. [ABSTRACT FROM AUTHOR]

In this research, both two- and three-component composites based on thermoplastic polyethersulfone (PES) filled with solid lubricant fillers of various sizes and nature (PTFE, graphite, and MoS2) were investigated. Their structure, the mechanical and tribological properties were studied under point-contact conditions according the "ball-on-disk" scheme. It was shown that the "PES +10 wt.% PTFE +0.5 wt. % MoS2" composite possessed the lowest both wear rate and friction coefficient levels (0.75 and 0.61 mm3/N·m as well as 0.034 and 0.044, respectively, for the metal and ceramic counterparts). In these cases, there was a near-wearless mode due to the formation of a homogeneous transfer film. Both graphite and MoS2 microparticles did not play the role of solid lubricants in the investigated PES-based composites under the studied conditions. [ABSTRACT FROM AUTHOR]

In this study, the formation of laminated composites based on PEEK plates and prepregs from carbon fiber (CF) fabric and the PEEK binder were investigated. The varying parameters were the prepreg thickness (and the binder content as a result), as well as the ultrasonic welding (UW) duration. Their optimization enabled to obtain a uniform structure in the fusion zone without any damages of the CF-fabric, causing improved strength properties. It was shown that the prepreg thickness determined its ability to melt upon the investigated UW durations. In the case of the thinnest prepreg of 280 µm with the minimal binder content, the homogeneous low-defect interface had been formed. However, its fracture occurred by the tear mechanism. In the case of the thicker 460 µm prepreg, the UW joint was able to maintain its integrity in the shear tests at the high stress level, while the UW joint failure was along the interface between the UW joint and the base material. At the maximum studied UW duration, the prepreg had been melted and the CF-fabric had been damaged, as well as a significant number of defects (pores) had been formed at the interface. This had caused the increased withstand stresses in the shear test due to the interface reinforcement, but the formation of such a structure is unacceptable in real products. Finally, options for practical implementations of the obtained results were discussed. [ABSTRACT FROM AUTHOR]

A comparative analysis on the structure, mechanical and tribological properties of multicomponent polymer composites “UHMWPE + 17 wt % HDPE-g-SMA + 12 wt % PP” fabricated by fused deposition modeling (layer-by-layer extrusion printing) and hot pressing (compression sintering) was carried out. It is shown that extrudable UHMWPE based composites fabricated by 3D-printing over the set of key tribomechanical properties (wear resistance, friction coefficient, elastic modulus, yield point, tensile strength, elongation at break) exceeds those of the composites obtained by compression sintering (CS). The reason of the latter is associated with the formation of a more uniform ordered permolecular structure with increased degree of crystallinity. Multicomponent antifriction nanocomposites with the extrudable polymer-polymer matrix (filled with hydroxyapatite and carbon fibers) were fabricated and investigated. The results obtained make it possible to recommend the multicomponent UHMWPE-based nanocomposites for manufacturing complex shape products for tribotechnical applications by means of 3D-printing. [ABSTRACT FROM AUTHOR]

Mechanical and tribological properties of UHMWPE-based composites with various fillers (aluminum oxyhydroxide micron sized powder, wollastonite microfibers, chopped glass fibers) were studied. The fillers were functionalized with commercially available silane-containing KH550 modifier in order to increase adhesion to the matrix. A comparison on the coupling agent effect on the mechanical and tribological properties of UHMWPE composites loaded at the fillers variation of the content and size is carried out. It is shown that fillers’ functionalization is an efficient way to increase wear resistance of UHMWPE composites filled with powders and fibers (increase in wear resistance makes from 1.5 to 3.6 times). On the basis of obtained results, UHMWPE based composites with various size/content studied fillers (powder, fiber) functionalized with the coupling KH550 agent are recommended for industrial application in a wide range of loads and sliding velocities. [ABSTRACT FROM AUTHOR]

Mechanical and tribological properties of UHMWPE composites with the different initial polymer powder size filled with chopped glass fibers (CGF) functionalized with silane-containing KH550 modifier aimed at increase adhesion were studied. It is shown that the various initial powder size at an equivalent molecular weight determines the pattern of glass fiber distribution in the matrix, and, as a consequence, the mechanical and tribotechnical properties of the composites. It was revealed that glass fiber reinforced composite based on fine UHMWPE powder grade GUR-2122 possesses higher tribomechanical properties in contrast with coarse grade GUR-4120 one. For practical antifriction applications the “UHMWPE 2122 + 10 wt. % CGF” composite is recommended loaded with the glass fibers functionalization with the KH550 silane-based industrially manufactured coupling agent. [ABSTRACT FROM AUTHOR]

Mechanical and tribological properties of polyimide (PI) based composites with solid lubricant fillers (polytetrafluoroethylene (PTFE) and molybdenum disulfide) were studied at testing over various counterparts (metallic and ceramic). It is shown that PTFE is an efficient solid lubricant filler for polyimide which increases wear resistance of the composites up to 100 times as compared to neat polymer due to the formation of a transfer film on the metallic counterface. At the same time, despite its solid lubricating “status” molybdenum disulfide particles acts as microabrasive decreasing wear resistance under dry sliding friction, while at the content of 5 wt % MoS2 loading does not ensure maintenance of mechanical properties at the level of neat polymer. Two-component composite “PI + 15 wt % PTFE” is recommended as an efficient antifriction material for metal-polymer and ceramic-polymer friction pairs. [ABSTRACT FROM AUTHOR]

A comparative analysis on the structure, mechanical and tribological properties of the multicomponent polymer-polymeric composites "UHMWPE + 15 wt.% HDPE-g-SMA + 15 wt.% PP" fabricated by Fused Deposition Modeling (layer-by-layer extrusion printing) and hot pressing (compression sintering) was carried out. It is shown that extrudable UHMWPE composites fabricated by 3D–printing over the set of key tribomechanical properties (wear resistance, friction coefficient, elastic modulus, yield point, tensile strength, a value of elongation at break) exceed those of the composites obtained by compression sintering (CS). The reason of the latter is associated with the formation of a more uniform ordered permolecular structure with increased crystallinity. This makes it possible to recommend this material for the manufacturing complex shape products for tribotechnical applications by means of 3D-printing. [ABSTRACT FROM AUTHOR]

Changes of the microstructure and phase composition of selective laser melting Ti-6Al-4V titanium alloy samples during ultrasonic impact post-processing were investigated by optical, transmission microscopy, and X-ray analysis. Significant refinement of the microstructure in the thin surface layer was observed as a result of ultrasonic impact treatment. This causes an increase in microhardness and strength characteristics of the surface layer of selective laser melting samples under uniaxial tension. [ABSTRACT FROM AUTHOR]

Tribomechanical properties of ultrahigh molecular weight polyethylene (UHMWPE) composites filled with chopped glass fiber (CGF) functionalized by two silane-containing modifiers in order to increase the adhesion between the filler and a non-polar matrix have been investigated. A comparison between two commercially available adhesion promoters (Penta 1006 and KH550) was carried out, and their effectiveness was shown from the standpoint of increasing the wear resistance of composites (more than 2 times) in a wide range of loads and sliding velocities. [ABSTRACT FROM AUTHOR]