Papers by Keyword: Friction and Wear

Abstract: TiB₂-TiN composite films/SiC films (SiC films as interlayer) were deposited on biomedical titanium alloy (Ti6Al4V) through magnetron sputtering technique. The friction/wear behaviors of the TiB₂-TiN composite films under Kokubo simulation body fluid (SBF) were investigated. The results show that as sliding against Si₃N₄ ball (4 mm in diameter) at 200g load, the TiB₂-TiN composite films exhibited the superior friction/wear properties with the friction coefficient of 0.22, the special wear rate in the magnitude order of 10⁻⁶ mm³ m⁻¹ N⁻¹ together without interface delaminating. It was found that the films exhibited navel adhesion to Ca and P elements in Kokubo SBF. The present results demonstrate the possibility of developing the surface modification procedure of combining superior wear resistance and good osseointegration for application of orthopaedic implants.

Abstract: The nano-indentation response and the friction and wear properties of the CNx/SiC (carbon nitride /silicon carbon) double layer thin films (SiC films as interlayer) deposited on nanocrystalline titanium substrate using magnetron sputtering technique at room temperature were investigated. The results show that the CNx films exhibited a low nano-hardness of 8.0 GPa and Young's modulus of 55.0 GPa but a high hardness-to-modulus ratio of 0.146. As sliding against Si₃N₄ (silicon nitride) ball under Kokubo simulation body fluid (SBF) at room temperature, the CNx films exhibited the superior tribological properties with the friction coefficients of about 0.1 and the special wear rate of about 1.6×10⁻⁶ mm³/Nm.

Abstract: The aim of this work is the evaluation of the effects of PA6 content on the friction andwear properties of POM composite system. Friction andwear properties of PA6/POM composite were determined with the help of pin-on-disc tribometer in sliding contact with a steel-ball at room temperature without lubrication. The spectroscopic investigations reveal that the increasing concentration of PA6 has a drastic influence on crosslinking efficiency due to their interference with POM in curing process. As a result, POM filled PA6 with higher concentration showed remarkably enhanced friction and wear properties.

Abstract: The present study establishes the relationships between the carbon fibers (CF) content and the trbological properties of Polyether ether ketone (PEEK) composite. PEEK composites such as unreinforced PEEK, reinforced PEEK with different content of carbon fibres were used for the tribological tests. The results indicated that CF/PEEK composite had better tribological properties than pure PEEK. Some CF was ground and squeezed, then mixed with debris on the worn surface, which improved the wear resistance greatly. The low friction coefficient of CF/PEEK composite caused little change in the temperature and further ensured the stable state of sliding.

Abstract: To reduce the friction coefficient between impregnated diamond bit and rock, experiments on addition of graphite to the matrix material of bit cutters were conducted. The cutters were made up of diamond contained working layers and binding layers. The friction and wear properties of cutters and binding layers were investigated using a pin-on-disc friction & wear tester with granite as tribopair. The results showed that with addition of graphite, the hardness and friction coefficient of binding layer decreased, but its wear resistance increased; compared to cutters without graphite, those cutters containing graphite had lower wear loss and friction coefficient and their sliding wear process was much steadier, but diamond protrusion was still normal.

Abstract: TiNi alloyed layer was prepared on surface of Ti6Al4V substrate by plasma surface alloying process. Micro-structure, composition distribution, phase structure and hardness distributing of TiNi modified layer were analyzed. Tribological performance of TiNi alloyed layer and Ti6Al4V substrate was observed by Pin-on-disc test. The results indicated that surface microhardness of TiNi alloyed layer was about 620HV. Coefficient of friction (CoF) and relative wear rate (RWR) of TiNi alloyed layer were lower than Ti6Al4V substrate, and wear resistance of TiNi alloyed layer was improved obviously. The wear mechanism of Ti6Al4V alloy is abrasion and adhesion wearing, while TiNi alloyed layer shows abrasion wearing.

Abstract: A wear-resistant SiC (silicon carbon) film on titanium substrate was prepared by magnetron sputtering technology. The film exhibits low nano-hardness of 12.1 GPa and low Young's modulus of 166.2 GPa together with superior friction/wear properties. As sliding against Si₃N₄ (silicon nitride) ball (2 mm in radius) at room temperature under Kokubo simulation body fluid condition, the film exhibited the friction coefficient of about 0.215 and the special wear rate in the order of magnitude of 10⁻⁵ mm³/ Nm even at the load of 500g without film cracking and interface delaminating. The high film-cracking and interface-delaminating resistance is due to the low hardness of the film and the good film/substrate modulus match caused by the low elastic modulus of the film.

Abstract: At annealing temperature, Al-Mg alloys have grain boundary and surface magnesium segregation and their strength are also impossibly enhanced by heat treatment. Friction and wear properties of cold-rolled 5052 aluminum alloy annealed at different temperature were studied in this paper. X-ray diffract analysis(XRD) indicates that metallurgical phase has no obvious transformation with different annealing temperature. Auger electron (AE) fines that magnesium segregation and oxide layer thickness of surface are different along the plate thickness direction at different annealing temperatures. Results show that the higher oxide layer of the surface, the smaller wear can be got. Friction and wear testing shows that 5052 aluminum alloy annealed at different temperatures almost have the same coefficient of friction under the same experimental condition , but the coefficient friction of the same sample will increase while temperature rises.

Abstract: In this paper, a novel no-asbestos brake composite reinforced by natural bamboo fibers is studied. The bamboo fibers are modified by heat treatment, alkali treatment and coupling treatment respectively. Tribological performance of different fibers reinforced composites are developed by means of friction test and microstructure observation. The results show that heat treatment of bamboo fibers at 140 for 4 hours makes the friction and wear characteristics of brake composites more stable than the untreated ones, but poor wear resistance at low temperature and heat fade still exist. There is no significant change on fiber surface. The alkali treatment of 17% NaOH solution for 12 hours contributes to desirable combination of higher friction coefficients and lower wear rates, and the surface morphology shows a number of deep grooves that avail the interface bonding. The effect of coupling treatment with KH550 on tribological performance of composites have the similar rule to that of the alkali treated ones except of heat fade, and the fiber surface is evenly coated with the coupling agent, which enhances the bonding of fibers and resin but fails at elevated temperature.

Abstract: The hybrid Kevlar/PTFE(polytetrafluroethylene) fabric composites filled with different nano-Tio2 content of matrix resin were fabricated. To determine the tribological properties, the filled and unfilled composites sliding against 45 steel were performed on MM-200 friction and wear tester. Scanning electron microscopy(SEM) was utilized to examine the morphology of worn surface. Differential scanning calorimetry (DSC) analysis was also performed to study the thermal properties of the composites. The results show that the addition of nano-Tio2 improve the wear resistance and decrease the friction coefficient. The friction coefficient become unconstant during test with the increase of nano-Tio2 in the resin matrix, and the optimum fraction of nano-Tio2 in the resin is 1wt%. The SEM observations indicat that microcutting and plastic deformation are the main wear mechanisms. DSC analysis that there is no significant change in the melting points, and that there has been minimum chemical interaction between the resin matrix and nano-Tio2.