Co-reporter:Liwen Mu;Jian Chen;Yijun Shi;Jiahua Zhu;Huaiyuan Wang;Xiaohua Lu
Journal of Applied Polymer Science 2012 Volume 124( Issue 5) pp:4307-4314
Publication Date(Web):
DOI:10.1002/app.35424
Abstract
The tribological properties and mass loss of polytetrafluoroethylene (PTFE) composites filled with carbon fiber (CF) or potassium titanate whisker (PTW) after the immersion in 30% sulfuric acid solution for 5 or 15 days were studied under different temperatures (25, 50, and 75°C). Results show that PTW/PTFE composites exhibit better anticorrosive and antiwear properties than those of CF/PTFE composites. Acid immersion has no obvious effect on the wear rate of the PTW/PTFE composite. The wear rate of CF/PTFE immersed for 15 days is thrice as much that of untreated composites and 3.6 times as much that of PTW/PTFE composites. Results also indicate that the wear rate of PTFE composites increases with the increasing corrosive mass loss rate and is more dependent on the corrosive mass loss rate rather than the friction coefficient. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Co-reporter:Liwen Mu, Yijun Shi, Xin Feng, Jiahua Zhu, Xiaohua Lu
Tribology International 2012 Volume 53() pp:45-52
Publication Date(Web):September 2012
DOI:10.1016/j.triboint.2012.04.003
In this work, the Finite Element Method is used to simulate and visualize the maximum contact temperature of polymer composites under ring-on-block tribolgical test. The simulated temperatures are in good agreement with the experimental results under all testing conditions. The error values between the experimental and simulated temperature are less than 10%. The contact temperature is decreased to nearly 72 °C just by reduction of the friction coefficient by 40%, which is about 18 times higher than the 40% increase of thermal conductivity. The results indicate that the friction coefficient plays a more important role in the contact temperature than the thermal conductivity.Highlights► A two-dimensional FE model is used to study temperature distributions during sliding. ► Simulated temperatures are in good agreement with experimental results. ► The contact temperature is more dependent on the friction coefficient. ► Temperature difference of lowest thermal conductivity PI composites is the highest.
Co-reporter:Huai-Yuan Wang;Xiao-Hua Lu;Yi-Jun Shi
Journal of Applied Polymer Science 2010 Volume 115( Issue 4) pp:1935-1941
Publication Date(Web):
DOI:10.1002/app.31179
Abstract
The friction and wear properties of poly (ether ether ketone) (PEEK) composites filled with potassium titanate whiskers (PTWs) under alkali, water, and dry conditions were investigated. The wear mechanisms in different lubrication situations were studied on the basis of examinations of the worn and counterpart surfaces with scanning electron microscopy and optical microscopy. The results showed that PTWs could obviously increase the wear resistance and reduce the friction coefficient of the PEEK composites under dry sliding conditions. Only when the PTW content was greater than 35 wt % did the wear resistance and friction coefficient deteriorate. Sliding in water caused increases in the wear rate and friction coefficient of the PEEK composites, and the PTW-filled PEEK composites showed the highest friction coefficient and wear rate under this lubrication condition. On the contrary, sliding in an alkaline solution, the PTW-filled PEEK composites showed the lowest friction coefficient and almost the same level of wear resistance as that found under the dry condition. Furrows and abrasive wear were the main mechanisms for the PTW-filled PEEK composites sliding in water. The transfer onto the counterpart rings was significantly hindered with sliding under water and alkali conditions. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Co-reporter:Jiahua Zhu, Yijun Shi, Xin Feng, Huaiyuan Wang, Xiaohua Lu
Materials & Design 2009 Volume 30(Issue 4) pp:1042-1049
Publication Date(Web):April 2009
DOI:10.1016/j.matdes.2008.06.045
In this study, the artificial neural network is applied to predict tribological properties of carbon fiber and TiO2 particle synergistic reinforced polytetrafluoroethylene (PTFE) composites. Based on a measured database of PTFE composites, wear volume loss and friction coefficient are successfully calculated through a well-trained artificial neural network. Results show that the predicted data are well acceptable when comparing with the real test values under different friction conditions (slight, moderate and rigorous test conditions), and friction coefficient hold a closer correlation with the input parameters than wear volume loss. Three-dimensional plots for tribological properties as a function of test conditions and material compositions were established. Improved results can be obtained from a further optimization of the network and an increasing availability of measurement data.
Co-reporter:Yijun Shi, Xin Feng, Huaiyuan Wang, Xiaohua Lu
Wear 2008 Volume 264(11–12) pp:934-939
Publication Date(Web):10 May 2008
DOI:10.1016/j.wear.2007.06.014
Carbon nanofiber (CNF) was treated with HNO3, coupling agent and HNO3 followed by coupling agent, respectively. The friction and wear properties of surface-treated CNF were investigated on a ring-on-ring friction and wear tester under dry friction conditions. Scanning electron microscopy (SEM) was utilized to study the worn surfaces of PTFE composites. Experimental results showed that surface modification decreased the friction coefficient of CNF/PTFE composites slightly, and reduced the wear volume loss of the PTFE composites obviously. Among all HNO3 treatments, 10 min treatment was the best for the improvement of anti-wear properties of PTFE composites. Moreover, the best anti-wear property of the composite was achieved when CNF was treated with HNO3 followed by coupling agent treatment, which was about 30% lower than that of untreated CNF filled PTFE under 200 N load. SEM studies indicated that surface modification could reduce the abrasive wear of CNF/PTFE composites. And the dispersion of CNF in PTFE composites was also improved after the surface modification, especially for the treatment of HNO3 followed by coupling agent.
Co-reporter:Y.J. Shi, X. Feng, H.Y. Wang, C. Liu, X.H. Lu
Tribology International 2007 Volume 40(Issue 7) pp:1195-1203
Publication Date(Web):July 2007
DOI:10.1016/j.triboint.2006.12.006
In this paper, effects of filler crystal structure and shape on the friction and wear properties of potassium titanate whisker (K2Ti4O9 whisker, K2Ti6O13 whisker), TiO2 whisker and TiO2 particle filled polytetrafluoroethylene (PTFE) composites under dry friction conditions were studied. Meanwhile the influence of filler content, sliding duration, test speed and load were also investigated. Experimental results show that the friction coefficients of various PTFE-based composites are weakly dependent on filler shape but they are more strongly dependent on filler crystal structure. However, for improving the anti-wear property of PTFE, filler crystal structure has less importance than filler shape in the wear-reducing action of PTFE-based composites, and whisker-like filler is better than particle-like filler.
Co-reporter:Yijun Shi;Huaiyuan Wang;Xiaohua Lu
Journal of Materials Science 2007 Volume 42( Issue 20) pp:8465-8469
Publication Date(Web):2007 October
DOI:10.1007/s10853-007-1767-7
Carbon fibers (CF) were surface treated with concentrated HNO3, silane coupling agent, rare earth solution and rare earth sol, respectively. The friction and wear behavior of polytetrafluoroethylene (PTFE) filled with differently surface treated CF were studied. The worn surfaces of CF/PTFE composites were then examined with scanning electron microscope (SEM). It is found that the wear volume loss of the rare earth sol treated CF filled PTFE composites reaches the lowest value when the modifier concentration is 10 wt%. It is only about 65% of the wear volume loss of the PTFE filled with untreated CF. Among all the treatments to CF, rare earth sol treatment is the most effective and the lowest friction and wear volume loss of CF/PTFE composite is exhibited.
Co-reporter:Xin Feng, Xiaosong Diao, Yijun Shi, Huaiyuan Wang, Shenghua Sun, Xiaohua Lu
Wear 2006 Volume 261(11–12) pp:1208-1212
Publication Date(Web):20 December 2006
DOI:10.1016/j.wear.2006.03.005
The friction and wear behavior of polytetrafluoroethylene (PTFE) filled with potassium titanate whiskers (PTW) was studied. It is shown that the friction coefficient of PTW/PTFE composites decreases with the increase of PTW content and with 20 wt% PTW content, the best wear resistance occurs, which is over 1000 times larger than that of pure PTFE. The crystallization of the composite was measured by differential scanning calorimeter (DSC). It reveals that PTW has the ability of inducing heterogeneous nucleation. The degree of crystallization increases initially up to 35 wt% PTW content and then it decreases slightly afterwards. At 35 wt% PTW, the composite has the highest degree of crystallization which is 37% higher than that of pure PTFE. The relationship between the degree of crystallization and the wear behavior was also analyzed which reveals the effect of PTW on PTFE. It is also manifested that the increase of crystallization improves the wear property. Finally, the image of abrasive dust and the worn surface were investigated by optical microscope and SEM, respectively. These observations show that the PTW has the ability to reduce wear by preventing the destruction of PTFE's strap-like structure.
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