Abrasive wear is a common failure phenomenon that often limits the service life of sealing elements. Evaluation and comparison of the abrasion resistance of polytetrafluoroethylene (PTFE) were conducted using Al2O3par...Abrasive wear is a common failure phenomenon that often limits the service life of sealing elements. Evaluation and comparison of the abrasion resistance of polytetrafluoroethylene (PTFE) were conducted using Al2O3particleswithsizesintherange5to200 μmonapin-on-flattribo-testerunderdryreciprocatingsliding conditions at room temperature. Based on the examined worn surface characteristics of both PTFE and 316L stainless steel (as a counterpart) and the analyzed coefficient of friction (COF) evolutions, the wear mechanism and particle size effect have been explored in detail. The results demonstrate that the abrasive size is the main contributing factor, which can drastically impact the wear mechanism and tribological properties of tribo-pairs. The COF exhibits different evolution characteristics (trends) for different abrasive sizes. For moderate particle sizes, the COF trends become more complicated and the most evident wear of the metallic counterpart is evident. The activity behaviors of abrasives are dominated by the particle size. Particles can becomes embedded in one of the tribo-pair materials to plough-cut the counterpart, thus causing two-body abrasive wear. The abrasives can also behave as free rolling bodies, which play the role of third body to realize three-body "PTFE-abrasive-316L"abrasion. When abrasives are involved in the wear process, both the wear rate and COF of the metallic counterpart increase, but the material removal rate of the PTFE is reduced. The results obtained can offer guidelines regarding the design and protection of seals.展开更多
The effect of elongation of particles in dispersion powders on mechanical performance of polytetrafluoroethylene(PTFE)flat filament is analyzed.Morphology and elongation of particles in four different PTFE dispersion ...The effect of elongation of particles in dispersion powders on mechanical performance of polytetrafluoroethylene(PTFE)flat filament is analyzed.Morphology and elongation of particles in four different PTFE dispersion powders are analyzed.Meanwhile,the correlation between elongation and diameter of dispersion particles is discussed.Strength-elongation curves of PTFE flat filaments made of four different dispersion powders are obtained from measurements of mechanical behaviors.Experimental results show that PTFE flat filament manufactured with dispersion particles having appropriate elongation(0.55-0.60)shows excellent mechanical performance.This work could be regarded as a reference for manufacturing high performance PTFE flat filaments.展开更多
Airborne particulate matter (PM) filter sample processing is susceptible to error and can present issues associated with organizing samples, tracking data, and maintaining weighing conditions. While filter weighing fa...Airborne particulate matter (PM) filter sample processing is susceptible to error and can present issues associated with organizing samples, tracking data, and maintaining weighing conditions. While filter weighing facilities should implement robust quality assurance and control checks to ensure that data collection is accurate and filter storage is secure, mistakes and accidents can still occur that compromise valuable data. This paper presents a novel approach to PM filter sample processing that allows for data validation or data recovery while ensuring data integrity. The technique approximates the original, unused pre-sampling weight of polytetrafluoroethylene (PTFE) filters after PM collection to determine PM mass-deposition (MD). The method describes the extraction of PM loaded on PTFE filters via sonication in relatively non-toxic solvents, methanol and distilled water. The extraction method is compared to the standard gravimetric PM MD determination method for a set of 265 PTFE filters with mean post-sampling filter mass of 116 ± 3.6 mg, mean estimated PM MD using the standard method of 367 ± 589 μg, and mean estimated PM MD using the extraction method of 371 ± 589 μg. A Deming regression comparison of the two methods yields a slope of 0.9983 and a Pearson’s r of 0.999. A Bland-Altman assessment of the percent and absolute differences between the two methods shows the limits of agreement between 32.5% and 25.5% and -61.9 and 50.1 μg, respectively. The 99% confidence interval of the mean difference in mass deposition between the two methods is -5.8 ± 4.5 μg. These data demonstrate that estimating pre-sampling PTFE filter mass by extracting PM from sampled filters is a viable technique for gravimetric filter analysis. This method is of use in recovering pre-sampling filter weights that have been lost, incorrectly measured, or otherwise compromised.展开更多
基金This work was supported by the National Natural Science Foundation of China(Nos.51775503 and 51875343)the Natural Science Foundation of Zhejiang Province(No.LY17E050020)+1 种基金the China Postdoctoral ScienceFoundation(Nos.2017M620152and 2018T110392)Jiangxi Natural Science Foundation of China(20171BCD40009).
文摘Abrasive wear is a common failure phenomenon that often limits the service life of sealing elements. Evaluation and comparison of the abrasion resistance of polytetrafluoroethylene (PTFE) were conducted using Al2O3particleswithsizesintherange5to200 μmonapin-on-flattribo-testerunderdryreciprocatingsliding conditions at room temperature. Based on the examined worn surface characteristics of both PTFE and 316L stainless steel (as a counterpart) and the analyzed coefficient of friction (COF) evolutions, the wear mechanism and particle size effect have been explored in detail. The results demonstrate that the abrasive size is the main contributing factor, which can drastically impact the wear mechanism and tribological properties of tribo-pairs. The COF exhibits different evolution characteristics (trends) for different abrasive sizes. For moderate particle sizes, the COF trends become more complicated and the most evident wear of the metallic counterpart is evident. The activity behaviors of abrasives are dominated by the particle size. Particles can becomes embedded in one of the tribo-pair materials to plough-cut the counterpart, thus causing two-body abrasive wear. The abrasives can also behave as free rolling bodies, which play the role of third body to realize three-body "PTFE-abrasive-316L"abrasion. When abrasives are involved in the wear process, both the wear rate and COF of the metallic counterpart increase, but the material removal rate of the PTFE is reduced. The results obtained can offer guidelines regarding the design and protection of seals.
基金Shanghai Economic and Information Technology Commission,China(No.HUCXY-2014-025)
文摘The effect of elongation of particles in dispersion powders on mechanical performance of polytetrafluoroethylene(PTFE)flat filament is analyzed.Morphology and elongation of particles in four different PTFE dispersion powders are analyzed.Meanwhile,the correlation between elongation and diameter of dispersion particles is discussed.Strength-elongation curves of PTFE flat filaments made of four different dispersion powders are obtained from measurements of mechanical behaviors.Experimental results show that PTFE flat filament manufactured with dispersion particles having appropriate elongation(0.55-0.60)shows excellent mechanical performance.This work could be regarded as a reference for manufacturing high performance PTFE flat filaments.
文摘Airborne particulate matter (PM) filter sample processing is susceptible to error and can present issues associated with organizing samples, tracking data, and maintaining weighing conditions. While filter weighing facilities should implement robust quality assurance and control checks to ensure that data collection is accurate and filter storage is secure, mistakes and accidents can still occur that compromise valuable data. This paper presents a novel approach to PM filter sample processing that allows for data validation or data recovery while ensuring data integrity. The technique approximates the original, unused pre-sampling weight of polytetrafluoroethylene (PTFE) filters after PM collection to determine PM mass-deposition (MD). The method describes the extraction of PM loaded on PTFE filters via sonication in relatively non-toxic solvents, methanol and distilled water. The extraction method is compared to the standard gravimetric PM MD determination method for a set of 265 PTFE filters with mean post-sampling filter mass of 116 ± 3.6 mg, mean estimated PM MD using the standard method of 367 ± 589 μg, and mean estimated PM MD using the extraction method of 371 ± 589 μg. A Deming regression comparison of the two methods yields a slope of 0.9983 and a Pearson’s r of 0.999. A Bland-Altman assessment of the percent and absolute differences between the two methods shows the limits of agreement between 32.5% and 25.5% and -61.9 and 50.1 μg, respectively. The 99% confidence interval of the mean difference in mass deposition between the two methods is -5.8 ± 4.5 μg. These data demonstrate that estimating pre-sampling PTFE filter mass by extracting PM from sampled filters is a viable technique for gravimetric filter analysis. This method is of use in recovering pre-sampling filter weights that have been lost, incorrectly measured, or otherwise compromised.
