Brake wear is an important but unregulated vehicle-related source of atmospheric particulate matter(PM).The single-particle spectral fingerprints of brake wear particles(BWPs)provide essential information for understa...Brake wear is an important but unregulated vehicle-related source of atmospheric particulate matter(PM).The single-particle spectral fingerprints of brake wear particles(BWPs)provide essential information for understanding their formation mechanism and atmospheric contributions.Herein,we obtained the single-particle mass spectra of BWPs by combining a brake dynamometer with an online single particle aerosol mass spectrometer and quantified real-world BWP emissions through a tunnel observation in Tianjin,China.The pure BWPs mainly include three distinct types of particles,namely,Bacontaining particles,mineral particles,and carbon-containing particles,accounting for 44.2%,43.4%,and 10.3%of the total BWP number concentration,respectively.The diversified mass spectra indicate complex BWP formation pathways,such as mechanical,phase transition,and chemical processes.Notably,the mass spectra of Ba-containing particles are unique,which allows them to serve as an excellent indicator for estimating ambient BWP concentrations.By evaluating this indicator,we find that approximately 4.0%of the PM in the tunnel could be attributable to brake wear;the real-world fleet-average emission factor of 0.28 mg km1 veh1 is consistent with the estimation obtained using the receptor model.The results presented herein can be used to inform assessments of the environmental and health impacts of BWPs to formulate effective emissions control policies.展开更多
The experiment is conducted on MM-1000 friction test machine, which tests friction wear property of copper-based brake materials by powder metallurgy at different brake speeds. It shows that the coefficient of frictio...The experiment is conducted on MM-1000 friction test machine, which tests friction wear property of copper-based brake materials by powder metallurgy at different brake speeds. It shows that the coefficient of friction and wear volume are greatly influenced by brake speed. When the brake speed is 4000 r/min, which is a bit higher, the material still has a higher coefficient of friction with 0.47. When the brake speed is over 4000r/min, the coefficient of friction decreased rapidly. When the brake speed is 3000r/min, the material’s wear is in its minimum. That is to say no matter how higher or lower the brake speed is the wear volume is bigger relatively. With the brake speed of the lower one it mainly refers to fatigue wear; while of higher one it mainly refers to abradant and oxidation wear.展开更多
The use of asbestos material is being avoided to manufacture the brake pads as it is harmful and toxic in nature. Further it leads to various health issues like asbestosis, mesothelioma and lung cancers. These brake p...The use of asbestos material is being avoided to manufacture the brake pads as it is harmful and toxic in nature. Further it leads to various health issues like asbestosis, mesothelioma and lung cancers. These brake pads can be replaced by natural fibers like Palm kernel (0-50%), Nile roses (0-15%) and Wheat (0-10%) with additives like aluminum oxide (5%-20%) and graphite powder (10%-35%). Phenolic resin of 35% is utilized as a binder. Particulated Nile roses are used to increase the friction coefficient and wheat powder is used to reduce the wear rate. Aluminum oxide and graphite are abrasive in nature. This helps to make brake pads with high friction co-efficient and less wear rate with low noise pollution. The wear of the proposed composites have been investigated at different speeds. Various tests like wear on pin-ondisc apparatus, hardness on the Rockwell hardness apparatus and oil absorption test have been conducted. Phenolic resin produces good bonding nature to fiber. Thus, Fibers found to have performed palatably among all commercial brake pads. The objective of the research indicates that Palm kernal shell could be a conceivable alternative for asbestos in friction coating materials.展开更多
Friction-wear properties of the ZrSiO4 reinforced samples were measured and compared with those of plain bronze based ones. For this purpose, density, hardness, friction coefficient wear behaviour of the samples were ...Friction-wear properties of the ZrSiO4 reinforced samples were measured and compared with those of plain bronze based ones. For this purpose, density, hardness, friction coefficient wear behaviour of the samples were tested. Microstructures of samples before and after sintering and worn surfaces were also investigated by scanning electron microscopy （SEM）, and the wear types were determined. The optimum friction-wear behaviour was obtained in the sample compacted at 500 MPa and sintered at 820℃. Density of the final samples decreased with increasing the amount of reinforcing elements （ZrSiO4） before pre-sintering. However after sintering, there is no change in density of the samples including reinforcing elements （ZrSiO4）. With increasing friction surface temperature, a reduction in the friction coefficient of the samples was observed. However, the highest reductions in the friction coefficients were observed in the as-received samples containing 0. 5% reinforced ZrSiO4. The SEM images of the sample indicated that while bronze-based break lining material without ZrSiO4 showed abrasive wear behaviour, increasing the amount of ZrSiO4 resulted a change in abrasive to adhesive wear mechanism. All samples exhibited friction-wear values, which were within the values shown in SAE-J661 standard. With increasing the amount of reinforcing ZrSiO4, wear resistance of the samples was increased. However samples reinforced with 5% and 6% ZrSiO4 showed the best results.展开更多
To verify the effect of Al_2O_3 particle content and size as an abrasive on resin matrix friction materials for mining equipment, the tribological performance of friction materials was studied by using a blockon-ring ...To verify the effect of Al_2O_3 particle content and size as an abrasive on resin matrix friction materials for mining equipment, the tribological performance of friction materials was studied by using a blockon-ring tribotester over a wide range of applied load and sliding speed. The testing conditions simulated brake conditions of mining equipment. The antiwear property of nano-Al_2O_3 was superior to that of micro-Al_2O_3 for friction materials. The friction coefficients of specimens increased with the increase of nano-Al_2O_3 content. The wear rates decreased with increasing nano-Al_2O_3 content. The wear rates of specimens containing nano-Al_2O_3 was about 2-8 times lower than that of specimen with micro-Al2O3. The specimen with 10.5 vol% nano-Al_2O_3 showed the best tribological properties. The wear mechanism of specimens with nano-Al_2O_3 was abrasive wear and plastic deformation.展开更多
The SiCp/Al-alloy composite front brake rotors designed for Shanghai Santana cars were prepared by semi-solid stirring+liquid forging process. The composite brake rotors were subjected to dynamometer tests on a SCHENC...The SiCp/Al-alloy composite front brake rotors designed for Shanghai Santana cars were prepared by semi-solid stirring+liquid forging process. The composite brake rotors were subjected to dynamometer tests on a SCHENCK brake testing system, referring to TL110 standard of VOLKSWAGEN Co. The friction coefficient and thermal response during fade testing and the wear performance of the composite rotors were studied as the functions of various parameters such as braking pressures, initial speeds, initial temperatures, torque and decelerations, and were compared with those of conventional cast iron rotors. The results show that the properties of the composite rotors can achieve the requirements of commercial cast iron rotors. The results also show that the friction coefficients of the composite rotors under different braking conditions are within the deviation band specified by the TL110 standard, and the temperature rise of composite rotors is lower than that of cast iron rotors at the end of each fade stop. The wear resistance of composite rotors is higher than that of cast iron rotors. The friction mechanism and wear mechanism were analyzed.展开更多
The thermal cracking and wear mechanism of rail wheel tread have been studied.The results showed that the thermal cracking of rail wheel tread is related to the chemical composition (mainly the carbon content)and the ...The thermal cracking and wear mechanism of rail wheel tread have been studied.The results showed that the thermal cracking of rail wheel tread is related to the chemical composition (mainly the carbon content)and the hardness of the wheels.When the composite braking shoes are used,the rate of wear of the wheel tread is related to the fracture toughness of the newly-formed“white layer”i.e.the martensite.The thermal cracking proof wheels(55SiMn) so far developed has achieved significant operating results in practical use.展开更多
This study focuses on the characterization of train brake blocks. The brake blocks are an essential organ of train speed control system to ensure comfort and safety to passengers and crew. However, poor quality soles ...This study focuses on the characterization of train brake blocks. The brake blocks are an essential organ of train speed control system to ensure comfort and safety to passengers and crew. However, poor quality soles can cause a premature wear of the wheels whose consequences are on the one hand, a damaged brake function, and also high repair costs. Samples were carried out on 3 different batches of brake blocks. Their metallurgical characterization consisted of a study of the hardness and microstructural analysis (microstructures and chemical analyzes) of the different samples. The results show that the hardness of some soles is greater than that of the wheel, mainly associated with a cementite microstructure. This can lead to a premature wear of the wheels at the expense of brake blocks.展开更多
基金supported by the National key research and development program of China(2022YFE0135000)the Tianjin Science and Technology Plan Project(19YFZCSF00960)+2 种基金the National Natural Science Foundation of China(42177084,42175123,42107114,42107125)the Natural Science Foundation of Tianjin(20JCYBJC01270)the Fundamental Research Funds for the Central Universities(63221411).
文摘Brake wear is an important but unregulated vehicle-related source of atmospheric particulate matter(PM).The single-particle spectral fingerprints of brake wear particles(BWPs)provide essential information for understanding their formation mechanism and atmospheric contributions.Herein,we obtained the single-particle mass spectra of BWPs by combining a brake dynamometer with an online single particle aerosol mass spectrometer and quantified real-world BWP emissions through a tunnel observation in Tianjin,China.The pure BWPs mainly include three distinct types of particles,namely,Bacontaining particles,mineral particles,and carbon-containing particles,accounting for 44.2%,43.4%,and 10.3%of the total BWP number concentration,respectively.The diversified mass spectra indicate complex BWP formation pathways,such as mechanical,phase transition,and chemical processes.Notably,the mass spectra of Ba-containing particles are unique,which allows them to serve as an excellent indicator for estimating ambient BWP concentrations.By evaluating this indicator,we find that approximately 4.0%of the PM in the tunnel could be attributable to brake wear;the real-world fleet-average emission factor of 0.28 mg km1 veh1 is consistent with the estimation obtained using the receptor model.The results presented herein can be used to inform assessments of the environmental and health impacts of BWPs to formulate effective emissions control policies.
基金supported by fund of China Academy of Engineering Physics(421010201)supported by fund of outstanding youngth of Henan Provincesupported by important research project of Henan Province(03230239000).
文摘The experiment is conducted on MM-1000 friction test machine, which tests friction wear property of copper-based brake materials by powder metallurgy at different brake speeds. It shows that the coefficient of friction and wear volume are greatly influenced by brake speed. When the brake speed is 4000 r/min, which is a bit higher, the material still has a higher coefficient of friction with 0.47. When the brake speed is over 4000r/min, the coefficient of friction decreased rapidly. When the brake speed is 3000r/min, the material’s wear is in its minimum. That is to say no matter how higher or lower the brake speed is the wear volume is bigger relatively. With the brake speed of the lower one it mainly refers to fatigue wear; while of higher one it mainly refers to abradant and oxidation wear.
文摘The use of asbestos material is being avoided to manufacture the brake pads as it is harmful and toxic in nature. Further it leads to various health issues like asbestosis, mesothelioma and lung cancers. These brake pads can be replaced by natural fibers like Palm kernel (0-50%), Nile roses (0-15%) and Wheat (0-10%) with additives like aluminum oxide (5%-20%) and graphite powder (10%-35%). Phenolic resin of 35% is utilized as a binder. Particulated Nile roses are used to increase the friction coefficient and wheat powder is used to reduce the wear rate. Aluminum oxide and graphite are abrasive in nature. This helps to make brake pads with high friction co-efficient and less wear rate with low noise pollution. The wear of the proposed composites have been investigated at different speeds. Various tests like wear on pin-ondisc apparatus, hardness on the Rockwell hardness apparatus and oil absorption test have been conducted. Phenolic resin produces good bonding nature to fiber. Thus, Fibers found to have performed palatably among all commercial brake pads. The objective of the research indicates that Palm kernal shell could be a conceivable alternative for asbestos in friction coating materials.
文摘Friction-wear properties of the ZrSiO4 reinforced samples were measured and compared with those of plain bronze based ones. For this purpose, density, hardness, friction coefficient wear behaviour of the samples were tested. Microstructures of samples before and after sintering and worn surfaces were also investigated by scanning electron microscopy （SEM）, and the wear types were determined. The optimum friction-wear behaviour was obtained in the sample compacted at 500 MPa and sintered at 820℃. Density of the final samples decreased with increasing the amount of reinforcing elements （ZrSiO4） before pre-sintering. However after sintering, there is no change in density of the samples including reinforcing elements （ZrSiO4）. With increasing friction surface temperature, a reduction in the friction coefficient of the samples was observed. However, the highest reductions in the friction coefficients were observed in the as-received samples containing 0. 5% reinforced ZrSiO4. The SEM images of the sample indicated that while bronze-based break lining material without ZrSiO4 showed abrasive wear behaviour, increasing the amount of ZrSiO4 resulted a change in abrasive to adhesive wear mechanism. All samples exhibited friction-wear values, which were within the values shown in SAE-J661 standard. With increasing the amount of reinforcing ZrSiO4, wear resistance of the samples was increased. However samples reinforced with 5% and 6% ZrSiO4 showed the best results.
基金Funded by the National Natural Science Foundation of China(No.51405329)the China Postdoctoral Science Foundation(No.2015M570239)
文摘To verify the effect of Al_2O_3 particle content and size as an abrasive on resin matrix friction materials for mining equipment, the tribological performance of friction materials was studied by using a blockon-ring tribotester over a wide range of applied load and sliding speed. The testing conditions simulated brake conditions of mining equipment. The antiwear property of nano-Al_2O_3 was superior to that of micro-Al_2O_3 for friction materials. The friction coefficients of specimens increased with the increase of nano-Al_2O_3 content. The wear rates decreased with increasing nano-Al_2O_3 content. The wear rates of specimens containing nano-Al_2O_3 was about 2-8 times lower than that of specimen with micro-Al2O3. The specimen with 10.5 vol% nano-Al_2O_3 showed the best tribological properties. The wear mechanism of specimens with nano-Al_2O_3 was abrasive wear and plastic deformation.
文摘The SiCp/Al-alloy composite front brake rotors designed for Shanghai Santana cars were prepared by semi-solid stirring+liquid forging process. The composite brake rotors were subjected to dynamometer tests on a SCHENCK brake testing system, referring to TL110 standard of VOLKSWAGEN Co. The friction coefficient and thermal response during fade testing and the wear performance of the composite rotors were studied as the functions of various parameters such as braking pressures, initial speeds, initial temperatures, torque and decelerations, and were compared with those of conventional cast iron rotors. The results show that the properties of the composite rotors can achieve the requirements of commercial cast iron rotors. The results also show that the friction coefficients of the composite rotors under different braking conditions are within the deviation band specified by the TL110 standard, and the temperature rise of composite rotors is lower than that of cast iron rotors at the end of each fade stop. The wear resistance of composite rotors is higher than that of cast iron rotors. The friction mechanism and wear mechanism were analyzed.
文摘The thermal cracking and wear mechanism of rail wheel tread have been studied.The results showed that the thermal cracking of rail wheel tread is related to the chemical composition (mainly the carbon content)and the hardness of the wheels.When the composite braking shoes are used,the rate of wear of the wheel tread is related to the fracture toughness of the newly-formed“white layer”i.e.the martensite.The thermal cracking proof wheels(55SiMn) so far developed has achieved significant operating results in practical use.
文摘This study focuses on the characterization of train brake blocks. The brake blocks are an essential organ of train speed control system to ensure comfort and safety to passengers and crew. However, poor quality soles can cause a premature wear of the wheels whose consequences are on the one hand, a damaged brake function, and also high repair costs. Samples were carried out on 3 different batches of brake blocks. Their metallurgical characterization consisted of a study of the hardness and microstructural analysis (microstructures and chemical analyzes) of the different samples. The results show that the hardness of some soles is greater than that of the wheel, mainly associated with a cementite microstructure. This can lead to a premature wear of the wheels at the expense of brake blocks.
