Since the resin-based composite materials are of essential importance in many key engineering fields,the manufacture processes are highly worth studying and optimizing for satisfying quality control at the highest pos...Since the resin-based composite materials are of essential importance in many key engineering fields,the manufacture processes are highly worth studying and optimizing for satisfying quality control at the highest possible production rate.In this paper,combined with the impregnation theory,the flow-thermal-mechanical multiphysics coupling model is built to characterize,investigate and optimize the osmotic flow process of hot-melt resin in fiber fabrics with the uniformity and adequacy of resin impregnation as the evaluation criteria.First,the osmotic flow process is characterized by the osmotic flow front of resin,which is tracked by the phase-field method.Then,the influencing factors of roller clearance,temperature and speed are comprehensively investigated.After that,the simulation data of resin impregnation degree are fitted by polynomial curves,with accuracy up to 96.13%,for further investigation of interaction between influencing factors.Finally,based on the above results,the operation parameter combination for impregnation process is optimized with the response surface method and provided as the guidance for practical application.展开更多
The objective of this research was to develop a novel self-lubricating coating on an AA6061 aluminum alloy.Three coatings were prepared by the plasma electrolytic oxidation（PEO） process using 50-, 500-, and 1000-Hz ...The objective of this research was to develop a novel self-lubricating coating on an AA6061 aluminum alloy.Three coatings were prepared by the plasma electrolytic oxidation（PEO） process using 50-, 500-, and 1000-Hz pulsed direct current, respectively. The as-deposited coatings were then post-treated using two different methods, viz., ultrasonic vibration-aided vacuum oil impregnation（UVOI） and oil impregnation under ambient pressure（OIAP）. After posttreatment, an oil-containing, self-lubricating top layer was formed on the coatings. The effects of the coatings＇ surface morphologies and structures on their oil-holding capabilities were discussed. The results revealed that coatings prepared with higher frequency had a greater oil-holding capacity using OIAP post-treatment, while those prepared with lower frequency had a greater oil-containing capability using UVOI post-treatment. These phenomena are related to the morphologies of the coatings produced with various current modes. The tribological properties of the coatings before and after post-treatments were investigated by pin-on-disc sliding wear tests. Due to the formation of a lubricant-containing top layer, the post-treatment coatings had a lower friction coefficient and improved wear resistance compared with the asdeposited coatings. In addition, the coatings after UVOI treatment had better wear performance than those post-treated using the OIAP process. Among all coatings, the coating produced with a 50-Hz pulsed current followed by UVOI posttreatment achieved the lowest friction coefficient（0.03） and best wear resistance when sliding against a Si3N4 ceramic counterface. This study indicates that a novel self-lubricating coating can be prepared by a PEO process combined with vacuum oil impregnation post-treatment.展开更多
基金financially supported by the National Natural Science Foundation of China(52176202)。
文摘Since the resin-based composite materials are of essential importance in many key engineering fields,the manufacture processes are highly worth studying and optimizing for satisfying quality control at the highest possible production rate.In this paper,combined with the impregnation theory,the flow-thermal-mechanical multiphysics coupling model is built to characterize,investigate and optimize the osmotic flow process of hot-melt resin in fiber fabrics with the uniformity and adequacy of resin impregnation as the evaluation criteria.First,the osmotic flow process is characterized by the osmotic flow front of resin,which is tracked by the phase-field method.Then,the influencing factors of roller clearance,temperature and speed are comprehensively investigated.After that,the simulation data of resin impregnation degree are fitted by polynomial curves,with accuracy up to 96.13%,for further investigation of interaction between influencing factors.Finally,based on the above results,the operation parameter combination for impregnation process is optimized with the response surface method and provided as the guidance for practical application.
基金financially supported by the National Natural Science Foundation of China (No. 51301153)the National Undergraduate Training Programs for Innovation and Entrepreneurship of China (201410345022)
文摘The objective of this research was to develop a novel self-lubricating coating on an AA6061 aluminum alloy.Three coatings were prepared by the plasma electrolytic oxidation（PEO） process using 50-, 500-, and 1000-Hz pulsed direct current, respectively. The as-deposited coatings were then post-treated using two different methods, viz., ultrasonic vibration-aided vacuum oil impregnation（UVOI） and oil impregnation under ambient pressure（OIAP）. After posttreatment, an oil-containing, self-lubricating top layer was formed on the coatings. The effects of the coatings＇ surface morphologies and structures on their oil-holding capabilities were discussed. The results revealed that coatings prepared with higher frequency had a greater oil-holding capacity using OIAP post-treatment, while those prepared with lower frequency had a greater oil-containing capability using UVOI post-treatment. These phenomena are related to the morphologies of the coatings produced with various current modes. The tribological properties of the coatings before and after post-treatments were investigated by pin-on-disc sliding wear tests. Due to the formation of a lubricant-containing top layer, the post-treatment coatings had a lower friction coefficient and improved wear resistance compared with the asdeposited coatings. In addition, the coatings after UVOI treatment had better wear performance than those post-treated using the OIAP process. Among all coatings, the coating produced with a 50-Hz pulsed current followed by UVOI posttreatment achieved the lowest friction coefficient（0.03） and best wear resistance when sliding against a Si3N4 ceramic counterface. This study indicates that a novel self-lubricating coating can be prepared by a PEO process combined with vacuum oil impregnation post-treatment.
