| Rubber seals are one of the key components of the three major systems of aircraft fuel,hydraulic and environmental control systems.Due to the action of high pressure and wide temperature range,rubber seals are prone to aging,resulting in seal failure,which not only affects the operation and efficiency of the three systems,but also affects the flight safety of the aircraft in severe cases.Fluororubber is a kind of rubber compound commonly used in rubber seals.Hot oil aging phenomenon is widespread and affects the working performance of rubber seals.Therefore,it is of great significance to carry out the research on hot oil aging of fluororubber.The main research contents of this paper are as follows:Firstly,taking the FX-17 fluororubber commonly used in aviation systems as the research object,the commonly used No.15 aviation hydraulic oil is selected as the aging immersion medium.According to GB/T 2941-2006 Rubber-General procedures for preparing and conditioning test pieces for physical test methods,the FX-17 accelerated aging test conditions designed 7 different temperatures(23 ?,70 ?,100 ?,125 ?,150 ?,175 ?,200 ?)and 7 different soaking times(1 d,3 d,7 d,14 d,21 d,28 d,35 d).Secondly,the mechanical properties of hot oil aged FX-17 were tested and evaluated by testing mechanical properties such as tensile strength,elongation at break,100 % modulus,tear strength,compression set and hardness change rate.The results show that with the increase of aging temperature and the prolongation of aging time,the tensile strength,elongation at break,100 % modulus and tear strength of aged FX-17 decrease as a whole,and the compression set is increased.The trend is that the surface hardness of the aged FX-17 dumbbell specimen is gradually reduced,and the hardness of the end face of the pressure-aged A-shaped cylinder specimen is gradually decreased,and the circumferential hardness is gradually increased.Again,field emission scanning electron microscopy,energy spectrum analyzer,Fourier transform infrared spectroscopy and thermogravimetric analyzer were used to analyze the fracture fracture morphology,fracture element content,chemical molecular structure and thermal stability of FX-17 before and after aging.The results show that with the deepening of the aging,the fracture form changes,the additive inside the rubber material is precipitated,and the content of the additive element near the outer part of the fracture gradually decreases with the increase of temperature,the oxidation reaction is continuously enhanced,and the molecular chain structure occurs.The fracture and the thermal stability decrease,resulting in a general decline in mechanical properties.Finally,the compression set and tensile strength data obtained from the aging test were used as the evaluation indexes.The storage life of FX-17 was predicted using standard method and variable activation energy method respectively,and the prediction results were compared,verified and discussed.The results show that the life prediction with compression set as the evaluation index and variable activation energy method are more reasonable. |
PDF Full Text Request