The properties of resin transfer molding(RTM)cyanate ester and its T800 grade carbon fiber composites were studied with the rheometer,differential scanning calorimetry(DSC),FT-IR,dynamic mechanical analyzer(DMA),therm...The properties of resin transfer molding(RTM)cyanate ester and its T800 grade carbon fiber composites were studied with the rheometer,differential scanning calorimetry(DSC),FT-IR,dynamic mechanical analyzer(DMA),thermal gravimetric analysis(TGA),mechanical property testing,and scanning electron microscopy(SEM).The results showed that the temperature of cyanate ester suitable for RTM process was 70℃.Curing process of the resin was 130℃/2 h+160℃/2 h+200℃/2 h+220℃/4 h.Glass transition temperature and heat decomposition temperature of the cured resin are 289℃and 415℃,respectively.Mechanical properties of T800/RTM cyanate composites are 13.5%higher than that of T700/RTM cyanate composites and equal to that of T800/Prepreg cyanate composites.Tg of T800/RTM cyanate composites was proved to be 291℃.Fracture pattern of the composites was flat,which proved excellent interface properties between fiber and resin in this composite.展开更多
Cementites decomposition of a pearlitic ductile cast iron during graphitization annealing heat treatment was investigated.Fractographies and microstructures of heat treated samples were observed using a scanning elect...Cementites decomposition of a pearlitic ductile cast iron during graphitization annealing heat treatment was investigated.Fractographies and microstructures of heat treated samples were observed using a scanning electron microscope and mechanical properties were measured by a universal tensile test machine.The results indicated that during isothermal annealing at 750°C,the tensile strength of pearlitic ductile cast iron was increased to a peak value at 0.5h,and decreased gradually thereafter but the elongation was enhanced with the increase of annealing time.Moreover,the diffusion coefficient of carbon atoms could be approximately calculated as 0.56μm2/s that could be regarded as the shortrange diffusion.As the holding time was short（0.5h）,diffusion of carbon atoms was incomplete and mainly occurred around the graphites where the morphology of cementites changed from fragmentized shape to granular shape.In addition,the ductile cast iron with tensile strength of 740MPa and elongation of 7% could be achieved after graphitization annealing heat treatment for 0.5h.Two principal factors should be taken into account.First,the decomposition of a small amount of cementites was beneficial for increasing the ductility up to elongation of 7%.Second,the diffusion of carbon atoms from cementites to graphites could improve the binding force between graphites and matrix,enhancing the tensile strength to 740 MPa.展开更多
文摘The properties of resin transfer molding(RTM)cyanate ester and its T800 grade carbon fiber composites were studied with the rheometer,differential scanning calorimetry(DSC),FT-IR,dynamic mechanical analyzer(DMA),thermal gravimetric analysis(TGA),mechanical property testing,and scanning electron microscopy(SEM).The results showed that the temperature of cyanate ester suitable for RTM process was 70℃.Curing process of the resin was 130℃/2 h+160℃/2 h+200℃/2 h+220℃/4 h.Glass transition temperature and heat decomposition temperature of the cured resin are 289℃and 415℃,respectively.Mechanical properties of T800/RTM cyanate composites are 13.5%higher than that of T700/RTM cyanate composites and equal to that of T800/Prepreg cyanate composites.Tg of T800/RTM cyanate composites was proved to be 291℃.Fracture pattern of the composites was flat,which proved excellent interface properties between fiber and resin in this composite.
基金supported by the Program for Innovative Research Team in University of Liaoning Province(Grant No.LT2015020)National Natural Science Foundation of China(Grant No.51274142)
文摘Cementites decomposition of a pearlitic ductile cast iron during graphitization annealing heat treatment was investigated.Fractographies and microstructures of heat treated samples were observed using a scanning electron microscope and mechanical properties were measured by a universal tensile test machine.The results indicated that during isothermal annealing at 750°C,the tensile strength of pearlitic ductile cast iron was increased to a peak value at 0.5h,and decreased gradually thereafter but the elongation was enhanced with the increase of annealing time.Moreover,the diffusion coefficient of carbon atoms could be approximately calculated as 0.56μm2/s that could be regarded as the shortrange diffusion.As the holding time was short（0.5h）,diffusion of carbon atoms was incomplete and mainly occurred around the graphites where the morphology of cementites changed from fragmentized shape to granular shape.In addition,the ductile cast iron with tensile strength of 740MPa and elongation of 7% could be achieved after graphitization annealing heat treatment for 0.5h.Two principal factors should be taken into account.First,the decomposition of a small amount of cementites was beneficial for increasing the ductility up to elongation of 7%.Second,the diffusion of carbon atoms from cementites to graphites could improve the binding force between graphites and matrix,enhancing the tensile strength to 740 MPa.
