Effect of PAN-based preoxidized fiber powders addition on structure and properties of carbon foam

Carbon foams were prepared by graphitization from the nascent foams after carbonization,which were prepared by Mitsubishi naphthalene based mesophase pitch containing 2%~8%(mass fraction) PAN-based preoxidized fiber powders with high temperature self-foaming technology.The microstructures and crystal parameters of the carbon foams were characterized by SEM and XRD.The compressive strength and thermal conductivity were also measured.The results show that the maximum density and compressive strengths of graphitized carbon foams are obtained at 2% content of PAN-based preoxidized fiber powders,which are 0.78 g/cm3 and 7.7 MPa,respectively.With increasing the preoxidized fiber powder mass fraction,the pore size of graphitized foam increases,and the bubble holes distribution is less uniform,and the number of microcracks increases,and the order degree of the ligament increases firstly,then decreases.The maximum value of thermal conductivity is 64.78 W.m 1.K 1,and the compressive strength is 6.7 MPa with an addition of 8% preoxidized fiber powders,which increase by 65.3% and 63.4%,respectively,compared with undoped graphited foam.The predominant strengthening mechanism is attributed to the pulling-out effect based on the fiber-matrix interface.