Synthesis Of Mesophase Pitch-Derived Graphitized Foam And Its Modification Research

As a novel three-dimension-orderly porous carbon material,carbon foam has many excellent performances such as low density,high strength,oxidation resistance,wave-absorbing,energy absorbing,acid-alkali resistance,low expansion coefficient and high thermal conductivity etc.These excellent properties made carbon foam applied in many fields such as aerospace,aerospace,commercial and civil materials and so on.In this paper,AR mesophase pitch was used as the raw material.Firstly,studied on the effect of foaming heating rate,holding time and pressure on the structure and physical properties of carbon foam,and the optimum technological parameters for the preparation of carbon foam were determined.On this basis,carbon foams were prepared by adding graphite,graphene and boric acid into mesophase pitch.The effects and mechanisms of additives on the structure and properties of carbon foams were studied.The results show as follow:(1)By analyzing the scanning electron microscope(SEM)graph of carbon foam prepared at different heating rates,holding temperatures and time in the foaming process,and the structure of the carbon foams prepared by the heating rate of 5 C/min,the foaming temperature of 450 C and the foaming time of 2 h was best;(2)With the increase of foaming pressure,the volume density and compressive strength of the prepared graphite foam increased,and the thermal conductivity first increased and then decreased,when the initial foaming pressure was 2MPa,the maximum value of compressive strength of the graphite foam reached 40.6 W/(m·K);(3)The content of flake graphite had a significant effect on the physical properties of graphite foam.With the increased of flake graphite content,the compressive strength of graphite foam increased obviously,and the thermal conductivity firstly increased and then decreased;(4)The volume density of carbon foam increased with the increase of graphene content.NWhen the graphene content is 0.9 wt%,the compressive strength and thermal conductivity reach the maximum value of 1.58 MPa and 64.27 W/(m·K)respectively;(5)The bulk density of graphite foam modified by boric acid increased with the increase of boric acid content.When the boric acid content is 5 wt%9 the compressive strength of the graphite foam is 3.56 MPa and the thermal conductivity is 80.6 W/(m·K).