Fabrication And Compressive Property Of Carbon Nanotube Reinforced Aluminum Composite Foams

The aluminum(Al)foams have attracted increasing attention because of their low density and superior performances such as energy absorption,sound absorption and vibration reduction,which meet the applications in the fields of automotive and aerospace industries.Al composite foams reinforced by ceramic particles efficiently enhance the compressive property compared with Al foams.However,the addition of ceramic particles introduces more deformation brittleness,also results in the decrease of energy absorption efficiencies and poor bonding between the matrix and th e reinforcements.Due to their low density,excellent mechanical and electrical properties,carbon nanotubes(CNTs)have been regarded as the ideal reinforcement for composites.In this paper,a novel method combined in-situ CVD,short-time ball milling and spaceholder technique were used to fabricate CNT/Al composite foams.The effect of ball milling process on the CNT/Al composite powders was investigated.The parameter of compacting and sintering process and the microstructure and mechanical property of CNT/Al composite foams were characterized.Experimental results show that,the CNTs with mean length of 2-5 ?m were successfully obtained by the CVD in-situ process on the surface of Al powders;the compressive property was obviously affected by the ball milling rate and ball milling time,and the CNTs were deeply embedded inside the Al powder after ball milling at certain speed and time.The optimum ball milling parameters were 400 rpm,90min or 500 rpm,60min.The optimum compacting and sintering parameters were researched.Comparison between “dissolution-sintering” process and “direct-sintering” process shows that,the compressive property of the composite foams fabricated by “dissolution-sintering” process was higher than that of the composite foams fabricated by “dissolutionsintering” process,and the composite foams possessed uniformly distributed and well-tailored pores.With increasing the CNT content,the compressive property and energy absorption capacity of CNT/Al-composite foams enhanced obviously,and the composite foams owned the best compressive property when CNT content reached 3wt.%.The compressive property would drop with further increasing CNT content because the CNTs could not be uniformly embedded inside the Al powder by the short-time ball milling.