TiH₂ Decomposition Kinetics And Preparation Of Aluminum Foam Reinforced By Copper-coated Carbon Fibers

Aluminum foam not only has the characteristics of low density, light weight, high specific strength, but possesses the physical properties such as vibration reduction, damping, sound absorption, sound insulation, heat insulation, electromagnetic shielding, etc., thus, can be widely used in rail transit, construction machinery, chemical metallurgy, electronic communications, aerospace industry and military equipment. Melt direct foaming route is one of the main methods to prepare aluminum foam. It has the characteristics of fairly simple preparation technology, low cost, and can be applied in preparing large-size aluminum foam.According to the problems in preparing aluminum foam by melt direct foaming, the thermal decomposition rule of TiH2 after oxidation treatment was studied. Taking industrial pure aluminum as matrix material, the preparation technology of carbon fiber reinforced aluminum matrix foam material and the influences of different alloy elements on preparing carbon fiber reinforced aluminum matrix foam material were investigated. The morphology of aluminum foam materials was characterized by SEM and XRD, also quasi-static compression performances and energy absorption characteristics were studied. The conclusions can be drawn as follows:(1) Effect of oxidation treatment of TiH2 powder on its gas release is not obvious. Decomposition temperatures of TiH2 powder gradually rise with increased temperature of treated TiH2 whilst content of hydrogen is adversely decreased.(2) Latticed dense oxide film is formed on surface of TiH2 powder after pre-treatment in air. Its thickness is between 1μm and 3μm.The formation of oxide film is progressive process.(3) Technology of Al foams reinforced by carbon fiber shows that the length of carbon fibers has no significant influence on compressive properties. The apparent densities of Al foams go up first and then down with increase of the content of carbon fibers.(4) The thermalphysical performance of carbon fibers/Al composites is obviously alternated as Ca and Mg elements are added into the melt. It is showed that viscosity of the melt increases whilst surface tension goes down. Low densities and highly porous structures of Al foams reinforced by carbon fibers are achieved under these conditions. (5) It is obvious that mechanical properties of Al foams reinforced by carbon fibers, such as plateau stress, initial compaction strain and energy absorption performance etc., increase as the densities of these foams ascend. Furthermore with the increase of the content of carbon fibers, these mechanical properties all appear to rise. However the length of carbon fibers has no significant influence on compressive properties.(6) Brittleness of Al foams with carbon fibers increases in various degrees as the content of carbon fiber and alloying elements ascends. Alteration of Ca and Mg element has little influence on compressive properties of Al foams with approximate densities.