Fabrication Of1D Nano Aluminia Via Simple Liquid-phase Method And Its Sintering Behavior

In the paper，one-dimensional(1D) nano-aluminum with different length-diameterratio were synthesized via simple、 low-cost liquid-phase method utilizing differentprecipitant and aluminium sources. In addition，the sintering behavior of1D aluminum andnano-Al2O3(100nm) were also studied. The main researches are as followed:(1) Taking the NaSiO3as precipitating agent and AlCl3as aluminium sources, theinfluence of concentration of NaSiO3on products’ morphology was discussed.1Dγ-AlOOH can obtained when the the molar ratio of NaSiO3to AlCl3is ranged from1to10-400at180℃for16h. It is found that the samples have an average diameter of50nmwith a length of700-800nm and the length-diameter ratio reach to14-16:1. After heattreatment in air at600℃for2h, the phase transformation from γ-AlOOH to γ-Al2O3wasoccurred and the similar morphology was obtained. Taking Na3PO4as precipitating agentand Al(NO3)3as aluminium sources, the influence of concentration of Na3PO4on products’morphology were discussed.1D γ-AlOOH were obtained when the molar ratio of Na3PO4to Al(NO3)3is ranged from1to103at180℃for24h. The1D γ-AlOOH have an averagediameter of150nm with a length of1.5-2um and the length-diameter ratio reach to10-13:1. When the molar ratio of Na3PO4to Al(NO3)3is changed to1~10-100, thebundle-like γ-AlOOH were obtained at180℃for24h. The bundle’s length is about2~4um and width is about0.5~1um. a white precursor precipitate were synthesized by usingNaOH and Al(NO3)3as raw material at170℃for24h. With a subsequent heat treatment inair at600℃for2h,1D γ-Al2O3with an average diameter of10nm and a length of2umhas obtained; the length-diameter ratio is reach about200:1.1D γ-AlOOH can alsosynthesized at200℃for24h by only using aluminium sources as raw material. Theproducts have an average diameter of170nm with a length of12um; the length-diameterratio is7:1.(2) The formation mechanism of1D rod-like γ-AlOOH was investigated. At first, thecolloids Al(OH)3would be formed through the reaction of Al3+and OH-in solution. Withsubsequent increase in reaction time, γ-AlOOH was obtained from the early formed Al(OH)3colloids. Because of the weak hydrogen bonds and the surface OH-bond inducedinteraction between the solvent molecules, the layer structure of AlOOH tends to curl,leading to the formation of1-D γ-AlOOH nanorod via the rolling mechanism. (3)The Al2O3-ZrO2composites were sintered through rapid sintering preparationmethods. The sintering behavior of1D Al2O3was also discussed. It shows that： when thesintering conditions were taken under80MPa pressure at1300℃for3min with the highheating rate(1300℃/min), the density of10wt%Al2O3-ZrO2matrix composites containing(length-diameter ratio=7:1) reach nearly98%.The alumina grain was shown in shortcolumn shape with a length of1.5um and the dispersibility is very well. Under the samesintering condition, the10wt%Al2O3-ZrO2matrix composites containing (nano-Al2O3100nm) were also sintered, the alumina grain gathered seriously and no rod-like grain wasformed in the composites matrix. From the observation of prefabricated crack, the directionof the crack will make a lot of changes due to the the existence of1D nano-aluminastructure, but the-Al2O3(100nm) have little impact on the change in the direction of crackpropagation direction.