【作者】 杨东辉；

【导师】 何德坪；

【作者基本信息】 东南大学 ， 材料加工工程， 2005， 博士

【摘要】 泡沫铝合金在高技术和民用领域中有重要应用。针对泡沫铝合金制备的现存问题,需要揭示发泡剂氢化钛的产气规律,以供研究和控制铝合金熔体的泡沫化过程,从而成功制备具有独特性能的泡沫铝合金。本文制备了小孔径(D<1mm)、低孔隙率(65%<Pr<75%)泡沫铝合金。建立了金属管道结构氩载气流中的程序升温分解装置,利用该装置首次测得了氢化钛的程序升温热分解谱图。首次全面地将程序升温脱附的相关理论成功地应用于程序升温分解反应(这些理论包括:谱线重叠法、查表法和等反应速率法),并将查表法的可应用范围拓展到峰巅温度Tm=300～1100K和活化能Ed=100～740kJ/mol。利用这些理论,结合定温预分解差谱技术,解叠了氢化钛的程序升温热分解谱线,首次求得了氢化钛热分解反应动力学参数和动力学方程组。据此方程组,计算得到了在940K时,氢化钛的热分解量对时间的关系线,它与铝合金熔体泡沫化过程相吻合。首次为研究和控制铝合金熔体泡沫化过程提供了理论依据。首次提出了测定铝合金熔体泡沫孔结构参数的“瞬时冻结”凝固法。研究发现:在一定的搅拌时间内,熔体泡沫的孔隙率保持恒定。在该搅拌时间范围内,当搅拌时间短时,待分解的氢化钛就多,制得的样品的孔隙率就大;当搅拌时间长时,待分解的氢化钛就少,制得的样品的孔隙率就小。据此规律,成功地制得了小孔径(D<1mm)、低孔隙率(65%<Pr<75%)泡沫铝合金试样。经测定,该试样具有高的屈服强度和比刚度、大的表观杨氏模量和大的压缩吸能能力,有望成为高技术领域中的一种性能卓越的新材料。更多还原

【Abstract】 Al alloy foam is a kind of new material which has important applications in both high-tech and civil fields. To counter the existing problem in preparing Al alloy foam, it is necessary to reveal the rule of hydrogen production from thermal decomposition of titanium hydride, which furnishes the basis for studying and controlling the Al alloy melt foaming process, thus successfully preparing Al alloy foam with excellent features. In this paper, the Al alloy foam with small pore diameter (D<1mm) low porosity (65% <Pr <75%) is successfully prepared.A temperature programmed decomposition (TPD) apparatus with metal tube structure, in which Ar is used as the carrier gas, is established. It is we, YANG Donghui, HE Deping and YANG Shangrun, who have firstly recorded the TPD spectrum of titanium hydride by using the TPD apparatus.It is the first to completely apply the related theories of temperature programmed desorption, which include spectrogram superposition method, consulting table method (CTM) and isodesorption rate method, to temperature programmed decomposition, and to broaden the application range of CTM to the peak maximum temperature Tm=300~1100K and the activation energy Ed=100~740kJ/mol. The TPD spectrum of titanium hydride is separated and simulated into individual peaks by utilizing these theories in combination with differential spectrum technique and a set of thermal decomposition kinetics equations are acquired. According to these equations, the relationship between decomposition quantity and time for titanium hydride at the temperature of 940K is obtained, which well coincides with the Al alloy melt foaming process. So it is these equations that firstly furnish the theoretical basis for studying and controlling the Al alloy melt foaming process.It is the first to advance the“instant freezing”solidification method to determine the pore structure parameters of Al alloy melt foam. It has been revealed that the porosity of Al alloy melt foam keeps constant in a proper stirring period. In this period, the stirring time is shorter the amount of titanium hydride to be decomposed is larger and the porosity of the prepared sample is higher; on the contrary, the stirring time is longer the amount of titanium hydride to be decomposed is smaller and the porosity of the prepared sample is lower. According to this rule, a set of samples of Al alloy foam with small pore diameter (D<1mm) and low porosity (65%<Pr<75%), possessing high yielding strength, high specific stiffness, high apparent Young’s modulus and large compression energy absorption capacity, have been prepared successfully. This kind of Al alloy foam is expected to be used in both high-tech and civil fields as a new material with excellent feature.更多还原