凝胶注模制备的铝铜坯体脱脂过程及动力学

通过凝胶注模工艺,采用非水基凝胶体系,成功地制备铝铜坯体.通过扫描电镜观察脱脂前聚合物完全包裹粉末颗粒,脱脂后金属坯体中聚合物完全脱除.通过反应机理得出聚合物三维网络结构的化学式.采用热分析手段、热重和红外连用系统分析金属坯体的脱脂过程,根据Coats-Redfern方法对非等温热失重率曲线的数据进行动力学研究,建立动力学方程.在不同的升温速率下聚合物脱脂反应级数为1,活化能在79.86-108.63 k J·mol^-1范围内,指前因子反应指数在106-107min^-1,活化能的结果表明反应对温度和动力学比较敏感.脱脂主要分为两个阶段,在240-350℃主要是聚合物链段的分解,在350-470℃主要是聚合物网状结构的解聚和解交联反应,同时脱脂阶段主要产生CO₂、CO、NO₂和H₂O挥发性气体.

Thermal degradation mechanism and kinetics of aluminum-copper green bodies prepared by gelcasting

Aluminum-copper green bodies were successfully prepared by a non-aqueous gelcasting system. Scanning electron microscopy observations showed that the powder particles were completely wrapped by the polymer before degreasing,and the polymer in the metal body was completely removed after degreasing. A three-dimensional network polymer structure was obtained by the reaction mechanism. The degreasing process of the metal body was investigated by means of differential scanning calorimetry,thermogravimetry-derivative thermogravimetry and thermogravimetry-Fourier transform infrared spectroscopy. The kinetic equations and parameters were gotten according to Coats-Redfern method for non-isothermal weight loss curves. The results indicate that at different heating rates the reaction order is 1,the activation energy and pre-exponential factor are ranging from 79.86 to 108.63 kJ·mol-1 and 106 to 107 min-1,respectively. The activation energy reaction is sensitive to temperature and dynamics. The degreasing process is divided into two stages:a slight weight loss over a wide temperature range of 240-350℃ is due to the random chain scission and the main weight loss around 380 to 425℃ is attributed to depolymerization of monomers from the main chains and decrosslinking of the network polymer. The emissions of CO₂,CO,NO₂ and H₂O are identifled during the degreasing process.