沉积温度对碳/碳复合材料密度均匀性的影响

INFLUENCE OF DEPOSITION TEMPERATURE ON DENSITY UNIFORMITY OF CARBON/CARBON COMPOSITES

采用快速化学液相气化渗透法制备了二维碳/碳复合材料。用Leica定量金相分析仪及Archimedes排水法测定了不同沉积温度制备的样品沿径向的孔隙率及密度分布,同时用扫描电子显微镜观察了样品的低倍形貌及孔隙率分布。实验结果表明:定量金相观察计算得到的孔隙率值略大于排水法测得的孔隙率值;当沉积温度≤1200℃,随着沉积温度的升高,沉积得到的材料残留孔隙率降低,密度升高,样品沿径向密度分布比较均匀,基本上不存在密度梯度或分布不均匀现象。沉积温度为1250℃时,孔隙分布也比较均匀,但样品内残留孔隙较多且大。

2D-carbon/carbon composites were fabricated by a rapid chemical liquid-vaporized infiltration (CLVI) processing. Pores and density along the radial direction of the composite sample deposited at different temperatures were measured by means of Leica quantitative metallography and Archimedes principle methods. Morphologies and pores of the composites were observed by scanning electron microscopy. The results indicate that the porosity obtained by quantitative metallography is slightly higher than that measured by the Archimedes principle. When the deposition temperature is equal to or less than 1200°C, with the increase of the deposition temperature the residual porosity decreases, the density of the composite increases and the density along the radial direction exhibits uniform distribution. However, the pore distribution of the composite deposited at 1250°C is uniform, but there are many more and much larger residual pores in these samples.