Haitao YE
,
Olivier GAUDIN
,
Richard B.JACKMAN
,
null
,
null
,
null
材料科学技术（英）
The first measurement of impedance on free-standing diamond films from 0.1 Hz to 10 MHz up to 300℃ were reported. A wide range of chemical vapour deposition (CVD) materials were investigated, but here we concentrate on `black' diamond grown by microwave plasma enhanced CVD (MWPECVD). The Cole-Cole (Z' via Z'') plots are well fitted to a RC parallel circuit model and the equivalent resistance and capacitance for the diamond films have been estimated using the Zview curve fitting. The results show only one single semicircle response at each temperature measured. It was found that the resistance decreases from 62 MΩ at room temperature to 4 kΩ at 300℃, with an activation energy around 0.51 eV. The equivalent capacitance is maintained at the level of 100 pF up to 300℃ suggesting that the diamond grain boundaries are dominating the conduction. At 400℃, the impedance at low frequencies shows a linear tail, which can be explained that the AC polarization of diamond/Au interface occurs.
关键词:
Black diamond
,
diamond
,
Impedance
,
spectroscopy
,
Act
刘卓峰
,
肖加余
,
江大志
,
彭超义
,
曾竟成
高分子材料科学与工程
采用等温和非等温差示扫描量热(DSC)对Huntsrnan1564/3486低黏度环氧树脂体系的固化反应进行了研究,建立了修正的Oliviei固化度唯象模型,用于描述恒温条件下固化度温度时间关系.模型计算值与实验值符合良好.监测了基于实际工程应用背景85mm厚复合材料单面模具加热固化过程中制件厚度方向的温度情况,针对该过程提出了基于修正Olivier模型的适用于变温条件的时间离散分步计算法,并计算了固化过程厚度方向的固化度分布.
关键词:
环氧树脂
,
固化反应
,
唯象模型
