X-ray microtomography reconstruction - High temperature transient diffusion - Material: High alumina-silicate refractory

Diffusion tests were performed with solid diffusants of iron oxides in porous silico-aluminous refractory castables in high temperature conditions. A non-destructive X-ray computer microtomography technique with digital 3D reconstruction (3DCT) was used for spatial monitoring the diffusion into the media. A particle tracking (PT) method was applied to predict diffusion through porous materials and to quantify its diffusive properties based on 3D images over time. The influence of temperature was examined ranging from 1100°C to 1300°C, at exposure time of 100h. High alumina-silicate refractory materials were used: M1 (non-doped). The high-density components (HDC) and Pores were extracted in the images from the cross-sections of the microtomography process and converted into monochromatic 8-bit image to quantify the concentration of the diffusants and pores.

The sequential junction of all microtomographic digital slices shows the diffusion concentration profile along the depth of the samples. There are approximately 350-400 digital microtomographic slices for each temperature (1100°C, 1200°C, 1250°C. 1275°C and 1300°C). Thus, this process provides the diffusion penetration profile (diffusivity) in the medium as a function of temperature and, therefore, a diffusional mathematical model.

本研究针对高温条件下多孔硅铝质耐火浇注料中的氧化铁固态扩散剂开展扩散测试。采用搭载数字三维重建技术的无损X射线显微计算机断层扫描（3DμCT）方法，对扩散剂在介质内的空间扩散过程进行监测。同时采用粒子追踪（PT）方法，基于时序三维图像预测多孔材料内的扩散行为，并量化其扩散性能。

试验设置保温时长100小时，考察了1100℃至1300℃区间内温度对扩散过程的影响；所用试样为高铝硅质耐火材料M1（未掺杂组）。从显微断层扫描的截面图像中提取高密度组分（HDC）与孔隙特征，并将其转换为单色8位图像，用于量化扩散剂与孔隙的浓度分布。

将全部显微断层扫描数字切片按序列拼接后，可得到试样沿深度方向的扩散浓度分布轮廓。每个温度条件下（1100℃、1200℃、1250℃、1275℃与1300℃）约包含350~400张数字显微断层切片。由此，该试验流程可得到介质内扩散渗透轮廓（扩散率）随温度的变化规律，进而可建立扩散过程的数学模型。