木材/二氧化硅复合材料的微细构造

为弄清木材/二氧化硅复合材料的微细构造，通过固体膨胀率与增重率的关系、吸湿处理中尺寸变化、X射线衍射分析(XRD)、扫描电子显微镜分析(SEM)及能量色散X射线分析(EDAX)等方法，研究了该复合材料的微观构造特性.结果表明:①木材/二氧化硅复合材料的增重率与含水率成正相关.固体膨胀率随着增重率的增加而增加，弦向固体膨胀率大于径向.尺寸变化率随着增重率的增加而减小.②SEM分析表明，二氧化硅凝胶存在于木材细胞空隙中.EDAX分析表明，气干材、水调湿材制备的木材/二氧化硅复合材料，二氧化硅存在于木材细胞壁中，硅的质量百分含量分别为4.11%、9.22%；饱水材制备的木材/二氧化硅复合材料，二氧化硅存在于细胞壁及细胞腔中，硅的质量百分含量为17.07%.③XRD分析表明，二氧化硅存在于木材细胞壁中，生成的二氧化硅凝胶越多，结晶度越小. 

Microstructure of wood_silicondioxide composite.

In order to know completely the microstructure of wood_silicon dioxide composite,the authors analyzed the relationship between cell wall expansion percentage and weight gain percentage(WGP),and the dimensional changes during moisture absorption treatment.We used the following techniques or instruments in our analyses: Xray diffraction(XRD),scanning electron microscopy(SEM) and energy dispersive X-ray analyzer(EDAX).Results included: 1) WGP was proportional to the moisture content of pretreated wood.Cell wall expansion percentage increased with the increase of WGP and tangential cell wall expansion percentage was higher than radial expansion.There was a slightly negative correlation between the percentage of dimensional change and WGP during the moisture absorption treatment.2) SEM analysis showed that silicon dioxide occupied free space of wood.EDAX analysis showed that silicon dioxide was found in cell wall of wood for the air-dried and moistening pretreatment of wood,and in both cell wall and cell cavity for the water saturated wood.The percentages of quality silicon in wood-silicon dioxide composite prepared from air-dried,moistening and water saturated wood were 4.11%,9.22% and 17.07%.3) XRD analysis showed that silicon dioxide was also found in cell wall of wood.Its crystallinity decreased with an increase of silicon dioxide content in wood_silicon dioxide composite.