据我们所知, 微硅粉能有效提高混凝土的抗压性能, 弯曲, 防渗、防腐蚀, 以及为什么能起到这么好的效果, 与微硅粉的物理化学特性密不可分, 今天 高铁 介绍微硅粉的物理和化学性质.
硅粉的产生
我们知道 微硅粉 是工业硅及硅铁合金在高温熔炼过程中排出的烟气或由烟气净化装置回收的工业粉尘, 高纯石英的形成过程是在高温状态下还原的, 将有 10% 到 15% 硅形成蒸气进入烟道, silicon vapor with the airflow up to meet oxygen combined into silicon monoxide (Si0), escaping from the furnace when the SiO meets cold air, combined with oxygen into silicon dioxide (二氧化硅) flue gas.
These SiO2 flue gases are condensed into very small spherical non-crystalline micro-beads, which are discharged from the chimney in the form of dust, and are collected when they pass through the collection equipment, which is silica fume, and the whole reaction formula is as follows.
二氧化硅(quartz)+C→Si↓+CO2
2Si+O2→2SiO↑
2SiO+O2→2SiO2(微硅粉)↑
The physical and chemical properties of silica fume
Chemical composition of silica fume
The chemical composition of silica fume is very simple, 85~96% of the part is SiO2, and the majority is amorphous silica, 这是一种很好的火山灰材料. 无定形SiO2含量对微硅粉的性质起决定性作用, 少量氧化铁, 氧化铝, 氧化钙, 氧化硫和氧化钠 (钾), ETC. 对混凝土伤害不大; 碳含量不超过 2%, 燃烧损失约为 1.5% 到 3%, 硅粉比重为2.20-2.30.
硅粉的矿物成分
硅粉基本上是无定形二氧化硅, 含有少量二氧化硅结晶矿物 (主要是石英). 无定形二氧化硅结构和细颗粒是硅粉高活性的主要原因. 特殊优质硅粉, 其无定形二氧化钙含量高达 98% 或者更多.
硅粉颗粒组成和形貌
硅粉在烟道快速冷却过程中, 由于液体表面张力的作用, 无定形球形颗粒的形成, the surface is extremely smooth. As the micro-silica powder particles are very fine and the surface chemical bonding defects and rarely exist alone, often multiple small particles are gathered together through electrostatic force to form a flocculent structure or agglomerate structure.
The particle size of silica fume is very small, generally below 0.5μm, spherical particles of uneven size, the average particle size is only 0.10~0.20μm, the specific surface area of 15000~30000m2/kg. the particle size of silica fume is much smaller than cement, 粉煤灰, 矿粉, ETC。, about 1/50~1/100 of the particle size of cement.
