天然掺杂铁氧体的电磁参数调控机制分析及其在吸波材料中的应用

对不同地质产状类型天然铁氧体的电磁参数测量结果发现，岩浆岩型（A型）天然铁氧体的电磁参数明显区别于其他类型铁氧体，是一种可用于微波吸收材料的天然矿物．该矿物经选矿工艺制备后，在8～12GHz频率范围内，ε′=58．60，ε″=10．0，μ′=1．2～1．5，μ″=1．0～1．2，属于具有一定磁导率、低介电常数、高电磁损耗的磁性物质，其粉体适合作为吸波材料的磁性吸收剂．对A型天然铁氧体的矿物组成和化学成分的分析结果表明，与单一磁铁矿或二元型铁矿物组成的天然铁氧体相比，A型天然铁氧体中的杂质元素和另相矿物含量明显高于其他天然铁氧体，其中的杂质成分对电磁参数起着重要的调控作用，这种调控作用有利于降低吸波材料的反射系数，并提高电磁波吸收效率．而且，A型铁氧体中的这种天然掺杂导致的结构缺陷及其对电磁参数的影响效应是人工制备的铁氧体难以实现的．材料应用试验与吸波性能测量结果表明，以A型天然铁氧体作为粉体填料与天然橡胶制成的吸波片材在8～12GHz频率范围内的电磁波吸收频宽和反射系数均优于传统的羰基铁粉与橡胶制成的吸波片材，完全可以替代羰基铁粉应用于微波吸收材料的开发，而且具有原料丰富、制备工艺简单、成本低、吸波性能稳定的比较优势．

Effect of the Copper and Iron Concentration on Gum Formation in Gas Oil of Baiji Refinery

In this research, the affect of storage time and different metals concentration of copper and iron on gum formation in gas oil is investigated. A study of the affect of gum content on properties of sample is performed, where the gas oil derived from （Kirkuk crude oil） have boiling point range （266-420）℃. For this purpose, a gas oil sample has been doped with these two metals ions at concentration levels of 0.5, 1.5, 2.5 and 3.5 μg mL-1. Washed gum content tests have been carried out using ASTM D-381 on samples stored for 8, 16, 24 and 32 days. The experimental results show that an increase in storage time and metal concentration strongly increases the rate of gum formation for all metal investigations and this increase in gum concentration affects the viscosity of samples towards increasing of viscosity.