铜锌连续测定

矿石中铜锌连续测定,一般均用氯化铵-氢氧化铵-溴水分离铁、锰碘量法,它测定铜肯定可得到准确结果:但测定锌则有下列缺点:1.铜干扰锌的测定,滴定铜后需过滤分离碘化亚铜,由于部分亚铜与碘化钾生成碘化亚铜络合物,过滤时并不能将铜完全除尽。2.镉干扰测定,而含锌矿石中,一般均含镉。3.高铁氰化钾-碘化钾-锌的反应不是单一的,除生成K_2Zn_3[Fe(CN)_6]_2外,还生成Zn_2[Fe(CN)_6],计算结果时,换算因素只能由实验确定。4.加入高铁氰化钾后,由于反应速度较慢,需放置5     

含羧基的席夫碱型聚硅氧烷液晶的合成及其液晶性能

对羟基苯甲醛与对胺基苯甲酸缩合制得刚性基元（1）;3-溴丙烯与对羟基苯甲酸经取代反应制得对烯丙氧基苯甲酸（2）; 2经加成和酰氯化后,与1经酯化反应合成了含羧基的席夫碱型聚硅氧烷液晶（5）,其结构经IR确证。对5的液晶性能进行了测试。结果表明：5属于近晶型条带织构; 5具有较高的熔点和清亮点温度,液晶区间在180.34～251.11 ℃。     

多晶铁纤维的合成与微波吸收性能的研究

The preparation and microwave-absorbing behavior of polycrystalline iron fibers modified with the thermal decomposition of carbonyl iron were studied in this paper. Through preparation of α-FeOOH fiber precursor, dehydration, reduction with hydrogen, modification with the thermal decomposition of carbonyl iron and passivation, polycrystalline iron fibers were yielded. α-FeOOH fiber precusor with optimum diameter and aspect ratio was made by using uniform seed crystal with optimum concentration and controlling the reaction time. Lacunas from procedure of dehydration and reduction were well modified with carbonyl iron. The sample with 1.95 mm thickness containting 60 % by weight of modified polycrystalline iron fibers showed reflection loss over 10 dB within the frequency range of 8.5～14.6 GHz, and the maximum reflection loss was 21.8 dB at 11.3GHz, while the sample of nonmodified polycrystalline iron fiber showed less reflection loss under same conditions.