(SiC)p表面修饰及吸波性能研究

目的提高(SiC)P的吸波性能。方法采用低成本、环保型的化学镀镍方法对(SiC)P表面进行修饰,设计了氧化、亲水、敏化、活化系列增强前处理工艺,确定了(SiC)P表面修饰的最佳工艺流程。用SEM、EDS、XRD等分别表征了修饰前后(SiC)P形貌、成分、物相的改变,采用波导法测定了修饰后碳化硅复合粉体的介电性能,并以其为吸波剂在铝板上制备了吸波材料。结果修饰后,获得了镀层连续、无光滑(SiC)P裸露的较高质量的碳化硅复合粉体(简写为(Ni/SiC)P)。(Ni/SiC)P较原粉(SiC)P,其形貌、组成、结构发生了明显改变,且介电常数、介电损耗、吸波性能明显增强,其中,介电常数的实部增强约为22%,虚部增强约为20%。涂覆1层(Ni/SiC)P涂料,在17.12 GHz时,RL=−15.47 dB,大于涂敷2层原粉(SiC)P涂料的吸收效果。涂覆2层(Ni/SiC)P涂料,在16.11 GHz时,RL=−23.51 dB。结论采用低成本、环保型方法实现了(SiC)P表面高质量修饰,修饰后,复合颗粒(Ni/SiC)P的介电性能及吸波性能均明显提高。     

MPF玻璃布层压防火板制备工艺研究

为了得到性能优良的防火板,在弱碱条件下对三聚氰胺与苯酚、甲醛进行共缩聚得到三聚氰胺—苯酚—甲醛（MPF）树脂,并以其为基体树脂制备一系列层压板.结果表明,随着甲醛与苯酚摩尔比的提高,MPF树脂贮存期有一定延长,防火板材的甲醛释放量呈线性升高;防火板随着玻璃纤维层数的增加,其冲击强度、拉伸强度、弹性模量、洛氏硬度都有很大提高,但耐燃性有所下降.     

尖晶石型锡酸锌光催化降解二甲酚橙的性能

以SnCl4·5H2O和ZnSO4·7H2O为原料,用化学共沉淀法制备纳米尖晶石型锡酸锌光催化剂.通过X射线衍射分析(XRD)、光电子能谱分析(XPS)、扫描电镜(SEM)对催化剂进行表征.以波长λ=312 nm的光源对二甲酚橙水溶液光催化降解,讨论光催化剂用量、催化剂烧结温度、试液的pH值、光照时间等与二甲酚橙脱色率...     

An electron diffraction analysis of turbostratic graphite in cemented carbides

Electron diffraction patterns of nesting sequences of two-dimensionally crystallised polar-cap shaped turbostratic graphite often have fine spotty reflections lying in short streaks, whereas infinitely long reciprocal lattice rods (relrods) are expected for layered structures where every basal plane in the crystal is randomly rotated about the c-axis. In graphite the first order hk reflections of the relrods are 10 reflections. The short streaks are intense when polar caps have flattened poles because many streaks are then superimposed. Dark field microscopy shows that the short streaks image the flattened polar regions only and therefore these regions reflect only into the streaks. Models of the reciprocal lattice of layered structures combined with a model of partially crystallised graphite which has transformed from f.c.c. β-SiC, suggest that there is a relationship between the angles of rotation of basal planes, fixed by the stacking of {111} planes of a parent f.c.c. phase, and the thickness of platelets of perfect graphite forming in the process. Rotation of such platelets about the c-axis would still produce a turbostratic structure but because basal planes are now not all randomly rotated the lengths of the reciprocal lattice rods, which are inversely proportional to the thickness of platelets, would be correspondingly shorter. The shortness of the observed streaks is therefore an indication of the degree of crystallinity of the graphite.