铸造用CO2硬化冷芯盒材料及工艺的发展

铸造用CO2硬化粘结剂系统具有气硬冷芯盒的优点,同时又具有环保方面的优势。主要介绍了水玻璃-CO2法、聚丙烯酸钠-CO2法、酚醛树脂-CO2法三种工艺。这些工艺方法近年来国内外研究较多,并且取得了很大进展。     

Zirconium-Embedded Polyhedral Oligomeric Silsesquioxane Containing Phosphaphenanthrene-Substituent Group Used as Flame Retardants for Epoxy Resin Composites

A zirconium hybrid polyhedral oligomeric silsesquioxane derivative (Zr–POSS–bisDOPO) is synthesized by the corner-capping and Kabachnik–Fields reactions. It is characterized by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance spectroscopy (NMR), and then used as a flame retardant in diglycidyl ether of bisphenol A (DGEBA) to endow epoxy resin (EP) with flame retardancy. The flame retardancy, thermal stability, and mechanical properties of the cured EP/Zr–POSS–bisDOPO composites are investigated. The results show that when Zr–POSS–bisDOPO is added by 5–7 wt%, the EP/Zr–POSS–bisDOPO composites pass the UL-94 V-0 rating test. In addition, they have a better flame-retardant effect than pure EP. The combination of Zr atom embedded in the Si O cubic cage and the two phosphaphenanthrene substituent groups in one corner of cubic cage is expected to realize the Zr/Si/P ternary intramolecular hybrid synergistic effect and achieve the possibility of dispersing metal–POSS cages at a sub-micrometer-scale level into polymer matrix. It also proves that Zr–POSS–bisDOPO produces phosphorus-containing free radicals and terminates the chain reactions in gas phase. Meanwhile the Si O Si and Zr O units are retained in the solid phase, which promote the char formation and enhance the flame retardancy. This kind of Zr-doped POSS will be helpful for developing the new metal–POSS hybrid flame-retardant and polymer composites.     

Effect of Bio-Based Cobalt Alginate on the Fire Safety and Mechanical Properties for Epoxy Resin

There is a growing demand to develop epoxy resins (EP) with smoke suppression as well as satisfactory flame retardancy. Herein, bio-based cobalt alginate is successfully fabricated and incorporated into EP to prepare EP/Cobalt Alginate composites with better fire safety performance. The addition of cobalt alginate reduces the thermal-decomposition rate, temperature at maximum weight-loss rate of EP, whereas obviously improves the thermal stabilities at a higher temperature range. Furthermore, the addition of cobalt alginate substantially reduces the fire hazard of EP, resulting in 56.2% reduction in peak heat release rate, as well as 17.8% and 56.3% reduction in total smoke production and peak smoke production rate, respectively, compared with EP matrix. Moreover, the presence of cobalt alginate increases smoke-suppressant properties, according to the smoke density test. Additionally, the incorporation of cobalt alginate has no obviously destructive effect on the mechanical properties of EP, while EP/Cobalt Alginate-3 exhibits a 27.0% improvement in impact strength. In prospective, this study may provide a significant method for producing eco-friendly flame retardant EP.     

工业烟气设备的防腐蚀浅析

详细阐述了工业烟气设备装置中的烟道、烟囱、洗涤塔等的腐蚀原理，并针对不同场合的情况分别讨论防腐蚀材料的选择及其结构形式，为工业烟气设备的防腐蚀提供可靠的处理方法。     

铸造用聚氨酯粘合剂组份Ⅰ酚醛树脂合成研究

铸造用的聚氨酯粘合剂组合物，主要由极性和非极性溶剂溶解的酚醛树脂组份I和非极性溶剂稀释的聚异氰酸酯组份Ⅱ组成。组份Ⅰ酚醛树脂结构、性能是决定该类粘合剂性能因素之一。本文对铸造用聚氨酯粘合剂的组份Ⅰ酚醛树脂结构、合成方法、原料材料选择等问题进行了分析讨论，为铸造用聚氨酯粘合剂的组份Ⅰ的制备和苯醚型酚醛树脂的合成提供一些参考。     

Friction and wear properties of pitch／resin densified carbon—carbon composites used for airbrakes

By use of X-ray diffractometry and scanning electron microscope(SEM),the friction and wear results obtained from MM-1000 dynamometer tests of CVI pitch/resin C/C composites were analyzed.By investigating the factors that affected the friction and wear properties,such as matrix carbon,applcation environment,graphitization degree and brake pressure,etc,friction and wear mechanism of carbon materials were probed.The results indicate that pitch densified CVI initially treated composite is more graphitizable with its graphitization degree up 59 62%,and which results in uniform small debris easier to generate,more smooth friction curves with the coefficient of 0.3-0.4 and relatively higher wear and mass loss,compared with CVI/resin C/C composites.It was further proved by SEM observation that tribological behavior of C/C composite was system dependent.Factors determining the friction and wear properties such as the size of debris and its influence on friction and wear,brake pressure,graphization degree and debris bilm formation interacted and affected each other.The friction and wear mechanism of C/C composites under different high temperature treatments needs further research.     

CO2固化碱性酚醛树脂的制备及固化机理研究

铸造用CO2固化碱性酚醛树脂是一种新型造型、制芯用粘结剂,它是由羟甲基含量较高的甲阶碱性酚醛树脂和含氧酸盐及碱等物质组成的混合物,甲阶碱性酚醛树脂性能及它们的组成是影响CO2固化碱性酚醛树脂砂强度的主要因素。模仿实际CO2固化酚醛树脂砂的固化过程,利用测定不同条件下碱性酚醛树脂水溶液pH值变化的方法,对CO2固化碱性酚醛树脂与不同交联剂的固化机理进行了探讨,从中得出有关CO2固化碱性酚醛树脂的交联剂和碱的用量范围,并在此基础上,考察它们和表面稳定剂对砂型抗压强度的影响,获得铸造用CO2固化碱性酚醛树脂较佳组成。     

呋喃树脂砂型球铁铸件异常组织分析

采用呋喃树脂砂型铸造球铁件时，由于树脂和硬化剂分解产生的C,S渗入铁液使铸件表层局部区域形成大量密集的细片状和点状过冷石墨，这些区域加工表面上呈灰暗色。在容易产生这种缺陷的部位设置冷铁．使该部位不与树脂砂接触，因而能避免上述缺陷产生。     

杭州湾跨海大桥钢管桩的涂层防护

杭州湾跨海大桥采用钢管桩沉桩基础。钢管桩的腐蚀问题采用涂层加阴极保护的防护体系,其中涂层部分采用单层/双层/三层重防腐环氧粉末喷涂防护方案解决。介绍了三种涂层结构及其用途。     

多元酚——甲醛树脂中游离酚,游离醛含量的测定

多元酚－－甲醛树脂是本院开发的热固粘接剂新产品，本文给出了这一产品技术指标中游离酚、游离醛含量的测定方法，并对方法进行了讨论。