新型易溃散改性水玻璃砂的研究

介绍了水玻璃工艺研究取得的最新进展，研制的新型改性水玻璃是一种无机和有机相复合的铸造粘剂，具有常温强度高，残留强度低，抗吸湿性好等优点，生产实际表明，采用新型改性水玻璃粘结剂的酯硬化工艺，可使水玻璃的加入量降为2．5％－3．0％，水玻璃砂的溃散性显著改善。     

高质量低成本改性水玻璃粘结剂及其应用

本文介绍了一种高质量、低成本的改性水玻璃粘结剂的性能及其应用情况,它既可用于酯硬化自硬水玻璃砂工艺、也可用于CO2硬化水玻璃砂工艺.生产实践表明,该新型改性水玻璃采用酯硬化水玻璃砂工艺时的水玻璃加入量为1.8%～2.8%,采用CO2硬化水玻璃砂工艺时水玻璃加入量为3.5%～4.5%,而销售价格仅为目前其它商品改性水玻璃的2/3左右,为新一代改性水玻璃砂工艺的推广应用展示了广阔的前景.     

酯硬化改性水玻璃砂在铸钢件上的应用

酯硬化改性水玻璃砂是生产铸钢件较理想的造型材料，它具有强度高，残留强度低，硬化速度快等优点，我厂铸钢件生产实践表明，采用新开发的酯硬化改性水玻璃砂工艺，可使水玻璃加入量降到3％以下，溃散性明显改善，而且旧砂回用率达70％以上。     

改性水玻璃的红外光谱分析

用改性树脂对水玻璃进行改性,为了解改性后水玻璃的分子结构会产生什么变化,硬化前、后普通和改性水玻璃有什么区别,从而对改性水玻璃的改性机理和硬化机理进行研究,对硬化前、后的普通水玻璃和改性水玻璃进行红外光谱(IR)分析.红外光谱分析表明:改性水玻璃的分子结构中都或多或少地含有改性树脂的极性基团.改性树脂的加入使红外吸收光谱中氢键的吸收峰增强,证实改性树脂中的极性化合物借氢键吸附在水玻璃凝胶胶粒的表面,形成高分子保护层.限制凝胶胶粒的长大,从而获得细小的水玻璃凝胶肢粒,达到提高粘结强度的目的.红外光谱分析还证实:无论是改性水玻璃,还是普通水玻璃,吹CO2硬化时的硬化机理均包括物理脱水和化学反应两部分.     

水玻璃磁化改性对水玻璃砂性能的影响

水玻璃磁化改性对水玻璃砂性能的影响研究结果表明，磁化改性水玻璃砂可延长可使用时间２５％左右。由于提高了水玻璃粘结强度，使水玻璃加入量降到２．５％左右，并改善了水玻璃砂溃散性。指出磁化改性效果会在２４小时后消失。发现水玻璃输导管材料对磁化改性效果有影响。     

开发高质量水玻璃砂硬化用有机酯的原理和方向

水玻璃砂用有机酯硬化时，应“适度反应、强力脱水”。反应率不宜使水玻璃的模数〉4，但反应也是促进脱水的动力，不能过低，所以要适度。水玻璃在硬化过程中的脱水可划分为反应脱水、化学物理脱水和挥发脱水三个阶段。反应脱水约3％，化学物理脱水和挥发脱水的任务约35％。余水达到20％左右即可进行浇注。若〈20％即认为硬透性好。因此化学物理脱水率／反应率的比值对有机酯的硬化速度、硬透性和硬化强度有决定性影响。列举了有机酯的化学结构和物理-化学性质，以及无盐水玻璃对上述比值的影响。     

新型酯硬化水玻璃砂的优点及影响其性能的因素

水玻璃砂的常温强度越高，其溃散性通常越差。在保证水玻璃砂具有足够的常温强度的条件下，获得好的溃散性一直是铸造工作者追求的目标。笔者介绍了新型酯硬化水玻璃砂的性能特点，就酯硬化改性水玻璃砂常温强度和溃散性的影响因素与改进方法进行了试验研究和探讨。     

典型方法和材料对水玻璃的改性效果与机制

研究比较了超声处理、纳米粉末改性、复合材料改性等水玻璃粘结剂改性方法及材料对水玻璃粘结剂的改性效果;分析了水玻璃的改性机制。试验结果表明,超声处理虽然提高了水玻璃砂的常温强度,却也恶化了溃散性;水玻璃经过纳米氧化物粉末改性后,适量纳米氧化物粉末可以在一定程度上改善水玻璃砂的溃散性,但常温强度却不能得到较大幅度的提高,作者开发的复合改性剂,既可提高水玻璃砂的常温强度,又可改善水玻璃砂的溃散性。借助XPS和SEM微观分析的方法,探讨了水玻璃粘结剂改性方法及材料对水玻璃粘结剂的改性机理。     

CO2硬化法用水玻璃粘合剂改性的研究

提高CO2水玻璃砂粘结强度的关键在于抑制硬化过程中胶粒的过度长大，可行的途径是向水玻璃中引入能与水玻璃起作用并能阻抑胶粒长大，而且对CO2硬化不引起、或少引起负面影响的物质。选择了含有—COONa极性基的有机合成物为1^#改性树脂；含有HO CH2OH极性基的有机合成物为2^#改性树脂，含有一CONH2极性基的有机物为3^#改性树脂，作为改性剂的主干材料对水玻璃进行改性处理。试验结果表明，改性水玻璃尤其是1^#改性树脂改性水玻璃18^#与普通水玻璃相比，明显提高常温下的粘结强度；显著改善热强度和高温强度；消除了800℃时的残留强度峰值。     

复合硬化剂——钠水玻璃自硬砂试验研究

在分析了钠水强度砂各种硬化方法的基础上，认为尽可能抑制化学硬化，加强物理硬化，则有利于自硬砂强度的提高。为此研究出了由有机酯ＭＤＴ－９０１与ＢＳ干燥剂组成的新型复合硬化剂。在钠水玻璃用量为３％时，加入复合硬化剂０．３％可以提高固化速度获得较高强度通过研究还指出了不同模数及比重的钠水玻璃可以有效地调节固化速度及强度，应用此复合硬化剂还可降低成本，降低砂芯吸湿性，改善溃散性，应用于生产集装箱箱角件效果     

改性水玻璃的生产与应用

介绍了水玻璃的老化现象以及阻止老化的方法，同时提出了改性水玻璃生产的工艺原理，产品在现场应用中取得了比较好的效果。改性水玻璃无论从产品的生产工艺，还是使用性能，特别是环保角度考虑，具有较好的推广价值。     

改性水玻璃在有机酯自硬砂中的应用

介绍了改性水玻璃在有机酯自硬砂中的应用，生产实践证明，有机酯自硬砂中改性水玻璃相比普通水玻璃来说，具有加入量低，强度高，溃散性好，有利于旧砂的再生回用等优点。     

Recent advances in waterglass sand technologies

This paper reports some new understandings and advances in waterglass sand technologies. The multiple chemical modification process can increase the binding strength of the waterglass sand by up to 50%-70%. Therefore, the additions of the modified waterglass can be decreased to 3.0%-4.0% for CO2 process and to 2.0%-2. 5% for organic ester hardening process, and greatly improve the collapsibility and reclaimability of the sand. Based on the new understandings and experimental results reported in this paper, several original ideas, such as nano modification, have been proposed to promote advances of waterglass sand technologies,     

对水玻璃和水玻璃砂性状参数的新认识

过去认为决定水玻璃性状的参数仅模数和浓度二项,它被写入了国家标准中。随着水玻璃砂的应用迅速扩大,出现了许多新问题。原来除此之外,水玻璃中掺杂的可溶性盐类(胶料的ζ位)、金属离子半径的大小(决定老化行为和其他许多水玻璃的使用性质)、硅溶胶向硅凝胶转换的许多控制因素,都显著影响水玻璃和水玻璃砂的工作性状。水玻璃的纳米改性和定向凝胶化技术也初露睨端。     

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。     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.     

The First Phase of the SRIF Industrialized Base in ＂West Area＂ Has Been Put into Operation

After nearly two years＇ tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry （SRIF）, located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation.     

Thermodynamics Study on the Decomposition of Chromite with KOH

Institute of Process Engineering, Chinese Academy of Sciences, China, has proposed a method for oxidative leaching of chromite with potassium hydroxide. Understanding the mechanism of chromite decomposition, especially in the potassium hydroxide fusion, is important for the optimization of the operating parameters of the oxidative leaching process. A traditional thermodynamic method is proposed and the thermal decomposition and the reaction decomposition during the oxidative leaching of chromite with KOH and oxygen is discussed, which suggests that chromite is mainly destroyed by reactions with KOH and oxygen. Meanwhile, equilibrium of the main reactions of the above process was calculated at different temperatures and oxygen partial pressures. The stable zones of productions, namely, K2CrO4 and Fe2O3, increase with the decrease of temperature, which indicates that higher temperature is not beneficial to thermodynamic reactions. In addition, a comparison of the general alkali methods is carried out, and it is concluded that the KOH leaching process is thermodynamically superior to the conventional chromate production process.     

Influence of Heat Treatment on Damping Behaviour of the Magnesium Wrought Alloy AZ61

The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to the evolution of precipitation process. The influence of precipitation on damping behaviour was explained in the framework of the dislocation string model of Granato and Lücke.