铸造用水玻璃改性技术及应用研究

【作者】 谈剑；

【导师】 张希俊；

【作者基本信息】 昆明理工大学 ， 材料加工工程， 2007， 硕士

【摘要】 在占铸造份额90%的三大型砂当中,水玻璃砂在降低生产成本,提高铸件质量,简化工艺操作,特别是环境保护等方面都具有很大优势,是最有可能实现绿色清洁铸造,符合二十一世纪生产要求的型砂。但这种砂也存在吸湿性强、溃散性差,水玻璃加入量大而导致落砂清理困难,旧砂回用性差的问题,给水玻璃砂的使用和推广带来很大麻烦。为此,开发适用于铸造生产的具有高粘结性能和高抗吸湿性的改性水玻璃,以降低型砂的水玻璃加入量,是一个实用而迫在眉睫的问题,也是本课题研究目标的所在。本文对水玻璃特性、改性方法及改性机理进行了全面的总结与分析。以“水玻璃的物理改性在于消除老化;化学改性在于阻缓老化”的改性指导思想为基础,得出了物理改性主要是往水玻璃体系中供应能量,打散因老化而聚合的胶粒,使聚硅酸的聚合度重新均匀化,从而消除水玻璃的老化;化学改性主要是向水玻璃体系中引入新物质,以吸附或穿插在聚硅酸表面,降低表面能,提高稳定性,减小聚硅酸进一步缩聚的倾向,从而阻缓水玻璃老化的改性方法。在水玻璃改性机理分析指导下,确定了水玻璃改性方案。物理方面采用脉冲电流对水玻璃进行改性。设计制作了一套脉冲电流触发装置,以不同的电压、频率、电极及脉冲处理时间分别对水玻璃进行改性处理,然后对其粘结性能进行了试验研究,并用正交实验法优选了脉冲电流改性水玻璃的最佳工艺参数。化学方面采用多重化学复合对水玻璃进行改性。研究分别从有机物、无机盐、表面活性剂、纳米粒子四个方面进行,通过对改性剂所要起到作用的分析与选择范围的探索,选取了四种有机物及三种其它物质作为多重化学复合的改性材料,分别研究了它们的加入量与水玻璃性能的关系,确定了较佳改性配比。为了进一步提高水玻璃的综合改性效果,本文提出了物理-化学联合改性水玻璃的设想,进行了联合改性工艺的研究,并采用有机酯硬化和CO₂,硬化工艺对联合改性水玻璃的粘结强度及多种使用性能进行了测试。实验结果表明:各种改性都能使水玻璃的抗吸湿性和粘结强度有不同程度的提高,残留强度降低。联合改性水玻璃适用于CO₂和有机酯硬化工艺,具有良好的使用性能。在温度23℃,湿度60%RH的环境下,联合改性能提高CO₂硬化水玻璃砂的抗吸湿性能166.7%,有机酯硬化水玻璃砂的抗吸湿性能41.7%;在温度25℃,湿度20%RH的环境下,能使它们的粘结强度分别提高78.3%和58.2%,残留强度降低63.7%和60.0%。联合改性有效地提高了水玻璃的抗吸湿性与粘结性,可以在保证型砂使用强度的前提下将有机酯硬化水玻璃砂的水玻璃绝对加入量降低到2.33%,CO₂硬化水玻璃砂的水玻璃绝对加入量降低到3.89%,残留强度下降2/3。最后,用透射电子显微镜,红外光谱仪,扫描电子显微镜等设备对用不同方法改性的水玻璃进行了观察与分析。检测结果进一步验证了作者对各种改性机理分析的正确性。更多还原

【Abstract】 In occupies of the casting share 90% three big molding sands, the sodium silicate granulated substance is reducing the production cost, improves the casting quality, the simplification craft operation, specially aspects and so on environmental protection all have the very big superiority, is most has the possibility to realize the green clean casting, conforms to the 21st century production request molding sand. But this kind of granulated substance also has the water absorbability strongly, is defeated and dispersed the difference, the sodium silicate joins the quantity to cause the sand-out cleaning up difficulty greatly, the old granulated substance sales commission difference question, brings for the sodium silicate granulated substance use and the promotion is very greatly troublesome. Therefore, the development is suitable in the casting production has the high bonding properties and the high anti-water absorbant modified sodium silicate, reduces the molding sand the sodium silicate to join the quantity, is one practical and the imminent question, also is this topic research aim.This article added sodium silicate characteristic, the modified method and the modified mechanism has carried on the comprehensive summary and the analysis. Lies in the elimination take the sodium silicate physical modification to get older, chemistry modification lies in anti-slow aged the guiding ideology as a foundation, has obtained the physical modification mainly is supplies the energy toward the sodium silicate system in, scatters because of the colloidal particle which gets older gets together, causes to gather the silicic acid polymerization degree to uniformize, thus elimination sodium silicate aging; Chemistry modification mainly is introduces the new material to the sodium silicate system in, adsorbs or the’ alternation is gathering the silicic acid surface, reduces the surface energy, enhances the stability, reduces gathers the silicic acid further condensation tendency, thus the anti- slow sodium silicate gets older modified method.Under the sodium silicate modified mechanism analysis instruction, has determined the sodium silicate modified plan. The physical aspect uses the pulse electric current adding water glass to carry on the modification. The design has manufactured a set of pulse electric current trigger, by the different voltage, the frequency, the electrode and the pulse process time adds water the glass to carry on modified processing separately, then has conducted the experimental study to its bonding properties, and used the orthogonal cut-and-try method optimal pulse electric current modified sodium silicate the best craft parameter. Chemistry aspect uses the multiple chemistry compound adding water glass to carry on the modification.The research from the organic matter, the inorganic salt, the surface active agent, the nanometer granule four aspects carries on separately, through wants the function analysis and the choice scope exploration to the modifier, has selected four organic matters and three other materials took the multiple chemistry compound modified material, studied them to join the quantity and the sodium silicate performance relations separately, has determined the good modified allocated proportion.In order to further enhance the sodium silicate the comprehensive modified effect, this article proposed the physical - chemistry union modified sodium silicate tentative plan, has conducted the union modified craft research, and used the organic ester hardening and the CO₂ hardening craft has carried on the test to the union modified sodium silicate caking intensity and many-kinds of operational performance.The experimental result indicated that, each kind of modification all can cause the sodium silicate the anti-water absorbability and the caking intensity has the varying degree enhancement, the residual intensity reduces.The union modified sodium silicate is suitable for CO₂ and the organic ester hardening craft, has the good operational performance. In the temperature 23℃, under the humidity 60%RH environment, changes the performance to enhance the CO₂ hardening sodium silicate granulated substance jointly the anti-moisture absorption performance 166.7%, organic ester hardening sodium silicate granulated substance anti-moisture absorption performance 41.7%; In the temperature 25℃, under the humidity 20%RH environment, can make their caking intensity to enhance 78. 3% separately and 58. 2%, the residual intensity reduces 63.7% and 60.0%. The union modification enhanced the sodium silicate anti-water absorbability and cohesiveness effectively, may join in under the guarantee molding sand use intensity premise the organic ester hardening sodium silicate granulated substance sodium silicate the quantity to reduce absolutely joins to the 2.33%, CO₂ hardening sodium silicate granulated substance sodium silicate the quantity to reduce absolutely 3.89%, the residual intensity drops 2/3.Finally, with the transmission electron microscope, the infrared spectroscope, equipment and so on scanning electron microscope to used the different method modified sodium silicate to carry on the observation and the analysis. The examination result has further confirmed the author the accuracy which analyzes to each kind of modified mechanism.更多还原