热作用对环保型黄壤土砂性能的影响研究

发布时间：2018-05-05 14:10

本文选题：环保砂 + 绿色铸造　；参考：《东华大学》2017年硕士论文

【摘要】：砂型铸造是铸造工艺的主要方法,其中湿型砂适用范围最广,耗用量最大。国内外广泛使用的煤粉湿型砂废砂排放量大,污染环境严重;铸造生产中产生的有毒、有害气体既污染环境又影响工人健康。因此,实现砂型铸造的绿色清洁生产对实现“绿色铸造”具有极其重要的意义。东华大学与企业合作,研究开发了一种环保型黄壤土砂,该环保砂颜色呈土黄色,全由无机材料组成。使用这种型砂进行铸造生产,车间干净,不会排放有害气体危害工人健康,且旧砂不会污染环境。环保砂的常温湿压强度高,可用做型(芯)砂材料。本文主要介绍作者对环保砂的铸造回用性能和热物理性能进行研究。首先,研究了热作用对环保型黄壤土砂铸造性能的影响。测试研究环保砂和煤粉砂在不同温度下多次烧损后湿压强度和透气性的变化,使用热分析仪对环保型砂进行差热分析及热重分析,使用热台偏光显微镜观察型砂在升温过程中形态变化。通过分析其DSC-TG曲线及高温形态变化,解释型砂在不同温度烧损后湿压强度和透气性的变化。研究结果表明,随烧损温度上升,环保砂强度下降趋势比煤粉砂缓和的多,适应温度范围更宽,耐烧损能力更强,环保砂回用性更好。其次,通过向环保型黄壤土砂添加少量添加剂,探究环保砂的抗压强度、残留强度、高温热压强度以及存放稳定性的变化,以期得到性能更加完善的环保砂。研究结果表明,环保砂加入适量添加剂能大幅提升型砂的抗压强度和高温热压强度,残留强度虽有一定提升但仍在合理范围内,溃散性很好;热膨胀性能降低,能有效防止铸件变形,同时良好的存放稳定性能够使环保砂在造型之前保持良好的性能。然后,对环保型黄壤土砂的热导率、比热容、导温系数、和高温热膨胀性等热物理性能进行系统的测试研究,并和传统煤粉湿型砂进行对比,进一步认识环保砂的热物性特点。之后对环保砂添加HB粘结剂,研究HB粘结剂含量对环保砂热物性的影响。研究结果表明,环保砂的热导率、比热容高于煤粉砂,导温系数略低于煤粉砂,高温热膨胀性能基本一致。适量HB粘结剂的加入可有效降低环保砂的热导率、热膨胀率,同时提高其比热容和导温系数。环保砂这些优异的热物理性能使铸件在铸型中冷却凝固时能更好的保证质量。最后,为了验证环保型黄壤土砂用做型(芯)砂材料对铸件质量和铸造缺陷的影响,对环保砂进行了浇注验证并与煤粉砂进行了对比,从铸件的粘砂和表面粗糙度两个方面来考察环保型黄壤土砂的适用性。实验结果表明:环保型黄壤土砂铸件表面能形成易剥离的烧结壳,轻敲即可脱落,铸件表面光洁、细腻,铸件质量好。研究工作对深入了解环保型黄壤土砂的循环使用性能,控制生产铸件成本,推行绿色环保铸造生产工艺,具有基础性的指导作用。
[Abstract]:Sand mold casting is the main method of casting technology, in which wet sand is the most widely used and the consumption is the largest. The waste sand of pulverized coal powder is widely used at home and abroad, which pollutes the environment seriously, and the poisonous and harmful gases produced in foundry not only pollute the environment but also affect the health of workers. Therefore, it is very important to realize green cleaner production of sand mold casting. A kind of environmental friendly yellow loam sand has been developed by Donghua University in collaboration with enterprises. The environmental friendly sand is khaki-colored and composed of inorganic materials. The molding sand is used for foundry production, the workshop is clean, the harmful gas will not be emitted and the old sand will not pollute the environment. Environmental-friendly sand has high wet compression strength at room temperature and can be used as core sand material. This paper mainly introduces the author's research on the foundry reusability and thermophysical properties of environmentally friendly sand. Firstly, the effect of thermal action on casting properties of environmental friendly yellow loam sand was studied. The changes of wet compression strength and permeability of environmental friendly sand and pulverized coal sand after repeated burning at different temperatures were studied. The differential thermal analysis and thermogravimetric analysis of environmental friendly sand were carried out by using thermal analyzer. The morphologic changes of molding sand during heating process were observed by means of hot platform polarizing microscope. By analyzing the DSC-TG curve and the change of high temperature morphology, the changes of wet compression strength and permeability of molding sand after burning at different temperatures were explained. The results show that with the increase of burning temperature, the intensity of environmental friendly sand decreases much more than that of pulverized coal sand, and the temperature range is wider, the ability of resistance to burning damage is stronger, and the recycling ability of environmental friendly sand is better than that of pulverized coal sand. Secondly, by adding a small amount of additives to the environmental friendly yellow loam sand, the changes of compressive strength, residual strength, high temperature hot pressing strength and storage stability of the environmental friendly sand were investigated, in order to obtain more perfect environmental friendly sand. The results show that the compressive strength and high temperature hot compression strength of molding sand can be greatly improved by adding appropriate additives to environmental friendly sand, and the residual strength is still within a reasonable range, the collapsibility is very good, and the thermal expansion property is reduced. Can effectively prevent casting deformation, and good storage stability can make environmental protection sand before molding to maintain good performance. Then, the thermal physical properties such as thermal conductivity, specific heat capacity, thermal conductivity coefficient and high temperature thermal expansion of environmental friendly yellow loam sand are systematically tested and studied, and compared with traditional coal powder wet molding sand, the characteristics of thermo-physical properties of environment-friendly sand are further understood. The effect of HB binder content on thermal properties of environmentally friendly sand was studied. The results show that the thermal conductivity, specific heat capacity and thermal conductivity of environmentally friendly sand are higher than those of pulverized coal sand, and the thermal conductivity coefficient is slightly lower than that of pulverized coal sand, and the thermal expansion performance at high temperature is basically the same. The addition of appropriate HB binder can effectively reduce the thermal conductivity, thermal expansion rate, and increase the specific heat capacity and thermal conductivity of environmentally friendly sand. Environmental friendly sand, such as excellent thermal physical properties, can better ensure the quality of castings during cooling and solidification. Finally, in order to verify the effect of environmental friendly yellow loam sand used as mold (core) sand material on casting quality and casting defects, the environmental protection sand was tested and compared with pulverized coal sand. The applicability of environmental friendly yellow loam sand was investigated from two aspects of sand and surface roughness of castings. The experimental results show that the surface of environmental friendly yellow loam sand castings can form easily peelable sintered shells, which can be shedded by tapping lightly. The casting surface is smooth and fine, and the quality of castings is good. The research work has the basic guiding function to understand the recycling performance of the environmental protection yellow loam sand, to control the production cost of the castings, and to carry out the green environmental protection casting production process.
【学位授予单位】：东华大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG221

【参考文献】