热压烧结法制备碳酸钠水溶性型芯研究
发布时间：2018-10-30 16:20
【摘要】：国内汽车工业的飞速发展以及汽车轻量化的结构趋势,使得铝合金铸件的应用需求大幅上升。在具有复杂内腔或弯曲管道结构的铝合金铸件生产中,遇水即可溃散、污染小能耗低的水溶芯技术拥有广泛的应用前景。目前水溶芯的局限主要在于其强度相对偏低、抗吸湿性能差、对设备要求高等方面。本文以水溶性砂芯为研究对象,在归纳了目前水溶性砂芯各种制芯工艺的优缺点后,在热压法和压制烧结的基础上提出了热压烧结法制芯。以十水碳酸钠为粘结剂、硅砂为基体材料,研究了热压工艺中的配方工艺和成型工艺、烧结工艺对型芯的强度、水溶溃散性能的影响。本文的主要内容如下:(1)研究了热压烧结工艺中十水碳酸钠加入量、膨润土加入量、加热温度、加热时间、烧结温度、烧结时间对型芯抗拉强度的影响规律。研究结果表明,型芯的强度随参数的变化均为先增大后减小的趋势。当十水碳酸钠加入量为40%wt、膨润土加入量为7%wt、加热温度为150℃、加热时间为10min时,得到的型芯热压初始抗拉强度最高,为1.1MPa;当烧结温度为850℃、烧结时间为30min时,得到的型芯烧结强度最高,为6.4MPa。(2)分析了热压工艺的粘结机理。使用热重分析法研究了加热时间、加热温度对型芯含水量及型芯强度的影响,合理的加热制度使无机盐桥充分结晶析出的同时,令膨润土保留微量的水分从而提供型芯增强效果。使用电镜扫描分析形貌结合型芯强度,分析了十水碳酸钠加入量、膨润土加入量对无机盐在砂粒表面结晶形态的影响。(3)分析了烧结工艺的强化机理。烧结反应可随时间分为三个阶段:第一阶段,型芯由于脱水而低于初始强度;第二阶段,型芯的粘结力由碳酸钠在砂粒表面的附着力转变为碳酸钠的内聚力,型芯此时获得较高的烧结强度;第三阶段,碳酸钠基本全部转换为新相,水溶性能大幅减少,此时粘结力主要由新相提供,型芯强度降低甚至弯曲变形无法使用。
[Abstract]:With the rapid development of domestic automobile industry and the structural trend of automobile lightweight, the application demand of aluminum alloy castings has increased greatly. In the production of aluminum alloy castings with complex inner cavity or curved pipe structure, water collapses can be caused by water, and the water-soluble core technology with low pollution and low energy consumption has a wide application prospect. At present, the limitation of water-soluble core is that its strength is relatively low, its moisture absorption performance is poor, and the requirement of equipment is high. In this paper, the water-soluble sand core is taken as the research object. After summarizing the advantages and disadvantages of the current water-soluble sand core making process, the hot pressing sintering method and pressing sintering method are proposed. Using sodium carbonate decahydrate as binder and silica sand as matrix material, the formula and forming process of hot pressing process and the influence of sintering process on strength and water-soluble collapsibility of mould core were studied. The main contents of this paper are as follows: (1) the effects of sodium carbonate decahydrate, bentonite addition, heating temperature, sintering time, sintering temperature and sintering time on the tensile strength of the core were studied. The results show that the strength of the core increases first and then decreases. When the amount of sodium carbonate decahydrate is 40 wt, bentonite is 7 wts, heating temperature is 150 鈩，
本文编号：2300511
[Abstract]:With the rapid development of domestic automobile industry and the structural trend of automobile lightweight, the application demand of aluminum alloy castings has increased greatly. In the production of aluminum alloy castings with complex inner cavity or curved pipe structure, water collapses can be caused by water, and the water-soluble core technology with low pollution and low energy consumption has a wide application prospect. At present, the limitation of water-soluble core is that its strength is relatively low, its moisture absorption performance is poor, and the requirement of equipment is high. In this paper, the water-soluble sand core is taken as the research object. After summarizing the advantages and disadvantages of the current water-soluble sand core making process, the hot pressing sintering method and pressing sintering method are proposed. Using sodium carbonate decahydrate as binder and silica sand as matrix material, the formula and forming process of hot pressing process and the influence of sintering process on strength and water-soluble collapsibility of mould core were studied. The main contents of this paper are as follows: (1) the effects of sodium carbonate decahydrate, bentonite addition, heating temperature, sintering time, sintering temperature and sintering time on the tensile strength of the core were studied. The results show that the strength of the core increases first and then decreases. When the amount of sodium carbonate decahydrate is 40 wt, bentonite is 7 wts, heating temperature is 150 鈩，
本文编号：2300511
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