Ni基高温合金精密铸造型壳的制备及其性能

发布时间：2018-02-23 05:39

  本文关键词： 陶瓷型壳 强度 挠度 透气性 界面稳定性　出处：《沈阳理工大学》2016年硕士论文　论文类型：学位论文

【摘要】：高温合金铸件质量与所使用的陶瓷型壳性能密切相关。本文主要研究了陶瓷原料与型壳性能的关系。陶瓷原料主要涉及了高岭土和刚玉两种耐火原料和两种硅溶胶粘结剂。型壳性能涉及强度、挠度、透气性和界面稳定性共四个方面。研究了不同条件下的型壳性能变化趋势和陶瓷原料的物相组成随温度的演化规律、形成机理,探讨了建立物相组成与型壳性能的关系,从而掌握影响型壳强度、挠度、透气性、界面稳定性的影响因素和变化规律。型壳试样所使用的关键材料有:FSIII快干型硅溶胶(简称F硅溶胶)和GS30普通硅溶胶(简称G硅溶胶)两种粘结剂和EC95粉、硅酸锆粉、刚玉砂、煤系(1#)和非煤系(2#)高岭土五种耐火材料。利用XRD、DTA分析了高岭土的物相组成;利用三点弯曲法和高温自重变形法测定了型壳的抗折强度和挠度,通过XRD和SEM等方法研究了型壳的物相组成和显微结构;利用高温透气性设备对精铸型壳在不同温度下的透气性进行了分析;实验还研究了多种耐火材料粉末及型壳面层与高温合金的界面反应情况。(1)高岭土原料中出现了方石英、莫来石、石英相和石英玻璃相,但是在两种高岭土中的含量不尽相同。与常温强度相比,两种高岭土型壳的高温强度均有显著提高。在高温下,型壳内出现了石英玻璃的晶化转变、方石英转变以及莫来石化反应,但不同型壳体系的相变规律不同。FSIII和GS30两种硅溶胶对型壳强度的影响不大。这是因为,与原料中的方石英相比,石英玻璃对莫来石的形成有促进作用,进而提高型壳的高温强度而减小溃散强度。(2)高岭土型壳在1500℃及以上的温度下高温蠕变急剧增加,而EC95型壳在1000-1600℃的温度范围内变形量上升较为平缓;烧结后高岭土型壳会向背层方向而非沿重力方向弯曲直至断裂。有机物提高了高岭土型壳的蠕变变形,但对EC95型壳的影响不明显。这是因为高岭土型壳与重力相反的蠕变变形由刚玉层与高岭土层的热膨胀不匹配导致,且石英玻璃含量越多则高岭土层的膨胀量越大。EC95型壳的变形是由于型壳中石英玻璃的粘性流动所致。(3)在1000-1400℃时,高温透气性随温度升高而稳定上升,但耐火材料对型壳透气性的影响不大;在1400℃以上的温度时,高岭土型壳的透气性显著升高;随着试验温度的升高,EC95型壳的透气性上升速率先快后慢。无定形二氧化硅可以转变为方石英或与EC95粉反应生成莫来石。(4)氧化钇、铝酸钴和刚玉粉末与417G合金界面反应严重。碳化硅和煤系高岭土不适用于配置型壳面层浆料。EC95粉与硅酸锆均与合金发生轻微的界面反应,合金与EC95面层反应容易产生机械粘砂,而与硅酸锆面层的反应则表现为化学粘砂。
[Abstract]:The quality of superalloy castings is closely related to the properties of ceramic shell used. The relationship between ceramic raw materials and shell properties is studied in this paper. The ceramic raw materials mainly involve two kinds of refractory materials, kaolin and corundum, and two kinds of silicon solution. Adhesives. Properties of moulded shells, relating to strength, Four aspects, deflection, permeability and interfacial stability, are studied in this paper. The changing trend of shell properties under different conditions, the evolution law of phase composition of ceramic raw materials with temperature, the formation mechanism, and the relationship between the phase composition of the molded shell and the properties of the shell are discussed. In order to master the impact of the shell strength, deflection, air permeability, The key materials used in the mold shell samples include two kinds of binders: FSIII fast dry silica sol (F silica sol) and GS30 common silica sol (G silica sol) and EC95 powder, zirconium silicate powder, corundum sand, etc. The phase composition of kaolin was analyzed by XRDX DTA, and the flexural strength and deflection of the shell were measured by three point bending method and high temperature autogravity deformation method. The phase composition and microstructure of the mold shell were studied by XRD and SEM, and the permeability of the die casting shell at different temperatures was analyzed by means of high temperature gas permeability equipment. The interfacial reaction between the powder and shell layer of various refractories and superalloy was also studied. (1) the raw materials of kaolin, such as cristobalite, mullite, quartz and quartz glass phase, were found in the raw materials of kaolinite, such as quartz, mullite, quartz and glass. However, the content of kaolin in the two kinds of kaolin is different. Compared with the normal temperature strength, the high temperature strength of the two kinds of kaolinite molded shell is obviously improved. At high temperature, the quartz glass crystallizes in the mold shell. The change of cristobalite and mullite reaction, but the phase transition law of different shell system is different. FSIII and GS30 silica sol have little effect on the strength of molded shell, this is because compared with the cristobalite in raw material, Quartz glass can promote the formation of mullite, thus increasing the high temperature strength of the shell and decreasing the collapsing strength.) the high temperature creep of the kaolinite shell increases sharply at 1500 鈩，

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