铝、镁合金消失模铸造涂料的制备及其性能研究

发布时间：2018-02-21 20:19

本文关键词： 消失模铸造铝合金硅酸镁铝黄原胶流变性　出处：《中北大学》2017年硕士论文　论文类型：学位论文

【摘要】：消失模铸造是铝合金及镁合金铸造成型的一种重要方式,其中,铸造涂料对铸件质量起着至关重要的作用,特别是它能够很好地提高铸件表面光洁度和尺寸精度,降低铸件产生针孔、冷隔、粘砂、砂眼、积碳等缺陷出现的可能性。但是到目前为止,市场上还没有铝合金及镁合金专用的消失模铸造涂料,所以本文在于开发出综合性能优异的两种涂料。本文通过测试不同耐火骨料配比下的涂料性能,分别确定了适用于铝合金以及镁合金的耐火骨料,并且优化了涂料的耐火骨料配比;通过采用单因素实验,研究改变粘结剂以及悬浮剂的加入量后,涂料的性能变化,确定粘结剂和悬浮剂的较合适的加入量,特别有提到新型悬浮剂硅酸镁铝,还有钠基膨润土与羧甲基纤维素钠复配同钠基膨润土与黄原胶复配的效果对比;通过正交试验,极差分析以及涂料的各项性能指标,确定了涂料的最佳配比,并通过扫描电镜对涂层进行微观形貌分析。实验研究表明:(1)对于铝合金消失模铸造涂料,以硅藻土70%、莫来石30%的比例作为复合耐火骨料,悬浮剂钠基膨润土6%、CMC0.5%,粘结剂PVA1.5%、水玻璃6%,适量的添加剂和水,形成最佳配方。其综合性能达到消失模铸造涂料的要求。(2)新型悬浮剂硅酸镁铝的加入量对铝合金铸造涂料的流变性、悬浮性有很大的影响。当硅酸镁铝的加入量为0.5%-3%时,涂料的屈服值随着硅酸镁铝加入量的增大而逐渐增大,触变指数c在硅酸镁铝的加入量为1%-3%时也逐渐增大,涂料的流变性能得到提高。再者涂料的悬浮性与屈服值之间存在正相关的联系。最终确定了硅酸镁铝较佳的加入量为2%-3%,涂料表现出优异的悬浮性和流变性,悬浮性≥96%,触变指数c≥1.343。(3)对于镁合金消失模铸造涂料,以轻质氧化镁70%、滑石粉30%的比例作为复合耐火骨料,悬浮剂钠基膨润土2%、黄原胶0.3%,粘结剂PVM0.05%、水玻璃8%,硼酸锌4%,适量的添加剂和水,形成最佳配方。其综合性能达到消失模铸造涂料的要求。(4)在相同加入量下的CMC与黄原胶,当二者的加入量均在0.3%-0.7%范围时,加入黄原胶的涂料悬浮性、抗压强度以及流变性能优于加入CMC的涂料,流杯粘度也明显高于加入CMC的涂料,但当二者的加入量均为0.1%时,加入黄原胶的涂料的综合性能要逊于加入CMC的涂料。
[Abstract]:EPC is an important way to cast aluminum alloy and magnesium alloy. The casting coating plays an important role in casting quality, especially it can improve the surface finish and dimensional precision of casting. Reducing the possibility of defects such as pinhole, cold barrier, sand, sand, sand, carbon deposit, etc. But so far, there is no aluminum alloy and magnesium alloy dedicated EPC coating on the market, Therefore, two kinds of coatings with excellent comprehensive properties are developed in this paper. The refractory aggregate suitable for aluminum alloy and magnesium alloy is determined by testing the coating properties under different ratio of refractory aggregate. And optimized the ratio of refractory aggregate of coating, through the single factor experiment, studied the change of the performance of the coating after changing the amount of binder and suspending agent, determined the more suitable addition quantity of binder and suspension agent, In particular, mention was made of the effects of a new suspension, magnesium and aluminium silicate, and of sodium bentonite and carboxymethyl cellulose sodium mixed with sodium bentonite and xanthan gum, and of the performance of the coating through orthogonal tests, range analysis and coatings, The optimum proportion of the coating was determined, and the microstructure of the coating was analyzed by scanning electron microscope. The experimental results showed that the proportion of diatomite 70 and mullite 30% was used as the composite refractory aggregate for the aluminum alloy lost foam casting coating. Suspension sodium-bentonite 6 / CMC0.5, binder PVA1.5, sodium silicate 6, appropriate amount of additive and water, to form the best formula. Its comprehensive properties meet the requirements of lost foam casting coating. When the content of magnesium aluminum silicate is 0.5-3%, the yield value of the coating increases with the increase of the amount of magnesium aluminum silicate, and the thixotropy index c increases gradually when the addition amount of magnesium aluminum silicate is between 1% and 3%. The rheological properties of the coating were improved. Furthermore, there was a positive correlation between the suspension property and yield value of the coating. Finally, the optimum addition amount of magnesium aluminum silicate was determined to be 2-3. The coating showed excellent suspension and rheological properties. For magnesium alloy EPC coatings, the proportion of light magnesium oxide 70 and talc 30% is used as composite refractory aggregate. Suspension sodium bentonite 2, xanthan gum 0.3, binder PVM 0.05, sodium silicate 8, zinc borate 4, appropriate amount of additives and water, forming the best formula. Its comprehensive properties meet the requirements of EPC coating. When both of them were in the range of 0.3% -0.7%, the suspension, compressive strength and rheological properties of the coating with xanthan gum were better than those of the coating added with CMC, and the viscosity of the cup was obviously higher than that of the coating added with CMC, but when the addition amount of xanthan gum was 0.1%, the viscosity of the coating was also higher than that of the coating added with CMC. The comprehensive performance of the coating added xanthan gum is inferior to that of the coating with CMC.
【学位授予单位】：中北大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG22

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