【作者】 张祎林；

【导师】 李英民； 刘伟华；

【作者基本信息】 沈阳工业大学 ， 材料加工工程， 2012， 硕士

【摘要】 随着人们对环保要求的提高,开发无污染、高效率的铸造粘结剂成为迫切要求。动物胶是一种无污染、可生物降解的水溶性粘结剂,具有来源广泛,成本低廉,无污染等优点,有很广的应用前景。动物胶直接用作铸造粘结剂的效果很差,需要对动物胶进行改性。本文通过将普通的动物骨胶进行改性处理,制备成一种铸造型芯粘结剂,其室温下呈液态,并可通过吹入CO₂气体进行硬化,建立起较高的工艺强度。首先通过试验,确定合适的分解工艺。碱性催化剂具有分解动物胶高分子化合物速度快的特点,选择NaOH为催化剂,最佳加入量为动物胶质量的4%,碱解温度为50℃,碱解时间为30min,水胶比为4:5。接下来采用接枝共聚和酯化交联等方法,进行动物胶的改性,使其具备更高的吹气硬化强度。通过试验,选择了丙三醇和糊精、无水乙醇作为改性剂,并采用正交试验方法,确定了动物胶粘结剂的最佳配比和工艺参数。新型改性动物胶粘结剂的最佳工艺为:m（丙三醇）:m（糊精）:m（无水乙醇）:m（动物胶）=9:10:9:100,改性温度75℃,改性时间90min。通过红外光谱对新型改性动物胶粘结剂进行分析,表明改性动物胶已经发生了接枝共聚和酯化反应。新型改性动物胶粘结剂可通过吹CO₂气体硬化,粉状Ca（OH）₂作为硬化促进剂。新型动物胶粘结剂加入量3.5%,促硬剂Ca（OH）2粉末加入量1.25%,吹气量0.7m3·h-1,吹气时间60s,混砂时间为150s,试样初强度可达0.8 MPa,终强度可达6.0 MPa。通过扫描电镜对粘结桥断面形貌进行了分析,并对吹气硬化机理进行了理论分析。最后通过试验测定了新型改性动物胶型砂的可使用时间、发气量、存放性和溃散性等工艺性能。该型砂具有较低的发气量,良好的存放能力和高温残留强度。通过经济性分析,新型动物胶粘结剂相对于三乙胺冷芯盒粘结剂有较大的经济优势,为开发新型动物胶铸造粘结剂提供了一条新的途径。更多还原

【Abstract】 With the increased awareness of environmental protection requirements, a non-toxic, non-polluting, low-cost foundry binder is an urgent requirement. Animal glue is a water soluble binder which is non-toxic,pollution-free and biodegradable. The animal glue has some advantages, such as extensive sources, low cost, pollution-free and so on, and has a spacious prospect in application. When the animal glue was directly used as a binder for foundry,a poor result could get , so it needs to be modified. In this paper, the ordinary animal bone glue was modified by a modification and a new binder for foundry, which was liquid at room temperature, cured by CO₂ was prepared with a higher bonding strength.First, the appropriate decomposition process was determined through the tests. A alkaline catalyst has the feature of rapid decomposition speed. NaOH was chosen as catalyst and the optimum addition amount of NaOH is 4% of animal glue content, the temperature of alkaline decomposition process was 50℃, the period of time was 30 min.Next, the grafting polymerization and esterification crosslinking methods were applied to modify the animal glue, which made the core sands of animal glue have higher strength cured by gas. Through lots of experiments, glycerin, dextrin and ethanol were chosen as modifiers finally, and an orthogonal experiment was done to determine the best proportion of them and the process parameters for the preparation of the animal glue binder. The best technology of new modified animal glue binder agent is : m （glycerin） : m （dextrin）: m （ethanol）:m （animal glue） = 9:10:9:100, water-animal glue ratio is 4:5, modification temperature is 75℃and modification time is 90min. By the infrared spectrum, the new modified animal glue binder was characterized and the results showed that the modified animal glue had been modified by a grafting copolymerization and an esterification reaction.Through the tests, the way of cured by CO₂ for the new modified animal glue binder was adopted and Ca （OH）2 in powder was used as a cure-promoter. The addition of new animal binder is 3.5% to sand the addition of Ca （OH）2 is 1.25%. A good flow of CO₂ is 0.7m3·h-1, a good period of time for blowing CO₂ is 60s and the mixing time of sand is 150 s. The original strength of the binder is above 0.8 MPa and its final strength is 6.0 MPa. By scanning electron microscope, the feature of bonding bridge was analyzed, and the gas-cured mechanism was analyzed in theory.At last, tests on the performance of new modified animal glue binder sand were done, such as the serviceable time, gas evolution, storage capacity and collapsibility of core. Through the tests, it was found that the sand has a low gas evolution, a good storage capacity and a low residual strength of high temperature. Through economic analysis, compared to the triethylamine cold box binder, which has widely application in the market, the new type of animal glue binder has an economic advantage, and which provides a new way in development of binder for foundry.更多还原