| Furan resin, as a kind of adhesive, is widely used in the field of foundry. The performance of furan resin is not only related to the performance of furan resin itself, but also related to curing agent which is used with furan resin together. In this paper, the respective advantages of organic sulfonic acids and inorganic curing agents are combined to reduce their own shortcomings. The purpose of this paper is to develop a series of composite curing agents with environment-friendly and high-performance, through researching the effects of the system of curing agent on curing properties of furan resin. Meanwhile, the performance of this curing agent also is investigated.The results of this research in this paper mainly include three following aspects:(1) The effects of the system of curing agent on curing properties of furan resin were researched by the single factor analysis method, thus the curing agent which has good solubility, good volatility, and environment friendly can be chosen. A series of curing agents which can meet the requirements were prepared conveniently by using the combination of theoretical and experimental method in order to meet the application requirements under different conditions. The results show that when the solvent of curing agent is methanol-water solution (1:1), the final tensile strength is up to 1.5 MPa which is increased by about 40% compared with other curing agents. When the organic acid component of curing agent is concentrated sulfuric acid, there is no gas generated, and it also has a wide range of the total acidity which can be adjusted to more than 60%. The curing agent containing 20% P-toluene sulfonic acid by weight has a final tensile strength up to 1.6 MPa and the surface of the sand mould is very tight and compacted without the phenomena of sand falling.(2) The effects of the addition of furan resin, curing agent, temperature and humidity on curing properties of furan resin and the effects of the total acidity on bench time and stripping time were studied by the single factor analysis method. Through comparing the tensile strengths of cured furan resin by different modes of operation, the reasonable mode of curing process operation was determined. The results show that the optimal addition of furan resin is 1.0～1.2% of the sand by weight and the optimal addition of curing agent is 40～50% of furan resin by weigh. When the temperature is dropped from 45℃ to 20℃, the initial tensile strength and the final tensile strength are decreased by 41%,3% respectively. When the humidity is raised from 40% to 70%, the initial tensile strength and the final tensile strength are all decreased by around 40%. The suitable temperature and humidity of curing condition are at 20～30℃,50～60% respectively. And the bench and striping time both increase with the increment of the total acidity of curing agent. During the operation of curing, the method of a continuous feed and adding curing agent firstly, adding furan resin secondly is adopted, which can increase the final tensile strength by around 20% compared with other modes.(3) Through testing the change of the appearance and performance indexes of curing agent over time and temperature, the stability of curing agent and the effects of the temperature on curing agent were researched. The results show that when the composite curing agent stores for a long time, the stability of appearance and performance indexes of the curing agent are more stable and performance indexes change within ±5% in the largest range. |
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