Study On The Test Of Novolaks And Strengthening The Resin Coated Sand

The shell process has been developed greatly and takes the significant position in the foundry industry. In the future, it will be popularized and applied farther. But there are some problems on the shell process in our country and they need to be solved immediately.Firstly, a problem that will be solved in this paper is the lack of comparability and veracity due to the disaccord of test methods. As to this situation, we brought forward our own test methods under the current condition and found out the impacting rules by researching on the test methods. Secondly, another problem that will be solved in this paper is how to improve the intensity of resin coated sand used for shell process. The intensity is the more important index of performance of resin coated sand. As to the improvement of the intensity, there are two methods named internal and external enhancement mainly. The effect of external enhancement is more obvious and maneuverable. So the external enhancement was considered in the paper mainly. By a number of experiments on additives, we concluded a few enhancing rules and analyzed the principles at last.A few conclusions are as follows:During the test of softening point, the rate of heating-up affects the result evidently. The more higher rate of heating-up, the more higher value of softening point. The results that were tested by two different rate of the heating-up are quite discrepant. The principle can help us choose the proper rate of heating-up and provide the reference for constituting or improving the national standard of the softening point.The heating medium affects the result of the determination to some degree. The softening point in the bath glycerin is the less higher than that in the bath water. So we suggest determining the softening point used for shell process in the bath water when the softening point is under 95℃. We developed a kind of instrument of polymeric rate according the situation of laboratory. In order to get higher hot intensity, some parameters like the sand temperature 180℃, the mixing time after the resin was added to the mixture 100s, the time after the hardener was added 40s, the time after calcium stearate was added 30s should be chosen. But for intensity at room temperature, the parameters are 180℃, 80s, 30s, 20s separately.Additive 2 enhances the intensity of the resin coated sand distinctly. Additive 3 affects the intensity of resin coated sand obviously. We may choose 5% for the amount of the additive 2. It is reasonable that the amount of additive 3 is 1%. Through SEM and IR figures, it demonstrates that additive 2 and 3 make the neck being cohesive rupture mainly. At the same time, they have already been component of the resin so as to strengthen the resin film and improve the intensity of the resin used for shell process.