摘要:The effects of the polyvinyl alcohol (PVA) , sodium silicate and bentonite contents on the permeability of washings at room temperature (K1) and after high temperature heating (K2) were studied. The results shaw that as the content of PVA increasing , K1 possesses a peak value, and K2 rises, as the content of sodium silicate increasing, K1 descends and K2 possesses a peak value, as the content of bentonite increasing, K1 descends and K2 increases.
摘要:It is found that the alloy elements Mg, Cu and the aging time have great influences on the mi-crostructural transformation of Zn-27%Al alloy. Mg would restrain the solid transformation of α and β phases, but Cu would accelerate them, hence these alloying elements can also affect that the corrosion performance of ZA27. According to the results of salt spray test, it is given that the proper contents of alloy elements are: Mg, 0.03%-0.20%; Cu, 0.5%-2.5%, the optimal aging time at 250℃ is about 2 hours.
摘要:A meltable pattern material with higher bending strength and hardness. and a coating material for preventing the sand, core from polluted by the molten pattern have been developed. The coated twisty blade patterns possesses higher bending strength and hardness than the uncoated ones. This would meet the requirements of core making both the surface roughness and the dimensional accuracy on the flow-passage of the cast blade wheel can satisfy the standard requirements.