The Study On Polishing Processing Of Al-Si Alloy And The Estimate Of Polishing Quality

Polishing is an important procedure in surface treatment of Al & Al alloy. After polishing, more smoothness and brightness surface of the product could be obtained and its decoration effect could be improved. Chemical polishing can't be used in the polishing of Al-Si alloy, because there is much silicon dust on its surface. Electrochemical polishing cost highly and its application is limited. While the spiral vibration polishing which has both chemical and mechanical effects gives Al-Si alloy product good polishing quality and satisfies market needs. Based on a lot of experiments and analysis, we got the following conclusion:Acid mixing ratio of HNO3 with HF and temperature are the two important factors that affect the acid pickling . The temperature effect on the acid pickling was studied and the best result is obtained. We found the better acid pickling process is the following: HNO3:HF=1:2, 8 minutes in winter ; HNO3:HF=2:1 , 20 seconds in summer and HNO3:HF=5:4, 40 seconds during spring and autumn. And the mechanism of acid pickling is studied using the X-ray Photoelectron Spectroscopy (XPS) and contour measure apparatus, SEM.Polishing agent for spiral vibration polishing is developed. The polishing agent is composed of surfactant, action agent, and water. And the effect of each component is also analyzed. Several kinds of surfactant are chosed and matched, including nonionic surfactant and negative ion surfactant. And the action of each ingredient is analyzed in details. All developed polishing agent ZPG-1, ZPG-2, ZPG-3 have good polishing effect.The advanced apparatus, XPS, SEM, rigidity apparatus and so on are used to evaluate the polishing quality. Lower degree of coarseness, higher varnish, and better capability to resist the cautery erode on the surface of Al-Si alloy is achieved.