Study On Preparation Technology And Properties Of Silver And Gold Coating On Stainless Steel Substrate

Usually, columnar polysilicon bar are prepared in Siemens method. The reductive furnace is a major reduction reactor, which is the most power consumption part of the entire process. In order to save energy in the production process, our subject attempt to produce silver or gold layer to reduce the heat radiation.There are four methods to produce layer, including plating, electric plating, vacuum ion plating, electroless plating. Only the plating method can be obtained both in laboratory and industrial implementation. Meanwhile, in order to obtain an excellent coating and apply on large reductive furnace without common cyanide and cyanide gold-plated silver-plated. So our reserch focus on the preparation and properties of non-cyanide silver plating layer and non-cyanide gold plating layer.Durning the process of the preparation of silver plating layer,we perform the comparative experiments to choose niacin as a complexing agent. To determine the optimum conditions, we considered about the three main conditions, including different niacin content, different content of primary salt, different content of potassium carbonate. The product are detected by electrochemical methods, micro-hardness testing, SEM and other means. The results show that negative potential of the electrodeposited is lowest when the ac niacin concentration was100g/L; deposition rate is fastest when the silver nitrate content of60g/L and the potassium concentration was95g/L. with the increase of acid content, coating at (220) preferred orientation increases. With the increase of the concentration of silver nitrate and potassium carbonate,the (111) crystal plane preferred orientation first increase and then decrease. What’s more, silver nitrate and potassium carbonate content have greater impacts on the corrosion resistance and microhardness.The main course of the experiment to test the main factors to the properties and the brightness of the layer in the progress of the sulfite system for gold plating. The results show that current density need to be kept low enough to avoid the decrease of the properties and brightness of the coating. Longer reaction time won’t help to increase the brightness of the layer. To save the cost,the thickness of the coating should be minimized. Of all the layers, the brightness of gold layer is most ideal. The microhardness and the deposition rate will reach the maximum level at the same time when the content of potassium sulfite is100g/L.