| 摘要 |
From the time that they are immersed into a marine environment, bronze propellers are prone to attack by marine organisms, such as barnacles, coral and algae, which attach themselves to the bronze metallic surface, creating lumps on the propeller, which adversely affect its balance and cause impedance and vibration of the propeller and its boat in the water. Ant-fouling paints are either too toxic for the marine environment of lack smoothness on the surface. These problems have been overcome by a combination of known steps, namely, polishing the propeller to prepare it for electroplating, cleansing to remove all traces of dirt and grease, electroplating with copper to a depth of at least 0.005" or 0.15 mm, followed by spraying with a standard solution (5 %) of sodium hypochlorite and sodium chloride in a suitable container to form a firmly adhering conversion coating of basic cupric chloride and then sealing for at least twenty-four hours. The preferred procedure for polishing is 60# grit size at 3500 sfm for roughing, followed by 180# grit size at 5500 sfm for finishing using grease as a polishing aid. Electroplating with copper to the minimum depth provides a smoothing effect ranging from 70 to 90 per cent. The container in which the hypochlorite spraying is carried out is preferably kept sealed until just before fitting and launching. A life expectancy of five (5) years can be anticipated with minimal maintenance every time the vessel is slipped.
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