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(一) 前言目前国内部份动力装置中之冷凝器,其管材系采用国产∧68,∧O—70—1,∧A—77—2等数种,管细而长(内径一般为18—25毫米,长5米左右)冷却水流速约为1.5米/秒,一般在使用二星期至数月后即发现有腐蚀洩漏现象,迫使停机检修,以致影响生产。特别是当海水作为冷却剂时,腐蚀现象更为严重。观察解剖之现场黄铜管,内壁可见不规则之溃疡,少量二次铜的沉淀,以及马蹄形蚀痕。经金相观察,黄铜管之晶粒粗大,并有机械杂质,按R.May法测定黄铜管的耐蚀性能之结果:国产黄铜管 E_初-E_终=25-35mv 恢复时间2—2.5分鐘英国,日本黄铜管 E_初-E_终=5-10mv 恢复时间1—1.5分鐘上述结果说明国产黄铜管稳定性较差,在外界介质“冲击”下,电位迅速变负并在停止“冲击”条件下亦需要较长的时间方能复原。
(A) of the preface At present, some of the domestic power plant in the condenser, the pipe system using domestic ∧ 68, ∧ O-70-1, ∧ A-77-2 and so on, the tube thin and long (diameter is generally 18- 25 mm, length 5 meters) cooling water flow rate of about 1.5 m / s, usually two weeks to months after the discovery of corrosion leaks, forcing downtime maintenance, resulting in production. Corrosion is worsened especially when seawater is used as a coolant. Anatomical observation of the scene of the brass tube, the inner wall shows irregular ulcers, a small amount of secondary copper precipitation, and horseshoe-shaped etching. The metallographic observation, the brass tube of coarse grains, and mechanical impurities, according to R. May method to determine the brass tube corrosion resistance results: domestic brass E_ early-E_ final = 25-35mv recovery Time 2-2.5 minutes Britain, Japan brass tube E_ early-E_ final = 5-10mv recovery time 1-1.5 minutes The above results show that domestic brass tube stability is poor, in the external medium “impact”, the potential fast Become negative and take longer to stop before the “shock” condition can be restored.