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임우조,황재호,김윤곤 釜山水産大學校 1994 釜山水産大學 硏究報告 Vol.34 No.1
In this study, the steel pipe piping water(SSPW) and SPPW on weldment were tested by using of a cavitation erosion - corrosion test appartus with nozzle(water tunnel type) and were investigated under the marine environment of liquid. The main results obtained were as follows 1) The corrosion - erosion of weldment is more susceptible than that of base metal. 2) The weight loss rate of heat affected zone of weldment can be largely improved by the preheat, dry of base metal and electrode before welding. 3) The electrode potential becomes noble by the pre-heat, dry of base metal and electrode before welding, and the corrosion current density is decreased.
임우조,황재호 釜慶大學校 1996 釜慶大學校 論文集 Vol.1 No.2
Cavitation is a hydrodynamic phenomenon which results in the formation and collapse of vapour bubbles in a liquid. The stresses produced when the bubbles collapse are considerable and severe erosion may occur to any solids in the vicinity. Cavitation damage is common in ship propellers, pump impellers and in the lubricating or cooling liquids of a vibrating machine such as a diesel engine. Both rotating disc and venturi devices are used to produce cavitation in the laboratory but the most convenient and commonly used devices are based on ultrasonic transducers and there is now a considerable amount of information on the cavitation erosion of materials. In this study, cavitation damage was investigated by using the piezoelectric vibrator with 20 kHz, 24㎛ to cavity generation apparatus. In order to investigate the reliablity for the cavitation erosion-corrosion test apparatus, the cavitation bubble group of test water was carefully measured with respect to test time. The photographs of the cavitation regimes were taken with a high speed camera arrangement by which the cavitation phenomena were studied. It is worth noticing in the vibratory cavitation apparatus that the cavitation bubble group does not fluctuate with test time. The result was ascertained by high speed photographs, which indicated uniform cavitation bubble group with test time.