中大型 高速 船舶用 러더의 耐浸蝕·腐蝕 特性 向上을 위한 溶射 코팅膜 開發에 관한 硏究

Abstract

Recently domestic heavy industries, shipbuilding companies become to be interested in a developing long life cycle for the vessel and marine structures with effective maintenance rate and endurance properly. Especially, vessel and marine structures require special corrosion control because they tend to be exposed to extreme corrosive environment. Most of the surfaces of vessels and marine structures are being coated with same process of anti-corrosion paint so far because ship speed is less than 20 knot usually.

However, shipbuilders have to upgrade a performance of new ship or vessel matching customer’s requirement to build it bigger and faster. Therefore corrosive level on the vessel and marine structure becomes not a simple corrosion matter any more. Currently, corrosion environment on the marine vessel becomes to be more complex and extremely poorer than the past.

A rudder, one of the most important components in the vessel, is now being decreased life time to serve due to cavitation erosion, vortex current, high flow speed suffer from ship speed going up dramatically. Container carrier, LNG carrier, navy ships have problems to maintaining the rudder and propeller because service period and dry dock interval have been shortening from 3~5 year to 3 month due to heavy corrosion and erosion damage. In this situation, it is necessary to develop an innovative surface coating instructions.

In this study, mainly the improvement of thermal spray performance which has applied to general industrial fields already is focused by comparing, analyzing, predicting corrosion orientation, corrosion rate. In addition, this study intends to give a direction of optimized design to improve the prevention from surface corrosion, cavitation erosion furthermore.

At first, 10 kinds of thermal spray coating materials(2 of Zn alloy series, 3 of Al alloy series, 3 of Cu alloy series, 2 of stainless steel alloy series) are chosen to apply on specimens and analyze micro structure, metallic composition, properties(porosity, oxidation) by using visual observation, XRD, EDX. Additionally, to refine the characteristic of corrosion endurance for thermal spray coating layer, compared with thermal spray process and 5 kinds of heavy duty painting and a kind of AC paint (anti-corrosion paint).

Based on above mentioned experimental results, a priority of all coated specimens on corrosion-erosion endurances is finalized and summarized there by desirable composition and process of thermal sprayed material is properly.