니켈기 자융성 합금 코팅의 방식특성에 미치는 후열처리의 영향

Abstract

Recently, it is required that high performance of corrosion resistance, wear resistance and thermal resistance of the materials used in machinery, oilfield and plant industry. Especially, metal and alloy easy to corrode from exposure to severe environment. Corrosion is one of the most common causes of fracture of structure. consequently, corrosion is the root cause of many individual economic calamities. In 1998, the total annual direct cost of corrosion in the U.S. was $276 billion. One way of prevent corrosion is thermal spray process. Coating by Thermal spray process can block the surface of material contacting outside environment. For this reason, thermal spray process is applied widely in many industrial areas. This study aims at investigating the effect of a fusing treatments on anti-corrosion characteristics of Ni-based self-flux alloy coating. Ni-based coatings were fabricated by flame spray process on steel substrates, and fusing treatments were performed using a vacuum furnace at 800℃ 900℃, 1000℃ and 1100℃. After fusing treatments, corrosion tests were carried out using potentiostat/galvanostat at solution with pH 2, pH 6, pH 8 and pH 13. Corrosion potential(Ecorr) and corrosion current density(Icorr) could be analyzed from polarization curve. After heat treatment, pores and boundaries in coating layer are decrease with heat treatment temperature increasing. Especially, treat temperature at 1100℃, The coating layer remolded and recrystallized. Fusing-treated coating at 1100℃ showed more favorable anti-corrosion characteristics than as-sprayed coating. Anticorrosive effect of fusing-treated coating at solution with pH 2 was relatively greater than coating at solution with pH 6 in acid solution. and Anticorrosive effect of heat-treated coating at solution with pH 8 showed more incorrodible characteristics than coating at solution with pH 13 in alkaline solution.