Cast iron pipe surface-modified for corrosion prevention and method of modifying the cast iron pipe surface for corrosion prevention

A method of modifying the surface of a cast iron pipe for preventing corrosion, in which the pipe has a corrosion preventive coating formed on the surface of its iron material, characterized in that,

• the method comprises thermal spraying of a quenched aluminum alloy onto the surface of the iron material of the pipe, the quenched aluminum alloy containing not less than 5 wt % but not more than 25 wt % of Mn, the remainder being Al, the quenched aluminum alloy being such that the manganese is present as a supersaturated solid solution in an aluminum phase and that intermetallic compounds comprised of manganese and aluminum are dispersed in an aluminum base, the thermal spraying being flame spraying so that the aluminum alloy is kept in a semi-molten state during spraying in which only the surface of the alloy is melted.