Abstract

Iron ore pellets are sintered and reduced in continuous large industrial oil-fired furnaces. From the furnace, large volumes of hot gas are sucked by powerful fans. Being exposed to gas-borne iron particles and temperatures ranging between 125°C and 328°C fan components are rapidly deteriorated. Extensive part repair or replacement are required for maintaining a profitable operation. The arc spraying technique has been suggested for repair provided it could produce erosion resistant coatings. Commercial wires were arc sprayed using various spray parameters to produce thick coatings. Arc-sprayed coatings and reference specimens were erosion tested at 25°C and 330°C and impact angles of 25° and 90° in a laboratory gas-blast erosion rig. This device was designed to impact materials with coarse (32 -300 μm) iron ore particles at a speed of 100 m/s. The volume loss was accurately measured with a laser profilometer. Few arc sprayed coatings exhibited erosion resistance comparable with structural steel at low impact angles. Erosion of arc sprayed coatings and reference specimens dramatically increases at 330°C for both 25° and 90° impact angles. Erosion-enhanced oxidation was found responsible for the increase in wastage above room temperature. Though arc spraying can be appropriate for on-site repair, the development of erosion resistant coatings is required for intermediate temperatures.

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