Erosion resistance of arc-sprayed coatings to iron ore at 25 and 315 degrees C

Iron ore pellets are sintered and reduced in large continuous industrial oi l-fired furnaces, From the furnace, powerful fans extract large volumes of hot gas. Being exposed to gas-borne iron ore particles and temperatures ran ging between 125 and 328 degreesC, fan components are rapidly eroded. Exten sive part repair or replacement is required for maintaining a profitable op eration. The are spraying technique has been suggested for repair provided it could produce erosion-resistant coatings. Conventional and cored wires ( 1.6 mm diameter) were are sprayed using various spray parameters to produce 250 to 300 mum thick coatings, Are-sprayed coatings and reference specimen s were erosion tested at 25 and 315 degreesC and impact angles of 25 and 90 degrees in a laboratory gas-blast erosion rig. This device was designed to impact materials with coarse (32 to 300 mum) iron ore particles at a speed of 100 m/s, The coating volume loss due to erosion was measured with a las er profilometer built by National Research Council Canada several years ago . Few are-sprayed coatings exhibited erosion resistance comparable with struc tural steel at low impact angles, Erosion of are-sprayed coatings and refer ence specimens dramatically increases at 315 degreesC for both 25 degrees a nd 90 degrees impact angles. Erosion-enhanced oxidation was found to be res ponsible for the increase in volume loss above room temperature. Though are spraying can be appropriate for on-site repair, the development of more er osion-resistant coatings is required for intermediate temperatures.