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Abstract In order to extend the service life of heating surface tubes of a boiler by increasing its wear resistance，
the technology of high velocity arc spraying are utilized to prepare wear-resistant coating of Ni55 on the surface of
SA-210C. The spray coating was remelted by a tungsten electrode argon arc welding machine and the microscopic
structure，phase composition，bonding strength，microhardness and erosion resistance of the substrate and coating
was investigated. The results show that the coating crystal is mainly composed of γ-（Fe，Ni）、Ni3Fe、CrB、
Cr7C3、Cr23C6、Fe3B and WC. The coating forms a typical lamellar structure during deposition，which is mainly
dominated by mechanical bond and has good compactness. The bonding strength of spray coating is 40.85 Mpa
which is prompted to 53.25 MPa after remelting. The average hardness of the spray coating is 1 081HV which was
also prompted to 1 143HV after remelting. In the conditions of erosion angle of 45°，erosion velocity of 200 m/s
and temperature of 600 ℃，the remelting coating has the best erosion wear resistance，and the spray coating has
better erosion wear resistance than substrate metal. The erosion wear behavior of the remelting coating is same as
brittle materials. The hard phases like CrB、Cr7C3、Fe3B are combined strongly with coating，which has the function
of resisting continuous cutting by abrasive grains. The erosion mechanism is the peeling of the oxide film and the
micro-cutting and ploughing of the substrate metal by the abrasive particles.
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Received: 27 February 2019
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2020, Vol. 30 
