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Microstructure and high temperature abrasion resistance of WC-reinforced composite coating produced by PTA weld-surfacing process
摘要
Many parts in steel industry commonly failed due to being subjected to the abrasion and corrosion conditions even with mechanical impact or high temperature atmosphere,which requires efficient surface-protection coating deposited on the parts in order to avoid costly downtime and to reduce costs for expensive spare parts.In past literature,many hardfacing techniques such as build-up welding,thermal spraying and laser cladding have been widely used for above demands.This paper introduces a new coating process plasma transferred arc ( PTA) weld- surfacing with some specials : larger selection range of coating component and depositing composite coating like Nickel-based or Cobalt-based cermet due to using powder feedstock compared to conventional build-up welding technique,lower production cost,higher productivity and thicker coating layer while compared to laser cladding layers,in addition to superior coating-substrate interface to thermal spraying coating.In this paper,a Nickel-based PTA overlay reinforced with 60 wt% of tungsten carbides ( WC) was produced to enhance the surface properties of DRI screw and DRI distributor in Baosteel COREX blast furnace.Microstructure observation from optical microscopy and scanning electronic microscopy ( SEM) indicate that the WC particles which mostly maintain original shape and exhibit few dissolution,distribute uniformly across the section of the layer.The microhardness of the Ni-based matrix is about 580 ~ 650 HV0.45.The wear tests under high temperature of 600℃ show that the Ni- based alloy reinforced with 60 wt% of WC particles exhibits good wear-resistance performance,which is attributed to the inherent high hardness and high volume fraction as well as uniform distribution of the primary tungsten carbides within the Ni-based matrix.
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