Study On New Heat And Wear Resistance Cored Wires For High Velocity Arc-spraying

Using high velocity arc-spraying to prepare the heat-resistant and wear-resistant coatings has obvious advantages in the protection of boiler heating surface.However,in order to avoid the cracking and peeling of the spray coating,the coating composed of Ni-Mo or Ni-Al alloy bottom layer and the heat-resistant and wear-resistant working layer is usually used in industry circle,which makes the material cost higher and the construction process more complicated.Therefore,in this paper,four kinds of iron-based cored wires are designed and prepared,including Fe/Cr,FeBCrAlNi/B₄C,FeCr BSi?Mo/W?and FeCrMoWCuNiAl?Co?/B₄C.And high velocity arc-spraying technology is used to spray directly on the Q235 substrate.The result shows that the prepared coatings are well formed and have no cracks and peeling in macroscopic.In order to investigate the relationship between the composition,microstructure and properties of coatings,the hardness,thermal shock resistance,high temperature oxidation resistance,sliding friction-wear resistance and high temperature erosion-wear resistance is tested.The optical microscopy,scanning electron microscopy?EDS?,X-ray diffraction?XRD?and synchronous thermal analyzer is used to analyze the composition of the coating.The research shows that every coating shows a typical layered structure.The average hardness of Fe/Cr coatings is in the range of 503.60⁵94.56 HV_0.1.The hardness and oxidation resistance increases with the increase of Cr content.The coating with 25% Cr content has the excellent oxidation resistance.In FeBCrAlNi/B₄C coatings,B₄C improves the hardness of coatings observably.The hardness increases from 786.82 HV_0.1 to 1006.58 HV_0.1 with the B₄C content increasing from 0% to 6%.But when it reaches 9%,the hardness decreases to 741.45 HV_0.1.The thermal shock resistance and high temperature erosion-wear resistance of coatings is relatively better.It is found that there is a certain amount of amorphous phase in every FeCrBSi?Mo/W?coating,and the average hardness of the coatings is between 646.95⁹10.37 HV_0.1.Among them,the organization of FeCrBSiW?WC?coating is most dense,and the coating contains 24% amorphous phase with the crystallization temperature of 513.9?,and the hardness of this coating is highest.It shows that FeCrBSiW alloy system has stronger ability to form amorphous under spraying conditions.And the thermal shock resistance,sliding friction-wear resistance and high temperature erosion-wear resistance of this system is better,while the high temperature oxidation resistance is lower.The hardness of FeCrMoWCuNiAl high-entropy alloy composite coating is low,which is between 415.87⁶85.29 HV_0.1.And thermal shock performance and high temperature oxidation resistance is poor.