Development Of New Metal Cored Materials For Surface Strengthening And Coating Properties

In order to achieve the effective protection of boiler tubes in coal-fired power plant, the arc sprayed coating was used in industry. However, in the most commonly used spraying wire system, as the Ni-based wire contains a high content of precious metals which increasing the cost, and the coating which was prepared by Fe-based wire has poor antistriping ability at high temperature and with the complexity process. Therefore, developing several new excellent erosion wear resistant ability, antistriping ability, and technological performance arc spraying wires is important for engineering application.This paper is on the basis of energy saving and improve the performance as the purpose, ferro-boron/ferrro-phosphorus and other powdered materials were wrapped up to get Fe-B and Fe-P tubular cored wires, and to obtain surface strengthening coatings for the effective protection of coal-fired boiler tubes by high velocity arc spraying technology.The microstructure, hardness law, thermal shock resistance and erosion wear resistance of the coating were tested and analyzed in this paper. The study showed that the coating surface forming well and macroscopic defects not obvious. Compared to the boron-containing coating, the phosphorus-containing coating did not significantly reduce the porosity and oxide content, but it made alloying process more fully in the process of coating deposition. When using stainless steel as the steel skin, the Fe-Cr solid solution and the fine dispersed intermetallics had olid solution strengthening and dispersion strengthening effect on the coating. The hardness of Fe-P coating(maximum was 794.8HV0.1) was lower than Fe-B coating(maximum was 1131.9HVo.1), but the antistriping ability was better than the latter, especially Fe79.88P16.04C4.08 coating had the best antistriping ability, the number of thermal shock up to 122 when cooling in air. The erosion wear experiment showed that Fe55.47B28.96Cr9.84Al3.82Ni1.91 coating with the best resistance of erosion wear, up to 6.4 times than the matrix Q235 steel, the coating surface was displayed pits with several "lips", and appeared radial cracks with tiny grooves for the secondary erosion. For Fe-P coating, the nonhomogeneity had great influence on the erosion wear resistance of the coating, Fe79.88P16.04C4.08 coating reached to 4.3 times than the matrix steel, there were elongated grooves on the surface after erosion wear experiment, this coating greatly reduced the production costs than the former.The arc sprayed coating which was preparaed by the two tubular cored wires with excellent antistriping ability at high temperature and erosion wear resistant ability, Fe55.47B28.96Cr9.84Al3.82Ni1.91 coating had successfully applied to protect the boiler tubes ektexine in coal-fired power plant, and Fe79.88P16.04C4.08 coating also may has a try.