| The rare earth elements have been widely used in many areas, and the material research workers have paid a great attention to the application of them for a long time. In order to make good use of rare earth resource and further improve the properties of the iron-base thermal spraying coatings, a systematic study of the effect of rare earth elements on the properties of arc spraying coatings was carried out ,its mechanism was analyzed, and several cored wires having high hardness, high wear-resistance and high bonding strength were developed. Through mixing the rare earths into iron-base thermal spraying cored wires and preparing coatings by arc spraying, the effect of rare earths on microstructure and wear-resistance of coatings was studied with the help of the optical microscope, the electronic mirror, the X-ray diffraction sets, the X-ray fluorescence apparatus, the hardness test sets, the wear test sets of rubber wheel, and other equipments and apparatus. The results proved that the rare earths can refine microstructure and increase hardness and wear-resistance. The rare earths can not work solely but together with boron, carbon and other alloy elements. There is a optimal rare earths content that is from 0.7% to 1.5% beyond which the effects of rare earths are limited. All above theses are helpful to expanding the application of rare earths in thermal spraying.Because iron-base materials having higher wear-resistance are sometimes used to protect some industrial boiler's parts which work in a relatively low temperature, heat shock and oxidation behaviors in low temperature of coatings were studied. The results prove that the rare earths can improve the oxidation-resistance of iron-base thermal spraying materials by restraining the shaping speed of oxidation membrane and increasing the peeling-resistance of oxidation membrane. The design B15 is optimal which consists of 1.5% rare earths in terms of abrasive wear-resistance and oxidation-resistance.
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