Crystallisation and performance characteristics of high-temperature annealed electroless Ni-W-P coatings

H. Liu, HL Yao, Y. Liu, GE Thompson, Z Liu

    Research output: Contribution to journalArticlepeer-review

    Abstract

    Electroless deposition of Ni-P based alloys is a well-known commercial process that has numerous applications because of their excellent anticorrosive and wear properties. However, for some special occasions, like the components for gas making furnaces in chemical fertiliser industry, the coatings must be reinforced to withstand short-term high temperatures between 600 degrees C and 700 degrees C as well as light erosive wear. Therefore, co-deposition of high melting point metallic element, W, has been considered as a preferred choice. In the present study, two Ni-W-P alloy coatings were deposited on mild steel panels from different alkaline baths. The microstructures of the annealed coatings were characterised by quantitative XRD, XPS and SEM/EDS analysis techniques and their microhardness, friction and wear behaviour, corrosion mechanism as well as microstrain and residual stress are discussed in comparison with the as-plated state. The results indicate that the hardness mainly depends on the volume fraction and crystallite size of Ni3P phase; the uniform corrosion in sulfuric acid solution is closely related to the ratio of I-Ni/I-Ni3P as well as grain size. The wear mechanism of the high-temperature annealed coating is dominated by abrasive wear, but the wear in the early stages started from mild adhesive wear caused by adhesion between the friction couples. Electroless deposited Ni-W-P alloys with high phosphorus present relatively good properties, including hardness, wear and corrosion resistance when 700 degrees C is applied for annealing process.
    Original languageEnglish
    Pages (from-to)178-189
    Number of pages11
    JournalCrystal Research and Technology (Print)
    Volume49
    Issue number2-3
    DOIs
    Publication statusPublished - Mar 2014

    Keywords

    • electroless Ni-W-P; high temperature annealing; crystallisation; performance characteristics

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