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Tribological behaviour of electroless Ni-W-P deposits
Suresh Krishnamoorthy Seshadri
Published in
2004
Volume: 2004
   
Pages: 109 - 114
Abstract
Electroless nickel (EN) plating has received attention as a hard coating for industrial applications due to its high hardness, uniform thickness as well as corrosion and wear resistance. The electroless Ni-P deposit is a supersaturated alloy in as-deposited state, and can be strengthened by precipitation of nickel phosphide crystallites with suitable heat treatments. However, the hardness of Ni-P films degrades with excessive annealing due to grain coarsening. An alternative to Ni-P coatings (in both as plated and heat treated conditions) can be the ternary alloy with the addition of a third element to the binary Ni-P system. The ternary Ni-M-P alloy, where M is typically a transition metal such as W, Co, Mn, Re and Mo have superior properties compared to the binary Ni-P alloy and therefore, could extend its range of applications. The present paper discusses the synthesis and tribological behaviour of Ni-P and Ni-W-P deposits. Deposition was done in an electroless bath maintained at alkaline pH of 8.5. Deposits with varying content of tungsten were synthesised. Chemical analysis shows that tungsten incorporation reduces the phosphorus content in the deposit. Phosphorus content varied from 3 to 7 wt.% depending upon the tungsten incorporation in the deposit which in turn varied between 5 to 18 wt.%. Hardness of the coatings with high tungsten (18 wt.%) content was 950 HV200. Coatings with high tungsten content exhibit very good wear resistance compared to binary Ni-P as well as low tungsten ternary alloy deposits. Copyright © 2004 by Society for Advancement of Heat Treatment & Surface Engineering (SAHTSE),.
About the journal
JournalProceedings of the International Conference on Advances in Surface Treatment: Research and Applications, ASTRA
Open AccessNo
Concepts (15)
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    Annealing
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    Binary mixtures
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    Chemical analysis
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    Corrosion resistance
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    Heat treatment
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    Industrial applications
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    Nickel
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    Ph effects
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    Tribology
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    Wear resistance
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    PHOSPHIDE CRYSTALLITES
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    SUPERSATURATED ALLOY
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    TERNARY ALLOY DEPOSITS
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    TRIBOLOGICAL BEHAVIOR
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    Electroless plating