Non-Cyanide Electrodeposited Ag–PTFE Composite Coating Using Direct or Pulsed Current Deposition

Raymond Sieh,Huirong Le

doi:10.3390/coatings6030031

Abstract

The effects of FC-4 cationic surfactant on electrodeposited Ag–PTFE composite coating using direct or pulsed currents were studied using scanning electron microscope (SEM), energy dispersive X-ray (EDS), optical microscope, and a linear tribometer. FC-4:PTFE in various ratios were added to a non-cyanide succinimide silver complex bath. Direct or pulsed current method was used at a constant current density to enable comparison between both methods. A high incorporation rate of PTFE was successfully achieved, with pulsed current being highly useful in increasing the amount of PTFE in the composite coating. The study of coating wear under sliding showed that a large majority of the electrodeposited coatings still managed to adhere to the substrate, even after 10 wear cycles of sliding tests. Performance improvements were achieved on all the samples with a coefficient of friction (CoF) between 0.06 and 0.12.

Highlights

The properties of a substrate metal can be altered through the use of surface coatings as part of the metal finishing process
The work focused on the aspects of chemical changes through the addition of the cationic surfactant FC-4, as well as the changes in electrodeposition methods through the use of Direct plating (DCP) and Pulsed current plating (PCP)
The findings suggest that the initial high concentration of PTFE nanoparticles in the electroplating bath was beneficial in the high incorporation rates of PTFE across both DCP and PCP methods, ranging from 17–61 at % (4–33 wt %)

Summary

Introduction

The properties of a substrate metal can be altered through the use of surface coatings as part of the metal finishing process. These alterations may be to improve decorative or functional aspects of the substrate such as physical aesthetics, improved chemical resistance, or even improved mechanical properties. Electroplating is a high-performance, low-cost method of chemical deposition that is commercially viable and can be used in a wide variety of applications, from improving the aesthetics of a substrate to depositing semiconductors for electronics [4]. Recent research has highlighted the benefits of silver for various consumer and medical applications due to its anti-bacterial properties and biocompatibility [5,10]

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