An automatic brush plating system was developed to eliminate the disadvantages resulting from the operator in conventional brush plating。 With this system, Ni/nano-Al2O3 composite coatings on 45 steel substrates were prepared from an electrolyte containing 20 g/l nano-Al2O3 particles。 For comparison, Ni/nano-Al2O3 composite coatings were also prepared manually。 Microstructure, surface morphology, microhardness, modulus and wear resistance of two Ni–matrix composite coatings were investigated comparatively。 Our present study shows that coating prepared automatically is much more dense, smooth, and uniform than that prepared manually。 The former exhibits better mechanical and anti- wear properties than the latter。79800

Keywords: Brush-plating; Automation; Composite coating

1。Introduction

Charles Dalloz and Georges Icxi designed the brush plating process in 1937 [1]。 An important milestone in the development of brush plating process was that the first North American commercial specification was issued for brush  plating  in 1956, thus formally recognizing brush plating process as a viable electroplating process。 Today, brush plating has gained widespread applications in engineering, especially for repair and maintenance。

Brush plating, also known as selective plating, or swab plating, is a very useful and portable method of contact plating。 In its simplest form, the brush plating process resembles paint- ing。 Brush plating equipment includes power packs, solutions, plating tools, anode covers, and auxiliary equipment。 The power pack has two leads。 One is connected to the plating tool and the other is connected to the workpiece to be plated。 The anode is covered with an absorbent material which holds the solution。 The operator dips the plating tool in the solution and then brushes it against the surface of the workpiece that is to be finished。 When the anode touches the work surface a circuit is formed and an electrodeposit is produced。 Plating

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occurs only where the anode contacts the workpiece。 During the brush plating process, the plating tool is always kept in motion whenever it is in contact with the work surface。 The movement will apply even plating on the entire area being plated and ensure a quality finish。 More detailed information about brush plating includes “Brush plating” by Norris [2], and “An update on brush plating” by Vanek  [3]。

Due to its portability, flexibility and easiness to operate, brush plating has found increasing use in industry。 Dini [4] summarized quantitative property data on a variety of brush- plated deposits, which offer promise in applications involving wear and/or corrosion resistance。 Subramanian et al。 [5,6] adopted brush plating technique to prepare tin selenide thin film on tin oxide coated conducting substrates at room temper- ature。 Xu et al。 [7] prepared Ni interlayer by brush plating before double glow plasma alloying of low carbon steel to enhance corrosion resistance。 Hu et al。 [8] used brush-plated Ni–W coating as interlayer to improve the adhesion and wear resistance。 Hui et al。 [9] reported that the wear resistance of brush-plated alloy Ni–Fe–W–S was superior to that of an electrodeposited chromium layer under dry friction at heavy load。 Ma et al。 [10] studied the tribological behavior of sulfu- rized olefin on Ni–P brush plating layers and found that the chemical reaction film NiS formed by the reaction of SO with Ni–P plating layer on wear surfaces possessed very good anti- scuffing and anti-wear properties。

Electrodeposited nickel composite coatings have widespread use in engineering, which conventionally have particles of a

The composition of electric brush Ni solution