Gold–Silver Electroless Plating on Laser Powder-Bed Fusion Additively Printed AlSi10Mg Parts

Abstract

The current research presents a novel methodology for surface finishing of printed AlSi10Mg parts by electroless deposited gold–silver (electrum) alloys. The parts were printed by additive manufacturing laser powder-bed fusion (AM-LPBF). The electrum was chosen due to its appearance and good electrical and thermal properties and was deposited on disk-shaped specimens at 80 and 90 °C. The coating quality and appearance were studied by different methods for various deposition times and film thicknesses. The results indicate that Au–Ag coatings of AM-LPBF AlSi10Mg yield satisfactory results. The XRD analysis revealed that the coatings were composed of Au–Ag crystalline phases and beneath them, a quasi-amorphous or mixed quasi-amorphous and nanocrystalline Ni–P interlayer. The mechanism of electrum formation was studied based on the XPS analysis results as a function of the temperature and concentration. At 80 °C, the Ag was dominant at the beginning of the deposition process, while at 90 °C the Au was first detected on the interface. This result was explained by the electrochemical properties of alloying metals and the binding energies required to form metal–Ni and Au–Ag bonding. The results indicate that the electrum coatings are satisfactory, and the developed surface finishing process could be used for many applications.

Gold, Silver, and Electrum Electroless Plating on Additively Manufactured Laser Powder-Bed Fusion AlSi10Mg Parts: A Review

“…A few studies have been published on the electrochemical deposition of Au-Ag alloy films [44][45][46][47]. However, no formulations of ELD for Au-Ag alloy coatings have been published in the open literature before Inberg et al 2020 [48].…”

“…For example, in some AM-LPBF AlSi10Mg items, additional coatings may be needed to improve electrical and thermal conductivity or to achieve a certain aesthetic appearance. The shiny and luxurious appearance of gold [43], silver [42], and electrum [48] plating can be used in numerous applications, among them replicas of ancient objects, such as valuable coins for museum presentations [42,43]. ELD of gold [49] and silver [50] metals can also be applied over AM fused filament fabrication (AM-FFF) acrylonitrile butadiene styrene (ABS) polymer objects when an appropriate chemical pretreatment process of the surface is done [49,50].…”

“…The objective of this research is to study the use of a novel environmentally friendly ELD finishing process by gold, silver, and electrum, of AM-LPBF AlSi10Mg parts, as a part of their post-printing surface modification. In addition, based on previous work of Dresler et al 2019 [42] and Inberg et al 2020 [43,48], this review aims to propose a methodology for effective Au, Ag, and Au-Ag ELD coatings of AM-LPBF AlSi10Mg objects. We should point out that one of the highlights of the technologies described here is the surface activation method.…”

“…A process for electroless Au-Ag plating on 3D-printed disk-shaped specimens was developed by Inberg et al 2020 (Figure 3) [48]. Prior to the deposition process, the oxide film (Figure 3a) that covered the AlSi10Mg surface was ultrasonically cleaned and etched for 10 min in a 12 g/L SDS solution at room temperature (Figure 3b).…”

On Additive Manufactured AlSi10Mg to Wrought AA6060-T6: Characterisation of Optimal- and High-Energy Magnetic Pulse Welding Conditions

“…The stationary specimens, 30 mm in diameter by 18 mm in length (Figure 2a,b), were built on an L-PBF machine (EOSINT M280 machine, EOS, Krailling Germany) equipped with a 250 × 250 × 300 mm 3 build-platform with an up to 400 W continuous Yb fibre laser. The parts ( Figure 2) were printed from a pre-alloyed AlSi10Mg powder with a particle size in the range of 20-63 µm and a layer thickness of 30 µm, with similar particle diameters used by Inberg et al [39]. The rods were built in the vertical (Z) direction ( Figure 2c) in an argon atmosphere with maximum oxygen content of 0.12%.…”