Application of the Composite Hardness Models in the Analysis of Mechanical Characteristics of Electrolytically Deposited Copper Coatings: The Effect of the Type of Substrate

Abstract

The mechanical characteristics of electrochemically deposited copper coatings have been examined by application of two hardness composite models: the Chicot-Lesage (C-L) and the Cheng-Gao (C-G) models. The 10, 20, 40 and 60 µm thick fine-grained Cu coatings were electrodeposited on the brass by the regime of pulsating current (PC) at an average current density of 50 mA cm−2, and were characterized by scanning electron (SEM), atomic force (AFM) and optical (OM) microscopes. By application of the C-L model we determined a limiting relative indentation depth (RID) value that separates the area of the coating hardness from that with a strong effect of the substrate on the measured composite hardness. The coating hardness values in the 0.9418–1.1399 GPa range, obtained by the C-G model, confirmed the assumption that the Cu coatings on the brass belongs to the “soft film on hard substrate” composite hardness system. The obtained stress exponents in the 4.35–7.69 range at an applied load of 0.49 N indicated that the dominant creep mechanism is the dislocation creep and the dislocation climb. The obtained mechanical characteristics were compared with those recently obtained on the Si(111) substrate, and the effects of substrate characteristics such as hardness and roughness on the mechanical characteristics of the electrodeposited Cu coatings were discussed and explained.

Implementation of the Chicot–Lesage Composite Hardness Model in a Determination of Absolute Hardness of Copper Coatings Obtained by the Electrodeposition Processes

“…During hardness analysis of the Cu coatings electrodeposited by the PC regime on Si(111), the calculated values of the coating hardness by the C-L model were multiple times larger than the composite hardness at the applied low indentation loads [21]. The similar situation was also observed during the hardness analysis of Cu coatings of various thicknesses electrodeposited by the same regime on the brass substrate [22]. For Cu coatings electrodeposited on the brass, this anomaly was successfully solved by defining a limiting or critical relative indentation depth (RID) value of 0.14 which separates the area in which a composite hardness corresponds to the absolute hardness of the coating and the area where application of the composite hardness model was necessary for the determination of the absolute coating hardness.…”

“…All electrodepositions were performed in an open cell of cylindrical shape with an electrolyte temperature of 22.0 ± 0.50 • C. Two types of cathodes were used: Si(111), and brass (260 1/2 hard, ASTM B36, K&S Engineering). The preparation of Si(111) and brass cathodes for copper electrodeposition is described in previously published papers [21,22]. The cathodes of (1.0 × 1.0) cm 2 surface area were positioned in the center of the cell.…”

“…The hardness values of Si(111) and brass cathodes have been already determined applying the PSR (Proportional Specimen Resistance) model [27], and they were 7.42 GPa for Si(111) [21] and 1.41 GPa for the brass B36 [22] substrates. The Chicot-Lesage (C-L) composite hardness model was used for a determination of the absolute hardness of the Cu coatings.…”

Advances in Design by Metallic Materials: Synthesis, Characterization, Simulation and Applications

“…The collection includes papers regarding the most multifaced aspects of metals as synthesis [1][2][3], treatments [2][3][4], experimental characterization [4][5][6][7], material models [7][8][9] and engineering applications [10][11][12] providing a clear cross-section of the wide variety of topics and research arguments under investigation in the scientific community now.…”

“…This kind of erosion is rather uncommon in terms of present contributions to the state of the art, while it is quite frequent in practical applications (such as marine engineering, oil and gas applications and so on). However, surface hardening and wear continues to represent a relevant aspect to take care on in the use of metals, as demonstrated in [6] where metal matrix composites are experimentally investigated or in [8] where numerical models are developed in a way that predicts the final effect of hardening treatments. Numerical models, sometimes powered by finite elements, are also present in other contributions with the scope to predict plasticity [9] or failures [10] or, even, to support design actions with the scope to optimize the use of metal structures [11].…”