Synthesis, characterisation and thermal behaviour of Cu-based nano-multilayer

Abstract

Cu/AlN–Al2O3 nano-multilayer (NML) was deposited by magnetron sputtering method on 42CrMo4 steel samples, starting with a 15 nm AlN–Al2O3 layer and followed by 200 alternating layers of 5 nm thick Cu and 5 nm thick AlN–Al2O3 layers. The microstructure and thermal behaviour of the as-deposited and heat-treated multilayer was studied. Starting from about 400 °C, extensive coarsening of Cu nanocrystallites and the migration of Cu within the multilayer were observed via solid-state diffusion. Part of the initial Cu even formed micron-sized reservoirs within the NML. Due to increased temperature and to the different heat expansion coefficients of Cu and the AlN–Al2O3, the latter cracked and Cu appeared on the top surface of the NML at around 250 °C. Below 900 °C, the transport of Cu to the top surface of the NML probably took place as a solid-state flow, leading to faceted copper micro-crystals. However, above 900 °C, the Cu micro-crystals found on the top of the NML have rounded shape, so they were probably formed by pre-melting of nano-layered Cu due to its high specific surface area in the NML. Even if the Cu crystals appear on the top surface of the NML via solid-state flow without pre-melting, the Cu crystals on the top surface of the NML can be potentially used in joining applications at and above 250 °C.

Spontaneous inversion of the submicron ceramic layer deposited on steel and the copper droplet positioned on their top (case of ceramic poorly wetted by liquid Cu)

“…However, let us note that EDS in not particularly suitable for accurate quantitative analysis of O and N contents. The complex phase-structure of the AlN-Al 2 O 3 coating obtained under identical conditions was discussed in details in our previous study [16].…”

“…Figure 11 Calculated phase diagram of the copper-oxygen system [16] based on data by Barin [32] with p1 being the interval of oxygen partial pressures during our wetting experiments and point w corresponding to the working point in our experiments.…”

“…It can be stated that although the results of the above observations are similar, the underlying mechanism is different depending on the characteristics of the investigated system and the experimental conditions. In our previous study [16], the micro-and nanostructure of the magnetron sputtered Cu/AlN-Al 2 O 3 NMLs were investigated and their thermal behavior was characterized in details. The current study focuses on the wetting behavior of the Cu/ AlN-Al 2 O 3 /CrMo4 steel system, explaining and modeling the observed phenomena.…”

Boride Coatings on Steel Protecting it Against Corrosion by a Liquid Lead-Free Solder Alloy

“…The contact angle of the lead-free solder droplet was measured with the use of KSV software following the Young-Laplace method. [53] The contact angle values measured on the right and left sides of the solidified solder droplet silhouette were averaged. The tolerance in the case of wetting investigations was within ± 3 deg.…”

Enhanced Wetting and Adhesive Properties by Atmospheric Pressure Plasma Surface Treatment Methods and Investigation Processes on the Influencing Parameters on HIPS Polymer

“…Further interface property may be the wetting ability of a surface [ 6 ]. It may be necessary to have a surface that repels liquids such as car windscreens with rain, oil impregnating of mechanical parts, or a surface that has good wetting property [ 7 , 8 , 9 ]. A good wetting property means that a liquid can spread fully on the surface [ 10 , 11 , 12 ].…”