Braze Material Research Articles

Wetting Behaviors of Al-Si-Cu-Mg-Zn Brazing Materials on 5083 Aluminum Alloy

The wetting behaviors of Al-Si-Cu-Mg-Zn brazing materials on 5083 aluminum alloy substrate were investigated through changing the proportion of Mg from 0 to 2 wt.%. The experimental results showed that the welding process goes through the three following stages: slow spreading, fast spreading, and stabilizing. The wettability of the brazing material was improved effectively, and the porosity of the interfacial layer was reduced, with the addition of Mg. With Mg content at 1 wt.%, the wetting diameter reached a maximum value of 20.46 mm. The reaction mechanism of the wetted interfacial layer between the brazing material and substrate alloy was illustrated with dynamic data, provided through experimentation and simulated thermodynamic calculation, and showed that the wetting behavior of the resultant Al-7.5Si-15Cu-1Mg-5Zn brazing material was dominated primarily by a diffusion reaction from elemental magnesium.

Exploring W-EUROFER brazed joints: S/TEM and nanoindentation analysis following post-brazing tempering treatment

Tempering treatments are essential for restoring the hardness and microstructure of EUROFER steel when W-EUROFER joints are formed at temperatures exceeding the steel's austenitization point (890 °C). This post-brazing heat treatment can, however, alter the microstructure and thereby affect the mechanical properties. This study explores the microstructural and nanomechanical effects in the brazed area of W-EUROFER joints following this heat treatment, utilizing copper as an intermediate filler material. Using Scanning Transmission Electron Microscopy (STEM) with Energy Dispersive Spectroscopy (EDS) on FIB lamellae and nanoindentation techniques we examined the stability and phase characteristics of the post-tempered microstructure in two lamellae that covers the whole phases of the braze microstructure.The tempering process enhances copper diffusion and the growth of copper precipitates without significantly altering the joint's overall microstructure. Despite the general stress-relief effects of tempering, which typically lower mechanical properties, the diffusion phases formed during brazing maintained high hardness and modulus, indicative of a complex, element-rich composition. A reduction in mechanical properties was observed in the iron-rich phase near the W-braze interface and the EUROFER base material, aligning with the purpose of the heat treatment. However, the copper braze and tungsten base material largely retained their stability and resilience to thermal treatments.This research provides vital insights into the behavior of these material systems under thermal processing, highlighting the necessity of optimizing heat treatment parameters to preserve joint integrity in high-performance applications such as nuclear fusion reactors. The findings contribute significantly to the development of durable and reliable materials for fusion energy, emphasizing the importance of controlled tempering processes to enhance material properties.

Deuterium permeation and retention behavior in copper-based brazing filler materials

Copper-based brazing filler materials are commonly employed in vacuum brazing techniques to achieve joining of plasma-facing components for ITER. In this work, gas-driven permeation (GDP) and thermal desorption spectroscopy (TDS) experiments have been performed to study the hydrogen isotopes permeation and retention behavior in two types of brazing filler materials (CuMnNi and CuGeNi metals). Experimental results show that CuMnNi filler exhibits the similar deuterium (D) permeability with CuMnNi filler but lower diffusion coefficients than CuGeNi filler. Three distinct peaks are observed between 380 K and 980 K for CuMnNi filler. However, no evident desorption peak is observed for CuGeNi filler. CuGeNi filler may be considered as a potential brazing filler material for reducing tritium inventory.

Study on microstructure and mechanical properties of 3003 aluminum alloy joints brazed with Al–Si–Cu–Ni paste brazing materials

Paste-type brazing materials have advantages such as adjusting the complexity of the parts to be soldered, easy storage and production in certain quantities. They can be used for brazing heat exchangers, liquid tanks and corrosion resistant parts. In this work, the microstructures and thermal behaviors of Al–Si–Cu–Ni brazing materials with different contents were investigated, and the effect of brazing process on the microstructural evolution and mechanical properties of brazed joints produced under nitrogen-filled environment was examined. It was found that the melting temperature of brazing material Al–5Si–20.5Cu–2Ni were ranged from 512.86 to 549.37 °C. The microstructure of Al–5Si–20.5Cu–2Ni consisted of α-Al solid solution, CuAl2 intermetallic compounds, the Al–Si–Cu phase, and some fine irregular Si particles in a homogenous manner. The microstructure of the brazed joints was uniformly formed during the brazing condition of 580 °C for 20 min, and the shear strength of the joints reached 41.76 MPa.

Optimized design of composition and brazing process for Cu-Ag-Zn-Mn-Ni-Si-B-P alloy brazing material based on machine learning strategy to improve brazing properties

As brazing devices become more sophisticated and service environments become more demanding, Cu-Ag-Zn-Mn-Ni-Si-B-P brazing material are subjected to higher wettability and brazed joint strength requirements. In this paper, a machine learning strategy is proposed. Firstly, the composition-process-properties dataset is obtained based on high-throughput experimental techniques. Then, the composition features are constructed by elemental chemical and physical parameters instead of the direct input of alloy composition, and the proposed novel feature selection method is used to effectively identify the key composition feature combinations that affect brazing properties. Then, the support vector regression algorithm was used to establish a joint strength model with an error of less than 3.47 % and a spreading area model with an error of less than 8.37 % using the key alloy composition features and brazing process features as inputs, respectively. Finally, two multi-objective optimization strategies, Bayesian optimization and NSGA-II genetic algorithm, were used for the integrated optimization design of composition and brazing process. The experimental results show that the Cu-14Ag-4Zn-24Mn-13.5Ni-0.4Si-0.3B-0.3 P alloy and the matched brazing process (945 °C and 12 min) were optimally designed using NSGA-II genetic algorithm, corresponding to the measured joint strength and spread area of 356 MPa and 412 mm2, respectively, which outperforms the high-throughput experimentally optimized data as well as commercialized data. The machine learning strategy established in this work provides a new research idea for the comprehensive improvement of brazing properties of brazing alloys with small data sets.

Microstructure and shear strength of SiC/Zr joint brazed with LiAlSiO4/graphene-coated Cu-foam composite interlayer

In the present work, the microstructures and mechanical properties of Cu-foam-(graphene, LiAlSiO4 and graphene/LiAlSiO4) and a CoCrNiFeCuSn high-entropy alloy as a composite interlayer for brazing Zr and silicon carbide (SiC) ceramics are explored. Further, the effects of graphene, LiAlSiO4, and graphene/LiAlSiO4 on the mechanical properties and microstructure of the SiC/Zr joint are investigated. The results of the data analysis reveal a good connection between SiC and Zr at 1040 °C for 20 min using the different composite interlayers, Cu-foam-graphene, Cu-foam-LiAlSiO4, or Cu-foam-graphene-LiAlSiO4, with shear strengths of 122, 147, and 235 MPa, respectively. Particularly, the Cu-foam-graphene-LiAlSiO4 brazed joint demonstrates the highest shear strength. Furthermore, the dispersion of LiAlSiO4 in the joint reduces the coefficients of thermal expansion of difference between the brazing materials and ceramics, as well as the residual stress in the joint. Moreover, the synergistic effect of the solid-solution phase, Zr(s, s), with excellent plastic deformation, and enhanced Zr(Cr, Fe)2 phase further improves the strength and plasticity of the joint.

Computational prediction of surface-tension flow mechanism of molten filler in a V-shaped groove geometry in the brazing process of a heat exchanger

When the temperature rises during the brazing process, only the brazing material melts because of its low melting point. Several analytical approaches have been used to describe filler flow in channels and the progression of erosion grooves. However, only a few studies have examined filler-flow behavior in microgrooves during brazing. In this study, a computational model was constructed to examine the flow in microgrooves on an extruded material’s surface. The capillary flow of the aluminum brazing material was numerically analyzed to investigate the physical properties and surface behavior. Specifically, the surface-tension flow behavior was analyzed by simulating various cross-sectional shapes of the channel grooves and various contact angles of the filler. The effects of various parameters, such as viscosity and boundary conditions, on the filler flow were also analyzed. When the cross-sectional area of the channel groove increases, the filler-flow velocity increases, and the rate of unsteady fluctuation increases with the increasing filler tip velocity. The driving force of the filler flow in the channel groove is considered to be (1) the surface tension, which is based on the filler free-surface curvature, or (2) the dynamic change in the shape of the meniscus, which can be unsteady and induced by Rayleigh–Taylor instability. As the cross-sectional area of the channel groove increases, the capillary force based on the dynamic change in meniscus shape dominates the unsteady change in filler tip velocity, rather than the surface tension based on the filler free-surface curvature formed in the groove.

Study on effects of ultrasound on microstructure refinement at semi-solid statement of ultrasonic-assisted brazing SiCp/Al composites

Ultrasonic composite brazing uses ultrasonic cavitation and acoustic flow effects to ameliorate the soakage property of SiC particles and brazing material, enabling flux-free brazing of SiCp/Al-MMCs under atmospheric conditions. However, its mechanical properties are limited by the performance of the brazing material, which is often difficult to apply in structures with high strength requirements. In order to break through the limitations of conventional ultrasonic composite brazing of SiCp/Al-MMCs, this paper uses 50 vol.% SiCp/Al MMCs as base material and Zn-16Al brazing material. It applies secondary ultrasound at different times during the solidification of the liquid brazing material to reduce the weld grain size and reinforce the weld intensity by using ultrasonic cavitation and acoustic flow effects. The results show that the addition of secondary ultrasound can reduce the α-Al size and make the SiC particles and α-Al evenly distributed in the joint, which can significantly reinforce the intensity of the weld. The shear performance enhanced with the increase of supersound application second, but too long secondary sonication caused atomization of the brazing material, resulting in unfilled brazing material in the weld, which seriously affected the properties of the weld.

Insert Molding of Aluminum Alloy A7075 and Alumina Plate by Semi-Solid Forging

Industrial, electric railway, and automotive applications of inverters and converters use case-type semiconductor packages called power modules. Power modules have multiple joint points, and among them, from the viewpoint of reliability and bonding strength, many studies on metal-ceramic substrate bonding have been reported. Alumina Al203 or aluminum nitride AIN are mainly used for ceramics, and copper or aluminum are mainly used for metals, although alumina and aluminum have a price advantage. The joining methods are generally brazing and AMB (Active Metal Brazing), but there is a need to improve the joint strength, heat dissipation characteristics, and productivity, i.e., a joining method that does not use brazing material. The purpose of this study is to achieve direct joining of alumina A1203 and aluminum alloy A7075, and semi-solid forging [1, 2, 3, 4, 5, 6] was used as the method. The A7075 used in this study is considered to be suitable for this application because of its high strength and thermal conductivity among aluminum alloys. In this study, solid phase ratio 30 % semi-solid forging was actually performed using a servo press and a die, and the results were evaluated by observing the cross section of the fabricated specimens. The punches and dies were circular in shape to ensure uniform spreading of the molten material, and carbon steel S50C with high thermal conductivity was used to quickly dissipate the heat of the semi-solid slurry during the pressing process. The thickness of 99.6 % Al2O3 alumina plate was 2.5 mm. The semi-automatic stirring device was modified to stir the molten metal by attaching a 1000 mm round bar to the rotating part of a tabletop drilling machine and attaching a stirring blade to the tip of the bar. Debonding between aluminum alloy and alumina plate was not confirmed. There was no gap between the aluminum alloy and the ceramic plate.

Clean and efficient recovery of In–Sn and In–Sn–Bi lead-free brazing materials by vacuum volatilization and thermodynamic modeling

In this study, a novel method was proposed for the clean and efficient recovery of high-value-added In–Sn and In–Sn–Bi alloys. Vacuum volatilization of the In–Sn binary alloy was conducted in a temperature range of 1373–1573 K with a system pressure of 5 Pa. The results showed that In and Sn were effectively separated. The Sn content in the residue was 99.9908%, and the In content in the volatile fraction reached 99.66%. Vacuum volatilization of the In–Sn–Bi ternary alloy was conducted out at 1073–1373 K and 5 Pa. The results showed that Bi could be separated from In and Sn, the Bi content in the residue decreased from 32.5% to 3.88%, and the Bi content in the volatile fraction reached 95.67%. The residual In–Sn alloy could be effectively separated by vacuum volatilization. The MIVM, M-MIVM, Wilson equation and NRTL were used to calculate and analyze the activity and activity coefficients of In–Sn, In–Bi, Sn–Bi and In–Sn–Bi alloy elements, respectively, and the results showed that M-MIVM had the highest prediction accuracy. The vapor-liquid equilibrium (VLE) data of the In–Sn, In–Bi, Sn–Bi, and In–Sn–Bi alloys were predicted, and the corresponding VLE phase diagrams were plotted based on the M-MIVM and VLE theory. The predicted VLE values were in good agreement with the corresponding experimental data determined in this study, indicating that the M-MIVM was reliable for indium-based alloys. The results of this work provided reliable experimental data and a thermodynamic model for the VLE study of In-based alloys, opening a new technique for the clean and efficient recycling of binary and multicomponent In-based alloys.

Enhancing Wettability of Cu3P/Cu Systems through Doping with Si, Sn, and Zr Elements: Insights from First Principles Analysis

Explaining the wetting mechanism of Cu-P brazing materials and Cu remains challenging. This fundamental research aims to reveal the wettability mechanism of Si, Sn, and Zr doping on the interfacial bond strength of the Cu3P/Cu system through the first principles study. We carried out several sets of calculations to test the validity of the result; included in the work are those used to establish the interfacial structure and to analyze the effect of doping on the wettability. Specific analysis was carried out in terms of three aspects: the work of adhesion (Wad), the charge density difference, and the density of states (DOS). The calculated results show that doping with Si, Sn, and Zr elements can effectively improve the wettability within the CuP/Cu interface with very high accuracy, and is particularly effective when doped with Zr. These results provide an insightful theoretical guide for enhancing the CuP/Cu system's wettability by adding active elements.

Manufacturing and testing of flat-type divertor mockup with advanced materials

During reactor operation, the divertor must withstand unprecedented simultaneous high heat fluxes and high-energy neutron irradiation. The extremely severe service environment of the divertor imposes a huge challenge to the bonding quality of divertor joints, i.e., the joints must withstand thermal, mechanical and neutron loads, as well as cyclic mode of operation. In this paper, potassium-doped tungsten (KW) is selected as the plasma facing material (PFM), oxygen-free copper (OFC) as the interlayer, oxide dispersion strengthened copper (ODS-Cu) alloy as the heat sink material, and reduced activation ferritic/martensitic (RAFM) steel as the structural material. In this study, a vacuum brazing technology is proposed and optimized to bond Cu and ODS-Cu alloy with the silver-free brazing material CuSnTi. The most appropriate brazing parameters are a brazing temperature of 940 °C and a holding time of 15 min. High-quality bonding interfaces have been successfully obtained by vacuum brazing technology, and the average shear strength of the as-obtained KW/Cu and ODS-Cu alloy joints is ∼268 MPa. And a fabrication route for manufacturing the flat-type divertor target based on brazing technology is set. For evaluating the reliability of the fabrication technologies under the reactor relevant condition, the high heat flux test at 20 MW/m2 for the as-manufactured flat-type KW/Cu/ODS-Cu/RAFM mockup is carried out by using the Electron-beam Material testing Scenario (EMS-60) with water cooling. This paper reports the improved vacuum brazing technology to connect Cu to ODS-Cu alloy and summarizes the production route, high heat flux (HHF) test, the pre and post non-destructive examination, and the surface results of the flat-type KW/Cu/ODS-Cu/RAFM mockup after the HHF test. The test results demonstrate that the mockup manufactured according to the fabrication route still have structural and interfacial integrity under cyclic high heat loads.

A Review on the Friction Stir Brazing for Joining Dissimilar Materials

Friction stir brazing (FSB) is a new technology developed for its ability to join similar and dissimilar metals and alloys resulting in a joint with considerable characteristics through the use of interlayer (braze) material under the action of a pinless rotating tool and other FSB parameters. The frictional heat during FSB is responsible for the melting of the braze material between the two workpieces, while the shoulder action must be satisfactory for the extrusion of the excess braze liquid phase depending on the FSB parameters used. The parameters of FSB also have a considerable impact on the microstructure and mechanical characteristics of friction stir brazed (FSBed) joints. Sound interfacial bonding can be observed in the central zone of FSBed joints, where intermetallic compounds (IMCs) can be formed by direct diffusion among the dissimilar workpieces after extrusion of liquid phase rather than by mechanical mixing or solidification of braze material. Increasing the transverse speed at a constant rotational speed has an influence on the peak temperature, but it remarkably reduces the holding time owing to the increased cooling rate. The use of vibration in the FSB increments the fluidity of the molten braze material among the joining workpieces resulting in a more homogeneous distribution of IMCs particles. In this review article, FSB parameters, bonding mechanisms, as well as the microstructure, and mechanical properties of FSBed joints are reviewed.

Titanium and Tantalum Used as Functional Gradient Interlayer to Join Tungsten and Eurofer97

For the DEMO reactor, tungsten is considered as an armor material. Eurofer97 is planned to be used as a structural material for the first wall and in the divertor region, especially for the shielding liner component. To date, several joining solutions between W and Eurofer97 have been developed (copper brazing, W and Eurofer97 functional gradient material (FGM), etc.). Each existing joining solution has its own advantages (joining material, improved manufacturing process). In the present study, the choice of the joining material is driven, among other constraints, by a desire to minimize the thermal stresses at the materials’ interface. In this regard, FGM represents a promising solution. Another constraint that is taken into account in this study concerns the manufacturing process involved, which should be an improved industrial process. The present study proposes a joining solution, based on FGM, which, additionally to the advantages of the existing solutions, could reduce the long-term activation of the joining material. The development of a joining solution via Ti and Ta as materials constituting the FGM (Ti/Ta FGM) is presented in this paper. Due to the achieved density and the composition’s accuracy, the cold spray process is shown to be adapted for the Ti/Ta FGM’s manufacturing. Based on the feedback on the experience of joining between W, W/Cu FGM and CuCrZr, the final joining between W, Ti/Ta FGM and Eurofer97 is achieved using hot isostatic pressing, followed by a thermal treatment to recover Eurofer97’s mechanical properties, resulting in good joining quality.

Co segregation on WC grain formed in an interfacial reaction between WC–Co cemented carbide and Ag–Cu eutectic brazing material

The interfacial structure between Cu and WC–Co cemented carbide after Ag–Cu vacuum brazing was evaluated. No Co was present on the surface of the WC grains before brazing. The vacuum-brazed specimen was heated at 850 °C for 0.5 h, and Ag and Cu were found to penetrate the grain boundary phase, which initially consisted of Co, over a distance of about 1 μm from the surface of the WC–Co cemented carbide. A Co-containing segregated layer with a thickness of about 2–7 nm formed at both the Cu–rich phase/WC grain interface and the Ag–rich phase/WC grain interface. In addition, a Cu-containing segregated layer with a thickness of about 2 nm formed on the Ag–rich phase side against the Co-containing segregated layer at the Ag–rich phase/WC grain interface. This suggests that the formation of the Co-containing segregated layer originated from the local interfacial reaction between the Co dissolved in molten Ag–Cu phase and the WC grains during brazing.

Microstructure and properties analysis of the brazing alloy prepared from recycled E-waste.

In order to realize the efficient and comprehensive utilization of e-waste resources and short process preparation of alloy brazing materials, this study has analyzed the microstructure and properties of e-waste recycled brazing alloys by the analysis methods of inductively coupled plasma emission spectrometer, differential scanning calorimeter, scanning electron microscope, metalloscope, X-ray diffractometer, micro-hardness tester. Experimental results showed that phase compositions are significant differences between the alloys prepared by the recycled e-waste and the pure metals. The circuit board recycling alloy mainly consisted of α-Fe dendrites, (Cu, Sn) phases, Sn-rich phases and Cu matrix, while the alloy obtained by pure metals is composed of (Cu, Sn) phase, Sn-rich phase and Cu matrix. The melting temperature of alloy obtained by melting the circuit board is in the range of 985.3°C–1,053.0°C, which was wider and higher than that of alloy obtained by pure metal smelting. The shear strengths of the joints brazed by the brazing alloys prepared by the recycle e-waste and pure metals are 182.21 MPa and 277.02 MPa, respectively. There is little difference in hardness between the two types of brazed joints. In addition, there are a large number of precipitated phases in alloy obtained by the recycled circuit board, owing to the precipitation strengthening mechanism. The main strengthening mechanism of alloy obtained by pure metals is solid-solution strengthening. The paper focused primarily on alloy obtained by melting the circuit board and studying the specific composition, melting temperature, structure, and properties of alloys formed by melting the circuit board and pure metals. Meawhile, the size, morphology and other microstructure evolution of the second phase of brazing alloy were investigated to provide theoretical guidance for the brazing alloy in the subsequent actual production process.

Laser-based droplet brazing – Influence of additionally induced thermal energy on joint quality

The demand for semiconductors and microelectronic components is greater than ever and will continuously rise in the future due to increasing automation and digitalization. Also, there is a growing need for robust, high-temperature resistant electrical connections which are essential for the circuit function. Previous investigations have shown that laser-based droplet brazing can create high temperature stable joints e.g. on thin silver layers, without applying an external force on the micro-component to be joined. In order to expand the application field of this process, further combinations of different brazing and substrate materials are investigated. In this paper the influence of additionally induced thermal energy at the diffusion zone was analyzed via shear tests. The studies show, that using brazing alloy CuSn11 in combination with a substrate heating provides the most robust joints on the tested substrate material.

Adding Hf element to improve the strength and wear resistance of diamond brazed with Ni-based boron-free brazing filler metal

Nickel-based filler is a very important brazing material with excellent corrosion resistance and strong hardness. However, its high-temperature thermal damage, graphitization and multiple brittle phases are still problems to be solved. In this work, the NiCrSiCuSn boron-free brazing filler metal is reinforced by adding different contents of Hf element. The microstructure of the filler and morphology of the diamond were analyzed by scanning electron microscope and energy dispersive spectroscopy. The phase composition of the brazed joint is characterized by X-ray diffraction. The alloy segments and brazed diamond segments were performed by the vickers microhardness tester and the friction and wear tester, respectively. The results show that when 1 wt% Hf is added to Ni-based boron-free filler, the melting point of the filler is the lowest and the crystal grains are also refined. At the same time, chromium carbide is formed between diamond and brazing material, so they are closely connected. Compared with other components, brazed diamond with 1 wt% Hf brazing filler metal has the best exposure, higher joint strength and wear resistance, and a lower degree of graphitization. The morphology of the bonding surface and the wear surface shows that the addition of 1 wt% Hf reduces the thermal damage of the diamond.In turn, the mechanical properties of the joint are optimized.

Influences of Sn on Properties of Ag-Based and Cu-Based Brazing Filler Metals

Ag-based and Cu-based brazing filler metals, which are the most widely used brazing materials in industrial manufacturing, have excellent gap-filling properties and can braze almost all the metallic materials and their alloys, except for the low-melting-point metals such as Al and Mg. Therefore, Ag-based and Cu-based brazing filler metals have attracted great attention. In this review, three series of typical Ag-based filler metals: the Ag-Cu, Ag-Cu-Zn, and Ag-Cu-Zn-Sn alloys; and three series of Cu-based filler metals: the crystalline and amorphous Cu-P filler metals, as well as the Cu-Zn filler metals, were chosen as the representatives. The latest research progress on Sn-containing Ag-based and Cu-based brazing filler metals is summarized, and the influences of Sn on the melting characteristics, wettability, microstructure, and mechanical properties of the selected filler metals are analyzed. Based on these, the problems and corresponding solutions in the investigation and application of the Sn-containing Ag-based and Cu-based filler metals are put forward, and the research and development trends of these filler metals are proposed.

A systematic study on the effect of coating type and surface preparation on the wettability of Si-Bronze brazing filler material on GI and GA-coated DP600

Zn-coated advanced high strength steels are popular in the automotive industry due to their excellent combination of mechanical strength and ductility as well as superior corrosion resistance provided by the Zn-coating – with hot-dip galvanized and galvannealed coatings being the most popular. Gas metal arc brazing technology is a non-fusion joining method, proposed as an alternative to the gas metal arc welding process due to several advantages: The arc-brazing process delivers significantly lower heat input to the substrate, which minimizes the Zn-coating burn-off leading to higher corrosion protection for the joined parts, and reduces the HAZ softening phenomenon which affects the mechanical integrity of the substrate, while at the same time reduces welding defects such as porosity and blowholes. The strength of an arc-brazed joint depends on the spreading of the molten filler material over the joint to create a bond between the parts as the molten braze solidifies. Existing literature on the subject suggests that heat input is the main driving factor controlling the wettability of the molten braze material with the type of shielding gas used also having an effect. However, the influence of different types of Zn-coatings and their respective surface condition (i.e., clean, or unclean) on the wettability of Cu-based molten braze materials during arc-brazing has not been investigated. The present work investigates the effect of surface morphology of galvanized and galvannealed DP600 steel in the as-received and plasma cleaned conditions on the wettability of molten Si-Bronze (CuSi3Mn1) brazing filler material in the bead-on-plate configuration. The findings of this work clearly demonstrate that the type of coating and its surface condition has a significant effect on the spreading of the molten filler material and on the growth of the intermetallic compound layer at the joint interface and therefore, should be taken into consideration as a factor that can impact the efficacy of an arc-brazed joint. • Evaluating surface morphology of different Zn-coatings to calculate their surface free energy. • Establishing a clear link between the surface roughness of Zn-coated steels on the wettability of molten Si-Bronze filler material. • The study shows that the wettability of the molten filler material is also affected by the presence of organic contaminants on the coating surface. • This work shows the relevance of surface morphology in controlling the wetting length of weld brazed joints. • The thickness of the intermetallic compound layer at the braze interface can be controlled by using oxygen plasma cleaning.