Wear Resistance Characteristics Research Articles

Evaluation of wear resistance and microstructural properties of laser cladded martensitic and austenitic stainless steel

A promising technology for improving the wear resistance of certain metallic components is laser cladding. This study assessed the martensitic and austenitic stainless steels with laser cladding for wear resistance and microstructural characteristics. Martensitic stainless steel (AISI 420) and austenitic stainless steel (AISI 304L) were both employed in this investigation. A cobalt alloy containing powdered iron, chromium, and other elements was laser clad onto both materials. Then, to assess the surface topographical characteristics of the coatings, atomic force microscopy was employed. The findings demonstrated that, in comparison to the austenitic stainless steel coating, the martensitic stainless steel coating displayed a greater wear resistance. Additionally, the coatings had various surface topographies, with martensitic stainless steel being the most evident from the results of the atomic force microscopy. When compared to substrates without coatings, it has been found that laser claddings provide substrates with higher elongation to fracture.

Study on mechanical and micro-structural properties of aluminium matrix composite reinforced with graphite and granite fillers

Composites are gaining increasing popularity nowadays due to their wide range of applications and flexible design options. Aluminium Matrix Composites (AMCs) have garnered increasing attention in contemporary times as a subject of research. The inclusion of reinforcements in the metallic matrix results in improved stiffness, specific strength, wear resistance, creep resistance, and fatigue characteristics when compared to conventional engineering materials. In our study, we are employing a 6061 grade Aluminium alloy as the fundamental material, and augmenting it with Synthetic Graphite and Granite fine particles as strengthening agents. The Aluminium matrix composite is produced through the incorporation of synthetic graphite particles and granite dust into the molten aluminium via a Stir Casting Furnace utilising a bottom pouring technique at temperatures within the range of 850 to 950 °C. The Aluminium Metal Matrix composite samples is fabricated with varying reinforcement percentages relative to the base material. The distribution of particles within the Aluminium Matrix is analysed. Furthermore, the fabricated composites have undergone Tensile, Impact, Shear, and Micro hardness tests to assess the effects of incorporating reinforcements. All examinations conform to the standards set by ASTM. A comparative analysis is conducted between the mechanical properties exhibited by the original Aluminium alloy and the Aluminium metal matrix composites that have been manufactured.

Friction Characteristics of SUS440C/Si3N4 Lubricated by Polytetrafluoroethylene Under Cryogenic Environment

Abstract The friction characteristics of SUS440C-Si3N4 lubricated by polytetrafluoroethylene (PTFE) under cryogenic environment have not been researched well. The lubrication mechanisms in such friction condition need to be clarified to improve the fidelity of performance modeling for ball bearings used in liquid rocket engine turbopumps. This research experimentally investigated the friction coefficient of bearing materials via PTFE lubrication under cryogenic environment to clarify the friction characteristics of cryogenic turbopump ball bearings. These experiments revealed the dependence of the contact pressure on the friction coefficient. By several analyses, it was found that lower friction and better wear-resistance characteristics were caused by PTFE film that strongly adhered to metal fluoride formed on the surface of SUS440C due to moderate friction energy.

Tribological considerations for failure restoration and maintenance of radial plunger pump against friction and abrasive wear behavior by microwave cladding of Ni-Graphene

Clean and efficient manufacturing techniques are in great demand in modern industrial facilities. New methods are being developed which are cleaner, environment-friendly, economical, and have better mechanical properties, among others. Due to hot corrosion, Tribological components are often subjected to wear and tear. Graphene (Gr) is a promising material with microwave absorption performance due to its self-lubricating properties, low density, and cementite (Fe3C) formation capabilities with iron. This work examined the effect of self-lubricating behavior and surface hardening of plungers of Austenite alloy by Ni-Gr cladding and glazing. Using silicon carbide abrasive media, a pin-on-disc wear tester was utilized for abrasion testing. Scanning Electron Microscopy (SEM), and X-ray diffraction (XRD) analysis supplemented with a microhardness test were performed to measure the improvement in the properties of clad samples. The results showed that temperature variation influences phase change and mechanical properties. The Ni-Gr cladding showed dense eutectic microstructure at 750° C. XRD’s results revealed that the disintegration of the cladding layer is reduced due to heat treatment along with the generation of the Fe3C phase. In addition, the deposited specimen confirmations maximum wear resistance and hardness characteristics with a minimum wear rate at 750 °C, just above the steel's first critical temperature.

State of art: Review on laser surface hardening of alloy metals

Surface hardening treatments are performed to increase the hardness, wear resistance, durability and their micro structural properties. After the development of High-Powered Diode Lasers (HPDL), the laser surface hardening process is widely applied due to their non-contact treatment process, rapid cooling without any medium, controlled method of heat treatment and depth with automation and precision with relatively minimum energy input. Laser surface hardening of steels, carbon alloys, iron and other metals in manufacturing of components, stamping and forging dies, tools and other components in the field of mechanical, automotive and metallurgical have shown a positive progression in hardness and wear resistance with controlled phase changes. The factors of laser power density and travel speed plays key roles in phase changes and the surface transformation hardening. The surface hardening of heavily loaded components under motion should possess good surface roughness, tribological characteristics of wear resistance, hardness and temperature coefficients. Thus, laser surface hardening is optimum, controlled and economic way of surface treatment processes in manufacturing of mechanical components.

Synthesis of Multicomponent Coatings by Electrospark Alloying with Powder Materials

The results of systematic studies of the electrospark alloying process with the introduction of dispersed materials into plasma of low-voltage pulsed discharges are presented. Technological methods have been developed for supplying the powder material straight into the treatment zone through a hollow electrode of an anode or from the side, with the electrode-anode periodically contacting the substrate of cathode. It has been established that under the same energy regimes, when powder materials were introduced into the discharge zone, the increase in the mass of the cathode per time unit increases from 10 to 15 times or more. This study presents the process of synthesis of carbide phases (TiC and WC) during electrospark alloying of steel substrates with electrodes made of Ti, W, and graphite, with additional supply powders of these materials into the processing zone. A process has been developed for the synthesis of ternary compounds, so-called MAX-phases: Ti2AlC, Ti2AlN and Ti3SiC2 by electrospark alloying with powder compositions TiAlC, TiAlN and TiSiC. These MAX phases exhibit a unique combination of properties that are characteristic of both metals and ceramics. Energy modes of the processing were optimized, which resulted in high-quality coatings with the maximum content of carbide phases and ternary compounds. It has been established that the energy of electrical pulses during electrospark alloying, when powders of materials are fed into the interelectrode gap, ranges from 0.8 to 3.0 J, depending on their thermal physical properties. High wear and corrosion resistant characteristics of C45 structural steel with such electrospark coatings are obtained. The wear of steel with coatings in comparison with uncoated steel decreased by an average of 5.5–6.0 times. It was estimated the high corrosion resistance of 40X13 steel coated with TiC and WC in 3% NaCl solution. The corrosion current for these coatings is 0.044 and 0.075 A/cm2, respectively, and is significantly less than for coatings made of TiAlC, TiAlN, and TiSiC compositions. X-ray phase and optical metallographic microscopy analyses enabled the display of the amorphous-crystalline nature of the coatings.

Increasing the Wear Resistance of Restored Car Parts by Using Electrospark Coatings

The work scientifically substantiates the application of effective technology for the restoration of worn car parts by applying new electrospark coatings based on electroerosion nanomaterials. The developed technology is characterized by technological flexibility, cheapness, simplicity, does not require the use of expensive and scarce materials and equipment, and also meets the requirements of environmental safety. The proposed technology can be used to restore a wide range of parts for cars, tractors and other machines. Experimentally established dependences of the effect of the properties of electroerosive materials on the properties of electrospark coatings of restored car parts. It is shown that the content of nano-sized particles in the electrode material contributes to the improvement of the physical and mechanical properties of electrospark coatings. The dependences of the influence of the properties of electrospark coatings on the resource of restored car parts were experimentally established. It is shown that the resource of the shafts of turbocompressors restored according to the recommended technology is higher than the resource of new shafts by an average of 1.5 times. Experimentally established rational modes of applying wear-resistant coatings to worn shafts of turbocompressors, which provide the necessary complex of physical and mechanical properties of the coating and the given resource of the shafts as a whole (rotation frequency of the part, min - 1 - 50; electrode feed, mm/min - 0.4 ... 0.5). The characteristics of wear resistance of electrospark coatings of turbocompressor shafts, obtained using electroerosion nanomaterials, were studied. It is shown that the average value of the coefficient of friction of the electrospark coating was 0.146 instead of 0.486 without coating, which is 3.3 times lower. According to the results of production tests, it was found that the duration of operation of the turbocharger, with the restored method of electrospark treatment with a nanostructured electrode shaft, increased by 2.1 times compared to a new industrially manufactured shaft. Thus, when abrasive material containing a fraction of 0.1...0.4 mm was introduced, the operating time of the turbocompressor with a restored shaft was 12.8 hours, and the operating time of the turbocompressor with a new shaft without wear of the nominal size was 8.1 hours.

Wear resistance of structural steels nitrided in a cyclically switched discharge with dry friction

The paper examines the method of conducting tribological studies in the dry mode of friction of nitrided and unhardened structural steels 20 and 45 in order to achieve comparable results of laboratory tests with operational characteristics. Preliminary studies of anodized steels of the same steels indicate that under conditions of extreme friction it is extremely difficult, and in some cases impossible, to use such values of specific pressure on the friction surface, at which it would be realistic to compare the results obtained for different samples made of different brands materials and processed using various technological processes. Since during the tests, constant lubrication of the friction zone was ensured, a layer of lubricant was present on the friction surface up to a certain pressure value, which led to extremely small indicators of linear wear. However, depending on the characteristics of the modified surface, there was a critical value of pressure at which the layer of lubricant was squeezed out of the friction zone, which led to instant adhesion of the surfaces. Thus, the study of wear resistance in the dry mode of friction ensures a significantly higher productivity of experiments.
 Unlike experiments with limit friction, dry friction can be used for different steels at the same pressure value, which eliminates the problem of comparability of results and contributes to the objectivity of conclusions regarding the effectiveness of various modification processes.
 According to the results of previous experiments, such a compromise pressure value can be 16 MPa.
 Another important phenomenon for the analysis of the influence of the modification results on the wear resistance characteristics of the surface is established - the effect of relaxation processes in the near-surface layers, which have already acquired structural transformations under the influence of pressure in the friction zone.
 For all steels, there is some slowing down of the intensity of wear after a break with a gradual return to the intensity characteristic of a certain brand of steel. The reason for such a phenomenon can only be the relaxation of stresses and the equalization of the characteristics of the structure in the near-surface layers. At the same time, the result is the strengthening of the surface, which explains the decrease in the intensity of the wear process. over time, as the strengthened layer breaks down, the indicators of the surface condition become equal to those before the break and the intensity of wear is restored.

Effect of synovial fluid temperature on wear resistance of different polymer acetabular materials.

In order to investigate the effect of frictional heat on the wear resistance characteristics of polymeric acetabular materials, the tribological tests and wear numerical analysis of three common polymer acetabular materials were carried out under different synovial fluid temperatures. The study results show that XLPE and VE-XLPE exhibit superior wear resistance compared to UHMWPE in high-temperature, heavy load environments. The coefficient of friction of three materials gradually decreases as the temperature of the synovial fluid increases. The wear depth and wear volume of the three materials increased with the increase of the temperature of the synovial fluid, and the forms of wear at 46°C and 55°C were mainly adhesive wear and plastic deformation. The higher temperature of the synovial fluid accelerates the oxidative degradation of the material surface and generates oxidation functional groups, which leads to the breakage of C-C bonds in the surface molecular chains under the sliding shear effect, thus reducing the mechanical properties of the material. Specifically, the surface of the polymer material will soften at a higher ambient temperature, mainly due to the decrease of hardness, and then deteriorate in the friction property, and finally increase the wear rate. Ansys results showed that the volume wear of the three materials increased with the increase of synovial fluid temperature, and the trend could be approximately linear. Numerical calculations predict that VE-XLPE has the highest wear of 0.693mm3 among the three materials at 37°C, followed by XLPE at 0.568mm3 and UHMWPE with the lowest wear of 0.478mm3. At higher synovial fluid temperatures (46°C, 55°C), VE-XLPE still has the largest wear volume among the three materials, while XLPE and UHMWPE have similar wear. The wear cloud pictures showed that the maximum wear volume occurred near the edge of the acetabulum.

Three-Body Abrasive Wear-Resistance Characteristics of a 27Cr-Based 3V-3Mo-3W-3Co Multicomponent White Cast Iron with Different Ti Additions

A multicomponent white cast iron containing 5 wt.% each of Cr, V, Mo, W, and Co (MWCI) is known to have excellent wear-resistance properties due to the precipitation of some very hard carbides, such as MC, M2C, and M7C3. However, it seems possible to improve the wear resistance of MWCI by increasing the carbide volume fraction (CVF). Thus, 27 wt.% Cr based on 3 wt.% each of V, W, Mo, and Co was simultaneously added into the white cast iron. To avoid the tendency of carbides to crack due to high M7C3 precipitation levels, titanium (0–2 wt.% Ti) was also added. A rubber wheel abrasive machine test according to the ASTM G65 standard with two different abrasive particle sizes (average: 75 and 300 μm) was used to evaluate the wear characteristics of the alloy. The results show that the wear resistance of these new alloys (0Ti, 1Ti, and 2Ti) is lower than that of MWCI in small silica sand, owing to the lower hardness. However, a different condition is present in large silica sand, for which the abrasive wear resistance of MWCI is lower than that of the 0Ti and 1Ti specimens. In addition, TiC precipitation effectively refined the size of M7C3 carbides and reduced their cracking tendency. Thus, the wear resistance of 1Ti is comparable to that of 0Ti, although it has a lower hardness factor. However, the wear resistance of the alloy significantly decreased following the addition of Ti by more than 1 wt.% due to the lower hardness and CVF. Therefore, it can be said that the abrasive wear characteristics of the alloy are not only affected by the hardness, but also by the micro-structural constituents (type, size, and volume fraction of carbides) and silica sand size.

Расчёт и выбор посадки с зазором с использованием теории гидродинамической смазки

Hydrodynamic lubrication increases the service life of connections. The quality and durability of connections with hydrodynamic lubrication is determined by functional parameters, including the characteristics of strength, rigidity, wear resistance and accuracy characteristics. In these joints, the accuracy characteristics are gaps, surface roughness of parts, shape deviation and surface arrangement. To ensure the largest supply of materials and parts and the greatest resource, the authors calculated a fit and selected for connecting the plain bearing of the gearbox of the grain drying screw conveyor operating under hydrodynamic friction. For this connection, two fits were chosen by calculation: Ø50H9/g9 and Ø50H7/g6. Based on the rational assignment of the surface roughness of rubbing pairs, it is necessary to assign a fit Ø50H7/g6, which has an accuracy factor of 22. For a fit Ø50H9/g9, the accuracy factor corresponds to 7. The recommended fit Ø50H7/g6 is provided by honing the hole and fine grinding the shaft. It is the fit that provides the largest stock of parts materials for wear and the largest connection resource.

Higher wear-resistant surfacing at high temperatures using a hybrid cladding process

A novel hybrid cladding process is developed to control the mechanical properties of the inner metallic clad layer by combining direct energy deposition (DED) and ultrasonic nanocrystal surface modification (UNSM). The hybrid process allows the manipulation of the cladding layers' internal and external mechanical properties to the desired surface and bulk properties. To verify the usefulness of this method, the wear resistance test of the Inconel-718 cladding layer at high temperatures of 200 and 400 °C was performed, and it was confirmed that the wear resistance was improved to 25.4 % and 14.4 %, respectively. This work analyzes the wear-resistant characteristics with and without UNSM treatment in the DED process. The proposed method is a promising way to change the internal mechanical properties of the cladding layer with high controllability and repeatability.

Friction and wear behavior of fluoride added Si3N4-SiC ceramic composites at elevated temperature

The addition of fluoride phases often provides promising wear resistance characteristics in ceramic matrix composites at elevated temperatures. In this work, MgF2 added Si3N4–SiC nanowire composite is successfully fabricated to enhance wear resistance capabilities at 500OC. Tribological characteristics of Si3N4–SiC composite with the addition of fluoride phase are reported here. The composite matrix with 5 wt.% MgF2 shows a significant decrease in coefficient of friction by ∼25.40% and an improvement of specific wear rate by ∼78.35%, by providing a tribo layer at the mating interfaces. Moreover, the composite can achieve a high fracture toughness of ∼10.56 MPa.m0.5 with the addition of SiC nanowires. However, the addition of a higher amount of (>5 wt.%) fluoride diminishes the mechanical properties of the ceramic composite. This leads to a change of wear mechanism from delamination to abrasion, causing a higher wear rate.

Эксплуатационные характеристики ниток из различных синтетических материалов в орудиях рыболовства и сооружениях аквакультуры

Twisted threads made of polyethylene and nylon, different in diameter and manufacturer, were studied, the dependences of wear on various layouts were revealed. The given experimental data and the obtained formulas make it possible to carry out a clear calculation for the selection of the appropriate diameter and structure of polyethylene threads when replacing nylon threads. It also shows an approach to the principles of the layout of polyethylene threads for the production of knotted parts with maximum strength and wear-resistant characteristics.

Synthesis, characterization and cutting performances of gradient gradual changing (GGC-) MCD/SMCD/NCD/UNCD diamond coatings with tailored interfacial integrity on CFRP drilling tools

Drilling holes is a common mechanical processing method in the high-precision machining of carbon fiber reinforced plastic (CFRP) material. Diamond coatings can be deposited on the drilling tools to enhance the tool life and improve the machining quality. However, traditional multilayer diamond coatings, such as MCD/NCD etc., easily suffer from interfacial separation in actual applications due to the sharp interfaces of diamond layers. Novel gradient gradual changing (GGC-) structure without clear interfaces is applied to tailor the architecture of diamond coatings, which can lead to superior interfacial integrity and the reduction of sp2 phase content at the transition between distinct diamond layers. Various diamond films, containing monolayer diamond films (MCD, SMCD, NCD, UNCD) and gradient gradual changing multilayer diamond films (GGC-MCD/SMCD/NCD, GGC-MCD/SMCD/NCD/UNCD), were fabricated on WC-Co samples. The deposition of tailored gradient gradual changing coating interfacial architecture can be accomplished by controlling the linear variation of carbon concentration and gas pressure simultaneously. The complementary characteristics of high coating-substrate adhesive strength, superior frictional and wear resistance, good interfacial integrity and favorable crack propagation resistance are concentrated on GGC-MCD/SMCD/NCD and GGC-MCD/SMCD/NCD/UNCD coatings compared to monolayer MCD, SMCD, NCD and UNCD coatings. Moreover, because of the existence of UNCD layer, GGC-MCD/SMCD/NCD/UNCD coating performs lower surface roughness, frictional coefficient and higher surface smoothness than GGC-MCD/SMCD/NCD coating. Besides, the cutting performances in high-speed drilling experiments of CFRP laminates using different types of diamond coated drilling tools were compared systematically, showing that the dominant wear modes are abrasive wear and adhesive wear, and the GGC-MCD/SMCD/NCD/UNCD coated drilling tool exhibits the longest tool lifetime and best machining quality because of the overall interfacial integrity and high surface smoothness.

Atomic Cross-Talk at the Interface: Enhanced Lubricity and Wear and Corrosion Resistance in Sub 2 nm Hybrid Overcoats via Strengthened Interface Chemistry.

Friction, wear, and corrosion remain the major causes of premature failure of diverse systems including hard-disk drives (HDDs). To enhance the areal density of HDDs beyond 1 Tb/in2, the necessary low friction and high wear and corrosion resistance characteristics with sub 2 nm overcoats remain unachievable. Here we demonstrate that atom cross-talk not only manipulates the interface chemistry but also strengthens the tribological and corrosion properties of sub 2 nm overcoats. High-affinity (HA) atomically thin (∼0.4 nm) interlayers (ATIs, XHA), namely Ti, Si, and SiNx, are sandwiched between the hard-disk media and 1.5 nm thick carbon (C) overlayer to develop interface-enhanced sub 2 nm hybrid overcoats that consistently outperform a thicker conventional commercial overcoat (≥2.7 nm), with the C/SiNx bilayer overcoat bettering all other <2 nm thick overcoats. These hybrid overcoats can enable the development of futuristic 2-4 Tb/in2 areal density HDDs and can transform various moving-mechanical-system based technologies.

Effect of the Binder during Ultra-Precision Polishing of Tungsten Carbide Using a Semirigid Bonnet Tool.

Tungsten carbide (WC) has the characteristics of high hardness, high strength, corrosion resistance, wear resistance and excellent fracture toughness. Accordingly, it has been commonly used as the material for cutting tools and molds in glass-forming techniques. To obtain ultra-smooth surfaces, fine polishing of WC is indispensable. However, the efficiency of WC polishing is low using the existing polishing methods, and the mechanism behind the polishing process requires further investigation. Specifically, the effect of the binder in WC polishing is not clear since there are different kinds of WC with various weight percentages of the binder. In this paper, we present the findings of a study on the polishing performance of two kinds of WC material, with and without the binder, using a semi-rigid (SR) bonnet polishing tool. A series of experiments were performed on a 6-DOF robotic polishing instrument to investigate the material-removal characteristics, surface integrity and sub-surface damage after polishing. The results demonstrate that the SR bonnet polishing tool successfully reduced the surface roughness of WC with and without the binder to the nanometric level, though the lowest surface roughness was obtained on binder-less WC. No obvious sub-surface damage was observed under SEM inspection, while the processing efficiency was greatly improved owing to the high material removal rate of the tool. Based on our analysis of key polishing parameters and corresponding surface integrities, the effect of the binder on the polishing performance is explained, which offers excellent guidance for WC polishing.

A new hybrid suspension and solution precursor thermal spray for wear-resistant silicon carbide composite coatings

Silicon Carbide (SiC) coatings offer exceptional wear resistance and excellent tribological characteristics; however, it is a challenging material to be thermally sprayed due to a lack of melting point. In this study, a hybrid, single-step suspension and solution precursor feedstock design is proposed, consisting of a SiC suspension modified with Yttrium Aluminium Garnet (YAG) precursors, for thermal spraying of SiC/YAG coatings. The decomposition of SiC was restricted in all spray campaigns. The solid loading of SiC (from 10 wt% to 20 wt%) and YAG phase (from 20 wt% and up to 50 wt%) were varied in an attempt to improve wear performance, enhance coating cohesion, and minimise porosity of the studied coatings. Among all studied coatings, 60 wt% SiC/40 wt% YAG and 50 wt% SiC/50 wt% YAG coatings at a 10 wt% solid loading were the best-performing coatings, demonstrating a promising wear resistance up to a sliding distance up of 1000 m, a dense coating structure with porosity at 0.4 ± 0.2%. The feedstock design opens up a new method to process materials which are difficult, if not impossible, to process using a conventional thermal route.

Wear resistance characteristics of micro-sized ceramic beads in a vertical bead mill

To investigate the wear resistance characteristics of micro-sized ceramic beads, wear tests reflecting real milling conditions were performed on yttrium-stabilized zirconia beads with diameters of approximately 100 μm. And a novel method for monitoring of wear state is proposed to obtain the wear rate of micro-sized beads using the change in size of beads with time. A vertical bead mill was employed to simulate the milling environment of the beads. The size change of the ceramic beads as a function of milling time was monitored using a particle size analyzer and plotted to determine their wear rate. The wear rate of each ceramic bead was derived from the slope obtained through linear regression analysis: 0.0215 μm/h, 0.0058 μm/h, and 0.0075 μm/h for Beads #1, #2, and #3, respectively. The Vickers hardness, phase fraction, and grain size of the ceramic beads were analyzed and compared to find out the cause of the difference in the wear rate. Vickers hardness was measured in the central, intermediate, and outer regions of the cross-sections of the ceramic beads. The wear rate of the ceramic beads was largely dependent on the hardness of the outer region, rather than those of the central and intermediate regions. Bead #2, which had the lowest wear rate, exhibited the highest hardness of 1371 HV (measured in the outer region). Bead #2 had more tetragonal phase and smaller grain sizes than those of Beads #1 and #3.

New Frontiers in Electrodeposition for More Sustainable Electroplating Processes

Although technological and processing advancements occurred in the past forty years, industrial firms are still struggling to provide solutions to corrosion protection as well as reduction of toxic wastes. Specifically, large-scale industrialization of electroplating techniques will continue to be limited by strict environmental regulations. Moreover, price volatility of the highly demanding electroplated materials like gold, palladium, copper and nickel will heavily impact the market in the next years. In that respect, alloy plating offers better answers in terms of economic growth and environmental sustainability due to fine tuning composition, morphology and crystallinity [1]. The main categories of alloy compounds are presented and the most important properties for the manufacturing process discussed. Particular attention is devoted to advances in industrial quality control and viable solutions for the reduction of precious metal content in electroplated accessories as well as replacement of cyanide and nickel baths with non-toxic compounds, also considering the commercial needs of wear resistance and aesthetic characteristics of gloss.The electrodeposition of Cu-Sn alloys (bronze) has earned considerable interest thanks to the chemical-physical properties of this alloy, which make it a valid substitute for nickel in fashion industry. Generally, most of the bronze coatings are electroplated starting from baths containing cyanides, and the metal precursors are selected as cyanide compounds. Free cyanide is a well-known problem in the galvanic production cycle both in terms of toxicity for the workers as well as for the environment, and in terms of costs associated with its disposal. The aim of this study is to develop an electroplating bath totally cyanide-free, therefore formulated in an innovative way and which, in addition to being free from this dangerous species, has an eco-friendly support electrolyte. To achieve this goal, methanesulfonic acid (MSA) was chosen as electrolyte, which is biodegradable as part of the natural sulfur cycle. We've studied different formulations in terms of metal precursors, organic additives and their concentrations [2-3].The same cyanide issue is present also in for the electrodeposition of silver, for this reason the influence of polyethyleneimine (PEI) as additive for cyanide-free silver bath, in combination with 5,5-dimethylhydantoin (DMH) as complexing agent, was studied [4]. Chronoamperometry was used to investigate the electrodeposition mechanism, which is found to be a three-dimensional diffusion-controlled nucleation and growth mechanism, according to the Scharifker–Mostany’s model. Smoother, brighter and blue colored silver deposits are obtained in the presence of PEI in a Hull’s cell test, at low density current. Eventually, the influence of nitrate anion is also investigated. The presence of nitrate increases the range of current density allowing for an effective Ag deposition.We also investigated the use of modulated currents to increase the throwing power of electroplating, obtaining a more uniform deposition and reducing the amount of metals but maintaining the required characteristics. Pulsed current justifies its practical application mainly through its ability to influence the mechanisms of electrocrystallisation, which in turn control the mechanical and physical properties of the deposited metal. By simply adjusting the amplitude and length of the pulses, it is possible to control not only the composition and thickness, in atomic order, of the deposits, but to improve their characteristics such as grain size, porosity and homogeneity [5].The authors acknowledge Regione Toscana POR CreO FESR 2014-2020 – azione 1.1.5 sub-azione a1 – Bando 1 “Progetti Strategici di ricerca e sviluppo” which made possible the projects “A.C.A.L. 4.0” (CUP 3553.04032020.158000165_1385), “A.M.P.E.R.E.” (CUP 3553.04032020.158000223_1538) and “GoodGalv” (3647.04032020.157000060).