Physical Vapor Deposition Coatings Research Articles

Comparative Analysis over Tribology Characterization of TiAlN and TiAlSiN PVD Coating on Plasma Nitride Alloy 20

The nickel–iron–chromium (alloy 20) is enriching by hybrid surface treatment through plasma nitride (PN) and physical vapor deposition (PVD) process. The plasma nitriding process takes 12 h at 500 °C. Potentiodynamic testing is used to characterize the corrosion performance of the treated material, followed by morphological analysis of the exposed surface; XRD, EDX, SEM, hardness, and tensile testing are used to investigate appropriate coating properties. Plasma nitride and hybrid PVD nickel–iron–chromium alloys exhibit perlite (γ + α′) phases and martensite (γ + α) phases, respectively. The martensite microstructure ensures superior tensile strength and hardness. The pin-on-disc tribometer test proposes to analyze friction and hard-faced behavior in the dry sliding position. The inclusion of Si improves the adherent oxide film, resulting in a low wear rate in TiAlSiN alloy 20. Due to the presence of the passive film, TiAlSiN alloy 20 exposes the most passive region to attain better corrosion resistance.Graphical Abstract

Tribological properties of in-situ PVD TiAlN, TiSiN, and TiAlN/TiSiN coatings under ambient air and vacuum environment

It is known that the interest in manufacturing in a vacuum environment has increased in recent years. Thus, the wear behavior of mechanical tools under vacuum conditions has critical importance. However, adhesion and cold-welding problems between tool and working piece in vacuum conditions lead to poor wear properties and severe coefficient of friction values. Surface treatment methods such as physical vapor deposition coatings can eliminate these undesirable consequences, especially transition metal nitrides. In this study, TiAlN, TiSiN, and TiAlN/TiSiN films were coated on AISI H13 tool steels employing the cathodic arc evaporation technique. Whether the coatings grown to the substrate surface have a positive contribution to the wear performance of the substrate in the ambient air and vacuum environment was answered. Scanning electron microscope, energy dispersive spectrometer, and X-ray diffractometer analyses were used to attain structural properties. The hardness was measured using a nano-hardness tester, and the adhesion properties were determined by a scratch test. The wear behavior of the substrate and coating samples are determined under 2 N constant normal load and using WC-6%Co counter bodies under ambient air and vacuum conditions. The hardness of samples improved owing to surface coatings, and the highest nano-hardness value was determined from the TiSiN coatings as 39.42 GPa, which is ∼700% greater than the substrate. It has been observed that coated samples have superior wear performance in both wear conditions. Besides, it is determined that those tested under a vacuum condition showed superior wear resistance than the samples tested under ambient air. While TiSiN film exhibits the highest wear resistance in ambient air, the TiAlN/TiSiN layer is the best in a vacuum environment. Owing to the deposited coatings, the seizure mechanism between the friction surfaces, which is frequently encountered in the vacuum environment, is prevented, and a fascinating improvement in terms of friction coefficient is achieved.

HIPIMS/UBM PVD Coating Equipment Designed to Coat Universal Sized Broaches

This paper describes a physical vapor deposition (PVD) coating equipment, as well as the according deposition parameters suitable to provide hard nitride coatings on broaches up to a length of 2.2 m. The octagonal-shaped vacuum chamber reached a height of 4.5 m and a diameter of 1.2 m. To explore a sufficient and reproducible film, an adhesion test sample and tools were subjected to a pretreatment in a Cr2+ Ar+ high-power impulse magnetron sputtering (HIPIMS) plasma prior to the actual film deposition. Two deposition methods were applied: reactive unbalanced magnetron (UBM) sputtering was introduced to deposit TiAlN-based coatings from Ti50Al50 2.5 m long targets. Alternatively, multilayer coatings were generated by reactive simultaneous UBM sputtering from Ti50Al50 and TiAl6V4 targets, respectively, and chromium targets utilizing high-power impulse magnetron sputtering (HIPIMS) technology. In the latter case, three cathodes were furnished with 0.9 m long targets lined up upon each other. A segmented UBM cathode design was described to meet economic deposition if varying tool sample lots in the deferring workpiece lengths have to be handled in industrial practice. The resulting (TiAl/Cr)N multilayer coatings attained typical hardness values of HV 2800 and an adhesion measured by critical load up to 50 N. The cutting performance of this coating was evaluated by simulated shaping tests over a test length of 210 m on C 45 steel. The (TiAlV/Cr)N showed an improved wear behavior by factor of 2 to 3 compared to TiN deposited by cathodic arc operated in an industrial PVD coater. A real comparison was undertaken, applied to a 1.3 m long model broach. (TiAl/Cr)N showed a prolongation in industrial lifetime by 150% compared to TiN.

Local Release of Strontium from Sputter-Deposited Coatings at Implants Increases the Strontium-to-Calcium Ratio in Peri-implant Bone.

It is well known that strontium (Sr) has a significant effect on peri-implant bone healing when administered systemically. Due to the risk of adverse effects of such treatments, new routes focusing on the local, sustained release of Sr from bone-implant contact surfaces have been explored, with success in in vivo experiments. However, the increase of Sr concentrations in the peri-implant bone has not been described in depth yet. Here, we show that a local, sustained Sr release from Ti-Sr-O physical vapor deposition (PVD) coatings by magnetron sputter coating increases the Sr/Ca ratio close to the implant in a rabbit model and that the Sr/Ca background level is reached approximately 500 μm from the implant.

Understanding the Tribological Behavior of Graded (Cr,Al)N\u2009+\u2009Mo:S in Fluid-Free Friction Regime

Components running in fluid-free friction regimes are exposed to harsh conditions leading to increased friction and wear. Thereby, the use of the solid lubricant molybdenum disulfide (MoS2) via lacquers, powders or physical vapor deposition (PVD) coatings enables a friction and wear reduction. However, the tribological performance is limited to low mechanical loads. A promising coating concept already proven for high mechanical loads is the incorporation of the triboactive elements Mo and S in wear resistant hard nitride (Cr,Al)N matrix. In this study the supply mechanism and transfer of the tribofilm build out of the toplayer of the triboactive coating graded (Cr,Al)N + Mo:S under high mechanical loads at humid air were analyzed. Here, the chemical composition of the tribofilm was determined by a combination of Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) and correlated with tribological analysis. The results prove a friction and wear reduction independent of Hertzian pressure in the area of 400 MPa ≤ pH ≤ 1300 MPa due to the formation of a MoS2 and molybdenum oxide MoxOy containing tribofilm, whereby the share of MoxOy dominates compared to MoS2. Based on the results the understanding of the effect of the MoS2 + MoxOy containing tribofilm on the tribological behavior is increased.

Experimental Investigation of the Wear Behaviour of Coated Polymer Gears.

A comprehensive experimental investigation of the wear behaviour of coated spur polymer gears made of POM is performed in this study. The three physical vapour deposition (PVD) coatings investigated were aluminium (Al), chromium (Cr), and chromium nitrite (CrN). Al was deposited in three process steps: By plasma activation, metallisation of Al by the magnetron sputtering process, and by plasma polymerisation. Cr deposition was performed in only one step, namely, the metallization of Cr by the magnetron sputtering process. The deposition of CrN was carried out in two steps: the first involved the metallization of Cr by the magnetron sputtering process while the second step, vapour deposition, involved the reactive metallisation of Cr with nitrogen, also by the magnetron sputtering process. The gears were tested on an in-house developed testing rig for different torques (16, 20, 24 and 30 Nm) and rotational speed of 1000 rpm. The duration of the experiments was set to 13 h, when the tooth thickness, and, consequently, the wear of the tooth flank was recorded. The experimental results showed that the influence of metallisation with aluminium, chromium, and chromium nitrite surface coatings on the wear behaviour of the analysed polymer gear is not significant. This is probably due to the fact that the analysed coatings were, in all cases, very thin (less than 500 nm), and therefore did not influence the wear resistance significantly. In that respect, an additional testing using thicker coatings should be applied in the further research work.

Adhesion and machining performance of PVD AlCrN coatings with an ion beam/laser textured substrate

The insufficient adhesive strength of Physical Vapor Deposition (PVD) coatings is still the key issue that needs to be solved urgently for high-efficiency and high-quality difficult-to-machine materials cutting processing. Currently, laser micromachining is extensively utilized to fabricate micro-textures on the substrate to enhance coatings adhesion. However, laser ablation will cause irregular protrusions inside and on the edges of the textures, which could influence the quality of deposited coatings. Therefore, micro-textures were fabricated on the substrate by an ion beam (IBE)/laser machining method, and the influence of IBE/laser textures on the adhesive strength of PVD coatings is revealed. Firstly, a micro-pits array was prepared on WC/Co substrates with different machining parameters, such as laser repetition frequency and ion beam etching time. The micro-topography and mechanical properties of the substrates with different pretreatments were studied. Then, cathode arc-evaporation technique was utilized to deposit AlCrN film on the IBE/laser textured substrates. The scratch test and dry machining experiments of AISI 316 L stainless steel were performed to evaluate the adhesive strength and machining performance of the coated samples with various pretreated substrates. The results demonstrate that laser texturing and ion beam etching both enhanced the coatings adhesion. Therefore, the critical load of the coatings deposited on the IBE/laser textured substrates with 25 kHz laser repetition frequency and 150 min etching time (F N, C2 = 3.39 N) exhibited the highest value, which was 19.4% higher than that of the conventional AlCrN samples (F N, C2 = 2.84 N). Moreover, the cutting forces F X , F Y , F Z and the friction coefficient of IBE/laser textured coated tool were decreased by 18.7%, 20.6%, 10.2% and 16.7% compared with that of conventional coated tool at the high cutting speed of 200 m/min. Finally, the possible mechanisms of IBE/laser texturing pretreatment on enhancing PVD coatings adhesion were discussed. • A micro-pits array is fabricated by an ion beam (IBE)/laser machining method. • Effect of ion beam (IBE)/laser textures on adhesion of PVD coatings is studied. • Mechanism of IBE/laser texturing to improve coatings adhesion is revealed.

Influence of target power and temperature on roughness and tribology of vanadium-carbon based coatings

In the manufacturing of polyethylene terephthalate bottles, steel molds are used for the blowing process, these molds must have low roughness and friction coefficient as well as mirror-like aspect. This impacts final product features such as transparency and demolding. To achieve this, it is necessary to polish the mold cavities using abrasives such as diamond paste or alumina in suspension; however, no further protection against corrosion and wear can be achieved along its use. In this sense, physical vapor deposition coatings, such as balanced magnetron sputtering, are used to this aim giving average roughness values of 0.05 µm, along with superior corrosion and tribological behavior. Vanadium and Carbon coatings were deposited on American Iron and Steel Institute AISI 1045 steel, which is used in the manufacture of polyethylene terephthalate bottle molds, by means of sputtering technique with balanced magnetron. Deposition experiments were carried out in 8 samples during 30 minutes in an argon atmosphere using 2 to the 3-factorial design with different values of power applied to Vanadium and Carbon target and deposition temperatures. Tribological and roughness behavior was studied in order to evaluate the effect of power applied to target on those properties. In all samples low deposition temperature main effect leads to reduced roughness, in the same way, that low power applied to Vanadium target (40 Watts); however, that roughness is reached when the higher 50 Watts are applied on Carbon target. Similarly, lower coefficients of friction are associated with low roughness and therefore to abovementioned deposition conditions. There a clear effect of low power applied to Vanadium target and temperature to maintain reduced roughness and coefficient of friction which are optimal to coat polyethylene terephthalate bottle molds.

Influence of sequential surface treatment processes on tribological performance of Vanadis 6 cold work tool steel

Wear is the most serious problem in service of moving steel parts. To mitigate it, we have studied phase transformations in the surface layer of Vanadis 6 tool steel obtained after several treatment routes. Changes in wear resistance were examined in particular. There are various ways to improve the quality of surfaces of tool steels for cold working - including mechanical, chemical or physical vapour deposition (PVD) coatings. Several multistage processes of surface layer modification were applied: turning-burnishing, turning-burnishing-PVD, grinding-nitriding, turning-burnishing-nitriding, turning-nitriding-polishing, turning-burnishing-nitriding-polishing, and turning only used as a reference. To provide comparability, samples were subjected to heat treatments in vacuum furnaces with gas quenching until a hardness of ≈62 ± 1 HRC was achieved. Scanning electron microscopy observations, X-ray diffraction analysis, and finally ball-on-disc tribological tests against Al2O3 balls as counterparts provide information about wear and friction values. The best wear resistance – more than ten times higher than after turning only - was achieved for a sample following the turning-burnishing-PVD sequence. The turning-burnishing (130 N)-nitriding sequence may act as an alternative to the grinding-nitriding treatment. Wear rate values for the two latter variants are almost the same.

Improved Adhesion and Tribological Properties of AlTiN-TiSiN Coatings Deposited by DCMS and HiPIMS on Nitrided Tool Steels

Hard coatings, such as AlTiN-TiSiN, deposited by Physical Vapor Deposition (PVD) techniques are widely used in industrial applications to protect and increase the lifetime of industrial components, such as cutting tools, dies, and forming tools. Despite their great properties, such as high hardness and wear and oxidation resistance, they are limited in cases of severe conditions due to the poor adhesion between the coating and the substrate. Duplex treatments have commonly been used to improve the adhesive properties of PVD coatings, especially those of the cathodic arc evaporation type. The purpose of this study is to achieve coatings with the good properties of the Magnetron Sputtering processes but with higher adhesion than that achieved with these techniques, thus achieving coatings that can be used under the most severe conditions. In this work, an AlTiN-TiSiN coating was deposited by a combination of DC Magnetron Sputtering (DCMS) and High-Power Impulse Magnetron Sputtering (HiPIMS) after a gas nitriding pretreatment on 1.2379 and Vanadis 4 tool steels. Mechanical (ultra-microhardness and scratch tests) and tribological tests were carried out to study the improvement in the properties of the coating. Duplex-treated samples showed improved adhesion between the coating and the substrate, with second critical load (Lc2) values greater than 100 N. Furthermore, they showed great toughness and wear resistance. These results show that this type of coating technique could be used in the most extreme applications and that they can compete with other techniques and coatings that to date they have not been able to compete with.

Improving the abrasive wear resistance of biomass briquetting machine components using cathodic arc physical vapor deposition coatings: A comparative study

Abrasive wear of biomass briquetting machine components, such as shedder blades, hammer blades, dies and rams, etc., is the primary limiting factor that affects the economic viability of the biomass briquetting process. In order to overcome this issue, attempts were undertaken in this work to evaluate the applicability of commercially well-established Ti-based metal nitride wear-resistant coatings to reduce abrasive wear. The TiN, TiCrN, and TiAlN coatings were deposited on D3 hard steel using the cathodic arc physical vapor deposition technique. A dry sand rubber wheel tester was used to assess the abrasive wear characteristics of the coatings and bare D3 hard steel. Coating properties, such as hardness, adhesion strength, surface roughness, and residual stress, were also evaluated. The results demonstrated that coating defects (microdroplets and pull-outs/craters), coating hardness, and elastic modulus play a major role in abrasive wear performance. The TiCrN coating has shown the highest abrasion resistance due to high H3/E2 ratio compared to other coatings. The abrasive wear mechanism of the TiAlN coating majorly followed coating spallation due to high compressive residual stress and low adhesion strength. The TiN coating exhibited the worst abrasive wear resistance among the three coatings due to localized ploughing at coating microdroplet and crater sites. Therefore, based on the results, the TiCrN coating has the potential to enhance the service life of briquetting machine components by orders of magnitude compared to uncoated ones

Friction and Wear Behavior of a Physical Vapor Deposition Coating Studied Using a Micro-Scratch Technique

Abstract CrSiN coating was deposited by physical vapor deposition (PVD) magnetron sputtering on XC100 steel substrate. Microstructural and morphological properties were studied using scanning electron microscopy (SEM)/energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), and atomic force microscopy (AFM). Nanoindentation and scratching experiments were conducted to study the mechanical and adhesion behavior. Multi-pass scratch tests were conducted under different sliding conditions. Results showed that CrSiN coating has a dense and compact nanocomposite microstructure consisting of CrN nanocrystallites and SiN amorphous matrix. The CrSiN thin film exhibit hardness and Young's modulus of 30.52 ± 1.85 GPa and 338.32 ± 13.5 GPa, respectively. The H/E, H3/E2, and 1/HE2 ratios were also calculated (H/E ≈ 0.09, H3/E2 ≈ 0.024, and 1/HE2 ≈ 2.86 × 10−07) and used to predict and assess the elastic/plastic and wear resistance. Critical loads LC1, LC2, and LC3 obtained with scratch test, were, respectively, 11.5 ± 0.12, 16.6 ± 0.23, and 20 ± 0.35 N. Multi-pass scratch were analyzed and the friction coefficient (COF), the damage mechanism, and wear volume were determined. The use of an energetic approach allowed to determine the energetic wear coefficient. CrSiN coating revealed a low friction coefficient (around 0.1) and a low energetic wear coefficient (6.3 × 10−7 mm3/N.m). In addition, it was found that multi-pass scratch method has the potential to extract relevant information about wear behavior.

Improved Adhesion of the DLC Coating Using HiPIMS with Positive Pulses and Plasma Immersion Pretreatment

Diamond-like carbon (DLC) coatings are used due to their extraordinary tribomechanical properties, great hardness, high elastic modulus, high wear resistance, low friction coefficient and chemical inertness, which provide them with biocompatibility. Compared to other physical vapor deposition (PVD) coatings of transition nitrides and carbonitrides, DLC has limited adhesion, so it is necessary to develop new techniques to overcome this limitation. This work reports the results of scratch testing for the measurement of adhesion and of tests for wear resistance and nanoindentation in AISI 316L stainless steel coated with a WC:C coating, produced using novel high-power impulse magnetron sputtering (HiPIMS) technology with positive pulses. In addition, the use of a preceding surface modification technique, specifically plasma immersion ion implantation (PIII), was studied with the aim of optimizing the adhesion of the coating. The results show how the coating improved the tribomechanical properties through the use of positive pulse HiPIMS compared to conventional HiPIMS, with an adhesion result that reached critical load values of 48.5 N and a wear coefficient of 3.96 × 10−7 mm3/nm.

A review of physical vapor deposition coatings for rolling bearings

Rolling bearings are critical in automotive engines, wind turbine drive trains, and numerous other mechanical systems. Rolling bearings can suffer from early failures, which result in high operation and maintenance costs. Surface engineering techniques, such as the application of coatings and additives for lubricants have been developed to improve the tribological performance of rolling bearings. In this article, the performance of physical vapor deposition coatings on components working under rolling/sliding contacts and rolling bearings is reviewed. The applications of physical vapor deposition coatings in the rolling bearing industry are summarized. The effects of coating thickness, coating mechanical properties, test conditions, coating bonding layer, and coating architecture on coating performance are discussed. At the end of the article, possible approaches to further improve the performance of physical vapor deposition coatings on rolling bearings are proposed.

Comparative Study of the Wear Behavior of B4C Monolayered and CrN/CrCN/DLC Multilayered Physical Vapor Deposition Coatings Under High Contact Loads: An Experimental Analysis

Abstract There are several ways to characterize the wear resistance of coatings in the laboratory, almost all of them applying relatively low contact pressure, both punctually and over surface contact. Pin-on-disc, reciprocal sliding, and micro-abrasion wear tests are quite common configurations for this purpose. Thus, a gap was identified in terms of characterization of hard physical vapor deposition (PVD) coatings subject to higher levels of contact pressure. This study aims to study and compare the wear behavior of two different coatings made by PVD, a B4C (Boron Carbide) monolayer, less used, and another following a multilayer structure of CrN/CrCN/DLC, to identify the wear mechanisms involved in quite different coatings. Both coatings were initially characterized in terms of chemical composition, thickness, morphology, structure, hardness, and adhesion to the substrate, being subsequently tested in laboratory equipment for wear tests following the block-on-ring configuration and relatively high levels of contact pressure, with a view to study the failure mechanisms of the coatings and their wearrate. CrN/CrCN/DLC multilayered coatings presented a better overall wear behavior, whereas B4C coating showed a good wear behavior regarding the load and configuration used, but in line with the behavior already observed when other wear testing configurations had been used. Thus, under the conditions imposed, CrN/CrCN/DLC coating is the best option when high contact pressure is applied to the coated surfaces.

Structure and Mechanical Properties of PVD and CVD TiAlSiN Coatings Deposited on Cemented Carbide

This work reports the results of our investigation of the structure and mechanical properties of physical vapor deposition (PVD) and chemical vapor deposition (CVD) TiAlSiN coatings deposited on cemented carbide substrates. For the first time, a novel nanocomposite of Ti0.13Al0.85Si0.02N coating deposited from TiCl4-AlCl3-SiCl4-NH3-H2 gas precursors was prepared by low pressure chemical vapor deposition (LPCVD) at 780 °C and a pressure of 60 mbar, while PVD Ti0.31Al0.60Si0.09N coating was prepared using the arc ion plating method. The investigation results including morphology, microstructure, chemical composition, phase component, and hardness were carried out by scanning electron microscopy (SEM) equipped with energy dispersive spectrometer (EDS), transmission electron microscopy (TEM), X-ray diffraction (XRD), and nano-indentator. TEM results revealed that both PVD and CVD TiAlSiN coatings consisted of nanocrystalline embedded in SiNx amorphous. The nanohardness of CVD Ti0.13Al0.85Si0.02N coating obtained in this work was 31.7 ± 1.4 GPa, which was 35% higher than that of the PVD Ti0.31Al0.60Si0.09N coating.

Wear Characterization of Chromium PVD Coatings on Polymeric Substrate for Automotive Optical Components

The automotive industry is a pioneer in solutions that meet market expectations. However, in the automotive industry, some less environmentally friendly technologies are still used, such as electroplating. Due to legislative restrictions in several countries, thin coatings made in a vacuum have been replacing coatings traditionally made by electroplating, mainly in decorative terms. This work is more focused on the use of these coatings made in vacuum for optical applications, namely on headlights and exterior backlit components. Although these components are protected during the period of use, there may be situations of contact during the assembly of the components or their repair, necessary to safeguard and to ensure that these coatings have the scratch and wear resistance needed to withstand any treatment deficiency during the operations referred to above. Therefore, this work is essentially focused on the study of the wear resistance of Cr coatings made by PVD (Physical Vapour Deposition) on polymeric substrates. To this end, the coatings previously studied have now been subjected to micro-abrasion tests, with a view to assessing their wear resistance. For this purpose, alumina abrasive has been used, and the wear mechanisms observed in the coatings were studied. The abrasion and scratch tests showed that the most stable film has the one provided with 10-layers, showing greater wear resistance as well, greater adhesion to the substrate and less cohesive failures in the performed tests. Given the nature of the substrate and the coating, the results obtained are very promising, showing that these 10-layer Cr thin coatings can overcome any careless operation during manufacturing, assembly and repair processes, when applied in lightning or backlit components in motor vehicles.

Cavitation erosion of monolayer PVD coatings – An influence of deposition technique on the degradation process

TiN, Cr–N, W, WC and WC/a-C: H coatings produced using Physical Vapour Deposition (PVD) method were investigated. TiN and Cr–N coatings were deposited using the cathodic arc evaporation (CAE-PVD) and reactive magnetron sputtering (RMS-PVD) techniques. W, WC and WC/a-C: H coatings were produced by the reactive magnetron sputtering (RMS-PVD) technique. Coatings were exposed to cavitation using a tunnel with a system of barricades. The influence of the deposition technique on the structure of the coating as well as on the degradation process has been discussed. It has been shown which degradation processes are independent of deposition techniques and which are dependent on them. The deposition technique had a higher impact on the droplet density (over 20-fold) than the deposited compound (nearly 2-fold). The highest density of droplets had TiN coatings deposited by the CAE-PVD technique, while the lowest had W-based coatings deposited by the RMS-PVD technique. The first symptoms of cavitation erosion of PVD coatings included the removal of some droplets from the coating surface and the coating undulation. The size of droplets did not affect their removal. Droplets can be divided into 1) droplets easy removable from the coating, 2) droplets requiring specific impact energy for their removal, and 3) droplets not removable from the coating, regardless of the degree of cavitation erosion development. Regardless of the deposition technique (CAE and RMS) and coating type (TiN or Cr–N), cavitation caused the phase transformation Fe-γ→Fe-α′ in the austenitic steel substrate. The intensity of this transformation depends on the deposition technique. High intensity of the phase transformation was obtained in the RMS coatings which are characterised by a low density of droplets. On the surface of the RMS coatings a larger size of puncture was formed than on the CAE coatings. It is shown that the droplets play an important role in the degradation as they are stress concentrators and also absorb some of the impact energy and affect the amount of energy used for fracture and transferred to the substrate.

Corrosion and Electrochemical Impedance Spectroscopy of Thin TiALN and TiCN PVD Coatings for Protection of Ballast Water Screen Filters

Abstract The electrochemical impedance spectroscopy (EIS) and corrosion behaviour of physical vapour deposited (PVD) TiAlN and TiCN coatings of 50 µm mesh shaped AISI 316 stainless steel were estimated under simulated marine conditions (3.5 wt. % NaCl solution). The coatings were prepared by creating adhesive Cr-CrN interlayer with the thickness of about 0.3 µm. The obtained thicknesses of produced coatings were measured to be in a range between 2 and 3.5 µm. The presence of protective coatings leads to corrosion potential (Ecorr ) shifting to more positive values as compared to the bare stainless steel. This effect indicates higher protection efficiency of coated steel under marine conditions. The protective behaviour of produced coating leads to the decreased corrosion current density (jcorr ) by indicating up to 40-fold higher polarization resistance as compared to resistance of the naturally formed oxide layer over the stainless steel. The Nyquist and Bode plots were obtained with the help of EIS measurements by applying alternating potential amplitude of 10 mV on observed Ecorr . The obtained plots were fitted by appropriate equivalent circuits to calculate pore resistance, charge transfer resistance and capacitance. The present study reveals that pore resistance was the highest in the case of TiCN coating (Rpore =3.22 kΩ·cm2). The increase in duration of the immersion up to 24 h leads to change in the capacitive behaviour of the coatings caused by the penetration of the aqueous solution into pore system of TiCN coating with low wettability and surface passivation of reactive TiAlN coating. The presence of defects was confirmed by examining the obtained samples with the help of the scanning electron microscope.

Development of surface coatings for high-strength low alloy steel filler wires and their effect on the weld metal microstructure and properties

The lightweight construction of steel structures is often limited by the mechanical properties of the weld metal. The strength values of modern base materials are not achieved in the weld metal. There is a considerable need to develop welding consumables that allow the processing of modern fine-grained structural steels without limiting their potential. The Physical Vapor Deposition (PVD) coating of welding wire electrodes can increase the strength of the weld metal of a Mn4Ni2CrMo welding wire electrode by up to 30%. By using different coating elements, the Hall–Petch relationship can be exploited and such an increase in strength can be achieved. Especially by applying titanium, vanadium, and yttrium coatings, the strength of the weld metal can be increased. Due to a multilayer structure of the coating, the weld metal and the process can be influenced independently of each other. The effects of mono-element coatings and multi-component coatings on the weld metal and the process are discussed. PVD coatings allow welding wire electrodes to be individually adapted to the requirements.