Duplex Surface Treatment Research Articles

Enhanced properties of alumina coating produced by combining plasma electrolytic oxidation and ultrasonic shot peening

A short-duration ultrasonic shot peening (USP) is used as a post-treatment to plasma electrolytic oxidation (PEO) coatings produced on a 2017 aluminium alloy under various sparking regimes (arc or soft) and time durations. USP is detrimental on PEO layers produced for short durations and under the arc regime because the typical pancake structure at the topmost surface is partially blasted. In contrast, PEO layers grown under the soft regime not only keep their structural integrity after short duration USP but also experienced a densification of their internal sublayer and a resurfacing of the sponge structure at the external sublayer. Under the specific PEO soft regime, the proposed duplex surface treatment makes the coating harder with a higher fracture toughness compared to the as-produced PEO coating.

Interfacial alloying between expanded austenite and Ti(AlCu)N coating for enhanced cavitation erosion resistance

Duplex surface treatments, combining nitriding and PVD coatings, have been considered as potential solutions to enhance material cavitation erosion resistance. This study investigates 316 L stainless steels after active screen plasma nitriding (ASPN), Ti(AlCu)N coating and duplex-treatment (Duplex) for enhanced cavitation erosion resistance. We elucidate a ‘denitriding - nitriding’ alloying behavior in association with high-energy ion sputtering for the interface between the nitrided case and the Ti(AlCu)N coating in the duplex-treated 316 L surface. Comparing the cavitation erosion performance among ASPN, Ti(AlCu)N and Duplex, the lowest weight loss of the duplex-treated surface is attributable to the enhanced load-bearing capacity from the multilayer system and the strong coating adhesion (HF1) after metallurgical evolution at the interfacial zone.

Effect of duplex surface treatment on the impact properties of maraging steel produced by laser powder bed fusion

The impact properties of an L-PBF 18Ni-300 maraging steel were investigated after different heat and duplex (nitriding and PVD coating) surface treatments. Impact energy is almost isotropic. Contrary to expectations, impact energy is not decreased by surface treatments, since the effect of surface embrittlement of nitriding is compensated by the increase in the austenite content. An important role is played by the geometry of the notch where the surface hardening is lower than in the flat surface of the Charpy specimens.

Effects of dispersed α-Al2O3 particles into a cold-sprayed aluminium coating on its subsequent oxidation by the PEO process

The present study focused on the use of a duplex surface treatment combining cold-spray deposition and plasma electrolytic oxidation (PEO) to produce an aluminium metal matrix composite coating, including dispersed α-Al2O3 particles, with improved tribological properties. Al/α-Al2O3 composite coatings were first deposited by cold-spray, with various thickness and proportion in α-Al2O3 particles, and, then partially oxidized by PEO under various processing durations and sparking regimes (arcs or soft regime). The feasibility of cold-spraying thick, compact and adherent aluminium coatings containing well-dispersed α-Al2O3 particles (up to 14 vol%) was demonstrated in this work. It was also pointed out that the addition of hard α-Al2O3 particles into the spray composition tends to densify the deposited aluminium coating. This was related to a stronger peening effect which, in turn, decreases the growth kinetic of the subsequent PEO oxide layer. The presence of dispersed α-Al2O3 particles was found to promote the formation of the corundum alumina phase in the PEO oxide layer by triggering the transition to the soft sparking regime earlier. It was also observed that dispersed α-Al2O3 particles remain unaffected throughout the PEO oxide layers formed within the conventional arcs sparking regime while they undergo a morphological transformation within the specific soft sparking regime. This was explained by considering the different type of micro-discharges that initiate during each regime. Finally, sliding wear tests revealed that the incorporation of α-Al2O3 particles into the cold-sprayed coating resulted in a slight decrease in the friction coefficient and the wear rate of the produced PEO layers.

Investigation of combined surface treatments and coatings to increase the wear behavior of heat treatable steels

A combination treatment of nitriding and induction hardening can achieve high hardness depths in short treatment times and can therefore be seen as an alternative to deep nitriding. However, the compound layer, which makes a significant contribution to the wear resistance of nitrided components, decomposes during the induction heat treatment of the nitrided part. Therefore, the tribological behavior of parts processed this way is affected. In the present work, the wear behavior of surface layers resulting from combined heat treatment of EN42CrMo4 and PVD a-C:H(:Si) coating is investigated and evaluated. For the wear testing, a two-disk test rig was used. The wear was determined gravimetrically and by optical evaluation of the wear tracks. It was found, that the wear resistance of the investigated heat-treatable steel can be improved by duplex surface treatments such as nitriding and induction hardening as well as nitriding and PVD a-C:H(:Si) coating compared to the heat treated-only condition. By triplex treatment, no further improvement of the wear resistance could be observed.

A new strategy to prepare alumina-zirconia composite or multilayered coatings by combining cold-spray deposition and plasma electrolytic oxidation

In the present study, the feasibility of the elaboration of alumina (Al2O3) - zirconia (ZrO2) composite coatings on steel was explored by combining cold-spray deposition and plasma electrolytic oxidation (PEO). More specifically, two different configurations were investigated. The first configuration consisted in successively cold-spraying an aluminium layer first and a zirconium layer second, giving rise to a Zr / Al metallic multilayer coating that was then partially oxidized by PEO. In this configuration, microstructural characterizations evidenced the formation of a ZrO2 / Zr / Al composite multilayer coating on steel. The second configuration consisted in simultaneously cold-spraying aluminium and zirconium into a (Zr, Al) metallic composite monolayer prior to its partial oxidation by PEO. In this case, results evidenced the formation of a (ZrO2, Al2O3) / (Zr, Al) composite multilayer coating on steel. Finally, the present study demonstrated that the duplex surface treatment combining cold-spray deposition and PEO method is viable as a new route to produce ceramic/metal composite coatings on various metallic alloys.

An Investigation Into the Synergistic Effect of CAPVD Cr/CrN Nanolayered Coating Deposition and Hard-Anodizing Methods on Fretting Fatigue Life of 7075-T6 Aluminum Alloy

The influence of duplex surface treatment including a Cr/CrN nanolayered coating deposited by cathodic arc physical vapor deposition (CAPVD) and an alumina layer coated by hard-anodizing method on the fretting fatigue strength of Al7075-T6 alloy is studied in this investigation. Although fretting fatigue life of both single Cr/CrN coated alloy and Cr/CrN coating deposition onto hard-anodized alloy was increased in high cycle fatigue (HCF) regime, employing an alumina layer as a pretreatment for the Cr/CrN deposition enhanced the life improvement in the HCF regime. In low cycle fatigue (LCF) regime, despite a decrease in fretting fatigue life of both Al7075-T6-coated alloys, using the alumina layer beneath the Cr/CrN coating resulted in mitigation of fretting fatigue life deterioration. Interestingly, a single-hard-anodized specimen represented a completely different variation trend of fretting fatigue life in HCF and LCF regimes. Unlike the as-received and single-hard-anodized specimens, Cr/CrN-coated specimens did not bear the maximum axial stress, 260 MPa. Partial slip regime was mostly seen at the contacting area.

Investigation of structural, electrical and tribological properties of duplex surface treated and aged Cu−Cr−Zr alloy

AbstractIn this study, Cu−Cr−Zr alloy specimens were first subjected to aging heat treatment at 500 °C for two different durations (2 hours and 4 hours). Three different coating processes (silver, silver/copper duplex, and copper/silver duplex) were applied to the aged specimens using the physical vapor deposition method. Tensile test, microhardness measurement, wear test, electrical conductivity measurement and structural analysis (x‐ray diffraction and scanning electron microscope) were applied to the specimens. After the aging processes, the highest hardness and strength values of the Cu−Cr−Zr alloy were obtained in the specimens that were aged at 500 °C for 4 hours. When the wear resistance and electrical conductivity of the coated specimens were examined, it was determined that the specimens with duplex surface treatment performed better.

Improved Wear Resistance of Low Carbon Steel by Duplex Surface Treatment Combining Cathodic Plasma Electrolytic Nitrocarburising and Anodic Plasma Electrolytic Polishing

Improved Wear Resistance of Low Carbon Steel by Duplex Surface Treatment Combining Cathodic Plasma Electrolytic Nitrocarburising and Anodic Plasma Electrolytic Polishing

The Effect of a Duplex Surface Treatment on the Corrosion and Tribocorrosion Characteristics of Additively Manufactured Ti-6Al-4V

The use of additively manufactured components specifically utilizing titanium alloys has seen rapid growth particularly in aerospace applications; however, the propensity for retained porosity, high(er) roughness finish, and detrimental tensile surface residual stresses are still a limiting factor curbing its expansion to other sectors such as maritime. The main aim of this investigation is to determine the effect of a duplex treatment, consisting of shot peening (SP) and a coating deposited by physical vapor deposition (PVD), to mitigate these issues and improve the surface characteristics of this material. In this study, the additive manufactured Ti-6Al-4V material was observed to have a tensile and yield strength comparable to its wrought counterpart. It also exhibited good impact performance undergoing mixed mode fracture. It was also observed that the SP and duplex treatments resulted in a 13% and 210% increase in hardness, respectively. Whilst the untreated and SP treated samples exhibited a similar tribocorrosion behavior, the duplex-treated sample exhibited the greatest resistance to corrosion-wear observed by the lack of damage on the surface and the diminished material loss rates. On the other hand, the surface treatments did not improve the corrosion performance of the Ti-6Al-4V substrate.

A comprehensive study on the fatigue properties of duplex surface treated Ti6Al4V by plasma nitriding and DLC coating

This study aims to investigate the effects of duplex surface treatment consisting of plasma nitriding and DLC coating on the fatigue properties of Ti6A4V alloy. For this investigation, Ti6Al4V samples were plasma nitrided at 650 °C, 700 °C and 750 °C for 1, 2 and 4 h and then DLC films were produced on the plasma nitrided samples. The structural, mechanical and morphological features of the samples were characterized by XRD, SEM, micro hardness tester and scratch tester. Fatigue tests were performed on the samples by using stress life method. On the surface and sub-surface of the samples, a compound layer and a diffusion zone were formed by plasma nitriding, respectively and XRD results revealed that these layers consisted of Ti2N and TiN phases. The raising process time and temperature caused to increase the thickness of these layers and they also increased the surface hardness of the samples. On the other hand, DLC coated samples exhibited more surface hardness than untreated and all the plasma nitrided samples. Fatigue analyses revealed that plasma nitriding reduced the fatigue strength of the material in all process conditions. Although plasma nitriding formed hard surface and sub-surface layers, the brittle structure of the layers and the great difference of elastic modulus between the substrate and nitride layers caused to decrease the fatigue strength of the material. Although DLC coating increased the fatigue strength of untreated and plasma nitrided samples at 650 °C for 1 h, 700 °C and 750 °C for 4 h), the fatigue strength of duplex treated samples (plasma nitrided at 650 °C for 1 h, 700 °C and 750 °C for 4 h and DLC coated) was lower than the fatigue strength of untreated material, similar to only plasma nitrided materials. This showed that the fatigue strength of duplex treated Ti6Al4V was controlled by plasma nitriding.

TRIBOCORROSION PROPERTIES OF BORIDED AND Al2O3-COATED NiTi MATERIAL

The purpose of this study was to investigate the tribological properties of NiTi shape-memory alloy that was borided and coated with Al2O3 using the electrophoretic deposition (EPD) method. For the study, the sample surface was borided for 1 and 4 h at 800°C with the method of pack boriding, and the surface of the sample that was borided was coated with Al2O3 using the EPD method. The tribocorrosion properties of the untreated samples, borided samples, and borided and (duplex) Al2O3-coated samples were investigated and characterized using XRD and SEM devices. Accordingly, following the boriding treatment on the NiTi material, Al2O3 coating was successfully carried out with the EPD method. In comparison to the untreated samples, the tribocorrosion resistance of the surface-treated samples under a load of 3 N in a 3.5% NaCl solution increased. Additionally, among all samples, those that were subjected to the duplex surface treatment had the best tribocorrosion properties.

On the effect of Cr/CrN nanolayered coating deposited by Arc-PVD method on axial fretting fatigue behavior of Al7075-T6 alloy

The influence of Cr/CrN nanolayered coating deposited by Arc-PVD technique and re-heat treatment on fretting fatigue behavior of Al7075-T6 alloy was investigated. It has been demonstrated that a single Cr/CrN coating deposition at 300 °C is more efficient than both coating deposition at a lower temperature (150 °C) and duplex surface treatment. The latter includes coating deposition at 300 °C and re-heat treatment. The most increase for fretting fatigue life was around 200 % and was obtained for the lowest axial stress of 130 MPa which corresponds to high cycle fatigue regime (HCF). However, in low cycle fatigue regime (LCF), the fretting fatigue life of the coated specimens reduced significantly in comparison to the as-received samples by 60 % at most. Re-heat treatment after the Cr/CrN coating deposition at 300 °C improved the fretting fatigue life of samples in LCF regime by 33 % for the highest axial stress of 260 MPa. In HCF regime, however, the increase in the fretting fatigue life of re-heat treated coated samples was no more than 121 %, which was achieved for 130 MPa axial stress. This was around half of the maximum life improvement achieved for the single coated specimen at 300 °C.

Structure and mechanical properties of MAO coatings formed on aluminum-coated titanium alloy

ABSTRACT Application of titanium alloys is restricted due to their low hardness and poor wear resistance. Duplex surface treatment consisting of depositing of Al coating by arc ion plating (AIP) plus micro-arc oxidation (MAO) was carried out on Ti6Al4V alloy to improve its tribological performance. Ceramic coating mainly composed of α-Al2O3, γ-Al2O3 and mullite was fabricated on the aluminum-coated titanium alloy after the MAO treatment, and its thickness, compactness and hardness increased with the MAO time before the titanium alloy was oxidized. After the substrate titanium alloy was locally oxidized due to oxygen anions inward migration, a thin transition layer containing titanium oxides and aluminum titanate formed and incorporation of Ti in the alumina coating occurred. Occurrence of the strong eruptible discharges at these positions was facilitated probably due to the large difference in permittivity of the alumina and the titanium oxides, which led to the formation of penetrating cracks in the MAO coating. The hardness and compactness of the ceramic coating decreased. Tensile test results showed bonding strength of MAO ceramic coating/aluminum layer/titanium alloy substrate system was more than 40 MPa, and the maximum value could reach around 68 MPa. The bonding strength of the ceramic coating/titanium alloy substrate system decreased to around 34 MPa due to the weak bonding between the alumina ceramic coating and the titanium alloy substrate. Tribological test results show wear resistance of titanium alloy was greatly improved due to the fabrication of hard alumina ceramic coating on titanium alloy.

The effect of Bias configuration on the properties of AlCrN based thick coatings deposited by Cathodic Arc Evaporation

Die wear in forming high strength steels (HSS) operations causes increased die maintenance cost and scrap rate, being a major obstacle for automation industries to meet upcoming market requirements. Advanced PVD (Cathodic Arc) coatings of high thicknesses (> 15 μm) can be optimum solution from both an economic and technical point of view, compared to the current CVD or duplex surface treatments. Bias voltage becomes a key parameter to minimize residual stresses in the coating during its growth while ensuring optimal mechanical properties of the coating. Different configurations and their relation to coating properties have been studied. Thick coatings (up to 18 μm thickness) with optimal adhesion have been deposited at 7 μm/h under bipolar bias voltage conditions. The as deposited coatings are showing promising performance in real deep drawing production process.

Investigation of the wear and corrosion behaviors of CrN films onto oxynitriding-treated AISI H13 alloy steel by the direct current magnetron sputtering process

• The optimal deposition time of CrN films onto oxynitriding-treated samples was 2.5 h. • Study confirmed that the 2.5 h specimen had the smaller surface roughness (20.5 nm). • 2.5 h specimen possessed the most stable columnar crystal structure of CrN films. • CrN/oxynitriding treated had the relatively lowest wear volume loss (5.38 × 10 −6 mm 3 ). • Duplex surface treatment possesses the lowest corrosion current (4.30 × 10 −5 A·cm −2 ). In the research reported herein, CrN films were coated onto oxynitriding-treated AISI H13 alloy steel using direct current magnetron sputtering deposition technique. The AISI H13 substrate has a 50-µm oxynitrided top layer with a hardness of 1000 HV 0.05 . The duration of the CrN film deposition were varied while the sputtering parameters were kept constant with constant bias of -25 V, power of 100 W, Ar and N 2 gas flow rate of 45 and 30 sccm, respectively, and deposition temperature of 300 °C. The duplex oxynitride/CrN coating exhibited optimal properties when the CrN film was 3.35 µm thick after 2.5 h deposition. This sample showed good adhesion to the oxynitrided layer. It also had the best wear resistance with wear loss volume and specific wear rate was 5.38 × 10 −6 mm 3 and 1.35 × 10 −6 mm 3 ·m − 1 ·N −1 , and good corrosion resistance with a corrosion current of 4.30 × 10 −5 A·cm −2 and polarization resistance of 604.66 Ω·cm 2 . Overall, the CrN/oxynitriding duplex surface treatment is effective in improving the properties of oxynitrided AISI H13 alloy steel.

Corrosion and Wear Properties of Cr Coating and ZrO2/Cr Bilayer Coating on Zr-4 Alloy

In this study, duplex surface treatments were used to prepare a ZrO2/Cr bilayer coating on zirconium alloy cladding for enhancing the wear and corrosion behaviors. The surface and cross-section morphology of coated Zr-4 alloy was characterized; the results show that the Cr- and ZrO2/Cr-coated samples had similar morphology, and more obvious surface undulates could be observed on the ZrO2/Cr coating than the pure Cr coating owing to the rough surface of the plasma electrolytic oxidation coating. Wear and electrochemical behavior in 1200 mg/L H3BO3 and 2.2 mg/L LiOH solutions of original and coated Zr-4 alloy were investigated. The electrochemical corrosion test indicated the coated Zr-4 alloy exhibited better corrosion resistance behavior than the original Zr-4 alloy. The potentiodynamic polarization curves and corrosion morphology suggest the pitting corrosion occurred on the surface of the original and coated Zr-4 alloy. The ZrO2/Cr-coated Zr-4 alloy had better corrosion resistance due to the dual protection of the PEO layer and Cr coating. The wear behavior of the original and coated Zr-4 alloy was also investigated under a constant load of 5 N. The results reveal that the coated Zr-4 alloy had better wear resistance, and the PEO layer was found to significantly enhance the wear resistance of the Zr-4 alloy.

Duplex surface treatment on ASTM A-36 steel by slide burnishing and powder pack boriding

In this work, a novel duplex surface treatment (DST) was done on ASTM (American Society for Testing and Materials) A-36 steel bar by combining burnishing and boriding processes. Initially, the slide burnishing method on ASTM A-36 steel was carried out using a burnishing force of 200 N and a travel speed of 127 mm/min. Then, powder pack boriding process was conducted on burnished steel at 950 °C for 5 h. The X-ray diffraction analysis shows the formation of the Fe2B phase. The hardness increases from 216 HV0.05 to 2290.3 HV0.05 for the burnished-boride sample. According to electrochemical impedance spectroscopy (EIS) and Tafel (potentiodynamic polarization) results, burnished-boride steel showed a higher corrosion resistance than that of boride steel.

Enhanced Wear Resistance and Corrosion Resistance of 304 Austenitic Stainless Steel by Duplex Surface Treatment

Duplex surface treatment (DST) is performed on 304 austenitic stainless steel (304ss) by Ni/Al2O3‐coating pretreatment and atmospheric gas nitriding at 400 °C and below. The microstructure, microhardness, wear resistance, and corrosion resistance of the samples are investigated. Microhardness significantly increases to 853.66 ± 39.76 HV0.05 due to a continuous nitrided layer that is formed on the DST 304ss at 400 °C. Compared with the single nitrided sample, the wear volume loss of the surface and nitrided layer of DST 304ss at 400 °C decreases by 92.0% and 97.2%, respectively. The obvious pitting corrosion phenomenon is presented on the surface of the single nitrided 304ss, while not on the nitrided layer of DST 304ss at 400 °C. The results show that the DST realizes the low‐temperature nitriding of 304ss and effectively improves the microhardness, wear resistance, and corrosion resistance of 304ss. The Ni/Al2O3‐coating pretreatment is expected to develop into a new type, low‐cost, and efficient method to promote nitriding.

Wear and Corrosion Resistance of CrN Films on Oxynitriding-treated Vanadis 8 Tool Steel <i>via</i> the DC Magnetron Sputtering Process

This research coated CrN films on oxynitriding-treated Vanadis 8 tool steel using the DC magnetron sputtering process of the PVD technique. The experimental parameters include different gas flow rates (Ar/N2 was 20/20, 24/16, 28/12, and 32/8, respectively), with a bias of −50 V, power of 100 W, deposition temperature of 300°C, and deposition time of 180 min, respectively. The experimental results show that Vanadis 8 tool steel can form an effective oxynitriding layer with a depth of about 50 µm after the oxynitriding treatment, and the surface hardness increased to about 1400 HV0.05. Furthermore, the duplex coating layers exhibited optimal properties when the CrN films treated at an appropriate gas flow rate of Ar/N2 was 24/16. Meanwhile, according to XRD analysis, the coating layer has a relatively high content of CrN composition, as well as the best wear resistance (the lowest specific wear rate when the loads of 2 N and 4 N were 2.05 × 10−5 and 1.56 × 10−5 mm3·m−1·N−1) and good corrosion resistance (in a 3.5 wt% NaCl environment, Icorr = 3.05 × 10−4 A·cm−2, Rp = 362.52 Ω·cm2). Overall, this study reveals that the CrN/oxynitriding duplex surface treatment could effectively improve the wear and corrosion properties of Vanadis 8 tool steel.