316L Steel Substrates Research Articles

Effect of Al and Ag dopants on the corrosion resistance of the AISI 316L-YSZ system

We present results for the deposition of coatings of zirconium stabilized with Yttria (YSZ) and doped with aluminum and silver. The coatings were grown from an YSZ ceramic target symmetrically covered with metallic (Al, Ag) pieces on AISI 316L steel substrates, via the RF sputtering technique. The microstructure of the coatings was characterized by means of X-ray diffraction (XRD), the chemical composition was determined through X-ray dispersive energy (EDX) analysis, and the electrochemical response was evaluated via impedance (EIS) and Tafel corrosion techniques. The XRD analysis showed that the coatings exhibited peaks belonging to the target material, dopant elements, and oxides such as Al2O3. Electrochemical analysis indicated an increase in the corrosion resistance of the coatings grown on aluminum oxide.

Improving the Adhesion Resistance of the Boride Coatings to AISI 316L Steel Substrate by Diffusion Annealing

In this study, new results about the practical adhesion resistance of boride coating/substrate system formed at the surface of AISI 316 L steel and improved by means of a diffusion annealing process are presented. First, the boriding of AISI 316 L steel was performed by the powder-pack method at 1173 K with different exposure times (4-8 h). The diffusion annealing process was conducted on the borided steels at 1273 K with 2 h of exposure using a diluent atmosphere of boron powder mixture. The mechanical behavior of the boride coating/substrate system developed by both treatments was established using Vickers and Berkovich tests along the depth of the boride coatings, respectively. Finally, for the entire set of experimental conditions, the scratch tests were performed with a continuously increasing normal force, in which the practical adhesion resistance of the boride coating/substrate system was represented by the critical load. The failure mechanisms developed over the surface of the scratch tracks were analyzed; the FeB-Fe2B/substrate system exhibited an adhesive mode, while the Fe2B/substrate system obtained by the diffusion annealing process showed predominantly a cohesive failure mode.

Laser Surface Treatment of Stellite 6 Coating Deposited by HVOF on 316L Alloy

This research aimed to study the effects of laser glazing treatment on microstructure, hardness, and oxidation behavior of Stellite 6 coating deposited by high velocity oxygen fuel (HVOF) spraying. The as-sprayed Stellite 6 coating (ST-HVOF) was subjected to single-pass and multiple-pass laser treatments to achieve the optimum glazing parameters. Microstructural characterizations were performed by x-ray diffractometry and field emission scanning electron microscopy equipped with energy-dispersive spectroscopy. Two-step optimization showed that laser treatment at the power of 200 W with a scan rate of 4 mm/s causes a surface layer with a thickness of 208 ± 32 µm to be remelted, while the underlying layers retain the original ST-HVOF coating structure. The obtained sample (ST-Glazing) exhibited a highly dense and uniform structure with an extremely low porosity of ~0.3%, much lower than that of ST-HVOF coating (2.3%). The average microhardness of ST-Glazing was measured to be 519 Hv0.3 indicating a 17% decrease compared to ST-HVOF (625 Hv0.3) due to the residual stress relief and dendrite coarsening from submicron size to ~3.4 µm after laser treatment. The lowest oxidation mass gain was obtained for ST-Glazing by 2 mg/cm2 after 8 cycles at 900 °C indicating 52 and 84% improvement in oxidation resistance in comparison to ST-HVOF and bare 316L steel substrates, respectively.

On the wear of TiB x /TiSi y C z coatings deposited on 316L steel

Abstract Bilayer TiB x /TiSi y C z coatings were formed on AISI 316L steel substrates by dual beam ion beam assisted deposition from TiB x and TiSi y C z targets. Coated and uncoated substrates were subjected to nanoindentation, scratch and friction-wear tests. Scratch and ball-on-disc tests were conducted in non-lubricated sliding, using a diamond pin and 100Cr6 steel ball, respectively. Scanning electron microscopy and atomic force microscopy were used to examine the surfaces of coated samples, before and after tests. To investigate wear mechanisms in the coating–substrate systems, thin foils were prepared from worn areas for transmission electron microscopy observations. TiB x /TiSi y C z coatings proved to be well adherent to steel substrates. The main wear mechanism was of abrasive type. Intensive plastic deformation of steel substrate under critical loads was revealed.

Tribological properties of BixTiyOz films grown via RF sputtering on 316L steel substrates

In this paper, we present the results obtained in surface chemical analysis, morphological characterization and evaluation of tribological properties of coatings of amorphous bismuth titanate (BixTiyOz) deposited on substrates made of 316L stainless steel using rf sputtering technique. The chemical elemental analysis was performed using Auger electron spectroscopy (AES), the morphology of the coatings was determined by atomic force microscopy (AFM). Measures of friction coefficient and wear rate were obtained by ball on disc test. EEA analyses allowed to establish that the first 10 nm of the coatings are comprised probably of Bi4Ti3O12 and Ti2O3, AFM measurements indicate that the coatings have an average roughness of 22.28nm and grain size of 50nm. Finally, the tribological tests established that the coefficient of friction and wear rate of the coated steel has similar values to the bare steel.

Effect of Track Overlap on the Microstructure and Properties of the CoCrMoSi PTA Coatings

Broadly speaking, the research and design of coatings are generally studied by way of single-track deposits; otherwise, the development of a coated part entails the understanding of how multi-track welding influences the microstructure and properties of the surface. This study evaluated the effect of track overlap on the microstructure and properties of the CoCrMoSi Tribaloy T400 alloy coatings produced on AISI 316L steel substrate. The characterization was performed by scanning electron microscopy, hardness and X-ray diffraction. The correlation between the degree of overlap and performance of the coatings was assessed by wear tests. The single track deposits showed hypoeutectic microstructure as a result of high Iron, Chromium and Nickel content. From the second track on, the chemical composition was displaced back to eutectic and then to hypereutectic with overlap of 25 and 50%, respectively. The microstructure dictated the hardness of the coatings (527 – 701 HV0.5) and the lower mass loss rate was measured for hypereutectic with primary Laves phase.

Microstructure and Properties of Nickel-based C276 Alloy Coatings by PTA on AISI 316L and API 5L X70 Steel Substrates

This work assessed Ni-based C276 alloy coatings by PTA with different degree of interaction with AISI 316L and API 5L X70 steel substrates. Track geometry, dilution and microstructure of coatings were evaluated by optical, scanning electron microscopy and X-ray diffraction. Properties were evaluated by hardness and wear tests. Microstructure exhibited austenite Ni-FCC dendrites and interdendrictic regions containing carbides. Dilution from 4,9 to 25,4% for coatings on API 5L X70 leaded to hardness ranging from 283 to 243 HV0,5. Otherwise, dilution between 22,3 and 41,5% for coatings on AISI 316L induced hardness from 267 to 225 HV0,5. Higher interaction with the substrate leaded to 19,8% increase of mass loss rate on API 5L X70 coatings. The slight difference for coatings properties deposited on different substrates indicated that the degree of interaction was the most significant factor.

Boundary Lubrication Mechanisms of Molybdenum Film by MoDTC and ZDDP Additives

Molybdenum (Mo) film is deposited by Ion Beam Assisted Deposition (IBAD) on the 316L steel substrate surface in this experiment. The micro structure and nanohardness of the film are tested by Scanning Electronic Microscope (SEM) and nanoindentation tester. The tribological behaviors of Mo film under ZDDP and MoDTC lubrication are evaluated by SRV test machine. The tribo-film formed on the worn surfaces is investigated by X-ray photoelectron spectroscopy (XPS) to find out the tribological mechanisms between the Mo film and the two additional additives. The result shows that Mo film not only has friction reduction property but also has wear assistant property under ZDDP and MoDTC lubrication. As element Mo has advantage on promoting the deposition of these two lubricating additives.

Crack Propagation Resistance of α-Al2O3 Reinforced Pulsed Laser-Deposited Hydroxyapatite Coating on 316 Stainless Steel

Hydroxyapatite (HA) is a widely used bioceramic known for its chemical similarity with that of bone and teeth (Ca/P ratio of 1.67). But, owing to its extreme brittleness, α-Al2O3 is reinforced with HA and processed as a coating via pulsed laser deposition (PLD). Reinforcement of α-Al2O3 (50 wt.%) in HA via PLD on 316L steel substrate has shown modulus increase by 4% and hardness increase by 78%, and an improved adhesion strength of 14.2 N (improvement by 118%). Micro-scratching has shown an increase in the coefficient-of-friction from 0.05 (pure HA) to 0.17 (with 50 wt.% Al2O3) with enhancement in the crack propagation resistance (CPR) up to 4.5 times. Strong adherence of PLD HA–Al2O3 coatings (~4.5 times than that of HA coating) is attributed to efficient release of stored tensile strain energy (~17 × 10−3 J/m2) in HA–Al2O3 composites, making it a potential damage-tolerant bone-replacement surface coating.

Impact of dilution on the microstructure and properties of Ni-based 625 alloy coatings

Nickel-based alloy IN 625 is used to protect components of aircrafts, power generation and oil refinery due to an association of toughness and high corrosion resistance. These properties are associated with the chemical composition and microstructure of coatings which depend on the processing parameters and the composition of the component being protected. This paper assessed impact of dilution on the microstructure and properties of the Ni alloy IN 625 deposited by Plasma Transferred Arc (PTA) on two substrates: carbon steel API 5L and stainless steel AISI 316L. Differences due to the interaction with the substrate were maximized analyzing single layer coatings, processed with three deposition current: 120, 150 and 180 A. Correlation with a cast Nickel-based alloy sample contributed to assess the impact of dilution on coatings. Dilution was determined by the area ratio and Vickers hardness measured on the transverse section of coatings. Scanning electron and Laser confocal microscopy and X-ray diffraction analysis were carried out to characterize the microstructure. Results indicated the increasing dilution with the deposition current was deeply influenced by the substrate. Dilution ranging from 5 to 29% was measured on coatings processed on the API 5L steel and from 22 to 51% on the low thermal conductivity AISI 316L steel substrate. Differences on the microstructure and properties of coatings can be associated with the interaction with each substrate. Higher fraction of carbides account for the higher coating hardness when processing on API 5L whereas the low thermal conductivity of AISI 316L and the higher Fe content in solid solution contributed to the lower hardness of coatings.

Investigation of structural, tribological and corrosion properties of electroless Ni–B coating deposited on 316L stainless steel

The AISI 316L type of stainless steel is a popular steel material, as it has excellent corrosion resistance in aqueous solutions at ambient temperatures. However, the application of the AISI 316L stainless steel is limited by its relatively low hardness and low wear resistance. In this study, the electroless Ni–B coating was deposited on the AISI 316L stainless steel, and its structural, tribological and corrosion properties were characterised. Microstructural analysis showed that the electroless Ni–B coating deposited on the AISI 316L steel substrate exhibited a typical cauliflower-like structure exhibits an amorphous growth. From this study, it may be concluded that this process cannot only improve the hardness and wear resistance of the 316L stainless steel, but can also provide cathodic protection without losing or sacrificing the original properties of the 316L stainless steel.

Effect of micro-droplets on the local residual stress field in CAE-PVD thin coatings

The effect of surface defects on the residual stress local distribution in thin coatings has been investigated by an innovative high resolution methodology, which mainly consists of incremental focused ion beam (FIB) micron-scale ring-core milling (IμRCM), combined with high-resolution in situ SEM-FEG imaging of the relaxing surface and in-plane strain analysis by digital image correlation (DIC). The depth profile of the residual stress can be obtained from the experimentally measured surface strain with sub-micron spatial resolution (both lateral and in-depth) by using a finite element modeling (FEM) reverse calculation procedure. A chromium nitride (CrN) coatings was produced by Cathodic Arc Evaporation Physical Vapor Deposition (CAE-PVD) on AISI 316L steel substrate. Preliminary characterization of coatings consisted of nanoindentation testing, FIB cross section microstructural analysis and XRD (sin2ψ) average residual stress measurement. Local residual stress was measured nearby to surface micro-droplets, with the main aim of investigating the effect of such defects on the residual stress in-depth distribution. A series of stress measurements were also performed on the homogeneous defect-free coating. Significant differences were found in terms of residual stress and stress gradient in proximity of surface defects, in comparison with the residual stress measured on the defect-free areas. In case of micro-droplets, such differences were attributed to significant modification of growth mechanisms and microstructure of the coating, that lead to a different competitive mechanism of residual stress build-up. This assumption was supported by the microstructural FIB-SEM observation, which showed anomalous grain growth and changes in crystal orientation in correspondence of a droplet.

Deposition and characterization of magnetron sputtered amorphous Cr–C films

Thin films in the Cr–C system with carbon content of 25–85 at.% have been deposited using non-reactive DC magnetron sputtering from elemental targets. Analyses with X-ray diffraction and transmission electron microscopy confirm that the films are completely amorphous. Also, annealing experiment show that the films had not crystallized at 500 °C. Furthermore, X-ray spectroscopy and Raman spectroscopy show that the films consist of two phases, an amorphous CrCx phase and an amorphous carbon (a-C) phase. The presence of two amorphous phases is also supported by the electrochemical analysis, which shows that oxidation of both chromium and carbon contributes to the total current in the passive region. The relative amounts of these amorphous phases influence the film properties. Typically, lower carbon content with less a-C phase leads to harder films with higher Young’s modulus and lower resistivity. The results also show that both films have lower currents in the passive region compared to the uncoated 316L steel substrate. Finally, our results were compared with literature data from both reactively and non-reactively sputtered chromium carbide films. The comparison reveals that non-reactive sputtering tend to favour the formation of amorphous films and also influence e.g. the sp2/sp3 ratio of the a-C phase.

Low temperature Ti-Si-C thin film deposition by ion beam assisted methods

Thin, multiphase Ti-Si-C coatings were formed by IBSD or by IBAD methods on AISI 316L steel substrates in room temperature, using single Ti3SiC2 target. In those methods the TiXSiCY coatings were formed from the flux of energetic atoms and ions obtained by ion sputtering of the Ti3SiC2 compound sample. As sputtering beam the beam of Ar+ ions at energy of 15keV was applied. In the IBAD method the dynamically formed coatings were additionally bombarded by beam of Ar+ ions at energy of 15keV. The ion beams parameters were obtained by using Monte Carlo computer simulations. The morphology (SEM, TEM), chemical (EDS/EDX) and phase composition (XRD) examinations of formed coatings were provided as well as confocal Raman microspectroscopy. Analyzed coatings were relatively thin (150nm-1μm), flat and dense. XRD analysis indicated in amorphous TiSi, the traces of Ti5Si3 and other phases from Ti-Si-C system (TiSi, TiSi2,Ti3SiC2). For chemical bonds investigation, the laser beam with length of 532nm was used. Those analyses were performed in the low (LR) or in high (HR) resolution modes in room temperature and in 4000C. In the HR mode the spectral resolution was close to 2 cm−1. In Raman spectra peaks at: 152cm−1, 216cm−1, 278cm−1, 311 cm−1, 608cm−1, 691cm−1 were recorded. Nanoindentation tests were done on coated and uncoated substrates with diamond, Berkovich-type indenter. Vickers hardness HIT and reduced elastic modulus EIT were calculated using Olivier& Pharr method. HIT for coated substrates was in the range 2.7 to 5.3 GPa, EIT was 160 GPa.

Comparative study of hydroxyapatite and octacalcium phosphate coatings deposited on metallic implants by PLD method

The aim of the presented study was an analysis of two apatite coatings: hydroxyapatite (HA) and octacalcium phosphate (OCP) as coatings materials for metallic implants. Both layers were deposited by means of the PLD method. As a target material, synthetic, powdered and pressed hydroxyapatite was used. HA was deposited on 316L steel substrate in two temperature ranges for obtaining different coatings: 150±30°C and 430±30°C for OCP and HA, respectively. As an intermediate layer, the nanocrystalline diamond layer (NCD) was deposited. Examined calcium phosphate layers were tested for adhesion of osteoblast cell culture (MG-63). Analytical methods (AFM, FTIR) showed the usefulness of the PLD method for deposition of the apatite layers on metallic implants. Both examined layers showed biocompatibility with human osteoblast cells and presented favorable conditions for their proliferation.

Characteristics of Carbon Films Deposited by Magnetron Sputtering

Carbon thin films are often called in the literature, “diamond-like carbon” films. They consist of two basic allotropic forms of carbon, which are graphite and diamond. Carbon atoms with sp bonds form after deposition of a graphite-like phase. Atoms with sp bonds form a diamond-like phase. Diamond-like crystallites are built into a graphite-like phase matrix. In this paper there are presented experimental results of deposition of carbon films by the magnetron sputtering method and the results of analysis of the surface and phase structures of the deposited films. The amorphous carbon films were deposited from graphite targets on 316L steel substrates. The films were deposited at room temperature, in vacuum. The deposition time was 3 h; the depositions were conducted at two different distances between the substrate and the magnetron target.

Thermal stress analysis of Wc–Co/Cr–Ni multilayer coatings on 316L steel substrate during cooling process

In this study, a thermal stress analysis was performed in WC–Co/Cr–Ni multilayer coatings deposited on 316L steel substrate during the cooling process from 1273 K to room temperature. Firstly, the cooling curve of this coating system was measured by a thermocouple, experimentally. Then, this curve was considered for numerical analysis. With this regard, a transient thermal analysis was carried out using finite element method (FEM) utilizing ANSYS software. Thermal residual stresses were calculated for all system and were compared for different nodes selected in terms of concentrated stress areas on the model. The compressive and tensile stresses occurred in WC–Co/Cr–Ni coatings and 316L substrate owing to the different thermal expansion coefficients in each material, respectively. Additionally, the cooling curves determined from experimental and numerical studies are very similar to each other and the differences between them can be neglected.

Cross-sectional transmission electron microscopy study of phase transformations at TiN film/steel substrate interfaces

Cross-sectional transmission electron microscopy (XTEM) was used to investigate the extent of solid-state phase transformations near the interfaces of TiN films and AISI M50, 316L, and 440C steel substrates. An ion-plating system was used to deposit the TiN films with and without an initial Ti underlayer on the substrates, whose carbon concentrations ranged from 0.02 to 1 wt%. All films were produced at 500°C. XTEM, together with electron-energy-loss spectroscopy (EELS) and convergent-beam electron diffraction, of the interfaces indicated that (a) the ion-plated Ti underlayers transform into a TiC phase on high-carbon steel substrates and into a δ'-TiN phase on low-carbon steel substrates, and (b) without a Ti underlayer, TiN grows as the dominant phase on 440C steel substrates.