Surface Of 316L Stainless Steel Research Articles

Comparative Investigation on the Tribological Performances of TiN, TiCN, and Ti-DLC Film-Coated Stainless Steel

TiN, TiCN, and Ti-diamond-like carbon (DLC) films were coated on 316L stainless steel surfaces by physical vapor deposition. All films exhibited uniform and dense surfaces with good adhesion. The Ti-DLC film demonstrated the lowest surface roughness. TiC and free C were observed in both the TiCN and Ti-DLC films. Among the three films, the TiCN film demonstrated the highest hardness and elastic modulus, followed by the Ti-DLC film and finally the TiN film. Under dry conditions, all films exhibited significantly lower coefficients of friction than stainless steel. The Ti-DLC film showed the lowest coefficient of friction and is thus considered an ideal anti-wear material for orthodontic applications. The friction mechanisms of the three films were also compared. Therefore, this study provides experimental data and a theoretical basis that may guide the production and modification of dental braces.

Effects of temperature on corrosion performances of TiO2/SS316L in supercritical water for hydrogen production

Temperature is the most important factor for hydrogen generation during supercritical water gasification process. However, the increasing temperature could accelerate the corrosion of the reactor material, at the presence of oxygen, as less amount of oxygen can promote the hydrogen production. In this study, we prepared a 0.1 mm thick of TiO2 coating on the surface of 316L stainless steel (SS316L) to enhance the corrosion resistance of SS316L during hydrogen production process in supercritical water. The influences of temperature (400–500 °C) on surface morphologies and corrosion depth and rate of TiO2/SS316L were evaluated at 25 MPa with 1000 mg/L oxygen for 80h. Results showed that cracks and pores were present on the surface of TiO2/SS316L after corroded in SCW for 80h. The crack width and corrosion rate was aggravated at higher temperature. The remained thickness of the coating at 400 °C, 450 °C, 500 °C were 0.08 mm, 0.05 mm and 0.03 mm, respectively. NiO and NiFe2O4 were generated around the crack on the surface of TiO2/316L at 500 °C, the coating had a tendency to peel off the substrate.

Effects of CeO2 on the Microstructure and Properties of Laser Cladding 316L Coating

Laser cladding was used to distribute a CeO2-modified 316L powder coating onto a 316L stainless steel surface. The cladding layer phase composition was evaluated through x-ray diffraction. An analysis of the microstructure was conducted using an optical microscope and scanning electron microscope, while the micro-hardness was measured using a tester. The coating corrosion behavior in response to 3.5% NaCl solution was analyzed by polarization curves and electrochemical impedance spectroscopy. Finally, the overall performance of coatings with different CeO2 concentrations, 1, 2, and 3%, was compared. Results showed that adding CeO2 significantly refined the grains, reduced the coating porosity, and effectively limited the appearance of local corrosion. Also, additive CeO2 shifted the coating’s electrode potential in a positive direction, minimizing the current density of corrosion, creating a stable passivation film, and improving the coating’s corrosion resistance. The coating performance (hardness and corrosion behavior) was optimal when 2% CeO2 was employed as the powder mass.

Corrosion Resistance to Molten Zinc of a Novel Cermet Coating Deposited by Activated Combustion High-Velocity Air Fuel (AC-HVAF)

Molten zinc is very aggressive to austenitic stainless steels. In this study, a novel cermet coating consisting of FeB-12 wt.%Al0.25FeNiCoCr was deposited on the surface of 316L stainless steel to protect it from liquid zinc corrosion using activated combustion high-velocity air fuel (AC-HVAF). The microstructure and phase composition of the powders and coating were determined by scanning electron microscopy (SEM) with energy-dispersive x-ray spectroscopy (EDS) and x-ray diffraction (XRD) analysis. The thermal expansion coefficient, microhardness, thermal shock resistance, abrasive wear resistance, and corrosion resistance to molten zinc of the coating were investigated. The results showed that the first macrocrack appeared on the surface of the coating after 32 thermal shock cycles. Compared with the 316L stainless steel substrate, the abrasive wear resistance of the coating was twice as high. Also, the average corrosion rate of the FeB-12 wt.%Al0.25FeNiCoCr coating in molten zinc at 450 °C was 16.17 μm/day, much lower than the value of 115.44 μm/day for 316L stainless steel in molten zinc at 460 °C.

A Study of poly4-oxo-4-(4-sulfamoylphenylamino) but-2-enoic acid as a good anti – Corrosion of 316L stainless steel in 0.2M hydrochloric acid solution.

Poly4-oxo-4-(4-sulfamoylphenylamino) but-2-enoicacid (POSPAEA) was prepared by the electrochemical polymerization of 4-oxo-4-(4-sulfamoylphenylamino) but-2-enoicacid) (OSPAEA) monomer on 316L stainless steel as anti-corrosion coating. scanning electron microscope (SEM), Atomic Force Microscope (AFM) and Fourier transform infrared techniques (FTIR) were used to identify the structure of the polymer layer. also The corrosion behavior of uncoated and coated 316L stainless steel were estimated from Tafels plots using Potentiostatic technique in 0.2 M HCl solution as corrosion medium at temperature ranging (293 – 323) K. Nano materials such as graphene and ZnO Nano in different concentrations were added to monomer solution to improve the corrosion resistance of 316L stainless steel surface so that the results showed that the values of corrosion protection efficiency for coating polymer increase with adding Nano materials. In addition the kinetics and thermodynamics of parameter were calculated for corrosion process 316L stainless steel before and after polymer coating in the acidic medium.

Obtaining tailored surface characteristics by combining shot peening and electropolishing on 316L stainless steel

Abstract Shot peening is a well-established surface treatment commonly used to improve mechanical properties of material's surfaces. Studies have shown notable enhancement of fatigue strength, wear, scratch and corrosion resistance and fretting properties as a result of an intensive shot peening treatment, the so-called severe shot peening. Nevertheless, this process has some drawbacks including quite high surface roughness and possible embedment of shot residuals at the treated surface, which can have adverse effects depending on the final application. In this paper, electropolishing has been evaluated as a cleaning post-treatment for shot peened surfaces of 316L stainless steel. For this purpose, electropolishing voltage has been varied with the aim of obtaining clean and smoother surfaces without sacrificing the mechanical improvements produced by shot peening. The treated surfaces have been characterized considering surface roughness, morphology, wettability, residual stresses and microhardness evolution after various shot peening treatments combined with electropolishing using different parameter set-ups to identify the most promising combinations.

The Influence of Surface Wettability and Topography on the Bioactivity of TiO2/Epoxy Coatings on AISI 316L Stainless Steel.

Epoxy/TiO2/epoxy and epoxy/FAS-TiO2/epoxy coatings were applied to the surface of AISI 316L stainless steel with the aim to improve the biocompatibility and antibacterial properties. Contact-angle measurements were used to evaluate the wetting properties of the epoxy, epoxy/TiO2/epoxy and epoxy/FAS-TiO2/epoxy coatings. The epoxy and epoxy/TiO2/epoxy coatings were hydrophilic compared with the strongly hydrophobic epoxy/FAS-TiO2/epoxy coating. The average surface roughness (Sa) of the epoxy/FAS-TiO2/epoxy coating was higher than that of the epoxy/TiO2/epoxy coating due to the formation of agglomerates. The biocompatibility evaluation revealed that the cell attachment was significantly higher on the epoxy/FAS-TiO2/epoxy and epoxy/TiO2/epoxy coatings compared with the pure epoxy coating. We also observed improved antibacterial properties for the epoxy coatings with the addition of both TiO2 and FAS-TiO2 nanoparticles.

An Albumin Biopassive Polyallylamine Film with Improved Blood Compatibility for Metal Devices.

Nowadays, a variety of materials are employed to make numerous medical devices, including metals, polymers, ceramics, and others. Blood-contact devices are one of the major classes of these medical devices, and they have been widely applied in clinical settings. Blood-contact devices usually need to have good mechanical properties to maintain clinical performance. Metal materials are one desirable candidate to fabricate blood-contact devices due to their excellent mechanical properties and machinability, although the blood compatibility of existing blood-contact devices is better than other medical devices, such as artificial joints and artificial crystals. However, blood coagulation still occurs when these devices are used in clinical settings. Therefore, it is necessary to develop a new generation of blood-contact devices with fewer complications, and the key factor is to develop novel biomaterials with good blood compatibility. In this work, one albumin biopassive polyallylamine film was successfully established onto the 316L stainless steel (SS) surface. The polyallylamine film was prepared by plasma polymerization in the vacuum chamber, and then polyallylamine film was annealed at 150 °C for 1 h. The chemical compositions of the plasma polymerized polyallylamine film (PPAa) and the annealed polyallylamine film (HT-PPAa) were characterized by Fourier transform infrared spectrum (FTIR). Then, the wettability, surface topography, and thickness of the PPAa and HT-PPAa were also evaluated. HT-PPAa showed increased stability when compared with PPAa film. The major amino groups remained on the surface of HT-PPAa after annealing, indicating that this could be a good platform for numerous molecules’ immobilization. Subsequently, the bovine serum albumin (BSA) was immobilized onto the HT-PPAa surface. The successful introduction of the BSA was confirmed by the FTIR and XPS detections. The blood compatibility of these modified films was evaluated by platelets adhesion and activation assays. The number of the platelets that adhered on BSA-modified HT-PPAa film was significantly decreased, and the activation degree of the adhered platelets was also decreased. These data revealed that the blood compatibility of the polyallylamine film was improved after BSA immobilized. This work provides a facile and effective approach to develop novel surface treatment for new-generation blood-contact devices with improved hemocompatibility.

Magnetoelectropolishing treatment for improving the oxidation resistance of 316L stainless steel in pressurized water reactor primary water

The surfaces of 316L stainless steel with mechanical polishing (MP) or electropolishing (EP) in the presence of a magnetic field (MEP) before and after exposure to simulated pressurized water reactor (PWR) primary water were characterized by various techniques such as SEM, Raman spectroscopy, XPS and TEM measurements. The surface microhardness was lower and the surface roughness was higher for the as-treated MEP specimen than for the as-treated MP specimen. The oxide films that formed on the as-treated MP and MEP surfaces were nanometer-thick and rich in chromium. The Cr/(Fe + Ni) ratio of the as-treated MEP surface film was higher than that of the as-treated MP surface film. After exposure to simulated PWR primary water at 310 °C for 1050 h, a dark double oxide layer that was approximately 662 nm thick formed on the MP surface, while the MEP surface retained its original brightness as before exposure with a nanometer-thick oxide layer with a high Cr content. The MP and MEP specimens showed different oxidation kinetics when exposed to high temperature water. The high Cr/(Fe + Ni) ratio of the surface film on the MEP 316L SS contributed to its excellent oxidation resistance in simulated PWR primary water.

Surface and protein adsorption properties of 316L stainless steel modified by polyvinyl alcohol and plasma-treated polyvinyl alcohol films

In this study, we investigated the surface and protein adsorption properties of 316L stainless steels coated with polyvinyl alcohol (PVA) and N2-plasma-modified PVA films. The water contact angle of the 316L stainless steel significantly decreased after the coating with the PVA film owing to the abundant hydrophilic functional groups formed on the surface of the PVA film. The signal of the hydrophilic functional groups of the PVA film became more significant after the N2 plasma modification, leading to a further decrease in the water contact angle of the PVA film. Electrochemical tests showed that the corrosion resistance of the 316L stainless steel improved by the coating of the PVA and N2-plasma-modified PVA films. Bicinchoninic-acid protein assay results showed that the 316L stainless steels coated with the PVA and N2-plasma-modified PVA films exhibited lower bovine serum albumin concentrations than that of the neat 316L stainless steel, indicating that the anticoagulant properties of the 316L stainless steel surface could be improved after the coating with the PVA and plasma-modified PVA films.

Microstructure, corrosion and mechanical properties characterization of AISI type 316L(N) stainless steel and modified 9Cr-1Mo steel after 40,000 h of dynamic sodium exposure at 525 °C

This paper presents results of a comprehensive study on 316L(N) stainless steel (SS) and modified 9Cr-1Mo steel exposed to flowing sodium at 525 °C for 40,000 h in a bi-metallic (BIM) loop. A non-uniform ferrite layer of 8–14 μm thickness was formed on the surface of 316L(N) SS due to elemental leaching of Ni and Cr. Higher carbon activity (aC) in sodium resulted in carburization of 316L(N) SS with a surface carbon content of 0.5 wt.%. The effective carbon diffusion coefficient, DeffC was estimated to be 3.64 × 10 −19 m2/s. Consequent to carbon transport in 316L(N) SS, extensive sensitization was detected and the charge density, Pa, values for sodium exposed, thermally aged and carburized zone were found to be 23.3, 18.5 and 4.8 C/cm2, respectively. 42 and 60% decrease in percent total elongation (%TE) and percent reduction in area (%RA), respectively were observed in sodium-exposed 316L(N) SS, as compared to thermally aged specimen, due to surface carburization. Unlike 316L(N) SS, modified 9Cr-1Mo steel did not show carburization, however, it showed a decrease in the impact energy values due to the presence of Laves phase and M23C6 precipitates in sodium-exposed and thermally aged specimens.

316L stainless steel corrosion in molten salts NaNO3 KNO3 NaNO2 simulating storage conditions

A wide variety of stainless steel is used in concentrated solar plants in different elements as pipelines, pumps, storage tanks, among others, and these are in contact with molten salts, which are used as thermal energy transfer fluids. In this paper, corrosion of stainless steel AISI 316L in molten salt NaNO3 - NaNO2 - KNO3 has been investigated at temperatures of 450, 500 and 550°C, for an exposure period of 150 hours. The salt mixture is sprayed by spray onto the surface of 316L stainless steel, which has been preheated to 170°C. To obtain a thin layer of salt on the samples, these are carried to the furnace in the presence of an oxidizing atmosphere at high temperature for 1, 3, 10, 30, 100 and 150 hours. The results of mass gain and characterization by SEM-EDS and XRD of the surfaces showing the formation of a passive film, composed mainly of hematite Fe2O3. The thickening of the oxide film is according to a parabolic law, whose speed depends on the temperature of the melt.

Controlling chloride induced stress corrosion cracking of AISI 316L stainless steel by application of buffing

Abstract This paper presents the effect of buffing on the stress corrosion cracking (SCC) resistance of machined surfaces of AISI 316L stainless steel (SS). Surface finishing operations are known to lower the SCC resistance of austenitic stainless steels and yet are unavoidable. AISI 316L SS samples were given for different surface finishing operations like turning, milling and grinding. The surface roughness in each case was determined using stylus profiler (contact mode). Lattice strain and phase changes were detected by X-ray diffractometry (XRD) studies. SCC susceptibility has been studied before and after surface buffing operation by exposing to magnesium chloride hexahydrate solution (MgCl2.6H2o) as per ASTM standard procedure G36 for 3h. Microstructural characterization before and after SCC tests were characterize by using field emission SEM (FESEM). Results highlights that AISI 316L SS in turned, milled, and ground condition were highly prone to Cl– induced SCC. But on the application of buffing, the SCC resistance of the samples was enhanced and no cracking was observed. Crack enhancement was due to a) reduced surface roughness b) minimum plastic strain and c) high compressive residual stresses generated during buffing operation.

Microstructure, hardness and biocompatibility properties of ceramic based coatings produced by plasma spray method

Ceramic materials with excellent mechanical, corrosion and abrasion resistance is set in terms of features such as biomaterials. In this study, Al2O3, Al2O3-40% TiO2, ZrO2 - 8% Y2O3 and Cr2O3-2% TiO2 ceramic coatings were produced by plasma spraying on AISI 316L stainless steel surface. It was aimed to investigate microstructure, hardness and biocompatibility properties of coatings. Scanning electron microscope (SEM) analysis and X-ray diffraction (XRD) phase analysis were used to determine the microstructure and phase composition properties. The biocompatibility properties of coatings have been tried to be determined by analyzing cytotoxicity and viability. The SEM images show that the ceramic coatings are connected in accordance with the substrate. The XRD analyzes show the formation of binary and ternary complex phases in the coating layers. Cr2O3-2% TiO2 coating has the highest hardness in the coating layers. Biocompatibility tests reveal the most compatible and consistent results in terms of cytotoxicity were obtained with Al2O3-40% TiO2 coating.

Antibacterial TiCu/TiCuN Multilayer Films with Good Corrosion Resistance Deposited by Axial Magnetic Field-Enhanced Arc Ion Plating.

In order to develop a novel kind of antibacterial Cu-containing TiN film with good corrosion resistance, impressive mechanical properties, and low cytotoxicity, three differently designed multilayer films of TiCu/TiCuN multilayer (M1, M2, M3) were deposited on the surface of 316L stainless steel surface using the axial magnetic field-enhanced arc ion plating (AMFE-ARP) method, in which the interlayer of TiCu was first introduced for Cu-containing TiN film in order to improve comprehensive properties, especially the corrosion resistance of the film. The performance of the TiCu/TiCuN multilayer films was compared with that of the two single layers, TiN and TiCuN, which were deposited by the same method and the same total deposition time. The results indicated that the TiCu/TiCuN multilayer film of M2 revealed the best comprehensive corrosion resistance with low electric current values, high pitting potential, and high polarization resistance due to the proper thickness of TiCu interlayers and larger number of TiCu/TiCuN bilayers. In addition, the TiCu/TiCuN multilayer film of M2 also possesses comparable mechanical properties, excellent antibacterial and antibiofilm abilities, as well as good biocompatibility. Consequently, the antibacterial TiCu/TiCuN multilayer films with good corrosion resistance deposited by using the axial magnetic field-enhanced arc ion plating (AMFE-ARP) method are promising for application in biomedical antibacterial film for implants.

Influences of oxygen on corrosion characteristics of TiO2/316L stainless steel in supercritical water

Supercritical water gasification (SCWG) is a promising technology for converting organic wastes to hydrogen. Less amount of oxygen is beneficial for increasing hydrogen generation rate. However, the corrosion rate of reactor material would be accelerated. TiO2 coating with a thickness of 0.1 mm was prepared on the surface of 316L stainless steel (SS316L) to improve its corrosion resistance in supercritical water (SCW). The corrosion performances of TiO2/SS316L were tested in a bath SCW reactor at 400 °C, 25 MPa. The influences of oxygen concentration (0–1000 mg/L) on surface morphologies and corrosion depths were studied thoroughly. Results indicated that the surface of TiO2/SS316L exhibited cracks and pores after exposed in SCW. And the average corrosion rates accelerated at higher oxygen concentrations. The interface between the coating and medium was relatively smooth and there was no obvious change in the thickness of the coating with oxygen concentration of 0 and 500 mg/L. While for that with 1000 mg/L oxygen, the surface of TiO2/SS316L exhibited reticulate crack. The cross section showed a serrate structure, and only 0.08 mm thick of the coating was remained. In addition, the corrosion mechanism of coating was discussed.

Surface Modification by Combination of Dip-Pen Nanolithography and Soft Lithography for Reduction of Bacterial Adhesion

Dip-pen nanolithography (DPN) and soft lithography are techniques suitable to modify the surface of biomaterials. Modified surfaces might play a role in modulating cells and reducing bacterial adhesion and biofilm formation. The main objective of this study was threefold: first, to create patterns at microscale on model surfaces using DPN; second, to duplicate and transfer these patterns to a real biomaterial surface using a microstamping technique; and finally, to assess bacterial adhesion to these developed patterned surfaces using the cariogenic species Streptococcus mutans. DPN was used with a polymeric adhesive to create dot patterns on model surfaces. Elastomeric polydimethylsiloxane was used to duplicate the patterns and silica sol to transfer them to the medical grade stainless steel 316L surface by microstamping. Optical microscopy and atomic force microscopy (AFM) were used to characterize the patterns. S. mutans adhesion was assessed by colony-forming units (CFUs), MTT viability assay, and scanning electron microscopy (SEM). DPN allowed creating microarrays from 1 to 5 µm in diameter on model surfaces that were successfully transferred to the stainless steel 316L surface via microstamping. A significant reduction up to one order of magnitude in bacterial adhesion to micropatterned surfaces was observed. The presented experimental approach may be used to create patterns at microscale on a surface and transfer them to other surfaces of interest. A reduction in bacterial adhesion to patterned surfaces might have a major impact since adhesion is a key step in biofilm formation and development of biomaterial-related infections.

Investigation of nanoscale strains at the austenitic stainless steel 316L surface: Coupling between nanogauges gratings and EBSD technique during in situ tensile test

The understanding of the mechanical properties at the microstructure scale is a key factor for the material macroscopic behavior comprehension and its appropriate engineering at the scale of the structure. In this study, a new approach which is based on the combination of both nanogauges displacements monitoring and electron backscatter diffraction (EBSD) techniques performed under Scanning Electron Microscope (SEM) during in-situ tensile tests is proposed. Strain evolutions at the microstructure components and the behavior of the material can be compared to the crystallographic data. The approach was applied to austenitic stainless steel 316L specimen in order to bring a proof of concept and put into evidence its potential. Among the information of interest which can be obtained through this technique, one can cite the possibility to highlight the strain initiations in the vicinities of twins and their evolutions during the tensile test or to evidence the strain heterogeneities at the surface of the specimen and its influence over the elongations and rotations of the microstructure components, which tends to be reorganized in order to balance the mechanical stress. Besides, such heterogeneities can be expressed in terms of misorientations and quantified from the EBSD data. The twinning and slip activities can also be correlated to the hardening of the material thanks to this method of characterization. As for its interest for characterizing the plastic domain, the technique can show how some grains may activate more than one slip system. Finally, it has been here demonstrated how complementary and powerful the combination of these two techniques may be considered and how it may give access to a better understanding of the material microstructure properties.

Microstructure Analysis of Hydroxyapatite Coating on Stainless Steel 316L Using Investment Casting Technique for Implant Application

Osteoporosis and traffic accident are major factor that causes bone fracture in Indonesia. One of solution for the bones fracture treatment is by using fixation implant that has similar characteristics with the human bones. Stainless Steel (SS) 316L is one of biomaterial that has been used as an implant material due to its corrosion resistance, good biocompatibility, and excellent mechanical properties. However, the bioactivity properties of the material is needed to improve by coating it with hydroxyapatite (HA). In this research, HA was coated to the surface of 316L SS by using investment casting technique. A slurry of HA was poured into casting cavity surface prior to metal casting process, and then followed by sintering at temperatures of 850oC, 900oC, and 950oC. Characterization of HA coating layer on specimen surface was conducted by Optical Microscope, Scanning Electron Microscope (SEM), and Energy Dispersive X-Ray (EDX). Hardness of the samples was measured by Vickers Hardness Tester. Result of the experiment shows that the invvestment casting is successfully to coat the HA on the SS 316L surface. Pouring method produces HA layer with thickness (spongy and porous surface) in the range of 60 µm - 110 µm. The increasing of sintering temperature increases the hardness number of the surfaces, and affect the purity of HA, but it is not related to coating thickness. Optimum sintering temperature is obtained at 900oC which produces the best calcium and phosphate ratio. The investment casting method is found as a simple and non-expensive technique that can be used to coat HA powder to SS 316L that produces good properties and optimum crystallinity of HA that suitable for orthopedic implant application.

The interfacial interaction between isocyanate and stainless steel

The interfacial interactions between methylene diphenyl di-isocyanate (MDI) and polymeric MDI (PMDI) with 316L stainless steel have been studied in order to understand the adhesion properties of polyurethane based adhesives (containing free isocyanate groups) on metal surfaces. A thin (<5 nm) layer of MDI and PMDI was deposited on the surface of clean 316L stainless steel and then analysed by X-ray photoelectron spectroscopy (XPS) and time of flight secondary ion mass spectrometry (ToF-SIMS). By using density functional theory (DFT) methods for the interpretation of XPS data, the presence of specific interactions between the adsorbate and the substrate was established. The reaction between isocyanate and metal hydroxyl groups with the formation of urethane-like bonding with the metal was observed. The formation of hydrogen bonds between the isocyanate nitrogen and the hydroxyl groups and the formation of a nitrogen-metal double bond, as a consequence of the cycloaddition reaction between isocyanate and metal oxide, are also proposed.