Stainless Steel Films Research Articles

Effect of Films on In‐Mold Decoration and Microcellular Foaming Injection Molding Parts: Cell Structure, Surface, Warpage, and Mechanical Properties

ABSTRACTThe in‐mold decoration and microcellular foaming injection molding (IMD‐MIM) process was proposed to solve the apparent quality problem of polypropylene in microcellular foaming injection molding. Based on physical experiments and finite element simulation, stainless steel (ST) and polyethylene glycol terephthalate (PET) decorative films were selected for analysis, and the influence of the type and thickness of the decorative films on the cell structure, surface morphology, warpage deformation, and mechanical properties was revealed. The results show that the surface quality of the samples coated is significantly improved, and the asymmetric temperature field caused by the films changes the structure and distribution of the cells. The cell density on the coated side is higher than that on the non‐coated side, and the average cell diameter is smaller, and the foam core layer is shifted to the coated side. The warpage caused by ST film is larger, up to 2.836 mm. With the intervention of ST film and PET film, the impact properties of the samples have little change, but the tensile and flexural properties of the foamed samples have been effectively improved. The tensile strength increased by 28.6% and 25.9%, while the flexural strength increased by 28.6% and 28.1%, respectively. This study provides new insights into the comprehensive optimization of the structure and performance of polypropylene microcellular foaming materials and provides support for the development and application of lightweight materials in the future.

Insight into the effective electrocatalytic sulfide removal from aqueous solutions using surface oxidized stainless-steel anode and its desulfurization mechanism

The electrochemical oxidation of hydrogen sulfide (H2S) has shown its potential for the real application of H2S emission control in wastewater treatment. In this study, a surface corrosion treatment of stainless steel (SS) was optimized by regulate Ni content in the oxide film on the SS AISI 304 surface for sulfide removal. The X-ray photoelectron spectroscopy and linear sweeping voltammetry results indicated a higher Ni content in the oxide film of surface-oxidized stainless steel (SOSS) attributed to a higher sulfide removal potential. Sulfide removal experiment results showed that SS-150 (with 150 s anodic pretreatment) anodes achieved the highest Ni content of 69% with the best sulfide removal efficiency, i.e., 97% within 48 h, which increased by 20% compared to the untreated SS. This study also demonstrated a strategy for in situ removal of deposited sulfur on the anodes by cathodic treatment at −0.38 V vs. RHE to alleviate the common issue of sulfur passivation. Density functional theory (DFT) calculation revealed that NiOOH was the major active species in SS-150 oxide film for a faster sulfide removal rate. The study developed a SS surface modification process for Ni content regulation that contributed to better sulfide removal efficiency.

A silicon photoanode protected with TiO2/stainless steel bilayer stack for solar seawater splitting

Photoelectrochemical seawater splitting is a promising route for direct utilization of solar energy and abundant seawater resources for H2 production. However, the complex salinity composition in seawater results in intractable challenges for photoelectrodes. This paper describes the fabrication of a bilayer stack consisting of stainless steel and TiO2 as a cocatalyst and protective layer for Si photoanode. The chromium-incorporated NiFe (oxy)hydroxide converted from stainless steel film serves as a protective cocatalyst for efficient oxygen evolution and retarding the adsorption of corrosive ions from seawater, while the TiO2 is capable of avoiding the plasma damage of the surface layer of Si photoanode during the sputtering of stainless steel catalysts. By implementing this approach, the TiO2 layer effectively shields the vulnerable semiconductor photoelectrode from the harsh plasma sputtering conditions in stainless steel coating, preventing surface damages. Finally, the Si photoanode with the bilayer stack inhibits the adsorption of chloride and realizes 167 h stability in chloride-containing alkaline electrolytes. Furthermore, this photoanode also demonstrates stable performance under alkaline natural seawater for over 50 h with an applied bias photon-to-current efficiency of 2.62%.

Passive Film and Surface Modification of Stainless Steel

Passive Film and Surface Modification of Stainless Steel

Sputtered Stainless Steel on Silicon Photoanode for Stable Seawater Splitting in Photoelectrochemical Flow Cell

Photoelectrochemical (PEC) seawater splitting is a promising method for the direct utilization of solar energy and abundant seawater resources for hydrogen production. Photoelectrodes are susceptible to various ions in seawater and complicated competitive reactions, resulting in the failure of photoelectrodes. This paper proposes the design and fabrication of different sputtered stainless steel (SS) films deposited on silicon photoanodes, completely isolating the electrolytes and semiconductor substrate. Upon coupling with the PEC flow cell, the back-illuminated photoanode coated with 316 SS cocatalyst achieves stable operation for 70 h in natural seawater with a highly alkaline KOH (30 wt.%, 7.64 mol/L) electrolyte due to the remarkable protection effect of the substrate from stainless steel, while the PEC seawater splitting system achieves a record hydrogen production rate of 600 μmol/(h·cm2). An appropriate Ni/Fe ratio in the SS ensures remarkable oxygen evolution activity, while chromic oxide ensures the effective anticorrosion effect by adjusting the microenvironment of the photoanodes. Moreover, fabricating PEC flow cells with photoanodes coated with SS cocatalysts are a viable strategy for PEC seawater splitting.

Sputtering: An eco‐friendly technique to obtain polymer‐metal hybrids

AbstractAmong the methods commonly used to obtain polymer‐metal hybrids, sputtering has stood out for its ability to deposit thin films at room temperature. Another highlight is that it does not produce toxic gases or residues to the environment, making it an eco‐friendly solution. This work aimed to produce and characterize stainless steel (SS) films on acrylonitrile‐butadiene‐styrene (ABS) polymer using a magnetron sputtering with a direct current source. The ABS‐SS surface and interface, the ABS thermal behavior, and the film‐substrate adhesion quality were analyzed. The characterization techniques were atomic force microscopy and scanning electron microscopy to reveal the surface, x‐ray fluorescence spectroscopy to determine the chemical composition, and transmission electron microscopy to determine the phases on the ABS‐SS interface. The samples' thermal behavior was analyzed through thermogravimetry and differential scanning calorimetry. Method B from the ASTM D3359 standard qualitatively evaluated the film‐substrate adhesion. The characterizations showed that the ABS did not degrade significantly during SS deposition and that the sample had acceptable film‐substrate adhesion quality, making the technique and deposition parameters suitable for the obtention of this hybrid material.

A comparative study on passive films of Fe–11Cr stainless steel and Fe–20Mn–11.5Al–1.4C–5Cr lightweight steel

Fe–20Mn–11.5Al–1.4C–5Cr (wt%) lightweight stainless steel (LWSS) was found to have equivalent or better resistance to pitting corrosion than Fe–11Cr (wt%) stainless steel (SS). The desirable resistance to pitting corrosion of the LWSS alloy was attributed to the formation of protective passive film. On LWSS, an (Al,Fe,Cr)-oxide was formed, and on SS, a (Fe,Cr)-oxide was formed. The passive film of LWSS had a higher Cr + Al content than that of SS. In addition, compared to the passive film of SS, the passive film of LWSS was found to be thick and the concentration of point defects was also low.

Synthesizing Nanoporous Stainless Steel Films via Vacuum Thermal Dealloying

Vacuum thermal dealloying is a recently developed technique and was newly introduced to produce nanoporous metals, due to its intriguing advantages, i.e., preventing oxidation and producing no chemical waste, etc. Here, we report on the fabrication of nanoporous stainless steel films by vacuum thermal dealloying of sputtered stainless steel–magnesium precursor films. It was found that crack-free nanoporous stainless steel films can be successfully attained under a broad temperature range of 450–600 °C, with a dealloying time of 0.5–2 h. The resulting structure and ligaments were temperature- and time-dependent, and moreover, the condition of “600 °C + 2 h” generated the most homogeneous structure. Moreover, small amounts of residual Mg were found at pore sites in the resultant structures, suggesting that the dealloying was not fully complete.

A Stretchable, Transparent, and Mechanically Robust Silver Nanowire-Polydimethylsiloxane Electrode for Electrochromic Devices.

The application of flexible indium tin oxide (ITO-free) electrochromic devices has steadily attracted widespread attention in wearable devices. Recently, silver nanowire/poly(dimethylsiloxane) (AgNW/PDMS)-based stretchable conductive films have raised great interest as ITO-free substrate for flexible electrochromic devices. However, it is still difficult to achieve high transparency with low resistance due to the weak binding force between AgNW and PDMS with low surface energy because of the possibility of detaching and sliding occurring at the interface. Herein, we propose a method to pattern the pre-cured PDMS (PT-PDMS) by stainless steel film as a template through constructed micron grooves and embedded structure, to prepare a stretchable AgNW/PT-PDMS electrode with high transparency and high conductivity. The stretchable AgNW/PT-PDMS electrode can be stretched (5000 cycles), twisted, and surface friction (3M tape for 500 cycles) without significant loss of conductivity (ΔR/R ≈ 16% and 27%). In addition, with the increase of stretch (stretching to 10-80%), the AgNW/PT-PDMS electrode transmittance increased, and the conductivity increased at first and then decreased. It is possible that the AgNWs in the micron grooves are spread during PDMS stretching, resulting in a larger spreading area and higher transmittance of the AgNWs film; at the same time, the nanowires between the grooves come into contact, thus increasing conductivity. An electrochromic electrode constructed with the stretchable AgNW/PT-PDMS exhibited excellent electrochromic behavior (transmittance contrast from ~61% to ~57%) even after 10,000 bending cycles or 500 stretching cycles, indicating high stability and mechanical robustness. Notably, this method of preparing transparent stretch electrodes based on patterned PDMS provides a promising solution for developing electronic devices with unique structures and high performance.

Mapping the Accouterment Effects of Plasma Nitriding on AISI 316L in Biomedical Applications

The present study aimed to critique the corrosion resistance of plasma-nitrided films of AISI 316L stainless steel with regards to their biomedical applications. The plasma nitriding process improves austenitic stainless steel’s micro-hardness and corrosion resistance. Austenitic stainless steel was treated at a temperature of 470 °C for 12, 24, and 36 h, to observe the outcomes of plasma nitriding. The corresponding microstructure, microhardness, depth of the nitrided layer, and electrochemical parameters were systematically characterized. The corrosion resistance of the plasma-nitrided specimens was gauged using the weight loss method in simulated body fluids (Phosphate-buffered saline (PBS), saline water, and ringer solution) by static immersion for 9, 18, and 27 days. Optimization was catalogued using the Taguchi method L27 orthogonal array to determine the optimum combination of plasma nitriding time and immersion time in simulated body fluid. The material characterization showed that the corrosion resistance of the plasma-nitrided specimens improved with longer nitriding times by Tafel polarization curves. Microhardness was observed at 12, 24, and 36 h as 1060, 1150, and 1220 HV0.1. SEM, with an energy-dispersive X-ray analysis (EDS) used to characterize the surface before and after plasma nitriding testing. It was concluded that CrN, which precipitates during processing and contributes to the loss of chromium from the surrounding matrix and the onset of a corrosive environment, is the primary cause of this behaviour.

Functional performance of thin Ag, SS, and Ti films on retro-reflective fabrics

Retro-reflective materials are gradually increasing in popularity and use due to their safety properties, and aesthetic advantages. This study details an experimental procedure of the functional performance of silver (Ag), stainless steel (SS), and titanium (Ti) coatings of 150 nm in thickness on retro-reflective fabrics (with plain, twill and diamond weave structures) via magnetron sputtering. The deposited thin films were characterised using CIE L* a* b* values, SEM, contact angle, air permeability, thermal conductivity, anti-static, IR and UV protection. The results reveal that Ag coated fabric can transfer away body heat, hence ensuring a feeling of coolness. The Ag coated fabric samples have an overall good infrared (IR) protective property followed by SS, with Ti having a poor IR protective performance. All of the coated fabrics show excellent ultraviolet protection with 50+ UPF ratings. Furthermore, the coated fabrics have good anti-static properties which prevent the build-up of static charge that can cause discomfort to the wearer, especially in dry weather conditions. The deposition of Ag, SS or Ti nanoparticles on the surface of the fabric increases the hydrophobicity of the material or results in a fabric with low wettability as evident from the measured contact angles.

Towards understanding Shewanella algae-induced degradation of passive film of stainless steel based on electrochemical, XPS and multi-mode AFM analyses

The degradation of the passive film of stainless steel caused by Shewanella algae was investigated through electrochemical tests, X-ray photoelectron spectroscopy and atomic force microscopy (AFM). The dynamic mode and the nano manipulation mode of AFM were adopted to obtain the 3D topography of cell/passive film interfaces and to manipulate cell movement, respectively. The surface Volta potential scanning by tapping-amplitude modulation mode and the conductivity tests by PeakForce-TUNA mode of AFM revealed the electron injection phenomenon from S. algae cells into adjacent passive film, which promoted the reduction of Fe3+ compounds and accelerated the degradation of passive film.

An improved multiphase SPH algorithm with kernel gradient correction for modelling fuel–coolant interaction

Fuel–coolant interaction (FCI) has a pivotal role in the development of core disruptive accident in a sodium-cooled fast reactor. The drastic deformation of multiphase interface in the FCI is hard to deal with in the traditional grid method. In this paper, an improved multiphase smoothed particle hydrodynamics (SPH) algorithm corrected with the kernel gradient correction (KGC) technique is presented for multiphase flow with a large density ratio and complex interfacial behaviors. The density discontinuity across the multiphase interface is described with the use of special volume, which only depends on the position information of adjacent particles. This multiphase SPH algorithm, which is troubled by an unstable and mixed-interface problem under a large density ratio, is significantly improved with the KGC technique. The accuracy and robustness of the improved method are demonstrated in the numerical simulations of the deformation of a square droplet, Rayleigh–Taylor instability, and bubble rising in water. The verified corrected multiphase SPH is applied to simulate the hydrodynamic behaviors of the general FCI and the interaction between fuels coated with stainless steel film and coolant. Boundary layer stripping, Rayleigh–Taylor instability, and Kelvin–Helmholtz instability are observed as important mechanisms of hydraulic fracturing. The fragments’ distribution and the influence of stainless steel film are analyzed. The existence of a stainless steel film has been shown to inhibit breakage.

Composite-fabric-based structure-integrated energy storage system

A structure-battery-integrated energy storage system based on carbon and glass fabrics is introduced in this study. The carbon fabric current collector and glass fabric separator extend from the electrode area to the surrounding structure. This system provides stable and high electrochemical performance under the mechanical loading of the composite structural battery. A thermoplastic tape melted into the fabrics separates the battery and structural parts to prevent penetration of epoxy into the battery part during autoclave molding and leakage of liquid electrolyte. Furthermore, a stainless-steel film blocks moisture penetration in the direction of the thickness. The electrochemical characteristics and mechanical stability of the structural battery were evaluated using a galvanic cell tester. The initial capacity of the structural battery was approximately 125 mAh/gLFP, and it exhibited steady cycling characteristics with a capacity of 110 mAh/gLFP for up to 50 charging/discharging cycles. The structure-integrated battery exhibited an energy density of over 25 Wh/kgstr, stable electrochemical performance, and load-bearing characteristics even when some of the battery components were subjected to tensile strain beyond the 1% level.

Enhanced Crevice Corrosion of Stainless Steel 316 By Degradation of Cr-Containing Hollandite Crevice Former

The disposal of high-level nuclear waste (HLW) is an important societal problem. It is also an extremely challenging corrosion research topic due to the highly complicated waste chemistry, long lasting radiation effect, and inevitable exposure to aqueous environments for hundreds of thousands of years. To safely accommodate some critical radionuclides such as volatile 129I and strongly heat generating 137Cs, numerous crystalline ceramic waste forms have been created and studied. Among the promising nuclear waste forms, hollandite was developed to isolate Cs waste and the corresponding decay product Ba due to the open tunnel structure capable of accommodating mono- or divalent cations. In this study, the synergistic corrosion interactions between a Cr-containing hollandite (Ba1.15Cr2.3Ti5.7O16) and stainless steel (SS) 316 is explored. This is relevant to the permanent disposal of HLW involving the encasement of glass or crystalline ceramic waste forms containing immobilized radionuclides in a metallic canister made from corrosion resistant alloys such as SS. The experiments performed in this study simulate the potential corrosion interactions occurring at the interface of the SS and ceramic. After corroding the SS316 and Cr-containing hollandite in proximity in 0.6 M NaCl at 90 oC for 28 days, severe crevice corrosion was identified on the surface of the SS, as evidenced by the presence of large pits and crevice damage with diameters of hundreds of microns. Similarly, localized damage was also found at matching sites on the Cr-hollandite surface, indicating interactions between the two materials. The synergistic corrosion interaction was likely due to the continuous release of Cr3+ cations from both materials, including the passive dissolution of the SS and the heterogenous degradation of the Cr-hollandite. The extra Cr3+ cations originated from the hollandite reduces the incubation time required to reach the critical crevice solution condition, thereby accelerating the breakdown of the passive film of SS and the subsequent onset of active dissolution. An adapted crevice corrosion model is applied to quantitively explain the accelerated corrosion of SS observed in this study.

Single-cell level investigation of microbiologically induced degradation of passive film of stainless steel via FIB-SEM/TEM and multi-mode AFM

The degradation of passive films of a stainless steel by S. algae was investigated at the single-cell level. The focused ion beam-scanning/transmission electron microscopy showed that the passive film underneath the adherent S. algae cell was significantly thinner than that without bacterial coverage after 3 days of inoculation. Atomic force microscopy (AFM) in the nano manipulation mode was used to move the bacterial cell and AFM in the dynamic mode revealed the nanoscale corrosion pit underneath. Peak force tapping-frequency modulation mode of AFM showed high Volta potentials at the pit center and low Volta potentials around the bacterial cell.

THz Filters Made by Laser Ablation of Stainless Steel and Kapton Film.

THz band-pass filters were fabricated by femtosecond-laser ablation of 25-m-thick micro-foils of stainless steel and Kapton film, which were subsequently metal coated with a ∼70 nm film, closely matching the skin depth at the used THz spectral window. Their spectral performance was tested in transmission and reflection modes at the Australian Synchrotron’s THz beamline. A 25-m-thick Kapton film performed as a Fabry–Pérot etalon with a free spectral range () of 119 cm, high finesse , and was tuneable over ∼m (at ∼5 THz band) with tilt. The structure of the THz beam focal region as extracted by the first mirror (slit) showed a complex dependence of polarisation, wavelength and position across the beam. This is important for polarisation-sensitive measurements (in both transmission and reflection) and requires normalisation at each orientation of linear polarisation.

Corrosion and Contamination of 316L Stainless Steel in Simulated HNO3-Based Spent Nuclear Fuel Reprocessing Environments with Cesium and Strontium

Austenitic 316L stainless steel is usually used as the structural material in spent fuel reprocessing facilities. However, the contamination of fission products from spent fuel (especially Cs and Sr) on the surface of facilities will greatly affect its safe decommissioning. In this study, for the first time, with the combination of characterizations of electrochemistry and laser-induced breakdown spectroscopy with two channels, the corrosion and contamination of 316L stainless steel were analyzed in simulated reprocessing environments with HNO3 concentrations of 3, 6, 8, and 12 M HNO3 containing Cs and Sr for 7, 14, 21, 30, and 60 days, respectively. The stability order of the passive film of 316L stainless steel in various environments was 12 M HNO3 > 8 M HNO3 > 3 M HNO3 > 6 M HNO3. Combined with other characterization methods, a mechanism was proposed. It was found that SrCO3, in the matrix, was the main contaminant in the initial 7 days in all environments due to a large number of holes. Then, the dissolution of contaminated steel surface led to the decrease of contaminant, and recontamination occurred after the repassivation of steel. These findings have significant implications for the development and selection of decontamination technology for the contaminated facilities made of 316L stainless steel.

Effect of trace water in ammonia on breaking passive film of stainless steel during gas nitriding

The dense passive film on the surface of austenitic stainless steel isolates the corrosion medium from the matrix, which makes it have excellent corrosion resistance. However, it also hinders the penetration and diffusion of nitrogen atoms in the process of gas nitriding. During gas nitriding of stainless steel, we found a very interesting phenomenon. When trace water in ammonia is at a certain threshold, ammonia, water, and chromium oxide passivation film will undergo gas-solid reaction to break the passivation film on the surface of stainless steel. The results show that the trace water content in ammonia during gas nitriding is very important for in-situ breaking of passive film. When the trace water content exceeds the upper threshold, oxidation will occur on the surface of stainless steel. On the other hand, when the trace water content is lower than the lower threshold, the passivation film hinders the diffusion of nitrogen atoms, and the nitride layer cannot be obtained. The mechanism of in-situ removal of passive film by trace water during gas nitriding of stainless steel is revealed for the first time, which provides a new idea and method for the study of surface modification of stainless steel by gas nitriding.

Application of Magnetoelectropolishing on the Oxidation Resistance Improvement of Stainless Steel Cladding in High-Temperature Water

Mechanical polishing (MP), electropolishing (EP), and magnetoelectropolishing (MEP) were applied on 308L stainless steel (SS) weld cladding. The surface characteristics after surface treatment and the oxides after immersion in the primary water of a pressurized water reactor were studied. XPS results showed that the passive film of surface-treated MEP 308L SS had higher Cr/(Ni+Fe) than MP and EP 308L SS, and reported surface-treated MEP 316L SS. Transmission electron microscopy results showed that duplex-layer oxide films consisted of Fe-rich spinel outer crystals and Cr-rich inner layers were formed on all surface-treated 308L SS cladding after immersion. The inner oxide layers on austenite were Cr-rich spinel dominant oxides and much thicker than the chromia-dominant oxides on ferrite. MEP decreased the inner oxide layer thickness on austenite of oxidized 308L SS. The oxidation resistance of the ferrite matrix with higher Cr content was not obviously impacted by surface treatment. A higher Cr/(Ni+Fe) in the preformed passive film on the austenite was mainly responsible for the better oxidation resistance of MEP 308L SS cladding. The improvement of oxidation resistance by MEP on dual-phase 308L SS cladding was different from that on single-phase 316L SS, suggesting that a local heterogeneous passive film on surface-treated MEP 308L SS was more likely degraded to a duplex-layer oxide film compared to the single-layer one on MEP 316L SS.