SUS304 Stainless Steel Substrate Research Articles

Superhydrophobic Ni nanocone surface prepared by electrodeposition and its overall performance

This study investigated the electrodeposition of a three-dimensional nanocone-shaped surface structure on SUS304 stainless steel substrates. Different electrodeposition parameters were adopted to generate nanocone-shaped Ni coatings. A detailed description of the coating microstructure and composition is proposed to understand how Ni nanocones develop throughout electrodeposition. A series of wetting tests compared the superhydrophobicity of the Ni nanocone coating. Wear tests were used to verify their mechanical stability. The best superhydrophobic and mechanical performance is achieved after 25 min electrodeposition, where the newly formed Ni nanocones grow to provide additional air cushion to support surface water droplets and promote wear resistance. The superhydrophobic Ni coating also has good anti-icing properties. Water droplets begin to freeze from the contact points between the water and the sample surface. Surface damage, such as scratches and holes, reduces superhydrophobic samples' anti-icing properties.

Đặc tính cơ học của các lớp phủ AlTiN, TiAlN lắng đọng bằng phương pháp hồ quang cathode (ARC-PVD) trên nền thép không gỉ SUS304

The aim of the paper was to investigate the mechanical properties of AlTiN, TiAlN coatings deposited by the arc-PVD method on SUS304 stainless steel substrate. The coating's surface morphology and structure were examined using a profilometer, scanning electron microscopy, energy dispersion spectroscopy and X-ray diffraction. Adhesion of the deposited coatings was determined by the Rockwell test. The sliding wear resistance of AlTiN and TiAlN was much higher than that of the stainless steel sample. The deposition of PVD film on a stainless steel substrate reduces the coefficient of friction by 3-6 times. The sliding wear mechanism of AlTiN and TiAlN coatings was different, AlTiN - the vertices of the coating were obtused, grooved, and scratched along the wear, with less material displacement in both directions along the wear trace; TiAlN - the coating was strongly plowed, the material was worn and forced in both directions of the sliding wear trace.

Investigation of mechanical and tribological properties of super-thick DLC films with different modulation ratios prepared by PECVD

Thick films can effectively improve the load-carrying capacity, but the thickness of films often fails to meet the requirements due to internal stress and other factors. The design of the multilayer film achieves an increase in film thickness by effectively reducing internal stress. The performance and structure of the super-thick DLC film can be structurally optimized by changing the modulation ratio. The super-thick DLC films consisting of Six-DLC layer (low Si content) and Siy-DLC layer (high Si content) with different modulation ratios (deposition time ratio of the Six-DLC to Siy-DLC) were successfully deposited on SUS304 stainless steel substrates by plasma enhanced chemical vapor deposition. The effect of modulation ratio on mechanical and tribological properties of the DLC-coating stainless steel was investigated by nano-indentation, scratcher and ball-on-disc reciprocating friction test. The results showed that hardening and toughening have been achieved through the modulation ratio design, and particularly remarkable when the modulation ratio ranges from is 1:5 to 1:1. The super-thick DLC film with a modulation ratio of 2:1 shows the best adhesion strength. Moreover, a film with a modulation ratio of 1:2 exhibits low COF about 0.03 at a load of 5 N due to the Si-rich transfer layer between the sliding interfaces; once the load reaches 20 N, the friction coefficient cannot establish such a low friction interface between the tribopairs, which is related to the peeling of the Si-rich transfer layer caused by high contact stress.

Microstructure, mechanical and tribological properties of DLC/Cu-DLC/W-DLC composite films on SUS304 stainless steel substrates

Besides their direct use as functional coatings, metal doped diamond-like carbon (Me-DLC) films are also adopted as buffer layers of DLC films to help reducing residual stress or improving adhesion to the substrates. However, single Me-doped buffer layer often deteriorates some of the inherent excellent mechanical properties of DLC films. In this paper, composite DLC films with double buffer layer based on W-DLC and Cu-DLC thin films were deposited on stainless steel (SS) substrates using microwave electron cyclotron resonance chemical vapor deposition (ECR-CVD) method combined with magnetron sputtering method, forming a film structure of DLC/Cu-DLC/W-DLC/SS. The composite films with this film structure show very smooth surface morphology, and possess high hardness (35 GPa) and low friction coefficient (0.14, friction pair: GCr15, HRC60) at the same time. It was also shown in this work that the sputtering current of the W target when depositing the most inner W-DLC layer can affect the formation of the sp3 bond in the composite film, which has great influence on the mechanical properties of the composite films. With different sputtering current, the hardness of the composite films can go up to 35 GPa, or go down to 14 GPa, resulting in different wear resistance against GCr15 friction pair.

Study on the Performance of Nano-Titanium Nitride-Coated Stainless Steel Electrodes in Electro-Fenton Systems.

The electro-Fenton (EF) process is a type of electrochemical oxidation process; ·OH radicals are generated on the cathode using electricity and decolorize dye wastewaters. Most studies on EF systems in the past have focused on the operating parameters of this process. In recent years, the influence of electrode performance on the EF process has begun to receive more attention. In this study, direct nitridation was used to prepare titanium nitride powders, which were thereafter coated on an SUS304 stainless steel substrate. The performance of this system in the treatment of rhodamine B dye wastewaters via the EF process was investigated. The experimental methods used in this work include: (1) scanning electron microscopy (SEM); (2) X-ray diffraction (XRD); (3) electrochemical Tafel curves; (4) linear sweep voltammetry (LSV); (5) and cyclic voltammetry (CV). It was shown that high-purity TiN can be formed at nitriding temperatures above 900 °C, and the strength of the (111) crystal plane increases with the increase in nitriding temperature; the TiN coating effectively activates the reactive surface of the electrode owing to its porous structure. In terms of corrosion resistance, the corrosion potential and corrosion current of the TiN 1000 °C/SUS304 electrode were 116.94 mV and 205 nA/cm2, respectively, and the coating had a coating porosity of 0.89 × 10−7. As compared with SUS304 stainless steel, the TiN 1000 °C/SUS304 composite electrode had a significantly greater degree of corrosion resistance and exhibited higher redox activity in LSV tests. This composite electrode could achieve a decolorization rate of 49.86% after 30 min, and 94.46% after 120 min. In summary, the TiN 1000 °C/SUS304 composite electrode is very stable and has excellent decolorization efficacy in the EF process. Our findings will serve as a useful reference for future studies on EF electrodes.

Adhesion of SiO2 thin films to plasma-treated SUS304 stainless steel substrates

ABSTRACTThe adhesion strength of the coated SiO2 thin film to SUS304 stainless steel substrates with various surface treatment conditions is studied in this research. The surface of the SUS304 stainless steel substrate is first treated with 1000-W plasma and then a SiO2 thin film is deposited onto the surface via radio-frequency magnetron sputtering. Scanning electron microscopy is employed to observe the surface and cross section of the coating and X-ray diffraction is used to analyze the crystallographic structure. Moreover, a nanoscratch test instrument was employed to examine the indentation, scratches, coating hardness, modulus of elasticity, coefficient of friction, and critical adhesion of the SiO2 film and to obtain surface profiles. A comparison of the coating adhesion of the substrate surfaces with and without plasma treatment indicates that critical adhesion increases significantly after Ar/N2/O2 plasma treatment.

Antimicrobial properties of Zr–Cu–Al–Ag thin film metallic glass

Metallic glass as a prominent class of structure and multifunctional materials exhibits several unique properties in mechanical, electrochemical, and thermal properties. This study aimed to realize the advantage of biomedical application and to promote the attainable size of metallic glasses by the physical vapor deposition. The Zr–Cu–Al–Ag thin film metallic glass (TFMG) was deposited on silicon wafer and SUS304 stainless steel substrates by magnetron sputtering with single target. For X-ray diffraction analysis, all TFMGs revealed typical broad peaks around the incident angle of 30 to 50°, suggesting that coatings possess amorphous structure. In addition, diffuse halo ring patterns of transmission electron microscopy indicated a fine amorphorization for TFMG via sputtering process. The variation of surface roughness showed that TFMG derived from higher power of metallic targets revealed rougher morphology. Besides, the roughness of SUS304 stainless steel substrate significantly reduced from 7nm to about 1nm after TFMGs were deposited.The microbes of Candida albicans, Escherichia coli, and Pseudomonas aeruginosa were used and cultivated on the TFMG coatings with medium to investigate the antimicrobial properties. In the incubation experiment, the growth of each microbe was recorded by a digital photography system and the growth area was calculated by image processing software. The growth area of the microbes on the TFMG was mostly smaller than that on SUS304 stainless steel ones within incubation time of 72h, indicating that the TFMGs reveal better antimicrobial capability. Moreover, the coatings exhibit a particularly long-term antimicrobial effect for P. aeruginosa. In summary, the Zr–Cu–Al–Ag prepared by sputtering with a single target device presented superior glass forming ability, and coatings with copper and silver constituents revealed significantly antimicrobial properties. Besides, the surface roughness is another factor to affect the biological activities, suggesting that microbes are difficult to attach and move on an ultra-smooth surface. It is demonstrated in this study that the TFMGs extend attainable size of the metallic glass and show a potential application in medical related field.

Ti-containing hydrogenated carbon films fabricated by high-power plasma magnetron sputtering

To improve the characteristics of a diamond-like carbon (DLC) film, Ti-containing amorphous hydrogenated carbon thin films were deposited on sus304 stainless steel substrates by high-power plasma-sputtering with titanium metal as the solid plasma source in a mixed ArC2H2 atmosphere. The films were fabricated to obtain a multilayered structure of Ti/TiC/DLC gradient for improving adhesion and reducing residual stress. The effects of substrate bias and target-substrate distance on the films' properties were studied by glow discharge spectroscope, X-ray diffractometer, Raman spectroscope, nanoindenter, and a pin-on-disk tribometer. The results indicate that the films possess superior adhesive strength and toughness.

Preparation of Fe/Cr doped SiO2 thin film on 304 stainless steel substrate originated from corrosion

A Fe/Cr doped SiO2 thin film which can improve the anticorrosion characteristic of materials was prepared on SUS304 stainless steel substrates by a modified hydrothermal method that constitutes a two part preparation process. The corrosion of stainless steel and the dissolution of silica from Na–Ca glass are simultaneously stimulated by an aqueous lithium bromide solution, and then a Fe/Cr doped SiO2 thin film is coated onto the substrate. The Fe/Cr doped SiO2 film was characterised by scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and electron probe X-ray microanalyser. The results showed that the corrosion products and the silica are combined to form a Fe/Cr doped SiO2 thin film. Furthermore, a chemical bond is formed between the silicon coating and the metal that improves the compactness and the adhesive property of the film. The anticorrosion characteristics of the film were measured by the methods of weight loss and electrochemical potentiodynamic polarisation, indicating that the Fe/Cr doped SiO2 thin film can improve the anticorrosion performance of stainless steels effectively.

Preparation of Fe/Cr doped SiO2 thin film on 304 stainless steel substrate originated from corrosion

A Fe/Cr doped SiO2 thin film which can improve the anticorrosion characteristic of materials was prepared on SUS304 stainless steel substrates by a modified hydrothermal method which constitutes two parts of preparation process. The corrosion of stainless steel stimulated by aqueous Lithium bromide solution and the dissolution of silica from Na–Ca glass simultaneously. And then a Fe/Cr doped SiO2 thin film is coated onto the substrate. The Fe/Cr doped SiO2 film was characterised by scanning electronic micrographs, X-ray diffraction, X-ray photoelectron spectroscopy and Electron probe X-ray microanalyser. Results showed that the corrosion products MX+, M(OH)x+ (M: metal) and the silica reticular are combined to form a Fe/Cr doped SiO2 thin film. Furthermore, a chemical bond formed between silicon reticular and metal ions to improve the compactness and the adhesive property of the film. The anticorrosion characteristics of the film were measured by the methods of weight loss and electrochemical potentiodynamic polarisation, indicating that the Fe/Cr doped SiO2 thin film can improve the anticorrosion performance of stainless steels effectively.

Interfacial fracture characteristic and crack propagation of thermal barrier coatings under tensile conditions at elevated temperatures

Thermal barrier coatings (TBCs) have been extensively used in aircraft engines for improved durability and performance for more than fifteen years. In this paper, thermal barrier coating system with plasma sprayed zirconia bonded by a MCrAlY layer to SUS304 stainless steel substrate was performed under tensile tests at 1000°C. The crack nucleation, propagation behavior of the ceramic coatings in as received and oxidized conditions were observed by high-performance camera and discussed in detail. The relationship of the transverse crack numbers in the ceramic coating and tensile strain was recorded and used to describe crack propagation mechanism of thermal barrier coatings. It was found that the fracture/spallation locations of air plasma sprayed (APS) thermal barrier coating system mainly located within the ceramic coating close to the bond coat interface by scanning electron microscope (SEM) and energy dispersive X-Ray (EDX). The energy release rate and interface fracture toughness of APS TBCs system were evaluated by the aid of Suo–Hutchinson model. The calculations revealed that the energy release rate and fracture toughness ranged, respectively, from 22.15 J m−2 to 37.8 J m−2 and from 0.9 MPa m1/2 to 1.5 MPa m1/2. The results agree well with other experimental results.

Microstructure, corrosion behavior, and microhardness of plasma-sprayed W–Ni composite coatings

Commercial tungsten powder of average particle size 12 μm was mixed with 10 wt% Ni powder and plasma sprayed on a SUS304 stainless steel substrate. W–Ni composite coatings have been sprayed at different Ar plasma gas flow rates of 120, 150, and 170 l/min and different Ar carrier gas flow rates of 5, 8, and 10 l/min. The microstructure and phase structure of the sprayed coatings were investigated using a scanning electron microscope (SEM), X-ray diffraction (XRD), and an energy dispersive spectrometer (EDS). Corrosion tests were performed for the sprayed W–Ni coatings in a 3.5% NaCl solution using an electrochemical polarization method. It was found that the W–Ni coatings sprayed at a higher Ar gas flow rate showed higher corrosion resistance compared with coatings sprayed at a lower gas flow rate. A more positive value of the corrosion potential and a lower value of the corrosion current are observed for coatings sprayed at a higher Ar gas flow rate.

Macro-Residual Stress in 304 Stainless Steel Coated with ZrO<sub>2</sub>-CeO<sub>2</sub> Thin Films by Sol-Gel Process

X-ray diffraction (XRD) method to measure the residual stress existing in the metal substrate surface layer was introduced and the sol-gel ZrO2-CeO2 thin film was successfully prepared on SUS304 stainless steel substrate by dip-coating process. The macro residual stress existing in metal substrate was analyzed by XRD. It turns out that the compressive stress existing in the metal substrate surface layer increases with the increase of heat-treated temperature. Based on the above study, colored stainless steels of high quality were prepared by sol-gel process.

Study on the Macro-Residual Stress of 304 Stainless Steel Coated with TiO<sub>2</sub>-SiO<sub>2</sub> Thin Films by Sol-Gel Process

X-ray diffraction (XRD) method to measure the residual stress in the metal substrate surface layer and the medial oxide layer between thin film and metal substrate was introduced and the sol-gel TiO2-SiO2 thin film was successfully prepared on SUS304 stainless steel substrate by dip-coating process. The macro residual stress existing in metal substrate was analyzed by XRD. It turns out that the compressive stress existing in the metal substrate surface layer decreases with the raising of heat-treated temperature and that the compressive stress of metal substrate surface layer and the tensile stress of the medial oxide layer increase with the increase of the withdrawal speeds of the sol-gel dip-coating. Based on the above study, colored stainless steels of high quality were prepared by sol-gel process for the first time.

Determination of Interface Fracture Toughness in Thermal Barrier Coating System by Blister Tests

The theoretical model for the blister test method was used to analyze the interface fracture toughness of zirconia coating deposited on an SUS304 stainless steel substrate by a plasma-spraying method. The elastic parameters of the debonded coating were determined by testing the oil pressure q and maximum deflection w(0). SEM observation, compliance method and ultrasonic detection were used to determine the radius of the debonded coating. The three methods gave the same results for the debonded coating radius. Micro-observations showed that the interfacial crack propagates by the growth of voids or microcracks ahead of the main crack and coalescence with the main crack. The energy release rate G0 with phase angle ψ=0 for type A coating and type B coating was, respectively, 14.54∼25.88J/m2 and 11.88∼16.21J/m2. The corresponding interface fracture toughness for type A TBC coating and for type B TBC coating is, respectively, 0.77∼1.02MPas˙m1/2 and 0.52∼0.61MPas˙m1/2. The stable phase angle was approximately −31.5° and −30.2° for coating A and coating B, respectively.

ＬＰＤ法による金属基材へのＳｉＯ２薄膜の作製

By using LPD (Liquid Phase Deposition) method, SiO2 thin film can be formed in H2SiF6 aqueous solution below 50°C. However, in almost all cases, thin films formed by LPD method were on glass substrate. Therefore, in this study, problems concerning the SiO2 film formation process on SUS304 stainless steel substrate were examined by incorporating various electrochemical techniques. From the results of potential and current density measurements under coupling conditions with a Pt counter electrode, the importance of keeping SiO2 supersaturated state of solution and the need of pretreatment and cathodic protection of stainless steel substrate were recognized for preventing the corrosion damage of substrate from the severe environment of H2SiF6 aqueous solution.Then, the thin SiO2 film formation process was examined through microscopic observations by SEM and chemical analysis by EPMA. As a result, the progress in the deposition process was recognized with time. However, some defects were recognized in the deposited thin SiO2 film on SUS304 stainless steel substrate. These defects may strongly influence the corrosion resistance of SiO2 thin film coated steel. On the other hand, some acceleration in the thin film formation process was recognized when the deposition was conducted under a cathodically protecting condition at which an aluminum piece was used as a sacrificial anode. It may be brought about by the acceleration in anodic dissolution of aluminun piece and also by the pH increase with H2 gas generation in the electrochemical reaction.

ＴｉＮ被覆したステンレス鋼の硫酸水溶液での耐食性

TiN films were deposited under various conditions onto SUS304 stainless steel substrates by a hollow cathode discharge (HCD) type ion plating process. The corrosion resistance of the TiN-coated specimens in the active region was estimated in aqueous solutions of sulfuric acid, mainly by an electrochemical method. Measurements of the anodic polarization curves showed that the critical current density for passivation of the TiN-coated specimens was smaller than that for specimens without a TiN coating, that is, that active dissolution was retarded by TiN coating. The cathodic reaction tended to be similarly retarded by TiN coating. The corrosion resistance of the TiN-coated specimens was further improved by Ti undercoating and TiC coating under the TiN coating layer. This is attributed to the fact that the Ti undercoating and TiC coating decreased the number of defects that penetrate through the coating layers to the stainless steel substrate, that is, increased the intercepting effect of the coating layers from its surroundings. The intercepting effect of the coating layer from the surroundings of the specimens treated at 300°C was superior to that of the specimens treated at 450°C. The effect of hydrogen on the crack morphology of the TiN films was remarkable, and in the case of TiN films put into a hydrogen surroundings, cleavage fractures occurred.

ＨＣＤ法によるＴｉＮコーティング鋼の耐食性に及ぼす成膜条件の影響

TiN films were deposited under different bias voltages onto SUS304 stainless steel substrates by a hollow cathode discharge (HCD) type ion plating process. The corrosion resistance of the TiN-coated specimens in the active region was estimated in aqueous solutions of sulfuric acid, mainly by an electrochemical method. The adherence between the TiN film and stainless steel substrate was improved by applying a bias voltage, and the films deposited using a bias voltage exhibited a dense and distinct columnar structure. Measurements of the anodic polarization curves showed that the critical current density for passivation of the TiN-coated specimens was smaller than that for specimens without a TiN coating, that is, that active dissolution was retarded by TiN coating. The corrosion resistance of the TiN-coated specimens was further improved by applying a bias voltage, and this is attributed to the fact that the bias voltage decreased the amount of defects in the TiN films, that is, increased the intercepting effect of the film from it's surroundings. A compressive stress existed in the TiN films, the magnitude of which depended on the bias voltage. Moreover, there appeared to be good a correlation between the residual stress in the film and the corrosion resistance of the coated specimens.