scholarly journals Effects of nanostructured, diamondlike, carbon coating and nitrocarburizing on the frictional properties and biocompatibility of orthodontic stainless steel wires

2016 ◽  
Vol 86 (5) ◽  
pp. 782-788 ◽  
Author(s):  
Hao Zhang ◽  
Shuyu Guo ◽  
Dongyue Wang ◽  
Tingting Zhou ◽  
Lin Wang ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Corrosion Resistance ◽  
Elastic Modulus ◽  
Corrosion Current Density ◽  
Surface Hardness ◽  
Corrosion Current ◽  
Frictional Properties ◽  
Dlc Coating ◽  
Steel Wires ◽  
Diamondlike Carbon

ABSTRACT Objective:  To evaluate and compare the effects of nanostructured, diamondlike, carbon (DLC) coating and nitrocarburizing on the frictional properties and biocompatibility of orthodontic stainless steel archwires. Materials and Methods:  Plasma-enhanced chemical vapor deposition technology was applied to coat DLC films onto the surface of austenitic stainless steel wires, and salt-bath nitrocarburizing technology was employed to achieve surface hardening of other wires. Surface and cross-sectional characteristics, microhardness, modulus of elasticity, friction resistance, corrosion resistance, and cell toxicity of the modified and control wires were analyzed. Results:  The surfaces of the DLC-coated and nitrocarburized wires were both smooth and even. Compared with the control, the DLC-coated wires were increased in surface hardness 1.46 times, decreased in elastic modulus, reduced in kinetic friction coefficient by 40.71%, and decreased in corrosion current density by two orders of magnitude. The nitrocarburized wire was increased in surface hardness 2.39 times, exhibited an unchanged elastic modulus, demonstrated a decrease in maximum static friction force of 22.2%, and rose in corrosion current density two orders of magnitude. Cytotoxicity tests revealed no significant toxicity associated with the modified wires. Conclusions:  DLC coating and nitrocarburizing significantly improved the surface hardness of the wires, reduced friction, and exhibited good biocompatibility. The nanostructured DLC coating provided excellent corrosion resistance and good elasticity, and while the nitrocarburizing technique substantially improved frictional properties, it reduced the corrosion resistance of the stainless steel wires to a lesser extent.

scholarly journals CHARACTERISTICS OF AISI 420 STAINLESS STEEL MODIFIED BY COMBINING GAS NITRIDING AND CrN COATING

2021 ◽  
Vol 27 (3) ◽  
pp. 146-151
Author(s):  
Thanh Van Nguyen ◽  
Van Thanh Doan ◽  
Trung Van Trinh ◽  
Huy Van Vu
Keyword(s):  
Stainless Steel ◽  
Corrosion Resistance ◽  
Load Capacity ◽  
Steel Substrate ◽  
Surface Hardness ◽  
Corrosion Current ◽  
Crn Coating ◽  
Gas Nitriding ◽  
Duplex Coating ◽  
Aisi 420

AISI 420 stainless steel is widely used in applications where wear and corrosion resistance are required. However, the heat treatment and nitriding process can drastically reduce the corrosion resistance of this stainless steel. This article focuses on investigating the influence of steel substrate and gas nitriding efficiency at two temperatures of 520 oC and 550 oC on some properties of CrN coating. The experiments were carried out to evaluate the surface hardness, microstructure and phase composition of nitrided layers. The coating adhesion and load capacity of the coating were performed according to VDI 3198 standard. Electrochemical testing was performed in a solution of 3.5% NaCl and then using the Tafel method to determine the corrosion current and corrosion potential. The thickness of CrN and CrN/CrN coating was 1.6 μm and 3 μm, respectively. The study showed that the corrosion resistance of coatings fabricated through duplex technology was affected not only by the normal defects but also by the porosity on the nitrided surface. The corrosion resistance of multilayer duplex coating was improved compare with mono-layer duplex coating due to its ability to cover and reduce pores and pitting defects.

scholarly journals Corrosion Behavior of Diffusion Bonding Joints of (OFHC) Copper with Stainless Steel 304L in 3.5% NaCl

2018 ◽  
Vol 21 (1) ◽  
pp. 74
Author(s):  
Sami Abualnoun Ajeel ◽  
Ahmed Ali Akbar Akbar ◽  
Safaa Mohammed Hassoni
Keyword(s):  
Stainless Steel ◽  
Corrosion Resistance ◽  
Corrosion Behavior ◽  
Current Density ◽  
Diffusion Bonding ◽  
Corrosion Current Density ◽  
Pure Copper ◽  
Corrosion Current ◽  
Stainless Steel 304L ◽  
Materials Used

The present work deals with direct diffusion bonding welding without interlayer of austenitic stainless steel type AISI 304L with Oxygen Free High Conductivity pure copper (OFHC) in vacuum atmosphere (1.5 *10-5 mbr.). The optimum bonding conditions are temperature of 650 ◦C, duration time of 45 min. and the applied stress of 30 MPa, in order to secure a tight contact between the mating surfaces. The corrosion behavior of diffusion bonding joints in 3.5% Nacl is studied to evaluate the corrosion resistance of welding joints by using Potentiodynamic method. The observed microstructure of corroded specimen of optimum diffusion bonding joint shows that the corrosion current density has low value as compared with base materials used. During polarization, galvanic coupling is observed between two materials used. At passivity region, inverse polarity is occurred at 450mV. Therefore, passive stainless steel 304 L behaves as cathode respective to pure copper, the corrosion behavior of the diffusion bonding joint was mostly by copper side. The corrosion results indicate the presence of galvanic effect. The corrosion current density of copper, stainless steel 304L and bond joints condition were (3.66 µA/cm2, 1.62 µA/cm2 and 1.85µA/cm2) respectively. A SEM examination of corroded diffusion bonding joint indicates that the galvanic corrosion happened on copper side. The corrosion rate of bonding joint conditions was 0.85 mpy, which is less than 1%. This means that corrosion resistance of bond joint is more than excellent.

scholarly journals Corrosion Behavior and Osteogenic Activity of a Biodegradable Orthopedic Implant Mg–Si Alloy with a Gradient Structure

Metals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 781
Author(s):  
Weiyan Jiang ◽  
Wenzhou Yu
Keyword(s):  
Corrosion Resistance ◽  
Corrosion Behavior ◽  
Polarization Resistance ◽  
Corrosion Current Density ◽  
Corrosion Current ◽  
Gradient Structure ◽  
Orthopedic Implant ◽  
Biological Functions ◽  
Alloy Matrix ◽  
Osteogenic Activity

A gradient Mg-8 wt % Si alloy, which was composed of the agglomerated Mg2Si crystals coating (GMS8-1) and the eutectic Mg–Si alloy matrix (GMS8-2), was designed for biodegradable orthopedic implant materials. The bio-corrosion behavior was evaluated by the electrochemical measurements and the immersion tests. The results show that a significant improvement of bio-corrosion resistance was achieved by using the gradient Mg–Si alloy, as compared with the traditional Mg-8 wt % Si alloy (MS8), which should be attributed to the compact and insoluble Mg2Si phase distributed on the surface of the material. Especially, GMS8-1 exhibits the highest polarization resistance of 1610 Ω, the lowest corrosion current density of 1.7 × 10−6 A.cm−2, and the slowest corrosion rate of 0.10 mm/year. In addition, GMS8-1 and GMS8-2 show better osteogenic activity than MS8, with no cytotoxicity to MC3T3-E1 cells. This work provides a new way to design a gradient biodegradable Mg alloys with some certain biological functions.

scholarly journals Structure, Corrosion Resistance, Mechanical and Tribological Properties of ZrB2 and Zr-B-N Coatings

Metals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1194
Author(s):  
Philipp Kiryukhantsev-Korneev ◽  
Alina Sytchenko ◽  
Yuriy Kaplanskii ◽  
Alexander Sheveyko ◽  
Stepan Vorotilo ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Tribological Properties ◽  
Current Density ◽  
Corrosion Current Density ◽  
Elastic Recovery ◽  
Optical Emission ◽  
Corrosion Current ◽  
Impact Testing ◽  
Total Oxidation ◽  
Mechanical And Tribological Properties

The coatings ZrB2 and Zr-B-N were deposited by magnetron sputtering of ZrB2 target in Ar and Ar–15%N2 atmospheres. The structure and properties of the coatings were investigated via scanning and transmission electron microscopy, energy dispersion analysis, optical profilometry, glowing discharge optical emission spectroscopy and X-ray diffraction analysis. Mechanical and tribological properties of the coatings were investigated using nanoindentation, “pin-on-disc” tribological testing and “ball-on-plate” impact testing. Free corrosion potential and corrosion current density were measured by electrochemical testing in 1N H2SO4 and 3.5%NaCl solutions. The oxidation resistance of the coatings was investigated in the 600–800 °С temperature interval. The coatings deposited in Ar contained 4–11 nm grains of the h-ZrB2 phase along with free boron. Nitrogen-containing coatings consisted of finer crystals (1–4 nm) of h-ZrB2, separated by interlayers of amorphous a-BN. Both types of coatings featured hardness of 22–23 GPa; however, the introduction of nitrogen decreased the coating’s elastic modulus from 342 to 266 GPa and increased the elastic recovery from 62 to 72%, which enhanced the wear resistance of the coatings. N-doped coatings demonstrated a relatively low friction coefficient of 0.4 and a specific wear rate of ~1.3 × 10−6 mm3N−1m−1. Electrochemical investigations revealed that the introduction of nitrogen into the coatings resulted in the decrease of corrosion current density in 3.5% NaCl and 1N H2SO4 solution up to 3.5 and 5 times, correspondingly. The superior corrosion resistance of Zr-В-N coatings was related to the finer grains size and increased volume of the BN phase. The samples ZrB2 and Zr-B-N resisted oxidation at 600 °C. N-free coatings resisted oxidation (up to 800 °С) and the diffusion of metallic elements from the substrate better. In contrast, Zr-B-N coatings experienced total oxidation and formed loose oxide layers, which could be easily removed from the substrate.

scholarly journals Surface Modification of a Nickel-Free Austenitic Stainless Steel by Low-Temperature Nitriding

Metals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1845
Author(s):  
Francesca Borgioli ◽  
Emanuele Galvanetto ◽  
Tiberio Bacci
Keyword(s):  
Stainless Steel ◽  
Corrosion Resistance ◽  
Austenitic Stainless Steel ◽  
Low Temperature ◽  
Stainless Steels ◽  
Volume Fraction ◽  
Surface Hardness ◽  
Austenitic Stainless Steels ◽  
Surface Layers ◽  
Modified Surface

Low-temperature nitriding allows to improve surface hardening of austenitic stainless steels, maintaining or even increasing their corrosion resistance. The treatment conditions to be used in order to avoid the precipitation of large amounts of nitrides are strictly related to alloy composition. When nickel is substituted by manganese as an austenite forming element, the production of nitride-free modified surface layers becomes a challenge, since manganese is a nitride forming element while nickel is not. In this study, the effects of nitriding conditions on the characteristics of the modified surface layers obtained on an austenitic stainless steel having a high manganese content and a negligible nickel one, a so-called nickel-free austenitic stainless steel, were investigated. Microstructure, phase composition, surface microhardness, and corrosion behavior in 5% NaCl were evaluated. The obtained results suggest that the precipitation of a large volume fraction of nitrides can be avoided using treatment temperatures lower than those usually employed for nickel-containing austenitic stainless steels. Nitriding at 360 and 380 °C for duration up to 5 h allows to produce modified surface layers, consisting mainly of the so-called expanded austenite or gN, which increase surface hardness in comparison with the untreated steel. Using selected conditions, corrosion resistance can also be significantly improved.

Corrosion Resistance of Nickel-Free Austenitic Stainless Steels and their Nanocomposites with Hydroxyapatite in Ringer's Solution

2011 ◽  
Vol 674 ◽  
pp. 159-163 ◽  
Author(s):  
Maciej Tulinski ◽  
Mieczyslaw Jurczyk
Keyword(s):  
Stainless Steel ◽  
Corrosion Resistance ◽  
Mechanical Alloying ◽  
Stainless Steels ◽  
Austenitic Stainless Steels ◽  
Orthopedic Implants ◽  
Corrosion Current ◽  
Similar Process ◽  
Distinct Advantage ◽  
Ion Release

In this work Ni-free austenitic stainless steels with nanostructure and their nanocomposites were synthesized by mechanical alloying (MA), heat treatment and nitriding of elemental microcrystalline Fe, Cr, Mn and Mo powders with addition of hydroxyapatite (HA). Microhardness and corrosion tests' results of obtained materials are presented. Mechanical alloying and nitriding are very effective technologies to improve the corrosion resistance of stainless steel. Decreasing the corrosion current density is a distinct advantage for prevention of ion release and it leads to better cytocompatibility. Similar process in case of nanocomposites of stainless steel with hydroxyapatite helps achieve even better mechanical properties and corrosion resistance. Hence nanocrystalline nickel-free stainless steels and nickel-free stainless steel/hydroxyapatite nanocomposites could be promising bionanomaterials for use as a hard tissue replacement implants, e.g. orthopedic implants.

scholarly journals Applying Baghdadite/PCL/Chitosan Nanocomposite Coating on AZ91 Magnesium Alloy to Improve Corrosion Behavior, Bioactivity, and Biodegradability

Coatings ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 789 ◽  
Author(s):  
Farzad Soleymani ◽  
Rahmatollah Emadi ◽  
Sorour Sadeghzade ◽  
Fariborz Tavangarian
Keyword(s):  
Corrosion Resistance ◽  
Biomedical Applications ◽  
Corrosion Current Density ◽  
Ceramic Coating ◽  
Alloy Coating ◽  
Corrosion Current ◽  
Nanocomposite Coating ◽  
Az91 Alloy ◽  
Az91 Magnesium Alloy ◽  
Az91 Magnesium

Magnesium alloys have received a great amount of attention regarding being used in biomedical applications; however, they show high degradability, poor bioactivity, and biocompatibility. To improve these properties, surface modification and various types of coatings have been applied. In this study, an anodized AZ91 alloy was coated with a polymer matrix composite made of polycaprolactone/chitosan (PCL/Ch) with different percentages of baghdadite to improve its resistance to corrosion, bioactivity, and biocompatibility. The effects of different percentages of baghdadite (0 wt %, 1 wt %, 3 wt %, and 5 wt %) on the surface microstructure, corrosion resistance, roughness, and wettability were evaluated. The results indicated that the applied nano-polymer-ceramic coating including 3 wt % baghdadite was hydrophobic, which consequently increased the corrosion resistance and decreased the corrosion current density of the anodized AZ91 alloy. Coating with 3 wt % baghdadite increased the roughness of AZ91 from 0.329 ± 0.02 to 7.026 ± 0.31 μm. After applying the polymer-ceramic coating on the surface of anodized AZ91, the corrosion products changed into calcium–phosphate compounds instead of Mg(OH)2, which is more stable in a physiological environment.

The Effect of Surface Self-Nanocrystallization on Low-Temperature Gas Carburization for AISI 316L Steel

2019 ◽  
Vol 795 ◽  
pp. 137-144
Author(s):  
Zhe Liu ◽  
Ya Wei Peng ◽  
Jian Ming Gong ◽  
Chao Ming Chen
Keyword(s):  
Stainless Steel ◽  
Elastic Modulus ◽  
Austenitic Stainless Steel ◽  
Low Temperature ◽  
Surface Hardness ◽  
Electron Probe Micro Analyzer ◽  
Gas Carburizing ◽  
316L Steel ◽  
Negative Effect ◽  
Effect Of Surface

In this work, the effect of surface self-nanocrystallization on low-temperature gas carburizing for AISI316L austenitic stainless steel has been studied. The surface ultrasonic rolling processing (SURP) was used to prepare nanostructured surface layers, and then the un-SURP and SURP samples were treated by LTGC at 470 °C for 10 h, 20 h and 30 h. In order to analyze the effect of surface self-nanocrystallization on low-temperature gas carburizing, optical microscopy (OM), atomic force microscope (AFM), scanning electron probe micro-analyzer (EPMA) and nano-indentation analyzer were used. The results show depth of SURP-induced plastic deformation layer was about 330 μm. Meanwhile, the surface hardness and elastic modulus were increased but the surface roughness decreased obviously after SURP. After low-temperature gas carburizing, according to the results of the thickness, carbon concentration, nano-hardness and elastic modulus of the carburized layer, the conclusion is that surface self-nanocrystallization carried by SURP has a negative effect on the low-temperature gas carburizing for AISI316L austenitic stainless steel and with the increase of carburizing time, the greater the adverse effect on carburizing.

scholarly journals Preparation of Ti–Zr-Based Conversion Coating on 5052 Aluminum Alloy, and Its Corrosion Resistance and Antifouling Performance

Coatings ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 397 ◽  
Author(s):  
Hehong Zhang ◽  
Xiaofeng Zhang ◽  
Xuhui Zhao ◽  
Yuming Tang ◽  
Yu Zuo
Keyword(s):  
Corrosion Resistance ◽  
Surface Modification ◽  
Aluminum Alloy ◽  
Current Density ◽  
Corrosion Current Density ◽  
Salt Water ◽  
Water Immersion ◽  
Chemical Conversion ◽  
Corrosion Current ◽  
Conversion Coating

A chemical conversion coating on 5052 aluminum alloy was prepared by using K2ZrF6 and K2TiF6 as the main salts, KMnO4 as the oxidant and NaF as the accelerant. The surface morphology, structure and composition were analyzed by SEM, EDS, FT–IR and XPS. The corrosion resistance of the conversion coating was studied by salt water immersion and polarization curve analysis. The influence of fluorosilane (FAS-17) surface modification on its antifouling property was also discussed. The results showed that the prepared conversion coating mainly consisted of AlF3·3H2O, Al2O3, MnO2 and TiO2, and exhibited good corrosion resistance. Its corrosion potential in 3.5 wt % NaCl solution was positively shifted about 590 mV and the corrosion current density was dropped from 1.10 to 0.48 μA cm−2. By sealing treatment in NiF2 solution, its corrosion resistance was further improved yielding a corrosion current density drop of 0.04 μA cm−2. By fluorosilane (FAS-17) surface modification, the conversion coating became hydrophobic due to low-surface-energy groups such as CF2 and CF3, and the contact angle reached 136.8°. Moreover, by FAS-17 modification, the corrosion resistance was enhanced significantly and its corrosion rate decreased by about 25 times.

Effect of Gas Content and Treatment Temperature on the Characteristic of Surface Layers of Low Temperature Plasma Nitrided 316L Austenitic Stainless Steel

2018 ◽  
Vol 941 ◽  
pp. 1784-1789
Author(s):  
Insup Lee
Keyword(s):  
Stainless Steel ◽  
Corrosion Resistance ◽  
Surface Hardness ◽  
Treatment Temperature ◽  
S Phase ◽  
Gas Content ◽  
Low Temperature Plasma ◽  
Temperature Plasma ◽  
Phase Layer ◽  
316L Austenitic Stainless Steel

The effect of gas content and treatment temperature on the surface characteristics of hardened layers of low temperature plasma nitrided 316L Austenitic Stainless Steel was investigated. The process was performed at fixed processing time at 15Hr and changing the N2content from 10% to 25%, changing the treatment temperature from 370 °C to 430 °C. The surface hardness and the thickness of expanded austenite (S-Phase) layer increase with increasing both temperature and nitrogen content. At 430°C processing temperature and 25% N2content, the S-phase layer thickness increased up to 13 μm and surface hardness increased about 3.5 times of that of untreated sample which is 880 HV0.1(before treatment 250HV0.1hardness). However, the XRD pattern of the this sample shows the presence of γ'-(Fe,Cr)4N precipitation on the surface which is the reason for the increased corrosion current density that results in increased corrosion rate. Thus the corrosion resistance degrades and presents even worst behavior comparing that of before treatment. Therefore, for increasing the corrosion behavior, further research was conducted by fixing the N2content at 10% with changing the CH4content from 0% to 5%. The best results were found when treated at 430°C with 5% CH4content. At this condition the S-phase thickness increase to around 17μm and surface hardness (980 HV0.1) is improved about 3.9 times of the hardness of untreated one. This sample also showed superior corrosion resistance than the other treated samples and the untreated one due to much higher pitting potential.

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