The Influence of Heat Treatment and Plastic Deformation on the Bio-Degradation of a Mg–Y–RE Alloy

2009 ◽  
Vol 618-619 ◽  
pp. 71-74 ◽  
Author(s):  
Petra Gunde ◽  
Angela Furrer ◽  
Anja C. Hänzi ◽  
Patrik Schmutz ◽  
Peter J. Uggowitzer
Keyword(s):  
Heat Treatment ◽  
Corrosion Resistance ◽  
Oxide Layer ◽  
Human Body ◽  
Electrochemical Impedance ◽  
Essential Element ◽  
Heat Treatments ◽  
Protective Oxide ◽  
Degradation Behaviour ◽  
Polarisation Resistance

Magnesium has become an interesting candidate in the field of bioabsorbable implant materials; it is an essential element in the human body, biocompatible and degradable due to its low corrosion resistance in a pH range below 11.5. However, in the human body (pH  7.4) a magnesium implant might degrade too quickly and lose its mechanical strength before the tissue has fully healed. However, the corrosion resistance can be improved for example by the choice of a suitable Mg alloy containing corrosion-inhibiting elements such as yttrium or by the deployment of surface heat treatments at high temperatures causing protective oxide layers to form. We studied the bio-degradation behaviour of a Mg–Y–RE alloy in different heat treatment states by electrochemical impedance spectroscopy and immersion testing in simulated body fluid. The heat treatments caused a change in microstructure and also the formation of a thermal oxide layer on the sample surface, which consisted mainly of Y2O3 and which slowed the degradation and increased the polarisation resistance significantly compared to the polished state. However, in some specimens localised corrosion attacks occurred which drastically weakened the protective effect of the oxide. Because the implant might be deformed during implantation resulting in the oxide cracking, we intentionally strained the samples and investigated the degradation performance. These cracks led to a decrease in polarisation resistance compared to the non-strained oxidised state, but in comparison to the polished state they still perform better. Macroscopically, the degradation process occurred in a homogeneous way without localised corrosion attacks. Microscopically, corrosion attacks started at the cracks and undermined the oxide layer with time.

Material Property of a Passive Oxide Formed on Alloy 600

2007 ◽  
Vol 26-28 ◽  
pp. 937-940 ◽  
Author(s):  
Dong Jin Kim ◽  
Hyuk Chul Kwon ◽  
Seong Sik Hwang ◽  
Hong Pyo Kim
Keyword(s):  
Corrosion Resistance ◽  
Oxide Layer ◽  
Passive Film ◽  
Electrochemical Impedance ◽  
Oxide Films ◽  
Oxide Thickness ◽  
Solution Temperature ◽  
Alloy 600 ◽  
Pressurized Water ◽  
Electrochemical Behaviors

Alloy 600 is used as a material for a steam generator tubing in pressurized water reactors(PWR) due to its high corrosion resistance under a PWR environment. In spite of its corrosion resistance, a stress corrosion cracking(SCC) has occurred on the primary side as well as the secondary side of a tubing. It is known that a SCC is related to the electrochemical behaviors of an anodic dissolution and a passivation of a bare surface of metals and alloys. Therefore in the present work, the passive oxide films on Alloy 600 have been investigated as a function of the solution temperature by using a potentiodynamic polarization, electrochemical impedance spectroscopy and a TEM, equipped with EDS. Moreover the semiconductive property was evaluated by using the Mott-Schottky relation. It was found that the passivity depends on the chemical composition and the densification of the oxide film rather than the oxide thickness. As the solution temperature of 0.5M H3BO3 increased, the thickness of the passive film increased but the oxide resistance of the passive film was decreased, indicating that the measured current in the passive region of the potentiodynamic curve is closely related to the stability of the passive film rather than the oxide thickness. It was found that the oxide films were composed of an outer oxide layer with a lower resistance and an inner oxide layer with a relatively higher resistance. From the Mott-Schottky relation, the oxide formed at 300oC showed a p-type semiconductor property unlike the n-type oxide films up to 250oC.

Study of Corrosion Behavior of Conventional and Nanostructured WC-Co HVOF Sprayed Coats

2010 ◽  
Vol 64 ◽  
pp. 13-18 ◽  
Author(s):  
Shahin Khameneh Asl ◽  
Mohammad Reza Saghi Beyragh ◽  
Mahdi Ghassemi Kakroudi
Keyword(s):  
Electron Microscopy ◽  
Heat Treatment ◽  
Corrosion Resistance ◽  
Electrochemical Impedance ◽  
Heat Treating ◽  
Crystalline Phases ◽  
Chemical Test ◽  
Transmission Electron ◽  
Hvof Spray ◽  
Wear And Corrosion Resistance

Interest in nanomaterials has increased in recent years. This is due to the potential of size reduction to nanometric scale to provide properties of materials such as hardness, toughness, wear, and corrosion resistance. The current study is focused on WC-Co cermet coats, materials that are extensively used in applications requiring wear resistance. In this work, WC-17Co powder was thermally sprayed onto mild steel using High Velocity Oxy Fuel (HVOF) spray technique. The nanostructured specimen was produced from sprayed sample by heat-treating at 1100°C in a vacuum chamber. Their structures were studied by using X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Polarization and electrochemical impedance spectroscopy (EIS) tests were performed on the both types of coated samples in 3.5% NaCl solution. The amorphous phase in WC-17Co coating was transformed to crystalline phases by heat treatment at high temperatures. The heat treatment of these coatings at high temperature also resulted in partially dissolution of WC particles and formation of new crystalline phases. Generation of these phases produced the nanostructured coating with better mechanical properties. Comparative electro chemical test results showed that, the heat treatment could improve corrosion resistance of the nanostructured WC-17Co coat than the as sprayed coats.

scholarly journals Electrochemical Anodizing Treatment to Enhance Localized Corrosion Resistance of Pure Titanium

2017 ◽  
Vol 15 (1) ◽  
pp. 19-24 ◽  
Author(s):  
Davide Prando ◽  
Andrea Brenna ◽  
Fabio M. Bolzoni ◽  
Maria V. Diamanti ◽  
Mariapia Pedeferri ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Titanium Alloys ◽  
Oxide Layer ◽  
Corrosion Behavior ◽  
Pure Titanium ◽  
Localized Corrosion ◽  
Anodic Current Density ◽  
Anodic Current ◽  
Protective Oxide ◽  
Pitting Potential

Background Titanium has outstanding corrosion resistance due to the thin protective oxide layer that is formed on its surface. Nevertheless, in harsh and severe environments, pure titanium may suffer localized corrosion. In those conditions, costly titanium alloys containing palladium, nickel and molybdenum are used. This purpose investigated how it is possible to control corrosion, at lower cost, by electrochemical surface treatment on pure titanium, increasing the thickness of the natural oxide layer. Methods Anodic oxidation was performed on titanium by immersion in H2SO4 solution and applying voltages ranging from 10 to 80 V. Different anodic current densities were considered. Potentiodynamic tests in chloride- and fluoride-containing solutions were carried out on anodized titanium to determine the pitting potential. Results All tested anodizing treatments increased corrosion resistance of pure titanium, but never reached the performance of titanium alloys. The best corrosion behavior was obtained on titanium anodized at voltages lower than 40 V at 20 mA/cm2. Conclusions Titanium samples anodized at low cell voltage were seen to give high corrosion resistance in chloride- and fluoride-containing solutions. Electrolyte bath and anodic current density have little effect on the corrosion behavior.

scholarly journals Effects of Processing Parameters on the Corrosion Performance of Plasma Electrolytic Oxidation Grown Oxide on Commercially Pure Aluminum

Metals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 394 ◽  
Author(s):  
Getinet Asrat Mengesha ◽  
Jinn P. Chu ◽  
Bih-Show Lou ◽  
Jyh-Wei Lee
Keyword(s):  
Surface Roughness ◽  
Corrosion Resistance ◽  
Oxide Layer ◽  
Layer Thickness ◽  
Surface Engineering ◽  
Electrochemical Impedance ◽  
Pure Aluminum ◽  
Corrosion Performance ◽  
Commercially Pure ◽  
Peo Coatings

The plasma electrolyte oxidation (PEO) process has been considered an environmentally friendly surface engineering method for improving the corrosion resistance of light weight metals. In this work, the corrosion resistance of commercially pure Al and PEO treated Al substrates were studied. The PEO layers were grown on commercially pure aluminum substrates using two different alkaline electrolytes with different addition concentrations of Si3N4 nanoparticles (0, 0.5 and 1.5 gL−1) and different duty cycles (25%, 50%, and 80%) at a fixed frequency. The corrosion properties of PEO coatings were investigated by the potentiodynamic polarization and electrochemical impedance spectroscopy test in 3.5 wt.% NaCl solutions. It showed that the weight gains, layer thickness and surface roughness of the PEO grown oxide layer increased with increasing concentrations of Si3N4 nanoparticles. The layer thickness, surface roughness, pore size, and porosity of the PEO oxide layer decreased with decreasing duty cycle. The layer thickness and weight gain of PEO coating followed a linear relationship. The PEO layer grown using the Na2B4O7∙10H2O contained electrolyte showed an excellent corrosion resistance and low surface roughness than other PEO coatings with Si3N4 nanoparticle additives. It is noticed that the corrosion performance of PEO coatings were not improved by the addition of Si3N4 nanoparticle in the electrolytic solutions, possibly due to its detrimental effect to the formation of a dense microstructure.

scholarly journals Evaluation of Heat-Treated AISI 316 Stainless Steel in Solar Furnaces to Be Used as Possible Implant Material

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 581
Author(s):  
Ioan Milosan ◽  
Monica Florescu ◽  
Daniel Cristea ◽  
Ionelia Voiculescu ◽  
Mihai Alin Pop ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Stainless Steel ◽  
Corrosion Resistance ◽  
Solar Energy ◽  
Heat Treatments ◽  
Solar Furnace ◽  
316 Stainless Steel ◽  
Heat Treated ◽  
Aisi 316 Stainless Steel ◽  
Aisi 316

The appropriate selection of implant materials is very important for the long-term success of the implants. A modified composition of AISI 316 stainless steel was treated using solar energy in a vertical axis solar furnace and it was subjected to a hyper-hardening treatment at a 1050 °C austenitizing temperature with a rapid cooling in cold water followed by three variants of tempering (150, 250, and 350 °C). After the heat treatment, the samples were analyzed in terms of hardness, microstructure (performed by scanning electron microscopy), and corrosion resistance. The electrochemical measurements were performed by potentiodynamic and electrochemical impedance spectroscopy in liquids that simulate biological fluids (NaCl 0.9% and Ringer’s solution). Different corrosion behaviors according to the heat treatment type have been observed and a passivation layer has formed on some of the heat-treated samples. The samples, heat-treated by immersion quenching, exhibit a significantly improved pitting corrosion resistance. The subsequent heat treatments, like tempering at 350 °C after quenching, also promote low corrosion rates. The heat treatments performed using solar energy applied on stainless steel can lead to good corrosion behavior and can be recommended as unconventional thermal processing of biocompatible materials.

Wear and Corrosion Resistance of Electroless Nickel-Boron Coated Mild Steel

2010 ◽  
Vol 638-642 ◽  
pp. 846-851 ◽  
Author(s):  
Abdoul Fatah Kanta ◽  
Véronique Vitry ◽  
Fabienne Delaunois
Keyword(s):  
Heat Treatment ◽  
Corrosion Resistance ◽  
Mild Steel ◽  
Electrochemical Impedance ◽  
Electroless Nickel ◽  
Uncoated Steel ◽  
Wear And Corrosion ◽  
Heat Treated ◽  
Wear And Corrosion Resistance ◽  
Hardening Heat Treatment

Nickel-boron coatings were synthesized on mild steel by the electroless deposition method. Some of the coatings were submitted to a hardening heat treatment at 400°C during 1 hour in an atmosphere containing 95% Ar and 5% H2. Uncoated steel, treated and untreated samples were submitted to the Taber abrasion test to assess their wear resistance. The wear track was then examined by SEM and roughness measurement. The Taber Wear Index of untreated samples was slightly better than that of steel but heat treated samples attained TWI as small as 13. The corrosion resistance of the samples was investigated by the way of polarization and electrochemical impedance spectroscopy (EIS) and the influence of the heat treatment was observed.

Effect of Heat Treatments on Stress Corrosion Behavior of 7050 Al Alloys in 3.5% NaCl Solution

2016 ◽  
Vol 877 ◽  
pp. 543-549
Author(s):  
Wei Wei Ren ◽  
Xing Feng Zhan ◽  
Lin Chi Zou ◽  
Qiang Li ◽  
Jun Feng Chen
Keyword(s):  
Corrosion Resistance ◽  
Strain Rate ◽  
Stress Corrosion ◽  
Corrosion Behavior ◽  
Electrochemical Impedance ◽  
Heat Treatments ◽  
Al Alloys ◽  
Slow Strain Rate ◽  
Nacl Solution ◽  
Stress Corrosion Resistance

Effect of heat treatments on the stress corrosion behavior of 7050 Al alloys in 3.5% NaCl solution has been investigated using slow strain rate tensile (SSRT) test. During the slow strain rate tensile process, electrochemical impedance spectroscopy (EIS) in real time was carried out to characterize the electrochemical behavior for different tempers 7050 Al alloys. The investigation shows that both the stress corrosion resistance of 7050 Al alloys is controlled by heat treatments due to the different precipitates state. The improvement of stress corrosion resistance is contributed to the tiny precipitates in matrix which are beneficial to corrosion potential and maintain passivation, and precipitates discontinuous distribution at grain boundary which obstruct intergranular crack connection. Moreover, base on the results, we find out retrogression and re-aging (RRA, i.e., T6 + 200 °C/ retrogression + water quench + T6) increases both tensile strength and stress corrosion resistance. The optimized of retrogression time is 30 minutes.

Study on the Corrosion Resistance Behavior of Multi-Elements Alloy CoCrFeNiTi0.5

2014 ◽  
Vol 541-542 ◽  
pp. 61-68
Author(s):  
Sheng Jiao Pang ◽  
Ping Li ◽  
Ting Ju Li ◽  
Jie Zhao
Keyword(s):  
Corrosion Resistance ◽  
Oxide Scale ◽  
Oxide Layer ◽  
Good Adhesion ◽  
Tube Material ◽  
Protective Oxide ◽  
Good Thermal Stability ◽  
The Matrix ◽  
Internal Sulfidation ◽  
Melting Point Eutectic

Multi-elements alloy with good thermal stability is expected to serve as the superheater tube material of ultra-supercritical boiler and may suffer from hot corrosion under the coal-fired atmosphere. In this study, the corrosion resistance behavior of multi-elements alloy CoCrFeNiTi0.5 coated with alkali metal sulfates at 750°C is investigated systematically. The results showed the corrosion kinetics curves of the alloy followed a parabolic growth rate. The corrosion products, which consisted of volatile Na (CrO4) (SO4), (Fe,Ni) xSy, Cr/Ti oxide as well as compound oxides with spinel structure AB2O4, were found in the oxide scale and internal attack zone of the alloy. The oxide layer had good adhesion with the matrix at the beginning of corrosion. Prolonging corrosion time, the oxide layer in thickness increased and became loose as well as porous. The micro-pores generated in the interface between the oxide scale and matrix with the occurrence of the internal oxidation and internal sulfidation. In a word, the corrosion resistance behavior of multi-elements alloy CoCrFeNiTi0.5 at 750°C can be attributed to the formation of the protective oxide layers and to the basic fluxing in molten Na4SO4 induced by low melting point eutectic.

Anodizing of A356 T6 Alloys Obtained by Sub-Liquidus Casting

2008 ◽  
Vol 141-143 ◽  
pp. 755-760 ◽  
Author(s):  
Antonio Forn ◽  
Isabel Espinosa ◽  
Maite T. Baile ◽  
Elisa Rupérez
Keyword(s):  
Heat Treatment ◽  
Corrosion Resistance ◽  
Oxide Layer ◽  
Silicon Crystals ◽  
Wear And Corrosion ◽  
Coating Formation ◽  
Trapped Gas ◽  
Semi Solid ◽  
Wear And Corrosion Resistance ◽  
Coating Growth

Semi solid processing reduces porosity and amount of trapped gas and it allows heat treatment T6 that improves a hard anodized oxide layer. The aim of this work is to show the anodizing possibility of A356 T6 components conformed by Sub-liquidus Casting (SLC) to improve wear and corrosion resistance. This work compares the anodizing effect on tribological properties and corrosion resistance between components obtained by A6061 T6 extruded alloys and from A356 T6 produced by SLC. The effect of rounded silicon crystals on the coating formation and the fracture produced during the coating growth are described.

scholarly journals Surface Modification of Ti-6Al-4V Alloy By Anodization Technique at Low Potential to Produce Oxide Layer

2020 ◽  
Vol 2 (3) ◽  
pp. 93-102
Author(s):  
Franciska Pramuji Lestari ◽  
Yeni Rian Sari ◽  
Fendy Rokhmanto ◽  
Talitha Asmaria ◽  
Andika Widya Pramono
Keyword(s):  
Corrosion Resistance ◽  
Oxide Layer ◽  
Electrochemical Impedance ◽  
Layer Growth ◽  
Electrochemical Anodization ◽  
Growth Surface ◽  
Tio2 Layer ◽  
Anodization Voltage ◽  
Definite Effect ◽  
Surface Alteration

        Due to their excellent biocompatibility, titanium alloys are tremendously as implants used, since relatively low modulus, corrosion resistance, and good fatigue strength. The biocompatibility, comes from the formation of natural Titanium dioxide (TiO2) layer. Therefore, TiO2 layer growth surface alteration is frequently applied to improve biological, chemical , and mechanical properties. TiO2 nanostructures are obtained under self-organization conditions by electrochemical anodization of Ti-6Al-4V. Parameters of anodization such as anodization time, voltage and addition of thiourea were evaluated in the composition of the H3PO4+NH4F solution. The morphology and elements of the Ti alloys surface were analyzed by Scanning Electron Microscopy (SEM) and Energy-Dispersive Spectroscopy (EDS), whereas potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) were used to evaluate the TiO2 layer in corrosion resistance. The results showed that the anodized Ti-6Al-4V alloy E-corr imcreased as the anodization voltage increased. Titanium alloy anodized using 12 V during 2 hours with H3PO4 + NH4F without thiourea solution  had the thickest of oxide layer and highest corrosion resistance. Higher applied voltages have been shown to increase the deposition rate and coating thickness. Addition of thiourea has a definite effect on the inhibition of oxide layer of titanium. In order to produce the optimum titanium surface, the required applied anodization voltage and addition of volume thiourea is necessary.  

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