Static Corrosion Tests Research Articles

Effect of III-Pass on Microstructure, Micro Hardness and Static Immersion Corrosion Resistance of AA6061-T6/SiCp Surface Composite Fabricated by Friction Stir Processing

In this current investigation, SiC particles 20μm in average size were incorporated into the commercially AA6061-T6 to prepare surface composite by using Friction stir processing (FSP). The morphology of the reinforcement inside the Al matrix has been evaluated from scanning electron microscope (SEM) and the corrosion characteristics of the resulted composite were evaluated using static immersion corrosion (SIC) behavior in 3.5% NaCl aqueous solution at various regimes. From the results, it observed that the SiC particles were distributed uniformly inside the stir zone (SZ) in both first and third-pass of FSP. The micro hardness of stir zone with SiC particles of I-pass was higher compared to III-pass and as-received Al alloy. In static immersion corrosion test the FSP AA6061-T6/SiCp exhibited significantly greater corrosion resistance in I-pass than compared to the III-pass and as-received Al alloy.

Influence of topographical features on the fluoride corrosion of Ni–Ti orthodontic archwires

Different manufacturing processes of Ni-Ti archwires respond differently to corrosion due to the surface conditions involved. In this study, several topographical features and their influence upon fluoride corrosion were studied. Four topographies (smooth, dimple, scratch, and crack) according to the main surface defect were characterized (n = 40). Static corrosion tests were performed in artificial saliva with fluorated prophylactic gel (12500 ppm) for 28 days. The surface was characterized by SEM and laser confocal microscopy. Standard electrochemical corrosion (open circuit potential, corrosion potential and corrosion current density) was performed. Statistical analysis was carried out using the ANOVA test (α ≤ 0.05). An increase was observed in the surface defects and/or roughness of the cracked and scratched surfaces. These defects produced an important increase in corrosion behavior. The best surfaces for the orthodontic archwires were the smooth and dimpled surfaces, respectively. The increase in defects was independent of roughness. Manufacturing processes that produce surface cracks should be avoided in orthodontic applications.

Effect of Sn on Corrosion Resistance of Mg-6Al-1.2Y-0.9Nd Alloy

The effect of Sn addition on corrosion behavior of Mg-6Al-1.2Y-0.9Nd alloy in 3.5wt.% NaCl solution has been researched by static corrosion tests, corrosion morphologies observation, microstructure and corrosion scale analysis. The result shows that, with the content of Sn increasing, the corrosion rate decreases at first and then increases. When the addition of Sn is 1wt.%, the corrosion rate is the lowest and the corrosion resistance is improved obviously.

The Anti-Erosion Properties of Pyrochlore Simulated Waste Forms

MCC-1 static short-term corrosion tests were performed to pyrochlore simulated waste forms in deionized water, at 90°C. Experimental results show that pyrochlore simulated waste forms has a good anti-leaching property. Both the normalized mass loss rate and the normalized mass loss of element Ce decrease with soaking time increasing in the short test. The corrosion process is co-dominated by the leaching agent and the corrosion temperature.

Tribo-Electrochemical Performance of Copper ECMP in Mixed Phosphate Electrolyte

A mixed phosphate slurry is screened out first in terms of inhibition efficiency of the inhibitor by electrochemical static-corrosion test of copper for different concentrations of H3PO4 and BTA. Then ECMP experiments are carried out on a modified pin-on-disk type tribo-electrochemical tester for the candidate slurry under the potential range of applied voltage, with the anodic current and friction coefficient recorded and MRR measured. It is found that copper ECMP can achieve good surface quality with a high MRR under 0.75 V anodic potential in slurry of 10%KH2PO4 + 5%H3PO4+0.03M BTA. Down force is found to have little effect on MRR in the mixed slurry, this pressure-independent characteristics may help reduce the pattern effect during patterned wafer polishing.

Corrosion Resistance of the Eletrodeposition Nano-TiO<sub>2</sub>/Ni Composite Coating on AZ91HP Mg Alloy

The eletrodeposition nano-TiO2/Ni composite coating on AZ91PH Mg alloy was prepared using the nano-TiO2 as the second phase particles. The corrosion resistance of the composite coating was measured by the static immerging corrosion test and the polarization curve test. The result shows that the corrosion resistance of the composite coating was better than that of Mg alloy. The corrosion resistance of the composite coating was optimal when the content of nano-TiO2 in the plating solution was 10g/l-15g/l.

Research on Corrosion Behavior of Fe-B Eutectic Alloy in Liquid Zinc

The static constant corrosion tests on Fe-B eutectic alloy are investigated in liquid zinc at 500°C. The systematic observation and research of the corrosion layer are performed using SEM, TEM, XRD. The results show that corrosion resistance of Fe-B eutectic alloy in liquid zinc is perfect. Corrosion products are Fe3B and FeZn7. The corrosion layer is regular, the structure of which is hollow dendritic skeleton and the thickness of which increases with the corrosion time extending. Corrosion process is that the interdiffusion of ferro and zinc atomic results in corrosion layer formation and the corrosion layer ruptures and dissolves under the action of thermal stress and impact stress of liquid zinc. The process repeating leads to the failure of the matrix eventually.

Behaviour of the antioxidant tert-butylhydroquinone on the storage stability and corrosive character of biodiesel

The behaviour of the antioxidant tert-butylhydroquinone (TBHQ) on the storage stability of biodiesel was investigated. Storage conditions were simulated through static immersion corrosion tests in biodiesel (with and without TBHQ) using copper coupons. Measurements of oxidation stability (Rancimat induction period) and metal release at different stages of corrosion were performed. After 24h of the static immersion test, the neat and TBHQ-doped biodiesels presented induction times below the EN 14214 limit (6h). Copper release was more intense in the neat biodiesel which evidenced that TBHQ retarded the corrosion process as a corrosion inhibitor. Ion trap–time-of-flight mass spectrometry (IT–TOF-MS) revealed the presence of considerable amounts of tert-butylquinone (TBQ) in the TBHQ-doped biodiesel exposed to the corrosion process. As TBHQ molecules adsorb at the copper surface to inhibit corrosion, these molecules are catalytically oxidised to TBQ. IT–TOF-MS also indicated the formation of new molecules of high molecular weight only presented in the TBHQ-doped biodiesel deteriorated by the corrosion process. MS2 spectra gave clear evidence of the formation of new complexes between free radicals of long-chain molecules (fatty acid derivatives) and TBQ radicals during biodiesel deterioration.

Effect of Y on Microstructure and Corrosion Resistance of AZ61 Magnesium Alloy

The effect of Y addition on the microstructure of AZ61 alloy was investigated by optical microscopy (OM), X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM). The corrosion behavior of AZ61 alloy with Y addition in 3.5 % NaCl solution was studied by static weight loss and polarization curves corrosion tests. The results show that AZ61 alloy with Y addition can refine grain size of the matrix and alter the distribution of the phase β-Mg17Al12 from continuous network morphology transition to small and dispersive distribution along the grain boundary by forming the second phase Al2Y which has a high melting point. In addition, the addition of Y can decrease the corrosion current density of AZ61 magnesium alloy in 3.5% NaCl solution, thereby improving the corrosion resistance of AZ61 magnesium alloy. Results show that AZ61 magnesium alloy with 1.0% Y has the most refined microstructure and the best corrosion resistance.

Laser remelting of alumina tile surfaces: corrosion testing in aqueous solution

Laser treatment of alumina surfaces in a nitrogen gas environment was carried out and the corrosion response of the resulting surfaces is examined. The corrosion tests were carried out using 5% NaCl solution for seven days, with continuous steering by a magnetic stirrer. Metallurgical and morphological changes in the laser irradiated region are examined using the scanning electron microscope, optical microscope, X-ray diffraction. It was found that formation of nitride (AlN) compounds was evident with a compact and dense structure formed in the laser irradiated region. Moreover, a few shallow pit sites are evident around the crack tips after the static corrosion tests, especially at a high laser output power.

Screening Test of Phosphoric Acid-BTA Slurries for Copper ECMP Based on Static Inhibition Efficiency

An ECMP slurry screening protocol is proposed based on inhibition efficiency of inhibitor in copper static corrosion test, aiming at enhancing the planarization efficiency of copper ECMP slurries. The elctrochemical properties of copper in electrolytes including H3PO4 and BTA with different concentrations are studied basing on Linear Sweep Voltammetry (LSV) and chronoamperometry under static corrosion states. According to analysis of the anodic current, material removal rate (MRR) and inhibition efficiency of BTA, an electrolyte formula of 30 wt% H3PO4+0.01M BTA is sort out and the anodic potential on copper should be set below 0.5 V.

Corrosion experiments and materials developed for the Japanese HLM systems

The static corrosion tests in lead–bismuth eutectic (LBE) were conducted from 450 °C to 600 °C to understand corrosion behavior and develop corrosion resistant materials for heavy liquid metal systems. While increase of Cr content in steels enhances corrosion resistance in LBE, the effect approaches a constant value above 12 wt% of Cr. Corrosion depth in LBE increases with increasing temperature and corrosion attack becomes severe above 550 °C even under the condition of high oxygen concentration. Nickel dissolution and Pb–Bi penetration occur in 316SS and JPCA above 550 °C under the condition of high oxygen concentration. When oxygen concentration decreases below the level of Fe oxide formation, corrosion attack on these steels also becomes violent due to dissolution of various elements and grain boundary corrosion. Whereas additions of 1.5 wt% Si to T91 and 2.5 wt% Si to 316SS improve corrosion resistance, the effect is insufficient taking fluctuation of oxygen concentration in LBE into consideration. Furthermore, addition of 1.5 wt% Si to T91 causes rise in DBTT. A new coating method using Al, Ti and Fe powders produces corrosion resistant coating layers on 316SS. The coating layers containing 6–8 wt% Al exhibit good corrosion resistance at 550 °C for 3000 h in LBE containing 10 −6–10 −4 wt% of oxygen.

The Influence of Deformation on Dechromization Corrosion of CuCr Alloy in H<sub>3</sub>PO<sub>4</sub> Solutions

The influence of deformation on dechromization of CuCr alloy in H3PO4 solutions was investigated by static immersion corrosion tests. The properties of undeformed and deformed alloys were characterised by XRD, Metallograph, SEM and X-ray fluorescence spectrometer respectively. It is observed that the deformation plays an important role in dechromization of CuCr alloys in H3PO4 solutions. Compared with undeformed one, the deformed CuCr alloy’s incubation time of corrosion is shortened, the concentration and temperature of H3PO4 solutions needed for dechromization decrease. Consequently the tendency of dechromization increases. Surface analysis showed that the microstructure of the dechromization layer is scarcely influenced. Finally, the dechromisation mechanism was discussed.

Corrosion Behaviors of Borosilicate Glasses in Various Leaching Agents

Static short-term corrosion tests were performed to two kinds of borosilicate glasses in deionized water, at 70°C and 150°C, respectively. Same corrosion experiments were also carried out in other leaching agents, such as simulated under ground water of Beishan, sulfuric acid solution (pH=0.5) and potassium hydroxide solution (pH = 13). Experimental results show that both leaching agent and corrosion temperature co-dominate the corrosion process, and the temperature plays more important role. At low temperature of 70°C, the corrosion reaction is controlled by the ion diffusing in DIW at earlier stage. While in PHS, network hydrolysis reaction is the main corrosion mechanism.

Effect of rare-earth element Sm on the corrosion behavior of Mg-6Al-1.2Y-0.9Nd alloy

The effect of Sm (0 wt.%-2 wt.%) addition on the corrosion behavior of Mg-6Al-1.2Y-0.9Nd alloy in 3.5 wt.% NaCl solution has been studied by static corrosion tests, corrosion morphology observation, corrosion scale and microstructure analysis. The results show that, with the increasing of Sm content, the corrosion rate of the alloy decreases at first, then increases and reaches the valley at 0.5 wt.% Sm. The reason is that the proper content of Sm addition can refine the precipitates and make the component and microstructure uniform, and therefore, it remarkably improves the corrosion resistance of the alloy.

Continuum damage model for bioresorbable magnesium alloy devices — Application to coronary stents

The main drawback of a conventional stenting procedure is the high risk of restenosis. The idea of a stent that “disappears” after having fulfilled its mission is very intriguing and fascinating, since it can be expected that the stent mass decreases in time to allow the gradual transmission of the mechanical load to the surrounding tissues owing to controlled dissolution by corrosion. Magnesium and its alloys are appealing materials for designing biodegradable stents. The objective of this work is to develop, in a finite element framework, a model of magnesium degradation that is able to predict the corrosion rate, thus providing a valuable tool for the design of bioresorbable stents. Continuum damage mechanics is suitable for modeling several damage mechanisms, including different types of corrosion. In this study, the damage is assumed to be the superposition of stress corrosion and uniform microgalvanic corrosion processes. The former describes the stress-mediated localization of the corrosion attack through a stress-dependent evolution law, while the latter affects the free surface of the material exposed to an aggressive environment. Comparisons with experimental tests show that the developed model can reproduce the behavior of different magnesium alloys subjected to static corrosion tests. The study shows that parameter identification for a correct calibration of the model response on the results of uniform and stress corrosion experimental tests is reachable. Moreover, three-dimensional stenting procedures accounting for interaction with the arterial vessel are simulated, and it is shown how the proposed modeling approach gives the possibility of accounting for the combined effects of an aggressive environment and mechanical loading.

Ion Exchange Equilibrium Carbonate Treatment for Anticorrosion in Open Recirculating Cooling Water System

The study presents the results of ion exchange equilibrium carbonate treatment to prevent brass corrosion in open recirculating cooling water system. The treatment process can remove the hardness and aggressive anions, transform all of the ions into sodium bicarbonate and sodium carbonate, and form the open carbonate equilibrium system. In the static corrosion test, brass has the lowest corrosion rate of 1.36 × 10−3 mm/year in the open carbonate equilibrium system with total alkalinity of 6.00 × 10−3 mol/L. And during the 8-day dynamic simulation experiment of ion exchange equilibrium carbonate treatment, the recirculating water with total alkalinity of 6.00 × 10−3 mol/L that achieves open carbonate equilibrium state has the excellent buffer action when pH value of makeup water ranges from 5.94 to 11.26, and prevent brass after passivation with hydrogen peroxide (H2O2) solution from corrosion. So ion exchange equilibrium carbonate treatment is an effective and environmentally friendly method to treat the recirculating cooling water without corrosion inhibitor addition.

Hydrogen entry into Fe and high strength steels under simulated atmospheric corrosion

Electrochemical hydrogen permeation tests of Fe sheets under two cyclic corrosion test (CCT) conditions were performed to understand hydrogen entry behavior under atmospheric corrosions. Hydrogen entry into 1300 MPa-class high strength steels under two CCT conditions was also investigated using thermal desorption analysis. One CCT consisted of salt spray, dry and wet stages (Salt Spray CCT; SSCCT), and the other consisted of dry and wet stages after NaCl deposition (Dry–Wet CCT; DWCCT). The corrosion rates of Fe and the steels were almost constant under SSCCT and they decreased under DWCCT with time. Nevertheless, both CCTs resulted in increases in hydrogen permeation current and diffusible hydrogen content with time indicating enhancement of hydrogen entry. Corrosion current monitored by means of an atmospheric corrosion monitoring sensor consisting of Fe anode and Ag cathode decreased obviously under dry stage of the CCTs, whereas hydrogen permeation was high at the beginning of the dry stage. The discrepancy between hydrogen entry and corrosion rate indicates that the hydrogen entry is not directly controlled by corrosion rate. Increase in acidity of underlying rust layer with growth of rust layer monitored using a W/WO 3 electrode is considered to be one of the factors affecting the hydrogen entry efficiency.

Farklı ısıl işlem koşullarındaki 2024 aluminyum alaşımlarının korozyon sonrası mekanik özelliklerindeki kaybın belirlenmesi

In this study, the solution treatment of all 2024 Al-alloys was conducted at 510°C for 2,5 hour. Then, the solution heat-treated 2024 Al-alloys were subjected to the various heat treatments which are W, T4, T6 (100 o C-10h), T6 (190 o C-10h) and O temper conditions. The microstructure of the alloys were examined by opti- cal and scanning electron microscopy (SEM). Static immersion corrosion tests for the tensile samples were carried out in a 3.5 wt. % NaCl solution for 2 months, open to air, at room temperature. The tensile tests of the specimens were carried out before and after corrosion. The results obtained were compared and the losses occur- ring in the strength and elongation after corrosion were determined. The minimum loss was observed in T4 heat treatment while the maximum loss was occurred in W heat treatment.

Post-CMP Cleaning of Atom-Scale Planarization Surface of Computer Hard Disk Substrate

At present, the surface of computer hard disk substrate has reached atom-scale planarization after chemical mechanical polishing (CMP). Post-CMP cleaning is one of the key factors influencing the CMP performances. During cleaning, cleaning solution and cleaning methods play a key role in cleaning quality and effectiveness. In the present paper, alkylpolyoxyethylene alcohol carboxylic ester (FAC) surfactant was synthesized and its cleaning performances on atom-scale planarization surface of computer hard disk substrate were investigated. Microscope analysis indicated that the prepared detergent containing FAC surfactant exhibited improved cleaning performances compared with the commercial detergent. Further, inductively coupled plasma (ICP) atomic emission spectrometer, auger electron spectrogram (AES) and atomic force microscopy (AFM) analyses after static corrosion test showed that the prepared cleaning solution had lower corrosion to hard disk substrate.