Effect of pH of coating solution on the adhesion strength and corrosion resistance of hydroxyapatite and octacalcium phosphate coated WE43 alloy

2021 ◽  
pp. 088532822110125
Author(s):  
Tuyet Thi Anh Ngo ◽  
Sachiko Hiromoto ◽  
Linh Chi Do ◽  
Hanh Hong Pham ◽  
Le Hanh
Keyword(s):  
Corrosion Resistance ◽  
Adhesion Strength ◽  
Corrosion Current ◽  
Xrd Analysis ◽  
Octacalcium Phosphate ◽  
Solution Deposition ◽  
Chemical Solution Deposition Method ◽  
Before And After ◽  
Coating Layers ◽  
We43 Alloy

Hydroxyapatite (HAp) and octacalcium phosphate (OCP) layers were formed on Mg- 4mass% Y- 3mass% rare earth (WE43) alloy by a chemical solution deposition method at various pH values of pH 5.5, 6.2, 7.5, and 8.6. Adhesion strength of HAp and OCP layers was evaluated before and after immersing in a medium for 14 days by a pull-off test. The corrosion resistance of these coatings was measured by polarization tests performed in a simulated body fluid (SBF). XRD analysis demonstrated that HAp coating layers were formed at pH 7.5 and 8.6, while OCP coating layers were formed at pH 5.5 and 6.2. Adhesion test results showed that the as-coated pH7.5-HAp layer had the highest adhesion strength of 8.6 MPa, which was attributed to the very dense structure of the coating layer. The as-coated pH8.6-HAp layer showed the adhesion strength of 6.5 MPa. The adhesion strength of the as-coated pH5.5- and pH6.2-OCP layers was 3.9 and 7.1 MPa, respectively, that was governed by the thick and fragile property of the layers. After immersing in the medium for 14 days, the adhesion strength of pH7.5- and pH8.6-specimens decreased to 5.8 and 5.6 MPa, respectively. The pitting corrosion and formation of Mg(OH)2 under the HAp layers were responsible for the decrease of adhesion strength. The polarization tests in SBF at 37 °C showed that the corrosion current density decreased with the HAp and OCP coatings, indicating the improvement of the corrosion resistance of WE43 alloy. The HAp coatings improved the corrosion resistance more efficiently than the OCP coatings.

Effect of pH of Coating Solution on Adhesion Strength of Hydroxyapatite and Octacalcium Phosphate Coatings on AZ31 Magnesium Alloy

2020 ◽  
Vol 985 ◽  
pp. 156-164 ◽  
Author(s):  
Thi Anh Ngo Tuyet ◽  
Sachiko Hiromoto ◽  
Phong Ngoc Nguyen ◽  
Thi Pham San
Keyword(s):  
Adhesion Strength ◽  
Intermediate Layer ◽  
Ph Value ◽  
Layer Structure ◽  
Octacalcium Phosphate ◽  
Az31 Alloy ◽  
Solution Ph ◽  
Coating Solution ◽  
Chemical Solution Deposition Method ◽  
Before And After

Hydroxyapatite (HAp) and octacalcium phosphate (OCP) coatings were formed on a Mg-3Al-Zn (AZ31) alloy with a chemical solution deposition method using a Ca-EDTA solution at various pH levels. The adhesion strength of the coatings was examined using the pull-off method. The microstructures of HAp and OCP coatings were measured X-ray diffraction (XRD). The morphology and composition of the surface and cross section of the samples before and after the adhesion test were characterized using scanning electron microscopy (SEM), energy-dispersive spectrometry (EDS), and a 3D profilometer. The results showed that plate-like OCP crystals grew from a continuous OCP layer on the surface of the AZ31 substrate in the case of a pH 6.3 coating solution. At pH values of 7.5 and 8.6, the HAp coating showed a two-layer structure with a HAp rod-like outer layer and a HAp continuous inner layer. Regardless of the pH of the coating solutions, a very thin Mg (OH)2 intermediate layer was formed between OCP or HAp coating and substrate. The highest adhesion strength of the coatings was 6.7±0.5 MPa, achieved at a coating solution pH value of 7.5. A part of Mg (OH)2 layer remained on the substrate, indicating that the delamination occurred in the Mg (OH)2 intermediate layer. The primary particles in the inner layer formed at pH 7.5 was smaller than those at pH 8.6. This result indicates that the initial corrosion of substrate AZ31 at pH 7.5 was more rapidly than that at pH 8.6, presumably leading to the formation of mixed layer of Mg (OH)2 and calcium phosphate. Further investigation is necessary to understand the better adhesion strength at pH 7.5 than that at pH 8.6. This good adhesion could be due to the flawless and rod-like uniform crystal, which had the densest and finest structure on the surface.

Effect of Shot Peening on Microstructure and Properties of 34CrMo4 Alloy

2018 ◽  
Vol 934 ◽  
pp. 105-110 ◽  
Author(s):  
Ke Jian Li ◽  
Qiang Zheng ◽  
Yue Lin Qin ◽  
Xiao Wei Liu
Keyword(s):  
Plastic Deformation ◽  
Corrosion Resistance ◽  
Shot Peening ◽  
Electrochemical Impedance ◽  
Corrosion Current ◽  
Optical Microscope ◽  
Microstructure And Properties ◽  
Before And After ◽  
Sever Plastic Deformation ◽  
Evolution Of Microstructure

Plastic deformation can induce surface modification, such as shot peening (SP) on workpiece surface is the hot issue of recent scientific research. SP is the efficient way to improve mechanical behavior of specimens by inducing sever plastic deformation on their surface. Nevertheless, this surface treatment induced complex microstructural evolutions such as grain refinement, will enhance the corrosion resistance of specimens. In this work, the microstructure and properties of 34CrMo4 alloy of before and after SP for 20 min have been investigated. The evolution of microstructure and properties were analyzed from the surface and cross-section. The microstructure morphology at the different depth was determined by optical microscope. The results show grain size is increasing with the depth, and the microhardness and compressive residual stress decrease gradually. In terms of corrosion resistance, the 50 μm depth specimen has the best property than other depth, which the potential and corrosion current density are-0.484 V and-5.72 Acm-2, respectively. The maximum polarization resistance is 2055 Ωcm2by capacitive arc radius of electrochemical impedance spectroscopy.

EFFECT OF TiO2 PARTICLES ON MICRO-HARDNESS, CORROSION, WEAR AND FRICTION OF Ni–P–TiO2 COMPOSITE COATINGS AT DIFFERENT ANNEALING TEMPERATURES

2016 ◽  
Vol 23 (01) ◽  
pp. 1550082 ◽  
Author(s):  
PRASANNA GADHARI ◽  
PRASANTA SAHOO
Keyword(s):  
Wear Resistance ◽  
Corrosion Resistance ◽  
Composite Coatings ◽  
Corrosion Current ◽  
Xrd Analysis ◽  
Charge Transfer Resistance ◽  
Micro Hardness ◽  
Transfer Resistance ◽  
X Ray ◽  
Annealing Temperatures

The present study investigates the effect of titania particles on the micro-hardness, wear resistance, corrosion resistance and friction of electroless Ni–P–TiO2 composite coatings deposited on mild steel substrates at different annealing temperatures. The experimental results confirmed that the amount of TiO2 particles incorporated in the coatings increases with increase in the concentration of particles in the electroless bath. In presence of TiO2 particles, hardness, wear resistance and corrosion resistance of the coating improve significantly. At higher annealing temperature, wear resistance increases due to formation of hard Ni3P phase and incorporation of titania particles in the coated layer. Charge transfer resistance and corrosion current density of the coatings reduce with an increase in TiO2 particles, whereas corrosion potential increases. Microstructure changes and composition of the composite coating due to heat treatment are studied with the help of scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDXA) and X-ray diffraction (XRD) analysis.

The Effect of CN Coatings Doped with Niobium, Titanium and Zirconium Metal on Mechanical, Tribological and Corrosion Resistance Properties of Thin Films

2019 ◽  
Vol 823 ◽  
pp. 81-90 ◽  
Author(s):  
Yen Liang Su ◽  
Wen Hsien Kao ◽  
Yu Chien Chang
Keyword(s):  
Corrosion Resistance ◽  
Wear Rate ◽  
Elastic Recovery ◽  
Chemical Characterization ◽  
Corrosion Current ◽  
Xrd Analysis ◽  
Wear Depth ◽  
Corrosion Properties ◽  
Unbalanced Magnetron Sputtering ◽  
Unbalanced Magnetron

CN-Nb, CN-Ti and CN-Zr that are respectively doped with Nb, Ti and Zr metal in a CN coating are deposited on SKH51 substrate using DC unbalanced magnetron sputtering (DC-UBM). The coatings’ chemical characterization, morphology, mechanical, tribological and corrosion properties are determined. The XRD analysis shows when a low content of metal is added, the coatings exhibit DLC structures. Result from the incorporation of metals, coatings performed denser texture. Simultaneously, the surface became smoother and denser while surface roughness varied from 0.036 to about 0.020 mm. Various properties are improved over CN coating, CN-Ti has a 64% greater hardness at 21.9 Gpa and adhesion 26% better, with a critical load of 87 N. The elastic recovery ranges from 68% (CN) to 100% (CN-Nb and CN-Zr), the wear rate varies from 0.51 10-6mm3/Nm (CN) to 0.1 10-6mm3/Nm (CN-Zr) and the wear depth is reduced by about 73%. An increase in the elastic recovery gives a decreased wear rate. In addition, the corrosion resistance is increased because there is a decrease in the corrosion current density and the CN-Zr coating performed about 35 times better than a CN coating.

Effect of Alkaline Phosphate-Permanganate Conversion Coating on the Corrosion Resistance of AZ91D Magnesium Alloy

2014 ◽  
Vol 974 ◽  
pp. 43-49 ◽  
Author(s):  
Young Min Byoun ◽  
Jin Hwan Jeong ◽  
Jong Kyu Park ◽  
Sun Kyo Seo ◽  
Chi Hwan Lee
Keyword(s):  
Corrosion Resistance ◽  
Magnesium Alloy ◽  
Coating Layer ◽  
Salt Spray ◽  
Xrd Analysis ◽  
Conversion Coating ◽  
Surface And Interface ◽  
Az91d Magnesium Alloy ◽  
Coating Layers ◽  
Alkaline Phosphate

Alkaline phosphate-permanganate conversion coating, chrome-free conversion coating was studied for corrosion resistance of AZ91D magnesium alloy. Also, conventional acid phosphate -permanganate conversion coating was studied for comparison. Analysis and morphology observation for conversion coating layers was investigated in details by using SEM-EDS, XRD. SEM observation showed that a lot of cracks in surface and interface between conversion coating layer and AZ91D magnesium alloy substrate was observed in acid conversion coating, whereas cracks was not almost observed in alkaline conversion coating layer. SEM-EDS and XRD analysis showed that the main elements of both alkaline and acid conversion coating were Mg, O, K, P and Mn. It was found that both conversion coating layers was consisted of MgO, Mg (OH)2and MnO2. Salt spray test showed that the alkaline conversion coating have a good corrosion resistance compared with acid conversion coating.

Micro Arc Oxidation of AZ91 Mg Alloy for Improved Corrosion Resistance

2011 ◽  
Vol 312-315 ◽  
pp. 877-881 ◽  
Author(s):  
H.G. Yavuz ◽  
M. Gunyuz ◽  
Isa Metin Ozkara ◽  
Murat Baydogan ◽  
Huseyin Cimenoglu
Keyword(s):  
Corrosion Resistance ◽  
Surface Topography ◽  
Xrd Analysis ◽  
Processing Parameters ◽  
Mg Alloy ◽  
X Ray Diffraction ◽  
Corrosive Solution ◽  
Weight Losses ◽  
Before And After ◽  
Micro Arc Oxidation

AZ91 Mg alloy was subjected to the micro arc oxidation process by using different processing parameters. Following oxidation, surface topography and qualitative phase analysis were made by tabletop digital microscopy and X-ray diffraction (XRD) analysis. In order to evaluate the relative corrosion resistance of the samples that were oxidized in different parameters, the samples were immersed in a corrosive solution for 6 days and the weight losses before and after the corrosion tests were compared. Relative corrosion resistance of the samples was evaluated on the basis of surface topography.

scholarly journals Evaluation of Electrochemical and Anticorrosion Properties of Polyaniline-Fly Ash Nanocomposite

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Karthika Shetty ◽  
Jayadev ◽  
Kalyan Raj ◽  
H. C. Ananda Murthy
Keyword(s):  
Corrosion Resistance ◽  
Fly Ash ◽  
Mild Steel ◽  
In Situ Polymerization ◽  
Corrosion Current ◽  
Xrd Analysis ◽  
Anticorrosion Property ◽  
Spectroscopic Techniques ◽  
Cyclic Polarization ◽  
Polarization Studies

In India, the thermal station generates approximately 6.9 × 10 7 tons of fly ash (FA) as a waste by-product. As part of this work, little attempt was made to produce useful materials from waste material. In our current research, polyaniline- (PANI-) fly ash (FA) nanocomposite (PFNC) was synthesized using an in situ polymerization method. The synthesized composites were characterized by employing advanced analytical, microscopic, and spectroscopic tools. The results of the X-ray diffraction (XRD) analysis confirm the effective reinforcement of FA into PANI in PFNC. The presence of functional groups in PFNC has been confirmed by Raman and FT-IR spectroscopic techniques. The SEM micrographs of the nanocomposite revealed the presence of agglomerated and fragmented structures in PFNC. The weight loss for PFNC was observed to occur in three stages as revealed by thermogravimetric analysis (TGA). UV-visible spectra for PFNC proved that FA stabilized the PANI in emeraldine form. Electrodynamic polarization studies were conducted to explore the corrosion resistance of nanocomposite-coated mild steel. The corrosion current density ( i corr ) for PFNC-coated mild steel (MS) specimens was found to decrease when compared to the bare substrate, indicating superior corrosion resistance in PFNC-coated substrate. Similarly, Tafel and cyclic polarization studies too confirmed superior anticorrosion property for MS coated with PFNC.

Effects of SnCl4 Concentration on the Properties of Electroless Deposited Ni-Sn-P Coatings

2014 ◽  
Vol 989-994 ◽  
pp. 403-406
Author(s):  
Xi Ran Wang ◽  
Wen Tao Wang ◽  
Bin Yang
Keyword(s):  
Heat Treatment ◽  
Corrosion Resistance ◽  
Deposition Rate ◽  
Corrosion Current ◽  
Polarization Curves ◽  
Surface Appearance ◽  
Positive Direction ◽  
Before And After ◽  
Tin Content

In this paper, the influence of SnCl4concentration on deposition rate, tin content, corrosion resistance and surface appearance of the coating are researched respectively. The results show that SnCl4concentration is increased, deposition rate is increased, then reduced. Tin content in the Ni–Sn–P coatings is increased with increasing SnCl4concentration in the solutions. However, Ni and P contents in the coating is decreased slightly. The microhardness of plating before and after heat treatment is above 500HV. The hardness will be improved a little after heat treatment. With increasing SnCl4concentration, the polarization curves slightly move to positive direction and decrease corrosion current, which shows that the introduction of tin tends to enhance resistance corrosion of the coating. When SnCl4concentration is up to 30g/L, resistant corrosion of the films presents a drop various degrees. The deposits is smooth and uniformity, smooth by SEM and the content of tin is 2.5 to 4.1 percent by EDS.

The importance of phase composition for corrosion resistance and thermal oxidation behavior of gas-borided layer produced on nickel alloy

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Natalia Makuch ◽  
Piotr Dziarski
Keyword(s):  
Corrosion Resistance ◽  
Phase Composition ◽  
Corrosion Current Density ◽  
Oxidation Behavior ◽  
Corrosion Potential ◽  
Corrosion Current ◽  
Xrd Analysis ◽  
Borided Layer ◽  
Effective Barrier ◽  
Corrosion And Oxidation

Abstract Gas boriding was used to produce the borided layer containing a mixture of chromium and nickel borides on the Inconel®600-alloy. The borided sample was characterized by a higher corrosion potential (−0.953 V) than the non-borided sample (−1.005 V). The corrosion current density was significantly lower for the borided sample. The oxidation at 1000 °C for 24 h caused the formation of different oxides on the surface of the borided sample. Simultaneously, the presence of nickel and chromium borides was confirmed by XRD analysis after the oxidation test. It was concluded, that the gas boriding could be an effective barrier against corrosion and oxidation of Inconel®600-alloy.

Role of Aluminium on the Microstructure and Corrosion Behaviour of Magnesium Prepared by Powder Metallurgy Method

2020 ◽  
Vol 17 (3) ◽  
pp. 8206-8213
Author(s):  
J. Alias
Keyword(s):  
Corrosion Resistance ◽  
Powder Metallurgy ◽  
Corrosion Behaviour ◽  
Corrosion Current ◽  
Optical Microscope ◽  
High Reactivity ◽  
Aluminium Content ◽  
Powder Metallurgy Method ◽  
X Ray Diffraction ◽  
Promising Development

Much research on magnesium (Mg) emphasises creating good corrosion resistance of magnesium, due to its high reactivity in most environments. In this study, powder metallurgy (PM) technique is used to produce Mg samples with a variation of aluminium (Al) composition. The effect of aluminium composition on the microstructure development, including the phase analysis was characterised by optical microscope (OM), scanning electron microscopy (SEM) and x-ray diffraction (XRD). The mechanical property of Mg sample was performed through Vickers microhardness. The results showed that the addition of aluminium in the synthesised Mg sample formed distribution of Al-rich phases of Mg17Al12, with 50 wt.% of aluminium content in the Mg sample exhibited larger fraction and distribution of Al-rich phases as compared to the 20 wt.% and 10 wt.% of aluminium content. The microhardness values were also increased at 20 wt.% and 50 wt.% of aluminium content, comparable to the standard microhardness value of the annealed Mg. A similar trend in corrosion resistance of the Mg immersed in 3.5 wt.% NaCl solution was observed. The corrosion behaviour was evaluated based on potentiodynamic polarisation behaviour. The corrosion current density, icorr, is observed to decrease with the increase of Al composition in the Mg sample, corresponding to the increase in corrosion resistance due to the formation of aluminium oxide layer on the Al-rich surface that acted as the corrosion barrier. Overall, the inclusion of aluminium in this study demonstrates the promising development of high corrosion resistant Mg alloys.

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