Influences of current density on structure and corrosion resistance of ceramic coatings on Ti–6Al–4V alloy by micro-plasma oxidation

2004 ◽  
Vol 468 (1-2) ◽  
pp. 120-124 ◽  
Author(s):  
Zhongping Yao ◽  
Zhaohua Jiang ◽  
Xuetong Sun ◽  
Shigang Xin ◽  
Yanping Li
Keyword(s):  
Corrosion Resistance ◽  
Current Density ◽  
Ceramic Coatings ◽  
Plasma Oxidation

Influences of Duty Ratio on Structure and Corrosion Resistance of Ceramic Coatings on Ti-6Al-4V by Micro-Plasma Oxidation

2007 ◽  
Vol 336-338 ◽  
pp. 2454-2457
Author(s):  
Hong Qi Ben ◽  
Zhong Ping Yao ◽  
Zhao Hua Jiang
Keyword(s):  
Corrosion Resistance ◽  
Outer Layer ◽  
Oxidation Process ◽  
Ceramic Coatings ◽  
Duty Ratio ◽  
Plasma Oxidation ◽  
Rutile Tio2 ◽  
Key Factor ◽  
Α Al2o3 ◽  
Better Than

Duty ratio is a key factor during micro-plasma oxidation process. Its influences on structure and corrosion resistance of ceramic coatings on Ti–6Al–4V by pulsed bi-polar MPO in NaAlO2 solution were investigated. The ceramic coatings were composed of Al2TiO5, α-Al2O3 and rutile TiO2, of which Al2TiO5 was the main crystalline. The coating can be divided into a porous outer layer and a dense inner layer. Compared with the condition of the same duty ratio for both pulses, the rise of anode duty ratio (D1) led to an increase in the amount of Al2TiO5 and α-Al2O3 and increased the thickness of the coating; whereas the rise of cathode duty ratio (D2) led to a decrease in the amount of α-Al2O3 and decreased the thickness of the coating. Besides, the corrosion resistance of the coated samples was better than that of Ti-6Al-4V substrate. When D1 / D2 = 60 / 30, the produced coating’s corrosion resistance was best.

Effect of Current Density on the Microstructure and Corrosion Properties of MAO Coatings on Aluminum Alloy Shock Absorber

2018 ◽  
Vol 764 ◽  
pp. 28-38 ◽  
Author(s):  
Yan Shen ◽  
Hong Xiang Wang ◽  
Yi Peng Pan
Keyword(s):  
Corrosion Resistance ◽  
Aluminum Alloy ◽  
Current Density ◽  
Shock Absorber ◽  
Structural Characteristics ◽  
Ceramic Coatings ◽  
Corrosion Performance ◽  
Cathode Voltage ◽  
Corrosion Properties ◽  
Micro Arc Oxidation

In order to improve the corrosion resistance of shock absorber for ships, the alumina ceramic coatings are carried out on the surface of aluminum alloy shock absorber by micro arc oxidation (MAO) technology. The microstructure and anti-corrosion performance of the MAO coatings were investigated experimentally. This paper mainly focuses on the experimental work to determine the effect of current density on the structural characteristics and corrosion resistance of MAO coatings. The results show that the current density has a significant influence on the preparation of MAO coating during the process. The surface of the coating becomes more compact and smooth with the cathode voltage of 7 A.dm-2. Furthermore, the anti-corrosion performance of the MAO coatings can effectively be improved at the current density of 7 A.dm-2.

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.

Laser Sintering of Nano-Al2O3 Powders on Plasma Sprayed Ceramic Based Coatings

2007 ◽  
Author(s):  
Lida Shen ◽  
Yinhui Huang ◽  
Zongjun Tian ◽  
Guoran Hua
Keyword(s):  
Wear Resistance ◽  
Corrosion Resistance ◽  
Plasma Spraying ◽  
Bond Coat ◽  
Continuous Wave ◽  
Ceramic Coatings ◽  
Laser Sintering ◽  
Al2o3 Ceramic ◽  
Plasma Sprayed ◽  
Steel Substrates

This paper describes an investigation of nano-Al2O3 powders reinforced ceramic coatings, which has included NiCrAl and Al2O3+13%wt.TiO2 coats pre-produced by atmosphere plasma spraying, implemented by laser sintering. Commercial NiCrAl powders were plasma sprayed onto 45 Steel substrates to give a bond coat with thickness of ∼100μm. The 600μm thick Al2O3+13%wt.TiO2 based coating was also plasma sprayed on top of the NiCrAl bond coat. With 2.5kw continuous wave CO2 laser, nano-Al2O3 ceramic powders were laser sintered on the based Coatings. The micro structure and chemical composition of the modified Al2O3+13%wt.TiO2 coatings were analyzed by such detection devices as scanning electronic microscope (SEM) and x-ray diffraction (XRD). Microhardness, wear resistance and corrosion resistance of the modified coatings were also tested and compared with that of the unmodified. The results show that the crystal grain size of Al2O3 had no obvious growth. In addition, due to the nanostructured Al2O3 ceramic phases, the coatings exhibited higher microhardness, better wear resistance and corrosion resistance than those unmodified counterparts. The complex process of plasma spraying with laser sintering as a potential effective way of the application of ceramic nano materials was also simply discussed and summarized in the end.

Influences of Calcination Ambiences on Phase Composition and High Temperature Oxidation Resistance Property of Ceramic Coatings on Ti–6Al–4V Alloy by Micro-Plasma Oxidation

2007 ◽  
Vol 336-338 ◽  
pp. 2481-2483 ◽  
Author(s):  
Guo Dong Hao ◽  
Zhao Hua Jiang ◽  
Zhong Ping Yao ◽  
Heng Ze Xian ◽  
Yan Li Jiang
Keyword(s):  
Phase Composition ◽  
High Temperature ◽  
Oxidation Resistance ◽  
High Temperature Oxidation ◽  
Ceramic Coatings ◽  
Plasma Oxidation ◽  
Temperature Oxidation ◽  
Complete Decomposition ◽  
Weight Gains ◽  
High Temperature Calcination

Compound ceramic coatings with the main crystalline of Al2TiO5 (as-coated samples) were prepared on Ti-6Al-4V alloy by pulsed bi-polar micro-plasma oxidation (MPO) in NaAlO2 solution. The coated samples were calcined in Ar and air at 1000oC, respectively. The phase composition, morphology and element content of the coatings were investigated by XRD, SEM and XRF. The samples treated in Ar and the as-coated ones were calcined in air at 1000oC to study the oxidation resistance of the samples. The results showed that Al2TiO5 decomposed and transformed into corundum and rutile TiO2 during the high temperature calcination. Al2TiO5 decomposed very quickly in air and the proportion of Al2O3 to TiO2 was 44:55 after a complete decomposition. On the contrary, Al2TiO5 decomposed very slowly in argon with the final proportion of Al2O3 to TiO2 of 81:18 on the coating surface. The morphology of the ceramic coatings after the calcination was also different. The coatings calcined in argon were fined: the grains and pores were smaller than those of the coatings calcined in air. The weight gains of both coatings changed in the form of parabola law, and the weight gains of the coated samples treated in argon were comparatively lower than that of the as-coated samples. During the high temperature calcination, the samples treated in argon cannot distort easily, compared with the as-coated ones.

scholarly journals Corrosion Behavior of AA 1100 Anodized in Gallic-Sulfuric Acid Solution

Coatings ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 405
Author(s):  
Marlon L. Mopon ◽  
Jayson S. Garcia ◽  
Dexter M. Manguerra ◽  
Cyril John C. Narisma
Keyword(s):  
Corrosion Resistance ◽  
Sulfuric Acid ◽  
Acid Solution ◽  
Gallic Acid ◽  
Acid Concentration ◽  
Sulfuric Acid Solution ◽  
Current Density ◽  
Electrochemical Impedance ◽  
Anodized Aluminum ◽  
The Common

Sulfuric acid anodization is one of the common methods used to improve corrosion resistance of aluminum alloys. Organic acids can be added to the sulfuric acid electrolyte in order to improve the properties of the anodized aluminum produced. In this study, the use of gallic acid as an additive to the sulfuric acid anodization of AA1100 was explored. The effect of varying anodization current density and gallic acid concentration on the properties of anodized aluminum samples was observed using electrochemical impedance spectroscopy, linear polarization, and scanning electron microscopy. It was observed that the corrosion resistance of samples anodized in gallic-sulfuric acid solution at 10 mA·cm−2 is lower than samples anodized in sulfuric acid. It was also observed that higher anodization current density can lead to lower corrosion resistances for aluminum samples anodized in gallic-sulfuric acid solution. However, samples anodized at 5 mA·cm−2 and at a gallic acid concentration of 5 g·L−1 showed better corrosion performance than the samples anodized in sulfuric acid only. This suggests that the use of low amounts of gallic acid as an additive for sulfuric acid anodization can lead to better corrosion resistances for anodized aluminum.

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