Nanocomposite TiAlBN Coatings as a Corrosion Protection Layer for AZ91 Mg Alloy Substrate in NaCl

2015 ◽  
Vol 819 ◽  
pp. 109-114 ◽  
Author(s):  
M.R. Zulkifli ◽  
Muhammad Zaimi ◽  
Jariah Mohamad Juoi ◽  
Zainab Mahamud

Magnesium alloys create increasing interest in structural application where weight reduction is vast concern. However, one of magnesium drawback in various applications is low corrosion resistance. In general, a hard coating can be applied on metal to combat such a problem. AlN and TiN coatings are most widely utilized in manufacturing area i.e for structural application due to its high hardness, high chemical stability, and excellent adhesion to substrates. Most recent, TiAlBN coating catch many attentions due to its superior properties than other most studied hard coating. The incorporation of aluminium in the cubic face centered TiN structure on Ti sites leads to deformation and strengthening of the crystal structure of the coating together. Moreover, incorporation of BN in this coating should improve and enhanced the corrosion resistance of Mg alloy. Therefore, in this study, TiAlBN coating have been chosen to be deposited on Mg alloy using reactive magnetron sputtering together with AlN and TiN coatings for comparison study. During depositions, target power, working pressure and bias voltage are optimized for each coating. Analysis on the effect of AlN, TiN and TiAlBN coatings on Mg alloy substrate include thickness measurement and microstructure by scanning electron microscope (SEM). Coatings phase were analysed using glancing angle X-ray diffraction analysis (GAXRD) and corrosion properties were evaluated using potentiodynamic polarization in NaCl solution. TiAlBN shows better performance of corrosion protection with the least corrosion rate (penetration rate = 0.20 mm/yr; mass loss rate=0.97g/m2d) in sodium chloride (NaCl) solution although having the lowest coating thickness (412 nm).

2005 ◽  
Vol 12 (03) ◽  
pp. 417-424
Author(s):  
X. P. ZHANG ◽  
G. CHEN

Immersion and electrochemical tests have been applied to study corrosion protection of AZ91D Mg alloy coating with chrome-free chemical conversion (CCC) coat in 5wt% NaCl solution. The immersions tests include weight-loss measurements after full or partial immersion with whole coating and full immersion with damaged coating. The electrochemical tests include electrochemical impedance spectroscopy (EIS) and polarization curves measurement. The results of immersion and electrochemical tests show that chrome-free chemical conversion (CCC) surface treatment can significantly improve the corrosion resistance of AZ91D Mg alloy in 5% NaCl solution, and that the corrosion protection effect of CCC coating is not sensitive to pores or cracks. The equivalent circuit models are fitted from Nyquist plots for the uncoated specimens and the CCC-coated specimens. The charge transfer resistance, R ct , increases from about 1.669 Ω cm2 for the uncoated alloy to about 210 Ω cm2 after the alloy is coated with CCC coating.


Vacuum ◽  
2014 ◽  
Vol 108 ◽  
pp. 61-65 ◽  
Author(s):  
M. Daroonparvar ◽  
M.A.M. Yajid ◽  
H.R. Bakhsheshi-Rad ◽  
N.M. Yusof ◽  
S. Izman ◽  
...  

2017 ◽  
Vol 11 (2) ◽  
pp. 91-95 ◽  
Author(s):  
Eliza Romańczuk ◽  
Zbigniew Oksiuta

AbstractIn this work two austenitic stainless steels, REX734 and 316LV were tested in terms of their microstructure and corrosion properties. The REX734 is a newer generation stainless steel, with modified chemical composition, in comparison to the 316LV grade. Potentiodynamic study of corrosion resistance was conducted in physiological saline solution (0.9% NaCl solution). In spite of the similarities of microstructure, grain size and phase structure in both materials, the corrosion tests revealed that the REX734, with lower nickel and higher nitrogen content, had better corrosion resistance than 316LV. Repassivation potential in the REX734 was almost six times higher than for the 316LV steel. Superior corrosion resistance of the REX734 steel was also confirmed by surface observations of both materials, since bigger and more densely distributed pits were detected in 316LV alloy.


Metals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 167 ◽  
Author(s):  
Omid Khalaj ◽  
Ehsan Saebnoori ◽  
Hana Jirková ◽  
Ondřej Chocholatý ◽  
Jiří Svoboda

Fe–Al–O-based materials are currently undergoing a great deal of development because of their many special properties. However, lack of strength at high temperatures, limited ductility at ambient temperatures and corrosion resistance have hindered a wider application of these materials. Recently, a new Fe–Al-based oxide precipitation hardened (OPH) steel was developed by the authors to improve the mechanical properties and oxidation resistance. The new OPH alloys are produced by dissolving a specific amount of oxygen in the matrix during mechanical alloying followed by precipitation of fine dispersion of aluminum or yttrium oxides during hot consolidation. A series of tests was performed to evaluate the thermomechanical properties and corrosion resistance in a 3.5% NaCl solution. The results show improved corrosion resistance, as well as mechanical properties, while the production costs of this material are lower than for traditional materials.


RSC Advances ◽  
2015 ◽  
Vol 5 (1) ◽  
pp. 706-716 ◽  
Author(s):  
F. Ansari ◽  
R. Naderi ◽  
C. Dehghanian

An eco-friendly silane sol–gel coating incorporating nanoclay was formulated to provide an effective corrosion protection for stainless steel 304L in a NaCl solution.


2019 ◽  
Vol 9 (9) ◽  
pp. 1092-1099
Author(s):  
Fenghong Cao ◽  
Chang Chen ◽  
Zhenyu Wang

The corrosion characteristics and corrosion mechanism of the extruded ZK80 alloy with different states soaking in 3.5% NaCl solution at room temperature were analyzed via OM, SEM, EDS, XRD and static weightlessness method and other experimental analysis methods. The results show that when the aging temperature is constant, and the corrosion rate decreases with the lengthen of aging time, while when the corrosion time is constant, the corrosion rate increases with the increase in aging time. Appropriate aging treatment not only refines the grain of the alloy, but also precipitates the Mg–Zn phase which can effectively prevent the corrosion process and improve the anti-corrosion properties of the alloy. The main corrosion characteristics of the alloy are filamentary corrosion and pitting corrosion.


Materials ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2647
Author(s):  
Madiha Ahmed ◽  
Yuming Qi ◽  
Longlong Zhang ◽  
Yanxia Yang ◽  
Asim Abas ◽  
...  

The objectives of this study were to reduce the corrosion rate and increase the cytocompatibility of AZ31 Mg alloy. Two coatings were considered. One coating contained MgO (MAO/AZ31). The other coating contained Cu2+ (Cu/MAO/AZ31), and it was produced on the AZ31 Mg alloy via microarc oxidation (MAO). Coating characterization was conducted using a set of methods, including scanning electron microscopy, energy-dispersive spectrometry, X-ray photoelectron spectroscopy, and X-ray diffraction. Corrosion properties were investigated through an electrochemical test, and a H2 evolution measurement. The AZ31 Mg alloy with the Cu2+-containing coating showed an improved and more stable corrosion resistance compared with the MgO-containing coating and AZ31 Mg alloy specimen. Cell morphology observation and cytotoxicity test via Cell Counting Kit-8 assay showed that the Cu2+-containing coating enhanced the proliferation of L-929 cells and did not induce a toxic effect, thus resulting in excellent cytocompatibility and biological activity. In summary, adding Cu ions to MAO coating improved the corrosion resistance and cytocompatibility of the coating.


2018 ◽  
Vol 5 (10) ◽  
pp. 172410 ◽  
Author(s):  
Jinhe Dou ◽  
Yupeng Zhao ◽  
Lu Lu ◽  
Guochao Gu ◽  
Huijun Yu ◽  
...  

The applications of magnesium (Mg) alloys as biodegradable orthopedic implants are mainly restricted due to their rapid degradation rate in the physiological environment. In this study, Si–CaP micro-arc oxidation (MAO) coatings were prepared on a Mg–Zn–Ca alloy by a second-step MAO process at different voltages in order to decrease the degradation rate and increase the bioactivity of the alloy. The microstructure and morphology of the samples were characterized using XRD, FT-IR SEM and EDS. The degradation behaviours of samples were evaluated using electrochemical techniques, and immersion tests in simulated body fluid (SBF). The results indicate that the morphology of the Si–CaP coatings changed significantly with the increase in Ca/P ratio as the second-step voltage increased. The Si–CaP containing coating produced at 450 V could significantly decrease the degradation rate of Mg and caused a slow increase in pH of the SBF solution. The haemolysis test concluded that the coating C3 did not cause a haemolytic reaction. The corrosion resistance of Mg alloy was greatly improved with the Si–CaP coatings, and the Mg alloy with Si–CaP coating prepared at 450 V had the best corrosion resistance, which indicates that the Si–CaP coatings are promising for improving the biodegradation properties of Mg-based orthopedic implants. Haemolysis tests indicated that the Si–CaP coating prepared at 450 V conforms to the given standard (YY/T0127.1-93).


Metals ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 765 ◽  
Author(s):  
Dan Song ◽  
Jinghua Jiang ◽  
Xiaonan Guan ◽  
Yanxin Qiao ◽  
Xuebin Li ◽  
...  

Surface nano-crystallization (SNC) of a conform-extruded Cu-0.4 wt.% Mg alloy was successfully conducted by high-speed rotating wire-brushing to obtain the deformed zone with dislocation cells and nanocrystallines. SNC promotes the anodic dissolution and corrosion rate of the Cu-Mg alloy in the initial stage of immersion corrosion in 0.1 M NaCl solution. The weakened corrosion resistance is mainly attributed to the higher corrosion activity of SNC-treated alloy. With extending the immersion time, the SNC-treated alloy slows the corrosion rate dramatically and exhibits uniform dissolution of the surface. The formation of the dense corrosion products leads to the improvement of overall corrosion performance. It indicates that the SNC-treated Cu-Mg alloy can function reliably for a longer duration in a corrosive environment.


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