Phosphate and Stannate Chemical Conversion Coatings Formed on AZ91D Alloys

2009 ◽  
Vol 610-613 ◽  
pp. 1407-1413 ◽  
Author(s):  
Xiang Jie Yang ◽  
Hua Lan Jin
Keyword(s):  
Phase Composition ◽  
Chemical Conversion ◽  
Conversion Coating ◽  
Conversion Coatings ◽  
X Ray Diffraction ◽  
Alloy Matrix ◽  
Β Phase ◽  
Before And After ◽  
Loss Method ◽  
Better Than

The morphology and the mass change of the AZ91D alloys matrix after pretreatment, the morphology and the phase composition of chemical conversion coatings formed by phosphate and stannate were studied using scanning electron microscope, X-ray diffraction and the mass loss method. The corrosion resistance of the coatings were studied by salt spay test and damp heat test. The results show that the phase composition of matrix before and after pretreatment is almost changeless and the mass diminishes a litter, the deep micro flaw appears near between α-Mg and β phase during acidic pickling. The phosphate chemical conversion coating is mainly composed of Mg, MgO and some amorphous phase, and the stannate conversion coating is crystal structure and mainly composed of Mg, Al12Mg17 and MgSnO3•3H2O. Results from salt spay test and damp heat test indicate that the two coatings also can provide good protection for the magnesium alloy matrix, and stannate is better than phosphate.

Structure and Corrosion Resistance of Tin Salt Conversion Coating on Aluminum Alloy

2010 ◽  
Vol 129-131 ◽  
pp. 467-471
Author(s):  
Yan Bo Wu ◽  
Si Si Zeng ◽  
Peng Sun
Keyword(s):  
Corrosion Resistance ◽  
Chemical Conversion ◽  
Conversion Coating ◽  
Spherical Particles ◽  
X Ray Diffraction ◽  
Uncoated Sample ◽  
X Ray ◽  
Coating Composition ◽  
Chemical Conversion Coating ◽  
Better Than

A chrome-free chemical conversion coating was prepared using stannous sulfate as the main salt. The morphology of the chemical conversion surface layer was observed by scanning electron microscopy (SEM). Coating composition and the microcosmic phase structure were characterized using energy dispersive X-ray (EDX) analysis and X-ray diffraction (XRD) respectively. Electrochemical method and dropping test were used to study the coatings corrosion resistance. The results indicated that the tin salts conversion coating is a crystal structure material that composites with Sn-F-O-Al et al., the surface appears as a accumulation of spherical particles, the crystallinity of conversion coating is better than uncoated sample obviously, the corrosion resistance has improved too.

Comparison of Two Different Chemical Conversion Coating on Aluminum Alloy

2010 ◽  
Vol 146-147 ◽  
pp. 208-211
Author(s):  
Yan Bo Wu ◽  
Si Si Zeng ◽  
Peng Sun
Keyword(s):  
Corrosion Resistance ◽  
Aluminum Alloy ◽  
Electrochemical Method ◽  
Chemical Conversion ◽  
Conversion Coating ◽  
Conversion Coatings ◽  
X Ray Diffraction ◽  
Surface Layers ◽  
X Ray ◽  
Chemical Conversion Coating

In this paper, we made two different chemical conversion coatings on aluminum alloy by TiOSO4 and Na2WO4. The morphology of the chemical conversion surface layers were observed by scanning electron microscopy (SEM). The microcosmic phase structures were characterized using X-ray diffraction (XRD). Electrochemical method was used to study the coatings corrosion resistance. The results indicated that the two conversion coatings were crystal structure material, the surface of coating were both show pothole structure. TiOSO4 coating have better corrosion resistance than Na2WO4 coating.

Properties of Conversion Coating of Magnesium Alloys by a Phosphate-Permanganate Solution

2005 ◽  
Vol 488-489 ◽  
pp. 665-668 ◽  
Author(s):  
Shu Sen Wu ◽  
Ming Zhao ◽  
Ji Rong Luo ◽  
You Wu Mao
Keyword(s):  
Corrosion Resistance ◽  
Magnesium Alloys ◽  
Adhesion Force ◽  
Conversion Coating ◽  
Resistance Test ◽  
Az91d Alloy ◽  
Conversion Coatings ◽  
Good Adhesion ◽  
Better Than

A chromium-free conversion coating for AZ91D magnesium alloys has been obtained by using a phosphate-permanganate solution. Examinations have been carried out on the conversion coating for morphology, composition, adhesion force and corrosion resistance. Results show that the conversion coatings are relatively uniform and continuous, with thickness from 7µm to 10µm. They exhibit good adhesion to matrix and have some non-penetrate tiny holes on the surface. The main elements of the conversion coating of AZ91D alloy are Mg、O、P、K、Al、Mn. Results of corrosion resistance test indicate that the corrosion resistance of the conversion coating by phosphate-permanganate solution is in match to that of the conversion coating formed in a chromate solution, but for the corrosion resistance after painting, the former is better than the later.

Zirconate Conversion Coatings on Al Alloy by Electrochemical Method

2012 ◽  
Vol 460 ◽  
pp. 86-89
Author(s):  
Qi Zhou ◽  
Hong Yan Liu ◽  
Xiu Lian Cheng ◽  
Guang Sen Zhang
Keyword(s):  
Corrosion Resistance ◽  
Paint Film ◽  
Chemical Conversion ◽  
First Grade ◽  
Conversion Coating ◽  
Complexing Agents ◽  
Complexing Agent ◽  
Al Alloy ◽  
Conversion Coatings ◽  
Electrochemical Conversion

Chromium-free conversion coatings were generated to replace chromate chemical process by electrolysis treatment LY12 aluminum alloy in zirconate solution. Film thickness, dropping test, the adhesion between aluminum and paint film were tested for single-factor experiments and orthogonal to seek better electrolysis process. The paint adhesion is the first grade for electrochemical conversion solution containing complexing agents, or it is the second grade without complexing agents. When DNS complexing agent is 2 ~ 5g/L, film corrosion resistance rises with the increasing content of complexing agent. If voltage is too low, corrosion resistance of conversion coating is poor; voltage is too high, the films form powders. Better formulations for zirconate conversion coating are: 5g/L DNS complexing agent, 10V voltage, treatment temperature is 40°C. Electrochemical conversion coating is thinner than chemical conversion, but the corrosion resistance is better because the electrochemical conversion coatings are smoother and compacter than the chemical conversion coating. The paint films on electrochemical conversion coating are smoother than the chemical one. Two kinds of conversion coatings have very good adhesion with paint film up to the first level. Electrochemical conversion coatings thickness is 2.5 μm, bubble time of NaOH-glycerine solution on them is up to 92s.

Novel Strontium Doped Zinc Calcium Phosphate Conversion Coating on AZ31 Magnesium Alloy for Biomedical Applications

2017 ◽  
Vol 34 ◽  
pp. 57-67 ◽  
Author(s):  
P. Amaravathy ◽  
T.S. Sampath Kumar
Keyword(s):  
Magnesium Alloy ◽  
Calcium Phosphate ◽  
Chemical Conversion ◽  
Conversion Coating ◽  
Az31 Magnesium Alloy ◽  
Degree Of Crystallinity ◽  
X Ray Diffraction ◽  
X Ray ◽  
Simple Chemical ◽  
High Degree

A simple chemical conversion coating was adopted to deposit zinc calcium phosphate (ZCP) coating and strontium doped ZCP (SZCP) coating on AZ31 magnesium alloy to induce biocompatibility and reduce the degradation rate. The surface morphology, chemical composition and functional groups of the coating were characterized by Scanning Electron Microscopy with Energy Dispersive X-Ray Spectroscopy (SEM-EDS), X-Ray Diffraction (XRD) studies and Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) spectroscopy respectively. SZCP coating formed at 20 min deposition time produced crack free surface with a high degree of crystallinity with barrier property, which ultimately retards the dissolution of magnesium in Simulated Body Fluid (SBF). The corrosion resistance of AZ31 magnesium alloy was improved by SZCP coating as evident from hydrogen evolution test (HET). Cytotoxicity evaluation with L969 cells showed that Sr doped ZCP coatings showed less toxicity on resorbable magnesium alloys.

Effect of Heat Treatment on Microstructures and Properties of AZ40M Alloy

2016 ◽  
Vol 849 ◽  
pp. 173-180 ◽  
Author(s):  
Lin Lai ◽  
Kui Zhang ◽  
Ming Long Ma ◽  
Guo Liang Shi
Keyword(s):  
Magnesium Alloy ◽  
Second Phase ◽  
X Ray Diffraction ◽  
Homogenization Treatment ◽  
Homogenization Process ◽  
Β Phase ◽  
Before And After ◽  
The Matrix ◽  
Tensile Fractures ◽  
Tensile Experiment

The influence of two-step homogenization on microstructures and properties of AZ40M magnesium alloy were investigated by the scanning electronic microscopy (SEM), X-ray diffraction analysis (XRD) and tensile experiment. Through comparing the microstructure and mechanical properties of the alloy before and after homogenization treatment, a two-step homogenization process of the semi-continuous casting AZ40M magnesium alloy ingot was determined. The result shows that the as-cast AZ40M alloy mainly contained two kinds of second phase, β-Mg17Al12 and Al8Mn5. Treating at temperature of 380 °C for 8 h as the first step homogenization treatment and then treating at temperature of 420 °C for 20 h as the second step homogenization treatment made the eutectic phase (α-Mg/β-Mg17Al12) completely eliminated and the alloying elements such as Al, Zn distributed uniformly. Al8Mn5 is the residual second phase in the homogenized AZ40M alloy. During the homogenization process, the β-phase dissolved which made the content of Al increased in the matrix. The decomposition of β-phase benefits the tensile strength and elongation of the alloy. The tensile fractures of as-cast and homogenization alloys are characteristic of ductile fracture.

scholarly journals Acid Black 194 Dye Clarifications Onto Natural And Acid/Base Activated Smectitic Clays

2021 ◽  
Author(s):  
Salima Chakroun ◽  
Haitham Elleuch ◽  
Dalel Sghaier ◽  
Mohamed Gaied
Keyword(s):  
Surface Area ◽  
Dye Adsorption ◽  
Effluent Treatment ◽  
Acid Activation ◽  
X Ray Diffraction ◽  
Optimum Result ◽  
Batch System ◽  
Before And After ◽  
Activation Conditions ◽  
Better Than

Abstract The present work is concerned the Acid Black 194 dye adsorption by Two smectitic clays (BJ and AJ) aged upper Eocene were sampled from Atlas Central of Tunisia in Kairouan region. Technical characterization was carried out using calcimetry and X-ray diffraction. The activation studies of clays by HCl/ Na2CO3 have been conducted to improve their physicochemical properties. The optimum result of the surface area after acid activation (aa) was 398 m2/g for BJ aa and AJ aa, after basic activation (ab) the surface area was 460 m2 /g for BJ ab and 440 m2/g for AJ ab. The characterization by XRD, chemical analysis and SEM observations, were performed before and after optimum activation.Moreover, the raw and activated samples (aa/ab) under the optimum activation conditions were used in the effluent treatment. Adsorption tests were made by batch system at 25 °C in different pH (2-12) and by varying the adsorbent amount (0.025-0.1 g). The best adsorption results were recorded with pH = 11 and amount adsorbent 0.025 g. The raw clay adsorption capacity was slightly better than activated samples. The best yield was given by BJ (94%). Therefore, clay can be used in various applications without any characteristic modification.

scholarly journals Chemical conversion of a solid body of the composite gypsum/polyhydroxybutyrate in hydroxyapatite/polyhydroxybutyrate

Cerâmica ◽  
2019 ◽  
Vol 65 (375) ◽  
pp. 335-339
Author(s):  
A. A. Barbosa ◽  
S. A. Júnior ◽  
A. C. S. Dantas ◽  
A. V. Ferraz
Keyword(s):  
Ammonium Hydroxide ◽  
Chemical Conversion ◽  
Ph Control ◽  
Raw Material ◽  
Added Value ◽  
X Ray Diffraction ◽  
Before And After ◽  
Ammonium Hydrogen ◽  
Diffraction Patterns ◽  
Clear Change

Abstract The transformation of the gypsum into hydroxyapatite allows added value to this raw material, because the ceramic obtained has a high commercial value in relation to gypsum, while the polymer adds biocompatibility and bioactivity properties to the biocomposite. Thus, hydroxyapatite/polyhydroxybutyrate composites were prepared from the gypsum/polyhydroxybutyrate, using a 10% mass ratio of the polymer. The material was obtained by means of a chemical conversion carried out in a solution of ammonium hydrogen phosphate (0.5 mol.L-1) and alkaline medium (ammonium hydroxide 6.0 mol.L-1) for pH control. The reaction occurred at 100 °C at different test times. Analyzes of infrared spectroscopy showed functional groups characteristic of hydroxyapatite after 36 h of reaction; in addition, the biomaterial was identified as the major phase in X-ray diffraction patterns. Scanning electron microscopy of the materials before and after conversion showed a clear change in their morphologies, indicating the success of the synthesis.

scholarly journals Leachability and Stability of Hexavalent-Chromium-Contaminated Soil Stabilized by Ferrous Sulfate and Calcium Polysulfide

2018 ◽  
Vol 8 (9) ◽  
pp. 1431 ◽  
Author(s):  
Ting-Ting Zhang ◽  
Qiang Xue ◽  
Ming-Li Wei
Keyword(s):  
Hexavalent Chromium ◽  
Contaminated Soil ◽  
Ferrous Sulfate ◽  
X Ray Diffraction ◽  
Factors Affecting ◽  
X Ray ◽  
Acid Buffering ◽  
Before And After ◽  
Calcium Polysulfide ◽  
Better Than

Ferrous sulfate (FeSO4) and calcium polysulfide (CaS5) stabilization are practical approaches to stabilizing hexavalent chromium (Cr(VI))-contaminated soil. The leachability and stability of Cr(VI) and Cr are important factors affecting the effectiveness of stabilized Cr(VI)-contaminated soil. This study compared the leachability and stability of Cr(VI) and Cr in Cr(VI)-contaminated soil stabilized by using FeSO4 and CaS5. The contaminated soil was characterized before and after stabilization, and the effectiveness of FeSO4 and CaS5 stabilization was assessed using leaching, bioaccessibility, alkaline digestion, sequential extraction, and X-ray diffraction tests. Results showed that FeSO4 and CaS5 significantly reduced the leachability and Cr(VI) content in the contaminated soil. The acid-buffering capacity and stability (leachability, bioaccessibility, speciation distribution, and mineral composition) of the Cr(VI)/Cr and Cr(VI) content of CaS5 were better than those of FeSO4. This study demonstrated that CaS5 had a better effect than FeSO4 on the stabilization of Cr(VI) in Cr(VI)-contaminated soil. The CaS5 significantly enhanced the stabilization and immobilization of Cr(VI) and reduced its leachability and toxicity.

Biodegradability of AZ31B Magnesium Alloy with a Permanganate Conversion Coating

2014 ◽  
Vol 707 ◽  
pp. 163-167
Author(s):  
Si Yu Wu ◽  
Qiang Guo Chen ◽  
Jing Jing Xu ◽  
Ting Ting Yan ◽  
Qing Hua Chen
Keyword(s):  
Magnesium Alloy ◽  
Corrosion Property ◽  
Conversion Coating ◽  
Biodegradable Material ◽  
X Ray Diffraction ◽  
Energy Dispersion Spectroscopy ◽  
Alloy Matrix ◽  
Az31b Magnesium Alloy ◽  
X Ray ◽  
Micro Cracks

Magnesium alloy has been considered as a revolutionary biodegradable material, but the fast degradation limits its development. A permanganate conversion coating for AZ31B magnesium alloy prepared, in order to improve its anti-corrosion property. The morphology and composition of the coating were characterized with scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersion spectroscopy (EDS), which showed that the coating was 40-170μm in thickness, with net-like micro-cracks, and was tightly combined with AZ31B magnesium alloy matrix. The main compositions of the coating were Mg and a series of oxides of Mn. Observed by the tests of electrochemical and immersion,the corrosion resistance of AZ31B magnesium alloy can be improved significantly through the permanganate conversion treatment

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