scholarly journals Effects of temperature and pH value on the morphology and corrosion resistance of titanium-containing conversion coating

2021 ◽  
Vol 3 ◽  
pp. 100060
Author(s):  
Junfeng Gou ◽  
Mingren Sun ◽  
Xinxin Ma ◽  
Guangze Tang ◽  
Yongkang Zhang
Keyword(s):  
Corrosion Resistance ◽  
Ph Value ◽  
Conversion Coating ◽  
Effects Of Temperature

Study on Preparation and the Characteristics of Environment-Friendly Ce-Ti-Mn Conversion Coating on Aluminum Alloy 6061

2014 ◽  
Vol 881-883 ◽  
pp. 1385-1390
Author(s):  
Xian Fang Yang ◽  
Tian Quan Liang ◽  
Wei Wei ◽  
Dong Hui Deng ◽  
Guang Qiao Xu ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Aluminum Alloy ◽  
Room Temperature ◽  
Ph Value ◽  
Conversion Coating ◽  
Environment Friendly ◽  
Aluminum Alloy 6061 ◽  
Coating Characteristics ◽  
Surface Morphologies ◽  
Alloy 6061

Preparation and the characteristics of environment-friendly Ce-Ti-Mn conversion coating on aluminum alloy 6061 were investigated by XRD, FESEM, EDS, TEM and AFM in this paper. It is indicated that coating characteristics such as the surface morphologies, microstructure and corrosion resistance, are greatly influenced by the formation technology at room temperature. The constituents and their concentration, and pH value of the conversion solution have an important role on the feature of Ce-Ti-Mn conversion film, which will significantly influence on the continuity, compactness and the crystalline structure of particles of the film. The concentrations of the main salt K2TiF6and oxidizer KMnO4have significant effect on the characteristics of the conversion coating. The Ce-Ti-Mn film grows in a lamellar way, composing of oxide and/ or hydroxide phases of Ce, Ti and Mn, some of which are amorphous. The formation mechanism of the Ce-Ti-Mn conversion coating is discussed in detail.

Influencing Factors of Phytic Acid Conversion Coating on AZ91 Magnesium Alloy

2011 ◽  
Vol 239-242 ◽  
pp. 2336-2341
Author(s):  
Yan Ling Lu ◽  
Yan Kun Chen ◽  
Shi Guo Du ◽  
Yi Guo ◽  
Qing Hong
Keyword(s):  
Corrosion Resistance ◽  
Magnesium Alloy ◽  
Phytic Acid ◽  
Acid Concentration ◽  
Ph Value ◽  
Conversion Coating ◽  
Metal Corrosion ◽  
Anode Current Density ◽  
Az91 Magnesium Alloy ◽  
Az91 Magnesium

AZ91 magnesium alloy is selected as the matrix metal. SEM, EDS, Tafel and EIS were adopted and spot test was carried out to investigate the influence of pH value, phytic acid concentration, temperature,conversion time on corrosion resistance of conversion coatings. Result shows that process of phytic acid forming is the controlled metal corrosion process and the uneven surface pattern reflects the different chemical properties of two-phase current on magnesium alloy surface, which is implied by the conversion surface. It is proved by the test that pH value is committed the most to the corrosion resistance of the conversion coating, and the next is the phytic acid concentration. It is found that the corrosion resistance of the conversion coating is the best when pH value of the conversion solution is 4.5; The conversion coating has little influence on the cathode reaction dynamics, however, more importantly, it changes the dynamics of the alloy electrode anode solution reaction, therefore, the alloy’s anode current density decreases while the corrosion resistance of magnesium alloy is enhanced.

scholarly journals Design and Multidimensional Screening of Flash-PEO Coatings for Mg in Comparison to Commercial Chromium(VI) Conversion Coating

Metals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 337
Author(s):  
Ewa Wierzbicka ◽  
Marta Mohedano ◽  
Endzhe Matykina ◽  
Raul Arrabal
Keyword(s):  
Corrosion Resistance ◽  
Corrosion Protection ◽  
Electrochemical Impedance ◽  
Salt Spray ◽  
Conversion Coating ◽  
Neutral Salt ◽  
Chromium Vi ◽  
Alkaline Electrolytes ◽  
Az31b Alloy ◽  
Plasma Electrolytic

REACH (Registration, Evaluation, Authorisation and Restriction of Chemicals) regulations demand for an expedient discovery of a Cr(VI)-free alternative corrosion protection for light alloys even though the green alternatives might never be as cheap as current harmful technologies. In the present work, flash- plasma electrolytic oxidation coatings (FPEO) with the process duration < 90 s are developed on AZ31B alloy in varied mixtures of silicate-, phosphate-, aluminate-, and fluoride-based alkaline electrolytes implementing current density and voltage limits. The overall evaluation of the coatings’ anticorrosion performance (electrochemical impedance spectroscopy (EIS), neutral salt spray test (NSST), paintability) shows that from nine optimized FPEO recipes, two (based on phosphate, fluoride, and aluminate or silicate mixtures) are found to be an adequate substitute for commercially used Cr(VI)-based conversion coating (CCC). The FPEO coatings with the best corrosion resistance consume a very low amount of energy (~1 kW h m−2 µm−1). It is also found that the lower the energy consumption of the FPEO process, the better the corrosion resistance of the resultant coating. The superb corrosion protection and a solid environmentally friendly outlook of PEO-based corrosion protection technology may facilitate the economic justification for industrial end-users of the current-consuming process as a replacement of the electroless CCC process.

scholarly journals CO2 mineralization by olivine at hydrothermal conditions

2014 ◽  
Vol 78 (6) ◽  
pp. 1473-1477
Author(s):  
Jan Přikryl ◽  
Andri Stefánsson
Keyword(s):  
Ph Value ◽  
Hydrothermal Conditions ◽  
Solution Ph ◽  
Rock Interaction ◽  
Carbonate Formation ◽  
Effects Of Temperature ◽  
Co2 Mineralization ◽  
Geochemical Reaction ◽  
Insight Into ◽  
Water Rock Interaction

The interaction of CO2-rich water with olivine was studied using geochemical reaction modelling in order to gain insight into the effects of temperature, acid supply (CO2) and extent of reaction on the secondary mineralogy, water chemistry and mass transfer. Olivine (Fo93) was dissolved at 150 and 250ºC and pCO2 of 2 and 20 bar in a closed system and an open system with secondary minerals allowed to precipitate. The progressive water–rock interaction resulted in increased solution pH, with gradual carbonate formation starting at pH 5 and various Mg-OH and Mg-Si minerals becoming dominant at pH>8. The major factor determining olivine alteration is the pH of the water. In turn, the pH value is determined by acid supply, reaction progress and temperature.

The Study about Environmentally-Friendly Passivation Technology Process and Performance on Brass Surface

2011 ◽  
Vol 399-401 ◽  
pp. 1967-1971
Author(s):  
Hong Yin Xu ◽  
Li Li
Keyword(s):  
Corrosion Resistance ◽  
Phytic Acid ◽  
Passive Film ◽  
Ph Value ◽  
Sodium Molybdate ◽  
Solution Ph ◽  
Sulfosalicylic Acid ◽  
Passivation Film ◽  
Brass Surface ◽  
And Performance

The paper through the synergy before mixed Phytic acid and Sodium molybdate, Sulfosalicylic acid, Organic silane, and add the active substances PEG, Optimize the Passivation liquid formula of Brass surface, Phytic acid is the main ingredient, study the affection of Phytic acid Passive film Corrosion resistance on the three main Passivation conditions: Passivation temperature, time and Passivation solution PH value. The results show that，Phytic acid passivation film process recipes as follows：Phytic acid (quality score 50%) 2~5ml/L, sodium molybdate 4~8g/L, organic material 10~30ml/L, sulfosalicylic acid 3~7g/L, polyethylene glycol 2~6g/L, deactivated temperature 30~35°C, pH value 5, deactivated time 60s. The test showed that，the phytic acid passive film can obviously enhance the anti-corrosive performance on the brass surface, its corrosion resistance proportion chromates passive film is fairly good.

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