Effects of Silanes on the Structure and Properties of Chromium-Free Passivation

2020 ◽  
Vol 12 (7) ◽  
pp. 1012-1018
Author(s):  
Fu Haiyang ◽  
Gao Bo ◽  
Zhou Yingwei ◽  
Xing Pengfei
Keyword(s):  
Photoelectron Spectroscopy ◽  
Film Formation ◽  
Resin Composite ◽  
Salt Spray ◽  
Neutral Salt ◽  
Silane Coupling Agents ◽  
Passivation Film ◽  
White Rust ◽  
Steel Surfaces ◽  
Corrosion Of Steel

Steel is one of the most widely used metal materials, and corrosion of steel surfaces is a serious problem. Traditional chromate passivation produces hexavalent chromium with high toxicity and carcinogenicity. To solve toxicity and pollution problems, a chromium-free passivation method was adopted to replace the traditional process. Based on the reaction mechanisms of some silane coupling agents, a new method of chromium-free passivation and anti-white rust production is presented in this paper. The chromium-free passivation process of an inorganic material-silane-resin composite was used in the study. The microstructure and corrosion resistance of a hot-dip galvanized sheet and silane passivation film were compared by using a neutral salt spray test, scanning electron microscopy, infrared spectroscopy and X-ray photoelectron spectroscopy. The mechanism of film formation was studied. The results show that the surface of the passivation film is dense and smooth without sharp protrusions and has a stable skeleton structure inside. The structure of the passive film is C=O, Si–O, C–Si, C–H, Si–O–Zn, Si–O–Si, etc. A chromium-free passivation film prepared with a disilane can effectively prevent penetration between the corrosive medium and matrix. After a 96 h corrosion test, the corrosion area is less than 5%, which meets the requirements of some industrial production processes.

Properties Study of Mixed Silane Films on the Surface of Steel

2014 ◽  
Vol 971-973 ◽  
pp. 135-138
Author(s):  
Zhen Dong Sun ◽  
Yan Ning Yang ◽  
Qing Peng Li ◽  
Jian Guo Liu ◽  
Chuan Wei Yan
Keyword(s):  
Photoelectron Spectroscopy ◽  
Salt Spray ◽  
Adhesive Property ◽  
Epoxy Coating ◽  
Chemical Compositions ◽  
Neutral Salt ◽  
X Ray ◽  
Steel Sheets ◽  
Silane Solution ◽  
Scanning Electron

The mixed silane films were obtained on the surface of the Q235 steel sheets by directly immersing in a mixed silane solution containing γ-Glycidoxypropyltriethoxysilane (γ-GPS) and 1, 2-bis (triethoxysilyl) ethane (BTSE), The chemical compositions and microstructures of the films were examined by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Fourier Transform infrared spectroscopy (FTIR).The corrosion resistances were investigated by electrochemical measurements and neutral salt spray (NSS) test. The effects of silane films to the epoxy coating were investigated through the adhesive property test. The results showed that the γ-GPS/BTSE mixed silane film could remarkably improve the corrosion resistance of epoxy coating and prolong its service life.

scholarly journals Chemical Composition of Corrosion Products of Rebar Caused by Carbonation and Chloride

2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
Author(s):  
Jundi Geng ◽  
Junzhe Liu ◽  
Jiali Yan ◽  
Mingfang Ba ◽  
Zhimin He ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Corrosion Products ◽  
Chloride Salt ◽  
Oxide Content ◽  
Passivation Film ◽  
Steel Bar ◽  
Steel Bars ◽  
Main Components ◽  
Corrosion Of Steel ◽  
Peak Value

The microstructures of steel bars were studied by X-ray photoelectron spectroscopy (XPS), and the mechanism of corrosion of steel bars under the corrosion factors was elucidated. The results show that the passivation film and corrosive surface of the steel surface in the solution of the chloride-containing salt were coarser and the surface state was denser. The main corrosion products are FeOOH and FeO. The surface of the steel immersed in the simulated carbonized solution had loose pores. The main components are FeOOH, Fe3O4, and Fe2O3. The surface of the steel bar has a large amount of yellowish brown corrosion products in the simulated carbonization and chloride salt. The surface of the corrosion products was stripped and the main components are FeOOH, Fe3O4, and FeCl3, where the content of FeOOH is as high as 60%. The peak value of iron is gradually increased from the simulated chloride salt solution to the carbonized solution to the combined effect of carbonation and chloride salt; the iron oxide content is increased and corrosion of steel is obviously serious.

Passivation Effect of Rare Earth Lanthanum on Galvanized Steel

2014 ◽  
Vol 525 ◽  
pp. 31-34
Author(s):  
Xiao Feng Liu
Keyword(s):  
Corrosion Resistance ◽  
Rare Earth ◽  
Electrochemical Impedance ◽  
Orthogonal Experiment ◽  
Salt Spray ◽  
Conversion Coating ◽  
Galvanized Steel ◽  
Neutral Salt ◽  
White Rust ◽  
Order Of Magnitude

By way of chemical marinate method, carrying out rare earth lanthanum to corrosion protect galvanized steel. The process of rare earth lanthanum conversion coating for galvanized steel was studied by using orthogonal experiment to get the optimized passivation parameters when the concentration of La (NO3) is 30g/L, H2O2is 20ml/L, pH=4 and was passivated at 40°C for 30s. The corrosion resistance was examined by weight loss tests, neutral salt spray tests (NSS) and electrochemical impedance spectroscopy (EIS). The results showed that the corrosion impedance of the pretreated sample was significantly improved, the corrosion rate was decreased by one order of magnitude, and the anti-white rust time was 54h.

Research of Organic/Inorganic Chromium-Free Co-Passivation Treatments for Galvanized Steel

2013 ◽  
Vol 785-786 ◽  
pp. 881-886
Author(s):  
Qi Pan ◽  
Lin Wu ◽  
De Lian Yi ◽  
Zhao Hui ◽  
Ou Yang ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Composite Film ◽  
Salt Spray ◽  
Galvanized Steel ◽  
Neutral Salt ◽  
Ac Impedance Spectroscopy ◽  
Good Adhesion ◽  
Passivation Film ◽  
Tafel Polarization ◽  
Inorganic And Organic

The corrosion resistance of chromium-free passivation film with single chromate-free passivation solution to deal with galvanized steel still has a gap compared to chromate passivation. In this experiment, the passivation solution consisting of the inorganic salt as corrosion inhibitor, silane as sealer, water-based epoxy resin and additives which formed a layer of inorganic and organic composite passivation film on galvanized steel through the synergistic effect between inorganic and organic. The morphology and elements of the passivation film was analyzed by scanning electron microscopy (SEM) and the corrosion resistance of the composite film was tested by neutral salt spray test (NSS), lead acetate spot test (ASS), tafel polarization curves and AC impedance spectroscopy (EIS). The results show that the composite film has a good adhesion and an excellent corrosion resistance, the corrosion area is only 3% after 72h NSS.

CORROSION PROTECTION OF ND–FE–B MAGNETS VIA PHOPHATIZATION, SILANIZATION AND ELECTROSTATIC SPRAYING WITH ORGANIC RESIN COMPOSITE COATINGS

2014 ◽  
Vol 21 (06) ◽  
pp. 1450077 ◽  
Author(s):  
XIA DING ◽  
JINGJIE LI ◽  
MUSEN LI ◽  
SHENGSONG GE ◽  
XIUCHUN WANG ◽  
...  
Keyword(s):  
Corrosion Protection ◽  
Permanent Magnets ◽  
Resin Composite ◽  
Composite Coatings ◽  
Energy Dispersive Spectrometer ◽  
Salt Spray ◽  
Neutral Salt ◽  
Electrostatic Spraying ◽  
Silane Coating ◽  
Organic Resin

Nd – Fe – B permanent magnets possess excellent properties. However, they are highly sensitive to the attack of corrosive environment. The aim of this work is to improve the corrosion resistance of the magnets by phosphatization, silanization, and electrostatic spraying with organic resin composite coatings. Field emission scanning electron microscope (FE-SEM) and energy dispersive spectrometer (EDS) tests showed that uniform phosphate conversion coatings and spray layers were formed on the surface of the Nd – Fe – B magnets. Neutral salt spray tests exhibited that, after treated by either phosphating, silanization or electrostatic spraying, the protectiveness of Nd – Fe – B alloys was apparently increased. And corrosion performance of magnets treated with silane only was slightly inferior to those of phosphatized ones. However, significant improvement in corrosion protection was achieved after two-step treatments, i.e. by top-coating spray layer with phosphate or silane films underneath. Grid test indicated that the phosphate and silane coating were strongly attached to the substrate while silane film was slightly weaker than the phosphate-treated ones. Magnetic property analysis revealed phosphatization, silanization, and electrostatic spraying caused decrease in magnetism, but silanization had the relatively smaller effect.

The Corrosion Resistance of Zn-Plated Samples with Blackish Green Passivation Film

2011 ◽  
Vol 383-390 ◽  
pp. 3081-3085
Author(s):  
Yu Bao Cao
Keyword(s):  
Corrosion Resistance ◽  
Electrochemical Impedance ◽  
Salt Spray ◽  
Sample Surface ◽  
Corrosion Current ◽  
Electrochemical Process ◽  
Salt Spray Test ◽  
Neutral Salt ◽  
Passivation Film ◽  
Passivated Sample

The corrosion resistance of blackishgreen passivation films on zinc-plated steel sheet was studied by polarization curve measurement, electrochemical impedance spectroscopy and neutral salt spray test. The passivated sample featured a more positive corrosion potential and much lower corrosion current density as compared to non-passivated sample in 5% (mass fraction) NaCl solution. The Nyquist plots of the samples with and without passivation were characterized as two complete capacitive arcs, indicating that the corrosion is controlled by electrochemical process. The radii of capacitive arcs of the passivated sample are larger than those of non-passivated sample, because the passivation film formed on the sample surface increases the reaction resistance in corrosion process, thus the corrosion resistance of the sample is improved. The anti-white rust time of the passivation film in neutral salt spray test is 400 h.

Study on Chromium-Free Color Passivation for Zinc Coating Treated with Silicate

2010 ◽  
Vol 154-155 ◽  
pp. 1301-1304 ◽  
Author(s):  
Xiao Ke Yang ◽  
Yun Ying Fan ◽  
Ye Hua Jiang ◽  
Zu Lai Li
Keyword(s):  
Hexavalent Chromium ◽  
Salt Spray ◽  
Zinc Coating ◽  
Liquid Composition ◽  
Passive Films ◽  
Neutral Salt ◽  
White Rust ◽  
Zinc Plating ◽  
Zinc Coatings ◽  
Better Than

This paper mainly focuses on how the silicate liquid composition of chromium-free color passivation affects on passivation result, and confirmes the optimum passivation conditions, and uses two zinc plating system of alkaline and acid deposition. Silicate passivation system is compared with hexavalent chromium passivation technology and the results showed that: the appearance and corrosion resistance of passive films formed on zinc coatings plated with alkaline system are better than samples plated with acid system, and have the same corrosion resistanc with hexavalent chromium passivation. The silicate passivation films can keep 200 hours with no white rust in neutral salt spray test.

scholarly journals Effect of sizing agent on interfacial properties of carbon fiber-reinforced PMMA composite

2021 ◽  
Vol 30 ◽  
pp. 2633366X2097865
Author(s):  
Li Jian
Keyword(s):  
Shear Strength ◽  
Surface Treatment ◽  
Photoelectron Spectroscopy ◽  
Resin Composite ◽  
Contact Angles ◽  
Static Contact ◽  
Before And After ◽  
C Value ◽  
Interlayer Shear Strength ◽  
Pmma Resin

The surface treatment of carbon fibers (CFs) was carried out using a self-synthesized sizing agent. The effects of sizing agent on the surface of CFs and the interface properties of CF/polymethyl methacrylate (PMMA) composites were mainly studied. Scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and static contact angle were used to compare and study the CFs before and after the surface treatment, including surface morphology, surface chemical element composition, and wettability of the surface. The influence of sizing agent on the mechanical properties of CF/PMMA resin composite interface was investigated. The results show that after sizing treatment, the CF surface O/C value increased by 35.1% and the contact angles of CF and resin decreased by 16.2%. The interfacial shear strength and interlayer shear strength increased by 12.6%.

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.

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