The Experts below are selected from a list of 273 Experts worldwide ranked by ideXlab platform

Weiping Li - One of the best experts on this subject based on the ideXlab platform.

  • phosphoric Chemical Conversion Coating with excellent wax repellent performance
    Applied Surface Science, 2012
    Co-Authors: Weiping Li, Zhiwei Wang
    Abstract:

    Abstract Wax deposition on pipelines is a serious problem for the production of crude oil. In this paper, phosphoric Chemical Conversion Coatings were exploited to solve the problem. The Chemical Conversion Coatings were fabricated on carbon substrate by surface modification technology at different temperature. A self-designed wax deposition apparatus based on cold-finger was used to study the wax-repellent properties of Coatings, which indicated that all Chemical Conversion Coatings showed superior wax-repellent performance to bare carbon substrate and the wax deposition reduction value of 80–95% was achieved by the Chemical Conversion Coating obtained at room temperature. The microstructure and composition of Coatings were evaluated by SEM and XRD, revealing that there existed much difference in the content of Zn 3 (PO 4 ) 2 (H 2 O) 4 phase and the microstructure among different Coatings. The contact angle results measured on a contact angle meter showed that all Coatings belonged to hydrophilic surface. And the study on the wetting behavior of Zn 3 (PO 4 ) 2 (H 2 O) 4 phase suggested that the water wetting property of Coating was a key factor for suppressing wax deposition and the weak affinity between Coating and wax also played an important role.

  • an excellent non wax stick Coating prepared by Chemical Conversion treatment
    Materials Letters, 2012
    Co-Authors: Weiping Li
    Abstract:

    Abstract The development of non-wax-stick Coating is an important issue for petroleum industry. In this letter, an excellent non-wax-stick Coating was prepared based on Zn Coating by Chemical Conversion treatment. The Chemical Conversion Coating had hydrophilic and superoleophobic properties in water/oil mixture system, which enabled it to trap water molecules on the surface and reduce wax deposition. The Coating was mainly composed of Zn and O elements accompanied by some Si element, and the costing surface showed round bulge structure with different sizes. The combination of Chemical composition and structure was considered to play the key role in the special liquid wettability and non-wax-stick properties.

  • formation mechanism of an aluminium based Chemical Conversion Coating on az91d magnesium alloy
    International Journal of Minerals Metallurgy and Materials, 2010
    Co-Authors: Weiping Li, Ximei Wang, Wen Li
    Abstract:

    An environmentally clean aluminium-based Conversion Coating on AZ91D magnesium alloy was studied in aluminium nitrate solutions. The morphology, composition, structure, and formation mechanism of the Coating were investigated in detail using scanning electron microscopy/energy dispersion spectrometry, X-ray diffraction, transmission electron microscopy, and electroChemical corrosion tests. The results show that the Conversion Coating is composed of magnesium, aluminium, and oxygen, and shows an amorphous structure. In the initial stage of Coating formation, the grain-like nucleus is composed of Al10O15·xH2O, (Al2O3)5.333, Al2O3, AlO(OH), MgAl2O4, (Mg0.88Al0.12)(Al0.94Mg0.06)2O4, and (Mg0.68Al0.32)(Al0.84Mg0.16)2O4. The Conversion Coating formed in the 0.01 mol/L aluminium nitrate solution for 15 min can improve the corrosion resistance of the magnesium alloy greatly. The discussion reveals that the possible formation mechanism for the aluminium-based Conversion Coating is the reduction reaction on micro-cathodic sites due to the electroChemically heterogeneous magnesium alloy substrate.

Peng Tang - One of the best experts on this subject based on the ideXlab platform.

  • investigation of composition and structure for a novel ti zr Chemical Conversion Coating on 6063 aluminum alloy
    Progress in Organic Coatings, 2015
    Co-Authors: Wen-fang Li, Songlin Mu, Jun Du, Yunyu Yang, Peng Tang
    Abstract:

    Abstract A novel Chemical Conversion Coating was prepared by adding tannic acid and Coating-forming accelerator in the treatment solution containing titanium and zirconium ions. Corrosion behavior of the Coatings in contact with 3.5% NaCl solution was investigated using potentiodynamic measurement. The structure and composition of the Coatings were determined with EDS, XPS and IR. The morphologies of the Coatings were observed with scanning electron microscopy (SEM). According to the results, the modified Ti–Zr based Conversion Coating (MTZ) shows a smoother and more compact morphology characterization comparing with the traditional Ti–Zr treated (TZ) substrates; The Tafel results and the long-time immersion experiments also indicate that the MTZ Coating presents a more effective corrosion protection property compared with the TZ Coating; The MTZ Coating is a multi-components Chemical Conversion Coating which is mainly composed of metal oxide (TiO 2 , ZrO 2 , V 2 O 5 , Al 2 O 3 ), fluoride (AlF 3 and ZrF 4 ) and metal–organic complex.

Wen-fang Li - One of the best experts on this subject based on the ideXlab platform.

  • investigation of composition and structure for a novel ti zr Chemical Conversion Coating on 6063 aluminum alloy
    Progress in Organic Coatings, 2015
    Co-Authors: Wen-fang Li, Songlin Mu, Jun Du, Yunyu Yang, Peng Tang
    Abstract:

    Abstract A novel Chemical Conversion Coating was prepared by adding tannic acid and Coating-forming accelerator in the treatment solution containing titanium and zirconium ions. Corrosion behavior of the Coatings in contact with 3.5% NaCl solution was investigated using potentiodynamic measurement. The structure and composition of the Coatings were determined with EDS, XPS and IR. The morphologies of the Coatings were observed with scanning electron microscopy (SEM). According to the results, the modified Ti–Zr based Conversion Coating (MTZ) shows a smoother and more compact morphology characterization comparing with the traditional Ti–Zr treated (TZ) substrates; The Tafel results and the long-time immersion experiments also indicate that the MTZ Coating presents a more effective corrosion protection property compared with the TZ Coating; The MTZ Coating is a multi-components Chemical Conversion Coating which is mainly composed of metal oxide (TiO 2 , ZrO 2 , V 2 O 5 , Al 2 O 3 ), fluoride (AlF 3 and ZrF 4 ) and metal–organic complex.

  • Microstructure and formation mechanism of Ce-based Chemical Conversion Coating on 6063 Al alloy
    Transactions of Nonferrous Metals Society of China, 2009
    Co-Authors: Dong Chu Chen, Wen-fang Li, Wei-hui Gong, Gui-xiang Wu, Jian-feng Wu
    Abstract:

    Abstract In order to accelerate the Conversion Coating formation on 6063 Al alloy in the Ce(NO 3 ) 3 solution, accelerants of chloride and ammonium salt were used. The Coating morphology, composition and structure were analyzed with SEM/EDS, EPMA, XPS and XRD. The Coating morphology is influenced by the composition, pH value and temperature of the treating solution. The Coating composed of metal oxide, metal hydroxide and hydrate appears to be amorphous. The elements in the Coating are Al, Ce, O, Mn and Mg, while the Ce element exists in the forms of Ce 3+ and Ce 4+ . The accelerant of chloride can increase the compactness and Ce content of the Coating, so the Coating corrosion resistance is remarkably improved. A scheme for the electroChemical reaction in the Coating formation was proposed, and the potential change in the Coating formation was also studied. It is found that chloride can shorten the time period of the first and the second stages in Coating formation.

  • A Study of the Environment–Friendly Chrome-Free Chemical Conversion Coating on 2024 Aluminium Alloy
    Materials Science Forum, 2008
    Co-Authors: Dong Chu Chen, Wen Hui Gong, Zhu Zhou Huang, Wen-fang Li
    Abstract:

    In order to develop an environment-friendly method of forming a Chemical Conversion Coating on 2024 aluminium alloy surface without the toxic hexavalent chromium compounds, in this paper a process with sodium molybdate and potassium permanganate as the main compositions of the treating bath has been investigated. Solution composition and process parameters have been optimized. The Chemical Conversion Coating has good corrosion resistance, evaluated with dropping test. Micro-structure and components of the Conversion Coating have been studied by various micro-analysis methods, and the growth mechanism of the Chemical Conversion Coating has also been investigated.

  • Preparing an Environment-Benignly Rare-Earth Based Chemical Conversion Coatings on 6063 Aluminium Alloy
    Key Engineering Materials, 2008
    Co-Authors: Dong Chu Chen, Wen-fang Li, Gui-xiang Wu, Wen Hui Gong, Yiqing Liang
    Abstract:

    In order to develop an environment-benignly Chemical Conversion process to substitute the toxic hexavalent chromium treatment on Al alloy surface, a new surface treatment technology based on rare-earth element, which is to form Chemical Conversion Coating on 6063 Al alloy was presented. In this process, Ce(NO3)3 was adopted in the chrome-free preparing solution, and KMnO4 was used as oxidant to accelerate the Coating formation on 6063 Al alloy. Furthermore, an L16(43) orthogonal experiment was carried out to examine the effect of Ce(NO3)3, KMnO4 and solution temperature on the Coating growth on 6063 Al alloy. Accelerants of SrCl2 and NH4VO3 were added to the preparing solution to improve the Coating performance. XRD, SEM and EDS were used to analyse the Coating surface structure, morphology and composition. It was found that a good anti-corrosion Coating which is mainly composed of the elements of Al, Ce, O, Mn, Mg could be formed in the optimal preparing solution of 5g/L Ce(NO3)3 , 4g/L KMnO4, 1.4g/L SrCl2 at the temperature of 20°C.

S Terauchi - One of the best experts on this subject based on the ideXlab platform.

  • chrome free surface treatments for magnesium alloy
    Surface & Coatings Technology, 2003
    Co-Authors: Hiroyuki Umehara, Matsufumi Takaya, S Terauchi
    Abstract:

    Conversion Coatings for magnesium have traditionally been based on immersion treatment in a solution containing hexavalent chromium compounds. However, the need for a replacement surface treatment has been strongly emphasized by the present environmental drive to eliminate hexavalent chromium. The development of permanganate bath Chemical Conversion Coatings for magnesium alloys was studied, using mass gain measurements, measurements of corrosion potential, X-ray diffraction, X-ray photoelectron spectroscopy and microscopic examination. The Chemical Conversion Coating obtained from a permanganate bath consists of a film, composed mainly of manganese oxides and magnesium oxide or hydroxide. Such films were found to be amorphous composite Coatings. The corrosion resistance of permanganate Chemical Conversion Coatings was comparable with that of chromating.

Musen Li - One of the best experts on this subject based on the ideXlab platform.

  • influence of bath ph value on microstructure and corrosion resistance of phosphate Chemical Conversion Coating on sintered nd fe b permanent magnets
    Journal of Magnetism and Magnetic Materials, 2016
    Co-Authors: Xia Ding, Xiuchun Wang, Kaihong Ding, Musen Li
    Abstract:

    Abstract The effect of bath PH value on formation, microstructure and corrosion resistance of the phosphate Chemical Conversion (PCC) Coatings as well as the effect on the magnetic property of the magnets is investigated in this paper. The results show that the Coating mass and thickness increase with the decrease of the bath PH value. Scanning electron microscopy observation demonstrates that the PCC Coatings are in a blocky structure with different grain size. Transmission electron microscope and X-ray diffractometer tests reveal the Coatings are polycomponent and are mainly composed of neodymium phosphate hydrate and praseodymium phosphate hydrate. The electroChemical analysis and static immersion corrosion test show the corrosion resistance of the PCC Coatings prepared at bath PH value of 0.52 is worst. Afterwards the corrosion resistance increases first and then decreases with the increasing of the bath PH values. The magnetic properties of all the samples with PCC treatment are decreased. The biggest loss is occurred when the bath PH value is 0.52. Taken together, the optimum PH range of 1.00–1.50 for the phosphate solution has been determined.