The Experts below are selected from a list of 11751 Experts worldwide ranked by ideXlab platform

G. E. Thompson - One of the best experts on this subject based on the ideXlab platform.

  • corrosion protection mechanism of 2 mercaptobenzothiazole and its potential synergistic effect with cerium ions for treatment of aa 2024 t3
    Journal of Electroanalytical Chemistry, 2020
    Co-Authors: A C Balaskas, Michele Curioni, G. E. Thompson
    Abstract:

    Abstract The corrosion protection mechanism of 2-mercaptobenzothiazole (2-MBT) and its potential synergistic effect with cerium chloride (CeCl3) for sustainability of the Aerospace Alloy AA 2024-T3 was investigated. The corrosion inhibitors 2-MBT and CeCl3 and their potential synergistic properties were assessed with image-assisted electrochemical noise, the split-cell technique, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM) observations. It is suggested that 2-MBT inhibits the deAlloying of S-phase particles and prevents the formation of Cu-rich particles on the surface of AA 2024-T3. 2-MBT protects the second phase particles from corrosion and offers sustainability in 3.5% NaCl solution by formation of a protective layer on the surface of AA 2024-T3. Additionally, 2-MBT is adsorbed on the surface of AA 2024-T3 during anodic dissolution of aluminium. A synergistic effect between 2-MBT and the Ce3+ based corrosion inhibitor was not found. It is suggested that 2-MBT protects the intermetallic particles from corrosion from the early immersion time and blocks the precipitation of cerium hydroxides over the second phase particles. 2-MBT revealed better corrosion protection properties compared with CeCl3 and 2-MBT + CeCl3 in the tested time scale.

  • two shell structured pmaa ceo2 nanocontainers loaded with 2 mercaptobenzothiazole for corrosion protection of damaged epoxy coated aa 2024 t3
    Nanoscale, 2017
    Co-Authors: A C Balaskas, Michele Curioni, T Hashimoto, G. E. Thompson
    Abstract:

    In this work, novel two-shell structured inhibitor-loaded poly(methacrylic acid)@cerium oxide (PMAA@CeO2) nanocontainers were synthesised and characterized. The purpose of the nanocontainers is to increase the corrosion protection provided by an epoxy coating applied to an Aerospace Alloy (AA 2024-T3). The (PMAA@CeO2) nanocontainers with diameters of 550 nm were synthesised by a four-step process with the method of distillation precipitation polymerization for the synthesis of the inner PMAA layer, and the sol-gel method for the development of the outer CeO2 layer. The loaded nanocontainers were characterized by scanning and transmission electron microscopies. The corrosion protection properties of the epoxy coated AA 2024-T3 with 2-mercaptobenzothiazole (2-MBT) loaded PMAA@CeO2 nanocontainers were evaluated with and without artificial scribes by electrochemical impedance spectroscopy (EIS). The results indicated that the epoxy coating containing the 2-MBT-loaded nanocontainers provided enhanced protection of the AA 2024-T3 substrate.

  • influence of molybdate species on the tartaric acid sulphuric acid anodic films grown on aa2024 t3 Aerospace Alloy
    Corrosion Science, 2009
    Co-Authors: Michele Curioni, G. E. Thompson, M Garciarubio, P Ocon, A Climentfont, R W Smith, A Lavia, Ignacio Garcia
    Abstract:

    AA2024 T3 Alloy specimens have been anodised in tartaric acid/sulphuric media and tartaric acid/sulphuric media containing sodium molybdate; molybdate species were added to the anodising bath to enhance further the protection provided by the porous anodic film developed over the macroscopic Alloy surface. Morphological characterisation of the anodic films formed in both electrolytes was undertaken using scanning electron and transmission electron microscopies; the chemical compositions of the films were determined by Rutherford backscattering spectroscopy that was complemented by elemental depth profiling using rf-glow discharge optical emission spectrometry. The electrochemical behaviour was evaluated using potentiodynamic polarisations and electrochemical impedance spectroscopy; the corrosion performance was examined after salt spray testing. The porous anodic film morphology was little influenced by the addition of molybdate salt, although thinner films were generated in its presence. Chemical composition of the anodic film was roughly similar; however, addition of sodium molybdate in the anodizing bath resulted in residues of molybdate species in the porous skeleton and improved corrosion resistance measured by electrochemical techniques that was confirmed by salt spray testing.

I A Palani - One of the best experts on this subject based on the ideXlab platform.

  • performance of laser surface textured high speed steel cutting tool in machining of al7075 t6 Aerospace Alloy
    Surface & Coatings Technology, 2017
    Co-Authors: Roshan Sasi, Kanmani S Subbu, I A Palani
    Abstract:

    Abstract Texturing the rake face of the cutting tools has recently emerged as a promising and environment friendly method for reducing friction during machining. Laser surface texturing has been the most commonly used method for fabricating textures on the cutting tool. This paper reports the experimental study of fabricating an array of micro scale dimples on the rake face of high speed steel cutting tool using a pulsed Nd:YAG laser. The effect of the laser parameters like wavelength and fluence on the dimensions and form of individual dimples were studied. Analysis of results show that uniform circular shaped dimples with very little spatter can be obtained using low fluence levels at wavelength of 355 nm. An array of micro scale dimples were then fabricated on the cutting tool using the optimized parameter levels. A very low textured area density was used in order to understand the process of chip flow over the textures and study the effect of machining on individual dimples. This textured cutting tool was then used in orthogonal dry machining of Al7075-T6 Aerospace Alloy and compared with the performance of conventional tools. Use of textured cutting tools resulted in reduction of both cutting and thrust forces. The tool-chip contact length is also less in the case of textured tool. The results show that textured high speed steel tools can significantly improve the metal cutting process while dry machining ductile workpieces.

Safian Sharif - One of the best experts on this subject based on the ideXlab platform.

  • cutting performance and wear characteristics of pvd coated and uncoated carbide tools in face milling inconel 718 Aerospace Alloy
    Journal of Materials Processing Technology, 2001
    Co-Authors: A Jawaid, Sakip Koksal, Safian Sharif
    Abstract:

    In this paper, cutting performance and failure characteristics of two PVD TiN coated and an uncoated tungsten carbide grades with identical geometry are presented. Face-milling tests of Inconel 718 superAlloy were performed to investigate the effect of cutting speed and feed rate on tools performance under wet conditions. Tools were thoroughly examined under SEM at two stages in order to reveal the failure modes and wear mechanisms. These stages were after cutting for 5 s and when the tool failed. It was noted that the coating resulted in a marginal improvement, as it was delaminated by adhering workpiece material at the beginning of the cut, impeding the performance of the tool for the rest of the experiment. A combination of progressive chipping and flank wear was the general mode of tool failure, former being dominant at high speeds and the latter at the low speed region. Results showed that uncoated tool performed better than coated tools at low cutting speeds while coated tools gave slightly better performance as the speed was raised.

Michele Curioni - One of the best experts on this subject based on the ideXlab platform.

  • corrosion protection mechanism of 2 mercaptobenzothiazole and its potential synergistic effect with cerium ions for treatment of aa 2024 t3
    Journal of Electroanalytical Chemistry, 2020
    Co-Authors: A C Balaskas, Michele Curioni, G. E. Thompson
    Abstract:

    Abstract The corrosion protection mechanism of 2-mercaptobenzothiazole (2-MBT) and its potential synergistic effect with cerium chloride (CeCl3) for sustainability of the Aerospace Alloy AA 2024-T3 was investigated. The corrosion inhibitors 2-MBT and CeCl3 and their potential synergistic properties were assessed with image-assisted electrochemical noise, the split-cell technique, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM) observations. It is suggested that 2-MBT inhibits the deAlloying of S-phase particles and prevents the formation of Cu-rich particles on the surface of AA 2024-T3. 2-MBT protects the second phase particles from corrosion and offers sustainability in 3.5% NaCl solution by formation of a protective layer on the surface of AA 2024-T3. Additionally, 2-MBT is adsorbed on the surface of AA 2024-T3 during anodic dissolution of aluminium. A synergistic effect between 2-MBT and the Ce3+ based corrosion inhibitor was not found. It is suggested that 2-MBT protects the intermetallic particles from corrosion from the early immersion time and blocks the precipitation of cerium hydroxides over the second phase particles. 2-MBT revealed better corrosion protection properties compared with CeCl3 and 2-MBT + CeCl3 in the tested time scale.

  • two shell structured pmaa ceo2 nanocontainers loaded with 2 mercaptobenzothiazole for corrosion protection of damaged epoxy coated aa 2024 t3
    Nanoscale, 2017
    Co-Authors: A C Balaskas, Michele Curioni, T Hashimoto, G. E. Thompson
    Abstract:

    In this work, novel two-shell structured inhibitor-loaded poly(methacrylic acid)@cerium oxide (PMAA@CeO2) nanocontainers were synthesised and characterized. The purpose of the nanocontainers is to increase the corrosion protection provided by an epoxy coating applied to an Aerospace Alloy (AA 2024-T3). The (PMAA@CeO2) nanocontainers with diameters of 550 nm were synthesised by a four-step process with the method of distillation precipitation polymerization for the synthesis of the inner PMAA layer, and the sol-gel method for the development of the outer CeO2 layer. The loaded nanocontainers were characterized by scanning and transmission electron microscopies. The corrosion protection properties of the epoxy coated AA 2024-T3 with 2-mercaptobenzothiazole (2-MBT) loaded PMAA@CeO2 nanocontainers were evaluated with and without artificial scribes by electrochemical impedance spectroscopy (EIS). The results indicated that the epoxy coating containing the 2-MBT-loaded nanocontainers provided enhanced protection of the AA 2024-T3 substrate.

  • influence of molybdate species on the tartaric acid sulphuric acid anodic films grown on aa2024 t3 Aerospace Alloy
    Corrosion Science, 2009
    Co-Authors: Michele Curioni, G. E. Thompson, M Garciarubio, P Ocon, A Climentfont, R W Smith, A Lavia, Ignacio Garcia
    Abstract:

    AA2024 T3 Alloy specimens have been anodised in tartaric acid/sulphuric media and tartaric acid/sulphuric media containing sodium molybdate; molybdate species were added to the anodising bath to enhance further the protection provided by the porous anodic film developed over the macroscopic Alloy surface. Morphological characterisation of the anodic films formed in both electrolytes was undertaken using scanning electron and transmission electron microscopies; the chemical compositions of the films were determined by Rutherford backscattering spectroscopy that was complemented by elemental depth profiling using rf-glow discharge optical emission spectrometry. The electrochemical behaviour was evaluated using potentiodynamic polarisations and electrochemical impedance spectroscopy; the corrosion performance was examined after salt spray testing. The porous anodic film morphology was little influenced by the addition of molybdate salt, although thinner films were generated in its presence. Chemical composition of the anodic film was roughly similar; however, addition of sodium molybdate in the anodizing bath resulted in residues of molybdate species in the porous skeleton and improved corrosion resistance measured by electrochemical techniques that was confirmed by salt spray testing.

M S I Chowdhury - One of the best experts on this subject based on the ideXlab platform.

  • wear performance investigation of pvd coated and uncoated carbide tools during high speed machining of tial6v4 Aerospace Alloy
    Wear, 2020
    Co-Authors: M S I Chowdhury, Jose Mario Paiva, L S Shuster, Bipasha Bose, K Yamamoto, Stephen C Veldhuis
    Abstract:

    Abstract Selection of hard PVD coatings for the machining of Ti6Al4V Alloy should be based on the dominant tool wear mechanism and tribological phenomena occurring at the chip-tool-workpiece interface. The present work investigates the effect of AlTiN and CrN hard coatings on the wear performance of cemented carbide cutting tools during high-speed finish turning of Ti6Al4V. The wear characteristics of the tools were evaluated by SEM and 3D wear volume measurements. The in-situ tribological performance of the coatings was characterized by chip morphology analysis, in combination with coefficient of friction measurements using a high temperature/heavy load tribometer that mimics actual machining conditions. Micro-mechanical characteristics of the coatings were also studied in detail. The results obtained show that the application of a CrN coating significantly improves tool performance due to a combination of the micro-mechanical properties of the coating and the tribological characteristics of the surface engineered layer.

  • tribological and wear performance of carbide tools with tib2 pvd coating under varying machining conditions of tial6v4 Aerospace Alloy
    THE Coatings, 2017
    Co-Authors: Jose Mario Paiva, M A Shalaby, M S I Chowdhury, L S Shuster, Sergey Chertovskikh, Danielle Covelli, Edinei Locks, Pietro Stolf, Amr Elfizy, Carlos Alberto Schuch Bork
    Abstract:

    Tribological phenomena and tool wear mechanisms during machining of hard-to-cut TiAl6V4 Aerospace Alloy have been investigated in detail. Since cutting tool wear is directly affected by tribological phenomena occurring between the surfaces of the workpiece and the cutting tool, the performance of the cutting tool is strongly associated with the conditions of the machining process. The present work shows the effect of different machining conditions on the tribological and wear performance of TiB2-coated cutting tools compared to uncoated carbide tools. FEM modeling of the temperature profile on the friction surface was performed for wet machining conditions under varying cutting parameters. Comprehensive characterization of the TiB2 coated vs. uncoated cutting tool wear performance was made using optical 3D imaging, SEM/EDX and XPS methods respectively. The results obtained were linked to the FEM modeling. The studies carried out show that during machining of the TiAl6V4 Alloy, the efficiency of the TiB2 coating application for carbide cutting tools strongly depends on cutting conditions. The TiB2 coating is very efficient under roughing at low speeds (with strong buildup edge formation). In contrast, it shows similar wear performance to the uncoated tool under finishing operations at higher cutting speeds when cratering wear predominates.

  • wear behaviour of coated carbide tools during machining of ti6al4v Aerospace Alloy associated with strong built up edge formation
    Surface & Coatings Technology, 2017
    Co-Authors: M S I Chowdhury, G K Dosbaeva, Amr Elfizy, Bipasha Bose, K Yamamoto, Shahereen Chowdhury, Ben D Beake, D Cavelli, Maryam Aramesh, G S Foxrabinovich
    Abstract:

    Abstract In the machining of Ti Alloys, it is challenging to optimise the cutting tool life and process productivity. It is not a trivial task to find an efficient strategy to improve the tool life during machining of Ti Alloys using surface engineered tooling. In the case of rough turning operation with strong built up edge formation we establish that it can be achieved through the application of self-lubricating TiB 2 PVD coating. It has been shown that the application of a TiB 2 coating results in tool life improvement by over 60% compared to the uncoated tool and over 70% compared to the TiAlN coated tool. Comprehensive characterization of the coated vs. uncoated cutting tool wear performance was performed using optical 3D imaging, SEM/EDX and XPS methods. Various micro-mechanical characteristics of the TiB 2 coating were evaluated. It was determined that tool life improvement using the TiB 2 coating is mostly related to the ability of the coating layer to provide self-lubrication effect and in this way, very efficiently dissipate frictional energy. The coating also exhibited less substrate exposure as it fails indicating better protection of the coated tool surface. This is of particular importance for machining of materials like Ti, which have strong sticking intensity. It has been demonstrated that the TiB 2 coating combines beneficial micro-mechanical characteristics and self-lubricating properties due to the formation of B-O tribo-films on the tool surface under operation. These tribo-films serve as a liquid lubricant formed in-situ on the tool surface under the elevated temperature of cutting. The formation of liquid tribo-films is an effective way to address intensive adhesive interaction followed by built up edge formation at the tool/chip interface, which is typical for roughing operations during Ti machining.