Corrosion Protection Of Surfaces Research Articles

Surface corrosion protection designing of particulate electromagnetic material towards self-healable functional composite

The electromagnetic wave active carbonyl iron (CI) particles were susceptible to environmental damage leading to functionality loss. Polymeric network as surface coating layer of CI appeared to be useful for improving their anti-corrosion ability. It is also expected that the coating could bridge the particles and the polymer matrix when CI was applied in polymer composites so that the integrity can be promoted. In the present work, disulfide bond [-S-S-] and 2-ureido-4-pyrimidinone (UPy) containing monomers were adopted for formation of crosslinked protection layer (named EAU layer) of CI. The EAU layer significantly enhanced the electrochemical corrosion resistance of CI based on the results of impedance modulus (0.01 Hz), potentiodynamic polarization test, and long term (200 cycles) cyclic voltammetry test. The CI-EAU could also retain good microwave absorbing ability. It is also found that when CI-EAU was embedded in synthesized polyurethane with dynamic [-S-S-] bond and UPy moieties. The composite could achieve fast self-healing under laser irradiation in the presence of Mxene. Besides, the composite was recyclable and could move the cargo under magnetic field. This well-designed strategy holds great promise not only for effective corrosion protection of electromagnetic functional particles, but also for realization of stable and self-healable electromagnetic composites.

Corrosion Resistance and Thermal Conductivity Enhancement of Reduced Graphene Oxide-BaSO4-Epoxy Composites.

The results of studies on the corrosion protectiveness and thermal conductivity of reduced graphene oxide–BaSO4 epoxy composites are reported here. A commercial epoxy resin and reduced graphene oxide (rGO) were blended with a hardening reagent and then mixed with prepared BaSO4–epoxy resin (B–epoxy). The reduced graphene oxide–BaSO4–epoxy composite (rGO–B–epoxy) paste was used to coat the surfaces of Al 7205 alloy and the corrosion and thermal properties were investigated. A corrosion test in a 3.5 wt% synthetic sea water solution showed that the composite coating containing BaSO4 had the best corrosion resistance. Moreover, the rGO–B–epoxy composite showed better protection against corrosion than the epoxy alone. The rGO–B–epoxy composite with 5 wt% BaSO4 had an in-plane coefficient of thermal conductivity of approximately 165.0 W/m K, and the in-plane thermal diffusivity was 71.38 mm2/s. In standard thermal conductivity tests, all three samples had values below 40 W/m K. The rGO–B–epoxy composites showed good surface corrosion protection and in-plane thermal conductivity.

Optimized polymer coating for magnesium alloy-based bioresorbable scaffolds for long-lasting drug release and corrosion resistance

Magnesium (Mg) alloy-based bioresorbable scaffolds (BRSs) are attracting interest as next-generation stents. However, because medical Mg alloy materials degrade relatively quickly in physiological media, surface corrosion protection via biodegradable polymer coatings is important for clinical applications. Herein, the influence of biodegradable polymer coatings on the BRS corrosion was investigated. First, elution of the drug sirolimus (SRL) from various biodegradable polymers was estimated, including poly(d,l-lactic acid) (PDLLA), poly(d,l-lactic acid-co-ε-caprolactone) (PLCL) and poly(ε-caprolactone) (PCL). Among these, the PDLLA polymer exhibited the slowest release and the best character as a drug reservoir because of its slow degradation rate and semi-glass state in a biological environment. However, the corrosion rate of the PDLLA-coated Mg alloy (AZ31)-based platform was as rapid as the non-coated platform, while critical defects, cracking and desorption were observed in the PDLLA layer. Coatings comprising PCL and PLCL exhibited a prolonged platform corrosion resistance compared with that of PDLLA. To combine the advantages of each polymer, therefore, a pre-coating of PCL or PLCL was applied to the interface between the platform and the external SRL-loaded PDLLA layer. This layering exhibited an enhanced platform corrosion resistance, and will be an important foundational procedure for the development of a coronary scaffold comprising magnesium alloys.

Bioresorbable scaffolds are here, please handle with care

Magnesium (Mg) alloy-based bioresorbable scaffolds (BRSs) are attracting interest as next-generation stents. However, because medical Mg alloy materials degrade relatively quickly in physiological media, surface corrosion protection via biodegradable polymer coatings is important for clinical applications. Herein, the influence of biodegradable polymer coatings on the BRS corrosion was investigated. First, elution of the drug sirolimus (SRL) from various biodegradable polymers was estimated, including poly(d,l-lactic acid) (PDLLA), poly(d,l-lactic acid-co-ε-caprolactone) (PLCL) and poly(ε-caprolactone) (PCL). Among these, the PDLLA polymer exhibited the slowest release and the best character as a drug reservoir because of its slow degradation rate and semi-glass state in a biological environment. However, the corrosion rate of the PDLLA-coated Mg alloy (AZ31)-based platform was as rapid as the non-coated platform, while critical defects, cracking and desorption were observed in the PDLLA layer. Coatings comprising PCL and PLCL exhibited a prolonged platform corrosion resistance compared with that of PDLLA. To combine the advantages of each polymer, therefore, a pre-coating of PCL or PLCL was applied to the interface between the platform and the external SRL-loaded PDLLA layer. This layering exhibited an enhanced platform corrosion resistance, and will be an important foundational procedure for the development of a coronary scaffold comprising magnesium alloys.

Residual Stress in Coatings Produced by Cold Spray

Cold spray technology is used to produce metal coatings with a variety of functions, including surface corrosion protection, improvement of wear resistance, etc. Cold sprayed materials exhibit a wide range of behaviours resulting in large variation of spraying efficiency, coating properties, quality and performance in service. Residual stress, being a result and attribute of the deposition process, can be studied to test whether the coating is in tension/compression stress state and also to provide information about the thermo-mechanical history of the material during the deposition process. Residual stress distributions in a variety of coating materials have been studied by neutron diffraction. Through-thickness residual stress profiles show that the stress magnitude varies significantly and depends mainly on the mechanical properties of the coating material.

High Productivity Combinatorial Analysis of Cu Post-CMP Cleans: Corrosion Protection and Queue Time

High Productivity Combinatorial (HPC) technology was used to evaluate post-CMP clean chemistries and their impact on copper surface corrosion protection and queue time performance. Cleaning formulations at low pH and high pH, both with and without functional additives, were used to produce a wide range of surface conditions typical in semiconductor processing. X-ray photoelectron spectroscopy (XPS) results show that low pH cleans remove most oxides, but that within 20 hrs copper oxide re-growth occurs in the form of Cu (I) and Cu (II) oxide species. Electrochemical analysis is a simpler and higher throughput method to study oxide growth over time. Good agreement existed between electrochemical and XPS techniques when both were used to study copper surfaces for 0 to 20 hours after clean. The electrochemical tests were continued after 48 hours of queue time to develop a better understanding of oxide growth trends, and showing continued oxidation of Cu surfaces treated with low pH cleans. For extremely long queue times, SEM analysis shows growth of visible copper oxide nodules on Cu lines and pads for low pH treated M1 test structures. Leakage of comb structures monitored as a function of queue time was inconsistent, indicating that standard leakage measurements at 1V for comb structures with 0.125 / 0.175 line/space dimensions are not sensitive to the copper surface instability of oxidation.

Large area laser surface treatment of aluminium alloys for pitting corrosion protection

Laser surface treatment has been recognised as a useful method for corrosion protection of surfaces as a result of improved microstructure/phase formation and compositions. In large area applications, overlapping of individual tracks corresponding to the width of the laser beam is often necessary. This involves re-melting and re-heating of a portion of the previous track and results in microstructural changes, such as precipitate coarsening and microsegregation, which may influence localised corrosion at the overlapped regions. The purpose of this work is to investigate the influence of overlapped regions on corrosion behaviour of laser-melted aluminium 2014-T6 alloy. Laser melting was carried out using a 3 kW CW Nd:YAG laser with a line beam profile. The microstructures of the central part and the overlapped region of the melt pool were examined using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). Pitting corrosion resistance was evaluated using potentiodynamic anodic polarisation in 1 M NaCl solution. The work revealed enhancement of the pitting potential by 170 mV compared with that of the untreated alloy, similar to that achieved by laser surface melting with a CO 2 laser in a Gaussian mode. The line beam profile results in elimination of the planar front zones at the treated surface, but this benefit was offset by a coarser microstructure.

Hardness and corrosion protection enhancement behaviour of surgical implant surfaces treated with ceramic thin films

Covalent thin films like TiN and other hard coatings are widely used for tribological and corrosion protection of surfaces. The use of tools covered in thin films in mechanical and chemical industries have increased strongly in the past few years. However, this surface treatment is not commercially applied to surgical implants such as a femoral prosthesis, which is submitted to strong wear and corrosion attack. Ti–6Al–4V ELI alloy together with stainless steel are still the main materials used for medical applications because of their corrosion resistance and biocompatibility. To improve the poor surface hardness and wear resistance of these implants, titanium nitride and (Ti–6Al–4V)N thin films were deposited on the mobile surface. To obtain a good coating–surface adhesion, the protective films were deposited using magnetron sputtering equipment and all samples were cleaned by means of plasma etching in an argon–nitrogen atmosphere. The layers produced have been characterised in terms of phase formation by X-ray diffraction, the composition and depth profile were studied by means of Rutherford backscattering, X-ray photon spectroscopy and energy dispersive spectroscopy (EDS), the hardness was checked using a nano-hardness tester and corrosion protection enhancement was tested using cyclic voltammetry equipment.

Modification of bearing steel surface by nitrogen plasma source ion implantation for corrosion protection

Abstract Nitrogen of doses of 5×10 16 , 1×10 17 and 5×10 17 ions cm −2 was implanted into bearing steel (52100) samples for surface corrosion protection. The implantation was performed by using nitrogen plasma source ion implantation (PSII). The nitrogen distribution and nitride identification were determined by Auger electron spectroscopy and glancing angle X-ray diffraction (XRD), respectively. The corrosion resistance was monitored by using a linear polarization test. XRD measurements confirmed that a thin layer of multiphase iron nitrides was formed on top of the samples after the PSII treatment. The treated bearing steel samples showed a significantly improved corrosion resistance compared with the untreated samples.

Manufacture of thick-walled pressure vessels in particular consideration of advanced welding processes and measures for quality assurance

The use of most advanced welding processes for the manufacture of thick-walled pressure vessels is demonstrated by reference to nuclear component production. A detailed description is given of sub-arc narrow-gap welding and TIG welding as typical joint-welding processes. Surface corrosion protection is provided by weld cladding using corrosion-resistant 18 8 steels or nickel-based alloys. The sub-arc strip process has given excellent results when used for large-area cladding; a most interesting development is the electroslag weld-cladding method. The sub-arc fine-wire process is available for hollow bodies, preferentially with a small diameter. The welding processes referred to above would be incomplete if there were no reference to the special measures taken for satisfying even extremely stringent quality requirements. Quality planning, quality inspection, and quality documentation are combined to form a comprehensive quality assurance programme for ensuring high-quality production as well as the availability of complete quality records without any gaps.