Search

This article presents a concise review of different types of inhibitors for corrosion protection on metal surfaces. Corrosion inhibitors can be of different types, which include organic, inorganic and hybrid (organic/inorganic) materials. They are also classified as cathodic, anodic and/or mixed-type inhibitors, which are based on the active inhibitor molecules that retard the corrosion process. Silicate, nitrites, molybdates, phosphates, zinc salt and cerium salt are widely used as inorganic inhibitors. Many organic compounds have been widely utilized as inhibitors. Corrosion protection will be obtained by various mechanisms such as physisorption, chemisorption, barrier protection, thin-film formation and electrochemical processes. The type of inhibitors, inhibition mechanism and the evaluation methods have been explained in detail.

In this work, the corrosion inhibition performance of 1,2,3 – Benzotriazole (BTA) as an organic inhibitor for cold rolled mild steel in an acidic medium was investigated. For this, different loading ratios of BTA were utilized and their efficiency as corrosive inhibitor either within the coating film or within the electrolyte was discussed. The first set of the samples was fabricated by the incorporation of 0.1 wt.%, 0.5 wt.%, and 1.0 wt.% BTA within the acrylic polymer host matrix. The influence of BTA to the structural, optical, and adhesion properties of the acrylic coating films was examined. The obtained results revealed no significant changes resulted from the addition of different concentrations of BTA. The other set of the samples was developed by dissolving different concentration of BTA specifically, 100 ppm, 500 ppm, and 1000 ppm within the acidic electrolyte. All tested substrates were coated with acrylic based coating systems in the presence of polyisocyanate (NCO) as a curing agent. 0.5 M H2SO4 was used as the corrosive electrolyte and the corrosion protection performance of the two sets of the samples was investigated via electrochemical impedance spectroscopy (EIS). The obtained results confirmed the way of introduction influenced the performance of the BTA as a corrosion inhibitor. The best corrosion protection and the intact behavior was observed by adding 0.1 wt.% of BTA within the acrylic coating film even after 30 days of exposure of coated substrate to H2SO4 solution.

Silicone-modified epoxy polymeric matrix was successfully fabricated and reinforced with 1–2 wt% SiO2, TiO2, and TiSiO4 nanoparticles. Fourier-transform infrared spectroscopy, contact angle measurements, differential scanning calorimetry, and field-emission scanning electron microscopy together with energy-dispersive X-ray spectroscopy were employed to investigate different characteristics of the prepared coatings. To simulate operating conditions, all samples were characterized via electrochemical impedance spectroscopy (EIS) after being subjected to different conditions. Corrosion under static conditions, in which the samples were exposed to a static electrolyte without further change in other parameters, was investigated. Furthermore, to study the effects of ultraviolet (UV) radiation in accelerating the degradation of the coatings, samples were characterized after being subjected to UV while immersed statically in the electrolyte. Additionally, the corrosion protection performance was investigated after subjecting the coated substrates to dynamic conditions involving continuous movement of the sample in the electrolyte, simulating continuous wear of the coated surfaces. Compared with the static condition, the EIS results revealed the vital role of the silicone resin and nanoparticles in improving the stability of the coating film against corrosion degradation in the presence of UV radiation, while poor performance in dynamic condition was recorded for all the coating systems.

Hybrid polymeric based nanocomposite coating systems (NCs) were fabricated by solution intercalation method with the use of epoxy (E) and polydimethylsiloxane (PDMS) as the host hybrid polymeric matrix and different weight ratio of SiO2 nanoparticles, ranging from 2 wt. % to 8 wt. %, as the reinforcing agents. The effects of introducing PDMS as a modifier to epoxy resin, as well as, the influence of embedding SiO2 nanoparticles within the developed matrix were evaluated via utilizing X-ray diffraction (XRD), contact angle measurements (CA), field emission scanning electron microscope (FESEM), and electrochemical impedance spectroscopy (EIS). XRD and FESEM results revealed the good dispersion of the nanoparticles within the polymeric matrix and confirmed the efficiency of the solution intercalation method. CA findings confirmed the achievement of hydrophobic surface after modifying epoxy resin with PDMS with CA value at 96° for epoxy-PDMS coating system (ES 0). Also CA results indicated the ability of SiO2 nanoparticles to participate in developing more hydrophobic surface as CA value up to 132° was achieved with utilizing 6 wt% SiO2 loading ratio. The results obtained from EIS studies revealed that the coating system with 2 wt% had the best anticorrosion performance and have demonstrated an intact behavior over all the immersion period without any sign of coating damage or degradation.

Polymer-based nanocomposite coatings (PBNCs) are hybrid coating systems that consist of two different phases, namely, the matrix (i.e., polymeric resins) and the reinforcing agents in the nanosized domain (i.e., inorganic nanoparticles). PBNCs have numerous potential applications in the automotive, construction, energy, consumer electronic goods, military, and medical applications. It is an excellent choice as a comprehensive coating system to ensure the stability and the corrosion protection of the coated material along with other functional properties, such as the hydrophobicity, self-cleaning ability, self-healing with superior adhesion, transparency, ultraviolet (UV) stability, and low infrared emissivity. PBNC coating systems have been used and investigated during the last few years. However, this chapter will obtain detailed information about the recent attempts that aimed to develop polymer-based coating systems and further discuss the influence of embedding different types, size and loading ratio of inorganic nanoparticles within the different types of polymeric host matrices. As the polymeric matrices usually characterized with weak barrier performance, hydrophilic surface, low thermal and UV stability, the chemical resistance, the high affinity between water and polar groups of polymers, which in turns, limit the applications of these materials. Therefore second phase in the form of nanosized inorganic particles will be needed to overcome the polymeric materials short comes. The combination of the organic and inorganic functionalities as well as the distinctive properties of the materials in the nanodomain play the vital role in developing a unique mixture of desired properties without sacrificing in any of the starting materials features.

The influence of SiO2 nanoparticles on hydrophobicity and the corrosion protection capabilities of hybrid acrylic-silicone polymeric matrix have been investigated. Contact angle measurements (CA), atomic force microscopy (AFM), field emission scanning electron microscopy (FE-SEM), and energy dispersive X-ray spectroscopy (EDX) were used to study the hydrophobicity, morphology, and topography of the coatings. In addition, electrochemical impedance spectroscopy (EIS) and salt spray techniques were employed to evaluate the corrosion protection performance. A coating with 3 wt.% SiO2, AS 3, demonstrates significant improvement in corrosion resistance with the highest measured CA of 97.3°. Morphology and topography studies clarify the influence of nano-sized SiO2 fillers on the surface topography and demonstrated the uniform and good distribution of the embedded SiO2 nanoparticles within the polymeric matrix.

The influence of using two types of carrier agent namely, water and solvent, on the overall performance of epoxy resin has been investigated. Furthermore, four different loading rates of copper pigments (Cu) have been successfully embedded into two developed polymeric matrices and the changes occurred in the structure, thermal, fouling ability, morphology, and the anticorrosion performance have been studied. Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), field immersion test, scanning electron microscope (SEM), and electrochemical impedance spectroscopy (EIS) were used to evaluate the formulated coating systems. The results revealed that, the incorporation of Cu pigments did not significantly affect the efficiency of the room temperature curing process and further led to enhancement on the thermal stability of both developed epoxy resins. However, utilizing Cu pigments with solvent based epoxy (SB) showed better antifouling and anticorrosion properties compered to Cu composites prepared with water based epoxy resin (WB). The electrochemical behavior up to 30 days of immersion in 3.5% NaCl solution confirmed that the SB resin loaded with Cu pigments at 10% PVC, SB 10, demonstrated excellent barrier and anticorrosion properties. Neat WB coating (WB 0) was found to have the best performance among all WB coating systems.

In this study, ZnO nanoparticles ranging from 1 to 8% (w/w) were introduced into a hybrid acrylic-silicone polymeric matrix to achieve nanocomposite coating systems with remarkable anti-corrosion and hydrophobic characteristics. The chemical structure of the developed hybrid polymeric matrix was investigated using Fourier transform infrared spectroscopy, whereas the morphology and wettability of the developed surfaces were determined using field emission scanning electron microscopy and contact angle measurements (CA), respectively. Furthermore, the anti-corrosion performance and the barrier properties over 60 days of exposure to a 3.5% NaCl solution were studied by electrochemical impedance spectroscopy. All the obtained results revealed that the presence of ZnO nanoparticles significantly influences the performance of the acrylic-silicone polymeric matrix. A coating system with 3% wt ZnO nanoparticles demonstrated the most pronounced anti-corrosion properties and also achieved the highest CA, with a value of 95.6°.

Epoxy-polydimethylsiloxane (PDMS) nanocomposite coatings loaded with different concentrations (ranged from 2 to 8% (w/w)) of ZnO nanoparticles have been successfully achieved by using the solution intercalation method. In this study, it has been aimed to investigate corrosion protection performance and hydrophobic properties of epoxy/PDMS nanocomposites (NC). Fourier transform infrared (FTIR) spectroscopy was utilized in order to study the chemical structure of the developed coatings. The coating surface wettability was studied by contact angle measurements and the dispersion of ZnO nanoparticles was examined via field emission scanning electron microscope (FESEM). The effects of ZnO nanoparticles on the corrosion resistance and the barrier performance were investigated by electrochemical impedance spectroscopy (EIS). Thermal properties were evaluated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) From the FTIR spectra it was observed that the incorporation of nano ZnO particles has demonstrated peak shift and change in intensity. The incorporation of nano ZnO particles within the hybrid polymeric matrix had improved the hydrophobicity in terms of contact angle which reached maximum as 128° for NC6 system. NC2 coating had shown higher coating resistance more than 109 Ω even after 30 days of exposure in electrolyte medium. The results obtained from TGA and DSC studies demonstrated that introducing PDMS to epoxy resin increased Tg whereas the incorporation of ZnO nanoparticles in the nanocomposite coatings showed reduction in degradation temperature, cross-linking density of the composite by lowering Tg.

Hybrid materials are inimitable conjugates of organic/inorganic structures having synergetic behaviour and extraordinary properties. Therefore, hybrid chitosan/silica composite was synthesized by using sodium tripolyphosphate via ionotropic gelation technique. The obtained intercalation of hybrid chitosan/silica composite was characterized using Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD) analysis. The surface morphology of the composite was studied through field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). The EDX analysis was performed to find the wt.% of the present elements in the composite that showed the increment of O element up to 47.50 wt. % and the presence of Si (27.61 wt. %) revealed that the silica is present within the chitosan matrix, which demonstrates successful hybridization of chitosan/silica. Furthermore, the obtained hybrid chitosan/silica was incorporated within the epoxy matrix and electrochemical studies such as electrochemical impedance spectroscopy (EIS) was employed for 60 days. The experimental results revealed that the presence of hybrid chitosan/silica composite up to 0.8 wt. % resulted in a profound outcome as a considerable active reinforcing agent for corrosion prevention application with the highest coating resistance, (1.97 ± 0.01) × 1011 Ω and lowest breakpoint frequency, 51 × 10-3 Hz after 60 days.

In this study, different loading ratios of epoxy resin (E) and epoxidized soybean oil (ESO) were introduced into acrylic–silicone polymeric blend with the presence of polyisocyanate (NCO) as the curing agent. The developed coating systems were applied on pretreated cold rolled mild steel substrates and the overall performances were investigated by means of Fourier transform infrared (FTIR) spectroscopy, contact angle measurements (CA), UV–vis analysis, thermogravimetric analysis (TGA), electrochemical impedance spectroscopy (EIS) and salt spray test. Moreover, the physico-mechanical properties of all developed coating systems were investigated. The obtained results revealed the ability of the combination of E and ESO at a certain concentration specifically, 9:1, to enhance the overall performance of the polymeric matrix as optimum curing level, better wettability, good physical-mechanical characteristics, thermal stability and significantly enhanced corrosion resistance were observed. The results also demonstrated the ability of the fabricated single-layer coating system to serve as a primer, topcoat or single coating system that has promising potential to be applied for decorative, self-cleaning, thermal insulation and corrosion protection purposes.

Objective The purpose of this study is to evaluate the efficacy of fibrin glue and fascia lata graft as a substitute for dural repair in postoperative cerebrospinal fluid (CSF) leak after cranial surgery. Background Postoperative CSF leakage is a common complication after many cranial and spinal operations. Several methods are used for repair of dural tears to stop CSF leak; one of these methods is to use fibrin glue with autologous graft - for example, fascia lata - for repair. Materials and methods A total of 12 cases with postoperative CSF leak after cranial surgery were observed and managed in the period from June 2010 to December 2012. In all, four cases were meningiomas and eight cases were gliomas. Male-to-female ratio was 5 : 7 and mean age was 56.8 years. All cases underwent secondary surgery to manage the CSF leak by fascia lata graft and fibrin glue. Mean duration of follow-up was 9.8 months (range 6-20 months). Computed tomography brain with and without contrast was performed to determine the presence of CSF leaks between 2 weeks and 3 months after surgery. Results No CSF fistula was found in all patients. No adverse effects or complications such as wound infection or neurological impairment were encountered postoperatively. Follow-up computed tomography brain revealed no evidence of CSF leakage. Conclusion The use of fascia lata graft and fibrin glue is a useful and effective method in controlling CSF leakage after cranial surgery.

Objective The aim of the present study was to compare the clinical outcome of discectomy alone with discectomy and fusion in the treatment of recurrent lumbar disc herniation. Background Lumbar disc herniation is one of the most common spinal conditions and causes widespread medical problems. The management of recurrent disc herniation remains somewhat controversial. Surgical treatment for recurrent disc herniation can be broadly categorized as revision discectomy alone or revision discectomy and fusion. Patients and methods Fifty patients (35 M, 15 F) with an average age of 45.9 years (range: 31-60 years) were retrospectively and prospectively evaluated. All patients underwent discectomy ( n = 22) or discectomy and fusion (transpedicular screws with or without interbody fusion) at Menoufia University Hospitals, from January 2011 to April 2014 (minimum 12-month follow-up). The clinical and radiographic results were compared between the two groups. Clinical outcome was assessed using the visual analogue scale (VAS) and the Oswestry disability index. Results In comparison with the discectomy group, the discectomy and fusion had significantly lesser VAS (leg pain), VAS (back pain), and lesser Oswestry disability index during the follow-up period postoperatively. Complications included cases of seven small dural tear in the discectomy group. There were four cases of dural tear and two cases of superficial wound infection in the discectomy and fusion group. One case of hardware failure was observed in the discectomy and fusion group. Conclusion In cases of recurrent lumbar disc herniation, the clinical outcome is better when the patients were operated by using discectomy and fusion rather than using discectomy alone.