Coatings For Protection Of Steel Research Articles

Effect of the Al/Si ratio on intumescent Na-based geopolymer

This research investigates the fire resistance properties of alkali activated Na-based geopolymers (GP), used as steel protective coatings. The effect of different Al/Si molar ratios (0–0.54) is evaluated fire test. When coated on a steel plate, GP having the smaller Al/Si ratio exhibits an intumescent behavior with the highest expansion. When Al/Si = 0, the temperature at the backside of the steel plate is 313 °C which is decreased by 347 °C compared to an uncoated steel plate (660 °C). After fire testing, the GP physico-chemical properties are characterized with optical microscopy, Electron probe micro-analysis, dynamic mechanical analysis. According to stiffness test results, when the temperature approaches 100 °C, the GP with a given Al/Si ratio (different from zero) softens and expands (intumescence). The greater the Al/Si ratio in the GP, the more rigid the structure; this phenomenon limits expansion, and hence, lowers the fire protection.

Nanocontainers for Self‐Healing Coatings

This progress report covers recent achievements in the development of nanocontainers for self‐healing corrosion protection coatings. The functionality and design of Layer‐by‐Layer‐assembled, polymer, and inorganic nanocontainers are demonstrated in the coatings for protection of steel and aluminium alloys. The release of the corrosion inhibitors from nanocontainers occurs only when triggered by local pH changes or other internal or external stimuli, which prevents leakage of the corrosion inhibitor out of the coating and increases coating durability. This leads to the self‐healing ability of the coating and terminates corrosion propagation.

Evaluation of corrosion resistance of coated steel strips embedded in mortar under chloride exposure

Purpose – The purpose of this paper was mainly to select one of the three types of coatings for protection of steel used as reinforcement in composite pipes (thin steel shell covered by cement-mortar) subjected to chloride exposure. To achieve this target, an attempt was made to develop a simple methodology for evaluating the performance of corrosion protection measures in terms of chloride threshold level (CTL) and corrosion initiation time (TI). Design/methodology/approach – Bare, epoxy, red oxide and zinc primer-coated steel strips were embedded in cement mortar with sand/cement and water/cement ratios of 2 and 0.5 (by mass), respectively, to prepare the specimens which were exposed to chloride solution having a high concentration of 10 per cent NaCl. For determining the amounts of the water-soluble chloride diffused inside the specimens, powdered samples of mortar were collected from two different depths from the exposed surface of specimens on completion of each of the four different exposure times. The corrosion current densities were determined at two different stages. A step-by-step procedure for calculating CTL and TI using the measured chloride contents and corrosion current densities was established with the help of relevant information available in the literature. Findings – Based on the comparison of the values of CTL and TI calculated for bare steel and steel with all three types of coatings, utilizing the experimental data and the proposed calculation procedure, the epoxy-coated steel was found to have the best performance. Originality/value – This research has resulted into development of a simple methodology for evaluation of the performance of protective measures against corrosion of steel embedded in mortar or concrete exposed to chloride-bearing environment.

Experimental Study on Testing Ni-Containing Stainless Steel Protective Coatings by Pulsed Laser Scratching

In the experiment, we use pulsed laser to conduct discrete scratching on Ni-containing stainless steel protective coatings to test residual stress situation after the matrix is scratched; then to analyze the the impact of the impact stress wave on coating - substrate bonding strength according to the test results, finally to infer the laser power density range within which it occurs coating failure. The study shows that: after laser discrete scratching, the residual stress of the center of the laser-loaded point on matrix surface gradually reduces when the pulsed laser power density increases. The matrix produces a corresponding residual compressive stress under the laser power density reaches a certain value. The actual failure threshold values are 12.006 GW/cm2, 11.829GW/cm2 and 12.193GW/cm2 measured by the three-dimensional topography instrument testing the discrete scratch point of three groups of samples and verified by using a microscope

Using gas-thermal coatings for high-temperature protection of steel

Using gas-thermal coatings for high-temperature protection of steel

Coatings for corrosion protection of steel used in reinforced concrete

Coatings for corrosion protection of steel used in reinforced concrete

Phthalocyanine and Polyphthalocyanine Coatings for Corrosion Protection of Metals

ABSTRACTThe effectiveness of phthalocyanines and polyphthalocyanines as corrosion inhibiting coatings for protection of steel have been studied. The metallo-phthalocyanines studied included phthalocyanine tetracarboxylates of Fe(III), Co(II), VO(IV), Cr(III), Si(IV) and Zn(II). Polymeric phthalocyanine coatings based on Fe(III) polyphthalocyanines gave the highest inhibitor efficiency of 82%, as confirmed by AC impedance analysis. The polymerization was achieved by simple dip coating followed by heat treatment of the coated surface at 450°C in an inert atmosphere. The resulting coating is adherent and electrically conducting when appropriately doped. Our recent findings indicate that the inhibition efficiencies can be further improved by introducing a long alkyl chain into the phthalocyanine molecule.

Ion plated aluminium coatings for the corrosion protection of steel

Ion plating or ion vapour deposition has become a widely accepted process for the application of dense, uniform and very adherent aluminium coatings for corrosion protection. Because of its performance advantages, this process is expected to replace cadmium electroplating in the near future. Recently, General Engineering Radcliffe Ltd took out a UK licence from McDonnell Aircraft Corporation to manufacture commercial machines called ‘Ivadizer’ for applying aluminium coatings for corrosion protection. The purpose of this paper is to present the physical and technical aspects of the ion plating process and its unique characteristics in corrosion prevention.