Changes In Protective Properties Research Articles

Changes in protective properties of zirconia and silica sol-gel layers over time

The study investigated the effect of aging time on the protective properties of submicron thickness sol-gel coatings. Coatings were based on zirconia and silica modified with fluoroalkyl substituents that were deposited on P265GH steel and were aged for 3 years. The corrosion tests were carried out in sodium chloride solution and liquid caprolactam. The physicochemical properties of the obtained materials were determined using scanning electron microscopy (SEM), Raman spectrometry, and nuclear magnetic resonance (NMR). The roughness and wettability of the tested samples were also measured with a profilometer and tensiometer. The protective properties were determined by electrochemical and immersion tests. The coating containing ZrO2 was more stable over time. In the case of the ‘SiO2 + F’ fluorine-modified coating, polarization resistance increased by about 3 orders of magnitude compared to the uncoated P265GH steel. However, after 3 years, the protective nature of this type of coating had deteriorated, compared to its initial state. Moreover, it seems that the ‘ZrO2’ coating better covered all valleys in the surface, forming a smoother surface, while the ‘SiO2 + F’ coating better reproduced the surface topography, also depositing on the ridged surface and creating a thin continuous film.

Barrier properties of anti-gas military garments, considering exposure to gas organic compounds

The problems of determining the protective properties of barrier materials used for the production of body surface protection products of an isolative type are very actual. These garments are expected to have long-term resistance against permeation of toxic substances. The paper deals with the study of the effect of organic solvent vapours on the changes in protective properties of selected anti-gas protective garments commonly used by the North Atlantic Treaty Organization armed forces. Permeation measurements of selected gases with integral permeameter were performed to verify their barrier properties, surface changes after exposure to selected solvents by using a 3D optical profilometer, permeation measurements for vapours of these solvents with differential permeameter, and experimental simulating the possible influence of barrier properties of garments within permeation of air. It has been shown that in the case of gases, the permeability of the studied materials increases with decreasing kinetic diameter of the penetrant molecule used. In the case of acetonitrile and isooctane vapours, permeability increased with increasing vapour concentration due to interactions between polymeric materials and molecules of organic compounds. The permeation measurements of pure vapours and air/vapour mixtures indicate that the level of interactions between the molecules of the penetrant and the material of the protective garment is not strong enough to degrade the material of the garment in such a way as to allow a greater penetration of the pollutants through it. The results of permeation experiments for gases and organic vapours showed very good barrier properties of studied chemical isolated garments.

Effects of corrosion inhibitors on protective properties of preservative oil film in the course of aging

To this end, we tested the protective properties of mineral oil base stocks with corrosion inhibitors differing in their mechanism of action. The electrical properties of the base stocks had the following parameters: dielectric constant 2.26, conductivity 25 pS/m. The content of inhibitor in the oil base Stock was 5% by weight. The following corrosion inhibitors were used: calcium alkylbenzenesulfonate (Sab ca), isododecenylsuccinic acid (KAP-25), alkenylsuccinimide of urea (SIM), alkylbenzenesulfonate of urea (BMPA), pentaerythritol ester of fatty acids (EPZhK), oxidized petrolatum (OP), and alkeny!succinic anhydride (AYaA). The test results given in Table 1 are expressed in terms of the protective effect and the relative change in protective properties of the oil. The protective effect is defined as the ratio of the corrosion rate of metal protected with the uninhibited oil base stock to the corrosion rate of metal protected by the base stock with the corrosion inhibitor, under identical conditions [3]. The relative change in protective properties is defined as the ratio of the specific weight losses of metal when protected by the oxidized on unoxidized oil film [i]. According to modern concepts of the mechanism of action of oil-soluble corrosion inhibitors [4], the inhibitors in this group can be classified as follows: Sab Ca and KAP-25 are chemisorption type inhibitors with a donor action; SIM and BMPA are chemisorption type inhibitors with an acceptor action; EPZhK, OP, and AYaA are adsorption type inhibitors with a shielding action. It should be noted that for all of the chemisorption type inhibitors (with the exception of the SIM), the protective properties in the gas/air corrosive medium proved to be considerably better than in the aqueous electrolyte solution. For the adsorption-type corrosion inhibitors, the protection in the gas/air corrosive medium was approximately the same as in the electrolyte solution. The studies of stability of protective properties of these corrosion inhibitors showed the following: For the shielding inhibitors, the protective properties did not change or even improved slightly as a result of oxidation of the oil in a thin film on the metal surface (steel i0); the corrosion inhibitors with a donor or acceptor action, in a number of cases dropped in protective efficiency under analogous conditions. From these results, we canconclude tentatively that the changes in protective properties of films of preservative and operational/preservative oils in the course of aging can be

Stability of protective properties of preservative oils

This article evaluates the stability of the protective properties of preservative oils when they are oxidized in the bulk and in a thin layer. Proposes a method based on a quantitative evaluation of the changes in protective properties of the oils after artificial oxidation in the bulk and in a thin layer on a metal surface. Finds that the proposed method makes it possible to establish the character of changes in protective properties of preservative oils during storage and application, and to differentiate oils with respect to this index over a broad range of protective levels.