Search results

This study aims to investigate the effect of post heat treatment on mechanical properties of NiCrBSi coatings, which were applied on 316L stainless steel using high-velocity oxygen-fuel (HVOF) and flame spray techniques.

The properties of coatings were investigated by metallographic characterizations as well as wear, micro-hardness and adhesion tests.

The micro-hardness results showed that the coatings considerably increased the sub-layer hardness. In addition, regarding the wear test results, it can be seen that heat treatment increased wear resistance of the coatings. These thermal sprayed coatings are usually re-melted by post heat treatment, leading to improvement in tribological properties. The results obtained revealed that re-melting procedure improved the metallurgical bonding in the substrate\coating interface.

Microstructure defects resulting from thermal spraying such as pores and unmelted particles can be eliminated by post heat treatment. This process can considerably improve the corrosion and wear resistances of the thermal sprayed coatings.

This paper aims to achieve an anti-corrosive coating via uniform dispersion of nanoclay particles (montmorillonite) and polypyrrole (PPy) as a conductive polymer as well as their effects on the anti-corrosion features in the presence of the eco-friendly ionic liquids (ILs).

In this research, PPy with different forms of nanoclay were used. Moreover, ILs additive is used to enhance the better dispersion process of clay and PPy nanoparticles in the resin.

As a result, the IL additive in the formulation of nano-composite coatings greatly improves the dispersion process of clay and PPy nanoparticles in the resin. Due to its high compatibility with polyurethane resin and clay and PPy nanoparticles, this additive contains a high dispersing power to disperse the investigated nanoparticles in the resin matrix.

High polarity of ILs as well as abilities to dissolve both mineral and organic materials, they can provide the better chemical processes compared to common solvents.

IL abilities have not been discovered to a large extent such as catalysts and detectors.

ILs have been emerging as promising green solvents to replace conventional solvents in recent years. They possess unique properties such as nonvolatility, low toxicity, ease of handling, nonflammability and high ionic conductivity. Thus, they have received much attention as green media for various chemistry processes.

The simultaneous existence of clay, PPy and IL additive in the nano-composite coating formulation is responsible for the high corrosion resistance of the coating.

The purpose of this work was to study the effect of different wood surface preparations on the wetting and adhesion of coating.

In this research, six different chemical preparations to evaluate the photostability and properties of wood coating. Also, the effect of the same wood treatments on the properties of the coating, i.e. wetting, adhesion and the permeability of two types of coatings, was investigated.

As a result, benzoyl chloride and chromic acid were found to be the most effective photostabilizing preparations. Solvent-based polyurethane was more compatible with the prepared wood surfaces compared with water-based alkyd coatings.

Chemical modifications of wood surfaces affected the wetting of various coatings.

Various surface properties could be changed using preparation that affects important coating properties.

Unfortunately, the properties of transparent wood coatings used outdoors disappear through the early years of use, essentially due to the wood substrate’s photodegradation.

Wood is a widespread substrate because of its comfortable handling, availability, proper cost of preparation and its good mechanical strength because of its density. Architects and designers tend to use wood in the construction of green buildings. However, this material is disposed to weathering while using outdoors and it should be solved.

The purpose of this paper is to study the correlation between different topographies and the reaction of Ulva Linza fouling species.

In this research, topographies with a different method, such as hot embossing and hot pulling, were achieved, and biological analyses were done with macroalgae Ulva Linza cells. The effect of topography via local binding geometry (honeycomb size gradients) and Wenzel roughness on the settling of Ulva microorganisms was tested.

As a result, Ulva spores confirmed different reactions to a similar set of tapered microstructures that was in agreement with the results on distinct honeycombs. The local binding geometry and the Wenzel roughness factor “r” were dominant on settling of Ulva Linza spores.

The reaction of an organism at the interface of vehicles’ substrate is powerfully affected by surface topographies.

The best embedment occurred on structures with bigger sizes than Ulva Linza’s spores. The density of settled spores was proportional to Wenzel roughness and the spores favour to attach to “kink sites” positions.

Unfortunately, unpleasant aggregation of marine biofouling on marine vehicles’ surfaces, generate terrific difficulties in the relevant industry.

There was a sharp relationship between Wenzel roughness and settle of Ulva Linza spores. The local binding geometry and the Wenzel roughness factor “r” were dominant on settling of Ulva Linza spores.

The purpose of this study was to evaluate the possibility of using conductive polymers such as polyaniline (PANI) as corrosion inhibitors for metals.

In this study, the effect of the addition of praseodymium (Pr³⁺) cations on the corrosion inhibition performance of PANI for AZ31 magnesium alloy was appraised through electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization tests.

The results of EIS and potentiodynamic polarization tests indicated the improvement of corrosion resistance of AZ31 during different immersion times.

This anti-corrosion ability of PANI/Pr³⁺ composite applies as non-toxic environmentally friendly corrosion inhibitor on the self-healing corrosion protection properties.

The conductive polymers are interested for many industries. The reported data can be used by the formulators working in the R&D departments.

The anti-corrosion ability of PANI/Pr³⁺ composite present a novel and high effective route against metal corrosion besides application of toxic corrosion.

The application of titanium dioxide coating in the field of architectural heritage is a great challenge. Therefore, the main objective of this study is to study the synthesis, characterization and corrosion inhibition performance of Pr³⁺ cations doped PANI nano-fibers as an anti-corrosion additive for AZ31 magnesium alloy in 3.5 Wt.% NaCl solution.

This paper aims to achieve phosphating via optimal features of Mg metal as a suitable base coating, which is considered for other properties such as barrier properties against the passage of several factors.

In this research, in the phosphate bath, immersion time, temperature and the content of sodium nitrite as an accelerator were changed.

As a result, increasing the immersion time of AZ31 Mg alloy samples in the phosphating bath as well as increasing the ratio of sodium dodecyl sulfate (SDS) concentration to sodium nitrite concentration in the phosphating bath formulation increase the mass of phosphating formed per unit area of the Mg alloy. The results of the scanning electron microscope test showed phosphating is not completely formed in short immersion times, which is a thin and uneven layer.

Mg and its alloys are sensitive to galvanic corrosion, which would lead to generating several holes in the metal. As such, it causes a decrease in mechanical stability as well as an unfavorable appearance.

Mg is used in several industries such as automobile and computer parts, mobile phones, astronaut compounds, sports goods and home appliances.

Nevertheless, Mg has high chemical reactivity, so an oxide-hydroxide layer is formed on its surface, which has a harmful effect on the adhesion and uniformity of the coating applied on Mg.

By increasing the ratio of SDS concentration to sodium nitrite concentration in the phosphating bath, the corrosion resistance of the phosphating increases.

The purpose of this study is to evaluate the possibility of using titanium dioxide coating in the field of architectural heritage.

In this research, a titanium dioxide coating was prepared and then applied to the travertine stone surfaces. The nature of the coating was determined through various observations and analyses. Moreover, the effect of photocatalytic self-cleaning was evaluated using an organic dye (Rhodamine B).

The results of XRD, DLS and SEM confirmed the formation of small anatase crystals. The hydrophilic behavior on the surface was observed by coatings based on titanium dioxide.

The self-cleaning ability of titanium dioxide is due to the synergistic effect of its optical inductive property, which is activated with sunlight.

The self-cleaning coatings are interested for many industries. The reported data can be used by the formulators working in the research and development departments.

Self-cleaning systems are considered as smart coatings. Therefore, the developing of its knowledge can help to extend its usage to different applications.

The application of titanium dioxide coating in the field of architectural heritage is a great challenge. Therefore, in this research, a titanium dioxide coating was prepared by sol-gel method and then applied on travertine surfaces and its properties were studied.

Post-partum depression (PPD) is a mood disorder that affects 20-40 per cent of women in their post-delivery period worldwide. The purpose of this paper is to compare dietary intakes of energy, macronutrients, cholesterol, saturated fatty acids (SFAs), mono-unsaturated fatty acids (MUFAs), poly-unsaturated fatty acids (PUFAs), some micronutrients and antioxidants in PPD patients with healthy controls.

This case-control study was conducted on 163 women in postpartum period (81 PPD and 82 non-PPD) using Edinburgh questionnaire for the diagnosis of PPD. Dietary nutrients intake was assessed using 147-item semi-quantitative food frequency questionnaire (FFQ). Portion sizes of food items were converted to grams per day. Logistic regression models were used to estimate the association between tertiles of dietary intakes with the odds ratio (OR) of PPD.

According to the fully adjusted model, highest tertile compared to lowest tertile dietary intake of SFAs [OR = 0.01; 95 per cent confidence interval (CI) = 0.00, 0.01, p = 0.001], MUFAs (OR = 0.01; 95 per cent CI = 0.00, 0.02, p < 0.001), total fats (OR = 0.01; 95 per cent CI =0.00, 0.01, p < 0.001) and cholesterol (OR = 0.06 ; 95 per cent CI = 0.01, 0.08, p < 0.001), thiamine (OR = 0.01; 95 per cent CI = 0.00, 0.01, p < 0.001), riboflavin (OR = 0.10; 95 per cent CI = 0.02, 0.39, p < 0.001), pyridoxine (OR = 0.03; 95 per cent CI =0.01, 0.32, p < 0.001), folate (OR = 0.01; 95 per cent CI = 0.00, 0.01, p < 0.001), cobalamine (OR = 0.01; 95 per cent CI = 0.00, 0.01, p < 0.001) , selenium (OR = 0.79 ; 95 per cent CI =1.36, 3.32, p < 0.001), iron (OR =0.68; 95 per cent CI = 0.24, 0.94, p < 0.001) and iodine (OR = 0.36; 95 per cent CI =1.10, 1.38, p < 0.001) had a protective effect on the incidence of PPD. Furthermore, higher intake of vitamin A and beta-cryptoxanthin can increase the incidence of PPD (OR =114.29; 95 per cent CI =17.85, 118.12, p < 0.001) and (OR = 4.85; 95 per cent CI = 1.49, 15.69, p = 0.015), respectively.

PPD may have destructive effects on the relationship between mother and infant. Results of previous studies demonstrated nutrients are required for the synthesis of neurotransmitters and have biochemical role in the nervous system.

Due to the extensive industrial applications of stagnation flow problems, the present work aims to investigate the magnetohydrodynamics (MHD) flow and heat transfer of a magnetite nanofluid (here Fe₃O₄–water nanofluid) impinging a flat porous plate under the effects of a non-uniform magnetic field and chemical reaction with variable reaction rate.

Similarity transformations are applied to reduce the governing partial differential equations with boundary conditions into a system of ordinary differential equations over a semi-infinite domain. The modified fourth-order Runge–Kutta method with the shooting technique which is developed for unbounded domains is conducted to give approximate solutions of the problem, which are then verified by results of other researchers, showing very good agreements.

The effects of the volume fraction of nanoparticles, permeability, magnetic field, chemical reaction and Schmidt number on velocity, temperature and concentration fields are examined and graphically illustrated. It was found that fluid velocity and temperature fields are affected strongly by the types of nanoparticles. Moreover, magnetic field and radiation have strong effects on velocity and temperature fields, fluid velocity increases and thickness of the velocity boundary layer decreases as magnetic parameter M increases. The results also showed that the thickness of the concentration boundary layer decreases with an increase in the Schmidt number, as well as an increase in the chemical reaction coefficient.

The thermophysical properties of the magnetite nanofluid (Fe₃O₄–water nanofluid) in different conditions should be checked.

Stagnation flow of viscous fluid is important due to its vast industrial applications, such as the flows over the tips of rockets, aircrafts, submarines and oil ships. Moreover, nanofluid, a liquid containing a dispersion of sub-micronic solid particles (nanoparticles) with typical length of the order of 1-50 nm, showed abnormal convective heat transfer enhancement, which is remarkable.

The major novelty of the present work corresponds to utilization of a magnetite nanofluid (Fe₃O₄–water nanofluid) in a stagnation flow influenced by chemical reaction and magnetic field. It should be noted that in addition to a variable chemical reaction, the permeability is non-uniform, while the imposed magnetic field also varies along the sheet. These, all, make the present work rather original.

The contemporary landscape of supply chains necessitates a comprehensive integration of multiple components encompassing production, distribution and customer engagement. The pursuit of supply chain harmony underscores the significance of pricing strategies within the framework of dual-channel distribution, particularly when confronted with the dynamics of asymmetric demand performance.

This paper delves into a nuanced decision-making challenge anchored in a dual-channel distribution context featuring a retailer and two distinct products. Notably, the retailer’s decision-making process employs the computational framework of dual grey numbers, a robust tool for handling uncertainty.

This study revolves around applying game theory to manufacturers. Each manufacturer presents its aggregated price proposition to the retailer. Subsequently, the retailer identifies the optimal pricing configuration among the manufacturers' aggregate prices while adhering to constraints such as spatial classification and inventory costs. This article’s contribution extends to delineating the retailer’s capacity to discern the influence of product market potential and the aggregate product cost on the overall demand.

The model’s innovation lies in its harmonious fusion of spatial classification, pricing strategies and inventory control. Notably, this novel integration provides a platform for unraveling the intricate interplay between non-symmetric market potential, production costs and cross-sensitivity. The investigation is underscored by the utilization of the double interval grey numbers, a powerful computational approach that accommodates the inherent uncertainty pervasive in the domain. This study fills a gap in the existing literature by offering an integrated framework unifying spatial allocation, pricing decisions and inventory optimization.