Cavitation erosion resistance of steels is important in many applications. The investigation of such resistance, under different conditions, should be very useful. Cavitation erosion tests were carried out on carbon steel AISI-1045 using an ultrasonic induced cavitation facility. Cavitation erosion pits and their effect on the localized corrosion were investigated in detail in three different corrosive media: distilled water, tap water, and 3% NaCl water. The results of the investigation using SEM indicated the formation of three types of pits on cavitating specimen surfaces: corrosion pits, erosion pits, and erosion-corrosion pits. The corrosion pits have different shapes, however, the lamellar structure is the dominant structure, and has a large size of about 100 μm. The erosion pits that were formed by the cavitation microjet impacts have sizes of a few micrometers. The erosion-corrosion pits were similar to the corrosion pits, except the erosion pits formed on the corrosion pit surface due to dissolution. The eroded surface removal was the largest in the case of saline water.

This research article investigated the notch sensitivity of two different glass fibre architectures, namely short and 2D plain-woven glass fibres reinforced with unsaturated polyester and epoxy matrix composites fabricated by the hand lay-up technique. This was carried out through open hole tension tests at different ratios of the specimen hole diameter to the specimen with three different values (0.1, 0.2, 0.5) compared to the unnotched specimen. The notch sensitivity of these composites was evaluated using the residual tensile strength by the application of Whitney–Nuismer Mathematical Model. The results showed that by using polyester matrix, the notch sensitivity of composites reinforced with plain-woven glass fibre is higher than that of short glass fibre at different D/W ratios. On the other hand, on testing epoxy matrixes, the notch sensitivity of composites reinforced with plain-woven glass fibre is lower than that of short glass fibre at different D/W ratios.

The objective of this work is to compare the mechanical properties including tensile, bending and impact properties between different glass fiber architecture reinforced polyester composites which are fabricated by a hand lay-up technique. The effects of stacking sequences of glass fibers consists of five layers which mainly are plain woven, short fiber, and sandwich layer glass composites on the mechanical properties of composites have been studied. The results showed that the tensile and bending properties of all different composite laminates are significantly higher compared to the neat resin. The plain woven glass reinforced polyester composites showed the highest values compared with other composite laminates. As the glass fiber mats a core are tightly packed and absorbs the impact stresses and distributes them evenly in the composites sandwich layer, the glass composites showed the highest value of impact strength compared with other composite laminates. Moreover, from SEM investigations, in these composites, there is an inverse relationship between the amount of delamination and the amount of hackles, and as the hackles increase the mechanical properties including tensile and bending of these composites are enhanced.

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Purpose The ability to produce a uniform composition, high corrosion resistance with a hard coating layer during the electroless coating techniques are mainly based on the plating bath composition. The complexing agent is one of the most important components that control the coating layer properties. This paper aims to investigate the effect of the glycine as a complex agent on the surface and corrosion properties of Ni-P and Ni-P/Al2O3 electroless coating. Design/methodology/approach In this study, the effect of glycine as a complexing agent on the final surface and corrosion properties of the Ni-P and Ni-P/Al2O3 coatings has been investigated. The surface morphology and composition of the coated samples were investigated by scanning electron microscope (SEM) imaging and energy dispersive x-ray spectroscopy (EDS) analysis. Linear polarization scan and electrochemical impedance spectroscopy techniques were used to investigate the corrosion properties of the coating layer. Findings The results clarify that, glycine has a remarkable effect on the porosity content of Ni-P and Ni-P/Al2O3. It was found that increasing of glycine concentration results in higher porosity content in the coating layers. Also, the porosity in the coating layers minimizes the protectability of the coating against corrosion. The results also show that adding nano-alumina (Al2O3) to the coating path has improved the corrosion properties by decreasing the porosity in the coating layer. The scanning electron microscope (SEM) images showed that the concentration of glycine affects the content and distribution of alumina nanoparticles embedded in the coating layer. Also, it was observed that using a high concentration of glycine (0.4 M glycine), the alumina tends to agglomerate and the final alumina content in the coating was decreased. Originality/value The present study reveals that the quality of the final coating plays a major role in the corrosion performance of the steel substrate. The coating quality can by improve remarkably by optimization of the complexing agent used in the plating bath, to minimize the porosity involve in the coating layer.

Electroless Nickel-Phosphorus coatings have had a lot of interest in various industries due to outstanding characteristics. Some of the highlighted characteristics of electroless Ni-P coatings are superior corrosion and wear resistance. But the effectiveness of electroless Ni-P coating in resisting cavitation damage is not studied so well and is not so clear. In the present investigation, electroless Ni-P coatings were prepared at various conditions including the type of bath, heat treatment temperature and plating solutions composition. The properties of electroless Ni-P coatings were characterized using X-ray diffraction technique (XRD), energy dispersive X-ray (EDX) optical microscope, and microhardness tester. The cavitation erosion tests were carried out to study the effect bath type, heat treatment temperature and plating solutions composition on the deposit coatings.The XRD results indicate that the as-deposit had crystalline structure for alkaline bath and amorphous structure for acid bath. Heat treatment of the coatings produced mixture of polycrystalline phases. The thickness of deposit films depend on the bath type and concentration and were the least for alkaline baths. Maximum hardness of heat treated samples was found to depend on the solution composition and occurs at temperature 300 °C and 400°C.The highest erosion resistance of the coatings was observed for the heat treated deposits at temperature of 650 °C, and comes to the fore the coatings formed in alkaline baths followed by that formed in acid baths. The best erosion resistance for deposits formed in alkaline baths is attributed to the small thickness and crystalline structure. The results showed also that the cavitation erosion resistance is independent on surface hardness.

Electroless NiP coatings use in engineering applications due to its ability to alter and improve the surface properties of the steel substrate. The present study investigates the influence of bath composition, which included nickel sulphate, sodium hypophosphite, and glycine on the deposition rate, coating roughness, and final coating microhardness with using of Taguchi techniqe. The results reveal that final coating roughness and hardness can be optimized by controlling bath composition. The achieved minimum average surface roughness (Ra) was 80.7 nm and the highest coating hardness was 1145 HV.

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