Effects of seawater corrosion environment on the impact behavior of multi-walled carbon nanotube and SiO2 reinforced basalt/epoxy hybrid nanocomposites

In this study, the impact behaviors of nano silica (SiO2 nanoparticles), MWCNTs (multi-walled carbon nanotube), and SiO2+MWCNTs (nano silica vs multi-walled carbon nanotube hybrid) nanoparticle additives in basalt fiber reinforced composites exposed to seawater corrosion were investigated. The Mediterranean was chosen as the corrosive sea water due to its high salinity. Basalt fiber reinforced composites immersed in seawater have quick mass absorption during the first 30 days. However, it can also vary between the first 28 and 40 days depending on the structure of the composite and environmental conditions. Immersion times were determined as 0, 10, 20, and 40 days. Tensile and low velocity impact tests were performed to evaluate the mechanical performance after seawater corrosion. Low velocity impact tests were carried out at 10 and 20 J energy levels. The aim of this study was to examine the effects of corrosion caused by quick mass absorption on the tensile and impact behaviors of basalt fiber reinforced composites. And also to investigate the contribution of SiO2 and MWCNT nanoparticle additives to the mass absorption mechanism and mechanical performance of basalt fiber reinforced composites. SiO2 and MWCNT nanoparticle additives increased the tensile and impact strength of basalt fiber reinforced composites. However, the tensile and impact behaviors of nanoparticle filled and nanoparticles unfilled basalt fiber reinforced composites were adversely affected by the seawater corrosion environment. Due to the geometric structure of SiO2 nanoparticles, the best mechanical performance was observed in SiO2 filled basalt fiber reinforced composites.

ANALISIS PENGENDALIAN KOROSI PADA PERMUKAAN BASAH KAPAL-KAPAL BAJA DENGAN MENGGUNAKAN ZINK ANODA

Zink anodes are very importantfor reducing the corrosion rate on underwater surface area of hull plates. Zink anodes are affixed to parts of the vessel that are prone to seawater corrosion. This study aims to find out how much influence the installed current has on the corrosion rate by analyzing the data on the use of zink anodes in the field and the data on the use of zink anodes as a result of calculations so that the use of strong currents installed according to the need will reduce the rate of corrosion. To see the strong influence of current on the rate of corrosion, it takes data on the corrosion rate of the last 5 years from 9 vessels and also the number of zink anodes used each year. From the graph of the results of the calculation of strong current according to the theory and the results of the use of zinc anodes on nine vessels, the results obtained it is clear that the installed current strength must meet the needs of each vessel because it will affect the decrease in corrosion rate. On vessel No.3, an excess current strength of 0.539Amp to 1,386 Amp, a decrease in corrosion rate reaching 0.0317 mm/year in the 5th year. On vessel No. 4, an excess current strength of 0.444 Amp to 1.822 Amp there is a decrease in corrosion rate reaching 0.0138 mm/year in the 5th year. On vessel No. 9, an excess strong current of 4,894 Amp to 5,793 Amp there is a decrease in corrosion rate reaching 0.0371 mm/year in the 5th year.

Influence of Non-metallic Inclusions on Corrosive Properties of Polar Steel

Polar steel requires excellent toughness and corrosion resistance for breaking icy surfaces in low-temperature seawater environments. In this study, the effect of inclusions on the corrosion resistance of polar steel was examined. In the experiments conducted, the composition and morphology of the inclusions in steel were controlled using different deoxidation methods during steel refining. The morphology and composition of the corrosion-resistant active inclusions were analyzed using scanning electron microscopy and energy dispersive spectroscopy. The corrosion resistance of polar steel was determined by measuring the saturation current density of the anodic dissolution of steel in a corrosive medium via an electrochemical method. The corrosion resistance under simulated seawater was also investigated under laboratory conditions. It was found that as the ratio of Al/Mg approaches the stoichiometric composition of the spinel (2.3–2.5), the inclusions become less active; as the ratio increases further, the corrosion-resistant activity increases due to the formation of MgAl2O4⋅CaO complexes, leading to an increase in local stress around the inclusions. If steel is deoxidized with Zr–Ti, small Zr–Ti complex oxides form in the steel, providing nucleation particles for the precipitation of spheroidized and uniformly distributed MnS. Therefore, steel deoxidized with Zr–Ti has better seawater corrosion resistance than Al-deoxidized steel.

Strength of double-reinforced adhesive joints

The use of adhesive joints is increasing in aerospace, aviation, automotive, construction and marine industry due to their easily applicable properties, low-costs and light weights compared to traditional jointing methods such as bolts, rivets, welding and soldering. Due to the high fatigue strength, resistance to seawater corrosion and light weight, aluminum alloys, with their high satiety, fracture strength, light weight, high specific strength and good dimensional stability and other properties, glass fiber reinforced composite materials have widespread uses.

Novel green manufacture of metallic aluminum coatings on carbon steel by sol–gel method

The novel double-layer specimen of Al coating had the ability to resist simulated seawater corrosion for 30 days and air oxidation at 500 °C for 15 h.

Surface Modification of Aluminium Alloy by a Silver Nanoparticle-Doped Coating and Examination of Anticorrosion Protection

Aluminium alloys are among the metals that can be easily passivated, demonstrating notable anticorrosion properties. Under aggressive environments, like in seawater, corrosion may appear though due to presence of chloride ions (pH>8.5) leading to pitting failures. The objectives of the presented research were to examine the possibility of functionalizing the surface of an aluminium alloy through a polydopamine (PDA) layer with homogeneously dispersed silver nanoparticles (AgNPs) and examine the corrosion behaviour of the nanostructured coating. The development of a PDA coating provides a promising approach for immobilization of silver nanoparticles onto AA6061 substrate. Exposure to salt spray for 60 h and assessment of the corrosion status through various methods were applied. Depending on the process parameters for the fabrication of the PDA-AgNPs layer, an enhanced corrosion protection was achieved compared to the undoped with AgNPs film and the uncoated Aluminium alloy.

Fabrication of Ni–Co–P Alloy Coatings Using Jet Electrodeposition with Varying Reciprocating Sweep Speeds and Jet Gaps to Improve Wear and Seawater Corrosion Resistance

Type 45 steel substrate surfaces were coated with Ni–Co–P alloy coatings using jet electrodeposition in varying reciprocating sweep speed and jet gap to improve the wear and seawater polarization resistance of the substrate surface. The properties of the deposited coatings were analyzed and characterized. The results showed that the morphologies of the cross-section, thickness, and chemical composition of coatings were affected by reciprocating sweep speed and jet gap variation. At a reciprocating sweep speed of 175 mm·s−1 coupled with a jet gap of 2.0 mm, the content of Co element in the deposit attained the highest value of 47.66 wt.%. Reciprocating sweep speed and jet gap variation exhibited no significant influence on either the phase structure or the peak intensities of deposited Ni–Co–P coatings, but an obvious preferred orientation was evident in the (111) plane. Further increase in reciprocating sweep speed and jet gap caused an initial increase in the microhardness of Ni–Co–P alloy coatings followed by a decrease, where the highest value attained was 635 HV0.1. At a jet gap of 2.0 mm and a reciprocating sweep speed of 175 mm·s−1, Ni–Co–P alloy coatings reached a minimum wear scar width value of 460 µm. Electrochemical tests showed that the seawater corrosion resistance of coatings exhibited an observable change with increased reciprocating sweep speed and jet gap. The Ni–Co–P alloy coatings exhibited the highest polarization resistance (Rp) of 28.32 kΩ·cm−2 when the reciprocating sweep speed was 175 mm·s−1 and the jet gap was 2.0 mm, which indicated that the coatings had better seawater corrosion resistance.

Study on the classification of seawater corrosivity of typical sea areas in China

In order to evaluate the seawater corrosivity of typical sea areas in China and provide guidance for the seawater corrosion protection on marine equipment and facilities, field exposure test was carried out. These typical sea areas under various climatic zones in China included Qingdao, Zhoushan, Sanya and a South China Sea reef, and Q235, copper, 5083 aluminum alloy and 304 stainless steel were chosen as test materials. The continuous monitoring of seawater environmental factors (temperature, salinity, pH, dissolved oxygen, etc.,) and the statistical work of first-year corrosion rates of test materials were done. Then, based on the metal corrosion rates method and the environmental factors method, the seawater corrosivity of these typical sea areas in China were classified, respectively. Furthermore, the classification results from the two methods were compared and analyzed.