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The purpose of this paper is to evaluate the effect of micro-nano mixed super-hydrophobic structure on corrosion resistance and mechanism of magnesium alloys.

A super-hydrophobic surface was fabricated on AZ91 and WE43 magnesium alloys by laser etching and micro-arc oxidation (MAO) with SiO₂ nanoparticles coating and low surface energy material modification. The corrosion resistance properties of the prepared super-hydrophobic surfaces were studied based on polarization curves and immersion tests.

Compared with bare substrates, the corrosion resistance of super-hydrophobic surfaces was improved significantly. The corrosion resistance of super-hydrophobic surface is related to micro-nano composite structure, static contact angle and pretreatment method. The more uniform the microstructure and the larger the static contact angle, the better the corrosion resistance of the super-hydrophobic surface. The corrosion resistance of super-hydrophobic by MAO is better than that of laser machining. Corrosion of super-hydrophobic surface can be divided into air valley action, physical shielding, pretreatment layer action and substrate corrosion.

The super-hydrophobic coatings can reduce the contact of matrix with water so that a super-hydrophobic coating would be an effective way for magnesium alloy anti-corrosion. Therefore, the corrosion resistance properties and mechanism of the prepared super-hydrophobic magnesium alloys were investigated in detail.

A very wide variety of alloy types are available for selection to combat the potential corrosion problems posed in a diverse range of industries. Although in today's climate cost reduction is an important goal, the price of unexpected failure of equipment is often measured as risk to human life, and materials selection must always be given a prime place in design, engineering and construction. Material selection should not be based simply on low installed cost of equipment — the need to maintain safety standards and effective long‐term utilization of a production asset, with minimum costly maintenance and downtime, mandate the selection of materials which can be justified on the basis of life‐cycle cost and risk analysis. The material chosen should provide the lowest cost viable, and if possible, “fit and forget” solution. In the Offshore Oil and Gas industry in the North Sea the solution adopted would need to address the CRINE cost reduction strategy.

Results of DC electrochemical measurements of four Ni‐base alloys are presented. The tests were conducted in 1 percent sulphuric acid, containing 0.2 percent chlorides at temperature 353K. Gravimetric test, performed in the same conditions, revealed excellent properties of alloy signed A3. Pitting corrosion of alloy A4 at the test conditions after long exposure at 353K was observed and was confirmed by the applied tests. The multiple anodic polarization (MAP) method is proposed to control alloys’ susceptibility to pitting corrosion.

States that duplex (austenitic/ferritic) stainless steels offer properties of interest and a cost‐effective material selection solution for plant and equipment in the pulp and paper industry. Reviews characteristics of duplex steels leading to successful long‐term applications of 22 Cr duplex and a copper containing 25 Cr super duplex stainless steel. Concludes that, applied correctly, two‐phase stainless steels can provide long‐term reliable maintenance‐free service in many pulp and paper plant environments.

The first major nickel alloy introduced to the industry, about 100 years ago, was a Ni‐Cu alloy 400. This alloy is still widely used in a variety of industries and will continue to be used in this current century. Over the past 100 years, especially in the last 50 years, improvements in alloy metallurgy, melting technology, and thermo‐mechanical processing, along with a better fundamental understanding of the role of various alloying elements has led to new nickel alloys. These have not only extended the range of usefulness of existing alloys by overcoming their limitations, but are reliable and cost‐effective and have opened new areas of applications. This paper briefly describes the various nickel alloy systems developed during the last 100 years and comments on what the future holds for the newer alloys developed in the last 20 years and on the competition faced by these alloys in the new millennium. High‐temperature alloys are not discussed in this paper.

Inconel 617 alloy is widely used in industry due to its superior high temperature properties. After long periods of operation, the alloy microstructure changes. One of the methods to regain the alloy microstructure is heat treatment at elevated temperatures. In the present study, electrochemical and mechanical responses of Inconel 617 alloy over 30,000 hours of operation as a transition‐piece in agas turbine engine are examined. The heat treatment process at two different temperature levels is applied when refurbishing the alloy microstructure. The electrochemical tests are conducted to investigate the corrosion response of the alloy before and after the heat treatment process. Fatigue and tensile tests are carried out for the workpieces subjected to the electrochemical tests. SEM is introduced to examine the fractured surfaces.

Electron beam melting (EBM) is one of the potential additive manufacturing technologies to fabricate aero-engine components from gamma titanium aluminide (γ-TiAl) alloys. When a new material system has to be taken in to the fold of EBM, which is a highly complex process, it is essential to understand the effect of process parameters on the final quality of parts. This paper aims to understand the effect of melting parameters on top surface quality and density of EBM manufactured parts. This investigation would accelerate EBM process development for newer alloys.

Central composite design approach was used to design the experiments. In total, 50 specimens were built in EBM with different melt theme settings. The parameters varied were surface temperature, beam current, beam focus offset, line offset and beam speed. Density and surface roughness were selected as responses in the qualifying step of the parts. After identifying the parameters which were statistically significant, possible reasons were analyzed from the perspective of the EBM process.

The internal porosity and surface roughness were correlated to the process settings. Important ones among the parameters are beam focus offset, line offset and beam speed. By jointly deciding the total amount of energy input for each layer, these three parameters played a critical role in internal flaw generation and surface evolution.

The range selected for each parameter is applicable, in particular, to γ-TiAl alloy. For any other alloy, the settings range has to be suitably adapted depending on physical properties such as melting point, thermal conductivity and thermal expansion co-efficient.

This paper demonstrates how melt theme parameters have to be understood in the EBM process. By adopting a similar strategy, an optimum window of settings that give best consolidation of powder and better surface characteristics can be identified whenever a new material is being investigated for EBM. This work gives researchers insights into EBM process and speeds up EBM adoption by aerospace industry to produce critical engine parts from γ-TiAl alloy.

This work is one of the first attempts to systematically carry out a number of experiments and to evaluate the effect of melt parameters for producing γ-TiAl parts by the EBM process. Its conclusions would be of value to additive manufacturing researchers working on γ-TiAl by EBM process.

This paper seeks to review the industrial applications of state‐of‐the‐art additive manufacturing (AM) techniques in metal casting technology. An extensive survey of concepts, techniques, approaches and suitability of various commercialised rapid casting (RC) solutions with traditional casting methods is presented.

The tooling required for producing metal casting such as fabrication of patterns, cores and moulds with RC directly by using different approaches are presented and evaluated. Relevant case studies and examples explaining the suitability and problems of using RC solutions by various manufacturers and researchers are also presented.

Latest research to optimize the current RC solutions, and new inventions in processing techniques and materials in RC performed by researchers worldwide are also discussed. The discussion regarding the benefits of RC solutions to foundrymen, and challenges to produce accurate and cost‐effective RC amongst AM manufacturers concludes this paper.

The research related to this survey is limited to the applicability of RC solutions to sand casting and investment casting processes. There is practically no implication in industrial application of RC technology.

This review presents the information regarding potential AM application – RC, which facilitates the fabrication of patterns, cores and moulds directly using the computer‐aided design data. The information available in this paper serves the purpose of researchers and academicians to explore the new options in the field of RC and especially users, manufacturers and service industries to produce casting in relatively much shorter time and at low cost and even to cast complex design components which otherwise was impossible by using traditional casting processes and CNC technology.

This paper aims to investigate hot corrosion behaviour of different Cr₃C₂–NiCr coatings on boiler tube steel.

High velocity oxy fuel technique has been used to deposit different coatings on commercially available ASTM-SA213-T22 boiler tube steel. The hot corrosion studies have been performed in molten salt environment at 900°C temperature in silicon tube furnace in laboratory.

The results showed that uncoated superalloy suffered intense spalling and the weight change was massive during each cycle on studies of hot corrosion 900°C. The 100 per cent NiCr and 10 per cent (Cr₃C₂) – 90 per cent (NiCr) coatings provided better protection to T22 steel against the hot corrosion because of the formation of Ni and Cr₃C₂ layers.

In this research a variety of coatings have been used. This research work has been aimed to investigate the hot corrosion behavior of Boiler Steel b with different Cr₃C₂–NiCr coatings, under molten salt environment in Silicon tube furnace at 900°C, under cyclic conditions.