Features of anodic plasma electrolytic treatment of an ultra-light alloy of the Mg-Li system in an aqueous electrolyte

The possibility of plasma electrolytic treatment of an alloy of the Mg-Li system in an aqueous solution of ammonium chloride, ammonium nitrate and boric acid has been studied. The specific features of the process in the voltage range from 10 to 600 V are determined. The current-voltage and voltage-temperature characteristics during alloy processing are shown, as well as the effect of the processing time on the temperature of the samples. Plasma electrolytic boronitriding of the alloy can be carried out to study the efficiency of the technology at avoltage of 240 V, which corresponds to a sample temperature of 300 ± 10 °C.

Protective and Thermophysical Characteristics of Plasma-Electrolytic Coatings on the Ultra-Light Magnesium Alloy

Magnesium alloys are now widely used for various purposes due to their unique properties despite the significant disadvantage associated with low corrosion resistance. The plasma-electrolytic oxidation (PEO), which allows the formation of ceramic coatings on the surface of magnesium alloys, is the most advanced and effective method for their protection. But firstly, PEO process of magnesium alloys has some difficulties, and secondly, PEO coatings affect the thermophysical characteristics of the modified materials, in particular they reduce thermal diffusivity. The presented work is devoted to the development of the technological parameters for formation of protective coating on the ultra-light alloy Mg-8Li-1Al-0.6Ce-0.3Y by the PEO method. The results analyses of electrolytes acidity and specific electrical conductivity before and after PEO process and also investigation data of the coatings structure and surface morphology are presented. An integral assessment of the ability of thermal diffusivity and corrosion resistance of the modified alloy was made. Studying of protective and thermophysical characteristics of the obtained coating showed that it provides a sufficiently high corrosion protection, despite the relatively small thickness, and the presence of pores and slightly (not more than 5%) reduces the thermal diffusivity of the magnesium ultra-light alloy.

Protection enhancing of threaded connections of light-alloy drill pipes against contact corrosion

When using light-alloy drill pipes (LAIDP) with steel tool joints, the development of contact corrosion is observed under certain operating conditions. The value of corrosion mainly depends on the difference in electrochemical potential (ECP) of the contacting metals. One of the effective methods for increasing the corrosion resistance of aluminum alloys is the micro-arc oxidation (MAO) method. This is an electrochemical process in combination with micro-arc-discharges phenomena at the anode-electrolyte border, which allows forming ceramic coatings of aluminum oxides on the surface, including its high-toughness and wear-resistant phase - α-Al2O3 (corundum). MAO-technology is a highly efficient and environmentally friendly process. At the forming of such a coating on the threaded part and in the tool joint zone of the pipe, a barrier for contact corrosion between the steel tool joint and the surface of the aluminum pipe is created. In this work, contact corrosion on samples in a pair of 1953T1 aluminum alloy - 40KhN2MA steel in a 5% NaCl solution at 80 °C was investigated. The data obtained showed the effectiveness of using protective MAO-coating to reduce contact corrosion and increase the reliability of the tool joint threaded connection of LAIDP.

Numerical Assessment of In-Line Rotor–Stator Mixers in High-Shear Melt Conditioning (HSMC) Technology

High shear melt conditioning technology refines the as-cast structure of light alloy melts, thereby improving the mechanical properties of the casting and reducing the occurrence of defects, without requiring chemical grain refiners. To upscale the technology and apply it to processes involving larger melt volumes, a computational fluid dynamics study is conducted with three rotor–stator mixers operating in both batch and continuous modes. Analysis of the results show that rotor–stator mixers with smaller stator holes outperform those with larger ones because of larger shear rates—increasing the deagglomeration rate—and larger volume flow rates—increasing the dispersion of the intensively sheared melt in the bulk liquid. Compared with batch mode, continuous operation results in lower mass flow rate through the mixer and reduced mixing, although the mixer design has a larger impact on both measures.

Superhydrophobic Light Alloy Materials with Corrosion-Resistant Surfaces

Metals and their alloys are irreplaceable engineered materials showing great importance in our society. Light alloy materials (i.e., Mg, Al, Ti, and their alloys) have tremendous application potential in the aerospace, automotive industries, and biomedical fields for they are lighter and have excellent mechanical properties. The corrosion of light alloys is ubiquitous and greatly restricts their utilization. Inspired by the natural anti-water systems, many new designs and conceptions have recently emerged to create artificial superhydrophobic surfaces with great potential for corrosion resistant of light alloy. This review firstly introduces the concept of superhydrophobicity and strategies of producing superhydrophobic surfaces to inhibit the corrosion of light alloys. In addition, we elaborate the durability of superhydrophobic light alloy materials for commercial and industrial applications, and present their anticorrosion mechanism in the corrosive media.

Characterization of Thermomechanical Boundary Conditions of a Martensitic Steel for a FAST Forming Process

The present work characterized and modelled the interfacial heat transfer coefficient and friction coefficient of a non-alloy martensitic steel, for a novel Fast light Alloy Stamping Technology (FAST) process. These models were validated through temperature evolution, thickness distribution and springback measurements on experimentally formed demonstrator components, which were conducted on a pilot production line and showed close agreement, with less than 10% variation from experimental results. The developed models and finite element simulations presented in this work demonstrate that non-isothermal processes can be precisely simulated with implementation of the accurate thermomechanical boundary conditions.