Slippery Surface with Petal-like Structure for Protecting Al Alloy: Anti-corrosion, Anti-fouling and Anti-icing

The harsh working environment affects the performance and usage life of Al and its alloys, thus limiting their application. In recent years, Slippery Liquid-infused Porous Surface (SLIPS) has attracted much attention due to excellent anti-corrosion, anti-fouling and anti-icing properties. This may be an effective way to improve the properties of Al and its alloys. Here, the SLIPS with petal-like structure was constructed on the Al alloy via simple hydrothermal reaction, Stearic Acid (STA) modification and lubricant injection. A variety of droplets (including oil-in-water emulsions) can slide on the SLIPS at a low angle, even the Sliding Angle (SA) of the water droplet is only 3°. Furthermore, the SLIPS exhibits outstanding mechanical and chemical properties. It can maintain fine oil-locking ability under high shearing force and keep slippery stability after immersion in acid/alkaline solutions. In addition, the SLIPS possesses excellent anti-corrosion, anti-fouling and anti-icing properties, which provides a new way to promote the application of Al and its alloys. Therefore, the SLIPS is expected to be an effective way to improve the properties of Al and its alloys, as well as play a role in anti-fouling and self-cleaning in construction, shipbuilding and automotive manufacturing industries, thereby expanding the practical application of Al and its alloys.

Properties of Mg-based metal matrix nanocomposites processed by high shear dispersion technique (HSDT) - a review

: Metal Matrix Nanocomposites (MMNCs) often show excellent properties compared to their non-reinforced alloys due to either the achieved grain refinement or Orowan strengthening. Especially in light metals such as aluminium and magnesium as the matrix has the potential to be significantly improved in relation to mechanical properties. Functionalisation can also be achieved in some cases. However, the challenge lies in the homogeneous distribution of the ceramic nanoparticles in the melt, if MMNCs are processed via melt metallurgical processes. The large surface area of the nanoparticles generates large van der Waals forces which have to be overcome. Furthermore, the wettability of the particles with molten metal is difficult. Additional forces can be applied by ultrasound, electromagnetic stirring or even high-shearing. In this paper properties of MMNCs with a light metal matrix will be presented, which were produced with the High-Shearing Dispersion Technique. First, the process with its different characteristics and the underlying theory is presented and then property improvements are discussed by comparing MMNCs to their matrix materials.

35 “Ur” Type Anti-Tank Rifle– A Numerical Analysis of Armour Penetration of a World War II Tank

The paper presents a simulated process of penetration of a steel slab with a strength performance approximate to that of World War II battle tanks with a 7.92 mm DS projectile fired from the 35 “Ur” type anti-tank rifle. The basic technical parameters necessary for the simulation process were sourced from historical records. The FEM (Finite Element Method) applied in LS-Dyna enabled an estimation of the penetrating capability of the DS projectile. Decisive to the high penetrating capability of the DS projectiles were the non-optimized properties of armour steel (its high brittleness) and a high kinetic energy of the projectile, which generated high shearing stresses upon impact against the steel slab causing the effect of ‘plugging’ upon penetration. The numerical simulation results confirmed the high combat effectiveness of the DS projectile and the argument that the DS projectile could pierce a 20 mm thick armour plate made from the material applied during the World War II era.

Development of Chelating Agent-Based Polymeric Gel System for Hydraulic Fracturing

Hydraulic Fracturing is considered to be one of the most important stimulation methods. Hydraulic Fracturing is carried out by inducing fractures in the formation to create conductive pathways for the flow of hydrocarbon. The pathways are kept open either by using proppant or by etching the fracture surface using acids. A typical fracturing fluid usually consists of a gelling agent (polymers), cross-linkers, buffers, clay stabilizers, gel stabilizers, biocide, surfactants, and breakers mixed with fresh water. The numerous additives are used to prevent damage resulting from such operations, or better yet, enhancing it beyond just the aim of a fracturing operation. This study introduces a new smart fracturing fluid system that can be either used for proppant fracturing (high pH) or acid fracturing (low pH) operations in sandstone formations. The fluid system consists of glutamic acid diacetic acid (GLDA) that can replace several additives, such as cross-linker, breaker, biocide, and clay stabilizer. GLDA is also a surface-active fluid that will reduce the interfacial tension eliminating the water-blockage effect. GLDA is compatible and stable with sea water, which is advantageous over the typical fracturing fluid. It is also stable in high temperature reservoirs (up to 300 °F) and it is also environmentally friendly and readily biodegradable. The new fracturing fluid formulation can withstand up to 300 °F of formation temperature and is stable for about 6 h under high shearing rates (511 s−1). The new fracturing fluid formulation breaks on its own and the delay time or the breaking time can be controlled with the concentrations of the constituents of the fluid (GLDA or polymer). Coreflooding experiments were conducted using Scioto and Berea sandstone cores to evaluate the effectiveness of the developed fluid. The flooding experiments were in reasonable conformance with the rheological properties of the developed fluid regarding the thickening and breaking time, as well as yielding high return permeability.