Potential Uses of Copper Wastes in the Building Sector: Inertization and Added Value Solutions

Mining activity is the second biggest producer of waste in the European Union (EU), so to develop processes that allow the reuse of waste and the consequent creation of markets for these secondary raw materials are relevant for a desirable transition to a circular economy. Copper waste such as cakes, tailings, pyrite roasting residues, or slags present very different physical characteristics and hazards. There are two important aspects to consider for the residue of hazardous determination and its reuse: the particle size and the leaching behavior. Also, the reactive or non-reactive property of the waste depends on their origin, which is important for new applications. Based on these parameters (and other specifics for each application), the intention of this paper is to review and study the different applications of copper residues, aiming for new possibilities of cement-based construction materials with added value that allow to economically justify the use of cement.

Cynodon dactylon Mediated Synthesis of Selenium Nanoparticles and Its Antimicrobial Activity Against Oral Pathogens

is a genus of plant in the grass family. It is found in the tropical regions and is also known as grass, Bermuda grass and Indian Doab. It is a herb extensively used in Indian system of medicine. It has many health benefits and is useful in controlling hypertension, skin diseases and diabetes. Selenium particles have an excellent anti-cancer, , antioxidant, photo reactive property. The size of SeNPs ranges from 30nm to 200 nm. These particles can be used in arthritis, cancer, diabetes etc. To prepare the selenium particles using Cynodon , fresh Cynodon was dried and made into a fine powder and powder mixed with distilled water. Selenium were synthesized using plant extract and sodium . Anti microbial activity against oral pathogens tested usingagar well diffusion method. The diameter of zone of inhibition was recorded on each plate. The change was indicative of the formation of SeNPs that was further confirmed by . The Cynodon mediated SeNPs showed high anti microbial activity against all the three micro-organisms especially Candida and S.. Therefore, diseases can be prevented as it is very effective in inhibiting the growth of the colonies.

Investigation of Microstructure in Friction Stir Welded Al-Cu-Li Alloy

It is well known that the addition of Li to aluminum alloys offers an attractive combination of low density and high modulus, which are useful for lightweight structures of aerospace vehicles. However, microstructure of Al-Li alloys are complex, which consist of a number of equilibrium and metastable phases. In addition, Al-Li alloys are weldable but the weldability is not as good as that of other aerospace alloys. This is due to the reactive property of element Li during melting and causes porosity, cracking and low joint efficiency. In friction stir welding (FSW), rotating welding tool generates frictional heat and by keeping the tool rotating and moving speed, the heat from friction causes the plate to soften without melting. Therefore, this solid state welding is adequate to Al-Li alloys. The friction stir welded joint was divided into 9 regions and each microstructure was investigated in detail to present the microstructure evolution and material flows during friction stir welding process. The recrystallized structure is observed in nugget zone and the evidence of initiation of dynamic recrystallization is found around the boundary between thermo-mechanically affected zone (TMAZ) and nugget region. This paper describes the results of a study to investigate the microstructure change of Al-Cu-Li alloy during the friction stir welding process.

Tensile Properties and Microstructure of Friction Stir Welded Joints 2195-T8 Aluminum Alloy

Friction stir welding is a widely used welding process for aluminum alloys because it avoids many of the problems of conventional fusion welding. This process is beneficial especially for lithium containing aluminum alloys in which the reactive property of element Li causes porosity and hot cracking during melting and solidification. In friction stir welding process, each region undergoes different thermo-mechanical cycles and produces a non-homogeneous microstructure. In the present study, the mechanical properties and microstructure of a 2195-T8 aluminum alloy joined with friction stir welding were investigated. The change in microstructure across the welded joint was found to correspond to microhardness measurement. The microstructure was characterized by the presence of severely deformed grains and fine recrystallized grains depending on the region. Tensile tests shows the optimum condition was obtained at the tool rotating speed of 600rpm and the traveling speed range from 180 to 300mm/min.