Search

This study investigates the wear characteristics of Al–25Mg2Si composite synthesized via gravity casting. The research aims to understand the influence of applied load, test temperature, contact condition (dry and lubrication), and sliding distance on wear characteristics. Results show that higher loads and temperatures lead to increased wear loss and coefficient of friction. The worn surface morphology for higher loads and temperature shows deeper scratches and grooves, indicating severity in wear. The debris size and volume increase with an increase in load and temperature. The dominant mechanism is abrasive, adhesive, and oxidative for both the room‐ and high‐temperature dry sliding conditions. However adhesive and oxidative wear increase with the increase in test temperature. Abrasive wear is the only wear mechanism present during the lubricating sliding condition. Wear transition is noticed during the wear map analysis subjected to load, temperature, and sliding distance. In the case of room‐temperature test, severe–moderate–mild wear transition occurs with the increase in sliding distance and mild–moderate–severe wear transition occurs with the increase in test temperature and applied load. The roughness of the worn surface increases with an increase in applied load and temperature and the use of lubricant hugely reduces the surface roughness. [ABSTRACT FROM AUTHOR]

This study aims to optimize the process parameters of wire arc additive manufacturing for ER70S6 steel and to build a machine‐learning (ML) model to predict the properties of deposited specimens. Process parameters such as current, voltage, and travel speed are optimized considering other process parameters constant (gas flow rate, contact tip to the work distance, and preheat). The optimization is made using the response surface method and validated the properties by experimentation, including tensile testing and metallography. A support vector regression (SVR) ML model is implemented to predict the material's properties to substantiate the outcomes' values in every possible combination for the given parameters. In the study's findings, a significant enhancement is revealed in specimen quality, marked by reduced irregularities and porosity, and a remarkable increase in ultimate tensile strength up to 40%, validated through the SVR model. In this study, a valuable path that can be extended to predict properties of other material systems is sketched. [ABSTRACT FROM AUTHOR]

The critical aspect of joining T23 steel to T91 steel in a supercritical boiler is studied by a low‐cost gas tungsten arc welding (GTAW) process using an iron‐based filler wire (ER90S‐G). The hardness variation across the weldment does not reflect any drastic fall in hardness, thereby indicating an absence of "soft zone." A significant joint strength (UTS = 318 MPa) together with a modest ductility (%Elongation = 6) is established by carrying out tensile test at boiler operation temperature (571 °C) and thereafter carrying out advanced characterization keeping all different regions of the weldment intact. During high‐temperature tensile deformation, Cr23C6 particles are found to be pushed along with grain boundary sliding and finally are clustered around the cavity formed thereby. The presence of Cr23C6 particles surrounding cavity promotes a cleavage mode of failure so as to negate a high ductility to be achieved. Yet, a modest ductility is still retained by virtue of soft α‐ferrite matrix promoting a concomitant dimple mode of failure. Furthermore, these Cr23C6 particles are also found to be responsible for an accumulation of dislocation loops around them, thereby providing quite significant high‐temperature strength with 88% joint efficiency. [ABSTRACT FROM AUTHOR]

The search for main‐group element‐based radicals is one of the main research topics in contemporary chemistry because of their fascinating chemical and physical properties. The Group 15 element‐centered radicals mainly feature a V‐shaped two coordinate structure, with a couple of radical cations featuring trigonal tricoordinated geometry. Now, nontrigonal compounds R3E (E=P, As, Sb) were successfully synthesized by introducing a new rigid tris‐amide ligand. The selective one‐electron reduction of R3E afforded the first stable tricoordinate pnictogen‐centered radical anion salts; the pnictogen atoms retain planar T‐shaped structures. EPR spectroscopy and calculations reveal that the spin density mainly resides at the p orbitals of the pnictogen atoms, which is perpendicular to the N3E planes. [ABSTRACT FROM AUTHOR]