Summary

Eng (ISSN 2673-4117) is an international, peer-reviewed open access journal which publishes original papers, critical reviews, rapid communications, technical notes, and discussions on all areas of engineering. Eng's aim is to encourage scientists to publish their experimental and theoretical research relating to engineering science and technology in as much detail as possible. There is no restriction on the maximum length of the papers. Launched in 2020, Eng was indexed in Scopus in 2023. The journal was subsequently included in the Emerging Sources Citation Index (ESCI, Web of Science) in March 2024 and Ei Compendex in April 2025. It holds a 2025 Impact Factor of 3.5 and is ranked JCR Q1 in the “ENGINEERING, MULTIDISCIPLINARY” category. Its 2025 CiteScore is 4.1, and it currently ranks Q2 in Scopus’ “Engineering (miscellaneous)” category.

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Topic Review
Ceramic Matrix Composites
Ceramic matrix composites are multiphase materials in which a continuous ceramic matrix is reinforced with a dispersed second phase, usually in the form of fibers, whiskers, or particles, to overcome the inherent brittleness and low fracture toughness of monolithic ceramics [1]. The ceramic matrix—such as silicon carbide, alumina, silicon nitride, or a glass-ceramic—binds and protects the reinforcement, while the incorporated fibers or particles deflect cracks, bridge crack faces, promote fiber pull-out, and absorb fracture energy, raising toughness and damage tolerance relative to the unreinforced ceramic [2]. They are distinguished from monolithic ceramics and from metal and polymer matrix composites by the combination of a ceramic continuous phase with a ceramic or high-temperature reinforcement, which retains high-temperature strength, oxidation resistance, and hardness while mitigating catastrophic failure [1]. The defining principle is that the interface between matrix and reinforcement is engineered so that cracks are diverted and energy is dissipated rather than propagating catastrophically, and the mechanical behavior is governed by matrix reinforcement interaction, fiber-matrix bonding, and the resulting toughening mechanisms [2]. Their defining feature is a ceramic continuous phase toughened by a reinforcing second phase [3].
  • 12
  • 26 Sep 2026
Topic Review
Luminescent Phosphors
Luminescent phosphors are photoluminescent materials, typically crystalline inorganic hosts doped with activator ions, that absorb energy and re-emit it as light, usually in the visible spectral range, through radiative transitions within localized luminescence centers [1]. The host lattice provides the structural and electronic framework, while small concentrations of activator ions—such as rare-earth or transition-metal ions—introduce discrete energy levels within the band gap that capture excitation energy and relax radiatively by emitting a photon of characteristic wavelength; co-dopants may act as sensitizers that transfer absorbed energy to the emitting center [2]. A phosphor is distinguished from a generic luminescent material by its deliberate engineering of activator and sensitizer centers in a stable crystalline host to produce efficient, color-controlled light emission, and its behavior is governed by the energy-level structure of the luminescence centers and by energy transfer between them rather than by band-to-band recombination [1]. The emission color and efficiency depend on the choice of host and activator, the concentration of the luminescence centers, and non-radiative loss pathways, so that the material is defined by its ability to convert excitation into narrow-band visible light through these impurity-induced centers [2]. Its defining feature is controlled light emission via dopant luminescence centers in a crystalline host [3].
  • 16
  • 26 Sep 2026
Topic Review
Microwave Absorption
Microwave absorption is the process by which a material converts incident electromagnetic energy in the microwave frequency range into other forms of energy, principally heat, thereby reducing the energy that is reflected or transmitted from the material. When a microwave enters an absorbing material, its electromagnetic energy is dissipated through dielectric and magnetic loss mechanisms associated with the material’s complex permittivity and permeability, including conduction loss, dielectric polarization and relaxation, and magnetic resonance losses [1][2]. Effective microwave absorption requires both impedance matching, which facilitates the entry of electromagnetic waves into the material by minimizing surface reflection, and sufficient attenuation, which dissipates the electromagnetic energy that has entered the material. The absorption behavior is therefore governed by the frequency-dependent electromagnetic properties, impedance matching, and thickness of the absorbing layer [1][3]. In a real material, incident electromagnetic energy can be distributed among reflection, transmission, and absorption. Microwave absorbers are designed to favor the entry of electromagnetic waves into the material and their subsequent dissipation rather than strong surface reflection. For a metal-backed absorber, transmission is suppressed by the conductive backing, so the absorption performance is primarily determined by the reduction of reflection at the front surface [1]. Microwave absorption is related to, but distinct from, electromagnetic interference (EMI) shielding: shielding effectiveness can involve reflection, absorption, and multiple internal reflections, whereas microwave absorbers are specifically designed to minimize reflection and promote energy dissipation within the absorbing medium [2][3]. Microwave absorption performance is commonly evaluated by the fraction of incident electromagnetic power absorbed over a specified frequency band and is strongly dependent on dielectric and magnetic losses and impedance matching [1][2][3].
  • 28
  • 30 Sep 2026
Topic Review
Neutron Irradiation
Neutron irradiation is the exposure of a material to a flux of neutrons, which, because neutrons are uncharged, penetrate deeply and interact with atomic nuclei rather than being stopped by the electron cloud, producing displacement damage and, in some cases, transmutation products within the material [1]. The primary consequence in structural materials is the creation of lattice defects: an energetic neutron transfers kinetic energy to an atom, knocking it from its lattice site into an interstitial position and leaving a vacancy, and such primary knock-on atoms generate cascades of further displacements whose accumulated point defects evolve into dislocation loops, voids, and clusters under continued exposure [2]. Neutron irradiation is distinguished from charged-particle irradiation by the neutrality and deep penetration of the incident particle, which enables bulk rather than surface damage, and from simple thermal exposure by the displacement cascades and transmutation elements introduced by nuclear reactions [1]. The effects on properties—changes in strength, ductility, swelling, and embrittlement—arise from the accumulation and rearrangement of irradiation-induced defects and from transmutation gases, and are characterized in terms of displacement dose, typically expressed as displacements per atom [2]. Its defining mechanism is nuclear interaction producing atomic displacements deep within the solid [3].
  • 13
  • 26 Sep 2026
Topic Review
Bioelectrocatalysis
Bioelectrocatalysis is the acceleration of electrochemical reactions at an electrode by biological catalysts, principally redox enzymes, which lower the activation energy of electron-transfer reactions while performing the conversion at mild conditions and with high specificity [1]. In bioelectrocatalysis, a redox enzyme immobilized at or near an electrode catalyzes the oxidation or reduction of a substrate by exchanging electrons with the electrode either directly, through intimate electrical contact between the enzyme's active site and the conductive surface, or indirectly, through a redox mediator that shuttles electrons between the enzyme and the electrode [2]. The field is defined by the coupling of biological catalysis—exploiting the selective active sites of enzymes—to an electrode, so that a biochemical reaction is coupled to the flow of electric current and the electrode acts as the terminal electron donor or acceptor [1]. Bioelectrocatalysis is distinguished from conventional electrocatalysis, in which inorganic catalysts drive electron transfer, by the use of biological macromolecules as the catalytic species and by the dependence of the reaction on enzyme structure and on the electrical communication between the enzyme and the electrode [2]. Its defining feature is the biological mediation of electrode electron transfer [3].
  • 6
  • 26 Sep 2026
Topic Review
Laser Cladding
Laser cladding is a surface engineering process in which a laser beam is used to fuse a layer of added material—delivered as powder or wire—onto a metallic substrate, producing a metallurgically bonded coating of controlled composition with limited dilution of the substrate [1]. The laser rapidly melts the clad material together with a thin surface layer of the substrate, and the resulting extremely high cooling rates generate a fine, rapidly solidified microstructure while the coating remains firmly bonded to the underlying part rather than being merely a loosely adherent layer [2]. The process is defined by the use of a focused laser as the localized heat source and by the objective of depositing a functional layer that imparts wear, corrosion, or high-temperature resistance to the surface without substantially altering the bulk component [1]. Laser cladding is distinguished from laser surface alloying and laser hardening by the deliberate addition of clad material, and from conventional welding by the precise, localized, and low-heat-input nature of the laser process, which controls dilution and minimizes distortion; the geometry and properties of the clad are governed by laser power, travel speed, and material feed rate [2]. Its defining characteristic is the creation of a strongly bonded, rapidly solidified surface layer through laser fusion [3].
  • 7
  • 26 Sep 2026
Topic Review
Steelmaking Slag Dynamics
Steelmaking slag dynamics refers to the behavior, motion, and evolution of the molten oxide layer—the slag—that floats on top of the liquid steel bath during steelmaking, and specifically to the transport, reactions, and physical changes of this slag phase as the process proceeds [1]. The slag is a heterogeneous liquid mixture of oxides such as CaO, SiO₂, FeO, Al₂O₃, MgO, and MnO, and its dynamics encompass the emulsification and settling of metal droplets in the slag, the transfer of oxygen and solutes between slag and metal, the formation and collapse of foamy slag, and the evolution of slag composition, viscosity, and temperature as fluxes dissolve and impurities are refined out of the bath [2]. It is distinguished from the static thermodynamic properties of a slag by its emphasis on motion and kinetics: how the slag moves, mixes, entrains metal, exchanges constituents with the bath, and changes its physical state under stirring and gas injection [1]. The defining feature is the coupled chemical and physical interaction at the slag–metal interface, where mass transfer and buoyancy-driven flow govern refining efficiency and process control, so that the slag is an active, dynamically evolving reaction layer rather than a static cover [2]. Its behavior is governed by interfacial phenomena, density and viscosity differences, and gas stirring [3].
  • 11
  • 26 Sep 2026
Topic Review
Metal Solidification
Metal solidification is the phase transformation in which a liquid metal or alloy cools below its liquidus temperature and crystallizes into a solid, involving the nucleation of stable solid grains from the undercooled liquid and their subsequent growth through the moving solid–liquid interface [1]. The process is governed by the coupling of heat flow, solute redistribution, and interface morphology: as the solid advances, latent heat must be removed to the surroundings, and rejected solute accumulates in the liquid ahead of the interface, producing constitutional undercooling that destabilizes a planar front into cellular or dendritic growth [2]. Solidification is distinguished from simple freezing of a pure substance by the fact that alloys solidify over a temperature interval between the liquidus and solidus, partition solute between the phases, and develop a microstructure—grain structure, dendrite arm spacing, and segregation—whose scale is set by the local thermal gradient and growth velocity [1]. The defining physics is the motion of a solid–liquid interface driven by heat extraction and the resulting morphological instability, which determines as-cast structure, segregation, and defect formation, rather than being a mere transition from liquid to solid at a single melting point [2]. It comprises nucleation and growth controlled by undercooling, heat transfer, and solute transport [3].
  • 8
  • 26 Sep 2026
Topic Review
Corrosion Inhibition
Corrosion inhibition is the process by which a substance, the corrosion inhibitor, added in small concentration to a corrosive environment reduces the rate at which a metal undergoes electrochemical degradation, by interacting with the metal surface or with the electrochemical reactions occurring at the interface [1]. Inhibitors act by adsorbing onto the metal surface to form a protective film that blocks anodic dissolution sites, by suppressing the cathodic reduction reaction, by passivating the surface through formation of an insoluble layer, or by scavenging corrosive species, so that the corrosion current and hence the penetration rate are lowered without necessarily preventing corrosion entirely [2]. The mechanism is fundamentally interfacial: the inhibitor molecule or ion competes with water and aggressive ions for surface sites, and its effectiveness depends on adsorption strength, surface coverage, and the nature of the electrolyte and the metal, rather than on changing the bulk corrosive medium [1]. Corrosion inhibition is distinguished from coatings and barrier protection by the fact that the active agent is dissolved or dispersed in the environment and functions through surface adsorption and electrochemical interference, and it is characterized by the degree to which it slows the anodic and cathodic half-reactions at the corroding interface [2]. It is quantified as a reduction in corrosion rate relative to the uninhibited medium [3].
  • 8
  • 26 Sep 2026
Topic Review
Friction Welding Techniques
Friction welding techniques are a family of solid-state joining processes in which heat is generated by mechanically rubbing two workpieces against each other under an applied compressive force, bringing the material at the interface into a plasticized state without melting, after which the relative motion is stopped and an upset force forges the parts together into a coherent bond [1]. In conventional rotary and inertia friction welding, one part is rotated relative to the stationary part while being pressed against it, and in friction stir welding a non-consumable rotating tool traverses along a joint, its shoulder and probe generating frictional heat that plasticizes the surrounding material and stirs it into a consolidated seam [2]. Because the material never fully melts, friction welding is distinguished from fusion welding by the solid-state nature of the bond, which relies on severe plastic deformation, dynamic recrystallization, and intimate contact at temperatures below the equilibrium melting point [1]. The process is defined by conversion of mechanical energy into interfacial heat, followed by axial forging that expels contaminated interface material as flash, so that the joint forms in the solid state and is governed by the temperature, pressure, and material flow in the stirred or rubbed region [2]. These techniques share the generation of interfacial heat by friction and the absence of bulk liquid formation [3].
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  • 26 Sep 2026
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