Miguel Humberto Bocanegra-Bernal

Ceramic materials are indispensable to aerospace and defence technologies, where structural and functional components are required to withstand extreme thermal, mechanical, and chemically aggressive environments. Traditionally valued for their exceptional thermal stability, oxidation resistance, and corrosion resistance, ceramics have nonetheless been constrained by their inherent brittleness, which has limited their widespread adoption in load-bearing structural applications. This review surveys the principal tough ceramic systems currently employed in aerospace and defence, including SiC, Al₂O₃, ZrO₂, Si₃N₄, SiC/SiC composites, and ultra-high-temperature ceramics (UHTCs) such as ZrB₂ and HfB₂. In parallel, it outlines advanced processing and manufacturing routes that enable enhanced microstructural control, improved reliability, and scalability for industrial deployment. Special attention is devoted to thermal and environmental barrier coatings (TBCs and EBCs), which provide critical protection against oxidation, corrosion, and severe thermal cycling in propulsion, power-generation, and hypersonic systems. Finally, the review highlights key material selection criteria for aerospace and defence platforms and discusses emerging trends that integrate tough ceramics with next-generation manufacturing technologies, underscoring their pivotal role in enabling high-performance, durable, and resilient systems for future extreme-environment applications.

Magnetoelectric (ME) materials that exhibit simultaneous coupling between electric polarization and magnetization have attracted significant attention due to their potential technological applications in the emerging generation of multifunctional devices. In this research, Ba_0.85Ca_0.15Ti_0.92Zr_0.08O₃-CoFe₂O₄:x (x = 0.1, 0.2, 0.3% mol) composites were synthesized using solid-state and sol–gel combustion chemical methods to elucidate their ME coupling at ultra-low concentrations of the magnetic phase. Rietveld refinement and Raman spectroscopy results confirm a shift in the morphotropic phase boundary (MPB), evidenced by an increase in the tetragonal phase relative to the orthorhombic structure. High stability of the P4mm and Amm2 symmetries is reached at 1300 °C without diffusion of Fe and Co into the octahedral site. At this temperature, the CoFe₂O₄ spinel structure remains stable without secondary phases. The orthorhombic phase fraction decreases from 55% to 37% as the magnetic phase fraction increases, driven by stress and constraint rather than ionic interactions alone. The Curie temperature decreases from 99 to 90 °C, attributed to the grain-size reduction effect rather than structural disorder. The dielectric permittivity (ε_r) reaches an absolute value of 5070 and progressively decreases with increasing magnetic saturation. An increase in compressive residual stress is observed, which ensures the mechanical stability of the electroceramics. Magnetoelectric (ME) coupling, evaluated through measurements of electric polarization as a function of the magnetic field, shows an increase from 3.8 to 4.9 μC/cm² under a magnetic field of 50 Oe. The composites with x = 0.2 and 0.3 mol% exhibit potential for applications in fast-switching magnetoelectric devices and magnetic field sensors.

This study explores the relevance and limitations of conducting ballistic tests in outdoor shooting ranges without specialized laboratory equipment. While these methods lack the precision and control of fully equipped laboratories, they provide a cost-effective and practical alternative for evaluating material and armor performance in resource-limited contexts. Tests were carried out using 7.62 × 51 mm and 9 × 19 mm ammunition at velocities of 832 and 350 ms ¹ , respectively. Depth of Penetration (DOP) measurements were obtained directly from the deformed metallic backing plate, and Scanning Electron Microscopy (SEM) was employed to examine post-impact ceramic fragments. Results showed that higher areal density targets (65.41 kg·m ² ) offered greater resistance to 7.62 × 51 mm ammunition, while lower-density targets (53.15 kg·m ² ) were fully penetrated. Against 9 × 19 mm ammunition, targets with 64.85 and 65.41 kg·m ² densities effectively minimized deformation of the backing plate. Enhanced areal density improved ballistic efficiency, with certain targets meeting NIJ-0101.06 standards, indicating their potential for use in personal armor systems.

Recent advancements in composite materials, including ceramics, metals, and polymers, have shown significant promise for biomedical applications. In particular, the use of carbon nanotubes (CNTs) as reinforcement in alumina and zirconia ceramics has garnered attention due to their potential to greatly enhance mechanical properties. CNTs, with their high aspect ratio, mechanical strength, and electrical conductivity, offer unique advantages for improving traditional ceramics used in biomedical applications, such as hip and knee replacements, where alumina and zirconia have been employed since the 1970s for their superior wear resistance and biocompatibility. This review critically examines the mechanical benefits of CNT-reinforced ceramics, focusing on factors such as CNT distribution, reinforcement mechanisms, fracture toughness, and long-term durability. Additionally, it explores the significant challenge of CNT toxicity, cytocompatibility, and potential long-term health risks, particularly their non-biodegradable and carcinogenic nature, which could limit their use in medical implants. While promising, inconsistencies in reported improvements, largely due to dispersion issues and ceramic-CNT interactions, along with unresolved toxicity concerns, indicate the need for further research. This review aims to provide a comprehensive understanding of both the mechanical potential and the biological risks of CNT-reinforced ceramics in biomedical applications.