Matthew Davidson

Titanium and its alloys are cornerstone biomaterials due to their high strength-to-weight ratio, excellent fatigue and corrosion resistance, biocompatibility, and ability to osseointegrate with bone. Their relatively low elastic modulus compared to stainless steels and Co–Cr alloys further enhances their suitability for biomedical applications. Performance is continually improved through alloy design (tailoring α and β phases), advanced manufacturing methods such as CNC machining and additive manufacturing, and surface engineering approaches. In particular, the formation of a stable TiO₂ layer promotes corrosion resistance and cell attachment, while coatings and nanotexturing enhance osseointegration and provide antibacterial functionality. These attributes enable widespread use in orthopedic, dental, and cardiovascular implants. Emerging developments include smart implants with embedded sensors, multifunctional surfaces, and data-driven alloy design, aiming to further optimize mechanical performance, biological response, and long-term reliability. This review summarizes the processing techniques, properties, applications, and recent advances in titanium-based biomaterials.

Carbon Fiber-Reinforced Polymer (CFRP) composites represent a transformative class of structural materials, combining low density, high specific strength, and excellent fatigue resistance. This review provides a comprehensive overview of CFRPs, addressing their structure, manufacturing routes, mechanical performance, and functional behavior, with particular emphasis on damage tolerance, tribological properties, and environmental durability. The discussion begins with the classification and morphology of carbon fibers, highlighting their influence on composite anisotropy and interlaminar behavior. The effects of impact loading, delamination, and environmental conditioning on residual strength and fatigue life are then examined, with reference to established evaluation methods such as ASTM D7136 and compression-after-impact (CAI) testing. From a tribological perspective, the incorporation of nanoscale additives, such as graphite nanoplatelets and TiO₂ nanoparticles, and their contribution to enhancing wear resistance by promoting the formation of stable tribofilms, is explored. Advances in processing techniques, including low-pressure curing and improved resin systems, are also discussed for their roles in enhancing manufacturability and energy efficiency. Overall, the review underscores that optimal CFRP performance is achieved through the synergistic integration of fiber architecture, matrix design, and precise processing control, while future progress in nanomodification, recycling, and sustainable curing technologies is expected to further expand CFRP applications in the aerospace, automotive, and high-performance engineering sectors.