Şükrü Çetinkaya

Artificial composite stones have recently attracted attention as multifunctional materials for construction and defense-related applications. In this study, a novel composite stone was developed using waste limestone as the primary mineral filler, combined with an unsaturated polyester resin matrix and reinforced with glass powder and chopped glass fibers. The influence of binder content and reinforcement type on physico-mechanical and microstructural behavior was investigated. Experimental characterization included water absorption, compressive strength, abrasion resistance, acid resistance, and optical microscopy. The results demonstrated that fine fillers improved matrix densification and reduced porosity, while short glass fiber reinforcement enhanced load-bearing capacity. Abrasion resistance and durability were found to depend on binder content and particle packing characteristics. Overall, the developed composite material exhibits promising mechanical performance, low water absorption, and improved durability, suggesting its potential as a candidate material for applications requiring environmental resistance, including potential use in defense-related camouflage applications.

This study investigates the production of implant-like porous pure titanium materials for biomedical applications, produced by powder metallurgy (T/M). The material consists of a solid titanium core and a porous titanium outer layer designed to enhance bone conformability and strength. Magnesium powder (50 µm) was used in proportions of 10, 20 and 30 wt% to create the porous structure. The samples were sintered in argon atmosphere at 1000°C, 1100°C and 1200°C for different times (60, 90 and 120 minutes) and Magnesium was removed. The experimental work was carried out by tensile stripping test in a tensile testing machine. The effects of sintering temperature, time and grain size were analyzed by Taguchi method. ANOVA and Signal-to-Noise (S/N) ratio analyses were applied to evaluate joint quality and optimize strength. The findings contribute to the understanding of cost-effective design parameters for high-strength porous titanium implants, highlighting the influence of processing conditions on mechanical performance.

Due to its super plasticity, low weight, and high mechanical resistance properties, generally, Ti6Al4V is used for aeronautical applications. However, it has low resistance to plastic shearing. In addition, it has poor wear resistance. For these reasons, a lot of techniques have been developed to improve its wear resistance. Investigations of microstructure and interfacial reactions of diffusion bonding of Ni and Ti6Al4V materials have been performed experimentally. Ni samples were prepared with 50 ± 5 µm Ni powders in cylindrical shape. For diffusion bonding, Ag foil was used for improving the interlayer and connection quality. Nickel and its alloys can be joined by using some different processes, and the use of an interlayer can further facilitate the joining process and improve the joint quality. The experiments were carried out under the protected atmosphere. Argon gas was used for protection. The experiments were performed under 5 MPa pressure for 60 min duration at 850 °C, 900 °C, and 950 °C thermal conditions. Investigations of metallurgical structure occurring in the interface areas were examined by optic analysis of EDS, SEM, and X-ray. The strength of the joints was tested by lap-shear tests. From observations, the best quality of the coalescence at interfaces was indicated at elevated temperatures.