In this study, the mechanical behavior and interfacial bonding characteristics of multi-material composites produced using the Hybrid Fused Deposition Modeling (HFDM) technique were systematically investigated. Polylactic Acid (PLA), Polyethylene Terephthalate Glycol (PETG), and Acrylonitrile Butadiene Styrene (ABS) filaments were utilized within a single structure to explore the effects of material combinations on mechanical performance. Specimens were fabricated using two distinct levels of infill density (50–100%) and raster angle (45–90°) to evaluate the influence of these parameters on tensile strength, flexural resistance, and impact toughness. Experimental tests were conducted following ASTM standards, and microstructural examinations were performed using Scanning Electron Microscopy (SEM) to assess interfacial adhesion between different polymers. The results revealed that PETG demonstrated the highest tensile strength among single-material samples, while the PLA-PETG-ABS configuration exhibited notable mechanical stability among hybrid structures. Increasing infill density and raster angle significantly enhanced mechanical performance across all configurations. SEM analyses confirmed that interfacial bonding quality critically affected structural integrity, with better adhesion observed in PLA–PETG interfaces compared to PLA–ABS transitions. The potential of HFDM in developing tailored multi-material components with optimized mechanical properties offers valuable insights for the advancement of functional additive manufacturing applications in engineering fields.

In this study, the bonding properties of parts produced using additive manufacturing methods, which are frequently preferred today, were investigated. In this context, parts were produced by Stereolithography (SLA) and Fused Deposition Modelling (FDM) methods. The mechanical properties of the produced materials were determined by tensile test according to ASTM D638 standard. Afterwards, these parts were bonded in different combinations and the mechanical properties of the joints were determined according to ASTM D1002 standard. As a result, the tensile strength of Polylactic Acid (PLA) parts produced by FDM method was 65% higher than that of PhotoPolymer Resin (PPR) parts produced by SLA method, while the strain rates of PPR materials were 85% higher than PLA materials. When the failure load values obtained after the tensile test of the bonded joint specimens were examined, the best mechanical performance was obtained as 3086 N in the combination of PLA and composite material. The lowest damage load occurred in the combination of PPR and PLA material. When the displacement data resulting from the failure load were analysed, the highest values were obtained in the PPR-PPR material combination. In conclusion, bonding can be used for joining parts produced by additive manufacturing, but the choice of material should be based on the application.

In this study, the effect of hydrophobicity on the plate surface on heat transfer, pressure drop, and pump power was investigated without changing the existing designs of gasketed plate heat exchangers (GPHEs). The wet surfaces of the plate were coated with carbon-based polymer solutions with four different hydrophobic groups, that is, FEP, FH3, FH7, and FH10. To increase the hydrophobicity of the FEP material, a new coating solution was synthesized by adding 3, 7, and 10 wt.% h-BN nanoparticles. Heat transfer, pressure loss, and pump power performances of heat exchangers with hydrophobic surface coating were tested at five different Reynolds numbers and compared with the uncoated heat exchanger performance. Also, the efficiency analysis of the GPHE under different hydrophobic conditions was carried out. As a result, the addition of 3 and 7 wt.% h-BN nanoparticles increased the contact angle. However, the addition of 10 wt.% h-BN decreased the contact angle as it increased the rough structure and film thickness on the surface. It was determined that the heat exchanger efficiency increased proportionally with the increase in hydrophobicity. While the highest heat exchanger efficiency value was 0.525 in FH7 coated. However, it was found that there was a 25.6% decrease in heat transfer of FH7 coating compared to uncoated exchanger. The pressure drop of the FH7 surface-coated heat exchanger with the highest hydrophobicity was 207.6% lower than that of uncoated heat exchanger. Energy savings of approximately 41% were achieved in FH7 coated compared to uncoated heat exchangers. It has been emphasized that heat transfer in GPHE systems should be evaluated together with pressure drops and local losses. It was found that the use of hydrophobic surface coating on plates in heat exchangers will contribute to the development of heat exchanger designs, reducing pump costs, and energy consumption.