Electrospun Chitosan/Silver Doped-Hydroxyapatite Nano-Fibers on Thermal Conductivity Modified Si3N4 Ceramics with Different Sintering Cooling Rate

Dental implants are exposed to cycle loadings and thermal changes. The thermal properties of the materials in dentistry are important in terms of the biological changes that these materials will create in living tissues. The normal temperature of the oral cavity varies between 32-37℃, while eating, it can vary between 0-80℃ with hot-cold foods which led to the trauma and implant deteriorations. Si3N4 ceramic is a good candidate to solve these problems due to its inertness, high fracture toughness, strength, high thermal shock resistance and low density. Also, the surface modification of Si3N4 is important to enhance the interaction between the implant and bone. In recent years, biodegradable organic biomaterials as CTs (CTs) and silver doped hydroxyapatite (HAPs) combinations have a great attention to improve the Si3N4 effectiveness. In this study, MgO, SiO2, and Y2O3 included substrates were fabricated for fast and slow cooling rate during sintering in dental applications. CTs/HAPs fibers were coated with the electrospinning method to develop a modified Si3N4 substrate. The crystal structure, microstructure and thermal diffusivity measurement of the substrates and spun surfaces were characterized with XRD, SEM and Laser Flash Method. From the results, the higher density (3.25g/cm3) and thermal conductivity (46.35W/mK) for Si3N4 were observed for the fast cooling process during sintering compared with the slow cooling process (3.22g/cm3 and 44.60 W/mK). The hardness and strength of the fast cooled substrate were measured as 1350 HV and 1800 MPa which are greater than the slowly cooled samples (1190 HV, 1670 MPa). CTs /HAPs fibers are homogeneously deposited with electrospinning on the surface of the fast cooled Si3N4 substrate to develop the surface functionality. This functionalized substrate can be a candidate in dental applications.