RESUMO
In this study, we have analysed the effects of a silane coupling agent on the volume fraction of zirconia for digital light processing (DLP)-based additive manufacturing processes. Zirconia suspension was prepared by the incorporation of silane-modified zirconia particles (experimental group) or untreated zirconia particles (control group). Furthermore, the control and experimental group were subdivided into three groups based on the volume fraction (52, 54, and 56 vol%) of zirconia particles. The disk-shaped zirconia samples were 3D (three-dimensional) printed using the DLP technique and their physical and mechanical properties were evaluated. The addition of a silane coupling agent to the zirconia samples was found to have influence of about 6% on the hardness and biaxial flexural strength. Moreover, the decrease in minute air gaps inside the zirconia layers significantly increased the material density (visualized from the microstructure analysis). Thus, from this study, it was established that the silane-modified zirconia particles had a positive effect on the physical properties of the zirconia parts.
RESUMO
45S5 bioactive glass (45S5) scaffolds were fabricated using a novel additive-manufacturing (AM) technology. A ceramic injection printer (CIP) was designed by combining injection molding and fused deposition modeling, for the fabrication of three-dimensional constructs of ceramic materials. A high fraction (50 vol%) of 45S5 powder was mixed with the thermoplastic polymer. The synthesized 45S5 composites were subjected to Brunauer-Emmett-Teller (BET) analysis, X-ray diffraction (XRD) analysis, and field-emission scanning electron microscopy (FE-SEM). The BET results of prepared 45S5 powder were confirmed to have a mean pore diameter of 11.402 nm, and specific surface area is 0.966 m²/g. The prepared 45S5/thermoplastic composite powder was subjected to Thermogravimetric/Differential thermal analysis (TG/DTA). The debinding process of polymer occurred at 192.5, 360.8, and 393 °C. The elastic modulus and ultimate stress of these scaffolds were measured to be 312.49±87.36 MPa and 21.83±6.67 MPa, respectively. The XRD results revealed the presence of Na6Ca3Si6O18 phases. The presence of Si, Ca, P, and Na was confirmed via energy-dispersive X-ray spectroscopy (EDS). The printed scaffold exhibited amorphous calcium phosphate (ACP) expression after immersion in simulated body fluid (SBF) and also it was observed that the intensity of the crystalline phase of 45S5 was decreased, as the immersion time increases. Bioactive glass composites with the high volume fraction can be able to construct 3D complex porous scaffolds using CIP.
RESUMO
OBJECTIVE: The objectives of the present study were: (1) to analyze the dispersion and optical properties of suspensions with various volume fractions of zirconia, and (2) to assess the influence of zirconia volume fraction on the microstructure and physical properties of products produced by the additive manufacturing and sintering process. METHODS: Zirconia specimens were fabricated by an additive manufacturing technique using a DLP (digital light processing) system. The zirconia suspensions were divided into six groups based on zirconia volume fraction within the range of 48-58vol%. RESULTS: The maximum volume fraction of zirconia in suspensions possible for printing was 58vol%. The cure depth of the zirconia suspensions decreased as the volume fraction increased. The cure depth was greater than 100µm after 15s photocuring in all groups. Geometrical overgrowth tended to increase gradually as the volume fraction of zirconia increased within the range of 28.55-36.94%. The 3-point bending strength of the specimens increased as the volume fraction of zirconia in the suspension increased, reaching a maximum value of 674.74±32.35MPa for a volume fraction of 58vol%. Cracks were observed on the surfaces of zirconia specimens and these cracks increased in number as zirconia volume fraction decreased. SIGNIFICANCE: In this experiment, the viscosity of zirconia suspensions sharply increased from a volume fraction of 54vol%. Because of the very high viscosity, 58vol% was the maximum volume fraction possible for additive manufacturing. After polymerization, all specimens showed some distortion due to geometrical overgrowth. The maximum 3-point bending strength was 674.74±32.35MPa for a volume fraction of 58vol%. But the maximum strength of sintered zirconia prepared by additive manufacturing is inferior to that of conventionally sintered zirconia.
Assuntos
Cerâmica , Zircônio , Teste de Materiais , Microscopia Eletrônica de Varredura , Propriedades de Superfície , SuspensõesRESUMO
The optical properties of zirconia photopolymer suspension for DLP (Digital Light Processing) were evaluated. The light source and intensity were set to 395 nm and 30 mW/cm². Experimental groups were divided into 48, 50, 52, 54, 56 and 58 vol% according to the zirconia volume fraction. The cure depth of all groups was at least 47.35 um when cured for 1 sec, which was higher than layer parameter values of the 3D printer. The geometrical overgrowth showed 28.55% at 48 vol% and 36.94% at 58 vol%. As the volume fraction of zirconia increased, the geometrical overgrowth increased and the cure depth reduced.
