Evaluation of Mechanical Properties of Self-cured, Heat-cured, and Photosensitive 3D Printing Resins After the Addition of Silica Nanoparticles

Sun, 30 Jun 2024 00:00:00 +0000

This study evaluated investigate the addition of silica nanoparticles in autopolymerizable resin and into liquid resin for 3D printing and compare them with CAD-CAM blocks and thermopolymerizable resin, regarding flexural strength and surface roughness. Eight groups (n=12) were created according to the types of materials: autopolymerizable resin (G1-G4), photosensitive resin for 3D printing (G5-G6), PMMA block (G7) and thermopolymerizable resin (G8). Functionalized silica nanoparticles (0.5-1.5 wt%) were added in groups G2-G4 and G6. Mechanical flexural strength, surface roughness and morphological analysis were carried out to evaluate the properties of the samples. One-way ANOVA, followed by Tukey's post-hoc test, was used to evaluate the data. The average surface roughness was higher in group G7 and lower in the G8 group, with a statistical difference (p < 0.001). The G8 and G1-G4 showed no significant difference in surface roughness. The G5 and G6 presented surface roughness higher than that recommended by Borchers and Bollen (Ra=0.2 µm). The incorporation of nanoparticles into self-polymerizing acrylic resins negatively affected the mechanical properties of the material, reducing flexural strength. The G5 and G6 demonstrated the lowest flexural strength (p<0.001), presenting values lower than those recommended by ISO (σ >60 MPa) regardless of the incorporation or not of silica nanoparticles. The G7 presented the highest flexural strength value followed by the G8. Within the limits of this study, it may be concluded that the addition of silica nanoparticles did not improve the flexural strength the G6 and also affected negatively the mechanical properties of self-polymerizing acrylic resins.

Evolution of Microstructure During Stress Relieving Heat Treatment of 1S Aluminium

Gargi Choudhuri — Sun, 30 Jun 2024 00:00:00 +0000

Aluminium and its alloys are extensively used in nuclear research reactors due to its low neutron absorption coefficient, good heat transfer properties, excellent corrosion and oxidation resistance in air and water environment combined with desirable mechanical properties along with considerable radiation stability. The thin walled tubes are normally manufactured through port hole die extrusion route and used in 'O' tempered condition. The thin tubes in 'O' tempered condition are undergone canning operation which may alter the microstructural features to some extent which may affect mechanical properties. The paper describes the extent to which microstructural and subsequently mechanical properties are altered due to the simulated canning process and further requirements of stress relieving heat treatment to restore the microstructural features and mechanical properties. The following studies are carried out with 1S aluminum tube in 'O' tempered state, simulated canning condition and stress relieved at different temperature, - hardness measurement, X ray line profile analysis for dislocation density measurement, tensile properties measurement using ring tensile testing, electron back scattered diffraction (EBSD) analysis for recrystallization fraction determination and changes in texture components. It is found that the canning operation changes dislocation density, micro-strain, coherent domain size which are well reflected in hardness and ring tensile testing. Subsequent stress relieving at 350°C for 2 hrs. leads to improvement of mechanical properties appreciably.

Journal of Materials and Applications

Evaluation of Mechanical Properties of Self-cured, Heat-cured, and Photosensitive 3D Printing Resins After the Addition of Silica Nanoparticles

Evolution of Microstructure During Stress Relieving Heat Treatment of 1S Aluminium