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The aim is to investigate the impact of phase contents on mechanical properties, translucency, and aging stability of additively manufactured yttria partially stabilized zirconia ceramics. For that purpose, we evaluated two PSZ materials. The first type was prepared utilizing commercially available 5 mol% yttria-stabilized zirconia(5Y-PSZ), while the second type, denoted as 3Y+8Y-PSZ ceramics, was fabricated by blending 3 mol% and 8 mol% yttria-stabilized zirconia powders. Compared to 5Y-PSZ (39.90 wt% tetragonal phases and c / a 2 = 1.0141), 3Y+8Y-PSZ is characterized by a greater abundance of tetragonal phases (47.68 wt%), which display higher tetragonality (c / a 2 = 1.0165) and lower yttrium oxide content (2.25mol%). As a result, the 3Y+8Y-PSZ demonstrates elevated strength (816.52 MPa) and toughness (4.32 MPa m1/2), accompanied by reduced translucency(CR:0.47) and it exhibits greater susceptibility to aging. The phase contents, yttrium oxide content, and lattice parameters in the tetragonal phase play a crucial role in determining the mechanical properties, translucency, and aging stability of PSZ ceramics. • Comparison between two PSZ ceramics with different phase contents and structures. • Strength of 5Y-PSZ prepared via SLA is comparable to traditionally prepared ones. • EDS shows differences in the distribution of yttrium in the phases of two PSZs. • The two PSZs differ in strength, toughness, translucency and aging resistance. [ABSTRACT FROM AUTHOR]

Architectural and functional structures composed of lunar regolith-simulant CLRS-2 were fabricated via digital light processing and sintered at 1100 °C and 1150 °C under an air or argon atmosphere. This work is to investigate effects of atmosphere and temperature on mechanical properties, microstructure, and chemical composition of lunar regolith products. Samples sintered at 1150 °C in air underwent the highest sintering shrinkage and showed the best mechanical properties, likely due to the formation of glassy phase and dense structure following sintering. Conversely, argon-sintered samples exhibited lower density resulting from the lack of glassy phase. Phase analysis revealed varying chemical composition and therefore different underlying reaction mechanisms under two sintering atmospheres, indicating that sintering atmosphere significantly influences the microstructure and macroscopic properties of lunar regolith products. [ABSTRACT FROM AUTHOR]

The purpose of this study was to obtain dental ceramic materials with excellent mechanical properties and high resistance to low temperature degradation (LTD) via stereolithography (SLA) in combination with microwave sintering (MWS). The results have shown that the unaged MWS-1425 °C 3Y-TZP ceramics with uniform microstructure have high density up to 99.04% and excellent mechanical properties (Vickers hardness 14.07 GPa, fracture toughness 4.32 MPa m1/2, flexural strength 947.87 MPa). After 50 h of LTD, the m-phase content of MWS 3Y-TZP ceramics accounts for only 10.3%. In addition, the surface roughness increases by only 1.3 nm, the degraded depth is less than 5 μm, and the flexural strength exceeds 900 MPa. This exhibits the high resistance to LTD and excellent mechanical properties of dental 3Y-TZP ceramics can be obtained. [ABSTRACT FROM AUTHOR]

A study was conducted to explore the potential of 5 mol% yttria-partially stabilized zirconia (5Y-PSZ) ceramics for dental restorations, using stereolithography (SLA) printing technique. Four different solid loadings were established in the ceramic paste systems to study their effects on microstructure, mechanical properties, and translucency. The study examined the rheological behavior and photopolymerization performance of the ceramic pastes with varying solid loadings. Results showed that, an increase in powder concentration resulted in a decrease in cure depth (Cd) and penetration depth (Dp). A narrower pore size distribution was observed in the green bodies with a high solid loading, facilitating the achievement of final densification. The green and sintered densities were highest at 52 vol%, with values of 3.46 ± 0.01 g/cm3 and 6.01 ± 0.02 g/cm3, respectively. Additionally, all of the green strengths exceeded 30 MPa, with a maximum of 35.09 ± 2.02 MPa obtained at 44 vol%. The maximum flexural strength and minimum contrast ratio (CR) value of 746 ± 75 MPa and 0.40 ± 0.01 were achieved at 52 vol% after sintering. No significant differences were observed in the phase composition and hardness of the as-sintered ceramics. Though significant differences were observed in photopolymerization performance, four materials showed similar structural reliability considering Weibull modulus and characteristic strength. [ABSTRACT FROM AUTHOR]

In this article, polyamide 6 (PA6), maleic anhydride grafted ethylene-propylene-diene monomer (EPDM- g-MA), high-density polyethylene (HDPE) were simultaneously added into an internal mixer to melt-mixing for different periods. The relationship between morphology and rheological behaviors, crystallization, mechanical properties of PA6/EPDM- g-MA/HDPE blends were studied. The phase morphology observation revealed that PA6/EPDM- g-MA/HDPE (70/15/15 wt %) blend is constituted from PA6 matrix in which is dispersed core-shell droplets of HDPE core encapsulated by EPDM- g-MA phase and indicated that the mixing time played a crucial role on the evolution of the core-shell morphology. Rheological measurement manifested that the complex viscosity and storage modulus of ternary blends were notable higher than the pure polymer blends and binary blends which ascribed different phase morphology. Moreover, the maximum notched impact strength of PA6/EPDM- g-MA/HDPE blend was 80.7 KJ/m2 and this value was 10-11 times higher than that of pure PA6. Particularly, differential scanning calorimetry results indicated that the bulk crystallization temperature of HDPE (114.6°C) was partly weakened and a new crystallization peak appeared at a lower temperature of around 102.2°C as a result of co-crystal of HDPE and EPDM- g-MA. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 [ABSTRACT FROM AUTHOR]

Silicon nitride (Si 3 N 4) ceramics have been successfully manufactured using vat photopolymerization (VPP) technology. The formulated photocurable paste achieved a high solid loading (48 vol%) while maintaining low viscosity (3.2 Pa s at a shear rate of 30 s−1). Si 3 N 4 ceramics doped with Al 2 O 3 –Y 2 O 3 sintering aids were prepared using pressureless sintering at different temperatures (1650 °C, 1700 °C and 1750 °C) for 2 h. The resultant material exhibited a flexural strength of 613.3 ± 53.1 MPa, Vickers hardness of 12.6 ± 0.4 GPa, and a fracture toughness of 7.5 ± 0.3 MPa m1/2. X-ray diffraction (XRD) analysis has demonstrated a complete transformation from α-Si 3 N 4 to β-Si 3 N 4 at a sintering temperature of 1750 °C, where the resultant ceramic exhibited distinctive grain growth anisotropy. By investigating the shrinkage at different sintering temperatures, the sample at 1750 °C has a larger shrinkage in the Z-direction, which is also related to its anisotropic grain growth. Scanning electron microscopy (SEM) images have revealed the presence of elongated grains at a sintering temperature of 1750 °C. The combined effect of elongated grains and growth anisotropy serves to significantly enhance the overall mechanical properties of the material. This study advances current research on the preparation of high-performance Si 3 N 4 ceramics by combining VPP technology with pressureless sintering. [ABSTRACT FROM AUTHOR]

The current study describes the mechanical properties and translucency of 5 mol% yttria-partially stabilized zirconia (5Y-PSZ) prepared via stereolithography (SLA). A stable 5Y-PSZ ceramic paste with a maximum solid loading of 52 vol% is prepared for the SLA process, and the corresponding rheological model between viscosity and shear rate is analyzed. After sintering, all samples exhibited the same hardness and fracture toughness, approaching 12.65 GPa and 3.20 MPa m1/2, respectively. Also, the density and flexural strength reached their maximum values at 1550 °C, which were 5.95 g/cm3 and 685.6 MPa, respectively, while the contrast ratio (CR) reached its minimum value of 0.43 at 1500 °C. Moreover, failure origin and Weibull analysis are performed to evaluate the structural reliability of the ceramic components. It is observed that the yttrium content in large grains was higher than the small grains, indicating large grains consisted of the cubic phase. Herein, the stronger grain boundaries are caused by the higher segregation of yttrium at grain boundaries, altering fracture mode from the intergranular fracture to the mixed mode of trans - and intergranular fracture at 1550 °C. [ABSTRACT FROM AUTHOR]

In this study, iron(III) oxide (Fe 2 O 3)-doped zirconia (3Y-TZP) ceramics with desirable mechanical and color properties for dental restorations were fabricated by stereolithography-based additive manufacturing. Six zirconia ceramic paste specimens with high solid loading (58 vol%) and reasonably low viscosity were prepared according to doped content of Fe 2 O 3 (0–0.14 wt%). Zirconia ceramics were fabricated using commercial stereolithography three-dimensional printer and sintered at 1500 °C for 4 h to obtain final dense parts with a relative density of above 99%. Effects of Fe 2 O 3 doping on microstructure, mechanical properties, and color of 3Y-TZP ceramics were investigated. Results indicate that Fe 2 O 3 exhibited little effect on the shrinkage and density of colored ceramics compared to uncolored ceramics. Average grain size of 3Y-TZP ceramics sintered at 1500 °C increased with increasing content of Fe 2 O 3. X-ray diffraction analysis showed that tetragonal phase was dominant phase structure of white and colored 3Y-TZP ceramics, and monoclinic phase increased with increasing Fe 2 O 3 content. Compared to uncolored specimens, Fe 2 O 3 exhibited negative effects on three-point flexural strength (mean > 879.70 MPa), Vickers hardness (mean > 12.14 GPa), and indentation fracture toughness (mean > 4.23 MPa m1/2) of the colored specimens. With the increase in the content of Fe 2 O 3 from 0 to 0.14 wt%, L * (black–white index) value decreased from 83.39 to 79.54, a * (green–red index) value increased from −2.28 to −0.74, and b * (blue–yellow index) value increased from 1.15 to 17.94. Chromaticity (L * , a * , b *) fell within the range of natural tooth color, indicating that it is suitable for dental application because of its color compatibility with natural teeth. In addition, the transmittance slightly decreased with increasing Fe 2 O 3 content. Thus, Fe 2 O 3 -doped 3Y-TZP ceramics can be used as potential candidates for aesthetic dental restoration materials. [ABSTRACT FROM AUTHOR]

AlN ceramics were successfully fabricated through a joint process of digital light processing (DLP) 3D printing technology and heat treatment at 1780 °C∼1845 °C. DLP is an addictive manufacturing process, enabling the near net shape fabrication. The AlN grains in this work developed well and there were small amounts of grain-boundary phases at the three-grain junctions. The particle size of AlN became larger and the densification increased with increasing sintering temperature. The pores of AlN ceramics also decreased, which led to the increase of thermal conductivity and flexural strength. The optimal thermal conductivity and flexural strength of AlN ceramic reached 155 W/(m·K) and 265 ± 20 MPa when sintered at 1845 °C. [ABSTRACT FROM AUTHOR]

Partially stabilized zirconia (PSZ) moulds for aluminium casting were fabricated by stereolithographic additive manufacturing via digital light processing (DLP). Green parts were fabricated on DLP equipment using curable ceramic suspension. These suspensions were studied by performing photopolymerisable and rheological characterisations. Thermogravimetry (TGA) was used to analyse thermal stability of the suspension. Phase composition of sintered parts was determined by X-ray diffraction (XRD), while mechanical properties of green and sintered parts were studied by three-point bending testing. Flexural strength and Young's modulus of sintered parts were determined to be 803.7 ± 59 MPa and 203.4 ± 17 GPa, and these values decreased to 41.5 ± 3.9 MPa and 3.1 ± 0.3 GPa for green parts, respectively. Large pores were suggested to originate failure, with fracture mode being predominantly intergranular. Finally, sintered ceramic investment moulds were prepared by stereolithography and subsequently used for aluminium casting purposes. Dimensions of green parts before sintering were about 0.5% smaller than design values within the plane of layers, and approximately 0.5% larger than design values perpendicular to the layers. Sintering shrinkage was around 22% in both directions. Surface roughness of sintered moulds and aluminium casting materials were quantitatively determined by profilometry. [ABSTRACT FROM AUTHOR]