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Open Access Research Article Issue
Influence of high-temperature oxidation of SiC powders on curing properties of SiC slurry for digital light processing
Journal of Advanced Ceramics 2023, 12 (1): 169-181
Published: 07 December 2022
Downloads:533

Fabrication of silicon carbide (SiC) ceramics by digital light processing (DLP) technology is difficult owing to high refractive index and high ultraviolet (UV) absorptivity of SiC powders. The surface of the SiC powders can be coated with silicon oxide (SiO2) with low refractive index and low UV absorptivity via high-temperature oxidation, reducing the loss of UV energy in the DLP process and realizing the DLP preparation of the SiC ceramics. However, it is necessary to explore a high-temperature modification process to obtain a better modification effect of the SiC powders. Therefore, the high-temperature modification behavior of the SiC powders is thoroughly investigated in this paper. The results show that nano-scale oxide film is formed on the surface of the SiC powders by short-time high-temperature oxidation, effectively reducing the UV absorptivity and the surface refractive index (nʹ) of the SiC powders. When the oxidation temperature is 1300 ℃, compared with that of unoxidized SiC powders, the UV absorptivity of oxidized SiC powders decreases from 0.5065 to 0.4654, and a curing depth of SiC slurry increases from 22±4 to 59±4 μm. Finally, SiC green bodies are successfully prepared by the DLP with the the oxidized powders, and flexural strength of SiC sintered parts reaches 47.9±2.3 MPa after 3 h of atmospheric sintering at 2000 ℃ without any sintering aid.

Open Access Research Article Issue
Preparation and properties of T-ZnOw enhanced BCP scaffolds with double-layer structure by digital light processing
Journal of Advanced Ceramics 2022, 11 (4): 570-581
Published: 03 March 2022
Downloads:220

Bone scaffolds require both good bioactivity and mechanical properties to keep shape and promote bone repair. In this work, T-ZnOw enhanced biphasic calcium phosphate (BCP) scaffolds with triply periodic minimal surface (TPMS)-based double-layer porous structure were fabricated by digital light processing (DLP) with high precision. Property of suspension was first discussed to obtain better printing quality. After sintering, T-ZnOw reacts with β-tricalcium phosphate (β-TCP) to form Ca19Zn2(PO4)14, and inhibits the phase transition to α-TCP. With the content of T-ZnOw increasing from 0 to 2 wt%, the flexural strength increases from 40.9 to 68.5 MPa because the four-needle whiskers can disperse stress, and have the effect of pulling out as well as fracture toughening. However, excessive whiskers will reduce the cure depth, and cause more printing defects, thus reducing the mechanical strength. Besides, T-ZnOw accelerates the deposition of apatite, and the sample with 2 wt% T-ZnOw shows the fastest mineralization rate. The good biocompatibility has been proved by cell proliferation test. Results confirmed that doping T-ZnOw can improve the mechanical strength of BCP scaffolds, and keep good biological property, which provides a new strategy for better bone repair.

Open Access Research Article Issue
Influence of Al2O3 content on mechanical properties of silica-based ceramic cores prepared by stereolithography
Journal of Advanced Ceramics 2021, 10 (6): 1381-1388
Published: 28 September 2021
Downloads:190

Silica ceramic cores have played an important part in the manufacture of hollow blades due to their excellent chemical stability and moderate high-temperature mechanical properties. In this study, silica-based ceramics were prepared with Al2O3 addition by stereolithography, and the influence of Al2O3 content on mechanical properties of the silica-based ceramics was investigated. The Al2O3 in silica-based ceramics can improve the mechanical properties by playing a role as a seed for the crystallization of fused silica into cristobalite. As a result, with the increase of Al2O3 content, the linear shrinkage of the silica-based ceramics first decreased and then increased, while the room-temperature flexural strength and the high-temperature flexural strength first increased and then decreased. As the Al2O3 content increased to 1.0 vol%, the linear shrinkage was reduced to 1.64% because of the blocked viscous flow caused by Al2O3. Meanwhile, the room-temperature flexural strength and the high-temperature flexural strength were improved to 20.38 and 21.43 MPa with 1.0 vol% Al2O3, respectively, due to the increased α-cristobalite and β-cristobalite content. Therefore, using the optimal content of Al2O3 in silica-based ceramics can provide excellent mechanical properties, which are suitable for the application of ceramic cores in the manufacturing of hollow blades.

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