Laser Stereolithography for Zirconia Ceramic Fabrication and Its Debinding and Sintering Process

doi:10.15541/jim20210569

Abstract

Abstract:

Due to good mechanical properties, biocompatibility and corrosion resistance, zirconia ceramic has been widely used in dental repairing. However, the present technologies for zirconia ceramic fabrication based on stereolithography have some drawbacks, such as low fabrication accuracy, low debinding efficiency, high shrinkage, and shrinkage anisotropy. In order to solve these problems, a kind of hybrid resin was prepared by using different monomers with different functionalities, and then zirconia ceramic slurry with solid content of 55% (volume percentage) was prepared by using this hybrid resin, which dispersed organic matter pyrolysis interva, promoting debinding efficiency and avoiding crack. Besides, effect of laser power and scanning speed to the curing unit shape were studied, the optimum laser power of 670 mW and scanning speed of 2500 mm/s were selected to meet requirments of fabrication accuracy and efficiency. In addition, effects of scanning line space and scanning line width compensation to horizontal dimension accuracy and slicing thickness to the stacking dimension accuracy were studied. Optimum process scanning line space of 0.08 mm, scanning line width compensation of 0.10 mm, and slicing thickness of 0.03 mm were determined. Meanwhile, the green part was debinded in nitrogen atmosphere, which reduced pyrolysis rate of organic matter, performed a further improvement of debinding efficiency and green part cracking. At last, the debinded part was sintered. The plane and stacking direction shrinkages of the sintered part are (18.26±0.10)% and (19.20±0.13)%, respectively. All these results demonstrated that the shrinkage is reduced and the shrinkage anisotropy is reduced obviously, which provides basis for application in dental repairing.

Key words: zirconia ceramic, stereolithography, accuracy, debinding, sintering

CLC Number:

TQ174

WANG Yaning, ZHANG Yuqi, SONG Suocheng, CHEN Ruomeng, LIU Yaxiong, DUAN Yugang. Laser Stereolithography for Zirconia Ceramic Fabrication and Its Debinding and Sintering Process[J]. Journal of Inorganic Materials, 2022, 37(3): 303-309.

Figures/Tables 7

Table 1 Component proportion of hybrid resin

Component	Mass percentage/%
Bifunctional monomer (HDDA, Curease, China)	38.0
Trifunctional monomer (TMPTA, Curease, China)	28.5
Hexafunctional monomer (DPHA, Curease, China)	28.5
Oligomer (NeoRadU Curease, China)	5.0

Table 2 Component proportion of ceramic slurry

Component	Proportion
Zirconia powder	Volume ratio to resin: 11 : 9
Resin	Volume ratio to ceramic: 9 : 11
Photoinitiator (819, Curease, China)	0.3% (mass percentage) of resin
Dispersant (TEGO685, TEG, China)	2% (mass percentage) of ceramic
Defoamer (TEGO900, TEG, China)	1% (mass percentage) of resin

Fig. 1 Section of ceramic curing unit

Fig. 2 Curing unit width (a) and thickness (b) vs. laser power, and curing unit width (c) and thickness (d) vs. scanning speed

Fig. 3 Horizontal dimension error vs. scanning line space (a), schematic diagram of scanning strategy (b), horizontal dimension error vs. scanning line width compensation (c), and stacking dimension error vs. slicing thickness (d)

Fig. 4 TG and DTG curves of different resin in different atmosphere (a), debinding curve of green body (b), pictures of strip parts after debinding in nitrogen (c) and air (d) atmospheres, and SEM images of green part (e) and debinded part (f) Colorful figures are availuable on the website

Fig. 5 Sintering curve (a), pictures of green parts of cube (b) and three units dental bridge (c), sintered parts of cube (d) and three units dental bridge (e), and SEM image of sintered part (f)

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