Photocuring 3D Printing of Green Zirconia (ZrO₂)Ceramic Jewelry Material

Coloured zirconia (ZrO₂) ceramics have been widely used in the field of decorative materials and artwork because of their rich colour, metallic luster and excellent biocompatibility. Limited by the high strength and high hardness of zirconia ceramics, complex structure ceramic jewelry has high mold requirements, high cost and long cycle, which is not conducive to personalized customization. Laser stereo lithography apparatus (SLA), as a high-precision 3D printing technology without mold, has great potential in the manufacture of personalized ceramic jewelry with complex structural designs. However, this technology still has many challenges in printing high absorbance and high refractive index colour zirconia materials, mainly due to the ultraviolet light absorption of dark zirconia and light scattering caused by high refractive index, resulting in low curing layer thickness, easy layering and even difficult to form. In this study, based on SLA technology, green zirconia was taken as the research object, and low refractive index silica was introduced into green zirconia photocurable ceramic slurry as the ultraviolet light conduction medium, so as to reduce the difference of refractive index between solid and liquid interface of ceramic slurry, reduce the scattering and enhance the ultraviolet light transmission. Through the analysis of rheological mechanics, photocuring dynamics, phase structure, colour mechanism and mechanical properties, the printing forming process and degrease sintering process were optimized. Finally, it was determined that the green zirconia mixed with 15 vol.% silicon dioxide had better colour and mechanical properties. In summary, by adding 15 vol.% silica into the green zirconia ceramic slurry and sintering at 1 450 ℃, the complex structure ceramic jewelry with full colour and good mechanical properties can be prepared, which meets the aesthetic requirements and practical needs of green zirconia ceramic jewelry in the wearing process, and provides a new idea for the 3D printing of colored zirconia ceramics.