On November 16, 2021, researchers from Shenzhen University and National Taipei Polytechnical University published a study titled Mechanicalreinforcement of 3D Printed Cordierite-ZirconiaComposites in CeramicsInternational, reporting that the research focused on the preparation of cordierite-zirconia composite ceramic slurries for photopolymerization 3D printingand to study the effect of the addition of nano-zirconia particles on the mechanical properties of iolite samples prepared after high-temperature sintering. The strengthening mechanism of such samples, especially the toughening mechanism, was also studied.
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About the study
In this study, a submicron cordierite-zirconia composite ceramic slurry was studied, and composite ceramic slurries containing different zirconia contents were prepared. We directly designed and fabricated standard flexural strength and fracture toughness test samples using stereolithography 3D printing, and studied the mechanical enhancement effects with different sintering schemes. The physical composition and microstructure of the samples were characterized. After the addition of 2wt% and 6wt% zirconia, the bending strength and fracture toughness of the composite reached the maximum, which were 136MPa and 1., respectively8mpam, which is 44% and 66% higher than pure iolite, respectively. Through microstructure analysis, we further explained the strengthening and toughening mechanism of the composites. This study provides an alternative, straightforward design and manufacturing method for the mechanical testing and reinforcement of ceramic composite parts based on 3D printing technology.
Figure 1: Grain size distribution of iolite and zirconia.
Figure 2 X-ray diffraction pattern: (a) ZRO, (b) iolite.
Figure 3: Debinding and sintering curves of the green body sample.
Figure 4: Schematic diagram of the standard sample size and test method of the SEVNB method.
Fig. 5 The viscosity of the slurry with different zirconia contents varies with the shear rate.
Figure 6 X-ray diffraction pattern.
Figure 7: Effect of zirconia addition and sintering temperature on density (a) bulk density vs. (b) relative density, (c) relative density vs. different sintering temperatures.
Figure 8 SEM secondary electron imaging: (a) ZC0 powder, (B) ZC10 powder, (C) sintered part surface, (D) ZC0 polished surface, (E) ZC6 polished surface.
Figure 9: Relative density vsHold time and heating rate.
Fig. 10: Flexural strength as a function of heating rate and holding time.
Figure 11 Flexural strength as a function of zirconia content and sintering temperature: (a) zirconia content, (b) sintering temperature (for ZC6).
Figure 12 Fracture toughness vs. zirconia content and sintering temperature: (a) zirconia content, (b) sintering temperature (for zc6).
Figure 13(a)-(b) grain pull-out, (c)-(d) transgranular fracture and intergranular fracture.
Conclusions of the study
In the experiment, iolite-zirconia ceramic composite specimens were successfully designed and prepared by 3D printing technology based on stereolithography photopolymerization, and were sintered at high temperature. It is found that with the increase of zirconia content, the bulk density of composite materials increases, but when the zirconia content exceeds 8%, it will lead to porosity and cracks, and the bulk density decreases. The optimal heat treatment scheme was 6 min heating rate and 2 h holding time. With the increase of zirconia content, the flexural strength of the composite material increases, but the fracture toughness increases first and then decreases. With the increase of sintering temperature, the flexural strength and fracture toughness of the specimen increase gradually with the increase of zirconia content, printing parameters, heating rate and holding time. This study provides a method for manufacturing ceramic composite parts based on 3D printing technology.