Microstructure refinement-homogenization and flexural strength improvement of Al2O3 ceramics fabricated by DLP-stereolithography integrated with chemical precipitation coating process

Abstract

In this study, the chemical precipitation coating (CP) process was creatively integrated with DLP-stereolithography based 3D printing for refining and homogenizing the microstructure of 3D printed Al2O3 ceramic. Based on this novel approach, Al2O3 powder was coated with a homogeneous layer of amorphous Y2O3, with the coated Al2O3 powder found to make the microstructure of 3D printed Al2O3 ceramic more uniform and refined, as compared with the conventional mechanical mixing (MM) of Al2O3 and Y2O3 powders. The grain size of Al2O3 in Sample CP is 64.44% and 51.43% lower than those in the monolithic Al2O3 ceramic and Sample MM, respectively. Sample CP has the highest flexural strength of 455.37±32.17 MPa, which is 14.85% and 25.45% higher than those of Samples MM and AL, respectively; also Sample CP has the highest Weibull modulus of 16.88 among the three kinds of samples. Moreover, the fine grained Sample CP has a close thermal conductivity to the coarse grained Sample MM because of the changes in morphology of Y3Al5O12 phase from semi-connected (Sample MM) to isolated (Sample CP). Finally, specially designed fin-type Al2O3 ceramic heat sinks were successfully fabricated via the novel integrated process, which has been proven to be an effective method for fabricating complex-shaped Al2O3 ceramic components with enhanced flexural strength and reliability.

Digital light processing‐based additive manufacturing of orientation‐controlled Al2O3 ceramics with improved damage tolerance

“…The lowest fracture toughness of 3.8 ± 0.4 MPa·m 1/2 is found for PL‐20. Considering the empirical suggestion on the strength of sintered ceramics, 43 there is a strong dependence of the strength on the density of ceramics. Interestingly, despite the steady drop in the ceramic density with platelets added, the strength and toughness display a tendency to increase and then decrease.…”

Micromechanical characterization of microwave dielectric ceramic BaO–Sm 2O 3–5TiO 2 by indentation and scratch methods

“…Gaussian distribution [7]. Since Weibull distribution has been widely used to assess the statistical variation of strength [147] or the measured cracking length of brittle materials (e.g., ceramics [148,149] and glasses [150]), and values of fracture toughness obtained by 40 measurements of 2c under each load were analyzed by the well-known two-parameter Weibull distribution equation [149,151]:…”

Additive manufacturing of silicon nitride ceramics: A review of advances and perspectives

“…Therefore, the emergence of AM technologies provides an innovative technological approach for the fabrication of complex-shaped ceramics. Currently, typical oxide ceramics (such as Al 2 O 3 , 26,27 ZrO 2 , [28][29][30] etc. ), precursor-derived ceramics (such as SiOC, 31,32 SiCN, 33,34 etc.…”