3D printing of dense structural ceramic microcomponents with low cost: Tailoring the sintering kinetics and the microstructure evolution

Abstract

In this study, we have successfully developed a unique 3D printing approach based on mask-image-projection stereolithography (MIP-SL) to fabricate structural ceramics microcomponents with low cost and high efficiency. Ultra-dense submicron crystalline ceramics without fierce grain growth could be obtained via tailoring the sintering kinetics. The ZrO 2 ceramic microcomponents reached the highest relative density (RD) of 99.7% with the average grain size of 0.52 μm upon sintering at 1550°C while the Al 2 O 3 ceramic microcomponents reached its highest RD of 98.31% with the average grain size of 2.6 μm upon sintering at 1600°C.Oxide ceramics microcomponents of fully flexible design can be produced easily without visible defects via the method developed in this study, which demonstrates significant potential in the applications of microelectromechanical systems, micro-optical electronics systems and micro-opto-electro-mechanical systems. The method developed in this study has addressed the problem successfully by healing the interlayer interface defects in densification process via the sintering kinetic window and microstructure evolution. The current work provides a promising opportunity to fabricate structural ceramic microcomponents with complex shape, high precision, and high surface smoothness. K E Y W O R D S

Sintering Process Optimization for 3YSZ Ceramic 3D-Printed Objects Manufactured by Stereolithography

“…The relative density and grain size of the green body and sintered body of the 3YSZ 3D-printed objects were analyzed according to the sintering temperature, as shown in Figure 5 b. A three-step sintering mechanism has been reported based on sintering theory [ 16 ]. For 3YSZ, the first stage is carried out at approximately 1150 °C.…”

Micro-fabrication of ceramics: Additive manufacturing and conventional technologies

“…Liu et al [86] developed a micro-stereolithography approach to fabricate alumina and zirconia microcomponents with high density and controlled grain size. The authors mixed the ceramic powder with photosensitive polymers using powder milling and ultra-sonication to prepare homogenised powder mix suitable for a stereolithography 3D printer.…”

“…Fig. 5 Alumina and zirconia ceramic micro-components fabricated using stereo-lithography: (B-E) cellular structures with different pore size and helical structure, (F, G) different size micro-gears, (H) turbine micro-rotor, (I) columnar array with pillar diameter of 100-200 μm.Reproduced with permission from Ref [86],. © The American Ceramic Society 2018.…”

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

“…The introduction of Y2O3 enables the Al2O3 matrix grain size to be refined, due to the pinning effect of Y3Al5O12 precipitations [33,59]. [24]. The microstructure refinement is often expected to fabricate Al2O3 ceramic with higher strength according to the Hall-Petch relationship [61].…”

“…For instance, as presented in Refs. [20] and [24], the grain sizes of the Al2O3 ceramics fabricated by stereolithography were 24 and 12 times larger than the average particle sizes of the feedstock Al2O3 powders, respectively; In addition, a satisfactory microstructure uniformity of the Al2O3 ceramics prepared by SLAstereolithography can hardly be obtained even if the Al2O3 samples were sintered at a relative low temperature (1550 °C) [27]. The abnormal grain growth and non-uniform microstructure can result in lower flexural strength and reliability of ceramics [28,29], which will further shorten service lifetime of ceramic substrates and heat sinks [30] and thus restrict their application in electronics.…”