Evolution of the microstructure and mechanical properties of stereolithography formed alumina cores sintered in vacuum

Li, He; Liu, Yongsheng; Liu, Yansong; Zeng, Qingfeng; Wang, Jing; Hu, Kehui; Lu, Zongqing; Liang, Jingjing

doi:10.1016/j.jeurceramsoc.2019.11.047

Cited by 80 publications

(26 citation statements)

References 39 publications

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“…The printed green bodies were debinded and sintered in a muffle furnace (Hefei Ke Jing Materials Technology). The debinding temperature was 550°C with a holding time of 2 h, and the sintering temperature was 1500°C with a holding time of 2 h. 32 The heating rate was 2°C/min below 200°C, 1°C/min in the range of 200-550°C, and 5°C/min above 550°C.…”

Section: Debinding and Sinteringmentioning

confidence: 99%

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Effect of zirconia content and particle size on the properties of 3D‐printed alumina‐based ceramic cores

Zeng

2021

J. Am. Ceram. Soc.

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Ceramics usually have high hardness which is difficult to achieve, especially for complex parts with fine structures. [1][2][3][4] Considering the requirements of ceramic cores with rather intricate structures and requiring high precision, it is essential to develop fast, low cost, and high-precision ceramic-forming techniques. 5,6 Ceramic cores are applied in the form of internal passages for high-temperature hollow blades, a key factor to determine the quality of hollow blades. 7 Traditional preparation of ceramic cores is not only time consuming but also expensive, thus hindering the development of aircraft engines. 8 Fortunately, the emergence of 3D printing technology has changed the traditional production. In this method, parts are fabricated based on a layer-by-layer forming mode, significantly saving the raw materials. 9 Among various 3D printing technologies, printed parts obtained using stereolithography technique have the highest accuracy. 10 Thus, stereolithography-based 3D printing technology provides the possibility to fabricate ceramics parts in a highly efficient manner. [11][12][13][14] Alumina-based ceramic cores could resist a high operating temperature of 1520-1875°C and exhibit excellent high-temperature stability, exhibiting obvious advantages compared to the currently most used silica-based ceramic cores. 15,16 However, the binding force between alumina grains is weak when the sintering temperature is relatively low; therefore, second-phase zirconia is added to the alumina-based ceramic cores to guarantee good connections between the ceramic grains. [17][18][19] Several studies have focused on alumina-zirconia composite ceramics. Zhu et al. 20 studied the ballistic impact performance of nanocrystalline zirconia-toughened alumina (nZTA) and alumina ceramics; the fracture toughness of nZTA was found to be about 1.3 times than that of alumina, indicating that the toughness of alumina ceramics increased by adding zirconia. To lower the manufacturing costs and development time for complex parts, Pappas et al. 21 found that

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Section: Debinding and Sinteringmentioning

confidence: 99%

“…The application of ceramic cores requires a flexural strength of greater than 20 MPa and an open porosity of higher than 20%. [29][30][31][32] Because the high flexural strength of ceramics usually indicates a high bulk density, it leads to a low open porosity. At the same time, the high open porosity of ceramics generally leads to a low flexural strength.…”

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confidence: 99%

Effect of zirconia content and particle size on the properties of 3D‐printed alumina‐based ceramic cores

Zeng

2021

J. Am. Ceram. Soc.

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“…Schmidt et al [20] proposed dense and crack-free, highly complex porous mullite ceramics using stereolithography by firing a mixture of photosensitive polysiloxane and alumina powder. Li et al [21,22] discussed the effects of the sintering process on the microstructure and mechanical properties initially. They produced Al2O3 samples with a flexural strength of 33.7 MPa and open porosity of 37.9 % using stereolithography based additive manufacturing.…”

Section: Introductionmentioning

confidence: 99%

The Effect of Particle Distribution to the Sintering Properties of Al2o3 Ceramic Formed by Stereolithography

Qian¹,

Hu²,

Wang³

et al. 2021

Preprint

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This work studied the effect of particle size gradation on the structure and sintering properties of alumina ceramics manufactured by stereolithography after sintering, including room temperature flexural strength, sintering shrinkage, porosity and microstructure morphology. Seven different particle size gradations from coarse to fine were studied, and each particle size gradation was coarse particles: fine particles=6:4. With the increase of the sintering temperature, the degree of sintering and the bonding strength of the interface increased, the shrinkage in all directions, and the bending strength and the closed porosity increased, the open porosity decreased. For the same sintering temperature, the flexural strength and shrinkage in all directions decreased and the open porosity increased with the increase of particle size. The ratio of the height (4mm) shrinkage of each particle size to the length (50mm) shrinkage is about 1.5 times. Due to the presence of the lateral edge resin layer, the width shrinkage of the coarse particles was different from the length shrinkage but closer to the height shrinkage. The width shrinkage gradually approached the length shrinkage as the particle size decreased. When the gradation ratio is the same, and the particle size was ten times different (30μm/5μm, 3μm/0.5μm; 20μm/3μm, 2μm/0.3μm), there was a big difference. When the sintering temperature was above 1500℃, the differences of sintering properties of the comparison groups are 2~10 times. Considering the alumina-based ceramic core, 20/3 has been evaluated comprehensively. It maintains excellent flexural strength and porosity under the condition of slight shrinkage.

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“…Because the ceramic cores should be removed, its open porosity should be greater than 30%. During the preparation of hollow turbine blades, the ceramic cores should be able to withstand a certain amount of impact; therefore, its flexural strength should be greater than 20 MPa [14][15][16][17][18][19].…”

Section: Introduction mentioning

confidence: 99%

Effect of sintering temperature in argon atmosphere on microstructure and properties of 3D printed alumina ceramic cores

et al. 2020

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Alumina ceramics with different sintering temperatures in argon atmosphere were obtained using stereolithography-based 3D printing. The effects of sintering temperature on microstructure and physical and mechanical properties were investigated. The results show that the average particle size, shrinkage, bulk density, crystallite size, flexural strength, Vickers hardness, and nanoindentation hardness increased with the increase in sintering temperature, whereas the open porosity decreased with increasing sintering temperature. No change was observed in phase composition, chemical bond, atomic ratio, and surface roughness. For the sintered samples, the shrinkage in Z direction is much greater than that in X or Y direction. The optimum sintering temperature in argon atmosphere is 1350 ℃ with a shrinkage of 3.0%, 3.2%, and 5.5% in X, Y, and Z directions, respectively, flexural strength of 26.7 MPa, Vickers hardness of 198.5 HV, nanoindentation hardness of 33.1 GPa, bulk density of 2.5 g/cm 3 , and open porosity of 33.8%. The optimum sintering temperature was 70 ℃ higher than that sintering in air atmosphere when achieved the similar properties.

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Evolution of the microstructure and mechanical properties of stereolithography formed alumina cores sintered in vacuum

Cited by 80 publications

References 39 publications

Effect of zirconia content and particle size on the properties of 3D‐printed alumina‐based ceramic cores

Effect of zirconia content and particle size on the properties of 3D‐printed alumina‐based ceramic cores

The Effect of Particle Distribution to the Sintering Properties of Al2o3 Ceramic Formed by Stereolithography

Effect of sintering temperature in argon atmosphere on microstructure and properties of 3D printed alumina ceramic cores

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