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中南大学学报(英文版)

Journal of Central South University

Vol. 28    No. 4    April 2021

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Densification mechanism of stereolithographical dense Si3N4 ceramics with CeO2 as sintering additive by field assisted sintering
RAO Wei-dong(饶为栋)1, 2, LIU Yao(刘耀)1, 3, CHENG Li-jing(程立金)4, LIU Shao-jun(刘绍军)1, 2

1. State Key Laboratory for Powder Metallurgy, Central South University, Changsha 410083, China;
2. Shenzhen Research Institute, Central South University, Shenzhen 518007, China;
3. College of Mechanical and Electronic Engineering, Pingxiang University, Pingxiang 337000, China;
4. School of Mechanical Engineering, Hebei University of Technology, Tianjin 300130, China

Abstract:Combining sintering additive with field assisted sintering, stereolithographical dense Si3N4 ceramics was successfully fabricated. Owing to a large amount of polymer during the stereolithography, the green parts have the characteristics of low powder loading and high porosity. Adjusting the process parameters such as sintering temperature and soaking time can effectively improve the density of the specimens. The stress exponent n of all specimens is in a range of 1 and 2, which is derived from a modified sintering kinetics model. The apparent activation energy Qd of stereolithographic Si3N4 ceramics sintered with applied pressures of 30 MPa, 40 MPa, and 50 MPa is 384.75, 276.61 and 193.95 kJ/mol, respectively, suggesting that the densification dynamic process is strengthened by raising applied pressure. The grain boundary slipping plays a dominating role in the densification of stereolithographic Si3N4 ceramics. The Vickers hardness and fracture toughness of stereolithographic Si3N4 ceramics are HV10/10 (1347.9±2.4) and (6.57±0.07) MPa·m1/2, respectively.

 

Key words: stereolithography; silicon nitride ceramics; sintering mechanism; densification; field assisted sintering

中南大学学报(自然科学版)
  ISSN 1672-7207
CN 43-1426/N
ZDXZAC
中南大学学报(英文版)
  ISSN 2095-2899
CN 43-1516/TB
JCSTFT
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