Effect of doping SiC particles on cracks and pores of Al2O3–ZrO2 eutectic ceramics fabricated by directed laser deposition

• Published in: Journal of materials science Vol. 54; no. 13; pp. 9321 - 9330
• Main Authors: Wu, Dongjiang, Lu, Fan, Zhao, Dake, Ma, Guangyi, Li, Chaojiang, Ding, Jun, Niu, Fangyong
• Format: Journal Article
• Language: English
• Published: New York Springer US 01-07-2019; Springer Nature B.V
• Subjects: Aluminum oxide; Ceramics; Characterization and Evaluation of Materials; Chemistry and Materials Science; Classical Mechanics; Cracks; Creep strength; Crystallography and Scattering Methods; Doping; Energy dissipation; Eutectic reactions; High temperature; Interface reactions; Laser deposition; Materials Science; New technology; Oxidation resistance; Particulate composites; Polymer Sciences; Porosity; Silicon carbide; Solid Mechanics; Transgranular fracture; Zirconium dioxide
• ISSN: 0022-2461; 1573-4803
• DOI: 10.1007/s10853-019-03555-z

Melt growth Al
2
O
3
–ZrO
2
eutectic ceramic has excellent high-temperature strength, creep resistance, oxidation resistance and ultra-high-temperature microstructural stability, which is expected to become one of the ideal high-temperature structural materials. Directed laser deposition (DLD) is a new technology for fabrication of melt growth eutectic ceramics, which can rapidly fabricate net-shaped ceramics. Aiming at decreasing crack and pore defects in samples prepared by DLD, different proportions of SiC particles (SiCp) are doped into Al
2
O
3
–ZrO
2
. Results show that SiCp distributes uniformly in Al
2
O
3
–ZrO
2
eutectic ceramic matrix. Interfacial reaction occurs between SiCp and matrix. Two kinds of white phases rich in C, Si, Zr elements are formed around SiCp, and they are closely bonded with SiCp and matrix. The number and the maximum length of cracks in sample decrease obviously with the addition of SiCp. When the content of SiCp increases from 0 to 25 wt%, the number of cracks decreases 93% and the maximum cracks length decreases 92%. Some energy dissipation mechanisms such as crack pinning, transgranular fracture, crack deflection and bifurcation have remarkable effect on crack suppression. In addition, SiCp plays a significant role in eliminating pores, which reduces the porosity from 11.71 to 0.20%. Doping SiCp can increase the temperature and enhance the convection and disturbance of melt pool. Also, it can provide discharge channels for bubbles in melt pool.