Transparent magnesium aluminate spinel ceramics were additively manufactured via a laser direct deposition method in this study. With a minimum porosity of 0.3% achieved, highly transparent spinel samples with the highest total optical transmittance of 82% at a wavelength of 632.8 nm, were obtained by a 3D printing approach. However, cracking was found to be a major issue affecting printed spinel samples. To control prevalent cracking, the effect of silica dopants was investigated. Increased silica dopants reduced average total crack length by up to 79% and average crack density by up to 71%. However, a high dopant level limited optical transmission, attributed to increased porosity and formation of secondary phase. Further investigation found that with decreased average fracture toughness, from 2.4 MPa·m1/2 to 1.9 MPa·m1/2, the obvious reduction in crack formation after doping was related to decreased grain size and introduction of softer secondary phase during deposition. The study demonstrated the feasibility of the proposed laser direct deposition method in directly fabricating transparent spinel ceramics while dopants showed potentials in addressing cracking issues.
J. M. Pappas and X. Dong, "Direct 3D Printing of Silica Doped Transparent Magnesium Aluminate Spinel Ceramics," Materials, vol. 13, no. 21, pp. 1-22, MDPI, Nov 2020.
The definitive version is available at https://doi.org/10.3390/ma13214810
Mechanical and Aerospace Engineering
Keywords and Phrases
Additive manufacturing; Laser direct deposition; Magnesium aluminate spinel; Silica doping; Transparent ceramics
International Standard Serial Number (ISSN)
Article - Journal
© 2020 The Authors, All rights reserved.
01 Nov 2020