The Effect of Grain Size on the Mechanical and Optical Properties of Spark Plasma Sintering‐Processed Magnesium Aluminate Spinel MgAl₂O₄

Abstract

The study deals with the effect of the SPS parameters and LiF doping on the mechanical and optical properties polycrystalline magnesium aluminate spinel (PMAS) with emphasis on the grain size of the final product. Sintering at 1300°C of undoped powder yielded fully dense submicrometer (0.4–0.6 μm) samples with elevated mechanical properties (1600HV and 300MPa bending strength). Doped samples had a larger, 40 μm grain size, lower, 1450HV, hardness and 150MPa bending strength. The transmittance of the doped samples (80% at 500 nm wavelength) was higher than that of the undoped ones. Thus, the required functionality of the ceramic dictates the choice of parameters for the fabrication of dense transparent PMAS.

The Effect of Lithium Doping on the Sintering and Grain Growth of SPS-Processed, Non-Stoichiometric Magnesium Aluminate Spinel

“…These values are in agreement with the lower coarsening tendency of aluminum-rich spinels [15]. Spark plasma sintering is a well-established method for sintering transparent magnesium aluminate spinel [10,16,17,18,19,20,21,22,23,24] which combines axial pressure with heating via an electrical current passing through a die containing the powder body. A LiF sintering additive (~1 wt.…”

Aqueous gelcasting of the transparent MgAl2O4 spinel ceramics

“…Generally, transparent MgAl 2 O 4 spinel ceramics were fabricated using lithium fluoride (LiF) as sintering aids by traditional hot pressing (HP) directly or HP combined with hot isostatic pressing (HIP) technology [5][6][7][8], and both steps are performed at relatively high temperatures. However, the size and shape of sample was limited due to the size and shape of processing equipments.…”

Surface engineering alumina armour ceramics with laser shock peening

“…Therefore, an increase in the hardness by means of dislocation motion and most likely an effect of increased dislocation density occurred. Addition to this, it should also be noted that the Hall-Petch boundary grain boundary theory is also applicable to ceramic as well as metallic systems and has been reported by the work of Rothman et.al [58] and Trunec [59]. Beyond the scope of this paper, further studies addressing specifically the dynamics of the dislocation density are planned.…”