Advanced spinel and sub-μm Al2O3 for transparent armour applications

Effects of the nature of the doping salt and of the thermal pre-treatment and sintering temperature on Spark Plasma Sintering of transparent alumina

“…Recently, Stuer et al [5] increased the RIT of Spark Plasma Sintered PCA up to 57% at 640 nm, by tridoping the powder with Mg, La and Y which proves the benefit of combining the strategy of doping with SPS. However, their RIT values are still far from those found by Krell et al [2] using HIP (72% at 640 nm). Green body shaping was shown to be of crucial importance by Krell et al [21] for natural sintering.…”

“…The whole weight loss, close to 3 wt% was five to tenfold higher than that calculated for the transformation into oxide of the amount of doping chloride or nitrate, i.e. respectively 0.30 and 0.59 wt% for MgCl 2 and Mg(NO 3 ) 2 . Below 250 8C, the two first losses are undoubtedly attributed to the release of adsorbed water and above 250 8C it is difficult to distinguish the end of dehydration and the start of decomposition of the doping salts.…”

“…For both mechanical and economical reasons, numerous studies have been performed over recent years to replace sapphire by transparent polycrystalline alumina (PCA) in various optical applications such as discharge lamp envelopes and optical windows or armour [1][2][3][4][5]. The light transmission properties of fine-grained PCA can be described by the Apetz and van Bruggen model [6], based on the Rayleigh-GansDebye approximation.…”

Transparent polycrystalline alumina using spark plasma sintering: Effect of Mg, Y and La doping

“…For post-HIP treated samples, results for undoped, 5 singledoped (Mg 2+ , Ti 4+ ) 1,3,9 and co-doped (Ca 2+ -Ti 4+ ) 10 PCA have been reported so far. This method gave fairly reproducible RITs between different groups with values up to 65%.…”

“…Over recent years, attempts have been made to replace sapphire by transparent polycrystalline alumina (PCA) [1][2][3][4][5][6] for both economic and ecological reasons.…”