Influence of Spark Plasma Sintering (SPS) Conditions on Transmission of MgAl2O4 Spinel. Issue 2 (6th November 2014)

• Record Type: Journal Article
• Authors: Morita, Koji; Kim, Byung‐Nam; Yoshida, Hidehiro; Hiraga, Keijiro; Sakka, Yoshio; Reimanis, I.
• Is Part Of: Journal of the American Ceramic Society. Volume 98:Issue 2(2015)
• Page Start: 378
• Page End: 385
• Publication Date: 2014-11-06
• Subjects: Ceramics -- Periodicals; 620.1405
• DOI: 10.1111/jace.13309
• Languages: English
• ISSNs: 0002-7820

Abstract

<abstract abstract-type="main" id="jace13309-abs-0001"> <title> <x xml:space="preserve">Abstract</x> </title> <p>The effects of the spark plasma sintering (SPS) parameters, such as heating rate α, temperature <italic>T</italic> and soak time <italic>t</italic><sub>s</sub>, and impurities on in‐line transmission <italic>T</italic><sub>in</sub> were examined in MgAl<sub>2</sub>O<sub>4</sub> spinel. The SPS processing at <italic>T </italic>=<italic> </italic>1300°C for <italic>t</italic><sub>s</sub> = 20 min with a low heating rate of α = 10°C/min is a preferable condition for attaining higher <italic>T</italic><sub>in</sub>. For the higher <italic>T</italic> or the longer <italic>t</italic><sub>s</sub>, grain coarsening enhanced the coalescence of residual pores and second phase precipitation, resulting to the limited <italic>T</italic><sub>in</sub> even at the slow α. Although the lower <italic>T</italic> and longer <italic>t</italic><sub>s</sub> attained fine and dense microstructure simultaneously, the maximum <italic>T</italic><sub>in</sub> was limited to about 50%. The limited transmission, particularly in the visible range, can be ascribed to the discoloration caused by the carbon contamination. The carbon contamination arose from the preexisting trace CO<sub>3</sub> impurities, irrespective of the SPS conditions. For the higher α, which is the primary advantage of the SPS technique, the additional carbon contamination occurred from the paper/die and remained as glassy carbon in the matrix. To attain higher <italic>T</italic><sub>in</sub> by the SPS technique, the lower α and <italic>T</italic>, and the shorter <italic>t</italic><sub>s</sub> should be utilized after removing the impurities.</p> </abstract>