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Influence of Spark Plasma Sintering ( SPS ) Conditions on Transmission of MgAl 2 O 4 Spinel
Author(s) -
Morita Koji,
Kim ByungNam,
Yoshida Hidehiro,
Hiraga Keijiro,
Sakka Yoshio
Publication year - 2015
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/jace.13309
Subject(s) - impurity , spinel , spark plasma sintering , materials science , sintering , microstructure , carbon fibers , analytical chemistry (journal) , precipitation , grain size , coalescence (physics) , contamination , atmospheric temperature range , metallurgy , mineralogy , chemical engineering , composite material , chemistry , chromatography , thermodynamics , composite number , physics , organic chemistry , astrobiology , meteorology , engineering , ecology , biology
The effects of the spark plasma sintering ( SPS ) parameters, such as heating rate α, temperature T and soak time t s , and impurities on in‐line transmission T in were examined in MgAl 2 O 4 spinel. The SPS processing at T = 1300°C for t s = 20 min with a low heating rate of α = 10°C/min is a preferable condition for attaining higher T in . For the higher T or the longer t s , grain coarsening enhanced the coalescence of residual pores and second phase precipitation, resulting to the limited T in even at the slow α. Although the lower T and longer t s attained fine and dense microstructure simultaneously, the maximum T in 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 3 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 T in by the SPS technique, the lower α and T , and the shorter t s should be utilized after removing the impurities.