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Powder Processing Effects on the Rapid Low‐Temperature Densification of ZrB 2 –SiC Ultra‐High Temperature Ceramic Composites Using Spark Plasma Sintering
Author(s) -
Walker Luke S.,
Pinc William R.,
Corral Erica L.
Publication year - 2012
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/j.1551-2916.2011.04873.x
Subject(s) - materials science , spark plasma sintering , sintering , ceramic , composite material , porosity , ball mill , composite number
Investigating the powder processing effects on a ZrB 2 –25 vol% SiC ceramic composite densified using spark plasma sintering ( SPS ) allows for identification of densification mechanisms and enables a reduction in sintering temperature to a minimum of 1650°C. Attrition milling ( AM ) and ball milling ( BM ) were investigated as processing methods to produce a fine and coarse powder densified using SPS with or without a tube furnace preheat treatment. Ceramics formed from AM and BM powders contain 1.66 wt% oxygen contamination, primarily ZrO 2 and SiO 2 , and 0.35 wt% oxygen contamination as SiO 2 , respectively. Heat treatment slightly reduces oxygen contamination but has significant impacts on the densification mechanisms. Without heat treatment, powder coarsening dominates the initial sintering process in the SPS inhibiting densification until ~1350°C. After heat treatment, sintering and densification is enabled at low temperature, 1000°C–1100°C. The densification of ZrB 2 –SiC composites can be broken into a two‐step process with phase 1 as the sintering step based on powder surface area reduction and phase 2 as a forging step where high‐temperature creep and pressure eliminate porosity after the primary grains have formed. A time–temperature‐density plot illustrates the change in densification mechanism used to fully densify ZrB 2 –SiC composites in SPS .