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Microstructure and mechanical properties of TaC ceramics with 1–7.5 mol% Si as sintering aid
Author(s) -
Geng Guihong,
Liu Limeng,
Wang Yujin,
Hai Wanxiu,
Sun Wenzhou,
Chen Yuhong,
Wu Laner
Publication year - 2017
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.14806
Subject(s) - materials science , spark plasma sintering , microstructure , sintering , ceramic , fracture toughness , flexural strength , dissolution , grain size , carbide , silicon carbide , tantalum , tantalum carbide , composite material , metallurgy , chemical engineering , engineering
Metallic Si as sintering aid was effective in densifying tantalum carbide ceramic (TaC) by spark plasma sintering ( SPS ) at 1700°C. Full density was reached at 5.0 mol% Si addition (equivalent to 1.088% Si in weight) and above. Enhanced densification of TaC ceramic with Si was associated with decrease in oxygen content from ~0.24 wt% in TaC powder to ~0.03 wt% in consolidated specimen. Rest of the oxygen species was collected at multigrain conjunctions to form SiO 2 ‐based liquid at high temperatures. Upon cooling, Ta, Si, O, and C dissolving in the liquid precipitated minor phases of TaSi x and SiC of low concentrations. Microstructure of TaC ceramics was refined by the Si addition, with average grain size decreasing from 11±8 μm at 1.0 mol% Si to 3±2 μm at 7.5 mol% Si addition. Ta solute in SiC and Si solute in TaC were evidenced. TaC ceramic containing 7.5 mol% Si had a relatively good flexural strength and fracture toughness of 646±51 MPa and 5.0 MPa·m 1/2 , respectively.