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Effect of nonstoichiometry on mechanical properties of reactive hot‐pressed monolithic ZrC x Ceramic
Author(s) -
Kannan Rajaguru,
Venkateswarlu Karodi,
Rangaraj Lingappa
Publication year - 2018
Publication title -
international journal of applied ceramic technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.4
H-Index - 57
eISSN - 1744-7402
pISSN - 1546-542X
DOI - 10.1111/ijac.13041
Subject(s) - materials science , fracture toughness , ceramic , composite material , flexural strength , hot pressing , graphite , indentation hardness , indentation , stoichiometry , friction coefficient , elastic modulus , microstructure , chemistry , organic chemistry
The reactive hot pressing (RHP) of Zr:C powder mixture at various molar ratios (1:0.5, 1:0.6, and 1:0.67) at applied pressures of 4‐7 MPa and 1200°C resulted in dense ZrC x ceramics. Nano‐hardness values of ZrC x are reported to be 21‐31 GPa as “x” was varied from 0.5 to 1.0. However, indentation modulus for all ZrC x compositions remained at ~350 GPa. Microhardness of the ZrC x increased from 13 to 15 GPa as the stoichiometry was increased from 0.5 to 1.0. The indentation fracture toughness for ZrC 0.5 was 4 MPa m 1/2 , and for ZrC 0.67 it was reduced to 3.6 MPa m 1/2 . The 3‐point flexural strength for ZrC 0.5 was determined to be 386 ± 26 MPa, which decreased to 316 ± 20 MPa as the carbon content (ZrC 0.67 ) was increased. The dry sliding wear of ZrC 0.5 to ZrC 0.6 indicated that the coefficient of friction was increased from 0.73 to 0.86 at 5 N load and 500 m sliding distance. Further, ZrC 0.67 showed a reduction in friction coefficient of 0.81, and this was due to the increase of strong Zr–C covalent bond and unreacted graphite.