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Sinter‐Forging of Nanocrystalline Zirconia: I, Experimental
Author(s) -
Hague Douglas C.,
Mayo Merrilea J.
Publication year - 1997
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.1151-2916.1997.tb02803.x
Subject(s) - nanocrystalline material , materials science , sintering , grain growth , forging , grain size , strain rate , porosity , composite material , metallurgy , cubic zirconia , ceramic , nanotechnology
Nanocrystalline (15 nm) yttria (3 mol%)‐stabilized zirconia (3Y‐TZP) was sinter‐forged under conditions of varying temperature (1050–1200°C), plastic strain rate (5 × 10 −5 to 2 × 10 −3 s −1 ), and green density (33–48%), using constant‐crosshead‐speed tests, constant‐load (i.e., load‐and‐hold) tests, and constant‐loading‐rate tests. The densification and pore size evolution results indicate that plastic strain is largely responsible for elimination of large pores, while diffusional mechanisms control the elimination of small pores. Grain growth during sinter‐forging is observed to be dependent solely on porosity during intermediate‐stage sintering. Once the powder compact enters final‐stage sintering, however, both static (time‐ and temperature‐dependent) and dynamic (plastic‐strain‐dependent) grain growth take place, greatly accelerating the overall rate of grain growth. The use of fast strain rates to impose plastic strain before the onset of dynamic grain growth is proposed as a method of preserving small grain sizes during sinter‐forging.