Effect of cooling rate on tetragonal to monoclinic transformation in hot pressed ZrO{sub 2}(Y{sub 2}O{sub 3}) ceramics

Journal Article · Wed Nov 01 04:00:00 EST 1995 · Scripta Metallurgica et Materialia

DOI:https://doi.org/10.1016/0956-716X(95)00424-T· OSTI ID:116072

Zhu, W Z; Ding, Z S ^[1]; Lei, T C; Zhou, Y ^[2]

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1. Zhejiang Univ., HangZhou (China)
2. Harbin Inst. of Tech. (China). Dept. of Metals and Technology

It is well documented that the tetragonal (T) to monoclinic (M) transition in either pure zirconia or partially stabilized zirconia is the origin of toughening in that resistance to the propagation of cracks can be greatly enhanced by the concurrent appearance of the stress field of the transformation. In the present paper, the effect of cooling rate on the T {yields} M phase transformation in yttria-containing zirconia and its resultant mechanical properties have been studied by means of thermal expansion analysis. Both the T {yields} M and M {yields} T transformations are affected by the cooling and heating rates, respectively. The amount of M-phase decreases with increasing cooling rate. T {yields} M transition occurring within the interior part of specimen can be completely inhibited by the cooling rate of 100 C/min for ZrO{sub 2}(2mol% Y{sub 2}O{sub 3}) ceramic sintered at 1,600 C. The start point and end point of the T {yields} M transformation decreases and increases, respectively, with increasing cooling rate. Both the start point and end point of the M {yields} T transformation increase with increasing cooling rate. The divergence between the results of X-ray diffraction and the thermal expansion analysis has been rationalized in terms of the both internal and external factors, namely, preferential sites of surface for the formation of the M-phase and limited sensitivity of measurement of the thermal expansion apparatus. Both the water-cooled and air-cooled specimens show much improved mechanical properties regardless of the sintering temperatures or yttria content because of the relatively higher T-phase fraction retained to room temperature.

• OSTI ID: 116072
• Journal Information: Scripta Metallurgica et Materialia, Journal Name: Scripta Metallurgica et Materialia Journal Issue: 9 Vol. 33; ISSN 0956-716X; ISSN SCRMEX
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ANISOTROPY
CHEMICAL COMPOSITION
CRYSTAL-PHASE TRANSFORMATIONS
FRACTURE PROPERTIES
HARDNESS
HEAT TREATMENTS
STRESSES
THERMAL EXPANSION
X-RAY DIFFRACTION
YTTRIUM OXIDES
ZIRCONIUM OXIDES