Research on processing and mechanical properties of Al2O3/3Y-TZP
Date Issued
2006
Date
2006
Author(s)
Weng, Ming-Tsung
DOI
zh-TW
Abstract
In this research, the ceramic feedstocks (Al2O3/3Y-TZP) were
prepared by kneading of plastic formations. The effects of different
additives and kneading sequences to rheological behavior, degree of
homogeneity and mechanical properties of the feedstocks were
investigated. The rheological properties of the feedstock were analyzed
by the torque rheomerty, capillary rheometer. After sintering at suit
temperatures of ≦1600OC, the two-phase microstructure was
quantitatively analyzed by optical and scanning electron microscopy. The
results showed that the component additives (Darvan C+Glycerol) could
increase critical solid loading of feedstock to 57.4 vol%. The kneading
sequence (A3) could input more shear-energy to break-up agglomeration
in the feedstocks. The particles with narrow size distribution and good
dispersion were optimized in the A3 kneading sequence. The yield stress
of feedstock was greater than 0.24 MPa with 2 wt% PVA binder. The
addition of the dry agent (formamide) and γ-Al2O3 with high surface area
could control the water evaporation rate lower than 0.02 g/h*cm2, lower
the flow exponent than 0.3, and increase the plastic index to 3.7%. The
relative sintered density of K-A3 (A70Z) reached 98.2% T.D. as sintered
at 1600OC for 1 hr. The four-point bending strength of K-A3 was 382
MPa with lower Weibull modulus 7.2. The major fracture origins are
large air bubbles and Al2O3 agglomerates.
The second part of this research was adopted colloidal process to
increase the degree of homogeneity of composite microstructure and
control the flaw size distribution. The results showed the relative sintereddensity of C-A70Z reached 99.9% T.D. as sintered at lower temperature
1550OC for 1 hr. The four-point bending strength of C-A70Z was 551
MPa and Weibull modulus 14.5. For C-A85Z with a lower ZrO2 content
(15 vol%), the average bending strength 656 MPa and Weibull modulus
15.1 were obtained.
At different volume ratio of ZrO2 content, the wear mechanism of
the composite will changed from severe brittle fracture (15 vol%) to
plastic deformation (30 vol%) at an applied normal load of 42N and a
sliding velocity of 0.63 m/s. The best wear resistance rate of 7.2×10-8
cm3/Nm was noted in C-A70Z.
Subjects
氧化鋁
氧化鋯
複合材料
混煉
塑性成形
均勻度
膠粒製程
機械性質.
ZrO2
Al2O3
Composite
Kneading
Plastic forming
Homogeneity
Colloidal process
Mechanical properties.
Type
thesis