Hongtao SUN
,
Hongfang WANG
,
Liangying ZHANG and Xi YAO(Electronic Materials Research Laboratory
,
Xi'an Jiaotong University
,
Xi'an
,
710049
,
China)
材料科学技术（英）
Under the mechanically free and clamped boundary conditions, electromechanical resonances of ceramic multilayer capacitors are calculated using vibration and piezoelectric equations. Multilayer capacitors made of ferroelectric BaTiO3 and Pb(Mg1/3Nb2/3)O3 ceramics have been used to examine the theoretical calculation. Frequency spectra of impedance and phase angle, capacitance and loss tangent of the capacitors under dc bias fields are carefully measured. A sudden change around the resonant frequency is observed in these spectra. A damped resonance indicates a defective capacitor while an undamped resonance is corresponding to defect free.Experimental results suggest that it is possible to use the spectra as a real time nondestructive evaluation method.
关键词:
Weidou ZHU and Haicheng GU(Dept. of Materials Science and Engineering
,
Xi'an Jiaotong University
,
Xi'an
,
710049
,
China)
材料科学技术（英）
Thin metallic layers (~ 2 μm) of Ni were deposited on polycrystalline Al2O3. ZrO2 and (Ce-TZP)+Al2O3 ceramic substrates. and further irradiated with pulsed excimer (Xeno chloride) laser pulses. The laser energy density was varied from 0.21 to 0.81 J / cm2 to optimize bending strength. For ZrO2 ceramic, it was found that the strength increases from 530 to 753 MPa at 0.51 J / cm2 irradiation. For Al2O3 and (Ce-TZP)+ Al2O3 the fracture strength also increases in varying degree. The causes of strength increment were discussed.
关键词:
