Chutima Eamchotchawalit

Electrophoretic deposition of lead zirconate titanate (PZT) powder from ethanol suspension prepared with phosphate ester

Abstract The formation of thick PZT films via electrophoretic deposition (EPD) was studied. The colloidal suspension of a nano-sized PZT powder dispersed in ethanol was prepared using a phosphate ester (PE) as a dispersant. The amount of PE addition on the stability of the PZT suspension has been investigated by measuring the pH and conductivity of the suspension, deposition weight and the relative density of the PZT green compacts. The effect of the applied voltage on the relative green density was also determined as a function of the wt% PE. The composition and microstructure of the sintered PZT ceramics were characterized by XRD and SEM. The electrical properties of the PZT ceramics were also investigated.

Comparison of actuator performance in lead-based and lead-free piezoelectric cymbals

Class V flextensional actuator named “cymbal” is composed of a ceramic disk that is sandwiched between two truncated conical metal endcaps. It has received considerable attention for sensor and actuator applications due to their high displacement and moderate generative force. It is well known that the strain/displacement of the piezoelectric ceramic correlated to the piezoelectric coefficient and external electric field applied (S = dE). According to the piezoelectric coefficient (d33) of KNN-LT-LS lead-free piezoelectric ceramic was comparable to PZT-8. Therefore, the purpose of this study was to investigate the effect of different ceramic driving elements (hard PZT and KNN-LT-LS ceramics) in the flextensional cymbal actuator on the strain amplification as well as the characteristic in strain-electric field loop response. The results showed that displacement of KNN-LT-LS cymbal (11.9±0.28 μm) were two times higher than that of PZT-8 cymbal (5.65±0.07 μm) at 10 kV/cm. Moreover, bi-polar S-E loop characteristic was larger in KNN-LT-LS cymbal compared to PZT-8 cymbal. This was due to easily domain reorientation in KNN-LT-LS ceramic observed by P-E loop. Under 10 kV/cm, Pr and Ec of KNN-LT-LS ceramic were 4.9 μC/cm2 and 3.9 kV/cm whereas Pr and Ec of PZT-8 ceramic were 0.22 μC/cm2 and 1.5 kV/cm, respectively.

Dispersion Stability of Drinking Water Treatment Sludge

The objective of this study is to improve the particle suspension stability of drinking water treatment sludge (DWTS) and comparable to other silicate powder which are bentonite, micro silica (micro-SiO2), and nano-silica (nano-SiO2). The main dispersion characteristic are related to particle size, and dispersion force. The representative samples of bentonite, micro-SiO2, nano-SiO2, and DWTS were dispersed at the same solid content in water. The particle size distribution and chemical composition of samples were analyzed. The suspended samples were measured for Zeta potential at the controlled pH value. Furthermore, turbidity of suspended samples were investigated at various sedimenting time. The results indicated that nano-SiO2 has the highest Zeta potential value at pH 8-12. The stability of particle dispersion could be implied from turbidity of suspension at various sedimenting time. Bentonite suspension performed more stability than other samples for longer time. However, stability of DWTS particles can be improved by particle size controlling and treatment with dispersion agent to create repulsive force from the charge on the particle surface.

Effect of MnCO3 Doping on Microstructure and Electrical Properties of PSZT Ceramics

The effect of manganese doping on microstructure, piezoelectric and electromechanical properties of Pb0.94Sr0.06(Zr0.52Ti0.48)O3 (PSZT) ceramics has studied. The PSZT ceramics doped MnCO3 concentration in the region of 0-1.0 mol% were prepared by a solid-state reaction and conventional sintering process. Phase identification showed the formation of single phase perovskite structure in all compositions. Microstructure and fracture behavior were observed by scanning electron microscopy (SEM). The fracture behavior demonstrated the change of fracture type from trangranular to mix of trans-and inter-granular type with increasing the amount of MnCO3. Dielectric constant (K), d33 and kp were increased when higher amount of MnCO3 was doped. In addition, the mechanical quality factor (Qm) was highest at 0.1 mol% MnCO3 doping in PSZT ceramics.

The Effect of Metallic Plate on the Displacement in Bilayer Piezoelectric/Electrostrictive Dome Unimorph

A dome piezoelectric-electrostrictive monolithic bilayer composite (PE-MBLC) actuator is attached to a thin metallic plate by insulating epoxy resin to form a flextensional actuator. Such flextensional actuator is called bilayer piezoelectric/electrostrictive dome unimorph (BIPEDU). Under the application of an electric field, the force generated from radial contraction of PE-MBLC was transferred through the bonding area to deform the metallic plate, generating more displacement in BIPEDU actuator. In this study, a PE-MBLC with the P:E volume ratio of 8:2 was used as the active driving element and a metallic plate served as a flextensional structure. Different type of metallic plates showed different in the flexibility which will effect to strain amplification in BIPEDU. Therefore, the investigation of various metallic plates including stainless steel, brass, and aluminum with their thicknesses of 76 μm on the displacement of BIPEDU has studied. To examine the displacement, all PE-MBLCs and BIPEDUs were subjected to an E-field of 10 kV/cm. The results showed that displacement of all BIPEDUs with stainless steel, brass, and aluminum yielded higher displacement compared to PE-MBLCs. In addition, the experimental results of displacement in BIPEDUs with three different types of metallic plates indicated that the BIPEDU fabricated by using 76 μm thickness stainless steel yielded the highest displacement of ≈65 μm while BIPEDUs with brass and aluminum showed 45 and 32 μm, respectively.