Fabrication of combined 0–3 and 1–3 connectivities PZT/epoxy resin composites

PZT/epoxy resin composites of combined 0–3 and 1–3 connectivities were fabricated, for the first time, using suction, dice and fill techniques. Two types of composites (PZT(m)/epoxy resin and PZT(sp)/epoxy resin) were produced using PZT powders prepared by mixed oxide and spray-drying methods. Physical, mechanical, dielectric and piezoelectric properties of the composites were examined. Generally, overall results between the two composites were found to be very similar (volumetric changes ∼34–37%, d₃₃∼20.2–25.3 pC/N, K_p∼0.54–0.61). Higher density was found in PZT(sp)/epoxy resin, however, due to better packing of particles. Moreover, both PZT/epoxy resin composites exhibited very low acoustic impedance (Z∼4.12–4.84 Mrayls), which is very close to that of human tissue and water. Therefore, these new composites may be suitable for use in medical applications. PACS 81.05.Qk; 81.05.Zx; 77.87.-s     

Acoustic and Piezoelectric Properties of 0–3 Connectivity Environmental-Friendly Lead-Free BCTS–Portland Cement Composites

Physics of the Solid State - New environmental-friendly lead-free barium calcium stannate titanate (BCTS)–Portland cement (PC) composites were studied and fabricated to be compatible with the...     

Effect of nanoporous In2O3 film fabricated on TiO2-In2O3 photoanode for photovoltaic performance via a sparking method

Journal of Solid State Electrochemistry - A simple and inexpensive sparking method was used to deposit body-centered cubic In2O3 film on TiO2 photoanode for 30–180 min for...     

Thermogravimetry analysis,compressive strength and thermal conductivity tests of non-autoclaved aerated Portland cement–fly ash–silica fume concrete

Journal of Thermal Analysis and Calorimetry - This paper reports the investigated thermogravimetry analysis, compressive strength and thermal conductivity tests of non-autoclaved aerated Portland...     

Effect of curing time on the hydration and material properties of cold-bonded high-calcium fly ash–Portland cement lightweight aggregate

Journal of Thermal Analysis and Calorimetry - Artificial aggregates, such as fly ash lightweight aggregates, can be used as eco-friendly alternatives to natural aggregates. This work aims to...     

Dielectric, ferroelectric and piezoelectric properties of 0-3 barium titanate–Portland cement composites

In this work, barium titanate (BT) and cement composites of 0-3 connectivity were produced with BT concentrations of 30%, 50% and 70% by volume using the mixing and pressing method. The dielectric constant (ε _r ) and the dielectric loss (tan δ) at room temperature and at various frequencies (0.1–20 kHz) of the ferroelectric BT-Portland cement composites with different BT concentrations were investigated. The results show that the dielectric constant of BT-PC composites was found to increase as BT concentration increases, and that the highest value for ε _r —of 436—was obtained for a BT concentration of 70%. In addition, the dielectric loss tangent decreased with increasing BT concentration. Moreover, several mathematical models were used; the experimental values of the dielectric constants are closest to those calculated from the cube model. The 0-3 cement-based piezoelectric composites show typical ferroelectric hysteresis loops at room temperature. The instantaneous remnant polarization (P _ir ), at an applied external electrical field (E ₀) of 20 kV/cm (90 Hz) of 70% barium titanate composite, was found to have a value ≈3.42 μC/cm². Furthermore, the piezoelectric coefficient (d ₃₃) was also found to increase as BT concentration increases, as expected. The highest value for d ₃₃ was 16 pC/N for 70% BT composite.     

Thermal analysis and microstructure of Portland cement-fly ash-silica fume pastes

Thermal analysis (thermogravimetry and differential thermal analysis) was used with scanning electron microscopy technique to investigate the hydration mechanisms and the microstructure of Portland cement-Fly ash-silica fume mixes. Calcium silicate hydrate (C–S–H), ettringite, gehlenite hydrate (C₂ASH₈), calcium hydroxide (Ca(OH)₂) and calcium carbonate (CaCO₃) phases were detected in all mixes. In the mixes with the use of silica fume addition, there is a decrease in Ca(OH)₂ with increasing silica fume content at 5 and 10% compared to that of the reference Portland-fly ash cement paste and a corresponding increase in calcium silicate hydrate (C–S–H).     

Interfacial morphology and domain configurations in 0-3 PZT-Portland cement composites

Cement-based piezoelectric composites have attracted great attention recently due to their promising applications as sensors in smart structures. Lead zirconate titanate (PZT) and Portland cement (PC) composite were fabricated using 60% of PZT by volume. Scanning Electron Microscope and piezoresponse force microscope were used to investigate the morphology and domain configurations at the interfacial zone of PZT-Portland cement composites. Angular PZT ceramic grains were found to bind well with the cement matrix. The submicro-scale domains were clearly observed by piezoresponse force microscope at the interfacial regions between the piezoelectric PZT phase and Portland cement phase, and are clearer than the images obtained for pure PZT. This is thought to be due to the applied internal stress of cement to the PZT ceramic particle which resulted to clearer images.     

Thermogravimetry of ternary cement blends

This study reports the microstructure characteristic and compressive strength of multi-blended cement under different curing methods. Fly ash, ground bottom ash, and undensified silica fume were used to replace part of cement at 50 % by mass. Mortar and paste specimens were cured in air at ambient temperature, water at 25, 40, and 60 °C and sealed with plastic sheeting for 28 days. In addition, these specimens were cured in an autoclave for 6, 9, and 12 h. Results indicated that the compressive strength of multi-blended mixes containing silica fume 10 % by mass cured with plastic sealed and cured in water at 25 and 40 °C was similar to or higher than the corresponding Portland cement control at 28 day. Moreover, the mixes containing silica fume 10 % by mass cured in water at 60 °C had higher compressive strength than Portland cement control. X-ray diffraction and thermogravimetry results confirmed that there was increased pozzolanic reaction with increasing silica fume content which relates to the increasing in strength. For autoclaved curing, the compressive strength of multi-blended cement specimens with silica fume (total of 50 % replacement) was noticeably higher than control Portland cement mix and was highest when autoclaving time was 9 h. X-ray diffraction results showed the pattern of 0.9, 1.1, and 1.4 nm tobermorite crystalline phases as the main product of this curing. Thermogravimetry results showed dehydration of 1.4 nm tobermorite and 1.1 nm tobermorite at about 80–90 and 135–150 °C, respectively. Tobermorite (also shown by scanning electron microscope) thereby as a result lead to significant compressive strength improvement in the short time of autoclaved curing.     

Thermogravimetric analysis and phase characterizations of Portland fly ash limestone cements

Journal of Thermal Analysis and Calorimetry - Three-dimensional rotating flow of water-based carbon nanotubes is investigated in the presence of Darcy–Forchheimer porous space and...