This study investigated the effects of the packing density and particle size distribution of TiO₂ nanoparticles on the mechanical properties of TiO₂–epoxy nanocomposites (NCs). The uniform dispersion and good interfacial bonding of TiO₂ in the epoxy resin resulted in improved mechanical properties with the addition of nanoparticles. Reinforcement nano-TiO₂ particles dispersed in deionized water produced by three different ultrasonic dispersion methods were used; the ultrasonication effects were then compared. The nano-TiO₂ suspension was added at 0.5–5.0 wt.%, and the mechanical and thermal properties of TiO₂–epoxy NCs were compared using a universal testing machine, scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FT-IR), and differential scanning calorimetry (DSC). The tensile strength of the NCs was improved by the dispersion strengthening effect of the TiO₂ nanoparticles, and focused sonication improved the tensile strength the most when nano-TiO₂ suspensions with a particle size of 100 nm or smaller were used. Thus, the reinforcing effect of TiO₂ nanoparticles on the epoxy resin was observed, and the nano-TiO₂ suspension produced by focused sonication showed a more distinct reinforcing effect.

Owing to the quick response, compact structure, high precision, huge blocking force generation, and ease of operation, piezoelectric actuators are urgently being adopted in the field of advanced dispensing for jetting performance improvement and fulfillment of precision requirements in microelectronics packaging, adhesive bonding, and miniaturization industry. This research focuses on the fundamental design and development of a piezo-electrically driven compact fluid dispenser using the principle of a class-one lever for amplification of needle displacement, and enhancement of application areas of the developed jet dispenser. Using fundamental lever principle, geometry-based modelling is carried out to fabricate a working prototype of a normally closed hinge-lever type dispenser. Preliminary experiments are carried out to witness the workability of the fabricated dispenser to deliver 100 dots of working fluid per second that will provide a novel device for dispensing of various fluids, and the proposed amplification mechanism suits various other piezoelectric applications as well.

This study has been based on the examination of the characterization of ring-type lead zirconate titanate (PZT) ceramics for high-intensity focused ultrasonic dispersion system. The ring-type PZT ceramics were fabricated by the powder molding method. The mechanical properties, dielectric constant, and microstructure of the ceramics were investigated. Consequently, the density of the ceramics was increased with increasing forming pressure while the density of ceramics that were sintered at 1350 °C was decreased due to over-sintering. Furthermore, the mechanical properties were excellent at the higher forming pressure. The dielectric property of the ring-type PZT ceramics was not clearly influenced by the manufacturing and sintering conditions. The abnormal grain growth of the ceramics, however, could be prevented by a lower heating rate in addition to reducing the porosity.

In this study, the soft-type and hard-type lead zirconate titanate (PZT) ceramics were compared in order to create an optimal system for ultrasonic dispersion of nanoparticles, and sound pressure energy for each PZT ceramic was analyzed and closely examined with ultrasonic energy. TiO₂ was water-dispersed using the soft-type and hard-type PZT transducer, possessing different characteristics, and its suspension particle size and distribution, polydispersity index (PDI), zeta potential, and dispersion were evaluated for 180 days. Furthermore, it was confirmed that the particles dispersed using the hard-type PZT transducer were smaller than the particles dispersed using the soft-type PZT by 15 nm or more. Because the hard-type PZT transducer had a lower PDI, uniform particle size distribution was also confirmed. In addition, by measuring the zeta potential over time, it was found that the hard-type PZT transducer has higher dispersion safety. In addition, it was confirmed that the ultrasonically dispersed TiO₂ suspension using a hard-type PZT transducer maintained constant particle size distribution for 180 days, whereas the suspension from the soft-type PZT aggregated 30 days later. Therefore, the hard-type PZT is more suitable for ultrasonic dispersion of nanoparticles.

Mechanical properties of ring-type lead zirconate titanate (PZT) ceramics were investigated on the effect of sintering condition in this study. The ring-shaped green body of PZT was formed by using HP equipment and then put in the covered crucible. The PZT ceramics was sintered in the pressureless sintering furnace respectively with different heating rate (3℃/min, 5℃/min and 10℃/min). In conclusion, the compressive strength of ring-type PZT ceramics increased with lower heating rate and higher forming pressure. In particular it was greatly influenced by the type of crucible. Vicker’s hardness of PZT ceramics also improved with increasing forming pressure. From the fractography, the change of grain size according to the difference of heating rate and forming pressure has been shown relatively clearly.

Carbonnanotubes are considered as one of ideal fillers for polymer composites because of their outstanding mechanical properties. In this study, the CNT/epoxy nanocomposites were fabricated with the different weight contents and lengths of CNT. Tensile test and hardness test were carried out to investigate the mechanical properties of the CNT/epoxy nanocomposites. The results clearly showed that the tensile strengths of the nanocomposites were greater than that of the pure epoxy. In addition, the nanocomposites with length of 80 μm and 1.0 weight percent CNT showed the best tensile strength. However, the Vickers hardness of nanocomposites were almost the same values regardless of the weight fraction and length of CNT. The CNT has little effect on the pyrolysis temperature of epoxy, so the pyrolysis temperature of CNT/epoxy nanocomposites were almost the same. The fracture surface of CNT/epoxy nanocomposites were much rougher as the CNT content and length increased.