[nanoPost] Nanocomposite Bond with Carbon Nanotube Films for Nanodevices

Research Centre USA

Structures with the multifunctional capabilities of self-sensing, diagnostics, self-repair, and mitigation of damage have demonstrated many benefits and advantages over traditional structures, particularly in enhancing structural safety, reducing maintenance cost, and improving performance.

The sensor is the most fundamental building block element that is needed for multifunctional structures. The integration of sensors in a network into structures involves serious challenges and difficulties. Although significant progress has been made in recent years, the durability and reliability of sensor networks for covering large structures remain challenges.

This research is proposed to develop a novel technique to enhance the sensor-structure bond strength. We designed, characterized and tested a novel sensor-structure interface. The key feature is the integration of oriented carbon nanotubes (CNTs), into the adhesive. Two fabrications processes were developed during the investigation and will be presented. Through a microscopic examination of the nano-composite adhesive, it was found that CNTs were uniformly dispersed and aligned into the adhesive. The integration of the epoxy with oriented CNTs showed a 300% improvement in the shear strength.

A study was performed to develop a novel technique to enhance the bond strength between a piezoelectric (PZT) actuator and a hosting structure. The bond interface has been considered to be a critical linkage between the structure and the surface-mounted actuators. The loss of interface integrity can have a detrimental effect on the performance of the PZT actuators. The key feature of the proposed technique is to embed a high-density array of oriented carbon nanotubes (CNTs film) into the adhesive layer between the structure and the actuators to enhance the interfacial strength. This presentation focuses primarily on the two fabrication techniques that were developed during the investigation: one is to grow the CNTs directly on the PZT surface at elevated temperatures and the other is to grow the CNTs film on a substrate and then transfer it into the bonding layer at significantly lower temperatures. The latter method is a cost-effective and easy technique which has the potential to be used for structural (as the one proposed here) and for high-performance electronic applications. Through a microscopic examination of the adhesive, it was found that CNTs were uniformly dispersed and aligned into the bonding adhesive. Mechanical tests were performed to investigate the shear strength of the adhesive layer with the embedded CNTs film. Preliminary results show that an increase of the bondline strength up to nearly 300% could be achieved. However a wide data dispersion was also observed and might be attributable to the ratio between the length of the CNTs and the actual PZT-structure gap.