A Sensor for Water Detection in Aircraft Adhesive Bondlines
Abstract
A simple and low cost sensor for detecting the water ingress in the adhesive bond line was designed. A compressed polypyrrole (PPy) powder was embedded in an epoxy adhesive sandwiched between two aluminium (2024) substrates. Interactions between PPy and water resulted in a rapid increase in resistivity. The DC resistivity increased more than 20 times the initial value when the PPy was contacted by water. The increase was consistent with AC impedance at low frequencies which showed 10 times increase if one PPy disc (3 mm diameter) was embedded or 100 times increase if there were 3 PPy disc embedded when the cell was immersed in a brine solution for approximately 1000 h. The resistivity of compressed PPy embedded in the bondline was unchanged after 2000 h ageing at 100 C. This indicates a good thermal stability. An initial test indicated that the inclusion of a single 5mm diameter PPy disc in a 25mm diameter bonded joint did not significantly decrease the dry adhesive strength of the adhesive joint. These results indicate that the sensor could potentially meet the requirements of a bond degradation sensor in terms of: (1) low cost (few cents for one PPy disc); (2) sensitivity to water; (3) long-term stability; (4) ease of monitoring; and (5) sustaining the dry bond strength.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 01, 2000
- Accession Number
- ADA378422
Entities
People
- C. L. Olsson-jacques
- M. S. Russo
- R. F. Muscat
- V. T. Truong
Organizations
- Defence Science and Technology Group