N112-087 TITLE: Cumulative Moisture Sensor for Ceramic Fabrics

TECHNOLOGY AREAS: Air Platform, Materials/Processes, Sensors

ACQUISITION PROGRAM: F-35, Joint Strike Fighter

OBJECTIVE: Develop a passive sensor to measure the cumulative moisture absorbed by ceramic fabric.

DESCRIPTION: Ceramic fabrics are used during the production of ceramic matrix composites. The ceramic fabric spools are stored in a climate controlled environment prior to use. During production, the spools are removed from the controlled environment and the required amount of fabric is removed from the spool. In some cases during storage, the environment may be compromised due to equipment failure or dry-bag leaks. These events lead to moisture ingress into the ceramic fabric and cause the moisture content to rise above acceptable limits, rendering the fabric unusable. Longer exposure at lower humidity may be more detrimental than a short spike in humidity.

The current industrial practice is to use qualitative humidity sensors. These sensors change color when a certain trigger-humidity is reached and is not indicative of actual moisture absorbed by the fabric. This is combined with manual logs used to record the out time of the fabric while on the shop floor and the temperature and humidity in the shop at the time the fabric is exposed. To enable stricter monitoring of the moisture content and also to minimize human error, a passive traveling sensor is desired. This sensor will be stored with the fabric and will be exposed to the same environment as the fabric. The sensor should absorb moisture in a manner that can be calibrated to that absorbed by the fabric. The absorption has to be measurable either through a change in mechanical or electrical property or another property. This property should be readable quickly and in a non-destructive fashion.

PHASE I: Develop an approach to sense the cumulative moisture absorbed by the ceramic fabric. Demonstrate the feasibility of such approach by formulating a laboratory study.

PHASE II: Develop a cumulative moisture sensor prototype based upon the Phase I approach. Evaluate the process through fabrication and testing of the prototype sensor.

PHASE III: Transition the approach to appropriate platforms and additional propulsion and high temperature applications.

PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: This sensor could be used in the small but growing ceramic matrix composite (CMC) industry in the civilian sector. It could also be adapted for use in any civilian application needing monitoring of cumulative moisture content of stored inventory.

REFERENCES:
1. Chawla, K. K. (2003). Ceramic matrix composites, 2nd Edition, Kluwer Academic Publishers.

2. Control Company - http://www.control3.com/4192p.htm

KEYWORDS: ceramic fabric; sensor; humidity; moisture; quality control; usable life sensor

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