Materials Characterization Breakthrough Leads to Automated Component Health Monitoring

  • Published
  • By Christopher Muratore
  • Materials and Manufacturing
WRIGHT-PATTERSON AIR FORCE BASE, Ohio --  Air Force Research Laboratory materials scientists developed a Raman tribospectrometer--as well as smart wear-resistant materials for use with the device--enabling in situ characterization of such materials at high temperatures. The development is a notable achievement in terms of automatic reporting of wear rates and health monitoring of mechanical components, not only while in place but while in use (i.e., rotating at high speeds or operating in extreme environments). By automating the formerly time-consuming, financially and physically risky manual process for component health monitoring, the new technology will support the creation of coatings and other materials providing optimal thermal and wear protection for Air Force systems.

Facilitating materials assessment during the early stages of systems design, the device instantly identifies surface chemistry during wear testing. Accordingly, it reveals the onset of oxidation or sublimation temperature, the evolution of compound formation, the presence of coating material failure mechanisms, and similarly distinctive factors that can help researchers rely more strongly on measured properties to predict--and thus, avoid--subsequent failures (e.g., coating). Beyond its capacity for surface chemistry evaluation during wear testing, the new device permits the characterization of wear process effects. Further, it helps researchers avoid any misleading results stemming from chemical phases that may develop as materials are cooled to convenient temperatures for handling and posttest characterization purposes.

The tribospectrometer consists of a low-power (25 mW) laser directed towards the coating surface; some simple optics; and a basic detector, which analyzes light scattered from the surface. This light serves as a fingerprint for identifying surface chemistry via luminescence phenomena such as fluorescence (in the case of wear sensors) or Raman scattering for chemical species analysis. In addition to reducing the labor and risk associated with traditional component teardown and rebuild, the automatic health monitoring innovation will also direct the lab's development of new lubricant materials designed to provide lubrication in temperature extremes ranging from 77°F to 1800°F (25°C-1000°C) for air and space platforms alike.

The system is easily miniaturized and robust enough for use at high temperatures and in other adverse ambient conditions. Consequently, researchers in other laboratories (e.g., University of Florida; University of Leoben, Austria; and several others) are currently reproducing this system for their own use, and funding of a Phase II Small Business Innovation Research project for developing a health monitoring system based on this technology is currently under way.vv