Kyle Sinding

Bismuth Titanate Fabricated by Spray-on Deposition and Microwave Sintering For High-Temperature Ultrasonic Transducers

Thick films of ferroelectric bismuth titanate (Bi4Ti3O12) have been fabricated by spray-on deposition in conjunction with microwave sintering for use as high-temperature ultrasonic transducers. The elastic modulus, density, permittivity, and conductivity of the films were characterized. Electro-mechanical properties of the films were estimated with a commercial d33 meter which gave 16 pC/N. This value is higher than typically reported for bulk bismuth titanate; however, these films withstand higher field strengths during poling which is correlated with higher d33 values. Films were capable of operating at 650 °C for roughly 5 min before depoling and can operate at 600 °C for at least 7 days.

Embedded wireless corrosion detection technology

The Department of Defense spends a substantial portion of their maintenance and sustainment budget on fault detection and repair for aircraft. The sustainment cost of corrosion repair for critical structures, mechanical systems, avionic components and wiring harnesses is in the hundreds of millions of dollars per year. The ability to detect corrosion early in the material deterioration process is a key factor in reducing the financial burden associated with corrosion damage repair. The greatest potential for addressing this problem is through implementation of wireless corrosion detection sensors that can be embedded between the substrate and protective coating, and placed in a number of different critical areas. The intent is to provide the capability to detect the on-set of corrosion/material degradation at the earliest possible time in the fault evolution with minimally intrusive sensor technology. A multidisciplinary Applied Research Laboratory and Pennsylvania State University team is developing a unique embedded wireless corrosion detection sensor that combines spray-on ultrasonic transducers and advanced passive RF wireless interrogation and/or signal transmission. This paper will discuss the development and performance of this sensors for early corrosion detection.

Digital Signal Processing Methods for Ultrasonic Echoes

Digital signal processing has become an important component of data analysis needed in industrial applications. In particular, for ultrasonic thickness measurements, the signal-to-noise ratio (SNR) plays a major role in the accurate calculation of the arrival time. For this application, a bandpass filter is not sufficient since the noise level cannot be significantly decreased such that a reliable thickness measurement can be performed. This paper demonstrates the abilities of two regularization methods-total variation (TV) and Tikhonov-to filter acoustic and ultrasonic signals. Both of these methods are compared with frequency-based filtering for digitally produced signals as well as signals produced by ultrasonic transducers. This paper demonstrates the ability of the TV and Tikhonov filters to accurately recover signals from noisy acoustic signals faster than a bandpass filter. Furthermore, the TV filter has been shown to reduce the noise of a signal significantly for the signals with clear ultrasonic echoes. SNRs have been increased over 400% by using simple parameter optimization. While frequency-based filtering is efficient for specific applications, this paper shows that the reduction of noise in ultrasonic systems can be much more efficient with regularization methods.

Active and passive monitoring of valve bodies utilizing spray-on transducer technology

Structural health monitoring (SHM) and non-destructive evaluation (NDE) can be performed both actively and passively. Active monitoring is useful for thickness measurement and crack interrogation. Passive monitoring can indicate integrity of the valve and if it is open or closed. Traditional SHM methods for valve bodies require a bonding medium that can deteriorate. A sol-gel spray-on technology eliminates the need for a coupling medium since the transducer is chemically bonded to the valve body. These spray-on transducers can be tailored to specific applications in order to maximize response or operating temperature. This technology allows for efficient on-line monitoring of valve bodies for thickness and valve integrity. The current objective is to develop a spray-on transducer and corresponding method for both active and passive SHM of valve bodies. The objective relating specifically to passive monitoring relates to indicating the condition of the valve and determining what position it is in. The acti...

Fabrication and modeling of bismuth titanate-PZT ceramic transducers for high temperature applications

Utilization of a spray-on deposition technique of ferroelectric bismuth titanate (Bi4Ti3O12) composites has a competitive advantage to standard ultrasonic transducers is conforms to non-Euclidean geometries and operates at high temperature (Curie-Weiss temperature 685 °C) and is mechanically coupled to the substrate. However, an issue with many high temperature transducers such as bismuth-titanate ceramics is that they have relatively low d33 (about 12-14 pC/F in Bi4Ti3O12 versus 650 pC/F in PZT-5H). It is common conception that high-temperature capability comes at the cost of electromechanical coupling. It will be shown that the high temperature capability of bismuth-titanate-PZT composite transducers using the spray-on deposition technique previously developed, improves the electro-mechanical coupling while maintaining the high temperature performance and mechanical coupling. This material could provide advantages in harsh environments where high signal to noise ratios are needed.