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Document Type

Campus Access

Degree Program

Mechanical Engineering

Degree Type

Master of Science in Mechanical Engineering (M.S.M.E.)

Year Degree Awarded

2009

Month Degree Awarded

September

Keywords

creep, high temperature material

Abstract

Currently, the design of high temperature mechanical components is limited by material performance at elevated temperatures. Rocket nozzle materials, for example, need to survive exhaust gas temperatures up to 3000 ºC under high stresses for short periods of time. Additionally, one of the current challenges in hypersonic flight is the development of materials that will withstand the leading edge temperatures which exceed 2700 ºC. In these severe environments, the characterization of materials’ creep properties is essential.

Conventional creep testing methods are limited to 1700°C. Using ESL, a group of researchers at the University of Massachusetts Amherst developed a non-contact creep method, which is not subject to such temperature limits. Using the non-contact method a spherical sample is rotated rapidly, and the driving load is applied by centripetal acceleration, which causes deformation. During previous creep tests, a laser supplied both the heating and driving rotational force to the sample. Since the rotation is controlled by the photon pressure emitted from the heating laser, the applied stress is coupled to the testing temperature. By developing an independent rotation control, non-contact creep tests could be conducted on a wider range of materials. A specialized high-speed induction motor was developed for use in high-temperature creep tests.

In addition to creep behavior, the understanding of thermophysical properties is important for the emerging class of high temperature material. Using a previously developed method, non-contact density measurements were taken concurrently on the same materials as X-ray diffraction measurements. Over 35 materials were successfully processed including, aluminum, copper, hafnium, palladium, nickel, titanium and zirconium based alloys. Besides contributing to high temperature material databases, density measurements provide an understanding of solidus formation and short-range order in the liquid state.

First Advisor

Robert W Hyers

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