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Mechanical Testing of Ultra-High Temperature Ceramics at 1500°C Air Force Institute of Technology AFIT Scholar Theses and Dissertations Student Graduate Works 3-26-2015 Mechanical Testing of Ultra-High Temperature Ceramics at 1500°C in Air -Development of an Experimental Facility and Test Method Sheena L. Winder Follow this and additional works at: https://scholar.afit.edu/etd Part of the Structures and Materials Commons Recommended Citation Winder, Sheena L., "Mechanical Testing of Ultra-High Temperature Ceramics at 1500°C in Air -Development of an Experimental Facility and Test Method" (2015). Theses and Dissertations. 188. https://scholar.afit.edu/etd/188 This Dissertation is brought to you for free and open access by the Student Graduate Works at AFIT Scholar. It has been accepted for inclusion in Theses and Dissertations by an authorized administrator of AFIT Scholar. For more information, please contact [email protected]. MECHANICAL TESTING OF ULTRA-HIGH TEMPERATURE CERAMICS AT 1500°C IN AIR – DEVELOPMENT OF AN EXPERIMENTAL FACILITY AND TEST METHOD DISSERTATION Sheena L. Winder, Major, USAF AFIT-ENY-DS-15-M-259 DEPARTMENT OF THE AIR FORCE AIR UNIVERSITY Air Force Institute of Technology Wright-Patterson Air Force Base, Ohio DISTRIBUTION STATEMENT A. APPROVED FOR PUBLIC RELEASE; DISTRIBUTION UNLIMITED The views expressed in this dissertation are those of the author and do not reflect the official policy or position of the United States Air Force, Department of Defense, or the United States Government. This material is declared a work of the U.S. Government and is not subject to copyright protection in the United States. AFIT-ENY-DS-15-M-259 MECHANICAL TESTING OF ULTRA-HIGH TEMPERATURE CERAMICS AT 1500°C IN AIR – DEVELOPMENT OF AN EXPERIMENTAL FACILITY AND TEST METHOD DISSERTATION Presented to the Faculty Graduate School of Engineering and Management Air Force Institute of Technology Air University Air Education and Training Command In Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy Sheena L. Winder, BS, MS Major, USAF March 2015 AFIT-ENY-DS-15-M-259 MECHANICAL TESTING OF ULTRA-HIGH TEMPERATURE CERAMICS AT 1500°C IN AIR – DEVELOPMENT OF AN EXPERIMENTAL FACILITY AND TEST METHOD Sheena L. Winder, BS, MS Major, USAF Committee Membership Dr. Marina B. Ruggles-Wrenn Chairman Chair Dr. Robert L. Hengehold Member Dr. Larry W. Burggraf Member ADEDEGI B. BADIRU, PhD Dean, Graduate School of Engineering And Management AFIT-ENY-DS-15-M-259 Abstract With a melting point in excess of 3000°C and a high density, ultra-high temperature ceramics (UHTCs) are a candidate material for hypersonic flight vehicles, atmospheric re-entry vehicles, and rocket propulsion systems. When ceramics are under consideration as a structural material, creep is an important design criterion and frequently a life-limiting condition. However, the characterization of mechanical behavior at temperatures in excess of 1300°C has many challenges to overcome. Of utmost importance is the selection of materials for test fixtures within the test environment. Materials selected must maintain their structural integrity at required temperatures in extreme environments over long durations. In addition, thermo-chemical interaction between the test material and the test fixtures are to be expected at these temperatures. Materials selected must not cause degradation of the test material or interfere with the acquisition of data. An Experimental Facility and Test Method were developed for the mechanical testing of hafnium diboride (HfB2)-UHTCs at 1500°C in air. The thermal compatibility of HfB2 with SX YAG, Pt foil, and alumina was investigated. Exploratory creep tests of hafnium diboride (HfB2)-UHTCs validated single-crystal (SX) yttrium aluminum garnet (YAG) pushrods as acceptable for the application of a constant load over long durations. Platinum foil proved unstable in the presence of HfB2 at 1500°C, rendering it unsuitable as an interlayer between HfB2 and SX YAG. Exploratory testing also validated high purity alumina spacers for utilization in the prevention of the thermo-chemical interaction ~ iv ~ between HfB2 and SX YAG. The results of this research represent a significant contribution towards the use of UHTCs in extreme environments associated with hypersonic flight and atmospheric re-entry. ~ v ~ Dedication With God All Things Are Possible Thank you for my mom and dad. Thank you for the love and support of my husband and two little boys in achieving this milestone. It was crazy, but it would have been miserable without seeing their faces and hearing their laughter. ~ vi ~ Acknowledgements I express my sincere appreciation to my research advisor, Dr. Marina Ruggles- Wrenn, for her guidance, mentorship, and tremendous support throughout the course of the ups and downs of my research. I extend a thank you to Dr. Larry Burggraf and Dr. Robert Hengehold for agreeing to serve as members of my committee, as well as their insight. I would like to thank my supervisor, Diana Carlin, for her patience and support. I would, also, like to thank my sponsor, Dr. Ali Sayir, Program Director, from the Air Force Office of Scientific Research for his continued support of this research endeavor. Thank you to all the men and women of AFIT, AFRL, UES, and Wright State University who provided immeasurable assistance through this endeavor. I thank my mom for her assistance with time and polishing. I want everybody to know my appreciation for my husband who was there every step of the way. He got to polish specimens, setup experiments, pull all-nighters, listen to presentation, and endlessly edit. He was a key to my success. Thank you. ~ vii ~ Table of Contents Abstract……………… ...................................................................................................... iv Dedication………… .......................................................................................................... vi Acknowledgements ........................................................................................................... vii Table of Contents…… ..................................................................................................... viii List of Figures..…… ......................................................................................................... xii List of Tables…… ......................................................................................................... xxiv I. Introduction…… ............................................................................................................1 1.1 Organization of Dissertation .................................................................................1 1.2 Materials for Hypersonic Flight ............................................................................2 1.3 Ultra-High Temperature Ceramics (UHTCs) .......................................................5 1.4 Problem Statement ................................................................................................8 1.5 Material Description .............................................................................................9 1.6 Methodology .......................................................................................................11 II. Background.… .............................................................................................................12 2.1 Ultra-High Temperature Ceramics (UHTCs) .....................................................12 2.2 Synthesis of Diboride-Based UHTCs .................................................................13 2.3 Densification of Diboride-Based UHTCs ...........................................................14 2.4 Oxidation of Diboride-Based UHTCs ................................................................17 2.5 Model Framework and Formulation ...................................................................21 2.6 Mechanical Behavior of Diboride-Based UHTCs ..............................................22 2.7 Thermo-chemical Compatibility and Mechanical Behavior of Diboride-Based UHTCs ................................................................................................................25 2.8 Implications for Current Research ......................................................................28 ~ viii ~ III. Research Plan and Implementation .............................................................................29 3.1 Research Materials ..............................................................................................30 3.1.1 HfB2-containing UHTCs ..........................................................................31 3.1.2 Load Train Materials ................................................................................34 3.2 Characterization of HfB2 Specimens with Varying SiC Content .......................34 3.2.1 Density ......................................................................................................35 3.2.2 Microstructure ..........................................................................................36 3.2.3 Grain Size .................................................................................................38 3.2.4 Physical Dimensions ................................................................................39 3.3 Experimental Facility ..........................................................................................39 3.4 Test Methodology ...............................................................................................48 3.4.1 Testing Facility Temperature Calibration
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