UCLA UCLA Electronic Theses and Dissertations Title Synthesis, Structure, and Properties of Refractory Hard-Metal Borides Permalink https://escholarship.org/uc/item/1hv5m731 Author Lech, Andrew Thomas Publication Date 2014 Peer reviewed|Thesis/dissertation eScholarship.org Powered by the California Digital Library University of California UNIVERSITY OF CALIFORNIA Los Angeles Synthesis, Structure, and Properties of Refractory Hard-Metal Borides A dissertation submitted in partial satisfaction of the requirements for the degree of Doctor of Philosophy in Chemistry by Andrew Thomas Lech 2014 ©Copyright by Andrew Thomas Lech 2014 ABSTRACT OF THE DISSERTATION Synthesis, Structure, and Properties of Refractory Hard-Metal Borides by Andrew Thomas Lech Doctor of Philosophy in Chemistry University of California, Los Angeles, 2014 Professor Richard B. Kaner, Chair As the limits of what can be achieved with conventional hard compounds, such as tungsten carbide, are nearing reach, super-hard materials are an area of increasing industrial interest. The refractory hard metal borides, such as ReB 2 and WB 4, offer an increasingly attractive alternative to diamond and cubic boron nitride as a next-generation tool material. In this Thesis, a thorough discussion is made of the progress achieved by our laboratory towards understanding the synthesis, structure, and properties of these extremely hard compounds. Particular emphasis is placed on structural manipulation, solid solution formation, and the unique crystallographic manifestations of what might also be called “super- hard metals”. ii The dissertation of Andrew Thomas Lech is approved. ____________________________________________ Sarah Tolbert ____________________________________________ Vijay Gupta ____________________________________________ Richard B. Kaner, Committee Chair University of California, Los Angeles 2014 iii TABLE OF CONTENTS ABSTRACT OF THE DISSERTATION .......................................................................................................................... II LIST OF FIGURES .................................................................................................................................................. VII LIST OF TABLES .................................................................................................................................................... XV DEDICATION ...................................................................................................................................................... XVII ACKNOWLEDGEMENTS ..................................................................................................................................... XVIII VITA .................................................................................................................................................................... XIX PUBLICATIONS AND PRESENTATIONS .................................................................................................................. XX CHAPTER 1 ............................................................................................................................................................. 1 INTRODUCTION .............................................................................................................................................................. 1 MOTIVATION ................................................................................................................................................................. 1 BORIDES ....................................................................................................................................................................... 4 CHAPTER 2 ........................................................................................................................................................... 20 SUPER -HARD SOLID -SOLUTIONS OF TUNGSTEN IN RHENIUM DIBORIDE .................................................................................. 20 INTRODUCTION ............................................................................................................................................................ 20 MATERIALS AND METHODS ............................................................................................................................................ 23 RESULTS ..................................................................................................................................................................... 26 DISCUSSION ................................................................................................................................................................ 28 CONCLUSIONS ............................................................................................................................................................. 32 CHAPTER 3 ........................................................................................................................................................... 54 “T UNGSTEN TETRABORIDE ” ...................................................................................................................................... 54 INTRODUCTION ............................................................................................................................................................ 54 MATERIALS AND METHODS ............................................................................................................................................ 56 iv RESULTS AND DISCUSSION ............................................................................................................................................. 59 CONCLUSIONS ............................................................................................................................................................. 63 CHAPTER 4 ........................................................................................................................................................... 70 BEHAVIOR UNDER HIGH PRESSURE .................................................................................................................................. 70 INTRODUCTION ............................................................................................................................................................ 70 MATERIALS AND METHODS ............................................................................................................................................ 72 RESULTS ..................................................................................................................................................................... 75 DISCUSSION ................................................................................................................................................................ 77 CONCLUSIONS ............................................................................................................................................................. 82 CHAPTER 5 ........................................................................................................................................................... 94 SOLID SOLUTIONS OF TUNGSTEN “T ETRABORIDE ” .............................................................................................................. 94 INTRODUCTION ............................................................................................................................................................ 94 MATERIALS AND METHODS ............................................................................................................................................ 95 RESULTS AND DISCUSSION ............................................................................................................................................. 98 CONCLUSIONS ........................................................................................................................................................... 105 CHAPTER 6 ......................................................................................................................................................... 122 THE STRUCTURE OF “WB 4” ......................................................................................................................................... 122 INTRODUCTION .......................................................................................................................................................... 122 MATERIALS AND METHODS .......................................................................................................................................... 125 RESULTS ................................................................................................................................................................... 127 DISCUSSION .............................................................................................................................................................. 128 CONCLUSIONS ........................................................................................................................................................... 134 CHAPTER 7 ......................................................................................................................................................... 143 CONCLUSIONS ..........................................................................................................................................................