Publication Date

3-26-2021

Department

Ames Laboratory

Campus Units

Ames Laboratory

OSTI ID+

1781337

Report Number

IS-J 10466

DOI

10.1002/9781119951438.eibc2076.pub2

Journal Title

Encyclopedia of Inorganic and Bioinorganic Chemistry

Abstract

Materials with superior hardness can be categorized as ultrahard (Vickers hardness, Hv ≥ 80 GPa) and superhard (Hv ≥ 40 GPa). These materials are commonly used as cutting tools and abrasives in the machining and manufacturing industries. With its extreme hardness, diamond is the best known and most used ultrahard material for industrial applications. However, it is ineffective at cutting and drilling ferrous alloys due to diamond's high reactivity with iron and poor thermal stability in air. Additionally, the synthesis of diamond requires both high pressure (HP) and high temperature, making it an expensive process. These limitations have driven the search for alternative superhard materials that are capable of cutting steels and other materials at lower costs. This article reviews the concept of hardness and summarizes advancements in the synthesis and mechanical properties of hard materials. It begins with a review of methods to measure hardness, adding HP diffraction methods to more conventional hardness measurements. It then considers new ultrahard materials that exist within the B–C–N ternary system, with hardness approaching diamond but improved chemical stability. Finally, it surveys superhard nitrides, oxides, and borides as potential alternative materials, focusing on transition metal boride systems where the synthesis can be readily achieved at ambient pressure and scaled for industrial applications. We hope that this article serves as an overview of hard materials and guide for the comparison of data reported in the literature.

DOE Contract Number(s)

AC02-07CH11358

Language

en

Department of Energy Subject Categories

36 MATERIALS SCIENCE

Publisher

Iowa State University Digital Repository, Ames IA (United States)

Available for download on Saturday, March 26, 2022

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