DOCSLIB.ORG

Chemistry and Physics of Mechanical Hardness

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Chemistry and Physics of Mechanical Hardness CHEMISTRY AND PHYSICS OF MECHANICAL HARDNESS John J. Gilman A JOHN WILEY & SONS, INC., PUBLICATION CHEMISTRY AND PHYSICS OF MECHANICAL HARDNESS CHEMISTRY AND PHYSICS OF MECHANICAL HARDNESS John J. Gilman A JOHN WILEY & SONS, INC., PUBLICATION Copyright © 2009 by John Wiley & Sons, Inc. All rights reserved. Published by John Wiley & Sons, Inc., Hoboken, New Jersey. Published simultaneously in Canada. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, scanning, or otherwise, except as permitted under Section 107 or 108 of the 1976 United States Copyright Act, without either the prior written permission of the Publisher, or authorization through payment of the appropriate per-copy fee to the Copyright Clearance Center, Inc., 222 Rosewood Drive, Danvers, MA 01923, (978) 750-8400, fax (978) 750-4470, or on the web at www.copyright.com. Requests to the Publisher for permission should be addressed to the Permissions Department, John Wiley & Sons, Inc., 111 River Street, Hoboken, JN 07030, (201) 748-6011, fax (201) 748-6008, or online at http//www.wiley.com/go/permission. Limit of Liability/Disclaimer of Warranty: While the publisher and author have used their best efforts in preparing this book, they make no representations or warranties with respect to the accuracy or completeness of the contents of this book and specifi cally disclaim any implied warranties of merchantability or fi tness for a particular purpose. No warranty may be created or extended by sales representatives or written sales materials. The advice and strategies contained herein may not be suitable for your situation. You should consult with a professional where appropriate. Neither the publisher nor author shall be liable for any loss of profi t or any other commercial damages, including but not limited to special, incidental, consequential, or other damages. For general information on our other products and services or for technical support, please contact our Customer Care Department within the United States at (800) 762-2974, outside the United States at (317) 572-3993 or fax (317) 572-4002. Wiley also publishes its books in a variety of electronic formats. Some content that appears in print may not be available in electronic formats. For more information about Wiley products, visit our web site at www.wiley.com. Library of Congress Cataloging-in-Publication Data: Gilman, John J. (John Joseph) Chemistry and physics of mechanical hardness / John J. Gilman. p. cm. – (Wiley series on processing of engineering materials) “A Wiley-Interscience publication.” Includes bibliographical references and index. ISBN 978-0-470-22652-0 (cloth) 1. Hardness. 2. Strength of materials. I. Title. TA418.42.G55 2009 620.1′126–dc22 2008038594 Printed in the United States of America. 10 9 8 7 6 5 4 3 2 1 TABLE OF CONTENTS Preface xi 1 Introduction 1 1.1 Why Hardness Matters (A Short History) 1 1.2 Purpose of This Book 5 1.3 The Nature of Hardness 7 References 10 2 Indentation 11 2.1 Introduction 11 2.2 The Chin-Gilman Parameter 14 2.3 What Does Indentation Hardness Measure? 14 2.4 Indentation Size Effect 20 2.5 Indentation Size (From Macro to Nano) 22 2.6 Indentation vs. Scratch Hardness 23 2.7 Blunt or Soft Indenters 24 2.8 Anisotropy 24 2.9 Indenter and Specimen Surfaces 25 References 25 3 Chemical Bonding 27 3.1 Forms of Bonding 27 3.2 Atoms 28 3.3 State Symmetries 29 3.4 Molecular Bonding (Hydrogen) 31 3.5 Covalent Bonds 36 3.6 Bonding in Solids 41 3.6.1 Ionic Bonding 41 3.6.2 Metallic Bonding 43 3.6.3 Covalent Crystals 44 3.7 Electrodynamic Bonding 45 3.8 Polarizability 47 References 48 v vi TABLE OF CONTENTS 4 Plastic Deformation 51 4.1 Introduction 51 4.2 Dislocation Movement 52 4.3 Importance of Symmetry 55 4.4 Local Inelastic Shearing of Atoms 56 4.5 Dislocation Multiplication 57 4.6 Individual Dislocation Velocities (Microscopic Distances) 59 4.7 Viscous Drag 60 4.7.1 Pure Metals 61 4.7.2 Covalent Crystals 62 4.8 Deformation-Softening and Elastic Relaxation 62 4.9 Macroscopic Plastic Deformation 63 References 64 5 Covalent Semiconductors 67 5.1 Introduction 67 5.2 Octahedral Shear Stiffness 69 5.3 Chemical Bonds and Dislocation Mobility 71 5.4 Behavior of Kinks 75 5.5 Effect of Polarity 77 5.6 Photoplasticity 79 5.7 Surface Environments 80 5.8 Effect of Temperature 80 5.9 Doping Effects 80 References 81 6 Simple Metals and Alloys 83 6.1 Intrinsic Behavior 83 6.2 Extrinsic Sources of Plastic Resistance 85 6.2.1 Deformation-Hardening 85 6.2.2 Impurity Atoms (Alloying) 87 6.2.3 Precipitates (Clusters, Needles, and Platelets) 89 6.2.4 Grain-Boundaries 90 6.2.5 Surface Films (Such as Oxides) 94 6.2.6 Magnetic Domain Walls 95 6.2.7 Ferroelectric Domain-Walls 96 6.2.8 Twin Boundaries 96 References 96 7 Transition Metals 99 7.1 Introduction 99 7.2 Rare Earth Metals 101 References 101 TABLE OF CONTENTS vii 8 Intermetallic Compounds 103 8.1 Introduction 103 8.2 Crystal Structures 104 8.2.1 Sigma Phase 104 8.2.2 Laves Phases 105 8.2.3 Ni3Al 107 8.3 Calculated Hardness of NiAl 112 8.4 Superconducting Intermetallic Compounds 113 8.5 Transition Metal Compounds 115 References 116 9 Ionic Crystals 119 9.1 Alkali Halides 119 9.2 Glide in the NaCl Structure 120 9.3 Alkali Halide Alloys 123 9.4 Glide in CsCl Structure 124 9.5 Effect of Imputities 124 9.6 Alkaline Earth Fluorides 126 9.7 Alkaline Earth Sulfi des 128 9.8 Photomechanical Effects 128 9.9 Effects of Applied Electric Fields 129 9.10 Magneto-Plasticity 129 References 129 10 Metal-Metalloids (Hard Metals) 131 10.1 Introduction 131 10.2 Carbides 132 10.3 Tungsten Carbide 134 10.4 Borides 136 10.5 Titanium Diboride 137 10.6 Rare Metal Diborides 138 10.7 Hexaborides 138 10.8 Boron Carbide (Carbon Quasi-Hexaboride) 140 10.9 Nitrides 141 References 141 11 Oxides 143 11.1 Introduction 143 11.2 Silicates 143 11.2.1 Quartz 144 11.2.2 Hydrolytic Catalysis 146 11.2.3 Talc 146 11.3 Cubic Oxides 147 11.3.1 Alkaline Earth Oxides 147 viii TABLE OF CONTENTS 11.3.2 Perovskites 148 11.3.3 Garnets 150 11.3.3.1 (Y3Al5O12)—YAG 151 11.4 Hexagonal (Rhombohedral) Oxides 152 11.4.1 Aluminum Oxide (Sapphire) 152 11.4.2 Hexaboron Oxide 153 11.5 Comparison of Transition Metal Oxides with “Hard Metals” 155 References 156 12 Molecular Crystals 157 12.1 Introduction 157 12.2 Anthracene 158 12.3 Sucrose 159 12.4 Amino Acids 159 12.5 Protein Crystals 160 12.6 Energetic Crystals (Explosives) 161 12.7 Commentary 161 References 161 13 Polymers 163 13.1 Introduction 163 13.2 Thermosetting Resins (Phenolic and Epoxide) 164 13.3 Thermoplastic Polymers 165 13.4 Mechanisms of Inelastic Plasticity 166 13.5 “Natural” Polymers (Plants) 166 13.6 “Natural” Polymers (Animals) 168 References 168 14 Glasses 171 14.1 Introduction 171 14.2 Inorganic Glasses 172 14.3 Metallic Glasses 176 14.3.1 Hardness—Shear Modulus Relationship 177 14.3.2 Stable Compositions 180 References 180 15 Hot Hardness 183 15.1 Introduction 183 15.2 Nickel Aluminide versus Oxides 184 15.3 Other Hard Compounds 184 15.4 Metals 185 TABLE OF CONTENTS ix 15.5 Intermetallic Compounds 187 References 187 16 Chemical Hardness 189 16.1 Introduction 189 16.2 Defi nition of Chemical Hardness 190 16.3 Physical (Mechanical) Hardness 192 16.4 Hardness and Electronic Stability 193 16.5 Chemical and Elastic Hardness (Stiffness) 194 16.6 Band Gap Density and Polarizability 194 16.7 Compression Induced Structure Changes 195 16.8 Summary 196 References 196 17 “Superhard” Materials 197 17.1 Introduction 197 17.2 Principles for High Hardness 197 17.3 Friction at High Loads 198 17.4 Superhard Materials 199 References 200 Index 203 PREFACE For the structural applications of materials, there is no more useful measurable property than mechanical hardness. It quickly and conveniently probes the strengths of materials at various scales of aggregation. Firstly, it does this at the human scale (Brinell hardness — millimeters to centimeters). Secondly, it does so at a microscopic scale (Vickers microhardness — 1 to 100 microns). And thirdly, it does so at a “ nanoscale ” (nanoindentation — 10 to 1000 nanometers). For millenia, hardness has been used to characterize materials; for example, to describe various kinds of wood ranging from soft balsa wood to hard maple and ironwood. Mineralogists have used it to characterize differing rocks, and gemologists for the description of gems. Ceramists and metallurgists depend on it for classifying their multitude of products. Hardness does not produce a complete characterization of the strengths of materials, but it does sort them in a general way, so it is very useful for “ quality control ” ; for the development of new materials; and for developing prototypes of devices and processes. Furthermore, mechanical hardness is closely related to chemical hardness, which is a measure of chemical bond stability (reactivity). In the case of metals the connection is somewhat indirect, but nevertheless exists. The principal intention of the present book is to connect mechanical hardness numbers with the physics of chemical bonds in simple, but defi nite (quantitative) ways. This has not been done very effectively in the past because the atomic processes involved had not been fully identifi ed.
Load more

Recommended publications
  • Correlation of the Mohs's Scale of Hardness with the Vickers' S Hardness Numbers
    718 Correlation of the Mohs's scale of hardness with the Vickers' s hardness numbers. By E. WILFRED TAYLOR, C.B.E., F.R.M.S., F. Inst. P. Messrs. Cooke, Troughton & Simms, Ltd., York. [Read June 23, 1949.] INERALOGISTS have long been accustomed to describe hard- M ness with the aid of a scale devised by Friedrich Mohs, who lived from 1773 to 1839. The test is qualitative, each mineral in the scale being capable of scratching those that precede it, but the ten minerals have held their ground as a useful representative series with which it is now interesting to compare another method of estimating hard- ness. In the metallurgical world hardness is now usually expressed by means of the Vickers's hardness numbers or their equivalent, and the figures are derived from the size of the impression made by a diamond indenter in the form of a four-sided pyramid with the opposite faces worked to an included angle of 136 ~ More recently micro-hardness testers have been devised to enable minute impressions to be formed under light loads on small individual crystals of a metallic alloy, 1 and it occurred to the author to obtain hardness figures for the various types of optical glass by means of a scratch test with such an instrument. The intention was to draw a lightly loaded diamond across a polished glass surface and to measure the width of the resulting furrow. This method proved to be promising, but as an experiment a static indenter was also used, and it was dis- covered that glass was sufficiently plastic to take good impressions, so long as the load did not exceed 50 grams or thereabouts.
    [Show full text]
  • The Development of Scratch Test Methodology And
    THE DEVELOPMENT OF SCRATCH TEST METHODOLOGY AND CHARACTERIZATION OF SURFACE DAMAGE OF POLYPROPYLENE A Thesis by MIN HAO WONG Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE August 2003 Major Subject: Mechanical Engineering THE DEVELOPMENT OF SCRATCH TEST METHODOLOGY AND CHARACTERIZATION OF SURFACE DAMAGE OF POLYPROPYLENE A Thesis by MIN HAO WONG Submitted to Texas A&M University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Approved as to style and content by: Hung- Jue Sue Terry Creasy (Chair of Committee) (member) David E. Bergbreiter Dennis L. O’Neal (member) (Head of Department) August 2003 Major Subject: Mechanical Engineering iii ABSTRACT The Development of Scratch Test Methodology and Characterization of Surface Damage of Polypropylene. (August 2003) Min Hao Wong, B.S., Nanyang Technological University Chair of Advisory Committee: Dr. Hung-Jue Sue A new scratch test methodology is proposed. The new test methodology is developed based on the principles of materials science and solid mechanics, which include the consideration of material parameters, use of microscopy for image analysis and the finite element method (FEM). The consistency and reproducibility of test results are shown using a new scratch test device on two sets of neat and talc-filled polypropylene (PP) systems. Three different test conditions, i.e., linear load increase under constant rate, constant load under constant rate, and linear rate increase under constant load, have been conducted to determine the most effective, informative test conditions for evaluation of scratch resistance of polymers.
    [Show full text]
  • Scratch Test
    SCRATCH TEST AUTHOR: Ing. TOMÁŠ KADLÍČEK SUBJECT: MICROMECHANICS AND MICROSTRUCTURAL DESCRIPTION OF MATERIALS LECTURER: doc. Ing. JIŘÍ NĚMEČEK, Ph.D. AKAD. YEAR: 2014/2015 1 CONTENT INTRODUCTION ................................................................................................................. 1 1 THEORY .................................................................................................................... 2 1.1 SCRATCH TESTERS ................................................................................................ 2 1.2 SCRATCH TEST ...................................................................................................... 2 1.2.1 TESTS OF COATINGS ...................................................................................... 4 BASIC CHARACTERISTICS ........................................................................................ 4 ADHESION .............................................................................................................. 5 WEAR ..................................................................................................................... 5 SCRATCH HARDNESS HS ......................................................................................... 5 1.2.2 COHESIVE MATERIALS ................................................................................... 6 DETERMINATION OF MOHR-COULOMB PARAMETERS ......................................... 6 FRACTURE TOUGHNESS OBTAINED WITH RECTANGULAR BLADE ................. 7 FRACTURE TOUGHNESS OBTAINED
    [Show full text]
  • Abrasion Hardness, 2 Absolute Hardness, 72, 123 Activation Energy
    Index Abrasion hardness, 2 Alumina (Cont.) Absolute hardness, 72, 123 hardness (Cont.) Activation energy time effect, 140 of creep indentation creep, 234 in magnesia, 141 ion bombardment, 126 in silicon carbide, 141, 215 ISE values, 130, 259, 260-261 in tungsten carbide, 141 Knoop hardness, 86, 134, 259 of penetration, 63 pH effect, 138 of scratching, 62 water effect, 134 Adhesion of thin films, 205 Mohs number, 28 Aecheson process, 209 pendulum hardness, 28 Agglomerate toughening, 273, 275 plasticity parameter, 241 Aliovalent cations and hardening, 9 polishing agent, 45-46 AlN4 tetrahedra, 223 purity and uses, 255 Al04 tetrahedra, 223 ring crack appearance, 165 Alumina (Al20 3), 4, 255-264 scratch hardness, 29, 261 anisotropy in, 84, 256, 262 silica glass brittleness index, 188 hardness, 243 Burgers vectors, 89 modulus, 243 critical flaws in, 153, 154,259,260 toughness, 243 density, 260-261 slip systems, 89, 255 effect of pH on, 140, 262 solution hardening, 9, 262-263 effect of water on, 260 structure, 255-256 elastoplastic behavior, 49 toughness, 127, 184,257-261,278 erosion hardness, 192, 229 grain-size effect, 184, 257, 260 gamma, 262, 264 and zirconia content, 278 grain boundary Vickers hardness, 259, 260 fracture toughness, 258-259 Young's modulus, 259, 260 phases, 258 Aluminum grain-size hardness effect, 256-257 matrix for borides, 298 hardness surface hardening, 45-46 anisotropy, 81, 84, 260, 278 Vickers hardness, 46 pH effect, 262 Aluminum nitride (AlN) temperature effect, 262 hardness, 303 307 308 Index Aluminum nitride (Cont.)
    [Show full text]
  • Moh's Scale of Relative Hardness
    Moh’s scale of relative hardness MOH’S SCALE OF RELATIVE HARDNESS The Moh’s scale is a rating system for hardness that ranges from 1 to 10 with 1 being the softest and 10 being the hardest. Moh took ten well-known and easily available minerals and arranged them in order of their ‘scratch hardness’. If a specimen to be tested can be scratched by a known mineral from this list, the scratched specimen is softer than that mineral. Likewise, if the test specimen can scratch a mineral on the list, then it is harder than that mineral. The ten minerals are as follows: Moh hardness Mineral 1 Talc 2 Gypsum 3 Calcite 4 Fluorite 5 Apatite 6 Feldspar 7 Quartz 8 Topaz 9 Corundum 10 Diamond This scale should be more accurately called a ‘table’ because it is not to scale. For example, the difference in hardness between talc and gypsium is not the same as the difference in hardness between gypsum and calcite. Therefore it is just an ordered list. Moh hardness of some common materials are as follows: Material Moh hardness Fingernail 2.5 Copper penny 3 Steel knife blade 5.5 - 6 Window glass 5.5 - 6 Hardened steel file 7 Emery cloth 8 - 9 www.gritco.com There are many different aspects of a material that can be considered as a measure of hardness such as resistance to scratching, indentation, bending, abrasion or fraction. It is very easy to confuse durability or toughness with hardness. A simple example is the difference between a glass ball and a rubber ball.
    [Show full text]
  • Some Expected Mechanical Characteristics of Lunar Dust: a Geological View
    Some Expected Mechanical Characteristics of Lunar Dust: A Geological View Doug Rickman1 and Kenneth W. Street2 1 National Space Science and Technology Center, NASA Marshall Space Flight Center, Huntsville, AL 35805 USA 2 Tribology and Surface Science, NASA Glenn Research Center, Cleveland, OH 44135 USA 256-961-7889, [email protected] Abstract. The engineering properties of the lunar regolith reflect aspects of the original parent rock and the consequences of hypervelocity meteor bombardment. Compared to the Earth the geologic nature of the lunar regolith is quite distinct. On scales relevant to machinery, heterogeneity with respect to size and composition is much higher. But the total range in composition is much more restricted. Both facts have implications for predictions of properties, such as abrasion, which will be required by design engineers for constructing equipment for lunar use. Abrasion is related to hardness and hardness is a commonly measured property for both minerals and engineering materials. Although different hardness scales are routinely employed for minerals and engineering materials, a significant amount of literature is available relating the two. In this paper we discuss how to relate hardness to abrasion for the design of lunar equipment. We also indicate how abundant the various mineral phases are and typical size distributions for lunar regolith. Keywords: Lunar regolith, mineralogy, engineering materials, abrasion. PACS: 89, 89.20.Bb. INTRODUCTION The initial composition of the lunar crust is believed (Wilhelms, McCauley, and Trask, 1987; Jolliff, et al., 2006; Heiken, Vaniman, and French, 1991) to have been dominated by intrusive igneous rock with an average composition in the range of norite (Le Maitre, 2005).
    [Show full text]
  • Scratch Resistance
    SCRATCH RESISTANCE Glazed tiles intended for flooring are also subjected to mechanical aggressions in the form of gouging owing to the movement, under pressure, of materials with sharp edges that are harder than the glaze that forms the tile surface. Hence the consideration of scratch resistance in the past as a fundamental characteristic for all glazed tiles intended for flooring. However, the subjectivity of the test method set out in standard UNE 67-101 (1992) has resulted in the elimination of this characteristic in standard EN 14411. Since it is a characteristic that is still provided by most manufacturers, it is interesting to have it as complementary information to the resistance to surface abrasion. A scratch hardness of 6 provides a certain assurance of scratch resistance in flooring subject to intermediate and high traffic. MOHS SCALE OF HARDNESS STANDARD EN 67-101-92 Mineral Mohs hardness TALC 1 GYPSUM 2 CALCITE 3 FLUORITE 4 APATITE 5 ORTHOCLASE 6 QUARTZ 7 TOPAZ 8 CORUNDUM 9 DIAMOND 10 Scientific-technical aspects Hardness is defined as the resistance that a material opposes to being penetrated by another material, this being a property innate to the nature of the material. To measure this, in homogeneous materials, the Vickers microhardness test has been used, which consists of indentation by an inverted diamond pyramid, of standard dimensions, in the surface of a homogeneous material, applying a given load for a period of time. Physico-chemical characteristics 1 Scratch resistance The effect of the indentation is then evaluated because, since a track is produced by pressure, there is an elastic strain and a plastic deformation, though the physical mechanisms underlying such behaviour are still insufficiently understood.
    [Show full text]
  • On the Nature of Cemented Carbide Wear in Rock Drilling
    Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology 964 On the Nature of Cemented Carbide Wear in Rock Drilling BY ULRIK BESTE ACTA UNIVERSITATIS UPSALIENSIS UPPSALA 2004 !""# $"%$& ' ' ' ( ) * + +) , ) !""#) - . ' / / 0 1 2 ) 3 ) 45#) # ) ) 6,. 4$7&&#7&4847" 0/9/ ' + ) * : ' ;' 0/7 < ;' / < ' 2 ) * + ' '' 2 ) * ' + ' ' = 27 ) 3 ' 2 + ' + ) * ' ) * '' ' ' + *> + ) + : ' + 2 ? ' ' ) 6 + ' 2 + ' ' ' + ) @ + ' + '' 2 '' 2 ' ) ' 2 ' 2 ' 2 + + ' + ' 2 ) + 2 2 ! " # " !$ %&'" " #()%* +* " A 2 , !""# 6. $$"#7!8!B 6,. 4$7&&#7&4847" % %%% 7#!!8 ; %99 )2)9 C D % %%% 7#!!8< To… …my great surprise. List of Papers included in the thesis I Micro scale hardness distribution of rock types related to rock drill wear. U. Beste and S. Jacobson, Wear 254 (2003), Issue 11, p. 1147-1154. II Micro scratch evaluation of rock types – a means to comprehend rock drill wear, U. Beste, A. Lundvall, S. Jacobson, Tribology International (Feb 2004), vol. 37, Issue 2, p. 203-210 III Friction between a cemented carbide rock drill button and different rock types, U.
    [Show full text]
  • Some Expected Mechanical Characteristics of Lunar Dust: a Geological View
    Some Expected Mechanical Characteristics of Lunar Dust: A Geological View Doug Rickman 1 and Kenneth W. Street 2 1 National Space Science and Technology Center, NASA Marshall Space Flight Center, Huntsville, AL 35805 USA 2 Tribology and Surface Science, NASA Glenn Research Center, Cleveland, OH 44135 USA 256-961-7889, [email protected] Abstract. The engineering properties of the lunar regolith reflect aspects of the original parent rock and the consequences of hypervelocity meteor bombardment. Compared to the Earth the geologic nature of the lunar regolith is quite distinct. On scales relevant to machinery, heterogeneity with respect to size and composition is much higher. But the total range in composition is much more restricted. Both facts have implications for predictions of properties, such as abrasion, which will be required by design engineers for constructing equipment for lunar use. Abrasion is related to hardness and hardness is a commonly measured property for both minerals and engineering materials. Although different hardness scales are routinely employed for minerals and engineering materials, a significant amount of literature is available relating the two. In this paper we discuss how to relate hardness to abrasion for the design of lunar equipment. We also indicate how abundant the various mineral phases are and typical size distributions for lunar regolith. Keywords: Lunar regolith, mineralogy, engineering materials, abrasion. PACS: 89, 89.20.Bb . INTRODUCTION The initial composition of the lunar crust is believed (Wilhelms, McCauley, and Trask, 1987; Jolliff, et al., 2006; Heiken, Vaniman, and French, 1991) to have been dominated by intrusive igneous rock with an average composition in the range of norite (Le Maitre, 2005).
    [Show full text]
  • Industrial Minerals, Gems and Minor Metals in the Yukon I
    Industrial Minerals, Gems and Minor Metals in the Yukon i INDUSTRIAL MINERALS, GEMS AND MINOR METALS IN THE YUKON Compiled by G.V. White, P. Geo. GV White Resources Ltd., Whitehorse, Yukon, Canada ii Industrial Minerals, Gems and Minor Metals in the Yukon Industrial Minerals, Gems and Minor Metals in the Yukon iii ii Industrial Minerals, Gems and Minor Metals in the Yukon Industrial Minerals, Gems and Minor Metals in the Yukon iii PREFACE PRE iv Industrial Minerals, Gems and Minor Metals in the Yukon Industrial Minerals, Gems and Minor Metals in the Yukon v iv Industrial Minerals, Gems and Minor Metals in the Yukon Industrial Minerals, Gems and Minor Metals in the Yukon v This paper follows a similar format used by D. Downing in his 1993 report entitled ‘Industrial Minerals and Minor Metals and Their Potential for Development in the Yukon’. The report’s objective is to encourage and inform mineral explorationists about industrial minerals and their potential for development in the Yukon. A discussion about gemstones and minor metals is also included, because of the potential for economic deposits to occur in the territory. Primary sources of information compiled in this report are from government and industry commodity forecast reports, geological bulletins, papers, open file reports, industry summary reports, company property reports and maps, industrial mineral trade magazines, and through personal communications. Information about documented Yukon industrial mineral occurrences was extracted from the most recent Yukon Minfile database (Yukon Minfile 2001) and from company reports and assays. For organizational purposes and to allow for easier reading, this report is divided into five separate chapters.
    [Show full text]
  • The Concept of Hardness As Applied to Mineral Aggregates J
    The Concept of Hardness As Applied to Mineral Aggregates J. E. GRAY, Engineering Director, and F. A. RENNINGER, Geologist, National Crushed Stone Association A historical review is given of the soft particle requirements in specifications showing, with the development of the scratch hardness test, a broadening of the application of the test without sufficient supporting data to indicate that the test measures a property which actually affects performance. Originally soft­ ness was used to indicate the presence of unsound material which caused pop-outs in concrete. Softness as measured by the scratch hardness test is considered to be a measure of deleterious material in aggregate and is a specification require­ ment without association to any other property and without suf­ ficient information to show that softness, per se, is in fact a deleterious property of aggregate. Data are presented that relate the scratch hardness test in terms of Mohs hardness scale which indicates that both procedures may classify min­ erals but not rocks of variable mineral composition. Finally, data are presented which demonstrate that aggregate which fails the scratch hardness test may make strong, sound, durable concrete. In light of the philosophy of materials testing, the historical review, and the test data submitted, it is suggested that the present CO!J.Cept of aggregate hardness be reconsidered and re-evaluated. •A DICTIONARY might define the word hardness as "the state of being hard" or "the state of being firm or unyielding." That same dictionary, if it were scientifically ori­ ented, might go even further and define hardness as "that quality of a mineral which resists scratching." Both definitions, that of being firm or unyielding and that of scratchability, relate to the concept of hardness as it is currently applied to mineral aggregates.
    [Show full text]
  • Making Gemstone Jewelry
    Making Gemstone Jewelry Gemstones and metal jewelry have been beautiful partners for thousands of years. The gemstone cuts have changed through the centuries, as have the jewelry design styles, but now as then, gemstones add beauty, value, and color to metal jewelry designs in a way that nothing else can. There are literally hundreds of different gemstones with more being discovered occasionally, even in modern times. Because they all have different qualities, specifically qualities related to durability like hardness, cleavage, and fracture, not all gemstones are suitable for use in jewelry. Some gems are more suitable for gently worn jewelry, such as earrings and pendants, than for jewelry that can receive hard knocks during daily wear, such as bracelets and rings. It’s important to understand a gemstone’s durability and consider it as you are making gemstone jewelry. Let’s take a closer look at hardness. To fully understand a gemstone’s hardness–and get an idea of its suitability for jewelry designs–you need to understand the Mohs hardness scale. Learn more about the scale below from jewelry experts Tom and Kay Benha2323m. Mohs’ Hardness for Gemstones By Tom and Kay Benham, Contributing Editors, Lapidary Journal Jewelry Artist Beginning rockhounds and jewelry makers are often confused by the Mohs hardness scale for rocks and gems. The Mohs hardness scale was set up in the early 1800s by mineralogist Friedrich Mohs, who selected 10 well-known minerals and numbered them in order of scratch hardness, such that a mineral will scratch all minerals having a lower hardness number. It served the purposes of comparison–but because it is a non-linear scale, it does not provide a true indication of the relationship of the various hardnesses.
    [Show full text]