Advances in Ceramic Armor XI

Advances in Ceramic Armor XI

A Collection of Papers Presented at the39th International Conference on

Advanced Ceramics and CompositesJanuary 25–30, 2015

Daytona Beach, Florida

Editor

Jerry C. LaSalvia

Volume Editors

Jingyang WangSoshu Kirihara

Copyright © 2016 by The American Ceramic Society. All rights reserved.

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Preface vii

Introduction ix

TNO’s Research on Ceramic Based Armor 1Erik Carton, Geert Roebroeks, Jaap Weerheijm, André Diederen, and

Manfred Kwint

Investigation of the Kinetic Energy Characterization of Advanced 19

Ceramics

Tyrone L. Jones

Predicting the Light Transmittance of Multilayer Transparent 29

ArmorBrandon S. Aldinger

Operator Training and Performance Measurement for 41

Nondestructive Testing of Ceramic ArmorK. F. Schmidt, J. R. Little, W. H. Green, L. P. Franks, and W. A. Ellingson

From Micron-Sized Particles to Nanoparticles and Nanobelts: 51

Structural Non-Uniformity in the Synthesis of Boron Carbide by

Carbothermal Reduction Reaction Paniz Foroughi and Zhe Cheng

Nanocrystalline Boron Carbide Powder Synthesized Via 63

Carbothermal Reduction ReactionSaid M. El-Sheikh, Yasser M. Z. Ahmed, Emad M. M. Ewais,

Asmaa Abd-El-Baset Abd Allah, and Said Anwar

Synthesis and Crystallization Behavior of Amorphous Boron 75

Nitride Metin Örnek, Chawon Hwang, Vladislav Domnich, Steven L. Miller,

Willam E. Mayo, and Richard A. Haber

v

Contents

c-BN Seeding Effect on the Phase Transition of a-BN(OC) 83

CompoundChawon Hwang, Metin Örnek, Vladislav Domnich, William E. Mayo,

Steve L. Miller, and Richard A. Haber

Screening of Silicon Precursors for Incorporation into Boron 93

CarbideAnthony Etzold, Richard Haber, and William Rafaniello

Processing of Boron Rich Boron Carbide 99Tyler Munhollon, Rich Haber, and William Rafaniello

Reaction Bonded SiC/Diamond Composites: Properties and 111

Impact Behavior in High Strain Rate ApplicationsS. Salamone, M. Aghajanian, S.E Horner, and J.Q. Zheng

Influence of Powder Oxygen Content on Silicon Carbide 119

Microstructure and PropertiesV. DeLucca and R. A. Haber

Preparation, Characterization and Development of TiB2 Hard 131

Ceramic Materials Azmi Mert Celik, Richard A. Haber, Kanak Kuwelkar, and William Rafaniello

Improving Fracture Toughness of Alumina with Multi-Walled 137

Carbon Nanotube and Alumina Fiber ReinforcementsJ. Lo, R. Zhang, B. Shalchi-Amirkhiz, D.Walsh, M. Bolduc, S. Lin, B. Simard,

K. Bosnick, M. O’Toole, A. Merati, and M. Bielawski

Author Index 147

vi · Advances in Ceramic Armor XI

I had the pleasure of being the lead organizer for the 13th Armor Ceramics Sympo-sium in 2015 at the 39th International Conference on Advanced Ceramics andComposites. I am very grateful for the guidance and support that was provided byJeff Swab, Andy Wereszczak, and the organizing committee in putting this sympo-sium together. Consistent with the history of this symposium, we strived to create aprogram that would foster discussion and collaboration between researchers fromaround the world in academia, government, and industry on various scientific issuesassociated with the topic of armor ceramics.

The 2015 symposium consisted of approximately 68 invited, contributing, andposter presentations from the international scientific community in the areas of syn-thesis & processing, manufacturing, materials characterization, testing & evalua-tion, quasi-static & dynamic behavior, modeling, and application. In addition, be-cause of their importance for the foreseeable future, this symposium also hadspecial focused topic sessions on Advanced Materials Characterization, Intergranu-lar Films, and ceramic armor research by the Netherlands Organisation for AppliedScientific Research (TNO). Based on feedback from attendees, the 2015 sympo-sium was a success, and the manuscripts contained in these proceedings are fromsome of the presentations that comprised the 13th edition of the Armor CeramicsSymposium.

On behalf of Jeff Swab and the organizing committee, I would like to thank allof the presenters, authors, session chairs, and manuscript reviewers for their effortsin making this symposium and the associated proceedings a success. I would alsoespecially like to thank Andy Wereszczak, Vlad Domnich, Mike Golt, Steve Kil-czewski, Kris Behler, Victoria Blair, Jonathan Ligda, Jim McCauley, and NitinDaphalapurkar for hosting and chairing the symposium when we were unable todue to remnant effects of Sequestration. Last, but not least, I would like to recog-nize Marilyn Stoltz and Greg Geiger of The American Ceramic Society, for theirsupport and tireless efforts without which the success of this symposium would notbe possible.

JERRY C. LASALVIA

Symposium Chair, Armor Ceramics

vii

Preface

ix

Introduction

This CESP issue consists of papers that were submitted and approved for the pro-ceedings of the 39th International Conference on Advanced Ceramics and Compos-ites (ICACC), held January 25–30, 2015 in Daytona Beach, Florida. ICACC is themost prominent international meeting in the area of advanced structural, functional,and nanoscopic ceramics, composites, and other emerging ceramic materials andtechnologies. This prestigious conference has been organized by the EngineeringCeramics Division (ECD) of The American Ceramic Society (ACerS) since 1977.

The 39th ICACC hosted more than 1,000 attendees from 40 countries and over800 presentations. The topics ranged from ceramic nanomaterials to structural relia-bility of ceramic components which demonstrated the linkage between materialsscience developments at the atomic level and macro level structural applications.Papers addressed material, model, and component development and investigatedthe interrelations between the processing, properties, and microstructure of ceramicmaterials.

The 2015 conference was organized into the following 21 symposia and ses-sions:

Symposium 1 Mechanical Behavior and Performance of Ceramics and Composites

Symposium 2 Advanced Ceramic Coatings for Structural, Environmental, and Functional Applications

Symposium 3 12th International Symposium on Solid Oxide Fuel Cells (SOFC): Materials, Science, and Technology

Symposium 4 Armor Ceramics: Challenges and New DevelopmentsSymposium 5 Next Generation Bioceramics and BiocompositesSymposium 6 Advanced Materials and Technologies for Energy Generation and

Rechargeable Energy StorageSymposium 7 9th International Symposium on Nanostructured Materials and

Nanocomposites Symposium 8 9th International Symposium on Advanced Processing &

Manufacturing Technologies for Structural & Multifunctional Materials and Systems (APMT), In Honor of Prof. Stuart Hampshire

Symposium 9 Porous Ceramics: Novel Developments and ApplicationsSymposium 10 Virtual Materials (Computational) Design and Ceramic GenomeSymposium 11 Advanced Materials and Innovative Processing ideas for the

Industrial Root TechnologySymposium 12 Materials for Extreme Environments: Ultrahigh Temperature

Ceramics (UHTCs) and Nanolaminated Ternary Carbides and Nitrides (MAX Phases)

Symposium 13 Advanced Ceramics and Composites for Sustainable Nuclear Energy and Fusion Energy

Focused Session 1 Geopolymers, Chemically Bonded Ceramics, Eco-friendly and Sustainable Materials

Focused Session 2 Advanced Ceramic Materials and Processing for Photonics andEnergy

Focused Session 3 Materials Diagnostics and Structural Health Monitoring of Ceramic Components and Systems

Focused Session 4 Additive Manufacturing and 3D Printing Technologies Focused Session 5 Single Crystalline Materials for Electrical, Optical and Medical

ApplicationsFocused Session 6 Field Assisted Sintering and Related Phenomena at High

TemperaturesSpecial Session 2nd European Union-USA Engineering Ceramics Summit Special Session 4th Global Young Investigators Forum

The proceedings papers from this conference are published in the below sevenissues of the 2015 CESP; Volume 36, Issues 2-8, as listed below.

Mechanical Properties and Performance of Engineering Ceramics and Composites X, CESP Volume 36, Issue 2 (includes papers from Symposium 1)Advances in Solid Oxide Fuel Cells and Electronic Ceramics, CESP Volume 36,Issue 3 (includes papers from Symposium 3 and Focused Session 5)Advances in Ceramic Armor XI, CESP Volume 36, Issue 4 (includes papers from Symposium 4)Advances in Bioceramics and Porous Ceramics VIII, CESP Volume 36, Issue 5 (includes papers from Symposia 5 and 9)Advanced Processing and Manufacturing Technologies for Nanostructured and Multifunctional Materials II, CESP Volume 36, Issue 6 (includes papers from Symposia 7 and 8 and Focused Sessions 4 and 6)Ceramic Materials for Energy Applications V, CESP Volume 36, Issue 7 (includes papers from Symposia 6 and 13 and Focused Session 2)Developments in Strategic Ceramic Materials, CESP Volume 36, Issue 8 (includes papers from Symposia 2, 10, 11, and 12; from Focused Sessions 1 and 3); the European-USA Engineering Ceramics Summit; and the 4th Annual Global Young Investigator Forum

The organization of the Daytona Beach meeting and the publication of these pro-ceedings were possible thanks to the professional staff of ACerS and the tireless

x · Advances in Ceramic Armor XI

dedication of many ECD members. We would especially like to express our sincerethanks to the symposia organizers, session chairs, presenters and conference atten-dees, for their efforts and enthusiastic participation in the vibrant and cutting-edgeconference.

ACerS and the ECD invite you to attend the Jubilee Celebration of the 40th In-ternational Conference on Advanced Ceramics and Composites (http://www.ceram-ics.org/daytona2016) January 24-29, 2016 in Daytona Beach, Florida.

To purchase additional CESP issues as well as other ceramic publications, visitthe ACerS-Wiley Publications home page at www.wiley.com/go/ceramics.

JINGYANG WANG, Institute of Metal Research, Chinese Academy of Sciences, Shenyang, China

SOSHU KIRIHARA, Osaka University, Osaka, Japan

Volume EditorsJuly 2015

Advances in Ceramic Armor XI · xi

1

TNO’s RESEARCH ON CERAMIC BASED ARMOR

Erik Carton, Geert Roebroeks, Jaap Weerheijm, André Diederen and Manfred Kwint Group Explosions, Ballistics and Protection, TNO P.O. Box 45, Rijswijk, The Netherlands

ABSTRACT Several specially designed experimental techniques including an alternative test method

have been developed for the evaluation of ceramic based armor. Armor grade ceramics and a range of combined materials have been tested using 7.62 AP rounds. Using the energy method [12] the dwell-time and total energy absorbed from the AP core were determined. In additional tests time-resolved fracturing of the ceramic tile (fragments) was recorded using high-speed video at one million frames per second. Also the particle size distribution of the fragments were measured in order to determine the total fracture surface area. The information provided by the results of all tests has resulted in an energy-based engineering model that allows calculation of the dwell-time, erosion and residual velocity of an AP-core. The model predicts the mass and velocity of residual AP cores rather well assuming a failure period during which the intact ceramic material transfers into a massively broken medium. The model does not require detailed mechanical properties of the ceramic materials. This reflects the difficulty within the ceramic armor research community to find a relation between mechanical properties and ballistic efficiency of armor ceramics. The developed engineering model creates a renewed understanding of the relevant phenomena, that could explain the ballistic efficiency of ceramic armor.

INTRODUCTION

Over the last years TNO’s Laboratory for Ballistic Research has focused its R&D on the subject of armor ceramics, as a component of an armor system, as well as on ceramic based armor; a combination of ceramic and other materials together forming an armor system. The optimization of ceramic based armor systems is targeted by the armor community to obtain more weight efficient protection. However, armor ceramics are still not very well understood, hence there may still be a lot to gain if one can determine the main mechanisms that occur during the short interaction time between a high speed projectile and a ceramic-based armor. TNO’s research has been limited to 7.62 AP rounds and therefore is mainly focused on body-armor applications, however the scope will be expanded to vehicle armor in the coming years.

Generally speaking ceramics are an effective class of armor materials as they can both erode a hard projectile (core), hence change the nose shape and reduce its mass, and project the impact forces over an area much wider than the projectile diameter. The latter will reduce stress by spreading forces exerted on the backing material, preventing its local failure thereby allowing a large volume of backing material to be involved in the projectile-target interaction.

Over the years relationships between the mechanical properties and the ballistic efficiency of armor grade ceramics have been searched for. The unique combination of mechanical properties of ceramics like high hardness, compressive strength, stiffness and relative low density are frequently mentioned to rationalize the use of ceramics in armor. However, even after decades of use the relation between mechanical properties and ballistic (protection) efficiency is not fully understood. This may be explained by also considering some other relevant mechanical properties of ceramic materials like their modest tensile strength and brittle fracture behavior. This combination of mechanical properties results in early failure and negligible energy dissipation by fracturing of ceramic materials. It is the main reason ceramics

2 · Advances in Ceramic Armor XI

TNO’s Research on Ceramic Based Armor

are not used stand-alone in armor applications. Ceramics generally are supported by a backing material that is ductile and capable to absorb (residual kinetic) energy. Often metal plates or polymer fiber materials (like fabrics and composite) are used as backing material in armor systems. Hence, armor ceramics are often tested in combination with a backing material that influences the projectile-target interaction. This influence complicates the search for a unique relation between a mechanical property of the ceramic and its ballistic efficiency [1]. To complicate things further, the projectile-target interaction not only depends on intrinsic material properties of the ceramic and its backing material. Many researchers have shown that extrinsic properties, like tile dimensions, pre-stressing and confinement also have a large influence on the ballistic behavior of a ceramic-based armor system [2-5].

Figure 1 shows a schematic representation of the impact of a core of a bullet with a (bare) ceramic tile. The ceramic has high enough compressive strength to initially withstand the dynamic loading by the impacting projectile (a high strength core with conical or ogive nose shape). Hence, the first interaction phase is dwell; the interface velocity between projectile and ceramic is zero (U=0). The tail of the projectile still has the impact velocity (V), thus the length of the projectile will reduce with a velocity V-U=V. As an AP core consists of a brittle material, the failure strain is very low resulting in erosion rather than deformation of the core material. In the second image of figure 1, the eroded fragments/particles of the projectile nose can be seen to spray from the high pressure impact area below the projectile. The ceramic tile itself does not yield, and only responses by bending generating a linear strain distribution over the tile thickness inducing a compressive stress at the strike-face and a tensile stress at the rear of the tile. During the dwell phase the ceramic suffers from impact damage and/or erosion on the strike-face by the radial movement of the eroding projectile, as well as internal failure by comminution, micro- and macro-cracks. The internal damage of the ceramic tile is shown in yellow in figure 1. At a certain moment the internal damage has propagated throughout the tile thickness. This allows a localized flow of fragments and formation of a conical plug. From this moment on, the ceramic can flow axially reducing the dynamic loading (as U>0) finally eliminating the erosion of the projectile when U=Vr, with Vr the residual velocity of the projectile. This transition in penetration velocity (from zero to U=Vr) marks the end of the dwell phase (tDwell,end). The axial flow of fragments can be seen at the rear of the tile as this initiates an out-of-plane movement resulting in a fragment cloud that is pushed out by the residual projectile (with mass mr and velocity Vr).

Although it has not been possible to conclusively determine a relation between mechanical properties and ballistic efficiency for ceramics, one material requirement has been identified to play an important role in the ballistic efficiency of armor ceramics: hardness or compressive strength. In order to function well, the hardness should be above a minimal value which depends on the strength and velocity of the projectile to be stopped. The relevant projectile part is normally the core of an armor piercing munition type. Jacket and filler materials of bullets are relatively soft/weak materials and are easily stripped from the core in an early stage of the interaction. Their fragments and particles mainly flow away radially over the strike-face of the ceramic armor, leaving only the core to interact with the armor. Core materials are, with increasing hardness: mild steel, tungsten heavy alloy (WHA), hardened steel and cemented carbide (WC/Co). In order to initiate a dwell-phase upon impact on its strike-face the ceramic should have a minimal compressive strength (Rt) which is related to the hardness of the ceramic (a first approximation of this compression strength is Rt=Hv/2) [6]. The minimal strength requirement can be rationalized using the Tate-relation (or modified Bernouilli equation) [7]:

½ p (V U)2 + Yp = ½ t U2 + Rt (1)

Advances in Ceramic Armor XI · 3

TNO’s Research on Ceramic Based Armor

In this relation Rt represents the effective compressive strength of the ceramic target and Yp is the strength of the projectile (core) material. V is the velocity of the tail of the projectile, while U is the velocity of its front (nose), hence U is equal to the velocity of the interface.

Figure 1. Schematic representation of the projectile-target interaction of a ceramic tile

During the dwell phase the nose of the projectile is stopped on the strike-face (hence U=0) and its dynamic loading is defined by the interface stress:

P = ½ p V2 + Yp (2)

If the ceramic compressive strength is high enough (Rt>P) it can withstand this dynamic loading of the impacting projectile (at least temporary). As the core of the projectile has (by far) the highest strength of its components, Yp is only determined by the strength of the core of a bullet. A hardened steel projectile with a strength of Y=2 GPa impacting a ceramic at 1000 m/s will exert a dynamic pressure of about 6 GPa during the dwell phase (U=0). This means that a ceramic tile able to withstand this pressure should have a compressive strength Rt > 6 GPa. In order to induce a dwell-phase for a similar impact of a cemented carbide ( = 15.000 kg/m3) the ceramic should have a compressive strength of at least 10 GPa.

Ductility parameter Horii and Nemat-Nasser [20] describe a unit-less ductility parameter of a material

surrounding a flaw with half-size c: = KIC / ( c)1/2 (3) Where is the shear strength and KIC the fracture toughness of the material. The importance of ductility (or the inverse of brittleness) to ballistic performance was outlined by LaSalvia et al. [21, 22] using this ductility parameter . D-value

The D-value is a figure-of-merit for the ballistic energy absorption rate ability for ceramics. It is derived from an energy ratio during a static indentation process (e.g. hardness measurement) [11]. The indentation of a ceramic involves two aspects; inelastic deformation, resulting in a measurable residual indent, and fracture resulting in a number of cracks surrounding the residual indent. The energy dissipated in an inelastic zone with (residual indent) size a is approximately Ya3

, with Y the yield-stress (strength) of the material. Normally Y is proportional with hardness (H) [6], hence the inelastic deformation energy is on the order of Ha3.