Nanomechanics of Materials and Structures (eBook)

P. M. Anderson, Tze-jer Chuang, S. Hsieh, M.-K. Wu (Herausgeber)

eBook Download: PDF

2006 | 2006
XVIII, 324 Seiten
Springer Netherlands (Verlag)
978-1-4020-3951-5 (ISBN)

Infos

This book is derived from the proceedings of the International Workshop on Nanomechanics held at Asilomar Conference Grounds in Pacific Grove, California on July 14-17, 2004. Approximately 70 leading experts from academia, government and industrial sectors in semiconductors, computers, communication, information technology, defense, energy, transportation and aerospace attended the Workshop (see the workshop photo taken on July 16, 2004). The main objective was to convene leading researchers in the nanotechnology community to assess the current state-of-the-art and disseminate recent progress, critical issues, barriers to applications, and directions for future research in nanomechanics. Miniaturization of structural components and functional devices such as electronic, optical, mechanical and electric-magnetic parts has been a recent trend, and the pace has accelerated over the past few years. Advances in micromanufacturing, semiconductor processing (e.g., etching, lithography, grafting, etc.), sensors, actuators and microprocessors have opened up a revolutionary path to the development of new technologies such as micro-electro-mechanical systems (MEMS), nano-electro-mechanical systems (NEMS), micro-engines, smart structures, smart controllers, lab-- a-chip devices, and even bio-medical sensing devices which can detect, analyze, decide and activate appropriate functions in real time. The above-mentioned devices, structures, or systems, have one issue in common. In order to perform their assigned functions, they must maintain their structural integrity and be reliable and durable during their entire designed service life. Thus, strength, durability, and time-dependent mechanical property degradation are major concerns for design engineers and device manufacturers, even though the parts are designed for electronic, magnetic, optical or other functions.

Inhalt

Table of Contents 5
PREFACE 9
SUMMARY OF GROUP DISCUSSIONS 18
NANO MECHANICS/MATERIALS RESEARCH 30
AN AB-INITIO STUDY OF MECHANICAL BEHAVIOR FOR NANORODS 40
PHASE FIELD MODELING OF SOLIDIFICATION AND MELTING OF A CONFINED NANO-PARTICLE 50
FRICTION-INDUCED NUCLEATION OF NANOCRYSTALS 61
MODELING OF CARBON NANOTUBES AND THEIR COMPOSITES 71
FRACTURE NUCLEATION IN SINGLE-WALL CARBON NANOTUBES: The Effect of Nanotube Chirality 94
MULTISCALE MODELING OF A GERMANIUM QUANTUM DOT IN SILICON 104
NANOMECHANICS OF BIOLOGICAL SINGLE CRYSTALS 114
NANO/MICRO FLUIDIC SYSTEMS 124
MECHANICAL CHARACTERIZATION OF A SINGLE NANOFIBER 135
ATOMISTIC STUDIES OF FLAW TOLERANT NANOSCALE STRUCTURAL LINKS IN BIOLOGICAL MATERIALS 152
ATOMIC SCALE MECHANISMS OF STRESS PRODUCTION IN ELASTOMERS 173
FABRICATION AND SIMULATION OF NANOSTRUCTURES ON SILICON BY LASER ASSISTED DIRECT IMPRINT TECHNIQUE 193
STRUCTURE AND STRESS EVOLUTION DUE TO MEDIUM ENERGY ION BOMBARDMENT OF SILICON 202
MECHANICS OF NANOSTRUCTURES 210
RESIDUAL STRESSES IN NANOFILM/ SUBSTRATE SYSTEMS 215
NANOMECHANICS OF CRACK FRONT MOBILITY 226
FINITE TEMPERATURE COUPLED ATOMISTIC/ CONTINUUM DISCRETE DISLOCATION DYNAMICS SIMULATION OF NANOINDENTATION 233
STATIC ATOMISTIC SIMULATIONS OF NANOINDENTATION AND DETERMINATION OF NANOHARDNESS 243
ELECTRIC FIELD-DIRECTED PATTERNING OF MOLECULES ON A SOLID SURFACE 252
DYNAMICS OF DISLOCATIONS IN THIN COLLOIDAL CRYSTALS 262
MESOSCOPIC LENGTH SCALES FOR DEFORMED NANOSTRUCTURES 269
ROUGH SURFACE PLASTICITY AND ADHESION ACROSS LENGTH SCALES 282
MODELING THE EFFECT OF TEXTURE ON THE DEFORMATION MECHANISMS OF NANOCRYSTALLINE MATERIALS AT THE ATOMISTIC SCALE 293
MODELING THE TRIBOCHEMICAL ASPECTS OF FRICTION AND GRADUAL WEAR OF DLC FILMS 302
SUBJECT INDEX 312
AUTHOR INDEX 315

Textauszug

FRICTION-INDUCED NUCLEATION OF NANOCRYSTALS (p. 45-46)

S. Guruzu, G. Xu, and H. Liang
Department of Mechanical Engineering, Texas A&,M University, College Station, TX 77843- 3123

Abstract: Experimental investigation of friction induced nucleation of nanocrystals was conducted. A series of interfacial interactions were experimentally examined, including pressing, light sliding, and heavy sliding. Results showed that only under a certain sliding conditions, nucleation of crystalline features were formed. Compressing along with heavy sliding caused either melting or severe wear. This preliminary research demonstrated the feasibility of using a friction-stimulation process combined with phase transformation to generate nanostructured materials. The possible nucleation mechanisms are frictional energy induced melting and strain-related nucleation. It leads to the future study of nucleation theory.
Key words: wear, nanocrystals, phase transformation, asperity, nucleation.

1. INTRODUCTION

The development in microelectro mechanical systems (MEMS), the atomically ordered nanostructures such as Nano-MOSFETs, and tiny fluid power devices for bio-applications, etc., have challenged manufacturing precision products such as micro-pumps, micro-engines, and micro-robots [1-14]. There are existing methods, such as surface coatings, lithographic techniques, self-assembly, etc., developed to fabricate small devices. Yet, the synthesis of precisely defined artificial molecular architectures beyond 25 nm in length is often unattainable, due to solubility, material throughput, and characterization constraints [15-20].

Generating nanoscaled phases with desired size, shape, and crystal structure is critically important for nanotechnology development. The motivation of this research is to investigate the doping/nucleation mechanisms of low-temperature systems through friction triggered atomic doping and nucleation.

This paper reports our findings from experiments. It has been widely accepted that friction activates the surface reaction sites by bond stretching, bond breaking, and reformation [21-30]. Using an AFM, experimental evidence supports the mechanism involving mechanical stimulation-enhanced mass transport of ions to nucleation sites [31-32]. Due to friction, spontaneous, heterogeneous nucleation produces nanodeposits on brushite surfaces. In this research, effects of friction on interactions of Ga and Si are investigated.

Doping Ga into Si, the surface and phase changes under the friction stimulation are studied. Due to the small nature of asperity contact, small features are expected to form that are potentially useful for nanoscale study. The doping takes place when Ga is rubbing against a Si substrate in ambient conditions. The Ga has a low melting point (29.78 oC) and Si has a high one (1410 oC). This material pair undergoes eutectic phase transformation at temperatures around 29 oC. Due to the low equilibrium concentration of Si, the eutectic phase formed during cooling will remain small in size. The numerical analysis method is used to understand the growth mechanisms of crystalline features.

2. EXPERIMENTAL PROCEDURE

2.1. Materials

Gallium is a soft metal with a low melting temperature (29.78oC). With a boiling point of 2070oC, Ga forms an equilibrium eutectic structure below 30oC with low silicon concentration. A typical example is the gallium (Ga) and silicon (Si) system, as illustrated in Figure1 with a Ga-Si phase diagram[33]. Gallium forms a eutectic with small quantities of 5x108 atom% Si at 29.8 oC and exists as a perfectly mixed liquid over a broad temperature and composition range. The eutectic phase contains only about 10 gallium atoms per million silicon atoms. Nanorods and nanowires have been obtained using a low-temperature vapor-liquid-solid synthesis method [34- 41].

Produkt-Details

• Erscheint lt. Verlag: 11.7.2006
• Zusatzinfo: XVIII, 324 p.
• Verlagsort: Dordrecht
• Sprache: englisch
• Themenwelt: Technik ► Elektrotechnik / Energietechnik
• Schlagworte: Biotechnology • Carbon Nanotubes • Development • Laser • Materials Science • microelectromechanical system (MEMS) • microsystems • Motor • naadje • nanotechnology • Nanotube • Production • Sensor • Simulation
• ISBN-10: 1-4020-3951-4 / 1402039514
• ISBN-13: 978-1-4020-3951-5 / 9781402039515