Favorable properties of Balsa wood make it an interesting alternative in a number of applications including thermal insulation or as a lightweight core material in sandwich composites. Increasing use in construction necessitates a better understanding of its mechanical and failure properties. In the present work, mode I and mode II fracture toughness for different types of balsa wood and a sandwich structure (balsa as core and fiber glass as skin layer) are studied experimentally by using load-displacement diagrams and visually acquired crack growth data. / Graduation date: 2013

by Li, Kowk Cheung = 利用木材製作具有生物形態的碳化矽 / 李國彰. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references. / Abstracts in English and Chinese. / by Li, Kwok Cheung = Li yong mu cai zhi zuo ju you sheng wu xing tai de tan hua xi / Li Guozhang. / Abstract --- p.i / 摘要 --- p.iii / Acknowledgements --- p.v / Table of contents --- p.vi / List of figure captions --- p.x / List of table captions --- p.xiv / Chapter Chapter 1 --- Introduction / Chapter 1.1 --- Biomorphic products and their potential applications --- p.1 / Chapter 1.2 --- Structures and mechanical behaviors of wood --- p.1 / Chapter 1.3 --- Characteristics and applications of SiC --- p.2 / Chapter 1.4 --- Common methods of producing biomorphic SiC from wood --- p.2 / Chapter 1.4.1 --- Chemical vapor deposition --- p.3 / Chapter 1.4.2 --- Melt infiltration --- p.3 / Chapter 1.4.3 --- Sol-gel process --- p.4 / Chapter 1.5 --- Carbothermal reduction process of silica --- p.5 / Chapter 1.6 --- Objectives of present work --- p.5 / Chapter 1.6.1 --- Comments on the previous works --- p.5 / Chapter 1.6.2 --- Current approaches --- p.6 / References --- p.8 / Chapter Chapter 2 --- Experimental procedures / Chapter 2.1 --- Wood biotemplates --- p.10 / Chapter 2.1.1 --- Balsa --- p.10 / Chapter 2.1.2 --- Flame tree --- p.10 / Chapter 2.2 --- Sol Gel process --- p.11 / Chapter 2.2.1 --- Precursor --- p.11 / Chapter 2.2.2 --- Reaction mechanisms --- p.11 / Chapter 2.2.3 --- "Effects of pH, temperature, and environment" --- p.12 / Chapter 2.3 --- Preparation of biomorphic SiC / Chapter 2.3.1 --- HC1 pretreatment --- p.13 / Chapter 2.3.2 --- Infiltration of silica via sol gel process --- p.13 / Chapter 2.3.2.1 --- Balsa --- p.14 / Chapter 2.3.2.2 --- Flame tree --- p.15 / Chapter 2.3.3 --- Sintering --- p.15 / Chapter 2.3.4 --- Removal of carbon --- p.15 / Chapter 2.4 --- Characterization methods --- p.16 / Chapter 2.4.1 --- Scanning electron microscope and energy dispersive x-ray spectroscopy --- p.16 / Chapter 2.4.2 --- X-ray diffractometry --- p.16 / Chapter 2.4.3 --- Differential thermal analysis --- p.16 / Chapter 2.4.4 --- Compressive strength analysis --- p.17 / Chapter 2.5 --- Summary --- p.17 / References --- p.18 / Figures --- p.19 / Chapter Chapter 3 --- Results and discussions / Chapter 3.1 --- Balsa --- p.21 / Chapter 3.1.1 --- HC1 pretreatment --- p.21 / Chapter 3.1.2 --- Infiltration behaviors --- p.21 / Chapter 3.1.2.1 --- By the standard method --- p.21 / Chapter 3.1.2.2 --- Modified sol-gel process --- p.21 / Chapter 3.1.3 --- SiC products --- p.22 / Chapter 3.1.3.1 --- Volumetric shrinkage and weight loss --- p.22 / Chapter 3.1.3.2 --- Compositions --- p.23 / Chapter 3.1.3.3 --- Morphology and structure --- p.24 / Chapter 3.1.4 --- Optimal infiltration conditions --- p.25 / Chapter 3.2 --- Flame tree --- p.25 / Chapter 3.2.1 --- HC1 pretreatment --- p.26 / Chapter 3.2.2 --- Infiltration behaviors --- p.26 / Chapter 3.2.3 --- SiC products --- p.26 / Chapter 3.2.3.1 --- Volumetric shrinkage and weight loss --- p.26 / Chapter 3.2.3.2 --- Composition --- p.27 / Chapter 3.2.3.3 --- Morphology and structure --- p.27 / Chapter 3.3 --- Mechanisms for the formation of SiC cell walls --- p.30 / Chapter 3.4 --- Compressive strength --- p.31 / Chapter 3.5 --- Summary --- p.34 / References --- p.35 / Tables --- p.36 / Figures --- p.38 / Appendix --- p.65 / Chapter Chapter 4 --- Conclusions and future works / Chapter 4.1 --- Summary --- p.67 / Chapter 4.2 --- Suggestions for future work --- p.68 / References --- p.70