Preface : This book is intended to be a companion to Kubaschewski’s Metallurgical Thermochemistry, and as such deals primarily with the kinetic and transport theory of high temperature chemical reactions. I have chosen the title Thermochemical Processes rather than High Temperature Materials Chemistry since many of the important industrial processes which are described hardly deserve the high temperature connotation, and such a title would have implied a larger structural and thermodynamic content than is required for the description of
the industrial processing of materials. It will be seen that the book has a significant content from the chemical engineer’s approach, and I feel that this rapprochement with the materials scientist is overdue. The origins of the material contained in this book are to be found in the rapid growth of the scientific description of extractive metallurgical processes which began after World War II. This field was dominated by thermodynamics originally, and the development of kinetic and transport descriptions of these processes followed later. At that time the study of glasses and ceramics was largely confined to phase diagrams of the multicomponent systems, and processes in which gaseous reaction kinetics were rate-controlling were of more interest to the chemist than to the materials scientist, a field which, practically, did not exist in that era.
The quantitative description of materials processing has now advanced to the state where most of the processes which are in industrial use can be described within a logical physico-chemical framework. The pace of development in this field has largely been determined by the rate of improvement of our experimental capabilities in high temperature chemistry; the ab initio theoretical contribution to the building of our present knowledge is growing rapidly under the influence of computer capabilities which simplify the fundamental basis for a priori calculation. However, the processes and substances with which the materials scientist works are usually complex, and the precision of the information which is required to describe a process accurately is still too high to be calculated theoretically. The practical situation can now be assessed from the substantial results of experimental studies which cover almost every situation to be found on the present industrial scene. The role of the physico-chemical study of materials processing has been consigned to a secondary position of interest by those engaged directly in manufacturing processes. This has probably come about for two reasons. The first and most obvious reason is that economic factors more than physical chemistry play the important part in industrial decision-making. Those who direct the production aspects of industry seldom have equally developed skill in the physico-chemical aspects as well as in economics. As a result, the decisionmaking tends to be under financial direction, and the decision-makers draw their scientific advice from research in a digested form. The second reason is that high temperature chemists have been fully occupied up till now in the business of understanding the processes already in use and their contributions to industrial progress seem always to be post hoc. At present, it is true to say that their efforts have been more of value in teaching the student laboratory workers than in predicting potentially new processes. To some extent, this state of affairs has been brought about by empirical industrial progress which has built up a formidable amount of knowledge over decades by the use of works trials. These aspects of industrial development together with the financial constraints of process innovation probably account for the fact that the physical chemist has had no really outstanding impact on the materials industry to date, apart from providing experimental tools for the appraisal of new processes, and the ‘tools of thought’ which can be transferred from the analysis of an established process to prognosis when new methods are being sought. The treatment in this book is intended for those who have already received the basic courses in classical thermodynamics which nearly all students of materials science and chemical engineering must assimilate nowadays before passing on to courses in materials processing. For the interested graduate, a brief refresher in any of the standard textbooks of physical chemistry is recommended if he/she is not comfortable in thermodynamic analysis. References are given at the end of each section to other works and original literature sources which are normally available to the student of materials science. Rather than present the reader with a plethora of original references, I have collected a number of review articles, and monographs which have seemed to me to be valuable oversights in this subject. A parallel study of these reference materials will augment the value of this book very considerably, but it is hoped that the main ideas which are germane to the analysis of processes are to be found here. In conclusion, any author who has had the experience of seeing a subject grow from its early beginnings should acknowledge his debt to the leading men in the field who have taught him how to reach a level of competence and ‘feel’ for the subject. Among the many colleagues who have played this role for me, I would place F.D. Richardson and O. Kubaschewski as the prime movers during the years I spent in the Nuffield Research Group, and others, such as H.J.T. Ellingham, L.S. Darken, and of course, C. Wagner, with whom I ‘sat at the master’s feet’. To all of those who remember having worked with me over the last fifty years, I would extend my thanks for friendship coupled with instruction. Finally I must acknowledge the ever-present support and encouragement which I have received from my wife who has never failed to help me in high times and low with her insight into what forms scientists outside of their working persona.
The quantitative description of materials processing has now advanced to the state where most of the processes which are in industrial use can be described within a logical physico-chemical framework. The pace of development in this field has largely been determined by the rate of improvement of our experimental capabilities in high temperature chemistry; the ab initio theoretical contribution to the building of our present knowledge is growing rapidly under the influence of computer capabilities which simplify the fundamental basis for a priori calculation. However, the processes and substances with which the materials scientist works are usually complex, and the precision of the information which is required to describe a process accurately is still too high to be calculated theoretically. The practical situation can now be assessed from the substantial results of experimental studies which cover almost every situation to be found on the present industrial scene. The role of the physico-chemical study of materials processing has been consigned to a secondary position of interest by those engaged directly in manufacturing processes. This has probably come about for two reasons. The first and most obvious reason is that economic factors more than physical chemistry play the important part in industrial decision-making. Those who direct the production aspects of industry seldom have equally developed skill in the physico-chemical aspects as well as in economics. As a result, the decisionmaking tends to be under financial direction, and the decision-makers draw their scientific advice from research in a digested form. The second reason is that high temperature chemists have been fully occupied up till now in the business of understanding the processes already in use and their contributions to industrial progress seem always to be post hoc. At present, it is true to say that their efforts have been more of value in teaching the student laboratory workers than in predicting potentially new processes. To some extent, this state of affairs has been brought about by empirical industrial progress which has built up a formidable amount of knowledge over decades by the use of works trials. These aspects of industrial development together with the financial constraints of process innovation probably account for the fact that the physical chemist has had no really outstanding impact on the materials industry to date, apart from providing experimental tools for the appraisal of new processes, and the ‘tools of thought’ which can be transferred from the analysis of an established process to prognosis when new methods are being sought. The treatment in this book is intended for those who have already received the basic courses in classical thermodynamics which nearly all students of materials science and chemical engineering must assimilate nowadays before passing on to courses in materials processing. For the interested graduate, a brief refresher in any of the standard textbooks of physical chemistry is recommended if he/she is not comfortable in thermodynamic analysis. References are given at the end of each section to other works and original literature sources which are normally available to the student of materials science. Rather than present the reader with a plethora of original references, I have collected a number of review articles, and monographs which have seemed to me to be valuable oversights in this subject. A parallel study of these reference materials will augment the value of this book very considerably, but it is hoped that the main ideas which are germane to the analysis of processes are to be found here. In conclusion, any author who has had the experience of seeing a subject grow from its early beginnings should acknowledge his debt to the leading men in the field who have taught him how to reach a level of competence and ‘feel’ for the subject. Among the many colleagues who have played this role for me, I would place F.D. Richardson and O. Kubaschewski as the prime movers during the years I spent in the Nuffield Research Group, and others, such as H.J.T. Ellingham, L.S. Darken, and of course, C. Wagner, with whom I ‘sat at the master’s feet’. To all of those who remember having worked with me over the last fifty years, I would extend my thanks for friendship coupled with instruction. Finally I must acknowledge the ever-present support and encouragement which I have received from my wife who has never failed to help me in high times and low with her insight into what forms scientists outside of their working persona.
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