Powder metallurgy literature in the English language includes a large number of books and several thousand articles in various journals. The rate of growth of this literature increases from year to year. It covers well the whole field of powder metallurg- materials, processes and products - with two exceptions: friction and antifriction branches of powder metallurgy. This lack of information has nothing to do with scientific or technical considerations, and definitely has nothing to do with lack of initiative in the development of these materials. The industry concerned with the production of friction and antifriction materials is continually developing new products and techniques and produc tion is steadily growing. However, most companies working on these materials regard their experiences and new advancements as "proprietary" and, for competitive reasons, are not interested in publishing in the technical literature except for very perfunctory and usually highly commercial papers. Very little work on fric tion and antifriction materials is going on in independent labora tories and university laboratories, although fundamental studies in this field offer very interesting aspects.

The increasing use of powder metallurgy techniques to make an almost infinite variety of materials and products places greater emphasis on utilization of sophisticated experimental techniques. Usually research and development efforts initiate the use of newly developed equipment and analytical procedures. Indeed, the contents of this book are strongly linked to research endeavors, in both the academic and industrials worlds. However, this volume can serve a much needed function in industrial applied powder metallurgy. Although many research ers will find the contents of great value, the technical personnel more involved with production, quality control, customer services and product design now have at their dispo sal a means to learn about the potential uses of several very important techniques. With today's "knowledge explosion" the present set of papers greatly facilitates the comprehension and adoption of new procedures. If powder metallurgy is to continue its rapid rate of growth in virtually all segments of industry, then the transition of modern equipment and procedures from tools of research and development laboratories to everyday plant operations and applications must be hastened. The editors hope that this volume aids in this process, as well as assisting students and researchers by providing a ready source of up-to-date useful information.

The 4th International Symposium on the Science and Technology of Sintering was held on 4-6 November 1987 in Tokyo. Among the many technical sessions was one entitled 'Session for Sintering-Case Study'. Over 200 participants heard these invited talks. Although some papers were over 20 years old, it is necessary to understand the authors' way of thinking. Since the end of the Second World War, many excellent papers related to sintering have appeared in many different academic journals. Some of these papers are still of value, and are still being read by today's students. The questions we have to ask are: Why does the scholar think this way? Why did the scholar perform his experiments? What is the mechanism of sintering? What is the liquid phase of sintering? What is the behavior of sintering additives? What is the history and development of sintering theory? This book includes these sort of historical papers and also new original papers on sintering, all of which are very important to our understanding of the subject. Several papers have been added for this English edition, which is thus more comprehensive than its Japanese counterpart. These papers were spread out in many different sources and the benefits of collecting them together in book form is obvious.