This book deals with the physico-chemical principles underlying ion exchange sorption and chromatog~aphy. It does not cover in any detail the experimental and instrumental aspects of practical separations. The author has developed the subject starting from the synthesis and structure of the ion exchangers employed, through the thermodynamics of sorption selectivity and the equilibrium dynamics of ion sorption, to the kinetics and dynamics of non-equilibrium ion-exchange systems. Throughout this treatment the additional factors arising from the exchange of complex organic ions, as opposed to simple mineral ones, have been interwoven. The author has stressed the application in the separation of organic ions with biological activity, many of which are synthesized in biotechnological processes, and in view of this he uses the expression "physico-chemical biotechnology." In practice, however, his in-depth treatment is applicable to any charged organic species with multifunction ality and/or high molecular weight, and is therefore by no means restricted to biologically active materials, and certainly not to those molecules from a biotechnological source. Bearing this in mind, the text has a much wider value than the title may convey.

The present stage of technological development makes new and ever more complex demands on materials that have to work under conditions of high temperature and pressure, in high vacuum, and in corrosive media. In consequence special importance is now at tached to the refractory compounds of transition metals of groups IV to VI with such nonmetals as boron, carbon, silicon, and nitro gen. These compounds possess high melting points, great hard ness, and high refractory and corrosion-resisting properties. The most widely used and important compounds of this type from a technological point of view are the carbides, which are already fairly widely used in various fields of technology. The present collection of papers contains the results of re cent investigations into methods of producing high-purity carbides and also components made of the carbides and their alloys. Great attention has been paid to the study of a wide range of properties of the carbides and of alloys based on them, viz., the electro-and thermophysical, thermodynamic, mechanical, and chemical prop erties, and also to the utilization of the carbides as wear-and abrasion-resistant materials. In contrast to many previous publications dealing with carbides, the results presented in this collection relate to the properties of carbides having a definite phase composition, corresponding to a higher degree of purity 0 In some of the contributions the physical and chemical properties of the carbides are interpreted in terms of certain solid-state models and concepts concerning the types of chemical bonding in these compounds."

The book we are presenting to American and other English speaking readers is a review of the work on the electron struc ture of elements, alloys, and compounds, which was started back in the fifties. This work gradually grew into a system of ideas on the electron structure of condensed matter which is now known as the configurational model. This model is based on the assumption of the preferential formation of the most stable configurations of the localized va lence electrons in condensed matter. The existence of these stable configurations and the exchange of electrons with the de localized (collective-state) subsystem determines those prop erties which are related to the electron structure. The conclu sions which can be drawn from the applications of the configura tional model are only qualitative but they explain quite clearly the nature of various properties of condensed matter, and they are helpful in the search for materials with specified properties. The American edition has been corrected and supplemented in many minor respects. Moreover, the opportunity was taken to revise thoroughly the section on the fundamentals of the configura tional model in the light of the latest theoretical developments. other parts of the book have been shortened to eliminate material which is not of fundamental significance or has not yet been de veloped sufficiently fully."

This collection sets out the results of various investigations into the chemical properties of refractory compounds and refractory-base alloys used in various fields of modern technology, together with original methods of analysis. The book is intended for analytical chemists, engineers, workers in scientific-research establishments and industrial laboratories, graduates, and students of the senior courses in chemical and metallurgical higher-education institutions. v CONTENTS Interaction of the Carbides of Group IV and V Transition Metals with Various Acids E. E. Kotlyar and T. N. Nazarchuk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Method of Quantitative X-ray Analysis for Determining the Amount of Free Carbon in Boron Carbide M. I. Sokhor and G. V. Sofronov . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Method of Separating and Determining the Free Carbon in Materials Containing Refractory Compounds L. A. Mashkovich and A. F. Kuteinikov . . . . . . . . . . . . . . . . . . . . . . . . . . . " 14 Stability of Boron-Carbon Compounds in Oxygen at High Temperatures L. E. Pechentkovskaya and T. N. Nazarchuk . . . . . . . . . . . . . . . . . . . . 20 Certain Chemical Properties of Boron Carbonitride L. E. Pechentkovskaya and T. N. Nazarchuk . . . . . . . . . . . . . . . . . . . . . . . . . . 25 Oxidation of Boron, Gallium, and Indium Phosphides in Air L. L. Vereikina . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 High-Temperature Oxidation Resistance of Refractory Silicon Nitride-Silicon Carbide Materials I. N. Godovannaya and O. I. Popova . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . " 33 Production and Chemical Stability of the Hydrides of Group IV and V Transition Metals M. M. Antonova . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 Chemical Analysis of the Reaction Products of Boron with Arsenic and Phosphorus A. A. Reshchikova and Z. S. Medvedeva . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 Complexonometric Analysis of Molybdenum Alloys L. N. Kugai, O. F. Galadzhii, and V. I.

The continuous and ever expanding development of high-temperature tech nology involves the use of high -temperature refractory materials and one of the most important classes of these is the oxides, i.e., compounds of elements with oxygen. Oxides are the oldest refractory compounds known in technology and this is connected with their high chemical stability and abundance in nature. In addition to the use of oxides as raw materials for metallurgical processes, the refractoriness, chemical stability, and magnetic and other technically important properties of oxides have been put to use since antiquity. At the present time the importance of oxides as bases of many materials for new technology is substantial and is growing rapidly with the development of processes for the direct conversion of various forms of energy into electrical energy, the development of nuclear technOlogy, electronics, semiconductor and dielectric technOlogy, and cosmic technology, where the refractoriness and chemical stability of oxides are used in combination with their specific physical properties. Oxides are the foundation of the so-called oxygen -containing or oxygen refractory materials, which are fundamental to high-temperature tech nology. Oxides are no less important as the bases of practically all structural ma terials and rocks. A number of oxides are involved in biological processes."

V. I. MATKOVICH During the meeting of the International Symposium on Boron held in October, 1972 in Tbilisi, U.S.S.R., the idea was proposed to assemble a review of boron and refractory borides by the specialists present. The advantages of such a work were immediately apparent. Such diverse applications of borides as in protective armor, nuclear reactors, coat ings, reinforcement, etc. can hardly all be presented in sufficient detail by a single author. On the other hand it was also recognized that with so much specialization, some areas of interest may not be covered. Within the last decade or two a number of areas have been developed in which the use of refractory borides is growing and improvements are being actively explored. Thus, a number of borides have considerable potential as reinforcing material for plastics or light metals, though only boron fibers have been firmly established up to the present. Ap plication of flakes and films for two-dimensional reinforcement appears attractive, although the high cost of materials and development repre sents a considerable barrier. A number of borides have been used to manufacture lightweight protec tive armor. In this area relatively fast changes seem to be taking place as improvements in performance and weight are made. Boron carbide has found considerable use in this application and new developments exploit the light weight of beryllium borides."

One of the most effective methods of increasing the wear resistance, hardness, surface strength and high-temperature oxidation resistance of metals and alloys is the diffusion satu ration of the surfaces by metals and nonmetals. For communicating and discussing the results of the numerous researches carried out in this field in the Department of PJ: tysicotechnical Problems of Materials Science, Academy of Sciences of the UkrSSR, a permanent Scientific Seminar was set up in 1961, which enjoys an ever-increasing popularity among specialists in this field. The present collection contains papers read at the Third Session of this Seminar, held on September 25-28, 1963. The compilers of the collection and the authors of the papers hope that its publication in the U. S. A. will enable American specialists to become acquainted with the main lines along which corresponding work is being conducted in the USSR. This should contribute to an ex change of scientific experience in this interesting field which is of such great practical impor tance. G. V. Samsonov PREFACE This collection is comprised of papers relating to the diffusion saturation of metals and to coatings of refractory compounds. The papers discuss current problems in the theory and practice of the production of diffusion coatings on metallic materials. A means of classifying the methods of diffusion saturation is proposed, and a new method is described for calculating the diffusion parameters in a heterogeneous medium."