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The properties of glass surfaces
232
Book Reviews
THE PROPER~ESOF GLASSSURFACES. By L. Holland, Chapman and Hall, London, 1964, pp. xvi + 546, 80s. net in U.K. only. THERE has long existed the need for a work covering the field of Mr. Holland’s book and for this reason The Properties of Glass Surfaces will be found useful to all those who work with, or are interested in, glass. The subject matter is almost entirely confined to silicate glasses and has been treated as a review rather than as a textbook. In general the results of published work are referred to in some detail, although at times this has a disadvantage in that the discussion does not always “ hang together “. In some places the text appears as isolated accounts of different papers. The book begins with a brief introduction to theories on the composition and structure of glass, sufficient to acquaint the The first chapter non-specialist with the factors involved. (72 pages) is devoted to the nature of optically worked surfaces. This includes grinding and smoothing processes but the major part concerns work carried out on the mechanism of glass polishing. All the important papers are comprehensively covered although there is little information on industrial practice. There will be some who will not agree completely with the final summary of the relative importance of the mechanisms that have at times been postulated. At the end of this chapter there is an appendix on plastic flow and surface marks which could have been given greater prominence by the inclusion of some discussion on the mechanical strength of glass. Although the author quite rightly states that a detailed discussion of this topic is outside the scope of the work, its complete exclusion has precluded treatment (other than a mention) of such aspects as developments in the Griffith crack theory, the surface energy of glass at normal temperatures, toughened glass, etc. Chapter 2 (48 pages) considers optical properties of glass Reflection and transmission of smooth and rough surfaces. surfaces are covered and there is a good account of the refractive index and thickness of films formed as a result of change in glass surface composition. Anti-reflection coatings are included only in so far as they assist in understanding the optical properties of chemically produced layers. A brief discussion on glass fibres would have augmented this section. The chapter is concluded with the optical assessment of surface finish by multiple-beam interferometry. Chapter 3 (71 pages) is on the surface chemistry and corrosion of glass. The topic is dealt with primarily in relation to aspects such as chemical cleaning, optical working and adsorption. Discussion of the large literature on durability assessment methods has therefore been avoided and attention is focussed on the processes involved in chemical attack on the surface. Porous glasses receive some attention here. The fourth chapter (97 pages), dealing with the sorption of gases and vapours by glass, includes not only the discussion of physical and chemical adsorption of gases, especially water, on cleaned glass but also permeation and diffusion, the absorption of gases during manufacture and their subsequent release during vacuum melting, and adsorption and desorption processes in
ionized and active gases. While the next chapter on the cleaning of glass (57 pages) treats a subject which to many readers will be of great importance, it is one written primarily for the vacuum worker. Although the use of detergents is adequately covered, other chemical cleaning methods receive but scant attention and a worker interested in the cleaning of glass apparatus for, say, electrochemical investigations (where traces of chromate ion can be detrimental) will obtain little help. Vapour degreasing, ultrasonic methods and glow discharge cleaning are throughly discussed. There is a short chapter (18 pages) on the wetting of glass surfaces devoted mainly to contact angle but it does not go into great detail with surface energy considerations nor heat of wetting. A chapter on the frictional properties of glass and the effects of boundary lubricants (27 pages) includes the silicone treatment of glass and is followed by a chapter (54 pages) on the adhesion of metals and polymers to glass. There is little information on glass to glass adhesion. The reactions involved and work of adhesion in sealing metals to glass are discussed in general and particular systems are given in more detail. There are useful tables giving the surface tension values of different glasses and the contact angles of various glasses on metal substrates. The end of the chapter deals with the adhesion of synthetic resins to glass and with glass reinforced plastics. The final chapter (81 pages) is entitled ” Electrical Properties of Glass Surfaces and Thin Layers ” and deals with conduction processes, surface conductivity in humid atmospheres and the prevention of surface Ieakage, conduction in reduced surface layers, surface effects arising from irradiation and dielectric properties of glass foils. There are numerous illustrations throughout the book although many of these are of poor quality and the legend is not always easy to read. Twenty nine plates are grouped together in two places. Each chapter is adequately referenced and there is an author and subject index at the end of the book. Notwithstanding this, because of the method of treatment of the subject matter, it may not always be easy to refer to special points without reading through other material. In places, the wording could be more precise (e.g., page 67, “ glasses with low coordination number “. Page 439, “ the double layer was separated “). There are also several slight errors which should have been corrected during the proof reading (e.g., the preface and introduction are listed together in the contents : page 451, interstitially : different abbreviations are sometimes used for the same journal : instances of authors’ names mis-spelt : some differences between tables and texts : some unusual word usage). On page 47 the lattice energies should be expressed as positive quantities in Kcal/mole and not as, for example, -2626 cal/mol. However, these minor criticisms must not be allowed to detract from the usefulness and great value that will be placed on this very worthwhile work. D. C. CORNISH
Book Reviews
THE PROPER~ESOF GLASSSURFACES. By L. Holland, Chapman and Hall, London, 1964, pp. xvi + 546, 80s. net in U.K. only. THERE has long existed the need for a work covering the field of Mr. Holland’s book and for this reason The Properties of Glass Surfaces will be found useful to all those who work with, or are interested in, glass. The subject matter is almost entirely confined to silicate glasses and has been treated as a review rather than as a textbook. In general the results of published work are referred to in some detail, although at times this has a disadvantage in that the discussion does not always “ hang together “. In some places the text appears as isolated accounts of different papers. The book begins with a brief introduction to theories on the composition and structure of glass, sufficient to acquaint the The first chapter non-specialist with the factors involved. (72 pages) is devoted to the nature of optically worked surfaces. This includes grinding and smoothing processes but the major part concerns work carried out on the mechanism of glass polishing. All the important papers are comprehensively covered although there is little information on industrial practice. There will be some who will not agree completely with the final summary of the relative importance of the mechanisms that have at times been postulated. At the end of this chapter there is an appendix on plastic flow and surface marks which could have been given greater prominence by the inclusion of some discussion on the mechanical strength of glass. Although the author quite rightly states that a detailed discussion of this topic is outside the scope of the work, its complete exclusion has precluded treatment (other than a mention) of such aspects as developments in the Griffith crack theory, the surface energy of glass at normal temperatures, toughened glass, etc. Chapter 2 (48 pages) considers optical properties of glass Reflection and transmission of smooth and rough surfaces. surfaces are covered and there is a good account of the refractive index and thickness of films formed as a result of change in glass surface composition. Anti-reflection coatings are included only in so far as they assist in understanding the optical properties of chemically produced layers. A brief discussion on glass fibres would have augmented this section. The chapter is concluded with the optical assessment of surface finish by multiple-beam interferometry. Chapter 3 (71 pages) is on the surface chemistry and corrosion of glass. The topic is dealt with primarily in relation to aspects such as chemical cleaning, optical working and adsorption. Discussion of the large literature on durability assessment methods has therefore been avoided and attention is focussed on the processes involved in chemical attack on the surface. Porous glasses receive some attention here. The fourth chapter (97 pages), dealing with the sorption of gases and vapours by glass, includes not only the discussion of physical and chemical adsorption of gases, especially water, on cleaned glass but also permeation and diffusion, the absorption of gases during manufacture and their subsequent release during vacuum melting, and adsorption and desorption processes in
ionized and active gases. While the next chapter on the cleaning of glass (57 pages) treats a subject which to many readers will be of great importance, it is one written primarily for the vacuum worker. Although the use of detergents is adequately covered, other chemical cleaning methods receive but scant attention and a worker interested in the cleaning of glass apparatus for, say, electrochemical investigations (where traces of chromate ion can be detrimental) will obtain little help. Vapour degreasing, ultrasonic methods and glow discharge cleaning are throughly discussed. There is a short chapter (18 pages) on the wetting of glass surfaces devoted mainly to contact angle but it does not go into great detail with surface energy considerations nor heat of wetting. A chapter on the frictional properties of glass and the effects of boundary lubricants (27 pages) includes the silicone treatment of glass and is followed by a chapter (54 pages) on the adhesion of metals and polymers to glass. There is little information on glass to glass adhesion. The reactions involved and work of adhesion in sealing metals to glass are discussed in general and particular systems are given in more detail. There are useful tables giving the surface tension values of different glasses and the contact angles of various glasses on metal substrates. The end of the chapter deals with the adhesion of synthetic resins to glass and with glass reinforced plastics. The final chapter (81 pages) is entitled ” Electrical Properties of Glass Surfaces and Thin Layers ” and deals with conduction processes, surface conductivity in humid atmospheres and the prevention of surface Ieakage, conduction in reduced surface layers, surface effects arising from irradiation and dielectric properties of glass foils. There are numerous illustrations throughout the book although many of these are of poor quality and the legend is not always easy to read. Twenty nine plates are grouped together in two places. Each chapter is adequately referenced and there is an author and subject index at the end of the book. Notwithstanding this, because of the method of treatment of the subject matter, it may not always be easy to refer to special points without reading through other material. In places, the wording could be more precise (e.g., page 67, “ glasses with low coordination number “. Page 439, “ the double layer was separated “). There are also several slight errors which should have been corrected during the proof reading (e.g., the preface and introduction are listed together in the contents : page 451, interstitially : different abbreviations are sometimes used for the same journal : instances of authors’ names mis-spelt : some differences between tables and texts : some unusual word usage). On page 47 the lattice energies should be expressed as positive quantities in Kcal/mole and not as, for example, -2626 cal/mol. However, these minor criticisms must not be allowed to detract from the usefulness and great value that will be placed on this very worthwhile work. D. C. CORNISH