October, 1926
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science and the scientist must see that his results are stated in understandable language. I n the teaching of metallurgy we must get away from the merely descriptive and dig into Historians of science have recognized the debt that chemistry fundamentals. As aids to teaching, models and lantern owes t o the practical metal smelter and refiner. Centuries of slides may be all right, but what the metallurgist needs to experience in the extraction of metals from their ores and in the removal of impurities by refining led t o the accumulation of a know is how the blast furnace and open hearth work and vast store of facts, on which the scientific chemist could draw at not what they look like. Attention to the physical chemistry need, and studies of the behavior of metals are prominent in the of steel-making has been too largely diverted to the question Mayow, work of most of the founders of chemistry-Boyle, of heat treatment, with the result that many students get Priestley, and Lavoisier. In more recent times the debt is being their metallurgy backward. They start with the finished repaid; the practical metallurgist making use of the knowledge gained by the scientific chemist t o improve his processes or to product and often end there and have. scant appreciation devise new ones, t o remove harmful impurities or t o modify the of the possibilities or limitations of blast-furnace or steelproperties of metals by the formation of new alloys. Metallurgical science is an application of physics and chemistry t o the melting processes. The subject of heat treatment is a vital one and should not be overlooked, but steel-making chemistry special cases of the metals, and the corresponding art is founded. more or less deliberately as industry advances, on the science.* is not so strongly emphasized as it might be. I n fact, the field for research is very great in filling in the gaps in our Closer Cooperation between Theory and Practice knowledge. so that in the future exact scientific control methods may be applied not only to steel in its final form in must look If progress in the industry is to be made, for closer cooperation between theory and practice. The the user’s hands, but to every step from the ore to the appliman must have an open mind to the findings of cation. Then metallurgy may be defined as “the science (not the ‘art‘) of extracting metals from their ores and fitting2 J . Chem. SOC.(London),133 (1923). them for use.”
zations should forget that their field is but a branch of applied chemistry. As Professor Desch has said:
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Future Progress in Ceramic Chemistry By George W. Morey GEOPHYSICAL LABORATORY, WASHIXTON,D. C
IFTY years ago a prediction of future progress in ceramic chemistry would have been difficult and it probably would have bthen far from the eventuality. ,4 prediction, to be lucky, should be in the nature of an extrapolation; and the better the data used and the shorter the extrapolation, the better the chance of success. Fifty years ago our knowledge of ceramic. chemistry, as opposed t o ceramic technic, was meager. The industry had developed by age-long trial and error until its methods and processes had become standardized a t a surprisingly near approach t o maximum practical efficiency, but the reasons for the practices and technic employed were wholly unknown. There was not the background of chemical theory necessary to understand these processes, and the multitudinous details of chemical facts necessary to the application of this theory were unknown. A t that time there was not the knowledge requisite to a comprehension of how much was not known. Today me can appreciate our ignorance, and proceed systematically to arrive a t a knowledge of the reasons for the present procedure and, after that, to perceive the way to improvement. The accumulated empirical knowledge of generations is a t our disposal; the past fifty years hare provided us with a background of theory, and a beginning of the accumulation of chemical facts; the future is concerned with the further extension of the boundaries of our knowledge, and the application of this knowledge, guided by sound theory, t o the problems of the varied branches of ceramic manufacture. That such application of scientific knowledge and theory to manufacturing problems will prove fruitful there can be little doubt. Other industries, also heritages from antiquity, have been more ready to displace the rule of thumb by the rule of science, and their example should serve to hearten those who still feel that the way of the fathers is good enough for us. It may be, :is has been claimed, that the problems of the ceramist, primarily problems whose causation is found in that most stubborn of elements, silicon, are more elusive than those of, for example, the metallurgist. But
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even were this so, the silicate chemist has a richer body of experience on which to draw than had those men of the past generation, whose efforts made a science out of the art of metallurgy. For examples of the worth of the scientific method, however, it is not necessary to go to other fields of chemical technology. The past decade has seen many noteworthy accomplishments, and from them i t is possible to ascertain the present trend of the science in ceramics, and to predict the probable course in the future. Cement
The ceramic industry, in common with the other industries of the country, has been greatly benefited by the improvements in mechanical appliances characteristic of the period through which we have just passed, and doubtless such improvements will continue to be made. But the progress toward which we look with more personal interest is that resulting from a greater knowledge of the chemistry of the materials with which we are working. d real beginning toward such a knowledge was made by the work of Rankin and Wright in Portland cement, and here is to be seen an example of how all-inclusive a fundamental research should be. The field of Portland cement occupies but a small portion of the ternary diagram Ca0-A1208-Si02, but to understand the manufacture of cement, or the result of incomplete burning or of overburning, the relations shown by the entire diagram are of importance. This should be but the beginning. Similar studies should be made of other systems closely allied, and especially of systems containing the further components commonly met with in manufacture. The effect of such additional components is still but empirically known; exact knowledge can only be obtained by systematic research, of which the work of Rankin and Fright may serve as a model. That all the possibilities of this work are far from being realized is shown by the recent development of the cements high in alumina. This important development is not a revolutionary discovery of a new material, or of the im-
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provement of an old product by the addition of a new component. Rather, it is the utilization of a portion of the CaO-AlzO&iOz diagram which has hitherto been considered of little industrial importance. The fundamental knowledge was already available. May there not be compositions elsewhere in this system which are of value in special fields? And when we know the effect of addition of further constituents, not only in small amounts, comparable with the impurities present in the raw materials but also in larger amounts, may not further improvements result? Furthermore, what will be the effect of addition of constituents as yet unknown in commercial cement? Such a program of research would be a long and arduous undertaking and would probably require a greater faith in the possibilities of knowledge than can be found in those whose financial support would be essential to such an undertaking. But when future generations, possessing that knowledge, look back upon our limitations, our lack of vision will appear inexplicable. Refractories
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Ceramic Society in definitely including glass, as well as other technologic applications of silicate chemistry, under the term “ceramic chemistry” is to be commended. Progress in glass technology from the chemical standpoint has been considerable in the last few years, and the future will doubtless see a still more rapid advance. The application of the scientific method to glass was given a real trial in the now classic researches of Schott and his collaborators, the direct result of which was the production of new and improved optical glass, thermometer glass, and chemical ware. The indirect results were not so evident; but the success of the factory a t Jena has been an object lesson to the glass trade the world over. To be sure, not many have learned the lesson, even in Germany, so conservatiye is industry; but all are more receptive than they would hare been without the example of three decades of successful application of science to ceramics. Notable advances in the application of silicate chemistry to glass technology hare been made in this country-for example, the lead-free bulb glass for automatic machines, selenium ruby glass, and the discovery of Pyrex. The latter is a n example both of the introduction of a new raw material and of an extension of standard compositions. Boric oxide has been used in heat-resisting glasses for several years, but in small amount and as a constituent of glasses which showed no other novelty in composition. I n Pyrex we have a glass consisting almost entirely of silica and boric oxide, a departure from conventional composition which makes it noteworthy, and which has resulted in a glass greatly superior to its predecessors. Other advances may come in a similar manner by develoging new proportions of t h e usual glass ingredients. One of the most important achievements of Schott was the development of the dense barium crown type of gIasses, which made possible the modern high-speed photographic lenses. Recent unpublished work of Morey and Il’lerwin has shown that the optical properties of these glasses can be duplicated, or even surpassed, without the use of barium oxide, and it is not improbable that greatly improved optical systems wodd result from extensive study of glass compositions over a much broader composition range than has hitherto been studied. This field has hardly been touched by research. The work of Schott was excellent for its time but appears inadequate from the present standpoint. Excellent work in England by Peddle and by Turner and his associates a t the University of Sheffield, has done much to explain the present technic of glass-making. Morey and Bowen have furnished a clue as to what glass is and why it can be manufactured and worked. We are now all r m d y to make real advances in glass technology-in developing new combinations of the usual materials and in producing wholly new glasses-and the future will probably see important advances in both these lines.
Refractory materials are the basis and foundation of all ceramic manufacture. Every product which requires “burning” or melting requires a still more refractory container and furnace, and as we improve our refractories we can improve our product and reduce its cost. Research on the improvement of refractory materials has been, and will continue to be, along the lines of improvement in our present compositions, using the same components, and the introduction of heretofore unused components. The improvement in compositions in recent years has been accelerated and given direction by the work of Bowen and Grieg on the aluminasilica system, which showed that not sillimanite but mullite, a less siliceous compound of the same oxides, plays the dominant role in the burning of clay refractories. Manufacturers have been quick to seize upon the exact knowledge afforded by the work of Bowen and Grieg, and from many quarters we hear of super-refractories approaching mullite in composition. When the difficulties inherent in the manufacture of such refractory material have been successfully overcome, we may expect great ecomonies in other branches of ceramics. Improvement in compositions used for special refractories have resulted from the discovery of the electric furnace group of refractories, of which carborundum and alundum are the best known examples. There also is great activity in the introduction of new refractory oxides, and marked improvement in quality will probably result. It is hoped that the introduction of these improved materials will not be hindered by the imposition of too prohibitive a cost. Many of the oxides which might be used-for example, those of thorium, tantalum, and columbium-would probably cost too much for any but special work, although a large market would no doubt lead to the exploitation of sources unused a t present. The immense deposits of crude zirSilicate Chemistry conia afford a promising source of this highly refractory material, and zirconia, either pure or combined with other Progress in all branches of ceramics, that is, in applied refractories, will probably play an important part among silicate chemistry, depends first on progress in silicate chemthe refractory materials of the future. istry itself, There can be no applied science until there is science to apply, and this is true of ceramics. Continued Glass research is needed, research much more extensive than has According to most definitions of ceramics, the field of heretofore been carried on, and research whose primary glass-making does not come m-ithin the province of ceramic object is to advance our knowledge of silicate chemistry. A considerable proportion of the increase in our knowledge chemistry, but such a restriction of the term is unfortunate. Progress in glass, and progress in the other branches of ceram- of ceramic chemistry, and of the resulting advances and ics, is dependent on a greater and more accurate knowledge profits in manufacture, has been obtained as a by-product of silicate chemistry, and to exclude one branch of silicate of the studies of the Geophysical Laboratory, an institution chemistry from a category which includes its fellows is whose primary interest is not ceramics but geology. It neither logical nor expedient. The action of the American has not been developed as a by-product of industry, nor is
