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Nowadays glass and ceramics, or earthenware, have become a truly indispensable part of our household, and practically all and any productive activities. It would be no exaggeration to say that both these materials have a key role to play in our progress in general. Corresponding members of the Russian Academy of Sciences-Vladimir Shevchenko (Director of the Grebenshchikov Institute of Chemistry of Silicates) and Gennady Tereshchenko (First Deputy Minister of Science and Technology of the Russian Federation) take a closer look at the history of these materials, the present state of the art and their development prospects.
By and large, the term ceramics covers all sorts of materials based on inorganic non- metallic compounds produced by means of sintering or burning. And the term glass is usually applied to materials which are in an amorphous and metastable condition or state.
As proved by archeological excavations, as far back as 10,000 years B.C. people were already using utensils made of fired clay, and the material on a different basis-faience earthenware or glazed pottery-was first produced in Egypt and in the Middle East ca. 4000 B.C. This was a mix of ground quartz or sand (often with an addition of lime) with alkali metal oxides and pigments on the basis of copper compounds.
A new stage in the development of ceramic materials was opened up by the advent of metallurgy in the early third millennium B.C. when ceramics came to be used for the linings of smelting furnaces, forms and crucibles. In ancient Rome and in Europe of the Middle Ages refractory materials had about the same composition as some of those which are now in use. At the start of the 1st century A.D. Roman engineers developed a technology of cement
production which gave a boost to housing construction and urban growth.
As for glass, the art of its manufacture was known to craftsmen as far back as the Bronze Age; but the full-scale production of glassware of all shapes and sizes was launched in the Roman Empire at the turn of the 2nd century A.D.
The present-day menu of ceramic products includes things like high-quality refractory materials, spark plugs for cars, luminescent displays, ferroelectrics, (*) electronic radio components and superconductors, to name but a few. These things are indispensable to space rockets, aircraft and many other branches of civil and military engineering.
In the 1970s a whole range of applications was suggested for the newly developed materials called sitalls (**) (glass ceramics) and inorganic fibers. They provided the basis for the manufacture of high-strength quartz basalt and glass fibers and also for different fabrics for technical applications. At the same time technologies were mastered for the production of bio-compatible materials and some very pure substances of a preset composition, which made it possible to launch the production of what are called bio- compatible osteo and dental prostheses for medical applications.
Important achievements in this field were also scored in the 1980s. At that time considerable progress was made in the practical applications of theoretical forecasts and in the methods of investigation of the structure of optical and technical glasses and articles made thereof. This gave new momentum to the development of laser technology, fiber optics communication, non-linear optics and so on. Advances in the dissociative theory of destruction of brittle bodies (ceramics) promoted the development of armour and impact- proof structures. Of great importance were studies of surface phenomena in vitreous and ceramic materials. They paved the way for the production of what are called multi- functional coatings: refractory, corrosion- and chemical-proof ones and also enamels.
In the 1990s the chemistry and physical chemistry of colloidal oxide systems provided the scientific foundation for the manufacture of nanodispersed materials. On the basis of the theory of chemical and radiation stability of amorphous media it was possible to develop technologies and materials for the disposal of chemical, radioactive and biological wastes from modern industries.
The authors of this review focused particular attention on the current state of affairs in this field in Russia. By the 1990s what was then the Soviet Union possessed a powerful industry for the production of ceramic materials. The share of the production of raws and ceramic and glass articles was close to 5 percent of the country's gross output, which matched the statistics of industrially advanced countries (5 percent in the United States, 7 percent in Japan and 6.5 percent in \\est Germany).
The achievements of Russian scientists and engineers in this area were quite impressive and many of them were of pioneering nature. The list included ferroelectrics, the development of new types of ceramic materials for fuel rods at atomic power stations, synthesis of ultra-dispersed diamond powders and production of articles from them, tool materials based on titanium carbonitrides and many other things.
But, as the authors of this review point out, the late 1990s saw a marked decline in the production of ceramics, as well as in other areas, caused by a range of organizational and economic problems faced by this country then. Of major importance in keeping promising R&D projects afloat were programs launched by the Ministry of Science and Technology of the Russian Federation. In future the development of ceramics, vitreous and super- strong materials should be oriented toward energy saving per unit of traditional items (refractories, porcelain, faience or earthenware, glass panels, etc.) and toward the development of new and promising materials for engineering, transport and medical applications. The first fruits of this general strategy are already at hand. For example, specialists have developed shock-proof ceramics for solid-state electronics and communications, and also for medical and biological applications.
Industrial technologies have been mastered for the production of a wide range of vitromaterials and coatings for laser and aerospace applications, and composite materials have been obtained with ceramic and metallic matrixes. At the Lebedyansk Dressing Plant, for example, specialists have launched the production of sigran-a new vitrocrystalline material developed by scientists of the Russian Chemico-Technological University (named after Mendeleyev). Researchers of the Institute of Physico-Chemical Problems of Ceramic Materials (Russian Academy of Sciences) have developed new materials on the basis of silicon carbide as well as silicon and boron nitrides. The SHLAKOLIT Engineering Center and the Izhorsky Plant (St. Petersburg) have launched the production of ceramic coatings, tubings and collectors for subways, and inserts for rail junctions. The Research Institute of Glass together with the MIG Moscow Aircraft R&D Center has pioneered a technology of vitrification of commercial aircraft (GZHEL type technology).
The TERM R&D Center has launched the production of what they call high-modular fibers and fabrics of different structure for agencies like GAZPROM (in charge of the gas industry) and MINATOM (nuclear
* Ferroelectrics-crystalline substances having spontaneous electric polarization (in the absence of an electric field) within a certain range of temperatures; such polarization is heavily dependent on external conditions.-Ed.
** Sitalls (glass ceramics)-vitreocrystalline materials of one or several crystal phases evenly distributed in the vitreous phase.-Ed.
engineering) of the Russian Federation. In fact, exports of these materials and technologies alone have brought in 28 million rubles (or 1,000,000 US dollars) in profit, while the total economic gain exceeds 225 million rubles (8,000,000 dollars).
Also worthy of mention are several other achievements of Russian researchers in this field. Experts of the Institute of Silicate Chemistry (named after Grebenshchikov) of the Russian Academy of Sciences have developed and patented a technology of synthesis of what they call reactive-bound coatings which makes it possible to cut down by two-thirds resources expended per unit of output. Experts at the SEVERONIKEL R&D Center have developed a method of precipitation of nickel and cobalt in the form of beadings on titanium electrodes, which helps boost the output by 1.5 times. At the Salavatsky Glass Factory in Tatarstan specialists have launched a production line for stained glass panels with the output of up to 5,000 m(2) a year. The resulting savings of raws and other materials exceed 20 mln rubles.
Thanks to the financial and organizational backing provided by the Ministry of Science and Technology of the Russian Federation we have been able to preserve and maintain our internationally recognized schools of research, including those headed by Academicians M. Schultz (glass materials), P. Sarkisov (vitreocrystalline materials), G. Petrovsky (optical materials) and by Corresponding Member of RAS, V. Shevchenko (ceramics).
While studying materials like polymers, glass and ceramics as well as certain metals and alloys, scientists saw there are but two basic characteristics which determine the applicability of these materials in various branches of production. These are their strength and per-unit cost of output. For all of the above materials these basic values lie within a very narrow range, which helps determine the ultimate choice. This fact was first noted by Academician N. Plate in 1997. It thus became possible to map out the basic strategy of research for the future.
In the opinion of the authors of this review, the most rewarding line for the next few decades should be research into ways of broadening the boundaries of operational properties of materials for their use under extreme conditions. Much attention should be given to studies of what is called the ultra-dispersed state of such materials. This should pave the way for new biological materials and above all implants, biosensors and materials providing for the transport of medicines to affected organs (porous media) and for the transport of chemicals to plants.
A special place in today's technological novelties belongs to what are called "intellectual" materials capable of "accepting" external "inputs" or influences and alter their characteristics accordingly. Some of them can model biological systems and are even capable of "learning"-adjusting their response in accordance with the external impact. The above materials include, above all, what we call functional glassware and ceramics which are characterized by non-linear dependencies of their electrical, mechanical and thermal properties.
In the area of production technologies of new materials priority will be given to processes providing maximum economic effect, including "small-tonnage" chemistry and technologies of micro- and nano-powders and materials of a higher class (biocomposites and "functional" glass products).
In the opinion of Academicians Shevchenko and Tereshchenko all that will make it possible for the Russian industry to regain its former positions.
V. Shevchenko, T. Tereshchenko, "Studies, Developments and Innovations in the Field of Ceramics and Glass Materials", Vestnik RAN, Vol. 70, No. 1, 2000.
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