Researchers from the USA have developed a method of sintering, enabling to create ceramic materials in less than a minute. It does not require expensive equipment and is superior to other methods for rapid sintering maximum temperature and independent of the material properties. The new method solves one of the most important problems of modern development of ceramic materials — increase the rate of synthesis of new compounds, write the scientists in the journal Science.
Traditionally, ceramic materials obtained by sintering of powders at high temperatures (sometimes above 2000 degrees Celsius). Due to its chemical stability, high temperature and mechanical properties, and relatively simple and advantageous methods of producing, ceramics are widely used in many fields such as construction, electronics and energy. Based on ceramic materials are being developed for creating solid oxide fuel cells, and transparent ceramics are used to create optical devices, lenses and scintillators.
Existing methods for creating ceramic materials, however, have several disadvantages. For example, in the traditional method, the sintering process can take up to several hours. This not only increases the time spent on synthesis, but also leads to a change in the composition of the starting compounds, if they contain substances, which are volatile under the action of prolonged heat treatment. A method of microwave sintering depends on the absorbing properties of the material in the microwave range, and the method is spark plasma sintering requires additional compression, which leads to difficulties when creating ceramic structures of complex three-dimensional shapes.
More modern methods — rapid thermal annealing, ultra-fast and photonic sintering is a very high heating rate (up to 10,000 degrees per minute), but they are not without other disadvantages. So, the method is ultrafast sintering depends on the electrical characteristics of the sample, which are often not known, when it comes to the creation of new materials and methods for photonic sintering and thermal annealing have limitations on the heating temperature. In addition they require the use of expensive equipment.
The American scientists under the guidance of Professor Lambin Hu (Liangbing Hu) from the University of Maryland have developed a method of ultrafast high-temperature sintering. It is organized in the following way: the pressed workpiece (powder salts or oxides) is placed between the two carbon strips, which are then heated by electric current. Released during this heat increases the temperature of the workpiece at a speed of 10 to4 degrees per minute. Such a rapid heating to prevent evaporation of the starting materials and mutual diffusion with the material of the heating interfaces. In an inert atmosphere such system can reach temperatures up to 3,000 degrees Celsius. This is enough to create virtually any ceramic materials.