Silicon carbide is a strong covalent compound. It is difficult to sinter at high temperature because of its low atomic diffusion. In order to promote sintering and reduce sintering temperature, it is usually necessary to add high temperature sintering aids.al - b - c - b4cThe main solid-phase sintering additives are as follows:al2o3 and y2o3,and i re2o3Among themre2o3Usuallyy2o3、er2o3、yb2o3、sc2o3、lu2o3The liquid phase sintering system is mainly composed of oxides of rare earth elements. The application of a large number of sintering additives will result in the decrease of high temperature strength and deterioration of thermal properties of SiC ceramics. Therefore, exploring suitable sintering methods of SiC ceramics is the focus of ceramic academia.
Spray dryerThe future development will develop and improve spray dryer in depth study of drying mechanism and material drying characteristics, and control of optimal operation conditions for different materials. In addition, large scale, high intensity, high economy, and the adaptability and quality of raw materials for improvement are the basic trend of spray dryer.
Our countrySpray dryerThe industry management and technology development system is required by the drying industry. So its development is actually the result of joint efforts by many industries. Nowadays, people's nearly perfect request about drying technology promotes the renewal and development of drying technology from time to time. There are also new technological innovations and changes needed for the future development of drying equipment, so as to better serve people and play its greatest role.
Spray dryerThe development should also pay attention to energy saving and comprehensive application of energy, as well as the automatic control technology of dryers to ensure the completion of the optimal operating conditions. In addition, with the emphasis on environmental protection, improving the environmental protection measures of spray dryer to reduce the leakage of dust and exhaust gas will also be the direction of further research.
In addition, ceramicsSpray granulatorIn conventional process, powder metallurgy is used to mix sintering additives and matrix ceramic powders, which has some defects such as uneven mixing of additives and introduction of impurities in ball milling media. The traditional ball milling mixing method only achieves the random dispersion of sintering additives in SiC powder, but does not reach the average contact sintering additives from the microscopic point of view of a single SiC particle. How to achieve the average distribution of sintering additives at the grain boundary of SiC to be sintered plays an important role in the densification kinetics of ceramics.
Previously, the Laboratory of Nuclear Energy Data Engineering, Ningbo Institute of Data Technology and Engineering, Chinese Academy of Sciences, discussed the new technology of particle surface wrapping in neutron absorbing boride ceramics. This method broke the difficult problem of low efficiency in traditional ceramic ball milling process, successfully prepared two-phase composite powders with sub-micron average dispersion, and synthesized sintering aids to wrap the core-shell structure of boron carbide on average. The effect of low temperature densification sintering is remarkable. The method is about the outer wrapping of fibers and whiskers.MAXPhase ceramic coatings have also achieved success, showing good universality of synthesis process.
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