Preparation of aluminum nitride powder

wallpapers Education 2021-11-19
Preparation of aluminum nitride powder
High-purity, fine-particle alumina powder, and high-purity, ultra-fine carbon black powder are mixed according to a certain ratio, and a certain amount of AlN is added as a seed crystal, and N 2 gas is passed through the carbon tube furnace for synthesis reaction. The chemical analysis of the final product shows that the aluminum nitride content in the powder is not less than 97%, the oxygen content is about 1%, and the total carbon content (including bound carbon and free carbon) is about 1%. The particle size analysis shows that: 50% particle size is 4μm, 80% particle size is 7μm.
At present, black coatings are obtained on aluminum and aluminum alloy substrates at home and abroad. Most of them are obtained by electrochemical means. Such as anodized black. Black nickel, black chrome, etc. The application of these black coatings. It is to eliminate or reduce the influence of light on people's viewing angle. So most of them are used in other parts of optical instruments. And the nameplates of machines, instruments, and equipment, etc.
First, AlO and carbon form gaseous intermediate products such as Al and AlO through a solid-phase reaction; then the intermediate product forms AlN through a gas-phase reaction under the action of N, CO, and C. In this process, the solid-phase reaction mechanism controlled by diffusion and The vapor-phase mechanism controlled by evaporation exists at the same time; when the reaction temperature is different, the two mechanisms show different degrees and effects. The reaction shows the characteristics of a gas-phase reaction at high temperatures and the characteristics of a solid-phase reaction at low temperatures.
Aluminum nitride (AlN) is an engineering material with excellent performance. At present, although there are many methods for the synthesis of AlN powder, the only ones that can be used in industrial production are the direct nitridation method and the carbothermic reduction method of aluminum powder. Other methods, For example, chemical vapor deposition method, cracking method and plasma chemical method can only be used for experimental research due to the very expensive production cost. Even the two methods commonly used in the industry.
Carbothermal reduction-nitridation method low-temperature synthesis of AIN powder with sucrose (C<, 12>H<,22>O<,11>) and aluminum sulfate (Al<,2>(SO<,4>)<,3> ) Is the raw material. The aluminum nitride powder is synthesized by the carbothermal reduction-nitridation method. Experiments have found that AlON is the intermediate phase of the carbothermal reduction-nitridation reaction, and AlN is obtained from the gas phase nitridation of the AlON intermediate phase. The phrase appears at 1300°C, and AlN is completely formed at 1400°C. Using aluminum sulfate and sucrose as raw materials can greatly reduce the reaction temperature and shorten the reaction time.