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Hafnium Diboride HfB2 Powder application

wallpapers News 2021-12-29
Hafnium compounds are increasingly used in high-temperature, electronic and optical fields due to their high melting point, high energy ray absorption capacity, and high dielectric constant. As a prerequisite for most of these applications, high-density bulk fine ceramic materials are required. Therefore, the preparation of hafnium compounds or fine ceramics containing hafnium compounds is one of the research hotspots of new materials in recent years. Similar to the preparation of other fine ceramics, to obtain high-density hafnium compound fine ceramics, must start from powder, sintering, and post-treatment, and the preparation of powder is the key factor.
The head cones and wing leading-edge of the next generation of manned atmospheric vehicles require structural materials capable of operating in neutral or oxidizing environments greater than 2000C.Ultra-high Temperature Ceramics(UHTC>)C. In addition to their potential applications in aerospace, UHT ceramics are also used in engines, a crucible for molten metal, cutting tools, and wear-resistant coatings.HB2 has been used in the past as an ablative material in high-temperature oxidation environments due to its melting point of up to 3380 C. In subsequent studies, SiC was added as an additive to HfB2 ceramics to increase their oxidation resistance. Dense HfB2-SiC composite ceramics were prepared by hot pressing. The oxidation resistance of the composite ceramics is higher than that of HfB2 ceramics without SIC. The main reason is that the products of oxidation are HfO2 and borosilicate glass after high-temperature oxidation due to the presence of silicon carbide. The borosilicate glass forms a dense coating covering the surface of the sample and prevents further oxidation reaction. Like other ceramics, powder properties are also one of the key factors in the preparation of ceramics. There are many ways to prepare HfB2 powder, but it is generally difficult to obtain nanopowder with high sintering activity.NaBH4 and HfCI4 were placed in an autoclave with quartz tubes, heated to 600'C for 12 h with argon gas, and then cooled to room temperature. The reaction products are cleaned several times with distilled water and ethanol to remove impurities. The final product was dried at 60C in a vacuum, and 25 nm HfB2 powder could be prepared. 

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