Silica Aerogels: Improvement of Reaction Time and Application as a Host Matrix to Deliver Chemicals
✍ Scribed by I. Smirnova; W. Arlt
- Publisher
- John Wiley and Sons
- Year
- 2001
- Tongue
- German
- Weight
- 44 KB
- Volume
- 73
- Category
- Article
- ISSN
- 0009-286X
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✦ Synopsis
New coating materials for cutting tools are required to improve the economy and environmental compatibility of machining processes. Chemical vapor deposition (CVD) is one technique to apply refractory coatings such as hafnium carbide (HfC), which offers a lot of advantages e. g. high hardness and thermal conductivity. The HfC-CVD process is investigated using a hot wall reactor system operated under reduced pressure to coat TiN precoated cutting tools. Hydrogen, methane and hafnium tetrachloride (HfCl 4 ) are used as a precursor mixture. HfCl 4 is formed by in situ chlorination of hafnium powder with hydrogen chloride in a separate reactor. The CVD process under reaction kinetic aspects and the film properties at different process conditions are focussed in this work. The dependency of the deposition rate from different process parameters are investigated and discussed. The HfC films are characterized by SEM, XRD, AES and TEM.