Molybdenum disilicide
Crystal structure | ||||||||||||||||
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Space group |
I 4 / mmm (No. 139) |
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General | ||||||||||||||||
Surname | Molybdenum disilicide | |||||||||||||||
other names |
Molybdenum silicides |
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Ratio formula | MoSi 2 | |||||||||||||||
Brief description |
gray powder |
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properties | ||||||||||||||||
Molar mass | 152.12 g mol −1 | |||||||||||||||
Physical state |
firmly |
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density |
6.31 g cm −3 (25 ° C) |
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Melting point |
1870-2030 ° C |
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safety instructions | ||||||||||||||||
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As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions . |
Molybdenum disilicide is an intermetallic chemical compound of molybdenum from the group of silicides . In addition to this, other molybdenum silicides are known with Mo 3 Si and Mo 5 Si 3 .
Extraction and presentation
Molybdenum disilicide can be obtained by reacting molybdenum with silicon at temperatures greater than 1400 ° C.
Corresponding layers can be obtained by reacting molybdenum with silicon tetrachloride and hydrogen .
properties
Molybdenum disilicide is a gray powder. The connection has a tetragonal crystal structure with the space group I 4 / mmm (space group no. 139) . Above 1900 ° C this changes into a hexagonal structure. In air or pure oxygen, it oxidizes at temperatures above 400 ° C, which can be delayed by using an appropriate alloy.
Molybdenum disilicide is resistant to acids, dilute alkalis, salt solutions and various molten salts. It also stands out from other metals and alloys in that it is corrosion-resistant to reducing and oxidizing gases at temperatures from 1350 to 700 ° C.
use
Molybdenum disilicide is used as an electrically conductive ceramic material, for example in high-temperature heating conductors. In combination with other non-oxide ceramics, it is used, for example, in glow plugs for the automotive industry.
Individual evidence
- ↑ a b c d e f g data sheet Molybdenum disilicide, α-phase, powder, ≥99.8% trace metals basis from Sigma-Aldrich , accessed on May 24, 2015 ( PDF ).
- ↑ a b Sam Zhang, Dongliang Zhao: Aerospace Materials Handbook . CRC Press, 2012, ISBN 978-1-4398-7330-4 , pp. 253 ( limited preview in Google Book search).
- ↑ a b Wolfgang Kollenberg: Technical ceramic basics, materials, process engineering . Vulkan-Verlag, 2004, ISBN 978-3-8027-2927-0 , pp. 135,340,344 ( limited preview in Google Book search).
- ↑ ER Braithwaite, J. Haber: Molybdenum An Outline of its Chemistry and Uses . Elsevier, 2013, ISBN 978-1-4832-9089-8 , pp. 83 ( limited preview in Google Book search).
- ^ Helmut Mehrer, Hans Eckhardt Schaefer, Irina V. Belova, Graeme E. Murch: Molybdenum Disilicide - Diffusion, Defects, Diffusion Correlation, and Creep. In: Defect and Diffusion Forum. 322, 2012, p. 107, doi: 10.4028 / www.scientific.net / DDF.322.107 .
- ↑ O. Rubisch: Molybdenum disilicide, a high temperature material for extreme chemical and thermal loads. In: Materials and Corrosion / Werkstoffe und Korrosion. 16, 1965, p. 467, doi: 10.1002 / maco.19650160604 .
- ↑ HC Starck: Product Information Molybdenum Disilicide ( Memento of the original dated May 24, 2015 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. , accessed on May 24, 2015.