|
3754 |
|
Thursday, May 22, 2014, Hall H2 1:40 PM Powders, Wires, Suspensions |
|
New composites for electrical high thermal applications
|
|
Irene G. Cano* / Thermal Spray Centre.CPT. Dpt Materials Science and Engineering. Universitat de Barcelona, Spain David R Vidal / Thermal Spray Centre. CPT. Dpt. Materials Science and Engineering . Universitat de Barcelona , Spain Javier Fernández/ Thermal Spray Centre. CPT. Dpt. Materials Science and Engineering . Universitat de Barcelona , Spa in Jose Maria Guilemany/ Thermal Spray Centre. CPT. Dpt. Materials Science and Engineering . Universitat de Barcelona , Spain |
|
Mullite is an aluminosilicate widely used as a structural material for applications like thermal and environmental barriers coatings. Some of its properties are its low thermal expansion coefficient, low thermal diffusivity and high mechanical properties. For some of these applications, thermal spray is a suitable technique due to its fast production time and versatility. This makes mullite a very interesting coating material for thermal spray industry. In the other side, some of the most nowadays promising research are based on the use of carbon nanofibers (CNFs) as reinforcement in ceramic matrix because they have the potential to change the matrixs behaviour, improving mechanical properties and conductivity and decrease the thermal expansion coefficient and friction. Properly methods to easy incorporate CNFs into ceramic matrix are aim for the promising properties of composites and plasma sprayed coatings. CNFs introduction decreases problems related with coating cracking and is an easy method to improve electrical properties from non-conductive materials as mullite. In Thermal Spray Centre a new method to generate thin coatings in carbon nanofibers by radiofrequency has been designed. This coated carbon nanofibers has been introduced in a mullite matrix and properly coatings has been generated by Air Plasma Spraying. X-Ray Diffraction (XRD) and Raman Spectroscopy of agglomerated powder and plasma sprayed coatings reveal ordered structures, carbon nanofibers presence and degree of graphitization. Scanning Electron Microscopy (SEM) has been used to determine powder shape, coating thickness and adherence. Adherence has been quantified by tensile assays. Conductivity at high temperature has been measured by the voltage drop when a differential potential has been applied to the coating. |