Hybrid glass/graphene coatings with enhanced electrical and thermal conductivities
A new hybrid coating based on a glass matrix with a volume of graphene nanoplatelets content below 4 vol% that confers it with a high electrical conductivity (1.4∙102 S.m-1), thermal resistance at temperatures above 1300 ºC and high corrosion resistance in harsh environments.
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The incorporation of grapheme based filters into glass, ceramic or glass-ceramic materials improve their thermal and electrical performance. However the development of this kind of materials as coating is still very limited.
In the present invention, a procedure for obtaining glass (ceramic)/grapheme hybrid bulk materials and coatings has been developed by using flame spraying of spherical shaped granules consisting of an homogenous mixture if the glass precursor oxides (YAS) and grapheme nanoplatelets (GNPs).
Coatings/materials presenting a good dispersion of the grapheme sheets oriented parallel to the lamellas forming the glass matrix is obtained by a one-step process. Grapheme sheets are arranged forming an interconnect network throughout the length and thickness (100-200 μm) of the coating. Thus, a spectacular increment of 15 orders of magnitude is obtained for the electrical conductivity of the coating (up to 1.4∙102 S.m-1) for GNP contents below 4 vol%. This is the first time that such high values are reported for inorganic coatings with similar grapheme concentrations. In addition, these hybrid coatings show an increment of 30% in the thermal conductivity and also a reduction of the elastic modulus which enhances their performance under external loadings.
Innovations & Advantages
This technology allows, in just one step, obtaining coating/materials with grapheme as filler by thermal spraying techniques with the technological advantages of using a technology widely implemented in aerospace industry. The improvements in the properties encourage their promising application in fields like aeronautic, aerospace or even in nuclear industry, and in particular as:
· Thermal shield in aerospace (Thermal Protection Systems, TPS)
· Electromagnetic/Radiofrequency Interferences shielding (EMI/RFI) or lighting strike protection.
· Environmental protection (Deicing)
They can be also used as bond interface in electronic and/or energy systems.
Current and Potential Domains of Application