Materials Science Forum Vol. 710

Abstract: Silver reinforced with carbon nanotubes, instead of graphite, would increase both the electrical conductivity, hardness and wear resistance of the electrical brush materials. The effective utilization of carbon nanotubes in the Ag/CNT composite depends strongly on its uniform distribution and strong interfacial adhesion to the silver matrix and thus demands for its surface modification. In order to carry out the surface modification of carbon nanotubes, electroless coating was given to them after liquid phase oxidation, sensitization and activation process. The room-temperature chemical treatment results in a nominally complete coating over the entire outer surface of multiwall carbon nanotube. The surface morphology of the carbon nanotubes after each step has been studied using TGA, DSC, XRD, FTIR and SEM.

Abstract: Multiwalled carbon nanotubes (MWCNTs) were added to Aluminium alloy AA6063 by powder metallurgy route. The samples were compacted, sintered and microhardness was measured on sintered samples. The weight fraction of MWCNTs was varied between 0.5-2.5%. The hardness of the composite has been observed to increase. The ageing curves after solutionizing and artificial ageing have been plotted for various weight fractions of MWCNTs in AA6063 alloy. Electroless copper coating was given to CNTs and the hardness of the samples with Cu coated CNTs in AA6063 showed a higher hardness than the samples without Cu coating on CNTs. Further the ageing curves showed a faster kinetics with increase of MWCNTs in Al6063. This result applied to coated CNTs in 6063 which also showed accelerated ageing kinetics during artificial ageing gives inherent evidence for the Arsenault’s thermal mismatch model of strengthening of MWCNT/Al nanocomposite.

Abstract: A low cost, easily processable, multi layered functionally graded ceramic coating of thickness ~1000 µm was developed to protect metallic substrates from the risk of thermal oxidation. It consists of a four layered functionally graded coating consisting of aluminide layer followed by an intermediate zirconia as thermal insulative layer, an alumina layer serving as buffer layer with the outer most high emissivity layer to provide the required emissivity. All the layers were brush coated and the specimens were cured at 150°C. The solar absorptivity and emissivity of the coating was found to be 0.82 and 0.88 respectively. 15CDV6 plate of 150 x 150 x 5 mm was coated with multilayer thermal barrier coating of thickness ~ 1 mm. The coated sample was subjected to a heat flux of 8.5 W/cm² for 1035 secs to evaluate the thermo-responsive behaviour of the coating. Maximum back wall temperature measured was 299°C. The coating methodology is simple compared to complicated plasma techniques which can be applied on complex shaped substrates and all operations are carried out at low temperatures, below 150°C ensuring no deterioration of structural properties of the substrate.

Abstract: There is an ever increasing demand and innovation worldwide in the area of materials research in aerospace industry. Research on materials is the focused area in aerospace sector because reducing aircraft/spacecraft weight and/or increasing the temperature capabilities is the key factor in increasing the performance. Hence there is always an urge on the development of advanced materials especially in the area of light weight, High temperature resistant materials. There are different ways of keeping abreast on current state of art on the development of advanced materials namely reading Journal publications, attending conferences/seminars or performing intellectual property (IP) analysis specifically looking at patents. Patent portfolio indicates the technology and research direction of a company. Intellectual property plays a key role in the present global competitive world. It is not only an asset for the company but also helps in increasing the bottom line of an organization. Hence, an attempt was made to look at the global patent scenario of materials used for aerospace industry. A high level scan of aerospace materials patent portfolio in the past 20 years was done to understand the current technology focus and trend of materials research. The study was restricted to Aerospace/Aviation Players. Four different types of Materials are considered for the study namely Light weight metals (includes Al and Ti alloys), Superalloys, High temperature coatings and Composites. A further deep dive analysis on the above materials has been done to understand the Industry focus on various technology areas such as Manufacturing, Inspection, Application etc. This analysis helps technologists in understanding the current state of art and research focus in Materials area specific to Aerospace/Aviation Industry