Faculty Publications

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Effect of arctic environment on flexural behavior of fly ash cenosphere reinforced epoxy syntactic foams
(Elsevier Ltd, 2018) Garcia, C.D.; Shahapurkar, K.; Doddamani, M.; Mohan Kumar, G.C.M.; Prabhakar, P.
In this paper, the effect of arctic conditions on the flexural response of cenosphere/epoxy syntactic foams is investigated. Understanding the behavior of such foams under extreme conditions is critical for exploring their suitability for constructing lightweight platforms used in arctic explorations. Such platforms are exposed to subzero temperatures for extended periods of time potentially degrading their mechanical properties. In the research study presented here, samples of cenosphere/epoxy syntactic foams were conditioned under arctic environment at ?60 °C temperature for a period of 57 days. Flexural tests were then conducted at room temperature as well as in-situ ?60 °C on the conditioned samples and compared against unconditioned samples. Combinations of surface modification and cenosphere volume fractions were considered. Experimental findings showed that an increase in flexural modulus can be observed at room temperature with increasing cenosphere volume content for both untreated and treated cenosphere reinforced syntactic foams. In contrast, a decrease in flexural strength was observed as compared to neat resin. For the case of arctic exposed samples, an apparent increase in flexural modulus was recorded between 7-15% as compared to room temperature cenospheres/epoxy syntactic foams. In addition, an apparent increase of 3–80% in the flexural strength was observed under arctic environment. The conditioning of cenosphere/epoxy syntactic foams under low temperatures manifested lower strains to failure as compared to neat epoxy and they exhibit quasi-brittle behavior leading to sudden failure in the post peak regime. © 2018 Elsevier Ltd
Influence of surface modification on wear behavior of fly ash cenosphere/epoxy syntactic foam
(Elsevier Ltd, 2018) Shahapurkar, K.; Chavan, V.B.; Doddamani, M.; Mohan Kumar, G.C.M.
The present study deals with investigating the surface modification effect of fly ash cenosphere (as received and surface treated) on the friction and wear response of epoxy syntactic foams. Such lightweight syntactic foams have the potential in using them as tribo-materials for friction applications like in brake pad composites. This study also addresses the environmental linked disposal issues of fly ash cenospheres by incorporating them (up to 60 vol%) in the epoxy matrix. Cenosphere content and surface modification influence on the friction and wear response of cenosphere/epoxy syntactic foams is investigated against EN31 steel disc under dry sliding conditions. Wear behavior is studied at room temperature for different velocities (2 and 5 m/s), applied loads (30 and 50 N) and sliding distances (3, 5 and 7 km). Neat epoxy exhibits maximum wear rate as compared to foams. Wear rate decreases with increasing sliding distance and cenosphere content at all tested conditions. With the increase in the applied load and the sliding velocity, higher wear rate is noted for neat epoxy samples while it decreases with increasing filler loading. Surface modified cenosphere reinforced foams exhibit better wear resistance compared to as received cenosphere dispersed foams and neat epoxy for all the operating conditions owing to the good interfacial bonding of treated cenospheres with epoxy matrix. Specific wear rate decreases significantly with an increase in applied load. Further, the coefficient of friction decreases with higher filler loading and surface modifications. Scanning electron microscopy is used to study the wear mechanisms. Wear debris is analyzed and disc temperature is also reported. Finally, wear rate results are summarised and compared with the data available from literature and are presented in a property map. © 2018 Elsevier B.V.
Effect of cenosphere filler surface treatment on the erosion behavior of epoxy matrix syntactic foams
(John Wiley and Sons Inc. cs-journals@wiley.com, 2019) Shahapurkar, K.; Doddamani, M.; Mohan Kumar, G.C.; Gupta, N.
Influence of cenosphere surface modification and volume fraction on the solid particle erosion of cenosphere/epoxy syntactic foams is investigated. Fly ash cenospheres are used as filler in both as received and silane surface modified configurations. Erosion behavior is studied at room temperature for different impact angles (30, 45, 60, and 90°) and velocities (30, 45, and 60 m/s). Neat epoxy shows the highest erosion rate compared with that of the syntactic foams. Results show a strong dependence of impact angle and velocity on erosion rate of syntactic foams. With increasing cenosphere content erosion rate decreases for all impact angles. Erosion rate decreases with increasing impact angle and with decreasing velocity. Good interfacial bonding of treated cenospheres enhances the erosion resistance. All the samples exhibit ductile erosive behavior, with maximum erosion at 30°. The velocity exponent and erosion efficiency parameters confirm the ductile behavior of syntactic foams. POLYM. COMPOS., 40:2109–2118, 2019. © 2018 Society of Plastics Engineers. © 2018 Society of Plastics Engineers

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