Journal of Surface Engineered Materials and Advanced Technology, 2013, 3, 257-261 http://dx.doi.org/10.4236/jsemat.2013.34034 Published Online October 2013 (http://www.scirp.org/journal/jsemat) Dynamic Impact Absorption Behaviour of Glass Coated with Carbon Nanotubes Prashant Jindal 1* , Meenakshi Goyal 2 , Navin Kumar 3 1 University Institute of Engineering & Technology, Panjab University, Chandigarh, India; 2 University Institute of Chemical Engi- neering & Technology, Panjab University, Chandigarh, India; 3 Indian Institute of Technology, Roopnagar, Punjab, India. Email: * jindalp@pu.ac.in Received July 3 rd , 2013; revised August 5 th , 2013; accepted September 1 st , 2013 Copyright © 2013 Prashant Jindal et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. ABSTRACT Boro-silicate glass samples were coated with chemically treated multi-walled carbon nanotubes (MWCNTs) to study the resistance offered by the coatings under the high strain rate impact. Impact testing of these glass samples was per- formed on Split Hopkinson Pressure Bar (SHPB), where strain rates were varied from 500/s to 3300/s. However, the comparisons were limited to samples subjected to a strain rate of 2300/s to 3000/s so that the effect of only variable deposits of coatings on the stress-strain behavior of glass can be studied. Variable deposits (0.1 mg to 0.8 mg) of MWCNTs were coated uniformly on glass samples having a disc shape with a fixed surface area (79 mm 2 ) to observe the effect of the coating on the impact absorption capacity of glass. It was observed that the small thickness of about 25 µm formed due to the fact that 0.2 mg of MWCNTs deposit spread over the surface increased the impact absorption ca- pacity of the glass pieces by nearly 70%. However, beyond this amount when the deposit was increased to 0.4 mg, the coating thickness got doubled to nearly 49 µm and this led to a fall in absorption capacity which remained static till 0.8 mg deposit. However, even this decrease in capacity was able to absorb 30% more impact than offered by pure glass sample. Keywords: Glass Coatings; Impact Behaviour; Strength; Mechanical Properties 1. Introduction Over the years, impacting resistant materials has been ex- tensively studied using composites that comprise of light weight base matrix and strong filler materials. These ma- terials are tested under extreme impact and static loading conditions so that they can be used for various applica- tions like bullet-proof shields, jackets, resistant surfaces, shock and impact absorbers etc. [1,2]. Apart from fabricating stress resistant materials in the form of composites, absorber coatings also become im- portant when it comes to preserving the basic equipment and acting as a protective coat. These coatings can be sacrificed to protect the base material also. It becomes imperative that such coatings are their light weight so that their own weight does not affect the overall utility of the basic equipment. One of the most useful equipments for studying mate- rial behavior under impact loading is Split Hopkinson Pressure Bar (SHPB). Stress-strain behavior of the spe- cimen when subjected to impact or dynamic loading is obtained when the specimen is subjected to a strain rate of 100 to 10,000/s. The SHPB apparatus consists of two long slender bars namely, an input bar and an output bar that sandwich a short specimen between them. Whenever any load is ap- plied on one end, the sandwiched specimen undergoes very high compression loading. A block diagram of a ty- pical SHPB is shown in Figure 1. The details of working of Split Hopkinson bar set up are widely available in literature [3]. It is basically based upon the measurement of wave signal which is generated by the input and output bars due to high strain rate load- ing. The waves are a measure of strains which are cali- brated to find stress and strain in the specimen and in an earlier work. Impact loading using SHPB on carbon na- notube-polycarbonate composites was also studied [4]. To the best of our knowledge, most of the dynamic and quasi-static strength related work has been done on composite structures [4-9]. Static properties like elastic modulus, indentation pressure and fracture toughness of coatings on glass have been studied by Malzbender et al. [10,11]. In these studies, the composition of the coat- * Corresponding author. Copyright © 2013 SciRes. JSEMAT