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  • br Experimental The base material employed in this study

    2018-11-12


    Experimental The self-flagellation material employed in this study is 6 mm thick Aluminum alloy 6061-T6. The chemical composition of the base material is given in Table 1. The nano sized reinforcement particles such as Ti2B is used at different volume percentages (vol. %) such as 2, 4 and 8. The average size of the reinforcement particles is 35 nm and scanning electron microscope (SEM) microstructure of as-received TiB2 nano-particles are shown in Fig. 1. The square groove was made tangent to the pin in the advancing side and which is 1 mm far away from the center line of the tool rotation on the Aluminum alloy 6061-T6 plate. The H13 tool steel having screwed taper pin profile with shoulder diameter of 24 mm, pin diameter of 8 mm and 3.5 mm height was used. The groove opening initially closed by means of the tool which is having shoulder without pin to avoid the escapement of reinforcement particles from groove while processing. Working range of process parameters along the center line used in FSP are presented in Table 2. The FSP is carried out on a Vertical milling machine (Make HMT FM-2, 10 hp, 3000 rpm) (See Figs. 2 and 3). After FSP, microstructural observations were carried out at the cross section of NZ of surface nano composites normal to the FSP direction, mechanically polished and etched with Keller\'s reagent (2 ml HF, 3 ml HCl, 20 ml HNO3 and 175 ml H2O) by employing optical microscope (OM). Microhardness tests were carried out at the cross section of NZ of surface hybrid composites normal to the FSP direction, samples with a load of 15 g and duration of 15 s using a Vickers digital microhardness tester. The tensile specimens were taken from the surface hybrid composites normal to the FSP direction and made as per ASTM: E8/E8M-011 standard by wire cut Electrical discharge machining to the required dimensions. Wear test is carried out on a pin-on-disk tro-bometer as per ASTM: G99-05 standard. The prismatic pins of 8 mm dia are cut from the stir zone, where the axis of the pin perpendicular to the FSprocess direction. The EN31 steel having a hardness of 62 HRC is used as a disc. The dia of the sliding track on the disc surface is 100 mm. The wear test was carrying out under dry-sliding condition with a constant load of 40 N, disc rotational of speed 650 rpm and sliding speed of 3.4 m/s. Wear rate is determined by, Wear rate (mm3/m) is equal to (volume loss/sliding distance).
    Results and discussion
    Conclusions The nano composite surface layer by reinforcing TiB2 particles on 6061-T6 Aluminum Alloy via FSP successfully fabricated. Influence of nano-sized reinforcement particles of TiB2 (average size is 35 nm) on microstructure, mechanical and tribological behaviour of 6061-T6 Al alloy surface nano composite prepared via Friction stir process was studied and the obtained conclusions are:
    Acknowledgements The author(s) would like to express thanks the authorities of NIT-Warangal, DMRL-Hyderabad and RCI–Hyderabad for provided that the facilities to carried-out my research work. One of the authors Dr. A. Devaraju is thankful to the Principal and the management of S R Engineering College, Warangal-Telangana State, for their constant support during this work.
    Introduction Plastic bonded explosives (PBXs) based on l,3,5,7-tetranitro-1,3,5,7-tetrazocane (HMX) or 2,4,6-triamino-1,3,5- trinitrobenzene (TATB) with various polymer matrices have been formulated in the literature [1–16]. Polymer matrices; Viton A; a vinylidene fluoride - hexafluoropropylene copolymer, Kel-F 800; a vinylidene fluoride - chlorotrifluoroethylene copolymer, polytetrafluoroethylene, Estane 5703; a poly(ester urethane) block copolymer etc. are mainly used for PBXs formulation due to their higher loading density, homogeneity, better dimensional integrity and higher thermal stability than TNT based melt cast compositions. The role of polymeric matrices is to minimise their sensitivity, improved mechanical and high thermal properties [17].