Browsing by Author "Murthy, K.V.S."

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Effect of Variations in Mn Content on Mechanical and Corrosion Characteristics of Cu-Al-Mn Shape Memory Alloys; УТИЦАЈ ВАРИЈАЦИЈА У САДРЖАЈУ МН НА МЕХАНИЧКЕ И КОРОЗИОНЕ КАРАКТЕРИСТИКЕ Cu-Аl-Мn ЛЕГУРА СА МЕМОРИЈОМ ОБЛИКА
(Belgrade University, 2024) Mamatha, K.M.; Mallik, U.S.; Koti, V.; Murthy, K.V.S.; Koppad, P.G.
In this work, the role of Mn on the shape memory effect and mechanical and corrosion behavior of Cu-Al-Mn shape memory alloys was studied. The composition of Al was fixed to 10 wt% while that of Mn was varied from 2 to 10 wt%. The strain recovery by SME was evaluated using the bend test, while the yield and ultimate tensile strength were obtained using the tension test. The corrosion behavior was studied using three different solutions: freshwater, substitute ocean water, and Hank’s solution. The yield and ultimate tensile strength of Cu-Al-Mn alloys increased with Mn content up to 6%, which was attributed to grain refinement and precipitation hardening, while the fracture analysis showed mixed mode failure for all alloys. The corrosion behavior of Cu-Al-Mn alloys was modified due to the addition of Mn. With the increase in Mn content, the alloys displayed better corrosion resistance and lower corrosion rates. The corroded surface analysis tested in freshwater showed pitting corrosion, while Cu-Al-Mn alloy with low Mn content was tested in substitute ocean water. Hank’s solution showed surface damage with an unstable surface layer. © Faculty of Mechanical Engineering, Belgrade. All rights reserved
Hardness and electrical conductivity of uncoated and silver coated carbon nanotubes reinforced copper nanocomposites
(Springer, 2022) Koti, V.; Mahesh, n.; Murthy, K.V.S.; Koppad, P.G.; Sethuram, D.
In the present study, carbon nanotube reinforced copper nanocomposites were fabricated using the powder metallurgy technique which includes ball milling and hot pressing. The carbon nanotube weight percentage in the nanocomposite was varied from 0.25 to 1.50% in the steps of 0.25%. Further, to improve the interfacial bonding between the carbon nanotubes and copper matrix, the carbon nanotubes were coated with silver using the electroless deposition method. The sintered and hot pressed copper nanocomposites with uncoated and silver-coated carbon nanotubes were subjected to optical and scanning electron microscope studies to understand the dispersion of nanotubes. The density, microhardness and electrical conductivity of developed nanocomposites were studied. The dispersion of nanotubes was found to be uniform throughout the copper matrix resulting in the improvement in microhardness. Especially when compared with sintered samples, the hot-pressed nanocomposites with silver-coated carbon nanotubes showed significant improvement in microhardness however beyond 0.75% content the microhardness for samples was found to drop. The electrical conductivity of nanocomposites was found to decrease with the increase in the MWCNT content which was attributed to the clustering of MWCNTs due to strong van der Waal forces and the increase in the number of interfaces between MWCNTs and copper matrix. © 2022, Indian Academy of Sciences.
Optimization of Wear Properties of B4C Nanoparticle-Reinforced Al7075 Nanocomposites Using Taguchi Approach
(Springer, 2023) Kumar, G.A.; Satheesh, J.; Murthy, K.V.S.; Mallikarjuna, H.M.; Puneeth, N.; Koppad, P.G.
In the present work, Al7075 nanocomposites with varying B4C contents were produced using powder metallurgy technique. The developed nanocomposites were subjected to microstructure, grain size and wear behaviour analysis. Dry sliding wear test of nanocomposites was conducted as per ASTM G99 standard using pin on disc test ring using Taguchi L9 approach with varying B4C nanoparticles (2.5, 5 and 10%), load (10, 20 and 30 N), speed (200, 250 and 300 rpm) and sintering temperature (500, 550 and 600 °C). Scanning electron microscopy (SEM) analysis showed uniform dispersion and good bonding between B4C nanoparticles and Al7075 matrix. Grain size analysis conducted according to ASTM E112-96 showed that irrespective of sintering temperature the average grain diameter of nanocomposites decreased as the B4C nanoparticle content increased. According to response table for S/N ratio, the most influential parameter on wear volume was B4C nanoparticles content. Worn surface analysis showed delamination and abrasion as dominant mechanisms for nanocomposites with lower B4C nanoparticle content and abrasion for nanocomposites with higher B4C nanoparticle content. © 2022, The Institution of Engineers (India).