• S N Ojha

      Articles written in Bulletin of Materials Science

    • Spray forming: Science and technology

      S N Ojha

      More Details Abstract Fulltext PDF

      Spray forming involves sequential gas atomization of a melt into a spray of fine droplets and their deposition on a substrate to build up a high-density preform. The rapid solidification inherent in spray deposition generates refined, equiaxed and low segregation microstructures. A number of promising features of this near-net shape manufacturing process are highlighted and compared, wherever possible, with the conventional casting and PM techniques. Some commercial nozzles used to create spray and mechanisms associated with spray generation are described. The consolidation of the droplets and the development of the microstructure in the deposit are primarily governed by the nature of the spray and the thermal state of droplets on the deposition surface. Several microstructural characteristics of the deposit are presented and their origin in spray deposition is discussed.

    • Effect of processing on microstructure and wear characteristics of an Al-4·5Cu-10Pb alloy

      J P Pathak S N Ojha

      More Details Abstract Fulltext PDF

      An Al-4·5Cu-10Pb alloy was processed by spray forming as well as impeller mixing followed by chill casting methods. The microstructure, mechanical properties and dry sliding wear characteristics of the alloy were evaluated. The spray formed alloy showed an equiaxed grain morphology with a uniform dispersion of lead particles in the matrix phase. In contrast a cellular-dendritic morphology of the primary phase was the characteristic feature of the alloy processed by impeller mixing and chill casting method. The spray formed alloy indicated its superior mechanical properties and low wear rate particularly at higher applied load and sliding velocity. The possible reason for this behaviour is discussed in the light of microstructure of the alloy and the nature of the worn out surfaces of the wear test specimens.

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    • Dr Shanti Swarup Bhatnagar for Science and Technology

      Posted on October 12, 2020

      Prof. Subi Jacob George — Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bengaluru
      Chemical Sciences 2020

      Prof. Surajit Dhara — School of Physics, University of Hyderabad, Hyderabad
      Physical Sciences 2020

    • Editorial Note on Continuous Article Publication

      Posted on July 25, 2019

      Click here for Editorial Note on CAP Mode

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