Structural and thermodynamic properties of nanocrystalline Cr3C2–25(Ni20Cr) composite powders produced by high-energy ball milling
| Autor: | Olandir Vercino Correa, Nelson Batista de Lima, Cecilio Alvares da Cunha, Lalgudi Venkataraman Ramanathan, Isaac Jamil Sayeg |
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| Rok vydání: | 2016 |
| Předmět: |
Exothermic reaction
Materials science 020502 materials Metallurgy Enthalpy 02 engineering and technology 021001 nanoscience & nanotechnology Condensed Matter Physics ENERGIA Nanocrystalline material chemistry.chemical_compound 0205 materials engineering chemistry Tungsten carbide Crystallite Physical and Theoretical Chemistry Severe plastic deformation 0210 nano-technology Ball mill Chromium carbide |
| Zdroj: | Repositório Institucional da USP (Biblioteca Digital da Produção Intelectual) Universidade de São Paulo (USP) instacron:USP |
| Popis: | Nanostructured coatings have been used to protect components exposed to severe service conditions. High energy milling is widely used to produce nanocrystalline feedstock of coating materials such as chromium carbide and tungsten carbide. This paper presents the structural and thermodynamic properties of Cr3C2–25(Ni20Cr) powders that were high energy milled for different times. During the high energy milling of Cr3C2–25(Ni20Cr) powder, severe plastic deformation takes place. A small part of the energy spent in this process is stored in the crystal lattice as deformation energy. The crystallite size and microstrain in nanocrystalline Cr3C2–25(Ni20Cr) powders milled for different times were determined by X-ray diffraction measurements. Differential scanning calorimetric (DSC) studies of the milled powders revealed a broad transformation, characteristic of a large exothermic reaction in the nanostructured powder. The enthalpy variation measured by DSC permitted determination of the deformation energy stored in the Cr3C2–25(Ni20Cr) powders milled for different times. These measurements also enabled calculation of the specific heat variation of the milled powders. |
| Databáze: | OpenAIRE |
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