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Department: Atılım UniversitySubject: Hardness

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    Article
    Citation - WoS: 2
    Performance of Boron Nitride Coated Tools and Dies
    (Univ Maribor, Fac Mechanical Engineering, 2013) Kaftanoglu, B.; Dokmetas, N.
    Boron nitride (BN) has been utilized as a significant coating material for cutting tool applications due to its excellent mechanical and chemical properties. Cutting tools, molds and machine parts are coated with BN with the coating system using a sputtering technology - a physical vapour deposition (PVD) process. Design and manufacture of the equipment is made locally. Physical, mechanical and tribological properties such as thickness, friction coefficient, wear, and adhesion are measured by using calotest, tribometer, profilometer, micro and macro scratch test, and nanohardness devices. The results of characterization of the coatings show that wear resistance and hardness increase and BN coatings provide increased efficiency by creating a value-added manufacturing. In this case, the use of BN-coated tools in machining is expected to be one of the best solutions. (C) 2013 PEI, University of Maribor. All rights reserved.
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    Citation - WoS: 3
    Citation - Scopus: 3
    Correlations Between Hardness, Electrostatic Interactions, and Thermodynamic Parameters in the Decomposition Reactions of 3-Buten 3-Methoxy and Ethoxyethene
    (Springer/plenum Publishers, 2015) Hasanzadeh, Neda; Nori-Shargh, Davood; Kayi, Hakan; Javid, Nargess Rezaei
    Decomposition of the three isomeric compounds, 3-buten-1-ol (1), 3-methoxy-1-propene (2), and ethoxyethene (3), at two different (300 and 550 K) temperatures has been investigated by means of ab initio molecular orbital theory (MP2/6-311+G**//B3LYP/6-311+G**), hybrid-density functional theory (B3LYP/6-311+G**), the complete basis set, nuclear magnetic resonance analysis, and the electrostatic model associated with the dipole-dipole interactions. All three levels of theory showed that the calculated Gibbs free energy differences between the transition and ground state structures (Delta G (not equal)) increase from compound 1 to compound 3. The variations of the calculated Delta G (not equal) values can not be justified by the decrease of the calculated global hardness (eta) differences between the ground and transition states structures (i.e., Delta[eta(GS)-eta(TS)]). Based on the synchronicity indices, the transition state structures of compounds 1-3 involve synchronous aromatic transition structures, but there is no significant difference between their calculated synchronicity indices. The optimized geometries for the transition state structures of the decomposition reactions of compounds 1-3 consist in chair-like six-membered rings. The variation of the calculated activation entropy (Delta S (not equal)) values can not be justified by the decrease of Delta[eta(GS)-eta(TS)] parameter from compound 1 to compound 3. On the other hand, dipole moment differences between the ground and transition state structures [Delta(A mu (TS)-A mu (GS))] decrease from compound 1 to compound 3. Therefore, the electrostatic model associated with the dipole-dipole interactions justifies the increase of the calculated Delta G (not equal) values from compound 1 to compound 3. The correlations between Delta G (not equal), Delta[eta(GS)-eta(TS)], (Delta S (not equal)), k(T), electrostatic model, and structural parameters have been investigated.