Prediction Of Surface Properties Research Articles

Identification of Subsurface Deformation in Machining of Inconel 718

There is considerable industrial significance to understand the nature of subsurface deformation under the machined surface for correct prediction of surface properties in machined components based upon the machined conditions and material behaviors that give rise to them. In this study, high speed machining of Inconel 718 was carried with whisker reinforced ceramic cutting tool under different conditions of tool wear, coolant state and cutting parameters. The objective of the present investigation was to determine the effect of both cutting parameters and tool wear on the plastic deformation in the subsurface region of Inconel 718 after the finishing machining with above process conditions. The surface and subsurface region of machined specimens were examined using a high resolution scan electron microscope (HRSEM) and EBSD technique, microhardness measurements were also conducted on the test samples, accordingly plastic strain analysis were carried out.

Modified PT-LJ-SAFT Density Functional Theory: I. Prediction of surface properties and phase equilibria of non-associating fluids

A new modified version of a Perturbation Density Functional Theory (PT-DFT) based on the Statistical Association Fluid Theory (SAFT) with a Lennard–Jones interaction potential is proposed to model the vapor–liquid phase equilibrium and to predict the interfacial behavior of non-associating hydrocarbon fluids. In the interaction model for the Helmholtz free energy functional the molecules are separated into m spherical segments interacting via a Lennard–Jones potential. The segments form chains of tangent spheres. In the perturbation approximation to Density Functional Theory the interaction potential is split according to WCA and the attractive term to the free energy functional consists of a suitable modification of the perturbation expression. This modification to PT-DFT yields surface tensions for the Lennard–Jones sphere fluid ( m = 1.0) which are in perfect agreement with simulation data. The new PT-DFT model combines the high flexibility of the SAFT free energy functional with a modified density functional approach that enables to perform accurate calculations of interfacial properties. To take into account the contributions to surface tension resulting from mesoscale thermal fluctuations a semiempirical model is proposed that allows to correct the microscopic intrinsic surface tension. The model is used to describe the phase equilibrium of lower alkanes and aromatics. The results demonstrate the capability to fit vapor–liquid equilibrium data and to predict very accurately the surface properties of these fluids within the uncertainties of the experimental data.

A conformation study of normal alkoxy groups introduced on to a silica surface

The molecular dynamics (MD) method and IR spectroscopy have been applied to investigate the conformations of several normal alkoxy groups grafted on a silica surface. The structures of octhyl (C8), dodecyl (C12) and octadecyl (C18) alkoxy groups at about a maximum loading value were focused on. The conclusions of the study were as follows. (i) The difference in the maximum loading values between C8 and C 18 alkoxy groups was estimated to be 20% at most, which was smaller than that expected from the bulkiness of the groups. (ii) The results of the MD simulation are nearly in accordance with those obtained by IR measurements. The fraction of that structure in the total segments of the groups introduced is constant or decreases slightly depending on their lengths. (iii) The length effect of the groups on the conformation was assumed by MD simulation. These estimations are not obtained by the experimental method. It is suggested that MD simulation is very useful for surface design and prediction of surface properties. (iv) The results of MD simulation and IR measurement demonstrate that at a higher degree of modification of a few segments near the modified sites is rigid and the terminal part of the alkoxy group is flexible.