Rahul Basu - Academia.edu (original) (raw)
Papers by Rahul Basu
Defence Science Journal, 2002
The computer-aided design (CAD), computer-aided manufacturing (CAM) of a 3-D trunnion mount locat... more The computer-aided design (CAD), computer-aided manufacturing (CAM) of a 3-D trunnion mount located on the intercasing housing of a gas turbine engine is described. The mount carries load and thrust, hence stress-concentrating locations, like sharp edges and comers must be avoided. A program involving CAD, CAM and post-processing CAD surfaces for tool paths has been developed. Preliminary machining of a scrap aluminum piece that verified the program is described. This method is applicable to a wide variety of proprietary packages.
Effect of annealing on the properties of Cu 2 SnS 3 thin films using spin coating
Materials Today: Proceedings
Diffusion bonded specimens of Ti6Al4V were prepared as tensile test coupons by wire-cutting. Frac... more Diffusion bonded specimens of Ti6Al4V were prepared as tensile test coupons by wire-cutting. Fracture tests were performed at room temperature and temperatures up to 800ºC. The results of both the ultimate tensile stress limits and visual features by Scanning Electron Microscopy on the fracture surfaces were studied. It was found that the stress limit decreases almost linearly with temperature. The SEM surface photos showed families of intersecting lines resembling slip lines on asfractured surfaces. An Instron machine with a heating chamber and a LEO 440i SEM were used. Preliminary analyses indicated that the fracture occurs by multiple slip of certain planes intersecting the bond surface, rather than by generation of voids and vacancies. These defects were not apparent under the magnification used, for these particular specimens. By contrast, in ductile fracture, voids are clearly seen at high magnification. Normally, these combine to create sites along which fracture initiates. In this particular experiment, ledges produced by planar slip probably initiated misfit along the bond planes. The spacing between slip lines varied with the temperature at which fracture occurred. Cracks were not visible, indicating that fracture occurred by some precursor mechanism.
Indian Journal of Pure Applied Physics, 1983
Supplemental Proceedings, 2016
The compounds CdHgTe and its constituent binaries CdTe, HgTe, and CdHg are semiconductors which a... more The compounds CdHgTe and its constituent binaries CdTe, HgTe, and CdHg are semiconductors which are used in thermal, infrared, nuclear, thermoelectric and other photo sensitive devices. The compo~d CdHgTe has a Sphaleritic structure of possible type AilB:ICI1. The TERCP program of Kaufman is used to estimate the stable regions of the ternary phase diagram using available thermodynamic data. It was found that there was little variation in stochiometry with temperature. The compositions were calculated for temperatures ranging from 325K to IOOK and the compositional limits were Cd13_20Hg12_01Te75_79, Hg varying most. By comparison with a similar compound, Cd In2Te4 of forbidden band width .88 to .90 e.v., similar properties are postulated for CdlHglTe6 with applications in the infra red region of the spectrum at 300K where this composition is given by TERCP at the limit of stability. Pressure ,p Free energy for the system A ,AFA Temperature ,'I' Free energy in TERCP ,Gi Van Laars Parameters,eo e 1 e2 ep x,y,z ternary coordination Interaction parameter for the liquid phase ,L concentration in field phi ,x' Interaction parameter for the BCC phase ,B concentration in field psi, xy Enthalpy of formation ,AHf
Volume 5: Manufacturing Materials and Metallurgy; Ceramics; Structures and Dynamics; Controls, Diagnostics and Instrumentation; Education, 1998
Fibre Science and Technology, 1984
A theoretical model is jormulated to describe solid state eutectoid transjormation. Solutions inc... more A theoretical model is jormulated to describe solid state eutectoid transjormation. Solutions incorporating appropriate boundary conditions are derivedJrom transient and steady states. It is shown that the transient solution describes build-up oj the interJacial boundary layer, whereas the steady state solution extends into the phase. The presence oj this boundary layer with considerable concentration and temperature gradients suggests a solid state analogue to constitutional super cooling, as in the liquid to solid transjormation.
Fibre Science and Technology, 1984
A theoretical model is formulated to describe the processes of eutectic solidification, including... more A theoretical model is formulated to describe the processes of eutectic solidification, including diffusion and heat transfer. The effects of radial as well as axial diffusion are combined in this formulation. A non-linear differential equation is obtained which is then linearised with the aid of the steady-state solution of heat flow in the solid. Separation of variables is used to solve the steady-state differential equation. A steady-state solution is also obtained by a perturbation series using a suitable small parameter, where it is found that a thermal effect is predominant in the establishing of the boundary layer. The concentration varies rapidly across this boundary layer, found to be ... lOl~m for certain typical parametric values.
Defence Science Journal, 1986
Defence Science Journal, 2004
This paper examines a model for coupled heat and mass transfer for freezing in a porous media wit... more This paper examines a model for coupled heat and mass transfer for freezing in a porous media with Dirichlet and convective boundary conditions. Variables include porosity, heat transfer coefficients, thermal and mass diffusivity, density, latent heat, and boundary temperatures. A simulation for the slab illustrates the appearance of undercooling. A stability criterion for the phase interface is linked with well-known metallurgical parameters like undercooling and freezing rate. A possible mechanism for freckling in ingots of niobium-rich superalloys is examined. It has been shown that heat and mass transfer balance at the interface can affect stability. The effect of boundary conditions on the velocity of freezing is computed for some cases, including the self-freezing process.
Freeze-drying has received renewed interest in connection with biotechnology, food preservation a... more Freeze-drying has received renewed interest in connection with biotechnology, food preservation and chemical industries. Freeze-drying under reduced pressure causes sublimation to occur. Simultaneous freezing of the moisture phase couples the two processes of freezing and sublimation and creates a self-driven process without need for any additional application of external energy other than that required to lower the surface temperature and pressure initially. A mathematical model consisting of coupled diffusion equations describing thermal and mass equilibrium in the solid-liquid and solid-vapour regions is solved analytically. The liquid-solid region is included with unknown freezing interfacial conditions. The effects of various parameters, such as conductivity ratio, latent heats, initial concentration, surface pressure and surface temperature, are examined with respect to the freezing and sublimation rates. The freezing rate is faster than the sublimation rate, though slower than the corresponding rate for constant freezing temperature. The freezing temperature is higher than the sublimation temperature for a constant composition ice pack.
Materials Research Bulletin, 1978
The quaternary system Sb°Te-Bi-Se with small amounts of suitable dopants is of interest for the m... more The quaternary system Sb°Te-Bi-Se with small amounts of suitable dopants is of interest for the manufacture of thermoelectric modules which exhibit the Peltier and Seebeck effects. This property could be useful in the production of energy from the thermoelectric effect. Other substances are bismuth telluride (Bi2Te 3) and Sb-Te-Bi and compounds such as ZnIn2Se4. In the present paper the application of computer programs such as MIGAP of Kaufman is used to indicate the stability of the ternary limits of Sb-Te-Bi within the temperature ranges of interest, namely 273 K to 300 K.
Journal of Reinforced Plastics and Composites, 1989
Mechanical properties of some orthopaedic products—Alpha—plast, Barplasty, CFB, and Durament were... more Mechanical properties of some orthopaedic products—Alpha—plast, Barplasty, CFB, and Durament were evaluated. After polymerising into plaques, test samples were ma chined into coupons. Notched specimens were fractured under tension using the IN- STRON. Fracture toughnesses, fracture energies and tensile stresses were subsequently calculated. Fractography revealed that toughness and fracture energy correlated with duc tility and cohesion. Tougher materials tended to show more transgranular fracture, though the intergranular mode was also observed. The KEVEX unit indicated Zr and some Si was present. Dispersed non-spherical particles were also seen in SEM micrographs. Tough nesses and energies were lower than those reported earlier [1] . Voids, incoherent inter faces, larger notch widths, and lubrication by filler particles could result in lowered yield stress and toughness. The method of preparation, initial particle size distribution, and ac tivating agents also affect properties [2-5].
Journal of Reinforced Plastics and Composites, 1982
Journal of Reinforced Plastics and Composites, 1982
A theoretical model is formulated to describe the processes of diffusion and heat transfer that o... more A theoretical model is formulated to describe the processes of diffusion and heat transfer that occur in eutectoid solidification. Radial as well as unidirectional solute diffusion are considered in this formulation. The resultant non-linear differential equation is then linearised with the aid of the steady state solution of the heat flow equation in the solid. Evaluation of the order of magnitude of parameters occuring in this equation indicates the radial contribution to be dominant in the growth of the secondary fiber eutectic(oid) phase. Separation of variables and perturbation solutions using a suitable small parameter are then used to evaluate the steady state solution. It is found that a boundary layer exists where the concentration varies rapidly from the interface to the steady state value in the fiber, within a very small distance, about 10 microns. The boundary layer thickness and concentration differential across it are evaluated for a typical case.
Journal of Reinforced Plastics and Composites, 1983
A theoretical model is formulated to describe solid state eutectoid transformation. Solutions inc... more A theoretical model is formulated to describe solid state eutectoid transformation. Solutions incorporating appropriate boundary conditions are derived for transient and steady states. It is shown that the transient solution describes build up of the interfacial boundary layer, whereas the steady state solution extends into the phase. The presence of this boundary layer with considerable concentration and temperature gradients sug gests a solid state analogue to constitutional super cooling, as in the liquid to solid transformation.
Journal of Physics and Chemistry of Solids, 1981
The use of dislocation measurements in Zinc single crystals reveals the presence of a yield point... more The use of dislocation measurements in Zinc single crystals reveals the presence of a yield point or flow stress corresponding to a Stages III (elastic to elastic-plastic) transition. This is commonly attributed to the presence of interstitials such as N. The mathematical models of Seeger ...
Defence Science Journal, 2002
The computer-aided design (CAD), computer-aided manufacturing (CAM) of a 3-D trunnion mount locat... more The computer-aided design (CAD), computer-aided manufacturing (CAM) of a 3-D trunnion mount located on the intercasing housing of a gas turbine engine is described. The mount carries load and thrust, hence stress-concentrating locations, like sharp edges and comers must be avoided. A program involving CAD, CAM and post-processing CAD surfaces for tool paths has been developed. Preliminary machining of a scrap aluminum piece that verified the program is described. This method is applicable to a wide variety of proprietary packages.
Effect of annealing on the properties of Cu 2 SnS 3 thin films using spin coating
Materials Today: Proceedings
Diffusion bonded specimens of Ti6Al4V were prepared as tensile test coupons by wire-cutting. Frac... more Diffusion bonded specimens of Ti6Al4V were prepared as tensile test coupons by wire-cutting. Fracture tests were performed at room temperature and temperatures up to 800ºC. The results of both the ultimate tensile stress limits and visual features by Scanning Electron Microscopy on the fracture surfaces were studied. It was found that the stress limit decreases almost linearly with temperature. The SEM surface photos showed families of intersecting lines resembling slip lines on asfractured surfaces. An Instron machine with a heating chamber and a LEO 440i SEM were used. Preliminary analyses indicated that the fracture occurs by multiple slip of certain planes intersecting the bond surface, rather than by generation of voids and vacancies. These defects were not apparent under the magnification used, for these particular specimens. By contrast, in ductile fracture, voids are clearly seen at high magnification. Normally, these combine to create sites along which fracture initiates. In this particular experiment, ledges produced by planar slip probably initiated misfit along the bond planes. The spacing between slip lines varied with the temperature at which fracture occurred. Cracks were not visible, indicating that fracture occurred by some precursor mechanism.
Indian Journal of Pure Applied Physics, 1983
Supplemental Proceedings, 2016
The compounds CdHgTe and its constituent binaries CdTe, HgTe, and CdHg are semiconductors which a... more The compounds CdHgTe and its constituent binaries CdTe, HgTe, and CdHg are semiconductors which are used in thermal, infrared, nuclear, thermoelectric and other photo sensitive devices. The compo~d CdHgTe has a Sphaleritic structure of possible type AilB:ICI1. The TERCP program of Kaufman is used to estimate the stable regions of the ternary phase diagram using available thermodynamic data. It was found that there was little variation in stochiometry with temperature. The compositions were calculated for temperatures ranging from 325K to IOOK and the compositional limits were Cd13_20Hg12_01Te75_79, Hg varying most. By comparison with a similar compound, Cd In2Te4 of forbidden band width .88 to .90 e.v., similar properties are postulated for CdlHglTe6 with applications in the infra red region of the spectrum at 300K where this composition is given by TERCP at the limit of stability. Pressure ,p Free energy for the system A ,AFA Temperature ,'I' Free energy in TERCP ,Gi Van Laars Parameters,eo e 1 e2 ep x,y,z ternary coordination Interaction parameter for the liquid phase ,L concentration in field phi ,x' Interaction parameter for the BCC phase ,B concentration in field psi, xy Enthalpy of formation ,AHf
Volume 5: Manufacturing Materials and Metallurgy; Ceramics; Structures and Dynamics; Controls, Diagnostics and Instrumentation; Education, 1998
Fibre Science and Technology, 1984
A theoretical model is jormulated to describe solid state eutectoid transjormation. Solutions inc... more A theoretical model is jormulated to describe solid state eutectoid transjormation. Solutions incorporating appropriate boundary conditions are derivedJrom transient and steady states. It is shown that the transient solution describes build-up oj the interJacial boundary layer, whereas the steady state solution extends into the phase. The presence oj this boundary layer with considerable concentration and temperature gradients suggests a solid state analogue to constitutional super cooling, as in the liquid to solid transjormation.
Fibre Science and Technology, 1984
A theoretical model is formulated to describe the processes of eutectic solidification, including... more A theoretical model is formulated to describe the processes of eutectic solidification, including diffusion and heat transfer. The effects of radial as well as axial diffusion are combined in this formulation. A non-linear differential equation is obtained which is then linearised with the aid of the steady-state solution of heat flow in the solid. Separation of variables is used to solve the steady-state differential equation. A steady-state solution is also obtained by a perturbation series using a suitable small parameter, where it is found that a thermal effect is predominant in the establishing of the boundary layer. The concentration varies rapidly across this boundary layer, found to be ... lOl~m for certain typical parametric values.
Defence Science Journal, 1986
Defence Science Journal, 2004
This paper examines a model for coupled heat and mass transfer for freezing in a porous media wit... more This paper examines a model for coupled heat and mass transfer for freezing in a porous media with Dirichlet and convective boundary conditions. Variables include porosity, heat transfer coefficients, thermal and mass diffusivity, density, latent heat, and boundary temperatures. A simulation for the slab illustrates the appearance of undercooling. A stability criterion for the phase interface is linked with well-known metallurgical parameters like undercooling and freezing rate. A possible mechanism for freckling in ingots of niobium-rich superalloys is examined. It has been shown that heat and mass transfer balance at the interface can affect stability. The effect of boundary conditions on the velocity of freezing is computed for some cases, including the self-freezing process.
Freeze-drying has received renewed interest in connection with biotechnology, food preservation a... more Freeze-drying has received renewed interest in connection with biotechnology, food preservation and chemical industries. Freeze-drying under reduced pressure causes sublimation to occur. Simultaneous freezing of the moisture phase couples the two processes of freezing and sublimation and creates a self-driven process without need for any additional application of external energy other than that required to lower the surface temperature and pressure initially. A mathematical model consisting of coupled diffusion equations describing thermal and mass equilibrium in the solid-liquid and solid-vapour regions is solved analytically. The liquid-solid region is included with unknown freezing interfacial conditions. The effects of various parameters, such as conductivity ratio, latent heats, initial concentration, surface pressure and surface temperature, are examined with respect to the freezing and sublimation rates. The freezing rate is faster than the sublimation rate, though slower than the corresponding rate for constant freezing temperature. The freezing temperature is higher than the sublimation temperature for a constant composition ice pack.
Materials Research Bulletin, 1978
The quaternary system Sb°Te-Bi-Se with small amounts of suitable dopants is of interest for the m... more The quaternary system Sb°Te-Bi-Se with small amounts of suitable dopants is of interest for the manufacture of thermoelectric modules which exhibit the Peltier and Seebeck effects. This property could be useful in the production of energy from the thermoelectric effect. Other substances are bismuth telluride (Bi2Te 3) and Sb-Te-Bi and compounds such as ZnIn2Se4. In the present paper the application of computer programs such as MIGAP of Kaufman is used to indicate the stability of the ternary limits of Sb-Te-Bi within the temperature ranges of interest, namely 273 K to 300 K.
Journal of Reinforced Plastics and Composites, 1989
Mechanical properties of some orthopaedic products—Alpha—plast, Barplasty, CFB, and Durament were... more Mechanical properties of some orthopaedic products—Alpha—plast, Barplasty, CFB, and Durament were evaluated. After polymerising into plaques, test samples were ma chined into coupons. Notched specimens were fractured under tension using the IN- STRON. Fracture toughnesses, fracture energies and tensile stresses were subsequently calculated. Fractography revealed that toughness and fracture energy correlated with duc tility and cohesion. Tougher materials tended to show more transgranular fracture, though the intergranular mode was also observed. The KEVEX unit indicated Zr and some Si was present. Dispersed non-spherical particles were also seen in SEM micrographs. Tough nesses and energies were lower than those reported earlier [1] . Voids, incoherent inter faces, larger notch widths, and lubrication by filler particles could result in lowered yield stress and toughness. The method of preparation, initial particle size distribution, and ac tivating agents also affect properties [2-5].
Journal of Reinforced Plastics and Composites, 1982
Journal of Reinforced Plastics and Composites, 1982
A theoretical model is formulated to describe the processes of diffusion and heat transfer that o... more A theoretical model is formulated to describe the processes of diffusion and heat transfer that occur in eutectoid solidification. Radial as well as unidirectional solute diffusion are considered in this formulation. The resultant non-linear differential equation is then linearised with the aid of the steady state solution of the heat flow equation in the solid. Evaluation of the order of magnitude of parameters occuring in this equation indicates the radial contribution to be dominant in the growth of the secondary fiber eutectic(oid) phase. Separation of variables and perturbation solutions using a suitable small parameter are then used to evaluate the steady state solution. It is found that a boundary layer exists where the concentration varies rapidly from the interface to the steady state value in the fiber, within a very small distance, about 10 microns. The boundary layer thickness and concentration differential across it are evaluated for a typical case.
Journal of Reinforced Plastics and Composites, 1983
A theoretical model is formulated to describe solid state eutectoid transformation. Solutions inc... more A theoretical model is formulated to describe solid state eutectoid transformation. Solutions incorporating appropriate boundary conditions are derived for transient and steady states. It is shown that the transient solution describes build up of the interfacial boundary layer, whereas the steady state solution extends into the phase. The presence of this boundary layer with considerable concentration and temperature gradients sug gests a solid state analogue to constitutional super cooling, as in the liquid to solid transformation.
Journal of Physics and Chemistry of Solids, 1981
The use of dislocation measurements in Zinc single crystals reveals the presence of a yield point... more The use of dislocation measurements in Zinc single crystals reveals the presence of a yield point or flow stress corresponding to a Stages III (elastic to elastic-plastic) transition. This is commonly attributed to the presence of interstitials such as N. The mathematical models of Seeger ...