Function Of Interlayer Thickness Research Articles

Study of the Role of Titanium and Iron Cathodic Cages on Plasma-Nitrided AISI 430 Ferritic Stainless Steel.

In contrast to austenitic and martensitic stainless steels, ferritic stainless steels have a lower hardness and wear resistance but exhibit excellent corrosion resistance. Due to this fact, their use in the aerospace, automobile, and house construction industries is restricted. Several methods have been utilized to enhance the tribological characteristics of ferritic stainless steels. In this work, titanium nitride coating has been carried out by using a cathodic cage of titanium material, and later on, the titanium cathodic cage is replaced by an AISI-304 cathodic cage in a CCPN chamber to form iron nitride coating on AISI-430 ferritic stainless steel coupons through a plasma nitriding process for 4 h at a fixed temperature of 400 °C. The microstructures and mechanical traits of all processed and control coupons were analyzed using scanning electron microscopy, X-ray diffraction, ball-on-disc wear tester, and microhardness tester techniques. The results showed that hardness increased up to 1489 HV with the titanium cage, which is much higher than the hardness of the base material (270 HV). The titanium cage-treated coupons have high layer thickness, smooth surface morphology, and a minimum crystallite size of 2.2 nm. The wear rate was reduced up to 50% over the base material after the titanium cage plasma treatment. The base coupon exhibited severe abrasive wear, whereas nitrided coupons exhibited dominant adhesive wear. In the iron nitride coatings, this effect is also important, owing to the more influential cleaning process in a glow discharge, and the better adhesion with enhanced interlayer thickness is attributed to the fact that the compliance of the interlayer minimizes shear stresses at the coating–substrate interface. The use of a graded interface improves adhesion compared with the case where no interlayer is used but a titanium interlayer of comparable thickness provides a significant increase in measured adhesion. For both titanium and iron nitride films, there is a reduction in wear volume which is a function of interlayer thickness; this will have a substantial effect on wear lifetime. Thus by careful control of the interlayer thickness and composition, it should be possible to improve coating performance in tribological applications.

Effect of Polymeric Interlayer on Wave Propagation in Transparent Soda-lime Glass

The transparent armor and aircraft windshields are comprising of glass or transparent ceramic laminates joined with the polymeric interlayer. The interlayer thickness plays a vital role in improving the damage, impact, and wave propagation response of transparent laminates. The edge-on-impact simulations on monolithic ballistic soda-lime glass are performed first to investigate and verify the wave propagation using ANSYS/Autodyn. Secondly, to lessen the wave speed and damage area in the glass, the different thicknesses of PU interlayer were incorporated in the numerical model and analyzed. The delay time in wave arrival time as a function of interlayer thickness was estimated. Additionally, the influence of PU interlayer orientations and a number of layers (single & double) on longitudinal wave propagation and damage are also studied numerically and discussed.

Fracture Toughness of TiN Coating as a Function of Interlayer Thickness

Single layer TiN and Ti/TiN bilayers were deposited on H-13 steel by plasma enhanced chemical vapor deposition technique. TiN thickness was kept constant at 2 μm and Ti thickness values ranged between 100 nm to 1 μm. Fracture toughness and residual stress of TiN coatings was measured as functions of thickness of titanium interlayer. Vickers indentation tests, X-ray diffraction, optical microscopy and field emission scanning electron microscopy were used to characterize the coatings. Results showed fracture toughness of the coating increases severely by increasing interlayer thickness. Additionally, internal stress which causes debonding and breaking of the entire coating, reduces about 70% by increasing interlayer thickness up to 600 nm. Moreover, there is maximum value for interlayer thickness in order to optimize fracture toughness of the coating.

Influence of interlayer thickness of a thin noble metal MSIP-PVD coating on compound and system properties for glass lens moulding

The replicative production of complex optical lenses made of glass has become very important over the last decades. The technology precision glass moulding has a great potential to fulfil the optical demands on high surface quality, small tolerances and high uniformity of glass lenses at high production volumes. A noble metal MSIP-PVD coating is used to increase lifetime of the precision moulds. Beside the chemical resistance and protection of the moulds against the hot glass, prevention of glass sticking and oxidation adhesion between coating and substrate is of great importance. As state-of-the-art a noble metal coating based on platinum and iridium is used with a nickel interlayer. As a result of previously presented research replacement of the nickel interlayer by a chromium interlayer has increased adhesion between coating and substrate significantly. The present research work shows an increase of this adhesion as a function of interlayer thickness. Application oriented heating tests show an influence of the interlayer on the glass behaviour during the heating cycle due to a diffusion process between interlayer and toplayer. A coating system of 20 nm Cr interlayer and 300 nm Pt40Ir60 function layer exhibits a good combination between good compound adhesion and little influence on the glass behaviour.

Effect of Ni–Al2O3 nanocompositecoating thickness on transient liquid phase bonding of Al 6061 MMC

Transient liquid phase diffusion bonding of Al 6061 containing 15 vol.-%alumina particles was carried out as a function of interlayer thickness. ElectrodepositedNi coatings containing 18 vol.-% nanosized alumina particles with thicknessranging from 1 to 13 μm was used as the interlayer. Joint formation wasattributed to the solid state diffusion of Ni into the Al 6061 metal matrixbase metal followed by eutectic formation, base metal dissolution and isothermalsolidification at the joint interface. Examination of the joint region usingscanning electron microscopy, wavelength dispersive spectroscopy and X-raydiffraction showed the formation of intermetallic phases such as AlFe3Si,Ni17Al3·9Si5·1O48and Ni3Si within the joint zone. The results indicated that a maximumjoint strength of 92% of the base metal shear strength can be obtainedif an 11 μm thick Ni–Al2O3 nanocomposite coatingis used as the interlayer.

Characterization of Oxide Materials for Exchange Decoupling in Perpendicular Thin Film Media

We report on continued measurements using an experimental model system to quantify intergranular exchange coupling in CoCrPt-oxide perpendicular magnetic recording media. A thin film multi-layered structure comprising a high coercivity CoPt unicrystal layer separated from a low coercivity CoPt layer by a thin oxide interlayer is used to model the vertically aligned grains separated by oxide boundaries in CoCrPt-oxide media. Exchange coupling is measured by field shifts of the minor loop from the low coercivity layer. Results on coupling energy as a function of interlayer thickness are presented for several different oxides. Additional measurements are presented to understand the possible role of the added alloying elements, Cr and Mn, to the magnetic grains in terms of intergranular exchange coupling.

Influence of alloy composition and interlayer thickness on twist and tilt mosaic in AlxGa1−xN/AlN/GaN heterostructures

High-resolution x-ray diffraction, in surface symmetric, skew symmetric, and grazing incidence in-plane diffraction geometries, has been used to investigate the effect of an AlN interlayer between micron thick GaN and AlxGa1−xN layers grown by metalorganic vapor phase epitaxy on basal plane sapphire. No change is found in the tilt mosaic (threading screw dislocation density) with thickness or Al fraction x of the upper layer. A linear increase in the twist mosaic (threading edge dislocation density) was observed as a function of interlayer thickness and x. For all samples the twist mosaic of the AlGaN was significantly greater, by at least a factor of two, than that of the GaN layer. With increasing interlayer thickness the in-plane lattice parameter of the AlGaN decreased. The results are explained in terms of extra threading edge dislocations resulting from relaxation at the GaN/AlN interface.

Determination of the Exchange Coupling Strengths for Fe/Au/Fe

We measure, as a function of interlayer thickness, the magnitude of the bilinear exchange coupling in an Fe/Au/Fe trilayer, to investigate the existing order of magnitude discrepancy between theory and experiment. We use Fe whisker substrates, scanning electron microscopy polarization analysis, and reflection high-energy electron diffraction to monitor the sample's magnetic and physical structure, and confocal magneto-optical Kerr effect to determine the coupling. We determine the exchange coupling strengths of the individual oscillating terms. The total bilinear coupling strength is $\ensuremath{-}1.9\ifmmode\pm\else\textpm\fi{}0.2\mathrm{mJ}/{\mathrm{m}}^{2}$, for a Au interlayer thickness of 4 monolayers, in substantial agreement with current theory.

Exchange-coupled MBE-grown Co/Cu/Co(111) trilayers

It is shown that the high-field curvature in the in-plane and polar magnetization curves of exchange-coupled MBE-grown Co/Cu/Co(111) structures can be accurately fitted by assuming a sizeable biquadratic coupling in addition to the bilinear coupling, and the existence of a large areal fraction of ferromagnetic inclusions. Measurements on a sample with a single Co layer confirm that the curvature does not originate from the individual Co layers. Analysis of two Co/Cu/Co(111) trilayers with different CoCu interface qualities, as measured by NMR, shows significantly higher bilinear and biquadratic coupling strengths for the trilayer with the better defined CoCu interfaces. While NMR indicates reasonably good structural quality on a short lateral length scale, polar Kerr measurements as a function of interlayer thickness, and polarized neutron reflection measurements, indicate the existence of structural imperfections on a long lateral length scale.

High-field polar MOKE magnetometry as a probe of interlayer exchange coupling in MBE-grown Co/Cu/Co(111) and Fe/Cr/Fe(001) wedged trilayers

We discuss the use of room temperature polar magneto-optic Kerr effect (MOKE) measurements at high field (≤7 T) in investigating antiferromagnetic (AFM) and ferromagnetic (FM) exchange coupling in MBE-grown wedged trilayers. In the case of Co/Cu/Co(111), the polar MOKE revealed the first AFM coupling peak at 9 Å Cu thickness and the second weaker AFM coupling peak at 20 Å. This is an important result because it helps in resolving the present controversy over whether oscillatory coupling exists in (111) oriented MBE-grown Co/Cu/Co structures. For Fe/Cr/Fe(001), polar MOKE is found to be less sensitive than in-plane MOKE for extracting the detailed form of the coupling. However, polar MOKE reveals additional variations in the perpendicular saturation fields as a function of interlayer thickness, which are not found in the in-plane MOKE saturation fields.

Quantum well States in Fe (100) Ultrathin Films Observed by Magneto-Optical Effect

ABSTRACTWe report on the Magneto-optical Kerr rotation (<φ>K) spectra of ultrathin Fe films on Au or Ag (100) substrates and the φK oscillation due to interlayer thickness in Fe/Au/Fe sandwich films. In 3.5–4.5 eV, a new φK peak appears in the bcc-Fe (100) ultrathin films on the fcc-Au (100) surface and it shifts towards the higher energy side with increasing Fe layer thickness. The absolute value of eXy for 3Å (2ML) thick Fe layers is twice as large as that of bulk Fe at 3.7 eV. The thickness dependence of the transition energy of this new peak in the spectra is well explained by the concept of quantum well states in the Fe ultrathin layers, attributing the new transition to a transition from the majority spin Δ5 band ({px±i py), {dxz±i dyZ}; M=±l) to the Δ1 quantum well states (s, pz, dz2; M=0). The new peak is also observed in the Fe/Au (100) artificial superlattices. Using the εxy obtained experimentally for the Fe ultrathin films and the εxy of literature, we can reproduce the experimental φK spectra of the artificial superlattices by optical calculation. On the other hand, we cannot observe the same behavior for the ultrathin Fe films grown on a fcc-Ag (100) surface and covered by a Au (100) ultrathin film, although the εXy of Fe is different from that of the bulk and shows some structures in 2–3 eV. These structures around 2.5 eV are thought to be due to polarized Au atoms adjacent to an Fe layer.An oscillation of φK as a function of interlayer thickness, d, was observed in photon energy region between about 2.5 and 3.8 eV for the Fe (6Å) /Au (dÅ) /Fe (6A) sandwiched film. The oscillation period was about 10Å (5ML) of Au. The oscillation is thought to be closely related with a formation of spin polarized quantum well states of Δ1 band in Au layers sandwiched by magnetic layers.

Spin wave resonance study of exchange-coupled Ni 80Fe 20 double layers separated by thin interlayers of Cu, Cr and Pd

We have performed ferromagnetic resonance measurements on thin polycrystalline Ni 80Fe 20 (permalloy) double layers with interlayers of Cu, Cr and Pd. Furthermore, a mathematical model is presented, which allows a calculation of resonance fields in the parallel configuration. Comparison of the calculated and measured resonance field values yields an interlayer exchange coupling constant A 12 as a function of interlayer thickness d. We observe exponential dependencies of A 12 on d for Cr, Cu and Pd interlayers with the strongest decay for Cr. Additionally, we present FMR measurements and calculations for a Ni 80Fe 20/Cr/Co heterostructure layer system.