Fabrication of micro-structured tools for the production of curved metal surfaces by pulsed electrochemical machining

A new, scalable process chain for the fabrication of curved micro-structured metallic tools is developed and evaluated. Arrays of arrows, circles, semicircles and rings with final lateral dimensions of 124 to 819 µm are realised on the tools and successfully transmitted in one process step to stainless steel workpieces with a functional area of 6.5 cm2 using pulsed electrochemical machining. Photolithography-etching or micromilling are applied as initial micro-structuring processes, resulting in micro-structured master forms. These forms are copied into reusable silicon forms. This is followed by epoxy casting and electroforming to obtain the final tools. The tools are made of Nickel and have a diameter of 34 mm. Whilst micromilling, photolithography, silicon casting, epoxy casting and electroforming copy the structures very precisely, the wet etching process induces a widening of the dimensions due to the isotropic character of the process. The advantage of the process chain is the reusability of the master as well as of the silicone forms, which can be copied very precisely and easily with scalable processes to get precision tools with relatively large micro-structured areas. The reusability of the forms makes the fabrication of micro-structured tools relatively cost-efficient. The use of photolithography as the initial structuring process enables the generation of arbitrary, user-defined geometries for the micro-structures on the tool surface. The process chain described has the potential to fabricate lateral structure sizes on tools down to one micrometre.

Combined specular and off-specular reflectometry: elucidating the complex structure of soft buried interfaces

Neutron specular reflectometry (SR) and off-specular scattering (OSS) are nondestructive techniques which, through deuteration, give a high contrast even among chemically identical species and are therefore highly suitable for investigations of soft-matter thin films. Through a combination of these two techniques, the former yielding a density profile in the direction normal to the sample surface and the latter yielding a depth-resolved in-plane lateral structure, one can obtain quite detailed information on buried morphology on length scales ranging from the order of ångströms to ∼10 µm. This is illustrated via quantitative evaluation of data on SR and OSS collected in time-of-flight (ToF) measurements of a set of films composed of immiscible polymer layers, protonated poly(methyl methacrylate) and deuterated polystyrene, undergoing a decomposition process upon annealing. Joint SR and OSS data analysis was performed by the use of a quick and robust originally developed algorithm including a common absolute-scale normalization of both types of scattering, which are intricately linked, constraining the model to a high degree. This, particularly, makes it possible to distinguish readily between different dewetting scenarios driven either by the nucleation and growth of defects (holes, protrusions etc.) or by thermal fluctuations in the buried interface between layers. Finally, the 2D OSS maps of particular cases are presented in different spaces and qualitative differences are explained, allowing also the qualitative differentiation of the in-plane structure of long-range order, the correlated roughness and bulk defects by a simple inspection of the scattering maps prior to quantitative fits.

Glacial isostatic adjustment of the pacific coast of North America: The Influence of lateral earth structure

Summary The Pacific Coast of Central North America is a geodynamically complex region which has been subject to various geophysical processes operating on different time scales. Glacial isostatic adjustment (GIA), the ongoing deformational response of the solid Earth to past deglaciation, is an important geodynamic process in this region. In this study we apply Earth models with 3D structure to determine if the inclusion of lateral structure can explain the poor performance of 1D models in this region. Three different approaches are used to construct 3D models of the Earth structure. For the first approach, we adopt an optimal 1D viscosity structure from previous work and add lateral variations based on four global seismic shear wave velocity anomalies and two global lithosphere thickness models. The results based on these models indicate that the addition of lateral structure significantly impacts modelled RSL changes, but the data-model fits are not improved. The global seismic models are limited in spatial resolution and so two other approaches were considered to produce higher resolution models of 3D structure: inserting a regional seismic model into two of the global seismic models and, explicitly incorporating regional structure of the Cascadia subduction zone and vicinity, i.e. the subducting slab, the overlying mantle wedge, and the plate boundary interface. The results associated with these higher resolution models do not reveal any clear improvement in satisfying the RSL observations, suggesting that our estimates of lateral structure are inaccurate and/or the data-model misfits are primarily due to limitations in the adopted ice-loading histories. The different realisations of 3D Earth structure gives useful insight to uncertainty associated with this aspect of the GIA model. Our results indicate that improving constraints on the deglacial history of the southwest sector of the Cordilleran ice sheet is an important step towards developing more accurate of GIA models for this region.

Hybridization vs decoupling: influence of an h-BN interlayer on the physical properties of a lander-type molecule on Ni(111)

2D materials such as hexagonal boron nitride (h-BN) are widely used to decouple organic molecules from metal substrates. Nevertheless, there are also indications in the literature for a significant hybridization, which results in a perturbation of the intrinsic molecular properties. In this work we study the electronic and optical properties as well as the lateral structure of tetraphenyldibenzoperiflanthene (DBP) on Ni(111) with and without an atomically thin h-BN interlayer to investigate its possible decoupling effect. To this end, we use in situ differential reflectance spectroscopy as an established method to distinguish between hybridized and decoupled molecules. By inserting an h-BN interlayer we fabricate a buried interface and show that the DBP molecules are well decoupled from the Ni(111) surface. Furthermore, a highly ordered DBP monolayer is obtained on h-BN/Ni(111) by depositing the molecules at a substrate temperature of 170 °C. The structural results are obtained by quantitative low-energy electron diffraction and low-temperature scanning tunneling microscopy. Finally, the investigation of the valence band structure by ultraviolet photoelectron spectroscopy shows that the low work function of h-BN/Ni(111) further decreases after the DBP deposition. For this reason, the h-BN-passivated Ni(111) surface may serve as potential n-type contact for future molecular electronic devices.

Preparation, Characterization, Morphological and Particle Properties of Crystallized Palm-Based Methyl Ester Sulphonates (MES) Powder

Methyl ester sulphonates (MES) have been considered as an alternative green surfactant for the detergent market. Investigation on the purification of methyl ester sulphonates (MES) with various carbon chains of C12, C14, C16 and C16–18 derived from palm methyl ester is of great interest. These MES powders have been repeatedly crystallized with ethanol and the purity of MES has increased to a maximum of 99% active content and 96% crystallinity index without changing the structure. These crystallized MES with high active content have 1.0% to 2.3% moisture content and retained its di-salt content in the range of 5%. The crystallized MES C16 and C16–18 attained excellent flow characteristics. Morphology, structural and its crystallinity analyses showed that the crystals MES had good solubility properties, stable crystal structure (β polymorphic) and triclinic lateral structure when it is in high active content. The brittleness of MES crystals increased from a β’ to a β subcell. Crystal with high brittleness has the potential to ease production of powder, which leads to a reduction in the cost of production and improves efficiency.