Papers by Keyword: Surface Patterning

Abstract: Aiming to produce a pattern on the surface of austenitic stainless steel, AISI 316L, cylindrical samples were plasma nitrided with copper grids (the same are used in Transmission Electron Microscopy (TEM)) accommodated on the surface. Samples were positioned at the cathode and process was performed according to following constant parameters: temperature of 400 °C, pressure of 3 Torr and treatment time of 2h. In order to evaluate the difference in the pattern produced, three different gas mixtures were used: poor in nitrogen (5% N₂/95% H₂), rich in nitrogen (95% N₂/5% H₂) and a gas mixture with addition of argon (80% N₂/10% H₂/10% Ar). After nitriding, samples were characterized by optical interferometry (OI), scanning electron microscopy (SEM), optical microscopy (OM), micro hardness test and, X-ray diffraction (XRD). The results showed the presence of a mask (TEM grid) promotes the surface patterning of steel. This patterning is associated with high residual compressive stress induced by the introduction of a large amount of nitrogen.

Abstract: Research based on ultrasonic surface treatment (UST) shows that the operation is beneficial to tribological properties and fatigue life of mechanical structures by enhancing the surface mechanical properties, such as roughness and residual stress, through changing nanostructure induced by severe plastic deformations on the surface. The amplitude of the vibration at the processing end is essential for the treatment effect. This paper presents a way to design an UST device that can control the amplitude and vibration mode.

Abstract: It is Common Practice for Polymer-Metal Interfaces, Frequently Encountered in Microelec-Tronic Devices, to Improve Adhesion by Surface Roughening or Micro-Patterning. the Competitionbetween Adhesive Fracture and Cohesive Fracture in the Vicinity of a Patterned Interface, i.e., Inter-Face Crack Deflection, is One of these Key Mechanisms that Contribute Significantly to the Macroscopicadhesion. in this Paper, these Fracture Phenomena are Described Simultaneously by Cohesive Zoneelements with an Exponential Traction-Separation Law (TSL) for the Adhesive Failure and an Initiallyrigid, Exponentially Decaying, TSL for the Cohesive Failure. it is Demonstrated that the Conditions Atwhich Crack Kinking Occurs are Dominated by Fracture Strength Values as Opposed to the Commonlyused Fracture Toughness Values. Experimental Verification is Performed by Means of Four Point Bend-Ing Tests on Specifically Designed Micro-Patterned Polymer-Metal Samples.

Abstract: Co-continuous polymer blend has attracted broad interest in many technique fields due to its unique ability to be transferred into porous material with interconnected micro-channels. And combined with some surface patterning, it can provide material of hierarchical porous structure. A key challenge in the fabrication of material of desired morphology is the ability to control the interface movement. Here, we incorporate the thermo-geometrically controlled annealing and hot embossing to fabricate hierarchical microporous structures with well defined morphology and topography. Various novel structures demanded for many emerging applications can be created by judiciously using this newly developed technique.

Abstract: Functionalized nanoparticles have powerful applications as intermediates between solution and surface chemistry and as tools for nanofabrication. Two main examples of these have been shown. The functionalization of 3 nm gold and 55 nm silica nanoparticles with cyclodextrin (CD) host sites has been achieved, which allows: (i) the controlled aggregation with guestfunctionalized dendrimers in solution, (ii) the specific adsorption onto dendrimer-patterned substrates, and (iii) the fabrication of larger architectures using the layer-by-layer methodology. Aggregation in solution was shown to proceed through specific host-guest recognition. The adsorption onto surfaces employed so-called “molecular printboards”, which are self-assembled monolayers with the same cyclodextrin host recognition sites which allow the stable assembly of molecules and nanoparticles through multivalent host-guest interactions. CD silica nanoparticles were shown to adsorb specifically onto areas of such molecular printboards which were patterned with adamantyl-functionalized dendrimers. The layer-by-layer (LBL) assembly of such dendrimers and CD gold nanoparticles led to a controllable multilayer architecture with a thickness increase of about 2 nm per bilayer. The combination of the (bottom-up) particle LBL assembly and top-down surface structuring, in particular nanoimprint lithography, was shown to result in the formation of 3D objects down to sub-100 nm in all three dimensions.

Abstract: The paper gives an overview of recent research activities that explore new pathways to achieve selective structurization of semiconductor surfaces by electrochemical deposition or dissolution techniques. Of a particular emphasis are pathways that are based on a two step procedure: First, locally a semiconductor surface is selectively activated (or de-activated) using techniques with a high lateral resolution (focussed ion electron beam, or AFM). In a second step, an electrochemical reaction (dissolution or material deposition) is selectively carried out at sensitized surface locations. Different examples of this strategy are given including selective suppression of a surface by damage induced amorphization. Additionally, smart structuring approaches involving self-organization of deposition or dissolution processes are shortly discussed.