Brushing, mechanical methods

Mechanical cleaning includes scrubbing, scraping, brushing, mechanical shocking, and ultrasonic procedures. Scrubbing with a bristle brush and a mild abrasive is the most widely used of these methods the others are used principally as supplements to remove heavily encrusted corrosion products before scrubbing. Care should be used to avoid the removal of sound metal. 

This contamination, as in aluminum, is called smut. The usual method for desmutting is to wipe the work piece after rinsing, while it is still wet or to brush mechanically with a stiff wire bristle brush. However, it has been found that only a portion of the smut is removed by these methods and chemical etches are required to remove all of the material. An example of smut on stainless steel is shown in Figure 5 (12), where a surface which had been treated in hot sulfuric acid is shown. 

After removal from the soaking tanks, the concretions were removed from the artefacts. For large items such as the guns, this was mostly carried out by mechanical methods, using chisels or scalpels. Light concretions on small artefacts were not touched as they were either removed during conservation or were easily brushed off after removal from the furnace. The final pretreatment were to make quite sure that the barrel of the guns was clean so that the atmosphere within the furnace could freely reach all parts. 

The various mechanical methods depend on the abrasive action of wire brushes, sand and emery papers, abrasive pads (e.g. 

Mechanical methods (wire brushing, steel wool, abrasives) of cleaning rolled zinc are rarely acceptable. Areas cleaned by such methods tend to contrast... 

All oil, grease and other soluble contamination should be removed by solvent degreasing or alkaline cleaning. Rust, scale and other non-soluble contaminants should be removed by mechanical or chemical methods. Grit blasting is the most commonly used mechanical method, but wheel abrasion, grinding, wire brushing, emery cloth or steel wool can be used. Chemosil 211 primer should be applied as soon as possible after the surface preparation to reduce the risk of contamination or oxidation of the substrate. 

Abrasive cleaning. Mechanical methods for surface preparation include sandblasting, wire brushing, and abrasion with sandpaper, emery cloth, or metal wool. These methods are most effective for removing heavy, loose particles such as dirt, scale, tarnish, and oxide layers. 

An understanding of the recognition of chirality at a molecular level has become of interest in many fields of chemistry and biology. In the past decade, many attempts to clarify the mechanism of chiral recognition on CSPs for liquid chromatography have been made by means of chromatography, NMR spectroscopy,199 202 X-ray analysis, and computational methods.203 - 206 The successful studies have been mostly carried out for the small-molecule CSPs, especially cyclodextrin-based CSPs and Pirkle-type (brush-type) CSPs. In contrast, only a few mechanistic studies on chiral discrimination at the molecular... 

A successful theoretical description of polymer brushes has now been established, explaining the morphology and most of the brush behavior, based on scaling laws as developed by Alexander [180] and de Gennes [181]. More sophisticated theoretical models (self-consistent field methods [182], statistical mechanical models [183], numerical simulations [184] and recently developed approaches [185]) refined the view of brush-type systems and broadened the application of the theoretical models to more complex systems, although basically confirming the original predictions [186]. A comprehensive overview of theoretical models and experimental evidence of polymer bmshes was recently compiled by Zhao and Brittain [187] and a more detailed survey by Netz and Adehnann [188]. 

Minimize surface roughness to limit sites at which particles can adhere. This point is especially true for small particles and removal methods exploiting mechanical means. A rough surface can shield small particles from momentum transferal from brushes. 

Amylose brushes (a layer consisting of polymer chains dangling in a solvent with one end attached to a surface is frequently referred to as a polymer brush) on spherical and planar surfaces can have several advantageous uses, such as detoxification of surfaces etc. The modification of surfaces with thin polymer films is widely used to tailor surface properties such as wettability, biocompatibility, corrosion resistance, and friction [142-144]. The advantage of polymer brushes over other surface modification methods like self-assembled monolayers is their mechanical and chemical robustness, coupled with a high degree of synthetic flexibility towards the introduction of a variety of functional groups. 

Many of the finishes applied to other types of metal products can also be applied to zinc die castings, although some differences in formulation as well as occasional differences in method of application may be desirable. The types of finishes applicable to zinc die castings include mechanical finishes (buffed, polished, brushed, and tumbled) electrodeposited finishes (copper, nickel, chromium, brass, silver, and black nickel) chemical finishes (chromale, phosphate, molybdate and black nickel) and organic finishes (enamel, lacquer, paint and varnish, and plastic finishes). Electrodeposited coatings of virtually any metal capable of electrodeposition can be applied to zinc die castings. 

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