Methods of Surface Preparation

Several methods are in practice for preparing the metal surfaces before rubber lining such as follows  

Cleaning with hand tools Cleaning with power tools Cleaning by sand blasting Cleaning by water blasting and 

Cleaning with steam, high pressure water and chemicals Pickling with acid 

Cleaning by hand tools is the oldest process. Today this is employed only when power tools are not available and where the surface is inaccessible to power tools and too small. The generally used hand tools are wire brush, scraper blades and chipping hammer and emery or sand paper. Hand held electric or pneumatic power tools for cleaning include sanders, pneumatic scalers, needle gun and rotary steel brushes. 

A near white surface finish corresponds to Swedish standard Sa 2-1/2 or BS4232 second quality. This finish is defined as one from which is removed all oil, grease, dirt, mill scale, rust, corrosion products, oxides remaining coatings, except for a very light shadows of light streak discolouration. At least 95% of the surface shall have the appearance of a white metal surface finish and the remainder shall be limited to light discolouration. 

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The following alternative methods of surface preparation can be used for new concrete. 

Surface preparation is of prime importance, and optimum performance of modern protection coatings can be achieved only if the surface of the steel has been adequately treated. The method of surface preparation depends on the shape and size of the structure or component. Thus it is preferable to blast-clean an openwork steel structure by manual methods, since with this type of structure automatic blast cleaning would lead to excessive impingement of the abrasive on the machine itself. 

The possible methods of surface preparation before painting hot rolled steel are discussed in the following sections. 

This is the most important and most widely used mechanical method of surface preparation. Originally, sand was used as an abrasive but now, because of the hazard to health, it has already been replaced in the UK by metal or non-silicon materials. There are two main types of process. 

Pickling as a method of surface preparation is generally carried out by immersing the steel in an acid bath and then rinsing with clean water. It is essentially a works process because it must be carefully controlled. Site application of acid washes, etc, is not recommended. 

These remarks apply as well to the treatment of the surfaces of specimens to be used in tests in corrosion research projects, except here selection of a particular method of surface preparation is required so as to achieve reproducibility of results from test to test and amongst different investigators. Methods of preparing specimens are described in ASTM Gl 1988 and ISO 7539-1 1987. 

In contrast to the successful implementation of the bead method in studying the anomalous features, the contributions from studies with UHV-electrochemical systems has been limited to just a few. Subsequent work from our apparatus following corroboration of Clavilier s results concentrated on the effect of potential cycling through "oxide formation potential on the surface structure (19). and later on the effect of pH and type of anion (Wagner, F.T. Ross, P.N., J. Electroanal. Chem.. in press) on the anomalous features. Using the system in Yeager s laboratory, Hanson (20) was able to reproduced Clavilier s voltammetry not only for the (111) surface, but also the (100) and (110) surfaces as well. In spite of the relatively small number of contributions to the literature that have come from the UHV-electrochemical systems, they have made and essential validation of the bead method of surface preparation, and have verified the structure sensitivity of the anomalous features inferred from purely electrochemical observations. 

These tests are useful as a screening test to evaluate new bonding agents and methods of surface preparation. It must be remembered that polyesters have a bond strength three times that of polyethers. 

Oxidative stability depends on the adherend surface as well as on the adhesive itself. Some metal adhesive interfaces are chemically capable of accelerating the rate of oxidation. For example, it has been found that nearly all types of structural adhesives exhibit better thermal stability when bonded to glass or aluminum than when bonded to stainless steel or titanium.12 For any given metal, the method of surface preparation can also determine oxide characteristics, and hence bond durability. Thus, the use of primers is common practice with high-temperature structural adhesives. 

Resistance of the adhesive joint to salt climates depends not only on the type of adhesive but also on the method of surface preparation and on the type of primer used. The good bond durability in saltwater exposure of anodized surface pretreated joints has been shown... 

TWO SEPARATE ALTERED or damaged layers classically have been recognized on metal surfaces formed by cutting- or polishing-type processes namely, an amorphous-like "Beilby" layer and a plastically deformed layer. Modern work indicates that the Beiiby layer is not, in fact, formed by the common important methods of surface preparation but that a deformed layer always is. The detailed structure of this layer is reviewed. Some consideration is also given to residual elastic stresses, surface topography, and embedded abrasive. 

It is apparent both from published micrographs and from the method of surface preparation that the surfaces of Otter s crystals were faceted or terraced. This condition could possibly account for the differences observed. The twinning in the oxide on the 110 and 113 faces was apparently taking place on ill planes of the oxide and was not related specifically to the metal surface. This twinning was not always present and its occurrence bears further investigation. 

The importance of chloride ions for SERS was realized in the very first studies. In fact, Jeanmaire and Van Duyne have studied the dependence on chloride concentration and found that optimal signals were obtained for a halide/pyridine concentration ratio of about 2. This is dependent on the method of surface preparation. The role of chloride ions in the ORC, essentially in facilitating the formation of insoluble silver chloride in the oxidation stage, was already discussed in Section II.2(ii). 

Use ultra-high vacuum methods of surface preparation and surface analyses to form tailored surfaces. Synthesize nanoclusters to have the tailored surface. 

A brief enumeration of the relevant UHV characterization techniques follows this introduction. Methods of surface preparation are next considered, after which progress in the determination of the structure and composition of stable surface phases of p and 6H crystals is reviewed. The final section describes work on the SiC interface with 15 different metals, both as-prepared and after thermal annealing. 

Unlike corrosion with water, the method of surface preparation dramatically alters Ae Table I provides representative data for the voltammetry of Cp e. More reversible electrochemistry (i.e., smaller AE values) is obtained with electrodes with freshly cleaved surfaces relative to those resurfaced by sanding. Further differences in were noted for electrodes sanded inside and outside a glove b<)x (not included in Table I). Cleaving electrodes... 

In most metal-semiconductor contacts, the semiconductor surface before metal deposition is prepared by chemical cleaning and a thin insulating oxide layer is invariably left on the surface of the semiconductor. The thickness of this interfacial layer depends on the method of surface preparation and, for a good Schottky contact, must be less than about 20A. The energy-band diagram of a contact with an interfacial oxide layer is... 

Flame and corona, although useful in oxidizing the surfaces of plastics, have limited utility in many applications. In addition, the transitory nature of these modifications prevents their widespread use in many applications. Corona treatment is limited to both the materials that are responsive to this method of surface preparation and the part configuration itself. Complex shapes cannot easily be treated, as the treatment quality is a function of the distance of the part from the electrode. Thus small-diameter holes and... 

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