Coatings requirements

Epoxies provide excellent chemical, moisture, and abrasion resistance. However, because a solvent can sometimes dissolve the epoxy present in the laminate, rework on an epoxy coating requires heat or abrasion to remove the coating. 

Figure 11-9. Blade coating requirements and coating evolution.

Sample requirements STM—solid oonduaois and semiconductors, conduaive coating required for insulators SFM— solid conduaors, semiconductors and insulators... 

As with chemical etches, developing optimum conversion coatings requires assessment of the microstructure of the steel. Correlations have been found between the microstructure of the substrate material and the nature of the phosphate films formed. Aloru et al. demonstrated that the type of phosphate crystal formed varies with the orientation of the underlying steel crystal lattice [154]. Fig. 32 illustrates the different phosphate crystal morphologies that formed on two heat-treated surfaces. The fine flake structure formed on the tempered martensite surface promotes adhesion more effectively than the knobby protrusions formed on the cold-rolled steel. 

Many of the modern, high-performance coatings require a high degree of skill in application and are considerably less tolerant than older, conventional materials. Caution is required in choosing coatings when there is no record of sound work by contractors. 

The surface condition of the object to be coated requires specifying extremely carefully if a high standard of finish is required, because powder coating tends to faithfully reflect surface contours and blemishes. 

The differences between asphalt and coal tar in relation to their application as pipeline coatings require comment. 

Hot-applied coatings require special melting and handling equipment to be available at the construction site. Clearly, considerable economies are possible if this equipment can be dispensed with, particularly in remote areas... 

Covalent chemical attachment of an enzyme to an electrode or a polymer coating requires mild and specific chemistry to react with amino acids in the protein in aqueous... 

The effective development of blocked isocyanate based coatings requires a complete understanding of the cure chemistry. Many materials have been identified which will improve cure response. Often these are reported as deblocking catalysts even though no direct evidence exists to support this claim. Most of these materials are well known catalysts of the cure reaction between hydroxyl and isocyanate and may be improving cure response solely by catalyzing this reaction. Effective development of catalyst systems requires a better understanding of the effect of catalysts on cure. 

For formulated compounds small extruders need to be developed [10], while the application for coatings requires dedicated equipment [5]. 

If a biodegradable polymer does not exhibit satisfactory film-forming properties, it may also be used as a compression coat requiring a compaction process onto a drug-containing core [62-64]. 

Variations in ferritin protein coats coincide with variations in iron metabolism and gene expression, suggesting an Interdependence. Iron core formation from protein coats requires Fe(Il), at least experimentally, which follows a complex path of oxidation and hydrolytic polymerization the roles of the protein and the electron acceptor are only partly understood. It is known that mononuclear and small polynuclear Fe clusters bind to the protein early in core formation. However, variability in the stoichiometry of Fe/oxidant and the apparent sequestration and stabilization of Fe(II) in the protein for long periods of time indicate a complex microenvironment maintained by the protein coats. Full understanding of the relation of the protein to core formation, particularly at intermediate stages, requires a systematic analysis using defined or engineered protein coats. 

Poor nozzle access during coating Requires tallest expansion chamber... 

Based on the needs of certain application, the polymer should demonstrate versatile mechanical properties [e.g., stent coatings require polymers to be elastomeric and microsphere processing require them to have high glass transition temperature (7 )]. 

Table I. Comparison of the Amount of Coating Required to Apply a Coating of 0.01 mn onto Particles of Various Sizes...

Water Quality. Laboratory analysis of water salinity, hardness, and total suspended solids should be included to help prospective bidders select proper coalescing media, equipment metallurgy, and coating requirements. 

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