Cleaning surface

The meehanism of flame treatment is thermal oxidation of the polymer surfaee. Flame temperature may exceed 2000 °C. It can clean the surface and remove the weak boundary layer by vaporizing surface contamination and low-molecular-weight polymers. 

Chemical treatment, or etching, oxidizes the plastic surface similarly to corona treatment. For instance, chromic acid is used to etch the surface of polyethylene and polypropylene (PP). An increase in etching time and temperature intensifies the surfaee treatment by inereasing the degree and depth of oxidation. 

The reactivity of solids is sometimes reduced by the existence of unreactive (passivating) surface layers that are easily removed by mechanical energy. In this way the reactivity of hydrogenation catalysts such as nickel or platinum has been greatly increased. The use of metals and nonmetals in synthetic reactions under mechanical surface cleaning has been reviewed [50]. 

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Surface area Surface areas Surface catalysis Surface cleaning Surface coatings... 

Fluorotitanic acid is used as a metal surface cleaning agent, as a catalyst, and as an aluminum finishing solvent (see Metal surface treatments). Fluorotitanates are used in abrasive grinding wheels and for incorporating titanium into aluminum aHoys (see Abrasives Aluminumand aluminum alloys). 

Surface Modification. Plasma surface modification can include surface cleaning, surface activation, heat treatments, and plasma polymerization. Surface cleaning and surface activation are usually performed for enhanced joining of materials (see Metal SURFACE TREATMENTS). Plasma heat treatments are not, however, limited to high temperature equiUbrium plasmas on metals. Heat treatments of organic materials are also possible. Plasma polymerization crosses the boundaries between surface modification and materials production by producing materials often not available by any other method. In many cases these new materials can be appHed directly to a substrate, thus modifying the substrate in a novel way. 

In dipping generally, but particularly with the anode process, it is desirable to use tanks that circulate the coagulant and latex compound, particularly the latter. Use of circulation keeps the Hquid surface clean and free from lumps, scum, or bubbles. Mechanical circulation can cause mbber particle instabihty, however, and eventually coagulate the compound. Therefore, tanks should be designed to minimize friction or shear action, and the compound stabilized to maintain mechanical stabiUty. 

D. J. Mattox, Surface Cleaning in Thin-Film Technology, American Vacuum Society, New York, 1975. 

Blow the surface clean with air at brief intervals. 

To have a minimum tracking temperature (at which the grease may start conducting) of 200°C. Apply this grease swiftly after the surface cleaning to avoid a fresh oxidation. The following are a few types of greases ... 

Figure 6 Spectra of ceramic samples showing effects of surface cleaning on carbon content (1) spectrum of specimen before cleaning (2) spectrum of the same specimen after cieaning (3) and (4) are spectra of two other surface-cleaned specimens. ...

The following substances chloroform, carbon tetrachloride 1,1,2-trichloroethane, 1,1,2,2-tetratchloroethane 1,1,1,2-tetrachloroethane pentachloroethane, vinylidene chloride 1,1,1 -trichloroethane and any substance containing one or more of those substances in a concentration equal to or greater than 0.1% by mass, other than (a) medical products (b) cosmetic products Supply for use at work in diffusive applications such as in surface cleaning and the cleaning of fabrics except for the purposes of research and development or for the purpose of analysis... 

Surface cleaning/etches. As with aluminum and titanium, the most critical test for bonded steel joints is durability in hostile (i.e., humid) environments. The fact that the problem is a serious one for steel was illustrated in a study [117] that compared solvent cleaned (smooth) 1010 cold-rolled steel surfaces with FPL aluminum (microrough) substrates. Although the dry lap-shear strengths were not markedly different, stressed lap-shear joints of steel adherends that were exposed to a humid environment failed in less than 30 days, whereas the aluminum joints lasted for more than 3000 days. 

Surface cleaning as a preparation for coatings is discussed in Sections 11.1 and 11.2. It is important to control degreasing baths to prevent accumulation of water and formation of corrosive products which will contaminate the atmosphere as well as the objects being degreased. In the case of tri-chlorethylene, stabilisers are added to prevent formation of hydrochloric acid Exclusion of dust is beneficial, and may necessitate filtering the air or use of a temporary protective. 

Nature of the metal surface Clean, smooth, metal surfaces usually require a lower concentration of inhibitor for protection than do rough or dirty surfaces. Relative figures for minimum concentrations of benzoate, chromate and nitrite necessary to inhibit the corrosion of mild steel with various types of surface finish have been given in a recent laboratory studyThese results show that benzoate effectiveness is particularly susceptible to surface preparation. It is unwise, therefore, to apply results obtained in laboratory studies with one type of metal surface preparation to other surfaces in practical conditions. The presence of oil, grease or corrosion products on metal surfaces will also affect the concentration of inhibitor required with the... 

Higher rates of sludging also take place in the boiler vessel. In turn, this potential fouling problem requires additional maintenance time because more frequent internal surface cleaning, wash-down, and boiler vessel sludge removal usually is required. Carryover of contaminants into the steam also is more likely. 

NOTE Where free-caustic reserve programs are employed to reduce the risk of caustic gouging, it is vital to maintain boiler surfaces clean and free of sludge. This is especially so in high heat-flux boilers, irrespective of whether they are of FT design or WT design. 

Metal surface cleaning, by virtue of (limited) sequestration, dispersing, surface-acting, and detergent properties. 

Some basic BW treatment objectives include keeping boiler surfaces clean and corrosion-free to minimize fuel bills and managing variable quality FW smoothly and efficiently to limit upsets and other downstream problems. But the nature of potential boiler deposition problems changes with increases in pressure and, simply put, is primarily concerned with a reduction in simple, hardness-related deposits and an increase in complex, iron oxide deposits. The effect of dirty boilers on fuel costs can be seen in Figure 10.4. 

Additionally, the surfactant properties of filmers reduce the potential for stagnant, heat-transfer-resisting films, which typically develop in a filmwise condensation process, by promoting the formation of condensate drops (dropwise condensation process) that reach critical mass and fall away to leave a bare metal surface (see Figure 11.2). This function, together with the well-known scouring effect on unwanted deposits keeps internal surfaces clean and thus improves heat-transfer efficiencies (often by 5-10%). 

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