Casting surfaces

In preparation of permselective hoUow-fiber membranes, morphology must be controUed to obtain desired mechanical and transport properties. Fiber fabrication is performed without a casting surface. Therefore, in the moving, unsupported thread line, the nascent hoUow-fiber membrane must estabUsh mechanical integrity in a very short time. 

An ahoy of titanium containing 40—50% Ti and 45—50% Si is used as an additive in cast iron to shorten the graphite flakes. The effect is to provide a smooth casting surface. The resulting casting is then used to produce glass botde molds. 

As with the modified S S membrane, the L-S membrane was found to be asymmetric. The side of the membrane away from the casting surface had to be in contact with the feed brine during se rvi ce,... 

Foundry Activities (Casting) Surface Surface Treatment Process Chemical Coaling... 

Amount ot water vaporized from casting surface, g cm"2... 

In some cases, it helps to either polish or etch the surface of a solid sample — unless correlation between surface topography and composition is important. Small samples such as pins or crystals can be embedded in an epoxy cast and analysed either directly or after polishing the cast surface. Otherwise, small samples can simply be stuck into a piece of putty or onto tape or an adhesive pad. Because the sample cell is not evacuated, outgassing of the support material is not a problem with this approach. 

Uralite. [Hexcel] Polyurethanes for das-tomeis, casting, surface coatings, adhesives. 

Casting Surfaces A casting such as a fitting serves as a substrate for coating and must be smooth and free of oil and rust. Sandblasting is effective for surface preparation. 

The gum Arabica biopolymer must be examined microscopically for verifying its morphology and microstructure. Figure 12.2a and 12.2b shows the SEM photograph of the caste surface of the biopolymers on smooth and scratched substrate respectively. The latter surface was a textured one with grown anisotropy due to cast over scratched substrate. It was taken at a magnification of 10,000, and indicates a domain like microstructure, which is precursor of a growing anisotropy in the specimen [21]. 

SBS. The diffusion coefficient of cyclohexane at 20°C in an SBS block copolymer was measured as a function of film thickness and casting surface. Films of SBS TR-41-2443 (Shell Chemical Co., Houston, TX) were cast under identical conditions from benzene onto glass. Teflon, or previously cleaned mercury surfaces. The films were allowed to dry for a day by evaporation within a partial benzene atmosphere. The films were dried further in a vacuum dessicator for two days before being used in a sorption experiment. The properties of the copolymer are described in Table I. 

Figure 3 shows the approach to equilibrium of D against film thickness for different casting surfaces and film pretreatments. It can be seen that the approach to equilibrium of the diffusion coefficient is quicker in the intermediate thickness range for the mercury cast films and... 

The equilibrium diffusion coefficient De for glass and Teflon cast films is identical with that of mercury cast and annealed films. This, in fact, should be expected since after stress is relieved from glass and Teflon cast films upon absorption, the polymer molecules return to their normal orientation as in the mercury cast and annealed films. Therefore, the equilibrium diffusion coefficient is the same regardless of the casting surface. 

Surface finish of the test coupon Various manufacturing processes can change the physical form of the metal s initial surface or produce surface films, either of which may influence the eharacteristies of the corrosion deposit that is developed when in contact with water. These effeets may influence or change the mechanism controlling the level of eontamination. The standard sit-and-soak test defines a machined smface that will not be representative of a cast surface, for example. In the first set of eonormative tests, aetual galvanized steel pipe was used to overcome precisely this sort of problem. 

This is an example of the use of an amorphous silica-sodium silicate composition of Si02/Na20 ratio 5 1 as a binder for foundry sand cores, a polyvinyl acetate aqueous dispersion as a co-binder and additive for durability, and pitch as an aid to improve shake-out and casting surface finish. 

The polymer concentration in the solution is adjusted depending on the viscosity. Higher solution viscosities are required for the production of hollow-liber membranes, as compared to flat sheet production, because the fiber fabrication is performed without a casting surface. 

Coal dust is usually added to green sand for cast iron moulding. It is used to a limited extent in some non-ferrous foundries. Coal dust may be mixed with small amounts of resins and oil products. During casting, the thermal degradation produces lustrous carbon , which improves the casting surface finish and shake-out properties. Coal dust is added for three reasons ... 

When die-cast lettering, numerals, trade marks, diagrams or instructions are required, they should be designed as raised from the casting surface. This reduces die cost, as it is easier to cut the design into the die surface than to make a raised design on the die surface. 

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