Spray casting

Spray Deposition Net or Near-Net Shape Manufacturing - Spray Forming - Spray Casting - Spray Rolling... 

In polymer systems, the combination of properties of different components is achieved in a multitude of ways. For example, polymer layers of different functionalities are applied on a polymer substrate by spraying, casting, dip coating, or spreading with a doctor blade. Polymer coatings can be combined with layers of nonpolymeric materials applied from solutions or suspensions of the coating material or precursors thereof, or deposited via vapor phase using physical and chemical vapor deposition. 

FIGURE 20.13 Three-dimensional spectroelectrochemical series for a spray-cast film of PProDOT-Hx2- (From Reeves, B., Macromolecules, 37, 7559, 2004. With permission.)... 

Figure 8.12 (a) AFM morphology and roughness data for a spray cast and thermally cured wax-polymer film. The image is a square 10 pm x 10 pm in size, (b) All contact angle data. The uncertainty in contact angle measurements on polymeric films was approximately +4 and in flame treated superhydrophohic surfaces was 3°. Filled circles correspond to polymer and unfilled triangles correspond to wax-polymer films for both as deposited and flame treated cases. With permission from [11]. 

Tang et al. [39] prepared superomniphobic coatings by spray-casting dispersions of polyurethane and MoS nanoparticles. After the spraying... 

Figure 10.10 Scanning electron microscope images (a) and (b), showing morphology of cellulose nitrate biopolymer spray cast from cellulose nitrate/solvent/biolubricant ternary system (c) measured static water contact angle and hysteresis on the biopolymer coating as a function of biolubricant/solvent weight ratio [18].

The preparation of electrochromic, solvent-processable, thiophene-based polymers allowed electrode modification (e.g., upon spray casting) [539-541]. At the same time, the color of the film could be switched electrochemicaUy. In addition, special derivatives of polyaniUne [542] showed a multielectrochromic behavior (Fig. 48) [543, 544]. 

Figure 3 Picture of the inspected part (plasma-sprayed chromium cast iron on ferritic steel). The surface presents several cracks I to 15 pm wide.

Fire-Resistant Hydraulic Fluids. Fire-resistant hydrauhc fluids are used where the fluid could spray or drip from a break or leak onto a source of ignition, eg, a pot of molten metal or a gas flame (17). Conditions such as these exist in die-casting machines or in presses located near furnaces. Specific tests for fire resistance are conducted by Factory Mutual in the United States. 

Quenching. After solution treatment, the product is generally cooled to room temperature at such a rate to retain essentially all of the solute in solution. The central portions of thicker products caimot be cooled at a sufficient rate to prevent extensive precipitation in some alloys. Moreover, some forgings and castings are dehberately cooled slowly to minimize distortion and residual stress produced by differential cooling in different portions of the products. Cold water, either by immersion or by sprays, is the most commonly used cooling medium. Hot water or a solution of a polymer in cold water is used when the highest rates are not desired. Dilute Al—Mg—Si and Al—Mg—Zn extmsions can be effectively solution heat treated by the extmsion process therefore, they may be quenched at the extmsion press by either air or water. 

Certain casting molds are hardened by spraying with a solution of aluminum chloride before firing. 

The diversity of release products and the wide range of release problems make classification difficult. One approach is by product form, with subdivisions such as emulsions, films, powders, reactive or iaert sprays, reactive coatings, and so on. Another approach is by appHcation, eg, metal casting, mbber processiag, thermoplastic iajection mol ding, and food preparation and packagiag. 

Although the continuous casting of steel appears deceptively simple in principle, many difficulties are inherent to the process. When molten steel comes into contact with a water-cooled mold, a thin soHd skin forms on the wall (Eig. 10). However, because of the physical characteristics of steel, and because thermal contraction causes the skin to separate from the mold wall shortly after solidification, the rate of heat abstraction from the casting is low enough that molten steel persists within the interior of the section for some distance below the bottom of the mold. The thickness of the skin increases because the action of the water sprays as the casting moves downward and, eventually, the whole section solidifies. 

The Hquid monomers are suitable for bulk polymerization processes. The reaction can be conducted in a mold (casting, reaction injection mol ding), continuously on a conveyor (block and panel foam production), or in an extmder (thermoplastic polyurethane elastomers and engineering thermoplastics). Also, spraying of the monomers onto the surface of suitable substrates provides insulation barriers or cross-linked coatings. 

After leaving the casting machine, the slab is cooled by water sprays to 180—240°C and fed into the mill, which is generally of the four-high roU type, where a 60% reduction is taken in one pass. The strip is then coiled and, when the casting mn has been completed, is fed back through the mill and roUed at a temperature of 80—90°C, with a reduction up to 50%, to give the required final thickness, finish, and properties. 

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