Fabrication processes methods

Processing. SAN copolymers may be processed using the conventional fabrication methods of extmsion, blow mol ding, injection molding, thermoforming, and casting. Small amounts of additives, such as antioxidants, lubricants, and colorants, may also be used. Typical temperature profiles for injection mol ding and extmsion of predried SAN resins are as follows (101). 

Ceramics. The properties of ferroelectrics, basically deterrnined by composition, are also affected by the microstmcture of the densifted body which depends on the fabrication method and condition. The ferroelectric ceramic process is comprised of the following steps (10,24,25) (/) selection of raw oxide materials, (2) preparation of a powder composition, (J) shaping, (4) densification, and (5) finishing. 

Although all of the preceding processes can produce a p—n homojunction, the properties required from the junction and the fabrication costs determine the fabrication method. Methods of making other kinds of junctions are similar to those used to make homojunctions, but the materials on either side of such junctions are dissimilar. 

The production of vitreous siUca from chemical precursors was first described in patents filed in 1934, including a fabrication method in which fine, high purity powders were produced by decomposing silanes (39). Forms were then cast from aqueous sHps. More importantiy, a dame hydrolysis process which used SiCl as the chemical precursor was described (40). This latter approach led to a marked improvement in glass purity and served as the basis for the processes used in the 1990s to make synthetic vitreous siUca. 

Cost and Quality. Many factors affect catalyst support cost including which raw materials are used, the purity of the raw materials, the chemical processing steps required, the fabrication method used, the severity of calcination conditions, and the extent of the quaHty assurance procedure. In... 

Ease of cure, easy removal of parts from mold surfaces, and wide availabiHty have made polyesters the first choice for many fiber-reinforced composite molders. Sheet mol ding compound, filament winding, hand lay-up, spray up, and pultmsion are all weU adapted to the use of polyesters. Choosing the best polyester resin and processing technique is often a challenge. The polyester must be a type that is weU adapted to the processing method and must have the final mechanical properties requked by the part appHcation. Table 1 Hsts the deskable properties for a number of fiber-reinforced composite fabrication methods. 

Another important aspect of the fatigue of all materials is the statistical nature of the failure process and the scatter which this can cause in the results. In a particular sample of plastic there is a random distribution of microcracks, internal flaws and localised residual stresses. These defects may arise due to structural imperfections (for example, molecular weight variations) or as a result of the fabrication method used for the material. There is no doubt that failure... 

Generally the lower the process pressure, the larger the product that can be produced. With most labor-intensive fabricating methods, such as RP hand lay-up with TS plastic, relatively slow process curing reaction time of the plastic can be used so that there is virtually no limit on size (Fig. 8-63). 

The micro reactor properties concern process control in the time domain and process refinement in the space domain [65]. As a result, uniform electrical fields are generated and efficiency is thought to be high. Furthermore, electrical potential and currents can be directly measured without needing transducer elements. The reactor fabrication methods for electrical connectors employ the same methods as used for microelectronics which have proven to satisfy mass-fabrication demands. 

The fabrication method generates functional elements via anisotropic etching of high-quality semiconductor wafers, referred to as mother wafers.13 17 25 The process begins with photolithographic definition of patterns... 

Once the structural support layers have been fabricated by extrusion or EPD for tubular cells or by tape casting or powder pressing for planar cells, the subsequent cell layers must be deposited to complete the cell. A wide variety of fabrication methods have been utilized for this purpose, with the choice of method or methods depending on the cell geometry (tubular or planar, and overall size) materials to be deposited and support layer material, both in terms of compatibility of the process with the layer to be deposited and with the previously deposited layers, and desired microstructure of the layer being deposited. In general, the methods can be classified into two very broad categories wet-ceramic techniques and direct-deposition techniques. 

Both wet-ceramic techniques and direct-deposition techniques require preparation of the feedstock, which can consist of dry powders, suspensions of powders in liquid, or solution precursors for the desired phases, such as nitrates of the cations from which the oxides are formed. Section 6.1.3 presented some processing methods utilized to prepare the powder precursors for use in SOFC fabrication. The component fabrication methods are presented here. An overview of the major wet-ceramic and direct-deposition techniques utilized to deposit the thinner fuel cell components onto the thicker structural support layer are presented below. 

Processing and Application. Polystyrene and the other thermoplastics would not have been able to enter on their triumphal march if the manufacturers of processing equipment had not been able to provide efficient fabrication methods. A decisive factor was that between 1950 and 1960 the injection molding machine with a screw preplasticizer was developed and extrusion through slit dies to give sheeting or film followed by thermoforming was evolved. 

Practical laser processing of materials involves a batch of procedures, each of which has its own requirements preparation of the initial material (with parameters customized for the intended fabrication method), its proper optical exposure, and post-processing aimed at developing or refining the exposed material (e.g., thermal annealing, chemical development, or etching). 

Processing. SAN copolymers may be processed using the conventional fabrication methods of extrusion, blow molding, injection molding, thermo forming, and casting. 

Numerous film fabrication methods are available, depending on the film material. Table 11.1 summarizes some of the fabrication methods. General comments on substrate preparation and the various fabrication processes are presented in the order listed in the table. Applications to specific systems are summarized according to the electrode material type, including metals, carbon, and semiconductors. Carbon is sometimes classified as a semimetal, with properties intermediate between metals and semiconductors. 

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