Fabrication process system

Michaeis A S 1960 Rheoiogicai properties of aqueous ciay systems Ceramic Fabrication Processes ed W D Kingery (New York Wiiey) pp 23-31... 

Nonwoven technologies that employ machinery and processing principles traditionally used to manufacture textile, paper, or extmded materials, when viewed collectively, form what may be termed the primary or basic nonwoven fabric manufacturing systems. These systems are or can be continuous processes. Common to each of these systems are four sequential phases fiber selection and preparation, web formation, bonding, and finishing. 

Catalyst Selection. The low resin viscosity and ambient temperature cure systems developed from peroxides have faciUtated the expansion of polyester resins on a commercial scale, using relatively simple fabrication techniques in open molds at ambient temperatures. The dominant catalyst systems used for ambient fabrication processes are based on metal (redox) promoters used in combination with hydroperoxides and peroxides commonly found in commercial MEKP and related perketones (13). Promoters such as styrene-soluble cobalt octoate undergo controlled reduction—oxidation (redox) reactions with MEKP that generate peroxy free radicals to initiate a controlled cross-linking reaction. 

Some fabrication processes, such as continuous panel processes, are mn at elevated temperatures to improve productivity. Dual-catalyst systems are commonly used to initiate a controlled rapid gel and then a fast cure to complete the cross-linking reaction. Cumene hydroperoxide initiated at 50°C with benzyl trimethyl ammonium hydroxide and copper naphthenate in combination with tert-huty octoate are preferred for panel products. Other heat-initiated catalysts, such as lauroyl peroxide and tert-huty perbenzoate, are optional systems. Eor higher temperature mol ding processes such as pultmsion or matched metal die mol ding at temperatures of 150°C, dual-catalyst systems are usually employed based on /-butyl perbenzoate and 2,5-dimethyl-2,5-di-2-ethyIhexanoylperoxy-hexane (Table 6). 

Applications. Epoxy resias constitute over 90% of the matrix resia material used ia advanced composites. In addition, epoxy resias are used ia all the various fabrication processes that convert resias and reinforcements iato composite articles. Liquid resias ia combiaation, mainly, with amines and anhydride are used for filament winding, resia transfer mol ding, and pultmsion. Parts for aircraft, rocket cases, pipes, rods, tennis rackets, ski poles, golf club shafts, and fishing poles are made by one of these processes with an epoxy resia system. 

Procedures for assurance of quality in the design, fabrication, installation, maintenance, testing and inspection for critical equipment are ) red. Safety requires that critical safety devices must operate as i led and process system components must be maintained to be able to contain design pressures. 

Continuously rated filters have whole sections of the filter shut off from the airflow and then those sections are shaken or cleaned. Shaking is carried out in sequence, usually by electric motor. Where the filter is cleaned it is done by a jet of compressed air being blown in reverse to the airflow through the fabric. This system does not require whole sections to be shut down, as the reverse blow is carried out when the filter is on-stream. The time of blow is very small and is measured in parts of a second rather than in minutes, as in the case of shaking filters. The application of these filters is in continuous processes and where the dust burdens are high (in excess of 100 g/m ). 

Based on the micro-electronics fabrication process, Micro-Opto-Electro-Mechanical Systems (MOEMS) have not yet been used in astronomical instrumentation, but this technology will provide the key to small, low-cost, light, and scientifically efficient instruments, and allow impressive breakthroughs in tomorrow s observational astronomy. Two major applications of MOEMS are foreseen ... 

A variety of optical oxygen sensor systems have been developed for applications such as biomedical, environmental and process control . But very few of them have been critically assessed for their suitability for food packaging applications. It has been proven that substantial development, optimization and redesign of the oxygen-sensitive materials and fabrication processes are required for the oxygen sensors to match practical requirements for these applications5. In particular, specific requirements of food applications are ... 

Worm end products, 18 646 Worsted wool-processing system, 26 383-384, 385-386 Worsted yarn, 11 178 Wort, 3 563, 564, 574, 575, 583 separation, 3 578-579 Wound closure, suture size and, 24 216 Wound closure biomaterials, 24 205. See also Sutures Wound dressings cotton smart, 3 31 ethylene oxide polymers in, 10 687 hydrogels in, 13 751-752 Woven fabrics, 11 178 dyeing, 9 170-171 Woven flax fibers, 11 594 Woven plastic bags, 18 12 Wovens... 

FuelCell Energy is a partner with Versa Power Systems, Nexant, and Gas Technology Institute to develop more affordable fuel-cell-based technology that uses synthesis gas from a coal gasifier. The key objectives include the development of fuel cell technologies, fabrication processes, and manufacturing capabilities for solid oxide fuel cell stacks for multi-mega-watt power plants. 

A cross-sectional schematic of a monolithic gas sensor system featuring a microhotplate is shown in Fig. 2.2. Its fabrication relies on an industrial CMOS-process with subsequent micromachining steps. Diverse thin-film layers, which can be used for electrical insulation and passivation, are available in the CMOS-process. They are denoted dielectric layers and include several silicon-oxide layers such as the thermal field oxide, the contact oxide and the intermetal oxide as well as a silicon-nitride layer that serves as passivation. All these materials exhibit a characteristically low thermal conductivity, so that a membrane, which consists of only the dielectric layers, provides excellent thermal insulation between the bulk-silicon chip and a heated area. The heated area features a resistive heater, a temperature sensor, and the electrodes that contact the deposited sensitive metal oxide. An additional temperature sensor is integrated close to the circuitry on the bulk chip to monitor the overall chip temperature. The membrane is released by etching away the silicon underneath the dielectric layers. Depending on the micromachining procedure, it is possible to leave a silicon island underneath the heated area. Such an island can serve as a heat spreader and also mechanically stabihzes the membrane. The fabrication process will be explained in more detail in Chap 4. 

This chapter includes two different sensor system architectures for monolithic gas sensing systems. Section 5.1 describes a mixed-signal architecture. This is an improved version of the first analog implementation [81,91], which was used to develop a first sensor array (see Sect. 6.1). Based on the experience with these analog devices, a complete sensor system with advanced control, readout and interface circuit was devised. This system includes the circular microhotplate that has been described and characterized in Sect. 4.1. Additionally to the fabrication process, a prototype packaging concept was developed that will be presented in Sect. 5.1.6. A microhotplate with a Pt-temperature sensor requires a different system architecture as will be described in Sect. 5.2. A fully differential analog architecture will be presented, which enables operating temperatures up to 500 °C. 

VAC TRAX is a mobile system that uses existing process equipment and requires minimal custom-fabricated process equipment. This system is also flexible enough to perform over a range of variations of the processing parameters (e.g., concentration of contaminants). VAC TRAX is suitable for sites with small soil volumes (200 to 2000 m ). 

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