Microstructured fabrication techniques

Howard, R. E. Prober, D. E., "Nanometer-Scale Fabrication Techniques" in "VLSI Electronics-Microstructure Science", Vol. 5, Ein-spruch, N. G., ed., 1982. 

The steps in the selection and use of suitable microstructured devices for a particular chemical production are depicted in Figure 1.5. Majority of steps corresponds to the procedure that is followed for conventional equipments. However, more emphasis is placed on fabrication techniques as it involves structures in micro-, nanometer scale requiring very precise fabrication techniques. In addition, they should be able to accommodate, either individually or combined, these structures and sensors that are required to control the process. 

A whole set of parameters listed in Table 1 has to be considered for every kind of application and there is no easy decision for a specific catalyst integration technique. For decision making, the issues which have to be considered can be divided into three sets of categories, a) the reaction engineering, i.e. the catalyst and reaction dependent, b) the materials linked with preparation methods and c) the implications from microstructure fabrication and process. 

The choice of materials for microstructured fuel processors is mainly determined by the operating temperature and pressure. Because fuel processors are future mass products, only cheap fabrication techniques can be considered in the longer term. Hence only techniques suited for future mass production of microstructured fuel processors are briefly discussed below other techniques have been discussed in detail in other books [86, 87]. 

Laser ablation is a frequently apphed fabrication technique of proven industrial suitabihty [41, 42]. However, fabrication of microchaimels of several hundred micrometers depth, as typically required for many apphcations using microstructured reactors, will take too long and therefore the method is not cost competitive. For smaller chaimel dimensions, laser ablation is a viable option, especially for apphcations on the smaUer scale. 

One or more types of corrosion can cause condenser tube failures in seawater service. These corrosion types include turbulence/velocity stimulated corrosion at inlet ends or at partial tube blockages, galvanic-induced corrosion caused by a mismatch between tube and tubesheet/waterbox alloys, and selective corrosion attack caused by microstructural differences resulting from improper welding or fabrication techniques. 

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