Performance and material selection

Table 2. Summary of Criteria for Material Selection and Performance Evaluation ...

Corrosion damage from molten salts can occur in a wide variety of materials and by different mechanisms. It has been pointed out that although many studies have been performed, quantitative data for materials selection and performance prediction are rarely available [15]. Molten salt corrosion is usually applicable to materials retaining the molten salt, as used in heat treating, solar and nuclear energy systems, batteries, fuel cells, and extractive metallurgical processes. Some factors that can make molten salts extremely corrosive include the following ... 

The starting point is generally that of material selection and performance and the end point that of the consideration of structural safety (if relevant). A second aspect concerns the combustion products and what risk these pose to occupancy of a building or enclosed space like a ship, aircraft or motor vehicle. 

Important trends that are driving the E E industry, which are influencing materials selection and performance include ... 

Pumps, compressors, turbines, drivers, and auxiliary machinery should be designed to provide reliable, rugged performance. Pump selection and performance depend on the capacity required and tlie nature of Uie fluids involved. Remotely controlled power switches and shutoff valves are necessary to control fluid flow during an emergency. The inlets for air compressors should be strategically located to prevent the intake of hazardous materials. 

The technology of manufacturing the same basic type or grade of plastics (as with steel and other materials) by different suppliers may not provide the same results. In fact a supplier furnishing their material under an initial batch number could differ when the next batch is delivered and in turn could effect the performance of your product. Taking into account manufacturing tolerances of the plastic, plus variables of equipment and procedure, it becomes apparent that checking several types of materials from the same or from different sources is an important part of material selection and in turn their use. 

Establishing design controls entails examining current design features, component specifications, and necessary information to ensure that the potential cause can be avoided, or at least detected if it occurs. These controls then become inputs into making a Control Plan (Technique 55). Controls in the razor example include specifications for incoming parts or materials, material selection, and an understanding of the impact of component variation on performance. 

This third edition is essentially an entirely new book. Our goal has been to describe the materials, principles and methods of ion chromatography in a clear, concise style. Whenever possible the consequences of varying experimental conditions have been considered. For example, the effects of the polymer structure and the chemical structure of ion-exchange groups and the physical form of the ion-exchange group attachment on resin selectivity and performance are discussed in Chapter 3. 

There are no standard test methods specific for discontinuous fiber (or short fiber) reinforced thermoplastics. It is also not clear whether a geometry-independent fracture parameter can be measured for these nonuniformly inhomogeneous materials. However in spite of these reservations there has been considerable work conducted towards characterizing short fiber composites for fracture toughness using the standard and other procedures outlined in the previous sections. The investigators have recognized that fracture mechanics data provide much more reliable information than the customary alternative tests for material selection and also a service performance indicator for components. 

Faessler, K., Spaehn, H., Sped, L. 1989. Corrosion under oil and gas well conditions at extremely high hydrogen sulfide contents. Materials selection and operating performance. Werkstoffe und Korrosion 40 (2), pp. 71-89. 

Methods to evaluate materials performance are used both for materials selection and for failure analysis. Materials selection cein be based on field surveys, exposure tests in commercial units, or laboratory test results [27]. Field surveys represent long-term results from actual test environments, but the environmental conditions usually are not well-defined or constant. Exposure tests in commercial units may or may not be realistic, depending upon the test method approach. This point is discussed in the next section. Laboratory tests with simulated flue gas run the risk of missing the effects of trace constituents, which typically are not present in simulated environments. Laboratory tests with selected trace elements may not be indicative of the effect of these elements on materials performance in the field. 

This chapter has covered some of the stress loading situations other than simple tensile, compressive and bending loads encountered by plastics parts. The unique characteristics of plastic materials of certain types make them especially suited to resist the specific stress conditions. With proper part design, material selection and modification the designer can make parts that will perform well under unique stress conditions. 

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