Structural materials, tests

Structural material tests in air, in sodium, in water/steam, and under post-irradiation condition have been conducted to revise the Monju Material Strength Standard and to prepare a new version for DFBR. 

A comprehensive literature review on the degradation of mechanical properties of structural materials exposed to liquid Pb and Pb-Bi is given in Ref. [16]. As reported in this reference most of the experiments have been performed in liquid Pb-Bi and the extension of these experimental findings to pure Pb cordd lead to incorrect estimations, since liquid Pb-Bi seems to be more aggressive than liquid Pb. Moreover, the main structural materials tested were the 9Cr ferritic/martensitic steel 791 and the austenitic steel AISI316. However, a generalization of the residts obtained in order to predict the behavior of other 9Cr ferritic/martensitic and austenitic steels is not feasible, since as, for instance, minor alloying elements in the steel impact the materials behavior in these liquid metals. 

The AET was used at standard tests of numerous structural materials, above all steels and cast iron, prepared are ceramic samples. Part of tested samples had qjecial sur ce layer treatments by laser, plasma nitridation and similar. Effect of special surface treatment the authors published already earlier [5,6]. In this contribution are summed up typical courses of basic dependencies, measured by the AET at contact loading. 

The effect of impurities in either structural material or corrosive material is so marked (while at the same time it may be either accelerating or decelerating) that for rehable results the actual materials which it is proposed to use should be tested and not types of these materials. In other words, it is much more desirable to test the actual plant solution and the actual metal or nonmetal than to rely upon a duphcation of either. Since as little as 0.01 percent of certain organic compounds will reduce the rate of solution of steel in sulfuric acid 99.5 percent and 0.05 percent bismuth in lead will increase the rate of corrosion over 1000 percent under certain conditions, it can be seen how difficult it would be to attempt to duplicate here all the significant constituents. 

All ordinary ferrous structural materials, mild steels, low-alloy steels and wrought irons corrode at virtually the same rate when totally immersed in natural waters. Wrought iron may be slightly more resistant than mild steel in a test in sea-water at Gosport, Scottish wrought-iron specimens lost about 15% less weight after 12 months immersion than specimens of ordinary mild steel. As shown in Table 3.5, the process of manufacture and the composition of mild steel do not affect its corrosion rate appreciably . 

A similar result was found by Burdekin and Stave. For this test to be valid, the material tested must be of the same thickness as the structure being analysed. This is due to the effect of material thickness on the toughness versus temperature characteristics (Fig. 8.85). 

A central problem in complex materials systems of any kind involves testing to deteet flaws, analysis to predict their effect on remaining service life of the system, and repair strategies to overcome them. For the structural materials discussed in this chapter, these problems are uneharted territory in need of exploration by chemical engineers. 

Clearly, aerospace has been a major driver for advanced structural materials. It will continue to be a driver, although perhaps at a slower pace, particularly for weight reduction and higher temperature reliability. The slowdown of military aircraft development presents a unique problem because many of these programs, such as the advanced tactical fighter (ATF), were test beds for advanced-performance materials for which... 

Space technology development has also provided advanced-performance materials test beds in both communications and structural areas. The value of these programs has been passed on in many cases from space and the military to civilian aircraft. Many of the advanced-performance materials in the new generation of airline transports, such as structural composites, were first developed for spacecraft or advanced military aircraft. 

Since it was proposed in the early 1980s [6, 7], spin-relaxation has been extensively used to determine the surface-to-volume ratio of porous materials [8-10]. Pore structure has been probed by the effect on the diffusion coefficient [11, 12] and the diffusion propagator [13,14], Self-diffusion coefficient measurements as a function of diffusion time provide surface-to-volume ratio information for the early times, and tortuosity for the long times. Recent techniques of two-dimensional NMR of relaxation and diffusion [15-21] have proven particularly interesting for several applications. The development of portable NMR sensors (e.g., NMR logging devices [22] and NMR-MOUSE [23]) and novel concepts for ex situ NMR [24, 25] demonstrate the potential to extend the NMR technology to a broad application of field material testing. 

Except for a lew thermoset materials, most plastics soften at some temperatures, At the softening or heat distortion temperature, plastics become easily deformahle and tend to lose their shape and deform quickly under a Load. Above the heat distortion temperature, rigid amorphous plastics become useless as structural materials. Thus the heat distortion test, which defines The approximate upper temperature at which the material can be Safely used, is an important test (4,5.7.24). As expected, lor amorphous materials the heat distortion temperature is closely related to the glass transition temperature, hut tor highly crystalline polymers the heat distortion temperature is generally considerably higher than the glass transition temperature. Fillers also often raise the heat distortion test well above... 

In view of catalytic potential applications, there is a need for a convenient means of characterization of the porosity of new catalyst materials in order to quickly target the potential industrial catalytic applications of the studied catalysts. The use of model test reactions is a characterization tool of first choice, since this method has been very successful with zeolites where it precisely reflects shape-selectivity effects imposed by the porous structure of tested materials. Adsorption of probe molecules is another attractive approach. Both types of approaches will be presented in this work. The methodology developed in this work on zeolites Beta, USY and silica-alumina may be appropriate for determination of accessible mesoporosity in other types of dealuminated zeolites as well as in hierarchical materials presenting combinations of various types of pores. 

Because sulfuric acid and halogen are very corrosive, selection of the structural materials is an important issue. Screening tests have been carried out using test pieces of commercially available materials at GA [29], JAEA [30,31], etc. As for the gas-phase environment of the H2S04 decomposition step, some refractory alloys that have been used in conventional chemical plants showed good corrosion resistance. Figure 4.13 shows one of the experimental results of Alloys 800 and —600 obtained under gas-phase sulfuric acid decomposition environments at 850°C. Gas compositions in the upstream and downstream... 

Kubo, S. et al., Corrosion test on structural materials for iodine-sulfur thermochemical water splitting cycle, in Proc. 2nd Topical Conf. on Fuel Cell Tech., AIChE 2003 Spring National Meeting, New Orleans, March 30-April 3, 2003. 

Thus the effects of the rate of application of stress and the ambient temperature must be recognized when polymers are used as structural materials, and definite rates and temperatures must be specified for tests, such as those for tensile and flexural strengths cited in Chapter 3. A knowledge of the structure of polymers is essential for the understanding of these effects, which differ from the effects of stress and temperature on all other materials of construction. 

The last term in equation 5.245 represents the dilution of active component /, by the expansion of the biomass. Esener et al.m also present a two-compartment model which takes this effect into account and they emphasise the need to devise the theory so that it can be tested by experiment. In their model they identify a K compartment of the biomass which comprised the RNA and other small cellular molecules. The other compartment contained the larger genetic material, enzymes, and structural material. The model assumes that the substrate is absorbed by the cell to produce, in the first instance, K material, and thence it is transformed into G material. Additionally, the G material can be reconverted to K material, a feature intended to account for the maintenance requirement of the micro-organism. A series of material balances for the cellular components during growth in a CSTF produced the following differential equations ... 

Biomedical Applications. In the area of biomedical polymers and materials, two types of applications have been envisioned and explored. The first is the use of polyphosphazenes as bioinert materials for implantation in the body either as housing for medical devices or as structural materials for heart valves, artificial blood vessels, and catheters. A number of fluoroalkoxy-, aryloxy-, and arylamino-substituted polyphosphazenes have been tested by actual implantation in rats and found to generate litde tissue response (18). 

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