Conditioning of the specimen

As practiced by the UL, the procedure for selecting an RTI from Arrhenius plots usually involves making comparisons to a control standard material and other such steps to correct for random variations, oven temperature variations, condition of the specimens, and others. The stress-strain and impact and electrical properties frequently do not degrade at the same rate, each having their own separate RTIs. Also, since thicker specimens usually take longer to fail, each thickness will require a separate RTI. 

Some isotherms of water vapours sorption-desorption are presented in Fig, 1. In the first cycle of sorption, the isotherms have a pronounced stepwise character, and the values of water vapour sorption are unusually low for wood specimens. This is connected with the strict drying conditions of the specimens 378K at a rapid rise in temperature) after the exposure procedure, which resulted in the fixation of the nonequilibrium structure. After saturation with water vapours and the subsequent vacuum treatment at 295K during the procedure of the sorption experiment, the second cycle of isotherms was carried out, and this state was regarded as an equilibrium one. Thus, the analysis of the specimens structure was performed on the basis of the sorption-desorption isotherms of the second cycle. 

The powder diffraction experiment is the cornerstone of a truly basic materials characterization technique - diffraction analysis - and it has been used for many decades with exceptional success to provide accurate information about the structure of materials. Although powder data usually lack the three-dimensionality of a diffraction image, the fundamental nature of the method is easily appreciated from the fact that each powder diffraction pattern represents a one-dimensional snapshot of the three-dimensional reciprocal lattice of a crystal. The quality of the powder diffraction pattern is usually limited by the nature and the energy of the available radiation, by the resolution of the instrument, and by the physical and chemical conditions of the specimen. Since many materials can only be prepared in a polycrystalline form, the powder diffraction experiment becomes the only realistic option for a reliable determination of the crystal structure of such materials. 

Note the condition of the specimen uncontaminated, bloody, meconium stained, xanthochromic, or obviously contaminated with mucus. Blood and meconium interfere with most tests. The report of the result should always list any contaminates seen. 

The effect of thermal vibration also illustrates what has been called the approximate law of conservation of diffracted energy. This law states that the total energy diffracted by a particular specimen under particular experimental conditions is roughly constant. Therefore, anything done to alter the physical condition of the specimen does not alter the total amount of diffracted energy but... 

Unless the actual condition of the specimen had been recorded in advance of the test, it would be difficult to decide subsequently whether any defect was caused by the test. 

In general, the orientation of cracks will depend on the processing conditions of the specimens or components furthermore, their distribution may be random, or there may be some preferred orientation. Although, until now, it has been assumed that cracks are perpendicularly oriented to a uniaxial tensile stress field, this assumption is not generally necessary and has only been made to simplify the above arguments. 

In many research and regulatory cases, data descriptive of a specimen must be associated or coordinated with the descriptions of the strains isolated from the specimens. Some common specimen data are exemplified by "total" microbial population, numbers of special groups of organisms such as coliforms, heat resistant bacteria, halophiles, psychrophiles, etc., the presence or absence of certain organisms (e.g.. Salmonella), incubation media, incubation conditions, geographic location of the specimen, physical and chemical condition of the specimen at the time of accession, and conditions of isolation of microbial strains from the specimen. 

The tensile test results depend on the test atmosphere, i.e. temperature and moisture conditions, test speed, and type and conditioning of the specimen used. According to the standard, the test atmosphere can be... 

The overlapping of curves for final stages of the separation event validates the existence of a universal strain-softening behavior (exponent), independent of the initial condition of the specimen. This observation can be corroborated by a loading-reloading static PFT test on the same specimen. 

Fig. 1 shows the geometric dimensions of the specimen. The heat treatment conditions of the specimen is 830°C(vacuum) holding 15 minutes and 25 minutes for austenitisation, and then make it in the salt bath furnace immediately for tempering which the salt bath conditions were placed on each constant temperature of 290 °C, 310 C and 330 C for 30 minutes, 60 minutes and 120 minutes, then quench in the water. Each austempering conditions are coded by the salt bath conditions, such as 290°C-30m. 

The fracture is predominantly intergranular. The elongated p-grains have a hexagonal shape with a length - 5 to lOpm and aspect ratios of - 5 to 10. In Figure 5 a heat treated (1400°C, lOh + 1300°C, lOh) specimen s fracture surface is presented. Although the experimental conditions of the specimen... 

The authenticity of the data given in the tables has been determined mainly by the reliability of the methods used in obtaining the numerical values of the property and the purity and condition of the specimens, and also from statistical indications. The number of reliable data may not therefore always include the most recent in a number of cases, preference may have been given to results obtained some decades ago and not to recent, sometimes incidental values, found for specimens of indefinite phase composition. To diminish the well-known subjective character of such an estimate in the determination of the reliability of certain data, use was made of the previously ascertained regularity of their variations, associated for example with the atomic number of the elements, electronegativity values, and acceptor capacity of the atom cores, and also of the actual experience acquired by the author and the group of workers in the laboratory under his direction. 

The thermal conductivity values have been obtained principally by the steady-state method most of the data have been converted by the authors of the different publications, including the author of the present reference work, to nonporous condition of the specimens, using the fairly reliable extrapolation to zero porosity accordingto Kingery s formula xp yp(l-P), where P is the porosity in fractions of unity [239], However, despite the absence in a number of publications of any reference to the condition of the specimens and their porosity, the author has considered it possible to reproduce the thermal conductivity data given in these publications as tentative values, since information on the thermal conductivity of refractory compounds is extremely scanty. 

Dielectric strength is defined as the potential per unit of thickness that will cause catastrophic failure of a dielectric material. This value is measured according to ASTM DI49. The value is dependent on the method of application of potential the nature of the potential dc or frequency of ac, and the temperature, and it varies with the conditioning of the specimen, all of which must be specified with the value. 

For wear resistance of decorated plastics, results are normally interpreted by a subjective assessment of the appearance or condition of the specimen after a fixed number of abrasion test cycles. For repeatable results, a standardized grading system (e.g. a 1 - 5 visual scale) should be used to measure the change in appearance and rank performance. Reference photographs along with an associated verbal... 

---