An investigation was conducted of the potential for detection of the contact stress distribution in tapered roller bearing components made of carburized steel. Various raceway stress distributions were created by control of the profile and alignment of the rolling surfaces. Determination of residual stress in the rolling direction and peak breadth were made using a multiple tilt sin2 ψ technique. The measurements were made at the surface and at depths below the surface. It was found that the distribution of residual stress and peak breadth perpendicular to the rolling direction in the layers below the surface of the inner race correlated highly with the imposed contact stress distribution. The correlation was less in the case of the outer race. The residual stress distribution measured on the surface of the inner race was observed to be inversely proportional to the contact stress distribution.

Ceramics are sometimes bonded to ductile metals in order to make up for their brittle behavior for industrial use. The residual stress will be induced in ceramics bonded to metals at high temeprature, and it has a strong influence on the strength of ceramic-metal joints. A silicon nitride plate was bonded to a carbon steel plate by brazing to a copper sheet sandwiched between the two materials. The residual stress distribution of the joint specimen was determined by x-ray diffraction using the Gaussian curve method. The measured residual stress distribution almost agreed with that calculated by the three-dimensional thermoelastoplastic stress analysis using FEM, but differed remarkably from that calculated by the two-dimensional stress analysis. This is because a stress concentration occurs at the ceramic-metal interface and the stress distributes three - dimensionally. The stress σx in the axial direction on the surface of the specimen takes maximum values at the center and the edge of the interface.

The 95% confidence linits of the x-ray elastic and stress constants of α-alumina were detemined from seven kinds of diffraction planes by the Gaussian curve method in order to investigate the diffraction plane dependence of the eonstants. No difference in the elastic constants larger than their 95% confidence intervals was observed for most diffraction planes. Also, the measured elastic constants for most planes were closer to the values calculated from the Voigt model than those from the Reuss model. Since the diffraction line of the (410) plane measured with cobalt Kα radiation by using an automated x-ray stress analyzer locates at the highest diffraction angle of 168.4, the use of this plane will allow the most accurate stress measurement. Also, the measured x-ray elastic constants for the (410) plane almost agreed with both values calculated from the Voigt and Reuss models. Therefore, the (410) plane is the most appropriate plane for x-ray stress measurement of alumina.

This paper reports and discusses the results of a computer modeling study on powder diffraction profile analysis for crystallite size and strain of polycrystalline materials. The results of this computer modeling show that if the spans of diffraction profiles in reciprocal space (1/d) are not carefully chosen, an overestimation on size and an underestimation on strain may result in analysis by both the Warren-Averbach and the Hall-Williamson methods. A general way to eliminate such errors based on profile fitting and regeneration is presented and discussed in this paper.

The Air and Energy Engineering Research Laboratory (AEERL) has been investigating the injection of dry calcium hydroxide into combustion streams for the removal of sulfur oxides. It has been known, for some time, that the reactivity of Ca(OH)2 with sulfur oxides varies over a wide range for different batches of calcium hydroxide. The reactivity is a critical factor in the economics of the process. Because of this it is desirable to have a method to predict the reactivity of calcium hydroxide batches. The reactivity can be affected by many factors including the origin of the calcium carbonate mineral from which the hydroxide is produced, the production conditions, and the concentration of additives used for reactivity enhancement. It has been theorized that all of the preceding contribute to such physical characteristics as surface area, particle size, and porosity. The examination of these physical characteristics has provided the basis for understanding the reaction processes but has net provided all the factors necessary to correlate intrinsic sorbent characteristics with reactivity.

The development of linear position-sensitive detectors (PSD) has resulted in a large reduction of data acquisition times in the field of x-ray stress analysis. However, we also require two-dimensional (2-D) diffraction patterns for material evaluation. Especially, the microbeam x-ray diffraction technique gives valuable information on the structure of crystalline materials and this technique has been applied to fracture analysis by x-rays. Many kinds of 2-D PSD have been developed that have insufficient spatial resolution. So x-ray film has still been used as a 2-D detector, but it requires relatively long exposure times and then the process after exposure is very troublesome.

When an x-ray diffraction profile Is measured for stress analysis or profile analysis by the use of a linear (straight line) position sensitive proportional counter (PSPC) , a convex-type background line is obtained because of the geometrical problem and the absorption of x-rays. Such phenomenon is remarkable when a wide angular range is set on a linear PSPC and it is, in particular, necessary to correct with a straight background for accurate measurement of diffraction angle or half-value breadth of the broadened diffraction profile.

We have determined the strain and particle size for several samples of palladium powder by time-of-flight nrutron powder diffraction on two different diffractometers and by x-ray powder diffraction. The results are compared and found to be in fair agreement. The time-of-flight method gives good enough precision to reveal deficiencies in the simple models used for strain and particle size line broadening.

A numerical resolution-enhancement method was developed for x-ray diffraction data measured with a conventional x-ray diffractometer. This method removes the instrumental broadening due to x-ray optics, including the spectral distribution of the x-ray source such as the CuKα doublet. The advantages of this method are to separate the cluster of peaks in x-ray powder patterns into individual peaks without previous knowledge of the number of peaks, and to remove CuKα2 reflection peaks automatically.

The instrumental window function, which was approximated by a modified pseudo-Voigt function, was calculated from the measured diffraction pattern of NBS Standard Reference Materials (640B) by a non-linear least squares method. The simple diffraction patterns, including no CuKα2 peaks, were obtained from the diffraction patterns measured with the conventional x-ray diffractometer by using the window function mentioned above.

The application of the method of determination of the lattice misfit between γ and γ phases in Ni-base superalloys was also described.

In planning for PDF-3, the International Centre for Diffraction Data's full pattern database of raw diffraction data, it is evident that a standard format for storage and exchange of diffraction data is necessary. An evaluation of the JCAMP-DX protocol by a task group* of the International Centre for Diffraction Data has resulted in a set of format cooes specific to X-ray diffraction. The proposed structure of the data is divided into four parts: the minimal component set required by the JCAMP-DX definition (name, data, owner, sample identification, data type, etc.), a minimum item set required to define the X-ray diffraction data, an open selection of requested but not required information on the sample, its preparation and the instrument, and finally the data itself in one of several specified formats. All information stored in JCAMP-DX format is in ASCII characters. Therefore, these data are printable, easily read by the user and compatible with almost any computer or media storage device. Codes defining the information are primarily in shortened, but readable, English. The task group is completing the work on this project and will be presenting its proposals to JCAMP.

This paper summarizes our work on the structures of two wholly aromatic copolymers: the copolyamide prepared from terephthalic acid, phenylene diamine, and 3,4'-diaminodiphenyl ether (mole ratio 50/25/25) and the copolyester carbonate prepared from p-hydroxy benzoic acid and hydroquinone, with the introduction of carbonate units (mole ratio 60/20/20). X-ray fiber diagrams of both copolymers exhibit a number of aperiodic meridional maxima that are similar to those reported for a series of wholly aromatic copolyesters. The latter systems have been shown to consist of arrays of parallel chains of completely random comonomer sequence: the aperiodic maxima arise due to structural correlations along the extended random sequences. The structures studied in the present paper are more complex due to the presence of kinked units, i.e. the 1,3 phenylenes and ether linkages of the copolyamide, and the carbonate groups of the copolyester carbonate. The results obtained show that the x-ray data can be explained by completely random monomer sequences. However, the chains are significantly distorted in order to produce more extended conformations than might be expected for isolated chains. These distortions minimize the effects of the kinked units and lead to better chain packing.

Polystyrene has been commercially manufactured for over fifty years. Today it enjoys widespread application in appliances, food containers, packaging, toys and thermal insulation. Generally, the term polystyrene is used as a generic descriptor for “he atactic configuration of the polymer chain. In this context the term configuration refers to structural regularity with respect to the substituted carbon atom within the polymer chain. In atactic polystyrene (PS) the phenyl groups are distributed randomly along either side of the polymer backbone. (Figure 1). Since there is no significant degree of long range order along this chain the polymer will not crystallize to any appreciable level.

Pentaerythritol (PE) and neopentylglycol (NPG) are organic molecular crystals which have hydrogen-bonded lattices with layered- and chain-type structures, respectively. The PE undergoes solid-state phase transitions at 416K, from tetragonal to a cubic (γ’) structure and NPG also undergoes this transition at 317K from a monoclinic to a cubic (γ) structure. The phase transitions in binary PE-NPG solid solutions show more than one solid-solid transition in which the NPG-rich β transforms to γ at a constant temperature but the transition of the PE-rich a phase to γ’ passes through a two-phase field at a temperature that varies as a function of composition. Structural analyses by high-temperature x-ray diffractometry have revealed some new, interesting transitions. A phase diagram has been constructed for 0-30 mol% NPG in the PE-NPG system, using x-ray diffraction and differential scanning calorimetry results, and work is in progress to complete this diagram. The variation of lattice parameters as a function of temperature in the α, γ and γ’ phases for PE+20 mol% NPG are presented here, together with a discussion of phase transitions for certain compositions.

Two important factors, the progressively decreasing size of the lanthanides, which is known as the lanthanide contraction, as well as the stability of different oxidation states of these elements influence the prediction of compound formation in the Ba-R-Cu-O systems. A systematic investigation of these lanthanide systems and comparison with the Y system has revealed a correlation of the effect of the above factors, in particular the size factor, on the trend of phase formation, solid solution formation and phase compatibility diagrams of the Ba-R-Cu-O systems. For example, it has been found that the smaller the size of R3+ or the greater the mismatch betwaen Ba2+ and R3+ in the solid solution series Ba2-ZR1+lCu3O6+x, the smaller the extent of solid solution formation. This differing extent of solid solution formation influences the ternary phase relationships.

Zirconia(ZrO2) is one of a number of ceramic materials under development both at Dow and other companies for high cost, low-volume applications under severe corrosion/wear conditions. To improve the physical properties of zirconia, much work has been done worldwide in recent years developing partially stabilized zirconia, or PSZ. This is zirconium oxide which has been “stabilized” in the tetragonal form, typically by the addition of calcium or yttrium oxide. The term “partially stabilized” is given to these materials because the proper amount of oxide stabilizer will cause the zirconia to crystallize almost entirely in the tetragonal form under the proper processing conditions. However, the PSZ fabricated part is not completely stabilized, because it will undergo a tetragonal to monoclinic (T → M) phase transformation when subjected to an applied stress.

The mass absorption coefficient (μ) of a weakly absorbing solid material may be measured by either the transmission or the reflection method. The latter typically employs a crystalline substrate and the diffraction method, measuring the transmission of the diffraction peak(s) of the substrate through the analyte. Compressing or compacting a powdered sample is not required when the reflection method is used.

Manufacturers of household laundry products and laundry detergent builders want to know the exact formularies used in prospective customers' and competitive product lines. No convenient source exists for this information because published formularies are numerous and differ widely, (See Table 1.)

IARC's designation of crystalline silica as a “probable carcinogen” triggered the requirement to label products containing greater than 0.1 % crystalline silica. For perlite and other materials which may contain crystalline silica in levels close to 0.1% an accurate determination is critical from both legal and marketing considerations.

Existing analytical techniques for the determination of crystalline silica at levels of less than 1.0% were found to be inadequate to meet the new requirements. An improved technique based on x-ray diffraction has been developed specifically to analyze perlite for crystalline silica, which occurs largely in the form of quartz, at the 0.1%. level. The technique employs long counting times and improved sample preparation and mounting to increase both precision and accuracy, and to lower the detection limit to less than 0.1%.

The technique was tested on a large number of samples from a variety of sources and proven to give excellent results for all types of expanded perlites and perlite ores. The procedures developed are applicable to a wide variety of materials in addition to perlite.

The fundamental parameter approach for quantitative x-ray fluorescence analysis is an application of the equations derived by Sherman and by Shiraiwa and Fujino. Both derivations assume plane and smooth specimen surfaces and defined entrance and take-off angles of x-rays. Our investigation is dedicated to a more general description of measured characteristic signals. Consequently we have to deal with equations that allow us to account for the parameters mentioned below.

During this decade, several influence-coefficient algorithms have been published which utilize fundamental parameter equations to correct interelement effects in bulk samples. The Comprehensive Algorithm of Lachance (COLA) is one such algorithm and is used in the program NBSGSC(l). Another COLA-based computer program called FLY-FPM has been developed in China by one of the authors (L. Feng). Using FLY-FPM as a starting point, we developed a new COLA-based program as part of a Cooperative Research Agreement with Kevex Instruments. This program was designed for use with x-ray spectrometers that employ both tube and secondary targets for excitation. For direct tube excitation, the NIST tube spectral distribution algorithm is used in this program (2). For secondary target excitation, the radiation is usually treated as being monochromatic, and fundamental parameter expressions are formulated with this in mind.