Analyses of lubricating oils from aircraft engines, gear boxes and other lubricated mechanisms have been routinely performed by the military since the 1960's. The monitoring of the wear metal concentrations in the oil can lead to an early detection of abnormal wear and, consequently, the prevention of a malfunction or a complete failure of the aircraft. At the present time, almost all the analysis programs use atomic emission (AES) and/or atomic absorption (AAS) spectroscopy to determine elemental concentrations in the oils (1). These types of analysis require the close support of a laboratory to minimize the delays in obtaining the results of the measurements. The AES and AAS methods are very inefficient for particles 3 - 6 μm in size and are essentially blind to particles larger than 6 - 10 μm (2,3).

Trace elements in oil may be determined by adsorption of the oil sample onto maguesium oxide followed by thermal degradation of the organic material. The resulting powder is easily pressed into a pellet suitable for X-ray spectrometric analysis. The lower limit of detection depends upon the trace impurities in the MgO and is a few parts per million for most elements determined.

Metallic impurities present in crude oils lead to the rapid deactivation of catalysts used in refineries and a drop in the yield of oil products. The determination of these impurities is therefore of primary importance. The conventional and most widely used methods to determine trace metals in oils and petroleum products are chemical analysis methods such as atomic absorption spectrometry (AAS) and inductively coupled plasmaoptical emission spectrometry (ICP-OES). Sample preparation for these methods includes decomposition of the crude sample by dry ashing and combustion of the oil sample followed by chemical treatment of the dry ash residue (ASTM, 1983; Fassel et al., 1976). Major drawbacks of chemical analysis methods are the length of time required to prepare the sample and the possibility of losing trace metallorganic compounds in the form of volatile compounds.

Sophisticated matrix correction techniques have been successfully applied to analysis in an interactive laboratory environment (1-3). The present paper describes their application, to an on-line industrial environment, where reliable operation is to be maintained with a minimum of operator intervention. Out of bound situations must be detected and corrected automatically to the extent possible. Programming must be substituted for human judgement, within restricted circumstances.

X-ray fluorescence spectroscopy is usually not considered a surface technique in the same sense as ESCA or Auger spectroscopies. However, it can be a useful tool in studying the “surface” and bulk concentrations of elements in heterogeneous catalysts. The “surface” is defined by the effective penetration depth of the analyte line of the element of interest in a specific matrix. In the example which is presented, silver on alumina, the “surface” using the Ag KB1,3 is defined by a shell 3000 microns deep while for the Ag LAI it is 15 microns. Two methods of sample preparation are discussed and data obtained using three different calculation methods is presented. Data from the x-ray fluorescence method is compared to the silver depth profile in the alumina pellets obtained by electron microprobe analysis. The XRFS method allows rapid screening of many catalyst samples for the fraction of the cost of the microprobe technique.

Traditionally x-ray spectrometers have been designed to analyze perfectly prepared specimens that are flat and highly polished such as 32mm discs. Certainly the best analytical results are obtained on such samples, however in an industrial laboratory it is also neccessary to obtain statistically valid results on samples that are less than ideal in size and geometry. The problem at the TRIDENT Refit Facility is to analyze large metal parts such as pump casings, valve bodys, flanges, and finished piping sections that are going into the repair of TRIDENT class submarines. Energy dispersive X-ray techniques have long been recognized as fast and non-destructive and are therefore ideally suited to the analysis of these finished metal parts.

Different geometries are considered for source excited energy-dispersive X-ray fluorescence (EDXRF) analysis Systems, including the recessed source geometry introduced in the present work. The calculated physical excitation-detection efficiencies, for the side (or annular), central, receded and recessed source geometries are presented as a function of the target to source distance, for Ca, K, S and Si targets excited with a Fe-55 XBF-3 X-ray source and xenon filled gas proportional scintillation counters. The last two geometries present in gênerai the highest efficiencies. The recessed source geometry présent the best performance with peak efficiencies a factor of 3.3 better than those for the standard side or annular source geometries.

Method validation is vital for regulatory and nutrient analysis of foods, and imposes criteria for representative sampling and analysis along with more common requirements for precision and accuracy. When solid food samples are directly analyzed by x-ray fluorescence (XRF), they must be homogeneous on a mass scale at least similar to that penetrated by the interrogating and fluorescent x-ray beams. This mass varies with x-ray energy, and hence with the elements being determined, and few data are available documenting the scale on which homogeneity can be assured. This paper examines the effective sample masses that are represented in measuring 21 different elements in pelletized dry food samples, and also the homogeneity of mimerous foods and biological standard reference materials.

Silica-alumina refractory materials are used as insulation materials in high temperature applications. Such materials are amenable to x-ray analysis (1). Wavelength dispersive x-ray spectrometry is used in our laboratory for the analysis of a variety of refractory materials. An analysis procedure was needed for a quality control project that would provide major and minor element determinations in silica-alumina refractory materials. The requirements for the analysis scheme were relative accuracy and precision to be better than one percent. The method had to be rapid, simple to use, and inexpensive. Energy dispersive x-ray spectrometry and a borate fusion technique were chosen as the method of choice for this application. Described in this paper are the sample and standard preparation procedures, data reduction methods, and analytical results.

This study was done to learn which elements are being contributed as contaminants in the sample preparation equipment used at the New Mexico Institute of Mining and Technology (NMIMT). The apparatus investigated included a steel jaw crusher, a ceramic jaw crusher, two aluminum plates as a crusher and grinder, a steel spinning plate pulverizer, an alumina ceramic spinning plate pulverizer, an automated agate mortar and pestle, a high speed spectromill grinder with a tungsten carbide mortar and pestle, and the halves of a sliced quartzite cobble. Major-element Oxides and trace elements were analyzed by x-ray fluorescence. Some of the trace elements were analyzed by instrumental neutron activation analysis. The expected contamination of ferroalloy elements from steel were present in varying quantities, as were tungsten, tantalum and cobalt fron the tungsten carbide. There was unexpected contamination of sulfur and lead from the steel pulverizer.

Outokumpu Company has gone a long way in the last 20 years in the development and application of WDXRF-techniques in on-stream analysis of slurries in ore concentrators. The applications in which the samples were in solution form came only about 4 years ago when these analyzers were used for the first time in hydrometallurgical plants, During the past 15 years many improvements have been made in most parts of the equipment to Biake the performance and reliability better. The most important work to improve the analytical capability of the analyzer has been done on the spectrometers and detectors. This has resulted in better sensitivities and has given the possibility to go down to ppm levels in many determinations. The technical details of the improvements have been presented in several papers (1-4).

This method describes the addition of cerium (IV) oxide to a lithium borate flux. CeO2 provides a non-analytic glass former to the melt production. CeO2 also acts as an interelemental buffer replacing the use of lanthanum oxide for long wavelength absorption. With cerium oxide addition, excellent results are produced, resulting in part from the elimination of recrystallization problems encountered with lanthanum oxide use. Analytical results easily meet the ASTM C-114 qualification requirements for rapid method analysis of hydraulic cements.

Particle-size effects can cause significant errors in x-ray fluorescence (XRF) analysis of particulate materials. The effects are usually removed when samples are fused or dissolved to standardize the matrix for quantitative analysis. Recent improvements in numerical matrix corrections reduce the need to standardize the sample matrix via fusion or dissolution, particularly when the CEMAS method is used to estimate unmeasured light-element components of undefined materials for matrix calculations. A new method to correct for particle-size effects has therefore been examined to potentially avoid the need for destructive preparation of homogeneous samples.