Some Features of Quantitative Analysis of Rock-Forming Minerals Using a JXA-8230 Electron Probe Microanalyzer

—The basic software package of a JXA-8230 microanalyzer, like its predecessor JXA-8100, uses the long-established ZAF correction method (with some differences) for a quantitative analysis: Calculation of mass absorption coefficients is based on Chantler’s theoretical data. The core of this method is quantum-mechanical calculation of the cross section of the interaction between an X-ray photon and atomic electrons. This innovation has had a positive influence on the trueness of X-ray microanalysis. Control tests on specimens where the absorption effect is dominant have demonstrated that the results of this analysis are slightly lower (by less than 2%) independently of the matrix absorption interval in which the analytical line is located. As a consequence, the selection of comparison specimens becomes easier: It is sufficient that the specimen under study and the comparison specimen belong to the same isomorphic series and that the intensity of the analytical line of the comparison specimen allows for the measurement with the required accuracy.

Investigation on Laser Welding of Al Ribbon to Cu Sheet: Weldability, Microstructure, and Mechanical and Electrical Properties

The pulsed laser welding of Al ribbon to Cu sheet was investigated for the electrical interconnections in power electronic modules. The various experimental conditions with the different laser powers, scan speeds, and heat inputs were employed for obtaining the defect-free Al/Cu joints. During the Al/Cu laser welding, the intermetallic compounds were formed in the welding zone. An electron probe microanalyzer and transmission electron microscopy confirmed the phases of intermetallic compounds, which were found to be Al4Cu9, Al2Cu, AlCu, etc. The computational fluid dynamics simulation revealed that the Marangoni effect induced the circulation of the molten pool, resulting in the mixture of Al and Cu and the formation of swirl-like structures at the Al/Cu joints. The tensile shear strengths and electrical resistances of the Al/Cu joints were measured, and they showed a strong correlation with the welding area. A decrease in mechanical strength and an increase in electrical resistance were measured with increasing the welding area of Al/Cu joints. Moreover, the process window for the defect-free Al/Cu joints was developed, and the experimental conditions for Al/Cu laser braze-welding were examined to minimize the intermetallic compounds formation at the Al/Cu joints.

A New Constraint on the Physicochemical Condition of Mars Surface during the Amazonian Epoch Based on Chemical Speciation for Secondary Minerals in Martian Nakhlites

Iddingsite in Martian nakhlites contains various secondary minerals that reflect water–rock interaction on Mars. However, the formation processes of secondary Fe minerals in iddingsite are unclear because they include carbonates precipitated under reductive and alkaline conditions and sulfates that are generally precipitated under oxidative and acidic conditions. Mineral types cannot coexist under equilibrium. Herein, we characterize the carbonate phase of meteorite Yamato 000593 as siderite and Mn-bearing siderite via field-emission electron probe microanalyzer (FE-EPMA). Then, we examined the distribution and speciation of trace Cr and S within the carbonates through synchrotron micro-focused X-ray fluorescence-X-ray absorption fine structure and scanning transmission X-ray microscopy (μ-XRF-XAFS/STXM) analysis to estimate the transition history of Eh-pH conditions during siderite formation to explain the coexistence of carbonate and sulfate phases in the nakhlite vein. Specifically, the distribution and speciation of S in the mesostasis and carbonate phases and the heterogeneous distribution of Mn-FeCO3 incorporating Cr(III) in the carbonate constrain the Eh-pH condition. The conditions and transition of the fluid chemistry determined herein based on speciation of various elements provide a new constraint on the physicochemical condition of the water that altered the nakhlite body during the Amazonian epoch.

ANALYSIS AND PROSPECTIVE UTILIZATION OF TECHNOGENIC SLAG WASTE FROM A LEAD PLANT

The article presents the analysis and results of the study of technogenic slag waste of lead-zinc production. Slags of lead-zinc production contain a large number of toxic compounds: lead, zinc, osmium, cadmium, which are dangerous sources of environmental pollution. Due to the open storage of slags, it was found that the maximum permissible concentrations of lead were exceeded. Utilization of man-made slag waste is of great importance for reducing the negative impact on the safety of life and improving the environmental situation in the region. At the same time, slags are valuable raw materials containing compounds of non-ferrous and rare-earth metals. The article shows the results of laboratory studies of slags to determine the qualitative and quantitative composition of valuable components in the waste of lead production and the possibility of their further processing and disposal. Studies of the material of the heavy slag fraction were carried out on an electron probe microanalyzer of the JEOL IXA-8230 Electron Probe microanalyzer brand. X-ray diffractometric analysis of the average slag sample was performed on a DRON-4 diffractometer with Cu radiation, graphite monochromator. Samples were selected heavy fraction and manufactured artificial polished sections (briquettes). The sections were studied under the microscope of the brand LEICA DM 2500P and immersion in liquids. According to the results of research, it was found that lead slags contain a sufficiently high amount of non-ferrous metal compounds: lead oxide up to 0.7 % and zinc oxide up to 8.5 % of the weight amount of slag, which makes the process of recycling toxic waste from lead production technically and economically feasible.

Cryo-Structured Materials Based on Polyvinyl Alcohol and Hydroxyapatite for Osteogenesis

The application of various materials in biomedical procedures has recently experienced rapid growth. One of the areas is the treatment of many of different types of bone-related diseases and disorders by using biodegradable polymer-ceramic composites. We have developed a material based on cryogel polyvinyl alcohol, mineralized with calcium phosphate. Composites were obtained by cyclic freezing-thawing, the synthesis of calcium phosphates was carried out in situ under the influence of microwave radiation with heating and stirring. The components of the composites were determined using the methods of IR-spectroscopy and scanning electron microscopy and electron probe microanalyzer, as well as their morphology and surface properties. The biological compatibility of the material was investigated in vivo for a Wistar rat. The assessment of the quality of bone formation between the cryogel-based implant and the damaged bone was carried out by computed tomography. An improvement in the consolidation of the bone defect is observed in the bone with the composite in comparison with the control bone.

Chemical composition and age of monazite-(Ce) in granitoids of the crystalline basement from the South Yamal

The relevance of the work is due to the need to improve the method of chemical dating as applied to high-thorium accessory minerals, which are difficult to date by isotope research methods. Purpose of the work: study of the chemical composition of accessory monazite from granitoids of the crystalline basement of the South Yamal and determination of its age. Research methodology: quantitative analysis of the chemical composition of monazite was carried out using X-ray spectral electron probe microanalyzer CAMECA SX 100 (electron beam diameter from 1 μm, BSE, SE, Cat modes, determination of elements from beryllium to uranium). The spectra were obtained with the help of inclined wave spectrometers, the intensity was measured using analytical lines: Th Ma, U Mb, Pb Ma, Y La, Si Ka, Ca Ka, P Ka, Ce La, La La, Pr Lb, Nd La, Sm Lb, Dy La, Gd Lb. The age calculation was carried out according to the well-known methods of foreign authors in addition to some developments of the author. Results. The chemical composition of monazite makes it possible to classify it as a cerium variety, the content of radiogenic components varies greatly (in wt.%): ThO2 – 5.37–16.31, UO2 – 0.40–0.81, PbO – 0.08–0,19. There are significant concentrations of SiO2 (up to 3.5 wt.%), Y2 O3 (up to 1.8 wt.%) and CaO (up to 1.2 wt.%). It turns out that monazite implements hattonite (Th4+(U4+)+Si4+ → REE3++P5+) and cheralite (Th4+(U4+)+Ca2+(Sr2+,Ba2+,Pb2+) → 2REE3+) isomorphism types. The decent content of lead and high crystallinity of the substance makes it possible to use this mineral as a geochronometer mineral. Conclusions. New data on the chemical composition of monazite have been obtained, and the late Permian age of granitoids has been determined by microprobe dating. The values of the point U–Th–Pb ages of monazite together give a weighted average age of 256 ± 10 Ma (MSWD = 0.15) and an isochron of 254 ± 19 Ma (MSWD = 0.28), which almost ideally coincides with the results of isotopic U–Pb zircon dating from the same rock, 254 ± 3 Ma.

Mineralogy of Nickel and Cobalt Minerals in Xiarihamu Nickel–Cobalt Deposit, East Kunlun Orogen, China

Located in the East Kunlun Orogen, China, the Xiarihamu magmatic nickel–cobalt sulfide deposit is the country’s second largest deposit of this type. It was formed in special early Paleozoic with low copper grade (0.14 wt%) compared with other deposits of the same type. The mineralogy of nickel and cobalt minerals, which are direct carriers of these elements, can clearly reflect their behavior in the process of mineralization; however, such information for this deposit remains unreported. In the present study, we use an electron microscope and electron probe microanalyzer to delineate and analyze many nickel and cobalt minerals such as maucherite, nickeline, cobaltite, violarite, gersdorffite, parkerite, and arsenohauchecornite in various rocks and ores. With the increase in crustal material contamination, it can reach arsenide saturation locally in sulfide melt, then a separate Ni-rich arsenide (bismuth) melt exsolves somewhere. This melt will crystallize into nickeline, parkerite, arsenohauchecornite, and maucherite first. Second, most of nickel and cobalt tend to enter cobaltite and pentlandite phases, rather than existing in chalcopyrite and pyrrhotite phases as isomorphism during sufficient fractional crystallization of sulfide melt, which gathered nickel and cobalt elements widely. Also, more than one magma might result in the superposition of ore-forming elements. Later, the ore-forming elements redistribute limitedly through a hydrothermal process. The metallogenic mechanism model of nickel and cobalt established in the present study not only explains the process of nickel–cobalt mineralization in Xiarihamu but also can be applied to similar deposits and has a wide universal replicability.

Effect of SiO2–Al2O3 Glass Composite Coating on the Oxidation Behavior of Ti60 Alloy

A SiO2–Al2O3 glass composite coating was prepared on Ti60 alloy via air spraying slurry and then a suitable baking process. It was composed of potassium silicate glass, alumina and quartz powders. The high temperature oxidation performance of the alloy with and without coating was evaluated in static air at both 800 °C and 900 °C. The results show that catastrophic oxidation occurs for Ti60 bare alloy. It had a mass gain of about 2 mg/cm2 after oxidation at 800 °C and 17 mg/cm2 at 900 °C for 100 h. On the contrary, the oxidation resistance of alloy coated with composite coating was much improved with the mass gain about 0.36 mg/cm2 and 0.95 mg/cm2 at 800 °C and at 900 °C, respectively. The microstructure evolution of the composite coating and the alloy was analyzed by scanning electron microscope and electron probe microanalyzer. The effect of the composite coating on the oxidation performance of the alloy is discussed especially in terms of oxygen diffusion and interfacial reaction.