Electron Probe X-ray Microanalysis Research Articles

Chondroplasty Efficacy of Bone Matrix

Aim To study the chondroplasty efficacy of the bone matrix obtained using an original technology in restoring cartilage defect of the knee joint. Material and Methods Marginal defects were modeled on the surface of the distal end of the femur in 40 adult male Wistar rats. The bone matrix obtained using an original technology was implanted in the damaged area in animals of the experimental group. Material was investigated by means of light microscopy, transmission and scanning electron microscopy, and electron probe X-ray microanalysis. Results It was found that the bone matrix implanted did not cause an immune rejection reaction, activated reparative chondrogenesis for a prolonged period. In the area of articular cartilage lesion, the regenerate acquiring cellular and histochemical characteristics of the hyaline cartilage tissue was formed. The chondroinductive properties for the bone matrix were ensured by localized growth factors and morphogenetic proteins released during osteoclastic resorption. Conclusion The application of the bone matrix as a stimulator of chondrogenesis is theoretically reasonable and has a good perspective in treatment of damages and diseases of the articular cartilage.

Effects of preform aperture/hole wall ratio on the microstructure and properties of ZTAp/HCCI matrix honeycomb structure composites

Zirconia toughened alumina particles (ZTAp)/high chromium cast iron (HCCI) matrix honeycomb structure composites were successfully prepared by the non-pressure infiltration casting process. The transformations of ZTA ceramic particles and high chromium cast iron during the compound process were analyzed by using x-ray diffraction (XRD) and Electron probe microanalysis (EPMA). The maximum stress and average value of the maximum stress simulated by COMSOL Multiphysics software shows a trend of decreasing first and then increasing with decreasing preform aperture/hole wall ratios. The maximum stress and average value of the maximum stress are minimal among the six comparison groups and the stress range is 0.8 ∼ 1.8 GPa with preform aperture/wall ratio of 1.25. Owing to the change in the main impregnation resistances influenced by the hole wall value, the dispersion uniformity of ZTA ceramic particles in the composites becomes better with preform aperture/wall ratio of 1.43, 1.25 or 1.11. When the preform aperture/hole ratio is 1.25, the compressive strength of the samples reaches a maximum value of 1240 MPa. And the trend of the compressive mechanical properties is consistent with the results of the stress simulation. The wear volume loss of the composites reaches the smallest with preform aperture/hole wall ratio of 1.25, because the protective effect of ZTA ceramic particles and the supporting effect of high chromium cast iron achieve the best synergistic cooperation at this ratio.

Corrosion resistance by HVOF coating on gas turbine materials of cobalt based superalloy

Abstract In the parts of gas turbines, external degradations such as corrosion occur at places like turbine blades, when the temperature is high. The turbines become less operative and flare with sound because of the degradation due to corrosion. The thermocyclic hot corrosion performance of the 25%(Cr3C2-NiCr) + 75%NiCrAlY coatings as well as the cobalt based super alloy (Superco-605) substrate alloy was studied in a molten salt environment of Na2SO4 −50%V2O5 at 750 °C for 50 cycles. Each cycle consists of an hour heating followed by 20 min of cooling, in room temperature environments. The response and kinetics were studied by means of thermogravimetry. The samples subjected to corrosion will be investigated using techniques of Optical microscopy, X-ray diffraction (XRD), Scanning electron microscopy/Energy dispersive X-ray analysis (SEM/EDX) and Electron probe microanalysis. The major phases observed on coated material shows the formation of oxides of Chromium Oxide (Cr2O3), Nickel Oxide (NiO), and Aluminium oxide (Al2O3) which gives high protection against corrosion and prevents the penetration of corrosive species into the coating.

Experimental Liquidus Studies of the CaO-ZnO-Fe2O3 System in Air

Phase equilibria in the CaO-ZnO-Fe2O3 system have been investigated at 1483-1673 K (1210-1400 °C) for oxide liquid in equilibrium with air and solid oxide phases: (a) zincite (Zn,Fe,Ca)O1+x; (b) spinel (Zn,Fe,Ca)Fe2O4; (c) lime (Ca,Zn)O; (d) calcium ferrites dissolving zinc oxide: brownmillerite Ca2(Fe,Zn)2O5−x, and calcium diferrite (Ca,Zn)Fe4O7. High-temperature equilibration on inert metal (platinum) substrates, followed by quenching and direct measurement of the Ca, Zn and Fe concentrations in the phases with the electron probe x-ray microanalysis (EPMA) has been used to accurately characterize the system in equilibrium with air. All results are projected onto the CaO-ZnO-“FeO1.5” plane for presentation purposes. The present paper presents systematic characterization of liquidus over a wide range of compositions in this system in equilibrium with air.

Impact of MgO and K2O on Slag-Nickel Matte Equilibria

Slag chemistry of the direct nickel matte smelting was studied in typical industrial high-grade nickel matte smelting conditions at 1400 °C and 0.1 atm pSO2. The experimental technique used involved equilibration, quenching and direct elemental phase composition analysis by Electron Probe X-ray Microanalysis. Magnesia and potassia, a typical gangue constituent of sulfidic nickel concentrates and a common impurity of industrial grade silica flux (sand), respectively, were adopted as slag modifiers in concentrations typical to industrial operations. Their effects on oxidation degree of the nickel-copper-iron matte and equilibrium concentrations of Ni and Cu in the slag were studied as a function of oxygen partial pressure. Solubility of silica in the slag increased significantly with additions of MgO and K2O in the constrained case studied, at silica saturation. Equilibrium concentrations of Ni and Cu in the slag containing MgO and K2O were about a quarter lower compared to the pure iron silicate slag, in the entire oxygen partial pressure range studied.

PbI2 Single Crystal Growth and Its Optical Property Study

In this work, we used the chemical vapor transport (CVT) method to grow PbI2 crystals using iodine as a self-transporting agent. The crystals’ structure, composition, and uniformity were confirmed by X-ray diffraction (XRD) and electron probe microanalysis (EPMA) measurements. We investigated the band gap energy using absorption spectroscopy measurements. Furthermore, we explored the temperature dependence of the band gap energy, which shifts from 2.346 eV at 300 K to 2.487 eV at 20 K, and extracted the temperature coefficients. A prototype photodetector with a lateral metal–semiconductor–metal (MSM) configuration was fabricated to evaluate its photoelectric properties using a photoconductivity spectrum (PC) and persistent photoconductivity (PPC) experiments. The resonance-like PC peak indicates the excitonic transition in absorption. The photoresponse ILight/IDark-1 is up to 200%.

Evolution of the Structure and Mechanism of the Formation of Welded Joints of Medium-Carbon Steels upon Rotary Friction Welding

The structure of the contact lines and of the thermomechanically affected zone of welded joints of medium-carbon steels obtained by rotary friction welding have been studied using metallography and scanning electron microscopy supplemented with X-ray electron microprobe analysis. The results of the microhardness distribution over the cross section of the welded joint are presented. The phase transformations realized at each stage of the technological process of welding in the regions subjected to the thermodeformation influence have been analyzed. The results of the uniaxial tensile and impact bending tests supplemented by the fractography of the fracture surface are presented.

Thermodynamic description and simulation of solidification microstructure in the Co-Ti system

The Co-Ti binary system has been investigated by means of experimental measurements and thermodynamic calculations. In order to provide new phase relationship in the Co-Ti system, 9 key alloys were prepared by arc melting under vacuum. All alloys were examined for phase and composition analysis by means of X-ray diffraction and electron probe microanalysis after annealing at 900 °C for 60 days and 1000 °C for 30 days, respectively. The invariant equilibrium among liquid, L12 and C36 Laves phases was experimentally determined to be an eutectic with the reaction temperature at 1154 °C. A revised Co-Ti phase diagram is presented according to the present experimental results and reliable literature data. A consistent set of thermodynamic parameters for the Co-Ti system was then obtained by means of CALPHAD (CALculation of PHAse Diagram) approach. The present thermodynamic parameters can describe the experimental results satisfactorily. Scheil solidification simulation was employed to analyse the experimental microstructure of as-cast alloys. The calculated mole fractions of the constitution phases in a few key as-cast alloys are in good agreement with the experimental data obtained by the image J software. The present work indicated that the comprehensive application of the thermodynamic calculation and decisive experiment is an efficient strategy to obtain the desired solidification microstructure.

Experimental Liquidus Study of the Ternary CaO-ZnO-SiO2 System

Phase equilibria of the ternary CaO-ZnO-SiO2 system have been investigated at 1170 °C to 1691 °C for oxide liquid in equilibrium with air and solid oxide phases: tridymite or cristobalite SiO2 (up to two immiscible liquids), pseudowollastonite (CS) CaSiO3, rankinite (C3S2) Ca3Si2O7, dicalcium silicate (C2S) (Ca, Zn)2SiO4, tricalcium silicate (C3S) (Ca, Zn)3SiO5, lime (Ca, Zn)O, zincite (Zn, Ca)O, willemite Zn2SiO4 and hardystonite (melilite) Ca2ZnSi2O7, covering the ranges of concentrations not studied before. High-temperature equilibration on primary phase (silica) or inert metal (platinum) substrates followed by quenching and direct measurement of the Ca, Zn and Si concentrations in the phases with the electron probe X-ray microanalysis (EPMA) has been used to accurately characterize the system. Liquidus phase equilibrium data of the present authors for the CaO-ZnO-SiO2 system are essential to obtain a self-consistent set of parameters of thermodynamic models for all phases.

Effects of Cu Opening Size on the Mechanical Properties of Epoxy-Contained Sn-58Bi Solder Joints.

The effects of Cu opening size on the mechanical properties of epoxy-contained Sn-58Bi solder joints were investigated by a low-speed shear test. Eight sample types were fabricated with various Cu opening sizes and solder pastes. The Cu opening sizes of the component and substrate were 200 μm or 380 μm, respectively, and the component formed a Sn-3.0Ag-0.5Cu (SAC305) solder bump which was placed on the Sn-58Bi solder paste or epoxy Sn-58Bi solder paste printed on the substrate and then reflowed. The microstructures of the solder joints were observed using scanning electron microscopy (SEM), and the chemical compositions were analyzed by energy-dispersive X-ray spectroscopy (EDS) and electron probe X-ray micro-analyzer (EPMA). Epoxy was formed around the solder joints after the reflow process, improving the bonding strength of the epoxy-contained solder joints. Specifically, the bonding strength of the epoxy Sn-58Bi solder joints increased about 2.9 times in the 200 μm (opening size of component)/380 μm (opening size of substrate) sample. When the opening size of the component and substrate differed, a fracture occurred at the smaller opening size. On the other hand, a fracture occurred at the substrate side for the SAC305 (solder paste of component)/Sn-58Bi (solder paste of substrate) solder joints, while a fracture occurred at the interface between SAC305 and Sn-58Bi at the SAC305/epoxy Sn-58Bi solder joints for samples with the same opening size between the component and substrate.

Anti-wear properties evaluation of frictional sliding interfaces in automobile engines lubricated by copper/graphene nanolubricants

Owing to the significance of improving fuel economy, reducing emissions, and extending the durability of engine components, this study focused on the tribological performance of nano-additives. In this study, copper (Cu) and graphene (Gr) nanomaterials were dispersed in a fully formulated engine oil (5W-30) with different concentrations. The tribological trials were investigated under various speeds and loads, utilizing a reciprocating tribometer to mimic the ring/liner interfaces in the engine. The frictional surface morphologies were comprehensively analyzed using electron probe X-ray microanalysis (EPMA), field emission scanning electron microscopy (FESEM), energy dispersive spectrometer (EDS), and three dimensional (3D) surface profilometry to explore the mechanisms responsible for improving the tribological performance of the frictional sliding parts in the engine. The tribological test results illustrated that lubrication by nano-additives reduced the wear rate (WR) and friction coefficient (COF) by 25%–30% and 26.5%–32.6%, respectively, as compared with 5W-30. The results showed that this is a promising approach for increasing the durability and lifespan of frictional sliding components and fuel economy in automobile engines.

Behavior of Ga, In, Sn, and Te in Copper Matte Smelting

The distributions of Ga, In, Sn, and Te between copper-iron mattes and silica-saturated iron silicate slags over a wide range of matte grades 55 to 75 pct Cu were determined at 1300 °C using a gas-phase equilibration-quenching technique and direct phase composition analysis by Electron Probe X-ray Microanalysis and Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry. Alumina from aluminum, a typical minor element of electric and electronic copper scrap, and lime were adopted as slag modifiers for increasing the trace element recoveries. Gallium and tin were distributed predominantly in the slag, indium preferred sulfide matte at low matte grades and slag at high, whereas tellurium strongly favored the sulfide matte in particular in high matte grades. The slag modifiers alumina and lime had a minor impact on the distribution coefficients of gallium and tin, but for indium and tellurium the distribution coefficients were more strongly affected by the basic oxides. The strong tendencies of tin and tellurium to vaporize at the experimental temperature were confirmed.

The effect of exuviae ingestion on lysosomal calcium accumulation and the presence of exosomes in the hepatopancreas of Porcellio scaber

The hepatopancreas of isopods has major functions in food digestion and storage of carbohydrates and lipids. Also, it stores essential and accumulates xenobiotic metals in lysosomal granules within the two major cell types, the S- and B-cells of the tissue. A µCT study on moulting Porcellio scaber has shown mineral within the hepatopancreas lumen, when the animal has ingested their shed cuticle after moulting, suggesting recycling of mineral from the exuviae. This study aims to reveal if the lysosomal metal containing granules store calcium originating from the ingested exuviae. Therefore, we investigated the effect of cuticle ingestion on the elemental composition of the hepatopancreas granules of P. scaber, using electron probe X-ray microanalysis. For the preservation of diffusible elements, samples were high pressure frozen and freeze substituted in acetone and we used Propane-1,3-diol as a floatation medium for sections. We analyzed S- and B-cells of animals in the postmoult and intermoult stage that have ingested their exuviae and, as a negative control, cells from postmoult animals that have not ingested their exuviae. STEM and TEM were used for the investigation of the ultrastructure. Unexpectedly, the cryo-fixed samples contain numerous extracellular vesicles (exosomes) and many multivesicular bodies containing pro-exosomes. We show a significant increase of calcium, copper, zinc and sulphur within the metal granules upon exuviae ingestion, and, after 9 days, a reduction of calcium and zinc. The results indicate transitory storage of calcium from the exuviae within the metal granules and its subsequent utilization in cuticle mineralization.

Experimental Liquidus Studies of the Binary Pb-Cu-O and Ternary Pb-Cu-Si-O Systems in Equilibrium with Metallic Pb-Cu Alloys

Phase equilibria of the Pb-Cu-Si-O system have been investigated in the range 933-1938 K (660-1665 °C) for oxide liquid (slag) in equilibrium with solid Cu metal, liquid Pb-Cu alloy, or both solid and liquid metals, and solid oxide phases: (a) quartz, tridymite, cristobalite (SiO2); (b) cuprite (Cu2O); (c) lead silicates (PbSiO3, Pb2SiO4, Pb11Si3O17); (d) lead oxide (massicot, PbO); and (e) copper plumbite (Cu2PbO2). High-temperature equilibration on silica or copper substrates, followed by quenching and direct measurement of Pb, Cu and Si concentrations in the liquid and solid phases with the electron probe x-ray microanalysis (EPMA) has been used to accurately characterize the system in equilibrium with Cu or Pb-Cu metal. All results are projected onto the PbO-“CuO0.5”-SiO2 plane for presentation purposes. The present study is a continuation of the previous investigation of this system by the authors in a part of the silica and cuprite primary phase fields. Present data were later used to develop the thermodynamic models for all phases in this system.

Small-scale mechanical properties of constitutive phases within a polycrystalline cubic boron nitride composite

Micromechanical properties of a polycrystalline cubic boron nitride (PcBN) composite have been assessed by statistical analysis of data gathered from experimental massive nanoindentation. The mechanical study was complemented with electron probe X-Ray microanalysis, aiming to correlate relative B/N ratio and local hardness for individual cBN particles. Best-fit of experimental and deconvoluted data is achieved by considering five mechanically different phases, defined on the basis of chemical nature, TiN/cBN interface presence, ratio between residual imprint dimension and microstructural length scale as well as phase stoichiometry. In-depth local micromechanical and chemical analysis permitted to propose and validate, for the first time, the existence of a correlation between intrinsic hardness and phase stoichiometry for cBN phase. Finally, based on experimental data measured by nanoindentation and analyzed in terms of plastic index, toughness for the PcBN composite studied is estimated to range between 4 and 6 MPa·√m.

Experimental isothermal section of the Nb-Ni-Ru ternary system at 1100 °C

In the present work, the phase equilibria of the Nb-Ni-Ru system at 1100 °C were investigated via a combination of triple diffusion and equilibrated alloys. The samples were examined by X-ray diffraction and electron probe microanalysis. Three new ternary compounds, namely, τ1 (Nb5Ni13Ru2), τ2 (Nb(Ni1-xRux)3, 0.17 ≤ x ≤ 0.32) and τ3 (Nb(Ni1-xRux)3, 0.34 ≤ x ≤ 0.67), were discovered. The isothermal section of the Nb-Ni-Ru ternary system at 1100 °C consists of 10 single-phase regions, 20 two-phase regions, and 11 three-phase regions. The homogeneity ranges for phases in this system were established. In addition, the phases of the Nb-Ru binary system at 1100 °C were discussed, and the existence of compounds NbRu and NbRu2 was confirmed. The NbRu3 phase was not identified, but it should be the solid solution of Nb in Ru.

Experimental investigation of phase equilibria in the Al–Cr–Fe system

The literature of the ternary Al–Cr–Fe system was evaluated and major open questions were identified. Transition temperatures between α-Fe,Al (A2) – FeAl (B2) and FeAl (B2) – Fe3Al (D03) as well as solidus/liquidus temperatures in the Cr-rich corner were determined. The results from thermal analysis show a substantial decrease of the A2/B2 transition temperature with increasing Cr content at constant x(Al). Furthermore, a partial solidus and liquidus projection below 50 at.-% Al were created. Several partial isothermal sections have been studied with equilibrated alloys and diffusion couples. Therefore, complementary methods were used such as thermal analysis, electron microscopy, chemical analysis, X-ray powder diffraction and electron probe microanalysis. Equilibration experiments have been performed at 973 K, 1173 K, 1315 K, 1373 K and 1423 K and two partial isothermal sections at the two lowest temperatures were constructed indicating a solubility of 22 at.-% iron in the AlCr2 phase at 973 K.

Slag Cleaning Equilibria in Iron Silicate Slag\u2013Copper Systems

In this study, the equilibrium distributions of selected trace elements between molten iron-saturated copper alloy and selected iron silicate slags were measured, and the effects of silica fluxing on them. In addition to the copper and iron main components of the system, trace elements like antimony, gallium, germanium, gold, indium, and silver were added in experiments that spanned the temperature range of 1473–1573 K (1200–1300 °C). Experimental charges were quenched and prepared in polished mounts. In situ analyses of the resulting phases were made directly on the mounts without the need of phase separation prior to analysis. Electron probe X-ray microanalysis was used for concentrations at or above approximately 100 ppmw, and laser ablation-inductively coupled plasma-mass spectrometry for the lower concentrations in the slags. The very low slag concentrations of germanium, antimony, and indium obtained indicate that these elements can be removed from the slag by reduction, whereas gallium concentrations in the slag were high. Consequently, gallium removal from iron residues, such as zinc smelting jarosite, is difficult without volatilization. Based on the present observations, the industrial reduction processes for the treatment of smelting and refining slags as well as for the processing of iron residues, and extracting the reducible metal oxides and their metal values can be optimized. The target in fluxing should be to maintain the slag compositions with a silica concentration higher than about 28 wt%.

Formation Mechanism of Al2O3-Containing Inclusions in Al-Deoxidized Spring Steel

The source, characteristics, and mechanism of Al2O3-containing inclusions in Al-deoxidized spring steel were investigated using electron-probe X-ray microanalysis (EPMA). Spring samples were collected during vacuum degassing (VD) refining, in a tundish ladle, and after hot rolling, respectively. Based on primary inclusion components, seven types of inclusions were observed through the manufacturing process: Al2O3, Al2O3-SiO2, Al2O3-CaO, Al2O3-MgO, Al2O3-MgO-CaO, Al2O3-SiO2-MnO, and Al2O3-SiO2-CaO. The Al2O3 and Al2O3-SiO2 inclusions were mainly attributed to deoxidization products, less than 15 μm in diameter and with liquidus temperatures exceeding 1600 °C. For Al2O3-CaO inclusions, which were considered to be formed by the reduction of entrapped slag by Al dissolved in the steel, the Al2O3/CaO ratio obviously decreased with the increase of inclusion sizes. Most Al2O3-SiO2-CaO inclusions were less than 15 μm in diameter, with their composition close to that of the refining slag and a liquidus temperature near 1500 °C. The Al2O3-MgO and Al2O3-SiO2-MnO inclusions originated from inherent reactions between dissolved [Al], [Si], [Mn], [Mg], and [O] in the steel. Al2O3-MgO-CaO inclusions resulted from coalescence between Al2O3-MgO and Al2O3-CaO inclusions.

Distribution of Co, Fe, Ni, and precious metals between blister copper and white metal

ABSTRACT The distribution coefficients of Co, Ni, Ag, Au, Pd, and Fe at low concentrations between liquid copper and molten white metal (low-iron copper matte, ‘Cu2S’) were investigated experimentally as a function of temperature (1250–1350°C) and SO2 partial pressure (0.01–1 atm). The experimental technique involved samples equilibration at controlled temperature and gas atmosphere, followed by quenching and subsequent elemental analysis of equilibrium phases with electron probe X-ray microanalysis and laser ablation-inductively coupled plasma-mass spectrometry. The distribution coefficient of silver, nickel, gold and palladium between liquid copper and white metal indicated that they favour the blister copper whereas cobalt and iron distribute more to the white metal. The distribution coefficient of nickel, e.g. increased from 2.1 at 0.1–1.0 atm PSO2 and 1250°C to 3.2 at 1350°C. The distribution coefficients were only slightly dependent on temperature. The relatively strong dependence of the distribution coefficient of cobalt on PSO2 was discussed.