Line Scan Analysis Research Articles

Evaluating the interfacial toughness of GaN-on-diamond with an improved analysis using nanoindentation

An improved analysis of the interfacial toughness using nanoindentation induced blistering of thin films on stiff substrates is demonstrated on GaN-on-diamond. The Hutchinson-Suo analysis requires accurate measurement of blister dimensions, conventionally measured using 2-D line-scans from 3-D topographical maps. The new meteorology overcomes shortcomings of this technique by fitting the 3-D analytical solution of a clamped Kicrchoff plate to the topological map of the blister. This allowed for quantification of interfacial toughness of smaller blisters in GaN-on-diamond, previously assumed invalid for analysis due to inadequacies of the line-scan analysis. Three samples were investigated and found to have interfacial toughness ranging from 0.6–1 J m−2. Additionally, the relationship between residual stress in the GaN and interfacial toughness was investigated using photoluminescence spectroscopy. In all cases, the GaN was found to be under increased compression at the diamond interface by up to -0.81 GPa, although no correlation with interfacial toughness was observed.

Material Characterization of Follower Assembly of G5 155mm Gun Howitzer Breach Mechanism Block

Medium alloy steel is widely used as a material for guns and rocket launchers due to its high strength and excellent machinability characteristics. The purpose of this study is to determine the material properties of the follower assembly used in a breech block gun launcher which is significantly important f or t he future product improvement. The microstructure and the effect of alloying elements in the follower assembly is evaluated in this study. The SPECTRO Optical Emission Spectroscopy (ES) method is used to analyse the chemical composition of the material and the Field Emission Scanning Electron Microscope coupled with Energy Dispersive X-Ray (FESEM-EDX) were used to analyse the inclusions of the sample. Results of the ES chemical composition analysis found that Nickel (Ni) is the major alloying elements beside Molybdenum (Mo), Chromium (Cr), Manganese (Mn), Silicon (Si), Sulphur (S), and Carbon (C) while chemical mapping and line scanning analysis of FESEM-EDX on inclusions distributed in the material microstructure identified as a compound of Manganese Sulphur(MnS). Fine dendritic microstructure arrangement and distribution in the microstructure analysis showed that the sample had been quenching in the heat treatment process, which also played a significant role in the material characterization. From the analysis, it is found that the material can be defined as medium alloy steel that is also typical for high strength material for ballistic application.

Recycling and utilization assessment of steel slag in metakaolin based geopolymer from steel slag by-product to green geopolymer

This paper presents an experimental study that aimed to recycle steel slag waste as a supplementary material in metakaolin based geopolymer, resulting in a new type of geopolymer composites. The mechanical properties and microstructure analysis of geopolymer composites were carried out. The metakaolin based geopolymer composite (MGC) was prepared by a three-key parameter (the mole ratios of SiO2/Al2O3, Na2O/SiO2, and H2O/Al2O3) composition design method. The flexural strength and compressive strength test results show that the strength increment of MGC after 3 days is very limited. MGC exhibits the typical early strength property on compressive strength. Then, the steel slag powder (SS) was added to replace metakaolin to synthesize the steel slag-metakaolin based geopolymer composite (SSMGC) with the determined mix proportion. The strength test results indicate that the incorporation of SS contributes to the strength increment at a later age than MGC. The XRD patterns, SEM images, and EDS line scanning analysis indicate that SSMGC undergoes hydration in alkaline solution and accumulates hydrated calcium silicate gel with curing age besides the silica-alumina gel generated during geopolymerization. Due to the low content and low activity of steel slag active components, the degree of hydration and the amount of calcium silicate gel are inferior to the geopolymerization and silica-alumina gel caused by metakaolin, and ultimately lead to the relatively lower strength of SSMGC than that of MGC. However, the negative effect of adding SS to MGC on the mechanical strength becomes very small with curing age.

Ultrafine PdRu Nanoparticles Immobilized in Metal–Organic Frameworks for Efficient Fluorophenol Hydrodefluorination under Mild Aqueous Conditions

Ultrafine PdRu Nanoparticles Immobilized in Metal–Organic Frameworks for Efficient Fluorophenol Hydrodefluorination under Mild Aqueous Conditions

Abstract 3120: MMP-7 increases migration by decreasing intercellular cell junction complexes in prostate cancer microtumors formed by perlecan/HSPG2

Abstract Background: Polarized epithelium is stabilized by lateral cell-cell interactions via cell adhesion molecules (CAMs) and by cell-matrix interactions with basement membrane including with perlecan/HSPG2 (pln). Prostate cancer (PCa) patients with bone metastases have circulating pln fragments, with inverse correlation between MMP-7 staining and loss of pln in cancer tissue. Cleavage of pln by MMP-7 increases cell-matrix interactions and dysregulates cell signaling, permitting migration. We earlier showed pln domain IV-3 (DmIV-3) drives cell-cell cohesion and, when digested with MMP-7, drives cell dyscohesion. Methods: To evaluate the impact of MMP-7 and pln fragments on microtumor dyscohesion and cell migration, uniformly sized PCa microtumors were pre-formed in a microwell system. Pre-formed microtumors were transferred to Dm IV-3 or full length perlecan (FL pln) coated wells for 16-24 hrs. Microtumors were treated with MMP-7 alone or MMP-7 plus predigested Dm IV-3 fragments or MMP-7 plus FL pln fragments. For live cell imaging, tracking of migratory cells leaving microtumors was performed with Imaris software. Co-location of cell adhesion complex components was assessed with Imaris Spots. Results: Pre-formed microtumors cultured with DmIV-3 cleaved by MMP-7 showed lower Pearson's correlation values at cell boundaries compared to microtumors treated with intact Dm IV-3. Line scan analysis revealed E-cadherin and F-actin fluorescent signals were enriched and co-aligned in microtumors treated with Dm IV-3; enrichment and co-alignment were reduced when DmIV-3 fragments and MMP-7 were present. Track number detected per cell cluster was highest in the presence of FL pln fragments plus MMP-7 along with a measurable change in distribution of track displacement lengths of cells toward high values. Conclusion: Boundary reorganization promotes a migratory cell phenotype in microtumors treated with MMP-7 and DmIV-3 fragments. DmIV-3 fragments generated by MMP-7 cleavage can enhance cell dyscohesion by disrupting interactions between CAMs. Ongoing work will identify DmIV-3 fragment(s) positively associated with tumor dyscohesion that play key roles in secondary metastasis formation. Following patterns of dyscohesion of pre-formed microtumors provides a good model to study dynamic changes in intercellular junction components and quantitate cell migration patterns that foster circulating tumor cell formation and metastasis. Citation Format: Lissette A. Cruz, Tristen V. Tellman, Oleg Igoshin, Daniel Carson, Mary (Cindy) Farach-Carson. MMP-7 increases migration by decreasing intercellular cell junction complexes in prostate cancer microtumors formed by perlecan/HSPG2 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 3120.

Archaeometry and Analysis of Ceramic Materials from Ávila (Spain): Late-Vetton Evidence

From the archaeological excavations carried out during 2019/2020 in the walled Ávila city (Spain), numerous ceramic fragments of different chronologies have appeared that have allowed us to find settlement sequences in this city that place its beginnings before Romanization. The latest interventions allow us to know that the wall of Ávila has a Roman origin, and it was developed on an indigenous nucleus from the 1st century BC that received the Romanizing influence during the 1st century AD. In addition, it was possible to establish that the materials used for their preparation are consistent with the materials of the geological environment, which suggests a local origin. This paper presents the study of a set of ceramic samples using XRD, ICP/MS, SEM/EDX, and linescan analysis. A statistical analysis of the samples using the minor elements concentrations has suggested that even though the local origin, there were several production centers within painted ceramics that until now were always included as a single set. Finally, due to the importance of the “late-Vetton” or “late Iberic” ceramics (mid-1st century BC—middle of the 1st century AC) from the archaeological aspect, for the first time, these ceramics are studied in detail from chemical and mineralogical tests. It was discovered that these samples had been made in an oven that had not exceeded 800 °C due to the persistence of different phases after cooking.

Oxidative desulfurization of dibenzothiophene by magnetically recoverable polyoxometalate-based nanocatalyst: Optimization by response surface methodology

Abstract This research investigates the catalytic activity of a new core-shell structured nanocatalyst, which was prepared by surface modification of magnetic silica nanoparticles with Keplerate nano-porous molybdenum oxide-based polyoxometalate ({Mo132}), in oxidative desulfurization (ODS) of dibenzothiophene (DBT) in n-octane as simulated fuel (SF). The characterization of the as-prepared catalyst was performed by several methods including XRD, FTIR, VSM, TEM, HRTEM, SEM/EDS, HAADF-STEM EDX line scan, ICP-OES, and CHNS analysis. The optimization process and design of experiments were performed by response surface method with the principles of central composite design (CCD). The effects of reaction conditions including temperature (X1), O/S molar ratio (X2), and concentration of the catalyst (X3) were assessed on DBT removal efficiency. The statistical results showed that temperature was the most effective parameter in the process. Meanwhile, optimal conditions for DBT removal were attained when the dosage of the catalyst, O/S molar ratio, and temperature were 0.0074 g cat. g-1 SF, 20.7, and 58 oC, respectively. Moreover, a sulfur removal of 99.94% was obtained for SF using the prepared catalyst within 30 min under the optimal reaction conditions. The recovery of catalysts from the reaction medium was done with a magnet and the performance of the recovered catalyst showed no loss in activity after four test runs.

Impact of Top Electrodes on the Nonvolatile Resistive Switching Properties of Citrus Thin Films.

Natural citrus thin films on an indium tin oxide (ITO)/glass substrate were synthesized using the solution method for resistive random access memory (RRAM) applications. The results indicated that the citrus memory device possessed stable resistive switching behavior. For a clear understanding of the role of the interface reaction between the top metal electrode and the citrus film, we investigated the influences of various top electrode (TE) materials on the resistive switching in TE/citrus/ITO devices. In comparison with Au/citrus/ITO and Ti/citrus/ITO devices, the Al/citrus/ITO device can be reproduced with a DC voltage of more than 100 times while only showing a slight decrease in the ON/OFF ratio. In addition, the Al/citrus/ITO device exhibited a high ON/OFF ratio of over 104 and an outstanding uniformity, which was attributed to the fast formation of a native oxide layer (AlOx), as confirmed by the line scan analysis. This indicated that the interface layer, created by the redox reaction between the Al electrode and citrus film, played an important role in the resistive switching properties of TE/citrus/ITO structures. These findings can serve as design guidelines for future bio-based RRAM devices.

Study on the Performance of Titanium Materials Based on Nano Silver Particles in Orthodontic Healing.

Nanomaterials are used as a new type of antibacterial agent in clinical medical research projects due to their unique physical and chemical properties. In this study, silane coupling method was used to coat nano-silver particles on titanium sheets to make the smooth titanium surface have antibacterial properties. Scanning electron microscope to observe the surface morphology of silane coupling modified titanium plate, the shape and size of nano-silver particles, and the adhesion on titanium plate; X-ray energy spectroscopy and line scan analysis of each element on the titanium wafer; X-ray photoelectron spectroscopy quantitative analysis of surface elements on the titanium wafer. The experimental group was nano-silver modified titanium sheet, and the control group was smooth titanium sheet. The experimental results show that the titanium material loaded with nano-silver particles has better antibacterial performance in the orthodontic process than ordinary materials. This material is highly safe and can be promoted for use.

Phase transformation from PbS to PbSe:S in hot-wall deposition of nanocomposite thin film with evaporation sources of PbS and ZnSe

Simultaneous evaporation of PbS and ZnSe using hot-wall deposition was investigated to prepare nanocomposite thin films. X-ray diffraction patterns indicated that the films formed a phase mixture of ZnSe and PbSe, suggesting that an evaporation source of PbS phase-transformed to PbSe during a film deposition. Wavelength-dispersive spectroscopy indicated that the composite contains a small amount of S below 1 at.%. High-angle annular dark-field scanning transmission electron microscopy and line scan analysis in electron energy-loss spectroscopy indicated that PbSe nanocrystals were dispersed in a ZnSe, while S tended to segregate in ZnSe matrix. Photocurrent spectra indicated that peak position at approximately 460 nm shifted toward a shorter wavelength as Pb concentration increased.

Effect of different ceramic materials and substructure designs on fracture resistance in anterior restorations

Statement of problemMaterials have been developed to reduce the chipping of ceramic veneer and improve the esthetics of anterior ceramic veneered restorations. However, studies of the effects of material and substructure design on fracture resistance are sparse. PurposeThe purpose of this in vitro study was to investigate the fracture resistance of metal-ceramic (MC), zirconia-feldspathic porcelain (ZC), and zirconia-lithium disilicate (ZL) anterior restorations and evaluate the effect of material and substructure design. Material and methodsAfter preparing and scanning artificial maxillary central incisor teeth, titanium abutments and restoration specimens (n=90) were fabricated. MC, ZC, and ZL materials were prepared with substructure designs A (two-third coverage of the palatal surface) and B (one-third coverage of the palatal surface). After cementation, the specimens were thermocycled (10 000 cycles, 5 and 55 °C). Fracture load measurements, failure mode analysis, energy dispersive X-ray spectroscopy (EDS), line scan analysis, fractography, finite element analysis (FEA), and Weibull analysis were performed. Two-way ANOVA was used to identify the effects of material and substructure design on fracture load. One-way ANOVA was used to identify significant differences of fracture load (α=.05). ResultsMC and ZL showed significantly higher fracture load than ZC (P<.05). MC_A showed a significantly higher fracture load than MC_B (P<.05). ZC_A exhibited the lowest Weibull modulus. FEA revealed that the maximum principal stress occurred near the loading area of the veneer. ZL displayed the lowest maximum principal stress among all the materials. ConclusionsZL and MC_A exhibited more favorable fracture resistance. The substructure design of MC, with increased metal coverage of the palatal surface, improved fracture resistance significantly.

The analysis of freshwater pearl mussel shells using \xb5-XRF (micro-x-ray fluorescence) and the applicability for environmental reconstruction

Freshwater pearl mussel is a highly threatened species, and many populations are currently on the brink of local extinction. For example, in south Finland, only two populations are currently viable. Even though the reasons for the mussels’ demise are relatively well known, the long-term impacts of water quality are not completely resolved. Here, µ-XRF analysis and historical records were used to evaluate whether the differences in water chemistry or past environmental changes in three rivers in southern Finland are visible in mussel shell chemistry. The results show that the cracks inside mussel shells, invisible to the naked eye, may greatly affect the elemental composition results. Further, anomalies which could be related to inclusion of detrital matter inside the shells were detected. Manganese (Mn) seems to be related to mussel growth dynamics, especially in the nacreous layer, while high values of iron (Fe) and Mn are also present at the top sections of the prismatic layer. Line scan analysis revealed high variation between replicates. The µ-XRF method could be used as prescreening method in mussel sclerochemistry studies, but more studies are needed to clarify the ability of FPM shells to reliably record the environmental conditions.

Automated Linescan Analysis for CMP Modeling

Many of the process steps used in semiconductor chip manufacturing require planar (smooth) surfaces on the wafer to ensure correct pattern printing and generation of multilevel interconnections in the chips during manufacturing. Chemical-mechanical polishing/planarization (CMP) is the primary process used to achieve these surface planarity requirements. Modeling of CMP processes allows users to detect and fix large surface planarity variations (hotspots) in the layout prior to manufacturing. Fixing hotspots before tape-out may significantly reduce turnaround time and the cost of manufacturing. Creating an accurate CMP model that takes into account complicated chemical and mechanical polishing mechanisms is challenging. Measured data analysis and extraction of erosion and dishing data from profile linescans from test chips are important steps in CMP model building. Measured linescans are often tilted and noisy, which makes the extraction of erosion and dishing data more difficult. The development and implementation of algorithms used to perform automated linescan analysis may significantly reduce CMP model building time and improve the accuracy of the models. In this work, an automated linescan analysis (ALSA) tool is presented that performs automated linescan delineation, test pattern separation, and automatic extraction of erosion and dishing values from linescan data.

Rapid elemental composition measurement of commercial pellets using line-scan hyperspectral imaging analysis

The use of biomass pellets as a renewable energy source is increasing, leading to the need for rapid assessment of biofuel pellet quality for production monitoring. The purpose of this work was to use line-scan near-infrared (NIR) hyperspectral image technology coupled with chemometric tools to assess the elemental components of biomass pellets. The parameters influencing model performance were investigated, i.e. wavelength and spectral pretreatment technique. Either full wavelength or partial wavelength selected using interval successive projections algorithm (iSPA) and interval genetic algorithm (iGA) were investigated. Either raw spectra or pretreated spectra were used for model development. The models were developed using partial least squares regression (PLSR). The most effective model for the prediction of carbon (C), hydrogen (H), and nitrogen (N) content was developed using iGA wavelength selection and standard normal variate (SNV) spectral pretreatment and provided the highest accuracy with a coefficient of determination of prediction set (r2p) and standard error of prediction (SEP) of 0.83 and 1.33%; 0.84 and 0.17%; and 0.90 and 0.098%, respectively. The model could be used for quality assurance. The S content model was poor and not recommended. The relationship between pellet chemical parameters and reflectance characteristics could be used for predicting C, H, and N of biomass pellets.

Enabling directional ion transport over graphene electrode surfaces for kilohertz electrochemical capacitors

The filtering capacitor is an electrochemical energy storage device, which can realize signal stabilization from alternating current to direct current in the modern electronic circuits. Traditional filtering capacitor, an aluminum electrolytic capacitor is usually limited by the bulky and rigid configuration. The graphene-based electrochemical capacitor with a fast frequency response has the potential to be the next-generation filtering capacitor. Kilohertz electrochemical capacitor with alternating current line-filtering performance requires the microstructural engineering of graphene electrodes to facilitate effective electrolyte ion permeation. Vertically-oriented graphene electrode-based electrochemical capacitor by microstructural engineering provides a significant solution for improving the filtering performance, but the underlying mechanism by which the vertical orientation endows graphene electrodes with the fast frequency response is still not clear. Therefore, a fundamental understanding of this mechanism must be developed and improved to ensure the design of superior kilohertz electrochemical capacitors for effective filtering. Here, a vertically-oriented graphene macroporous membrane is prepared to enable directional ion transport over the electrode surface at high frequencies, which is demonstrated by all of the electrochemical analysis, line scanning, schematic illustration and finite element analysis simulation results. Compared with those based on conventional horizontally-oriented and unordered graphene macroporous membrane electrodes, the vertically-oriented electrode-based electrochemical capacitor exhibits excellent filtering performance. Furthermore, it can convert arbitrary alternating current waveforms to straight signals. This work advances the understanding of the mechanism underlying the kilohertz frequency response and enables directional ion transport over the surface of vertically-oriented graphene electrodes, providing new insight into the search for future kilohertz filtering capacitors.

Activation of the Oxygen Reduction Reaction at an Interface-Regulated Pt/Nb-SnO2 Catalyst

The sluggish oxygen reduction reaction (ORR) kinetics on carbon-supported Pt catalysts has impeded the large-scale commercialization of polymer electrolyte fuel cells (PEFCs). More active ORR electrocatalysts are highly desired to improve PEFC performance with low Pt cathode loading. The adoption of alternative support material such as doped SnO2 represents a promising way forward for improving the activity of Pt-based catalysts while maintaining high durability.1 However, the correlation between the microstructure of the Pt/doped SnO2 and ORR activity remains ambiguous. In the present work, we, for the first time, show that the ORR kinetics of Pt can be boosted by the PtSn alloy formed at the interface between the loaded Pt nanoparticles and the Nb-SnO2 support.The Nb-SnO2 support was synthesized by the flame oxide-synthesis method. The Pt nanoparticles were loaded on the Nb-SnO2 by the colloidal method. The Pt loading amount in the Pt/Nb-SnO2 catalyst was determined by plasma-mass spectroscopy (ICP-MS). The microstructure of the Pt/Nb-SnO2 was characterized by scanning transmission electron microscopy with energy dispersive X-ray spectroscopy (STEM-EDX). A commercial catalyst c-Pt/C (TEC10E30E, TKK) was used for comparison. The electrochemical measurements were carried out by use of the rotating disk electrode (RDE) technique from 20 to 80 oC. The experimental procedure was the same as that described earlier.1 All of the electrode potentials in this paper are given versus the reversible hydrogen electrode (RHE).The Pt loading of Pt/Nb-SnO2 was measured to be 16.3 wt.%. The catalyst was uniformly dispersed on the support with an average Pt particle size of 2.7 ± 0.5 nm. EDX line scan analysis shows that Sn diffused into the Pt particle to form a PtSn alloy near the interface between Pt and Nb-SnO2, as illustrated in Fig. 1a. As shown in Fig. 1b, the Pt/Nb-SnO2 achieved 1.54 times higher specific activity and 1.47 times higher mass activity than c-Pt/C. Fig. 1c shows Arrhenius plots of the apparent rate constant k app for the ORR. Good linear relationships between the logarithm of k app and 1/T are observed for both electrodes. The k app values for c-Pt/C and Pt/Nb-SnO2 at 80 °C were, respectively, about 12 and 7 times higher than those at 20 °C. Thus, elevating the operating temperature significantly enhanced the ORR kinetics, which makes it possible to reduce Pt loadings in PEFCs. The apparent activation energy E a of c-Pt/C was calculated to be 36 kJ mol-1, which is well consistent with the result of Yano et al.2 Impressively, Pt/Nb-SnO2 exhibited a lower E a, 27 kJ mol-1, which is responsible for the high k app. The enhanced ORR kinetics is ascribed to the modified adsorption of oxygen species on the Pt surface by the PtSn alloys at the support-Pt interface, as revealed by DFT calculations. Acknowledgement This work was supported by funds for the JSPS KAKENHI Grant Number 20H02839 from the Japan Ministry of Education, Culture, Sports, Science and Technology. We are also grateful to Prof. Minoru Inaba and Prof. Hideo Daimon from Doshisha University for kindly providing the instruction of the RDE system (controlling temperature).

High Temperature Cyclic Oxidation of Ni-based 800H Superalloy at 700°C in Air

The high temperature cyclic oxidation has been investigated on 800H superalloy, composed of Fe-33Ni-19Cr alloy at 700? for 150 cycles in laboratory air. Two types of samples has been used, where the Fe-33Ni-19Cr alloy has been experienced a different heat treatment temperatures, which are 1000? and 1100?, which has differ grain size. The alloy was subjected to a short oxidation period at 700? for one hours, followed by cooling for 20 minutes for each cycle. The oxide phase analysis has been analyzed using x-ray diffraction (XRD) technique. The cross sectional line scan analysis has been examined using field emission scanning electron microscope (FESEM) equipped with energy dispersive x-ray (EDX) spectrometer. The phase analysis recorded four types of structure has formed on the oxidized sample, composes of austenite phase represent the base metal, corundum oxides, spinel oxides and fluorite oxides structure. The cross sectional analysis indicate that the oxidized samples were formed a several oxide layer, mainly compose of Cr-Mn and Cr-Ti rich oxide with detection of internal oxide precipitates compose of Al-oxide and Si-oxide precipitates.

Effect of YSZ sol-gel coating on interaction of Crofer22 APU with sealing glass for solid oxide fuel/electrolysis cell

Interactions between the metal interconnect and glass sealant in the solid oxide cells stack are critical to retaining the system integrity. To address this issue, in the current study, 8YSZ coating is applied on the Crofer22 APU steel via sol-gel and dip-coating method. Dense and continuous 8YSZ coatings are obtained on Crofer22 APU substrates. X-ray diffraction and Raman spectroscopy results show that both cubic and tetragonal structures of 8YSZ are formed. A glass-based sealing paste is applied on bare and 8YSZ coated Crofer22 APU steel. The interfacial compatibility and chemical stability of steel/glass and steel/8YSZ/glass joint couples are investigated using SEM and EDS line scan analysis after the sealing process as well as 1000 h (10 thermal cycles) aging at 800 °C in air atmospheres. Very good compatibility is found between the coated steel and the glass. No significant interactions, cracks formation, or failure are observed at both steel/8YSZ and 8YSZ/glass interfaces, suggesting that the YSZ protective layer can effectively act as a barrier to interdiffusion of metal and glass elements. Finite element analysis shows that the generated residual stresses in the presence of the coating layer are not significant to be detrimental for the examined interfaces.

The Joint Properties of A564-630 Stainless Steel Made by Transient Liquid Phase Bonding: Microstructural and Mechanical Strength Evaluation

Nickel-based filler alloy with a liquidus temperature of 1024 °C was used for transient liquid phase (TLP) bonding of A564-630 martensitic precipitation hardening stainless steel. TLP experiments were carried out at a constant temperature of 1050 °C for different times between 30 to 90 min employing 75 μm thick filler metal to achieve the best TLP parameters. A Ni coating of 10 μm was coated to the base materials to compare the joints with and without coating. The effect of bonding conditions on the microstructure and mechanical properties of samples was investigated. The isothermal solidification was achieved after 60 min of bonding time. The results showed that bond shear strength increased with increasing the TLP time. The Ni coating improved the microstructure and shear strength of the joint and the Ni-coated base metal TLP bonded at 1050 °C for 90 min showed lap-shear strength of maximum 461 MPa. By comparing the results of the line scan analysis and the hardness profile, it is concluded that with increasing the TLP time, a more uniform distribution of alloying elements and hardness profile across the joint region was achieved.

A comparative study on the micro-surface characteristics at black shale initial oxidation stage

The pyrite oxidation is crucial to the overall black shale oxidation process. A. ferrooxidans was documented an effective oxidation ability on pure pyrite, but its role in black shale oxidation is unclear. In this study, a comparative study of acid solution and A. ferrooxidans on the micro-surface characteristics at the initial stage (7 days) was conducted on black shale slices, a comprehensive approach combining the micro-morphologies, micro-structures, micro-environmental pH and micro-surface elemental content were investigated by using polarizing microscopies, SEM, fluorescent staining and EDX line scan analysis. The pyrite oxidation rate was employed to the index for black shale oxidation degree, and analyzed by XRD, aqueous pH, oxidation-reduction potential (ORP), ferrous and ferric ions concentrations measurement. The results show that the micro-surface characteristics are different in acid solution and A. ferrooxidans groups, which significantly impact the pyrite oxidation rate. A. ferrooxidans promote the jarosite formation and elemental C accumulation on the rocks micro-surface, which is assumed to inhibit further reactions. Two reaction phases named “pyrite oxidized phase” and “jarosite formation phase” are proposed to occur in the initial stage of A. ferrooxidans oxidizing black shale. These findings provide experimental data to evaluate the micro-surface reactions during black shale oxidation process.