Silicon carbide deoxidizer is a kind of high-performance complex deoxidizer. The determination of titanium content can trace the elemental introduction and loss in smelting process, thus more effectively improving the properties of steel. The composition of silicon carbide deoxidizer is complicated. In this study, the sample was treated by melting at high temperature. Sodium carbonate and sodium peroxide were used as mixed flux. The nickel crucible containing sample and mixed flux was heated in high-temperature furnace at 400 ℃. Then the temperature was increased to 900 ℃ and kept for 30 min to melt the sample. After complete fusion, the sample was leached with hot water and acidified with hydrochloric acid. After dilution to the mark, the solution was filtered. Ti 334.941 nm was selected as the analytical line for titanium. The calibration curve was plotted by matrix matching method. The content of titanium in filtrate was determined by inductively coupled plasma atomic emission spectrometry (ICP-AES). Consequently, the determination of titanium in silicon carbide deoxidizer was established. The linear correlation coefficient of calibration curve for titanium was above 0.999 9. The limit of detection was 0.000 5% (mass fraction). The content of titanium in silicon carbide deoxidizer sample was determined according to the experimental method, and the relative standard deviation (RSD, n=7) of measurement results was 2.0%. The spiked recoveries were between 98% and 102%. The contents of titanium in seven silicon carbide deoxidizer samples were determined according to the experimental method and spectrophotometry in national standard GB/T 16555-2017. The results were consistent.

The accurate determination of silicon content in chromium carbide is of great significance for the quality control of products. The sample was fused with sodium peroxide. After leaching with hot water and acidification, chromium was removed by volatilization with hydrochloric acid. Under certain acidity conditions, silicon could react with ammonium molybdate to form silicon molybdenum yellow. The mixture of oxalic acid and sulfuric acid was added to eliminate the interference of phosphorus and iron, and ascorbic acid was added to reduce silicon molybdenum yellow to silicon molybdenum blue for spectrophotometric determination at 810 nm. Thus, a method for determination of silicon in chromium carbide was established by silicon molybdenum blue spectrophotometry with alkali fusion. The results showed that the mass concentration of silicon in range of 0.05-1.20 μg/mL showed good linear relationship with its corresponding absorbance with correlation coefficient of 0.999 9. The apparent molar absorptivity was ε=22.41×10³ L·mol^-1·cm^-1. The limit of detection and limit of quantification for this method were 0.001 7% and 0.005 2%, respectively. The interference tests of coexisting ions showed that the residual chromium in test solution as well as phosphorus and iron in sample had no interference with the determination of silicon. The contents of silicon in three chromium carbide samples were determined according to the proposed method, and the relative standard deviations (RSD, n=9) were between 0.51% and 5.8%. Two chromium carbide samples were conducted for standard addition recovery tests, and the recoveries were between 97% and 102%.

It is of great significance for ecological environment protection to determine accurately and efficiently volatile phenol content in sediment. The liquid-solid ratio was controlled at 15∶1. Volatile phenol in the sample was extracted with 10 g/L sodium hydroxide solution after oscillation at 180 r/min for 15 min. Meanwhile, 3.0 g of copper sulfate was added to remove the interference of sulfides in the sample. Thus, the determination of volatile phenol in sediment was realized by flow injection analyzer. The results showed that the mass concentration of volatile phenol in range of 0.02-1.0 mg/L exhibited linear relationship to its corresponding peak area with correlation coefficient of 0.999 9. The limit of detection and lower limit of determination for this method were 0.08 mg/kg and 0.32 mg/kg, respectively. Three sediment samples with different concentrations of volatile phenol content in sediment were determined according to the proposed method, and the relative standard deviations (RSD, n=6) of determination results were between 0.83% and 1.4%. Two types of sediment sample were selected for recovery tests with three content levels, respectively. The recoveries were between 93% and 104%. The contents of volatile phenol in six sediment samples were determined according to the proposed method as well as 4-ampyrone spectrophotometry in standard method of HJ 998-2018. The results of the two above methods were basically consistent.

In order to improve the flexible analysis capability of laser-induced breakdown spectroscopy(LIBS) under various extreme environments, the miniaturization design of remote LIBS instrument was realized in this study. The instrument adopted modular design, and the tripod head was used as base support. It was applicable for the flexible detection and analysis of remote targets. 8 certified reference materials of alloy steel were used as the experimental subject. The spectral acquisition was carried out under the condition of 2 m. 3 elements in certified reference materials, including Si, Mo and Cr, were quantitatively analyzed. The quantitative models of 3 elements were established by random forest (RF) algorithm, and the coefficients of determination were 0.999 8, 0.998 8 and 0.999 1, respectively. During the model validation, the minimum relative errors of predicted contents of 3 elements (Si, Mo and Cr) in validation samples were 14.6%, 12.9% and 11.6%, respectively. The developed miniaturized remote laser-induced breakdown spectroscopy instrument showed good remote quantitative detection capability.

Accurate prediction of bolt fatigue life is very important to guarantee the engineering safety and draw up the maintenance plan. Paris formula is a model which is widely accepted in fatigue analysis. The importance of Paris formula in fatigue life calculation was discussed by analyzing the fatigue fracture of 10.9-grade bolts for pressure vessel. Moreover, the accuracy of Paris formula in failure prediction was also verified. The chemical element analysis, metallographic structure analysis and electron microscopy observation were conducted. The fatigue bands were measured and the data fitting of fatigue band width was performed for the inversion of the fatigue life of two bolt fracture. The results indicated that the crack propagation life of #1 bolt and 2# bolt were 17 251 cycles and 19 549 cycles, respectively. The finite element model verification results showed that the crack propagation life of #1 bolt and 2# bolt were 16 228 cycles and 18 525 cycles, respectively, which were in good agreement with the proposed data. The relative error of fatigue life between the analogue simulation and calculation result were not more than 6%. It was indicated that Paris formula could be used for the accurate prediction of bolt failure under certain conditions, and it provided reliable reference for the improvement of structural part safety.

At present, the determination of tantalum pentoxide and niobium pentoxide in tantalum-iron and niobium-iron concentrate usually adopts gravimetric method, while the determination of titanium dioxide adopts diantipyrylmethane spectrophotometry or inductively coupled plasma atomic emission spectrometry (ICP-AES). However, these determination methods have long operation procedures, and the sample cannot be determined simultaneously in once sample preparation, which hardly meet the requirements of detection efficiency. In this study, the determination method of tantalum pentoxide, niobium pentoxide and titanium dioxide in tantalum-iron and niobium-iron concentrates by wavelength dispersive X-ray fluorescence spectrometry (WDXRF) with fusion sample preparation was established. The working parameters of the instrument were optimized by experiments, and the melting temperature and time were studied. It was found that the optimal melting temperature and time were 1 100 ℃ and 10 min, respectively. The fluidity of melt flow good, the test piece was uniform without non-melt. In addition, the effects of internal standard correction and direct determination on the linear correlation coefficient of the calibration curve were compared. The results showed that the linear correlation coefficient of the calibration curve of tantalum pentoxide was significantly improved after correction with hafnium dioxide. There was no significant difference in the linear correlation coefficient of the calibration curve using internal standard and direct determination for niobium pentoxide and titanium dioxide. The contents of tantalum pentoxide, niobium pentoxide and titanium dioxide in three tantalum-iron and niobium-iron concentrate samples were determined according to the experimental method. The relative standard deviations (RSD, n=9) of determination results were less than 3%. The components of tantalum-iron and niobium-iron concentrate samples were determined by this method and the chemical wet method, and there was no significant difference in the results.

To enhance the development and utilization of metal materials, the precise control of physical properties and mechanical performance of metal materials is crucial, wherein the hydrogen plays a particularly key role in influencing these aspects. In this paper, the impact and hazards of hydrogen on the performance of metal materials were summarized. The methods for determining hydrogen content in metal materials in recent years were introduced, mainly including physicochemical method, tube furnace heating-thermal conductivity/infrared method, inert gas protection pulse furnace heating-thermal conductivity/infrared method, inert gas protection pulse furnace heating-mass spectrometry method, thermal desorption-mass spectrometry method, etc. The corresponding analysis principles, instrument structures, and technical characteristics were summarized. The review of applicable detection objects, analysis range, detection limits, and other specifications could enable the technicians in relevant fields to have a comprehensive understanding of hydrogen content detection in metal materials.

The chemical composition of refined slag in iron and steel metallurgical enterprises is generally determined by X-ray fluorescence spectrometry (XRF). Although there are national standard methods for reference, the analysis speed cannot meet the production requirements in front of the smelting furnace. In this study, the sample was prepared by pressed powder pellet method. The grinding time was 40 s, the pressure was 40 MPa, and the holding time was 40 s. Eight self-made refined slag samples were selected as calibration samples to establish the calibration curve. The method for determination of eight major components in refined slag, including silicon dioxide, aluminum oxide, calcium oxide, magnesium oxide, phosphorus pentoxide, manganese oxide, titanium dioxide, and iron, was established by XRF with pressed powder pellet sample preparation. The linear correlation coefficients of calibration curves of components were all greater than 0.98. The contents of silicon dioxide, aluminum oxide, calcium oxide, magnesium oxide, phosphorus pentoxide, manganese oxide, titanium dioxide, and iron in the refined slag sample were determined according to the experimental method. The relative standard deviations (RSD, n=11) of determination results were all less than 0.06%. Three refined slag samples were determined according to the experimental method, and the measured results were consistent with those obtained by the chemical wet methods (where, the content of silicon dioxide was determined by perchloric acid dehydration gravimetry-silicon molybdenum blue spectrophotometry; the contents of aluminum oxide and calcium oxide were determined by EDTA titration; the contents of magnesium oxide, phosphorus pentoxide, manganese oxide, titanium dioxide, and iron were analyzed by inductively coupled plasma atomic emission spectrometry).

Rare metal ores are often associated with various dispersed metal elements such as zirconium, hafnium, uranium, thorium, thallium, gallium, tungsten and tin. However, there are few literatures on the related testing methods, and the existing rare metal ore reference materials also are in lack of certified values for associated elements such as zirconium, hafnium, gallium, thallium, uranium, and thorium. In this study, six types of rare metal ore reference materials were digested with nitric acid-hydrofluoric acid system with high pressure closed digestion. The residue was redissolved with aqua regia (1+1). The determination of zirconium, hafnium, gallium, thallium, uranium and thorium by inductively coupled plasma mass spectrometry (ICP-MS) was realized. The reference values of six associated elements in six rare metal ore reference materials were provided. The digestion effects of rare metal ore reference materials by three methods, namely open digestion with nitric acid-hydrofluoric acid-perchloric acid, open digestion with nitric acid-hydrochloric acid-hydrofluoric acid-perchloric acid, and closed digestion with nitric acid-hydrofluoric acid, were compared. The results showed that the sample could be completely digested by the high pressure closed digestion method. The rare metal ore reference materials were selected to investigate the redissolution effect by aqua regia (1+1). The results showed that the measurement values of zirconium and hafnium after redissolution with aqua regia (1+1) were consistent with those obtained by alkali fusion-ICP-MS and X-ray fluorescence spectrometry (XRF). It indicated that the hydrolysis problem of zirconium and hafnium could be solved using the oxidability of nitric acid and complexation effect of chlorine ion. The linear correlation coefficients of calibration curves of elements in this method were all higher than 0.999 9. The limit of detection and limit of quantification were 0.01-0.04 μg/g and 0.04-0.16 μg/g, respectively. The proposed method was applied for the determination of elements in certified reference materials GBW07103 (granite), GBW07832 (dispersed element ore), GBW07834 (dispersed element ore) and GBW04132 (sandstone uranium ore) with similar matrix and contents of testing elements. The relative standard deviations (RSD, n=8) of determination results were between 1.5% and 6.4%, which could meet the requirements in DZ/T 0130-2006 The specification of testing quality management for geological laboratories. The measurement results were basically consistent with the certified values of reference materials, and the relative errors (RE) were between -2.6% and 3.2%. The contents of zirconium, hafnium, gallium, thallium, uranium, and thorium in reference materials of rare metal ore (GBW07152-GBW07155, GBW07184 and GBW07185) were determined according to the experimental method, and the reference values of elements were provided. These data could be used as a reference for other studies and provided a foundation for further collaborative study and other work.

With the development of new technologies,some novel ferroboron alloys with different properties are developed.The contents of different elements in ferroboron determines the properties of alloys.At present,the alkali melting method or acid dissolution slag method is usually used for pretreatment of ferroboron sample before detection of elements.Although the sample can be dissolved completely and the simultaneous determination can be achieved,these methods are cumbersome if some elements are determined separately.Therefore,it is very important to choose the appropriate decomposition method for different elements in consideration of the perspective of economy and time cost.In this study,the certified reference materials(CRM) of ferroboron were digested using various decomposition methods including direct acid dissolution method(nitric acid+hydrofluoric acid+perchloric acid),microwave digestion method,acid dissolution slag method and alkali melting method.Then, the contents of chromium,nickel,vanadium,copper,titanium,manganese,aluminum and phosphorus in the digestion solution using different decomposition methods were determined by inductively coupled plasma atomic emission spectrometry(ICP-AES).The results showed that there were few black insoluble matters in the solution when the direct acid dissolution and microwave digestion were used,but the accurate determination of chromium,nickel,vanadium,copper,titanium and manganese was not affected.However,the determination results of aluminum and phosphorus were relatively lower than the certified values or standard values,especially for phosphorus.It indicated that the degree of dissolution of the sample had significant influence on the accurate determination of aluminum and phosphorus.Therefore,for the determination of chromium,nickel,vanadium,copper,titanium and manganese,the four dissolution methods above were all acceptable.However,for the determination of aluminum and phosphorus,the sample must be completely dissolved using acid dissolution slag method and alkali melting method to obtain accurate results.

The accurate determination of titanium carbide content in titanium carbide slag(titanium carbide) plays a key role in the guidance of carbonization production process.In this study,the hydrochloric acid-sulfuric acid-hydrofluoric acid system was used to selectively dissolve titanium oxide,realizing the rapid separation of titanium oxide and titanium carbide phases in titanium carbide slag.After separation,the residue and filter paper were ashed and burned at 600-700 ℃ for 20 min,and then burned at 1 100 ℃ for 2-3 min.Lithium tetraborate-lithium carbonate was selected as the flux,and lithium bromide was selected as the release agent.The sample was fused at 1 100 ℃ for 20 min to prepare the transparent bead.A method for the determination of titanium carbide in titanium carbide slag by X-ray fluorescence spectrometry with fusion sample preparation was established.After the titanium carbide slag sample was separated using the hydrochloric acid-sulfuric acid-hydrofluoric acid system,titanium carbide in the residue could be converted to titanium dioxide through burning at high temperature.Therefore,nine samples of spectrally pure titanium dioxide(5.0-80.0 mg) were used to draw the calibration curve.The linear correlation coefficient was r=0.999 98,and the determination range of titanium dioxide was 1.25%-20.0%.The contents of titanium carbide in two titanium carbide slag samples were determined according to the experimental method,and the relative standard deviations(RSD,n=6) of the determination results were not more than 0.5%.Three titanium carbide slag samples were selected and determined according to the experimental method.Then the high-purity titanium carbide was added for the spiked recovery test.The recoveries were between 97% and 102%.The contents of titanium carbide in titanium carbide slag samples were determined by the experimental method and spectrophotometry respectively,and the results were consistent.

It is of great significance to determine chromium (Ⅵ) accurately in site soil for the management and remediation of contaminated site. Alkali solution extraction-flame atomic absorption spectrometry is one of the main analysis methods for determination of chromium (Ⅵ) in site soil. The certified reference materials and actual samples of site soil were used as research object, and the effects of heating method, stirring speed, liquid-solid ratio and reducing remediation reagent on the determination of chromium (Ⅵ) were investigated. The results showed that the extraction of chromium (Ⅵ) in site soil was more complete when the water bath heating was used, and the stability of determination results were better than that of electrical heating. The stirring rate could significantly affect the determination results of chromium (Ⅵ), and the continuous and steady medium speed stirring showed best effect. Under normal conditions, the liquid-solid ratio of 10∶1 could satisfy the effective extraction of chromium (Ⅵ) in conventional soil samples. However, for the site soil samples with chromium (Ⅵ) content exceeding the upper limit of linear range of calibration curve, the optimal liquid-solid ratio should be obtained by reducing sample mass to ensure the accuracy and reliability of determination results. The reducing remediation reagent had negative interference with the standard addition tests of chromium (Ⅵ). Hydrogen peroxide was added before extraction followed by ultrasonic reaction at room temperature for 5 min. It could change the reducing properties of sample matrix, and meanwhile, keep the chemical form stability of chromium (Ⅵ) in soil sample. The spiked recoveries of chromium (Ⅵ) increased to 75.0%-97.5%. Therefore, the interference of reducing remediation reagent with the spiked recovery test of chromium (Ⅵ) could be effectively eliminated.

Large non-deformable inclusions are one of the main causes of wire breakage for tire cord steels during drawing and stranding.Therefore,it is necessary to study the types and evolution law of inclusions in the tire cord steel.In the paper,the type and morphological evolution law of inclusions in 82A tire cord steel from billet to wire rod were investigated by the means of focused ion beam-electron beam scanning electron microscopy(FIB-SEM),energy disperse spectroscopy(EDS) and three-dimensional reconstruction software.The results showed that the main types of inclusions were MnS,MnS-SiO₂ and MnS-SiO₂-CaMgAlMnSiO.The planar morphology of MnS inclusions in the billet were mostly elliptical or nearly round,while the morphology of MnS in the wire rod became elongated strip shape.The planar morphology of MnS-SiO₂ inclusions in the billet had the core of nearly round SiO₂, and the outer layer was wrapped MnS.In the wire rod,its morphology was still maintained in the nearly round SiO₂ as the core,but the MnS wrapped on outer layer became long stripes,showing the overall appearance of "eye-shaped".The planar morphology of MnS-SiO₂-CaMgAlMnSiO inclusions in the billet was based on SiO₂ as the core,which was wrapped with composite oxides enriched in Ca,Mg,Al,Mn,Si and O,and the outermost layer was MnS.In wire rod,the deformation of SiO₂ was not obvious,and composite oxides became fragmented. Moreover,MnS was elongated,and the whole morphology showed string-like distribution along the drawing direction.The study on the evolution law of inclusions type and morphology provided process control direction for the analysis of inclusions harm and the development of high-end tire cord steel.