Boron In Iron Research Articles

Структура и свойства низкоуглеродистой стали после плазменной наплавки борсодержащей обмазки

Introduction. One of the effective thermochemical methods for increasing the hardness of steel is boronizing by diffusion of boron atoms into the steel surface at high temperatures. As a result of boronizing, coatings are formed on the steel surface, consisting of columnar crystals of FeB and Fe2B. The volume fraction of phases and the thickness of the coatings depend on the heating temperature and the chemical composition of the base material and the saturating medium. The main disadvantage of these boronized layers is its high brittleness. Boronizing by plasma heating is one of the alternatives to the diffusion boronizing process to minimize the brittleness of the boronized layer. The purpose of the work: to form boride coatings on low-carbon steel using plasma-jet hard-facing. The research methods are: determination of the content of chemical elements using an electron probe micro-analyzer, metallographic studies, analysis of the phase composition of the boronized layer, as well as measurement of the microhardness of the coating after plasma-jet hard-facing. In this work boronized layers obtained on low-carbon steel 20 by plasma-jet hard-facing of a boron-containing coating are studied. Powdered amorphous boron was used as an alloying element. The parameter varied during plasma-jet hard-facing process is the current strength (120 A, 140 A and 160 A). Results and discussions. Based on the studies performed, it is found that it is possible to form boronized layers on the steel surface using plasma-jet hard-facing method. It is noted that the surface layer of the coating of the 1st and 2nd specimens after plasma-jet hard-facing has a heterogeneous structure, consisting of rows of different zones. The first zone has a hypereutectic structure, which consists of primary borides FeB and Fe2B, located in the eutectic, consisting of Fe2B and α-Fe. The second zone above the boundary with the base metal is represented by eutectic colonies composed of Fe2B and α-Fe. The third specimen is characterized by a hypoeutectic structure consisting of boride eutectic and primary dendrites of the α-solid solution of boron in iron. The maximum hardness is fixed on the surface of the first specimen and is 1,575 HV. The depth of the hardened layer increases with increasing current, but the hardness value and boron content decrease after treatment. The slight hardness gradient observed over the depth of the coating, as well as the gradual decrease in hardness due to the presence of the transition zone, are considered favorable for good adhesion of the boronized layer to the surface of the base material.

A Study of the Properties and Structure of Rolling-Mill Iron Modified with Boron

The effect of boron additions on the properties and structure of rolling mill iron is studied. The composition of boride phase and carbides, and also the ratio of structural components in iron with different boron contents are determined. Structural transformations in iron during heat treatment are studied by differential thermal analysis and differential scanning calorimetry. The optimum concentration of boron in iron for improving its properties is determined.

A Contribution to the Understanding of the Combined Effect of Nitrogen and Boron in Grey Cast Iron

Inoculation is an essential part of controlling material properties in grey cast iron. Inoculation practice has for decades been based on the addition to the melt of small amounts of elements with a strong affinity to O (and S) just before casting takes place. This method is proven—both in theory and in practice—to be effective in most cases. But it has the disadvantage that the nucleation effect fades away over time. In particular, in heavy castings (slow cooling) this effect may cause non-uniform and unacceptable material properties in some parts of the casting. Nitrogen is also known to influence grey iron microstructure. Both graphite flake formation and matrix formation are influenced. However, the obtained effects differ considerably between different reported investigations. This investigation deals with the combined effect of nitrogen and boron and how it is possible to utilize this effect to enhance material properties in heavy grey iron castings. It is shown that the controlled additions of nitrogen and boron can be used to control the microstructure of thick section grey iron castings. A plausible theory for the formation of boron nitride nuclei effective for graphite growth is presented.

Theoretical Investigation of Stabilizing Mechanism by Boron in Body-Centered Cubic Iron Through (Fe,Cr)23(C,B)6 Precipitates

Small amounts of boron improve the mechanical properties in high-chromium ferritic heat-resistant steels. In this work, the stabilizing mechanism by boron in body-centered cubic iron (bcc Fe) through (Fe,Cr)23(C,B)6 precipitates was investigated by first-principles calculations. Formation energy analysis of (Fe,Cr)23(C,B)6 reveals that the compounds become more stable to elemental solids as the boron concentration increases. Furthermore, the interface energy of bcc Fe(110) || Fe23(C,B)6(111) also decreases with boron concentration in the compounds. The decreased interface energy caused by boron addition is explained by the balance between the change in the phase stability of the precipitates and the change in the misfit parameter for the bcc Fe matrix and the precipitates. These results show that boron stabilizes the microstructure of heat-resistant steels, which is important for understanding the origins of the creep strength in ferritic steels.

Boron effect on the precipitation of secondary carbides during destabilization of a high-chromium white iron

This work analyses the secondary carbides precipitation during the destabilization of a 17% Cr White iron containing 195 ppm boron. The experimental iron was characterised in the as-cast conditions to have comparable parameters with the heat-treated samples. Destabilisation heat treatments were undertaken at temperatures of 825, 900 and 975 °C for 25 min; each sample was air-cooled after this soaking time. Characterisation was undertaken by optical and electronic microscopy, image analysis and energy dispersive spectroscopy microanalysis, hardness and microhardness were also evaluated. It was found that the volume fraction of secondary carbides precipitated is always higher for the lowest destabilisation temperature (825 °C) due to the lower carbon solubility in austenite at low temperatures. A much higher precipitation for the irons containing boron than that for the iron without boron at any destabilisation temperature was also noticed. For the iron containing boron, a density of 23 carbide particles per square micron was measured when destabilised at 825 °C, and it decreased to about 10 particles per square micron when destabilised at 975 °C. In the case of the alloy without boron additions, about 10 carbides per square micron were counted when destabilised at 825 °C and about 5 when destabilised at 975 °C. Higher volumes of carbides precipitation implies higher values of bulk hardness and microhardness in the alloys. The results suggest that boron works as a nucleant for the precipitation of secondary carbides; this is discussed in terms of the limited solubility of boron in iron and the formation of boron-rich precipitates found in the iron in the as-cast conditions.

Determination of Boron in Steel and Iron Using Standard Addition Method

Determination of Boron in Steel and Iron Using Standard Addition Method

Effect of boron addition on the microstructure and mechanical properties of 6.5% V-5% W high speed steel

The effect of adding 0.04% additional boron to 6.5% V-5% W high speed steel was investigated. The microstructure characterization, phase identification, and carbide identification of the materials were performed using SEM/EDS and XRD. The cell size and carbide volume fraction were examined using image analysis software. The boron distribution was observed by PTA Boron Tracking. The addition of 0.04% more boron to a HSS alloy exerted a cell refining effect on the sample. The cell refinement of dendritic structures in the alloy containing boron may be attributed to the constitutional supercooling effect associated with the fairly small distribution coefficient for boron in iron. The addition of boron increases the bending strength of the material by more than 10%, as well as increasing its hardness.

The Equilibrium Relation of Immiscibility in an Fe-Cu-B System at 1873 K

The equilibrium relation of the phase separation in the Fe-Cu-B system is investigated at 1873 K for potential use in the separation of copper from iron in steel scrap recycling. Liquid immiscibility is confirmed even at low boron content in iron, [mass%B] (in Fe) = 0.006. By combining the Taylor series equation proposed by Wagner and that of the quadratic formalism proposed by Darken, the thermodynamic interaction parameters of copper for boron in molten iron, which can be applied with precision over the wide concentration range, are derived. The first and the second order interaction parameters of copper for boron in molten iron at 1873 K are: e B Cu = ―ρ Cu,B Cu = 12.1(±0.6),ρ B Cu = ―18.9(±11.0) (N B(in Fe) < 0 .34) e B Cu = 0.254(±0.014), r B Cu = ―0.032(±0.014) ([mass%B] (in Fe) < 8.9) Moreover, the immiscibility range in the Fe-Cu-B system is also investigated by applying a symmetrical and regular solution model.

TEORES FOLIARES E EXPORTAÇÃO DE NUTRIENTES DO MAMOEIRO BAIXINHO DE SANTA AMÁLIA TRATADO COM BIOFERTILIZANTES

Papaya tree is a crop with expressive economic importance in Brazil, where it has been traditionally cultivated with mineral soil fertilizing, although, for the last two decades, the world market has required lower levels of synthetic products use for food production and higher levels of the natural ones. In this way, one experiment was carried out in Remígio, Paraíba State, Brazil, to evaluate the leaf nutrient status, at the beginning of the blooming stage, and the exportation of sodium, macro, and micronutrients of the “Baixinho de Santa Amália” papaya cultivar. A complete randomized blocks experimental design was used in a 2x5 factorial arrangement, referring to pure biofertilizer and biofertilizer enriched with sodium, macro, and micronutrients, under 0.0 L plant-1; 0.5 L plant-1; 1.0 L plant-1; 1.5 L plant-1; and 2.0 L plant-1 doses, applied to soil under their liquid form. The enriched biofertilizer was more efficient, in relation to the pure one, for leaf nutrient status and nutrient exportation of papaya fruit, for all doses applied to soil. At the beginning of the blooming stage, all plants were adequately supplied with nitrogen, potassium, sulfur, boron, cooper, and zinc, but deficient in phosphorus, calcium, magnesium, iron, and manganese. The most exported nutrients were potassium, among the macronutrients, and iron, among the micronutrients. KEY-WORDS: Carica papaya L.; biofertilizer; mineral status.

Determination of Trace Boron in Iron and Steel by Adsorptive Stripping Voltammetry using Beryllon III

Adsorptive stripping voltammetry is proposed for determination of boron at low μg g−1 level in iron and steel. Beryllon III was used as a complexing agent for boron(III). Optimum conditions for the formation of the boron(III)–Beryllon III complex were as follows: 0.06 M nitrate–0.04 M sulfate supporting electrolyte at pH 4.5; 1.0×10−5 M Beryllon III; 24 h complexation time. The complex was accumulated on a hanging mercury drop electrode at −0.35 V vs. SCE for 60 s under stirring, and was subsequently cathodically stripped to −0.8 V vs. SCE at a scan rate of 10 mV s−1 using a differential pulse mode. Interference by iron(III) was eliminated by the complexation with metaphosphoric acid. After cathodic stripping, a single well-defined peak was observed at around −0.5 V vs. SCE. The influence of foreign elements on the determination was also evaluated. The calibration graph (peak height vs. boron(III) concentration) in the presence of 1 mg mL−1 iron(III) was linear over a concentration range of 1–25 ng mL−1 (correlation coefficient >0.999), with a relative standard deviation (n=4) of 2.6% at 10 ng mL−1. The minimum limit of determination was 1 μg g−1 of boron in iron and steel. The proposed method has been proved to be applicable to the determination of trace boron in iron and steel with good precision and accuracy.

The combined role of nickel and boron on the nucleation and growth of Fe-based non-crystalline alloys

Amorphous ribbons of composition Fe 75− x Ni x Si 9B 16 ( x = 1 , 2, 3, 4) were in situ crystallized upon heat treatment and electron beam irradiation. Depending on the Ni concentration an eutectic or primary crystallization took place. The sequence of phases formation was followed by transmission electron microscopy observations and thermal analysis. Other studies (Scripta Metall. 12 (1978) 75, Appl. Phys. Lett. 33 (1978) 233, RQ 111, 1 (1978) 44428) led to the conclusion that the presence of a supersaturated solid solution of boron in Fe-based amorphous alloys strongly influences the crystallization process. In our case, the onset crystallization is determined by the boron solid solution in iron in the case of Ni content less than 3 wt%, while Ni admixtures more than 4 wt% alter the process of the nucleation and the subsequent crystallization. The last one results in the formation of an ultrafine grain structure composed mainly of α-Fe(Si) crystallites. It seems that the modification of the crystallization is a result of the inhibition of the formation of a supersaturated solid solution of boron in iron. An observed large scattering of the values of the lattice parameter of α-Fe(Si) crystallites was ascribed to a different degree of occupation of metalloid atoms in the α-Fe grains.

The Solubility of Nitrogen and Nitrides in Ternary Liquid Iron Alloys. The Limits of the 'Solubility Product' Concept

The associated mixture model has been applied to describe equilibria in the Fe-rich corner of two ternary Fe-X-N system (with X = Al or B). It has been found that at 1873 K more than 90 % of nitrogen is complexed into AlN molecules (associates) in the Fe-Al-N system, when the molar ratio of aluminum to nitrogen is higher than 2.5. On the other hand, in the Fe-B-N system 37 % of boron is complexed into BN molecules (associates) at 1823 K, when the nitrogen content of the melt is above 80 ppm, and the boron content of the melt is below 60 ppm. The phase boundaries between liquid iron and N2 gas on the one hand, and between liquid iron and solid AlN and BN phases on the other hand have been determined. The of N2 gas increases with increasing concentration of aluminum and boron in the liquid iron. The concentration dependence of the of AlN and BN considerably differs from that predicted by the concept of the solubility product, due to the strong complex (AlN and BN) formation in the systems.

Determination of Trace Amounts of Antimony and Boron in High-Purity Iron and Steel by Isotope Dilution/Inductively Coupled Plasma Mass Spectrometry

The highly sensitive and precise determination method for trace amounts of Sb and B in high-purity iron and steel has been established by the isotope dilution/Inductively coupled plasma mass spectrometry. For the determination of Sb, the iron matrix was separated by anion-exchange chromatography using Dowex I-X8 in hydrofluoric acid solution, and the isotope ratio ( 121 Sb/ 123 Sb) of the HNO 3 /H 2 O 2 eluate was measured by ICP-MS. The isobaric interference of 123 Te was corrected by subtracting the intensity of 123 Te obtained by the relative intensity of 123 Te and 125 Te. For the determination of B, after the treatment of sulfuric acid-phosphoric acid fuming for the complete decomposition of boron nitride, B was separated by the anion-exchange chromatography using Amberlite IRA-743 at pH 8. The CyDTA was added to prevent the hydrolysis of iron. The isotope ratio ( 11 B/ 10 B) of the HCI eluate was measured by ICP-MS. By these methods, Sb and B in the range of μg/g to sub-μg/g could be determined with good precision. The limit of detection is 5.8 ng/g for Sb and 16 ng/g for B in steel.

Continuous flow system for the determination of trace boron in iron and steel utilizing in-line preconcentration/separation by Sephadex column coupled with fluorimetric detection

A simple, rapid and sensitive system for the determination of trace boron in iron and steels is presented, in which in-line separation/preconcentration of boron from iron matrix is directly coupled with fluorimetric detection in a continuous flow system. Boron was adsorbed on a small column packed with Sephadex G-25 gel, followed by elution with a small volume of dilute hydrochloric acid. The formation of boron complex with 1,8-dihydroxy-3,6-naphthalenedisulphonic acid in a continuous flow system was used for the sensitive determination of boron by fluorescence detection( λ ex=314 nm and λ em=355 nm). The present FIA system offers many advantages over existing methods, especially with respect to simplicity and sensitivity, permitting semi-automated determination of boron with a short analysis time (about 10 min), low limit of determination (0.1 ppm in steels) and good reproducibility (rsd<3% for 1–18 μg g −1 boron in steels).The present FIA system can be readily applied to the steel samples.

高度技術を支える分析化学 自作カラムを用いるイオン対逆相分配高速液体クロマトグラフィーによる鉄及び鋼中の微量ホウ素の直接定量

研究室で充填した自作カラム (4.6mm i.d.×50mm) を用いるイオン対逆相分配高速液体クロマトグラフィーにより, 鉄及び鋼中の微量ホウ素を直接定量した. 自作カラムはスラリー法によりHPLC用ODS (C18) 充填剤 (粒径5μm) 0.7gを充填して作製した. 鉄鋼試料を塩酸-硝酸で分解し, リン酸と硫酸を加えて蒸発乾固した後, 希塩酸に溶解した. この分解溶液から適量を分取し, 7.5×10-3mol dm-3 1,8-ジヒドロキシナフタレン-3,6-ジスルホン酸 (クロモトロープ酸) 溶液2.5cm3, 0.275mol dm-3エチレンジアミン四酢酸二ナトリウム溶液2.5cm3及び0.5mol dm-3臭化オクチルトリメチルアンモニウム溶液を含む1.0mol dm-3酢酸緩衝液 (pH 4.8) 2.5cm3を加えてから水で25cm3に定容とする. この溶液から200mm3を自作カラムを装着した高速液体クロマトグラフに注入する. 溶離液には5.0×10-2mol kg-1臭化オクチルトリメチルアンモニウム, 5.0×10-3mol kg-1リン酸緩衝液 (pH 8.0) を含む水-メタノールの混合溶液(45 : 55w/w) を用いた. 検出波長を350nm, 流量を1.0cm3 min-1としてHPLC測定を行った. ピーク高さに基づく検量線はホウ素濃度が10-8mol dm-3レベルにおいて直線性を示し, 空試験値 (n=5) の標準偏差の3倍と定義した検出限界 (3σ) は1.3×10-9mol dm-3であった. 本法を鉄鋼認証標準物質 (日本鉄鋼連盟) 等に適用し, 保証値あるいは参考値 (0.2～50ppm) とよく一致する定量値を得た.

Spectrophotometric Determination of Trace Amounts of Boron in High-Purity Iron and Ferroalloy after Chemical Separation

It is known that impurity elements in steel and other feeds exert an influence on the material characteristics. It is known that boron has a large influence on hardening and brittleness of iron even if a small amount of pole exists, and is requested a accurate quantitative analysis of with good repeatability. Boron is sensitively determined by spectrophotometry after color development with curcumin. However the blank value is high. Therefore, methanol and acids used for the analysis are refined, water is added in addition after color development, and the blank value has been decreased. As a result, the blank value decreased from 0.35 to 0.05 μg and the detection limit of boron became 0.01 ppm. Then, trace amount of boron in high purity electrolysis iron (mairon HP) became 0.24±0.01 ppm by using this method. The separation of B from the matrix is possible hardly receiving the influence of the coexistence element. However, there are little examples of investigation on the recovery of boron by co-precipitation. Si was selected us an element to check the influence in this report. In addition, application of separation procedure to the Fe-Cr-Si alloy was performed. The decrease at the recovery of boron was admitted that the amount of Si in the solution exceeded 25 mg. Then, the Fe-Cr-Si alloy was taken, in which the amount of Si should not exceed 25 mg, and boron in the alloy was determined As a result, it was possible to measure in the change coefficient (C.V) 3.1%.

Substoichiometric and instrumental/charged particle activation analysis of oxygen, nitrogen, carbon and boron in high-purity iron.

荷電粒子放射化分析による高純度鉄中の酸素,窒素,炭素及びホウ素の定量法を検討した.鉄マトリックスから誘導される放射能の影響を考慮して機器的手法の限界を探り,p衝撃による窒素及びd衝撃による炭素の定量を可能にした.また,機器的手法の適用が困難な酸素及びホウ素について,不足当量分離を用いた化学操作を検討し,0.1ppm台の定量法を開発した.これら方法を用いて,酸素分析用に作製された高純度鉄中の窒素,炭素,酸素及びホウ素の逐次定量を行った.更に簡便法を含む解析法の正確さ,また軽元素の定量に妨害核反応の影響がないことを明らかにした.

Determination of Trace Amounts of Metalloid Elements in High-Purity Iron by Chemical Separation-Spectrophotometry

Boron is sensitively determined by spectrophotometry after color development with curcumin, but, the presence of a large amount of iron interferes with the color development. Therefore, in order to separate boron from the iron, boron is allowed to react with methanol to form trimethyl borate ester which is separated from iron by distillation. The distilled ester is trapped into sodium hydroxide solution. For color development with curcumin, water in the solution must be removed by evaporation. The procedure is time-consuming. In order to shorten the time, an apparatus for the distillation is modified to carry out simultaneously both distillation of the ester and evaporation of water in sodium hydroxide solution which traps it. Hence, the time of these procedures is shortened to 25 min from about 90 min of a conventional procedure. Boron reacted with curcumin is extracted with 4-methyl-2-pentanone. The detection limit of boron in iron corresponds to 0.048 μg/g.

Influence of phosphorus addition on the surface tension of liquid iron and segregation of phosphorus on the surface of Fe-P alloy

This article presents a study of the surface tension and phosphorus surface segregation in Fe-P alloys. The surface tension was measured by the sessile drop technique. The result of the dynamic surface tension for the low phosphorus content alloys shows that the alloy surface vaporization has a clear effect on the surface tension and causes a positive surface tension temperature coefficient. However, from this article, it is evident that phosphorus in liquid iron acts as a surface active element similar to arsenic. The surface segregation was determined using Auger electron spectroscopy. The result on the surface analysis of as-solidified sample indicates that the adsorption of impurity elements, such as oxygen, carbon, and nitrogen, can conceal phosphorus segregation on the free surface. Phosphorus segregation was also examined in the samples as-cleaned by Ar+ and then treated 30 minutes at 650°C. Phosphorus was found to segregate extensively on the surface of the alloys. On the basis of the analysis of the published data, the surface active intensity sequence of some nonmetallic elements was arrayed, and the surface active intensity of fluorine and boron in liquid iron was estimated.

Isotope Dilution Analysis for Flow Injection ICPMS Determination of Microgram per Gram Levels of Boron in Iron and Steel after Matrix Removal

Isotope dilution analysis using flow injection inductively coupled plasma mass spectrometry was applied to determine low boron contents in iron and steel samples. Sample dissolution was carried out in a microwave oven with an HCl, HNO3, and H2SO4 acid mixture and high-pressure digestion vessels. A solvent extraction procedure using acetylacetone−chloroform was applied for the separation of the iron matrix as the sulfate (pH = 1.4 ± 0.1). Test solutions corresponding to 50 mg mL-1 of sample, with the total boron content and iron contents below 1 μg mL-1, were obtained. Flow injection was used as a sampling system to minimize problems arising from the total salt concentration of the test solutions. This method made it possible to analyze boron in iron and steel at submicrogram per gram levels. The detection limit (3σ), in micrograms of boron per gram of sample, was 0.02, and the precision for concentrations above 10 times the detection limit was better than 1%. Accuracy was tested with eight standard refere...