High-temperature Metallurgy Research Articles

Design and performance characterization of highly wettable core-shell structured SiC@C composites

SiC@C composites are extensively used in high-temperature metallurgy owing to their distinctive physicochemical properties. In this study, SiC@C composites with a core-shell structure were synthesized using silicon powder and Fe2O3 as the silicon source and catalyst, respectively. The effect of various temperatures on the synthesis of the SiC@C composites was investigated. The results indicated that a SiC whiskers layer covers the graphite surface at 1600 °C. At this temperature, the production of silicon carbide reaches 9.2 %. Transmission electron microscope (TEM) revealed that the preferred growth orientation of SiC was the (111) crystal plane. Based on density functional theory, the adsorption properties of different crystal planes of SiC crystals and their interactions with Fe atoms on the crystal surface were investigated. The results showed that the adsorption properties of different SiC crystal planes varied, with the (111) crystal plane exhibiting the strongest adsorption ability. In the presence of Fe atoms, the adsorption properties of the (111) crystal plane reaches to a value of −2686.5253 Ha, indicating that Fe atoms can promote the adsorption of other atoms or molecules on the surface of SiC crystals. Additionally, the wettability of the SiC@C composites was improved, as evidenced by the decrease in the contact angle from 109° to 46°.

Hydrogen dioxide-boosted acid elution of radionuclides from high level vitrified wastes

• A wet chemical elution was used to extract radionuclides from nuclear waste glass. • H 2 O 2 largely enhanced the elution capability of HNO 3 under mild conditions. • The insoluble Zr was well extracted by H 2 SO 4 solution through coordination. • The PGMs were extracted using liquid Sn extraction under reductive heat-treatment. The extraction of radionuclides from high-level vitrified wastes (HLVWs) is of importance for eventual harmlessization of nuclear wastes by nuclear transmutation, but remains great challenges. Here, we showed an efficient elution method of various radionuclides from the simulated HLVWs with chemical durability using the mixed H 2 O 2 /HNO 3 solutions under mild conditions. The introduction of H 2 O 2 largely improved the elution capability of HNO 3 solution toward radionuclides contained in HLVWs. Most elements including glass main components (except the insoluble Si) and the simulated radionuclides (except for Zr and platinum group metals (PGMs: Pd, Ru, Rh)) were significantly leached from the HLVWs with the mixed solution of 1 ml H 2 O 2 /1 M HNO 3 at 90 °C for 5 h. The insoluble Zr and PGMs were further extracted by H 2 SO 4 solution and liquid tin extraction, respectively. Through optimization of the extraction conditions, the proposed wet chemical elution method and high temperature metallurgy to extract the elements from the HLVWs would open a new avenue to reduce the radioactivity and lifetime of the long-lived fission products (LLFPs) and minor actinides (MAs) in HLVWs through advanced nuclear transmutation in future. It also provides a feasible method for the reuse of some valuable radionuclides in HLVWs.

A Blast Furnace Burden Surface Deeplearning Detection System Based on Radar Spectrum Restructured by Entropy Weight

Accurately capturing the burden surface information of a blast furnace (BF) is helpful to adjust the burden distribution matrix and improve the gas flow distribution, which is essential in the steel smelting industry. However, it is difficult to detect the burden surface because of the high temperature, high pressure, high dust and flame combustion environment condition inside the BF, in addition to the fluidization characteristics of the burden surface. With the fusion of high-temperature metallurgy, radar detection and image processing, a new BF surface deep-learning detection system based on energy weight was developed in this study to visualize the smelting status of a BF and digitize the information of the burden surface. First, the original burden surface echo spectrogram was captured using a frequency-modulated continuous wave radar with a high-temperature-resistant sensor. Second, the point cloud distribution map was constructed based on the principle of synthetic aperture radar (SAR) imaging. The coordinate transformation and matrix compensation were completed by the entropy weight method and Gamma correction to convert point cloud map to the burden surface grayscale image, constructing datasets for the network. Third, with a 3rd-order hourglass feature extraction network, a BF surface detection network based on the principle of YOLOv3 was designed and trained to predict the position of the burden surface in the grayscale image and track the changing trend of the burden line. The proposed method, which is tested on two steel plant datasets, achieved an average prediction precision of 99.74%. Finally, compared with the traditional burden line extraction algorithm, burden line oscillations and local outliers can be avoided by the proposed method. The continuous detection of the BF surface information was realized.

Sources of atmospheric lead (Pb) in and around an Indian megacity

Lead (Pb) is a toxic metal whose global anthropogenic fluxes are an order of magnitude higher than natural fluxes. Among all the environmental compartments, the atmosphere is the major initial recipient of Pb. To minimize the exposure to this toxic metal, it is important to determine the potential sources of atmospheric Pb. This study uses a multiproxy approach, Pb isotopes in conjunction with metal composition of aerosols to determine the possible sources of anthropogenic Pb in the atmosphere, in and around an Indian megacity, Kolkata. In Asia, India is the second largest atmospheric Pb emitter after China through coal combustion. Indian automobile and high temperature metallurgy industries are growing rapidly and Pb emissions from India can be traced as far south as in Chagos Island in the Indian Ocean. This study investigates the anthropogenic sources of atmospheric Pb in eastern India at three locations along a 150 Km N-S stretch. The locations have very different environmental settings; a pristine river island, a megacity, and an industrial town. Pb isotope and metal compositions indicate different sources of atmospheric Pb for the three locations: gasoline exhaust from road and riverine traffic in the island, emissions from the high temperature metallurgy industry in the industrial town and long-range transport of coal combustion and industrial emissions for the megacity. The Pb isotope ratios (206Pb/207Pb = 1.1155–1.1681 and 208Pb/207Pb = 2.3905–2.4494) measured in this study have a wider range and are mostly higher than previously measured in Indian aerosols. Pb isotope compositions of two end members, Indian coal and road dust are also measured. This study shows that post leaded gasoline phase-out, the atmospheric Pb emissions in India are dominated by Indian coal combustion and ore processing.

高温冶金反応を利用した廃棄物の処理･再資源化技術

高温冶金反応を利用した廃棄物の処理･再資源化技術

Gasification and smelting system using oxygen blowing for plastic waste including polyvinyl chloride

A new type of waste gasification and smelting system using oxygen blowing based on high-temperature metallurgy, was developed by Sumitomo Metals, Japan. This system can steadily gasify and melt not only municipal waste, but also plastic waste and polyvinyl chloride (PVC) waste by using a top-blow oxygen lance together with sideways-blow oxygen lances. As a result of gasification in the high-temperature reducing atmosphere and rapid gas cooling, dioxin-free, high-calorie purified gas was produced. Ash components in the wastes were smelted in a high-temperature reducing atmosphere, and high-quality slag free of heavy metals was produced. Most of the chlorine in the wastes was converted into hydrogen chloride in the off gas. The hydrogen chloride can be recovered as hydrochloric acid or chlorine, which are recyclable to PVC manufacturing.

High-temperature metallurgy of advanced borated stainless steels

The high-temperature metallurgy of advanced borated stainless steels has been evaluated through differential thermal analysis, aging studies, quantitative metallography, and impact toughness measurements. Differential thermal analysis (DTA) was conducted on alloys containing a range of boron concentrations and was used to determine the temperatures associated with melting/ solidification reactions. Aging studies, conducted at temperatures near the solidus, were used to determine the effects of elevated temperature exposures on impact properties and micro-structure. Differential thermal analysis quantified the solidus and liquidus temperatures as a function of boron concentration. Impact testing of samples aged at temperatures near the solidus indicated only moderate reductions in toughness. Particle shape measurements indicated that the boride particles were initially nearly spherical and remained so during elevated temperature exposure, although some faceting and agglomeration of the borides did occur. Measurements of boride particle size distributions were used to define the time, temperature, and composition dependence of the boride coarsening. Coarsening data were analyzed in terms of current coars-ening models. These analyses indicated that the boride particle coarsening followed the theo-retically predictedt1/3 time dependence and that the coarsening rate increased with increasing volume fraction of the boride phase. Analysis of the particle size data for aging at various temperatures indicated that the boride coarsening was consistent with the activation energy for Cr diffusion in austenite. Scanning electron microscopy of the impact fracture surfaces showed that the failure mode in isothermally heat-treated samples was ductile and essentially identical to the failure mode for as-received material.

The Effect of Sea‐Water Velocity on the Corrosion Behavior of Metals

Naval Engineers JournalVolume 78, Issue 5 p. 763-769 The Effect of Sea-Water Velocity on the Corrosion Behavior of Metals G. J. DANEK JR., G. J. DANEK JR. The Author is a Senior Project Engineer, Naval Alloys Division, U. S. Navy Marine Engineering Laboratory, Annapolis, Maryland. He received his Bachelor of Science degree in Chemistry from Loyola College, Baltimore, Maryland, in 1950. Subsequently, he acquired training in Metallurgy at U. S. Naval Postgraduate School, University of Maryland, and Johns Hopkins University. The author's professional experience includes teaching at the Naval Postgraduate School, research in high-temperature metallurgy at Naval Research Laboratory, and corrosion research at the U. S. Navy Marine Engineering Laboratory.Search for more papers by this author G. J. DANEK JR., G. J. DANEK JR. The Author is a Senior Project Engineer, Naval Alloys Division, U. S. Navy Marine Engineering Laboratory, Annapolis, Maryland. He received his Bachelor of Science degree in Chemistry from Loyola College, Baltimore, Maryland, in 1950. Subsequently, he acquired training in Metallurgy at U. S. Naval Postgraduate School, University of Maryland, and Johns Hopkins University. The author's professional experience includes teaching at the Naval Postgraduate School, research in high-temperature metallurgy at Naval Research Laboratory, and corrosion research at the U. S. Navy Marine Engineering Laboratory.Search for more papers by this author First published: October 1966 https://doi.org/10.1111/j.1559-3584.1966.tb04144.xCitations: 36 AboutPDF ToolsExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume78, Issue5October 1966Pages 763-769 RelatedInformation