Carbide refinement in M42 high speed steel by rare earth metals and spheroidizing treatment

The influence of rare earth metals and heat treatment on the microstructure and performance of M42 steel has been investigated by means of an optical microscope OM scanning electron microscope SEM energy dispersive spectroscopy EDS transmission electron microscope TEM electron back-scatter diffraction EBSD and X-ray diffraction XRD . The results show that M2 C is the prevailing type of eutectic carbides in M42 steel. After modification with rare earth metals M2 C eutectic carbides change from the ordered lamellar structure into a circular structure.Despite different morphologies the two carbides present the same characteristics of microstructure and growth orientation.Compared with lamellar carbides M2 C carbides with the circular structure are much easier to decompose and spheroidize after heating which remarkably refines the carbide dimensions.The refined carbides improve the supersaturation of alloying elements in martensite and increase the hardness of M42 steel by 1.5 HRC.

EFFECTS OF RARE EARTH METALS ON MICROSTRUCTURAL TRANSFORMATION OF LOW OR MEDIUM CARBON Si-Mn-V STEELS DURING QUENCHING AND TEMPERING

The microstruetural transformation of steels:20SiMn2V,20SiMn2VRE,40SiMn2V and 40SiMn2VRE during quenching and tempering have been examined by TEM,X-ray diffraction and dilatometer.It was shown that the addition of rare earth metals not only can refine the austenite grains of the low or medium carbon steels and packet of lath martensite and lath size,lower the M_s temperature,but can also raise the relative percentage of disloca- tion substructure of martensite in medium carbon steel,but there is little effect on volume frac- tion and thermal stability of retained austenite quenching and tempering structure of low or medium carbon steels.The rare earth metals may remarkably inhibit the decomposition of low carbon martensite during low temperature tempering,retard the precipitation of cementite plates in lath grains and delay the spheroidization of carbides.They may also restrain obvious- ly the precipitation and spheroidization of cementite in medium carbon martensite during high temperature tempering.

Recovery of rare earth metals through biosorption: An overview

Rare earth metals （REMs） are a series of 17 elements that have widespread and unique applications in high technology, power generation, communications, and defense industries. These resources are also pivotal to emergent sustainable energy and car- bon alternative technologies. Recovery of REMs is interesting due to its high market prices along with various industrial applications. Conventional technologies, viz. precipitation, filtration, liquid-liquid extraction, solid-liquid extraction, ion exchange, super critical extraction, electrowinning, electrorefining, electroslag ref＇ming, etc., which have been developed for the recovery of REMs, are not economically attractive. Biosorption represents a biotechnological innovation as well as a cost effective excellent tool for the recovery of rare earth metals from aqueous solutions. A variety ofbiomaterials such as algae, fungi, bacteria, resin, activated carbon, etc., have been reported to serve as potential adsorbents for the recovery of REMs. The metal binding mechanisms, as well as the parameters in- fluencing the uptake of rare earth metals and isotherm modeling are presented here. This article provides an overview of past achievements and current scenario of the biosorption studies carried out using some promising biosorbents which could serve as an economical means for recovering REMs. The experimental findings reported by different workers will provide insights into this re- search frontier.

Rare earth metals sorption recovery from uranium in situ leaching process solutions

Sorption characteristics of ion exchange resins 001 × 7, 005 × 8, D72 regarding rare earth metals （REM） during extraction from barren solution of uranium sorption in dynamic conditions were investigated. It was identified that D72 resin capacity on analyzed REM was 2.46 mg.cm-3 after passing 220 BV （bed volume） of initial solution with 95 % recovery of element of REM with the lowest affinity. Researches on REM desorption in dynamic conditions from investigated ion exchange resins by solution of 1.7 mol.L-1 HNO3 and 8.0 mol.L-1 NHnNO3 with 0.2 mol.L-1 HNO3 passing were carded out. It was identified that using desorption solution based on ammonium nitrate allows to achieve acceptable recovery degree of REM from the resin. The possibility of organization of a circulating desorption solution system increases the perspectives of nitrate ammonium solution usage.

Hainan to Promote the Exploration and Development of National Strategic Minerals and Prohibit the Mining of Rare Earth Metals

The Land and Resources Department of Hainan Province said on November 10 that the Overall Mineral Resources Plan of Hainan Province(2016-2020)(hereinafter referred to as the'Plan')has gone into effect with the approval of the Ministry of Land and Resources,and that the province will strongly promote the exploration and development of

Electron Donating Property and Catalytic Activity ofPerovskite-type Mixed Oxides (ABO_3) Consisting of Rare Earth and 3d Transition Metals

The catalytic activity of Perovskite-type mixed oxides (LaCoO3, PrCoO3 and SmCoO3) for the reduction of cyclohexanone to cyclohexanol with 2-propanol (Meerwein-PonndorfVerley reduction) has been studied. The data have been correlated with the surface electron donor properties of these mixed oxides

A Brief Introduction to the Rare Earths Research Institute,General Research Institute for Non-Ferrous Metals

The Rare Earths Research Institute(the former Rare Earths Research Laboratory)under the GRINM,the first institute to conduct R&D for rare earths(RE)industry in China,was founded in 1958.The Institutewas mainly engaged in the research work of comprehensive utilization of the mine at Baiyun-ebo,the largest

A Brief Introduction to the Rare Earths Research Institute,General Research Institute for Non-Ferrous Metals

The Rare Earths Research Institute(the former Rare Earths Research Laboratory)under the GRINM,the first institute to conduct R&D for rare earths(RE)industry in China,was founded in 1958.The Institutewas mainly engaged in the research work of comprehensive utilization of the mine at Baiyun-ebo,the largestRE mine in the world,and the ion adsorption type RE mineral in southern China.The ore decomposition,

Comparison of extraction abilities of deep eutectic solvents and aqueous acid solutions for extraction of rare earths and transition metals

In recent years,deep eutectic solvents have attracted increasing interest as effective extractants for the separation of both organic substances and metals from various objects.Acid-based deep eutectic solvents are most often used as extractants for the extraction of metals.In this work,for the first time,the extraction efficiency of transition metals and rare earth elements(Y,Zr,Nb,La,Ce,Pr,Nd,Sm,Eu,Gd,Tb,Dy,Ho,Er,Tm,Yb,Lu,Hf and Ta)from mining tailings and Na,K,Ca,Mg,Cu,Fe,Mn,Pb,Ba,Ni and Sr from biodiesel samples using acidic deep eutectic solvents and saturated aqueous solutions of the same acids(malonic,malic,tartaric and citric)is compared.For this,deep eutectic solvents based on acids and their aqueous saturated solutions were prepared and studied.The prepared mixtures were analyzed by IR spectroscopy to confirm the formation of eutectic solvents.Properties such as the density and viscosity of the resulting mixtures were also investigated,as this can be of key importance for the efficiency of metal extraction.The extraction of rare earth metals from mining tailings took a long time(up to several days),while the extraction of metals from fuel took no more than 30 min.Atomic emission spectral methods were used as an analysis method.It is shown that the extraction efficiency with aqueous solutions is better than that with eutectic solvents,which casts doubt on the need for deep eutectic solvents use in this area.

The World Production and Trade of Rare Earth Elements： The Position of the Pacific Area

In this paper we analyze the characteristics of the so-called rare earth elements （REEs） and its industrial applications. We present the policy, or lack thereof, in the countries in the Pacific Rim for its mining and commerce, and the current and future weight that rare earth minerals will have in international trade. The technological revolution experienced over the last 25 years, has brought the REEs to the public＇s attention for being instrumental in obtaining catalysts, lasers and optical fiber, luminescent substances and LEDs, superconductors, permanent magnets, batteries and ultra-capacitors. China＇s leading position as the supplier of these minerals worldwide, and its recent export restriction policy for domestic industrial activities have driven up international prices. Price increase for REEs is leading to the need for both recycling and its replacement. It has also led other countries in the Asia Pacific Rim to prospect new potential sites on their own territories, or even to restart operations in deposits that had been previously abandoned. Those strategies will likely gain greater importance as environmental pollution problems associated with the exploitation, processing, and recovery of REEs increase.

Characteristics of highly differentiated granite and metallization of tungsten-tin, rare and rare earth metal in the eastern Nanling region, China

1 Introduction Massive tungsten-tin,rare and rare earth metals ore deposits were formed with the widespread granite magmatic activity in early Yanshanian period in the eastern Nanling region.Recent studies indicate that the Yanshanian highly differentiated-granite formation is closely related to the deposits of tungsten and tin,rare and rare earth metals mineralization in the region(Xiao

Hydrogen production from coke oven gas over LiNi/γ-Al_2O_3 catalyst modified by rare earth metal oxide in a membrane reactor

The performance of LiNi/γ-Al2O3 catalysts modified by rare earth metal oxide （La2O3 or CeO2） packed on BCFNO membrane reactor was discussed for the partial oxidation of methane （POM） in coke oven gas （COG） at 875 ℃. The NiO/γ-Al2O3 catalysts with different amounts of La2O3 and CeO2 were prepared with the same preparation method and under the same condition in order to compare the reaction performance （oxygen permeation, CH4 conversion, H2 and CO selectivity） on the membrane reactor. The results show that the oxygen permeation flux increased significantly with LiNiREOx/γ-Al2O3 （RE = La or Ce） catalysts by adding the element of rare earth especially the Ce during the POM in COG. Such as, the Li15wt%CeO29wt%NiO/γ-Al2O3 catalyst with an oxygen permeation flux of 24.71 ml·cm^-2·min^-1 and a high CH4 conversion was obtained in 875 ℃. The resulted high oxygen permeation flux may be due to the added Ce that inhibited the strong interaction between Ni and Al2O3 to form the NiAl2O4 phase. In addition, the introduction of Ce leads up to an important property of storing and releasing oxygen.

Research progress in rare earths and their composites based electrode materials for supercapacitors

Supercapacitor is an imminent potential energy storage system,and acts as a booster to the batteries and fuel cells to provide necessary power density.In the last decade,carbon and carbonaceous materials,conducting polymers and transition metal oxide/hydroxide based electrode materials have been made to show a remarkable electrochemical performance.Rare-earth materials have attracted significant research attention as an electrode material for supercapacitor applications based on their physicochemical properties.In this review,rare earth metals,rare earth metal oxides/hydroxides,rare-earth metal chalcogenides,rare-earth metal/carbon composites and rare-earth metal/metal oxide composites based electrode materials are discussed for supercapacitors.We also discuss the energy chemistry of rare-earth metal-based materials.Besides the factors that affect the performance of the electrode materials,their evaluation methods and supercapacitor performances are discussed in details.Finally,the future outlook in rare-earth-based electrode materials is revealed towards its current developments for supercapacitor applications.

Some Rare Earth Metallic Organohydrides with Biindenyl as the Ligand

Introduction It is well known that organometallic hydrides of rare earth metals are the catalysts and reducing reagents for the catalysis polymerization of alkenes and the catalysis hydrogenation of alkenoalkynes. There are four methods for the syntheses of organometallic hydrides of rare earth metals:（1） the thermal atomization of metals, i.e., the interaction of a rare earth metal with alkenes with a terminal alkyne;（2） the Ln—Cσ bond is broken with H;;（3） metal-

Research and Development of Rare Earth Advanced Materials in China

China is rich in resources of rare earths(REs). Based on tremendous work, China has made great achievements in research and development of REs since 1980s, and the production of RE has won the leading position in the world. The application of RE elements in advanced materials have progressed significantly during the past years. The wide range of rare earth application in China has been reviewed and discussed in this paper, including the development of advanced RE materials (RE-Al alloys, rare earth nonferrous metal alloys, rare earth luminescent materials, rare earth hydrogen storage materials, rare earth permanent magnet and rare earth compounds used in agriculture, i.e., rare earth micronutrient fertilizer etc.) End the research of new RE materials (high T-c rare earth superconductor, rare earth electronic and photonic materials, rare earth ceramics and rare earth precious metal alloys). Finally, the further development works to be required are as follow: (1) to enhance the applied fundamental research, study the intrinsic properties of rare earth elements and develop less well known uses; (2) to undertake the applied research of median and heavy rare earth and find a way out of the unbalance of RE resources in the various applications; (3) to strengthen the applied research of RE element's in energy field, solving the energy-related, energy-saved and environmental problems.

New cadmium and rare earth metal tungstates with the scheelite type structure

New cadmium and rare earth metal tungstates with the formula Cd0.25RE0.50 0.25WO4 （RE=Nd, Sin, Eu, Gd, D-statistical distrib- uted vacancies in cation sublattice） were synthesized by the solid-state reaction between CdWO4 and corresponding RE2W209. The obtained phases crystallize in the scheelite type structure. The Cd0.25RE0.5 0.25WO4 compounds were characterized by X-ray diffractometer （XRD）, （DTA-TG）, infrared （IR） and EPR methods.

Magnetic Behavior of Some Rare-Earth Transition-Metal Perovskite Oxide Systems

Magnetic properties were investigated for the rare-earth 3d-transition metal oxides with the perovskite structure. Intriguing magnetic phenomena were reviewed for a few systems:magnetization peak effect in the titanates, magnetization reversal in the chromites and metallic ferromagnetism in the cobaltites. The results suggest an important role of the rare-earth ions for the magnetic properties of such complex oxides.

Influence of oxidant KMnO_4 on film-forming process of rare earth metal conversion coating on LY12 aluminum alloy

A Cu/Al galvanic couple was established to study the influence of the oxidantKMnO_4 on the film-forming process of rare earth metal (REM) conversion coating on LY12 aluminumalloy. It is found that the galvanic couple simulative experiment accords with the actual immersion,and it can be substantially used to simulate the behavior of LY12 aluminum alloy in thefilm-forming process. It is showed that the formation of the coating is quickened in CeCl_3 solutioncontaining KMnO_4 compared with that not containing KMnO_4. XPS results reveal that the coatingformed on cathode is composed of oxide or hydroxide of Ce and Mn, so the mechanism of formation ofREM conversion coating changes when KMnO4 is added.

Rare Earth Application in Sealing Anodized Al-Based Metal Matrix Composites

A new method for corrosion protection of Al-based metal matrix composites (MMC) was developed using two-step process, which involves anodizing in H2SO4 solution and sealing in rare earth solution. Corrosion resistance of the treated surface was evaluated with polarization curves. The results showed that the effect of the protection using rare earth sealing is equivalent to that using chromate sealing for Al6061/SiCp. The rare earth metal salt can be an alternative to the toxic chromate for sealing anodized Al MMC.

Preparation and Characterization of Rare Earth Metal and Alloy Target Materials for Manufacturing Magneto-Optical Disks

The studies were made on the preparation processes of the rare earth metal and alloy target materials and their characterization. In this work the rare earth metals were prepared by electrolysis of the oxide in molten salt for Nd metal and metallothermic reduction of the fluorides for Gd, Tb, Dy metals. After vacuum refining and distillation purification these rare earth metals were used for manufacturing the element targets, mosaic targets and as the starting materials of preparing the rare earth-transition metal (RE-TM) alloy targets. The four kinds of Dy-FeCo, NdDy-FeCo, Tb-FeCo and GdTb-FeCo alloy targets with diameter of 100 mm and thickness of 3 mm were prepared using powder metallurgical technique. The oxygen content and microstructure of the prepared RE-TM cast alloys and sintered targets were analyzed. The features and requirements of the RE-TM alloy sputtering target materials were also discussed.