Carbide Research Articles

Preparation, Crystal Structure, and Magnetic Properties of Rare Earth Ruthenium and Osmium Carbides with La3.67FeC6 Type Structure

The new carbides Gd3.67RuC6 and Ln3.67OsC6 (Ln = La–Nd, Sm) were prepared by arc-melting of cold-pressed pellets of the elemental components. Their hexagonal (P63/m) La3.67FeC6 type crystal structure was refined from X-ray powder diffraction data of La3.67OsC6 (a = 889.1(1) pm, c = 535.1(1) pm) and Pr3.67OsC6 (a = 874.9(2) pm, c = 523.7(1) pm). The occupancy parameters of one La and one Pr site were refined to 0.35(5) and 0.34(5), respectively, in agreement with the highest possible occupancy for steric reasons of 1/3. The C–C distances in the C2 pairs are 139(6) pm and 137(3) pm, respectively, indicating double bonds. The environment of the osmium atoms is compatible with the 18-electron rule. The magnetic properties of several carbides were determind with a SQUID magnetometer. The lanthanum compounds La3.67RuC6 and La3.67OsC6 are Pauli paramagnetic. The magnetic properties of the other compounds are dominated by the magnetic moments of the rare earth atoms. Most order ferrimagnetically with Curie temperatures varying between 5(± 3) and 32(± 6) K for Ce3.67OsC6 and Pr3.67RuC6, respectively. The cerium atoms in Ce3.67RuC6 and Ce3.67OsC6 are essentially trivalent, and the samarium compounds show Van Vleck behavior. Praparation, Kristallstruktur und magnetische Eigenschaften von Seltenerd-Ruthenium- und Osmium-Carbiden mit La3.67FeC6-Struktur Die neuen Carbide Gd3.67RuC6 und Ln3.67OsC6 (Ln = La–Nd, Sm) wurden durch Aufschmelzen von kaltgepressten Pillen der Elemente im Lichtbogenofen dargestellt. Ihre hexagonale (P63/m) La3.67FeC6-Struktur wurde aus Rontgen-Pulverdiffraktometerdaten von La3.67OsC6 (a = 889.1(1) pm, c = 535.1(1) pm) und Pr3.67OsC6 (a = 874.9(2) pm, c = 523.7(1) pm) verfeinert. Fur die Besetzungsparameter von je einer La- und einer Pr-Lage wurden die Werte 0.35(5) und 0.34(5) erhalten, im Einklang mit der aus sterischen Grunden maximal moglichen Besetzung von 1/3. Die C–C-Abstande in den C2-Paaren betragen 139(6) pm bzw. 137(3) pm entsprechend einer Doppelbindung. Die Konfiguration der Osmiumatome scheint der 18-Elektronenregel zu entsprechen. Die magnetischen Eigenschaften mehrerer Carbide wurden mit Hilfe eines SQUID-Magnetometers untersucht. Die Lanthanverbindungen La3.67RuC6 und La3.67OsC6 sind Pauli-paramagnetisch. Die magnetischen Eigenschaften der ubrigen Carbide werden durch den Magnetismus der Seltenerdatome bestimmt. Die meisten zeigen Ferrimagnetismus mit Curie-Temperaturen zwischen 5(± 3) und 32(± 6) K fur Ce3.67RuC6 bzw. Pr3.67RuC6. Die Ceratome in Ce3.67RuC6 und Ce3.67OsC6 sind im wesentlichen dreiwertig und die Samariumverbindungen zeigen Van Vleck-Verhalten.

High speed steels reinforced with carbides by mechanical alloy

En este trabajo se estudia la eficacia del empleo de la aleacion mecanica, en el proceso de fabricacion de materiales compuestos de matriz metalica (base acero rapido M2) mediante tecnicas pulvimetalurgicas. Del analisis de los materiales obtenidos, acero rapido M2 reforzado con WC, se deduce que la aleacion mecanica resulta ser un metodo eficaz para la fabricacion de estos compuestos, ya que se alcanzan unas excelentes propiedades mecanicas, que superan ampliamente a las que presentan los mismos aceros reforzados con carburos mediante procesos pulvimetalurgicos convencionales

Degradation Damage Evaluation of High Temperature Structural Components by Electrochemical Anodic Polarization Test

The structural steels of power plant show the decrease of mechanical properties due to degradation such as temper embrittlement, creep damage and softening during long-term operation at high temper ature. The typical causes of material degradation damage are the creation and coarsening of carbides(M23C6, M6C) and the segregation of impurities(P, Sb and Sn) to grain boundary. It is also well known that material degradation induces the cleavage fracture and increases the ductile-brittle transition temperature of steels. So, it is very important to evaluate degradation damage to secure the reliable and efficient service condition and to prevent brittle failure in service. However, it would not be appropriate to sample a large test piece from in-service components. Therefore, it is necessary to develop a couple of new approaches to the non-destructive estimation technique which may be applicable to assessing the material degradation of the components with not to influence their essential strength. The purpose of this study is to propose and establish a new electrochemical technique for non-destructive evaluation of material degradation damage for Cr-Mo steels which is widely used in the high temperature structural components. And the electrochemical anodic polarization test results are compared with those of semi-nondestructive SP test.

C-0.5Mo鋼の水素侵食抵抗性におよぼす塊状M<SUB>23</SUB>C<SUB>6</SUB>炭化物の役割

C-0.5Mo鋼の水素侵食抵抗性におよぼす塊状M<SUB>23</SUB>C<SUB>6</SUB>炭化物の役割

Recycling of cemented carbides: K.Stjernberg, J.Johnson. (Teledyne Metalworking Products, USA.)

Recycling of cemented carbides: K.Stjernberg, J.Johnson. (Teledyne Metalworking Products, USA.)

Sintering microstructure and properties of submicron cemented carbides: M.Leiderman et al. (Technion, Haifa, Israel.) Powder Metall., vol 40, no 3, 1997, 219–225

Sintering microstructure and properties of submicron cemented carbides: M.Leiderman et al. (Technion, Haifa, Israel.) Powder Metall., vol 40, no 3, 1997, 219–225

Submicron carbides making the grade

Submicron carbides making the grade

Effect of sintering atmosphere and structure on properties of cemented carbides

Effect of sintering atmosphere and structure on properties of cemented carbides

Influence Of Local Damage On The CreepBehaviour Of High Speed Steels

High speed steels are investigated as to their short term creep behaviour. In uniaxial creep tests under constant stress a distinct influence of the distribution of primary and eutectic carbides on the creep curve was found. Micrographs show the developement of local damage due to carbide cleavage even in the early stage of the test. The creep deformation was numerically modelled by use of FEM on a microscopical scale. The role of particle arrangement and local damage was investigated by numerical studies.

Properties of fine grained sintered carbides made by reduction and carburization

Properties of fine grained sintered carbides made by reduction and carburization

New types of cemented carbide coatings ‘diadur’

New types of cemented carbide coatings ‘diadur’

A study on the evaluation for material degradation of 0.0Cr-0.5Mo steel by a electrochemical polarization method

The contents of this paper include a non-destructive technique for evaluating the degradation of the boiler superheater tube in a fossil power plant through an electrochemical polarization test. Correlation between Ip of polarization parameter and SP-DBTT for the superheater tubes in long-term use was obtained. 1.0Cr-0.5Mo steel was degraded by softening, and the degree of degradation was dependent upon carbides with Cr and Mo elements. Since brittle fracture at low temperature and ductile fracture mode at high temperature were shown, similarity between standard Charpy and small punch tests could be found. In addition, SP-DBTT showing the degree of degradation was higher, as the time-in use of the materials got longer. Electrolyte including picric acid of 1.3 g in distilled water of 100ml at 25.deg. C temperature and sodium tridecylbenzene sulfonate with 1g could be applied to evaluate the degradation of 1.0Cr-0.5Mo steel by means of the electrochemical polarization test. Ip and Ipa values measured through the electrochemical test are the appropriate parameters for representing the degradation of the superheater tube(1.0Cr-0.5Mo steel) for the fossil power plant. It is poassible to evaluate the degradation of materials with different time histories electrochemically, by Ip value only, at field test.

Cryogenic fracture behaviors and polarization characteristics according to sensitizing heat treatment on structural material of the nuclear fusion reactor

The cryogenic fracture behaviors of austenitic stainless steel HN2 developed for nuclear fusion reactor were evaluated quantitatively by using the small punch(SP) test. The electrochemical polarization test was applied to study thermal aging degradation of HN2 steel. The X-ray diffraction(XRD) analysis was conducted to detect carbides and nitrides precipitated on the grain boundary of the heat treated HN2 steel. The mechanical properties of the HN2 steel significantly decreased with increasing time and temperature of heat treatment or with decreasing testing temperature. The integrated charge(Q) obtained from electrochemical polarization test showed a good correlation with the SP energy(ESP) obtained by means of SP tests. From the results observed in the x-ray diffraction and anodic polarization curve, it was known that the material the grain boundary. Combining SP test and electrochemical polarization test, it could be useful tools to non-destructively evaluate the cryogenic fracture behaviors and the aging degradation for cryogenic structural material.

Formation of Silicon Carbide from Rice Hulls

SiC whiskers and particles have been produced from rice hulls. The process involves three major steps: coking in free air, reaction at high temperature in a reducing atmosphere of hydrogen gas, and separation of formed SiC from excess carbon by wet methods. The processing steps are reviewed and the chemistry of the process is discussed. The produced SiC was added to a molten Zn–5%Al alloy to check its potency as a reinforcing material. © 1998 Published on behalf of Canadian Institute of Mining and Metallurgy by Elsevier Science Ltd. All rights reserved.ResumeDes barbes et des particules de SiC ont été produites à partir d'enveloppes de riz. Le processus implique trois é tapes majeures: cokefaction a l'air libre, réaction à haute température dans une atmosph è re reductrice de gaz hydrogene et separation du SiC forme de l'exces de carbone par des methodès humldes. On revoie les etapes de traitement et on discute de la chimie du processus. On a ajoute le SiC ainsi produit à un alliage fondu de Zn–5%Al afin de verifier son potentiel comme matériau de reforcement. © 1998 Published on behalf of Canadian Institute of Mining and Metallurgy by Elsevier ScienceLtd. All nghts reserved.

Effect of Micro-Cracks in Coating on Performance of CVD Coated Carbide Cutting Tool

Effect of Micro-Cracks in Coating on Performance of CVD Coated Carbide Cutting Tool

Zur Synthese und Kristallstruktur der ternären Carbide Na2PdC2 und Na2PtC2

Syntheses and Crystal Structures of Ternary Carbides Na2PdC2 and Na2PtC2Na2PdC2 and Na2PtC2 were synthesized by the reaction of sodium carbide with palladium and platinum respectively. The crystal structures could be solved from X‐ray powder diffraction data (space group: P3m1, Z = 1). Both compounds crystallize in a new structure type with [M(C2)2/22−] chains (MPd, Pt) as the characteristic structural unit. The existence of a CC triple bond was confirmed by Raman spectroscopy.

Design of cemented carbide ring drills: L. Gu et al. (Jiamusi Inst. of Techsnology, China.)

Design of cemented carbide ring drills: L. Gu et al. (Jiamusi Inst. of Techsnology, China.)

Perfluoroalkylsulfonates, sulfonimides, and sulfonyl methides, and electrolytes containing them

Perfluoroalkylsulfonates, sulfonimides, and sulfonyl methides, and electrolytes containing them

Machinability of ceramic and WC-Co green compacts

Machining pressed compacts of ceramic and WC-Co materials can be the most cost effective way of forming the bodies prior to sintering when the required number of pieces is small. In this study, in order to clarify the machinability for turning, the and the WC-Co green compacts unsintered were machined under different cutting conditions with various tools. Absorbing chips by vacuum hose decreases tool wear. The tool wear becomes larger in the order of the ceramic, CBN and cemented carbide tools in machining the green compacts. In machining the WC-Co green compacts, the tool wear becomes larger in the order of the ceramic, cemented carbide and CBN tools. The land of cutting edge does not affect tool wear. When machining with cemented carbide tool, the tool wear i equal cutting length is nearly identical in spite of the increase of cutting spee, and the roughness of machined surface was the best in the cutting speed of 90 m/min. The tool wear decreases with the increase of rake angle and relief angle and with the decrease of nose radius. The machined surfaces become worse with the increase of feed rate and depth of cut, and with the decrease of rake angle and relief angle. The tool wear is not affected by the feed and depth of cut.

Density functional study of silicon carbide cluster cations C4+, C3Si+, C2Si2+, CSi3+ and Si4+

Dans ce travail, nous avons calcule par les methodes de fonctionnelle de la densite, les geometries d'equilibre, les moments dipolaires et les frequences vibrationnelles des plus bas etats electroniques des cations silico carbones a quatre atomes, correspondant aux conformations geometriques les plus probables. Pour C 4 + , les geometries lineaire et cyclique sont quasi degenerees. SiC 3 + et Si 4 + possedent une structure cyclique dans leur etat fondamental, Si 2 C 2 + est lineaire, tandis que Si 3 C + possede une structure T symetrique avec un atome central de carbone. L'analyse comparative de la repartition de la charge atomique pour les clusters a trois et quatre atomes fournit un schema coherent qui permet de comprendre la structure geometrique des etats fondamentaux. Enfin, nous presentons quelques regles generales concernant la reactivite des atomes de silicium.