Showing papers on "Carbide published in 1985"

Cutting element for drill bits

Abstract: A cutting element which has a metal carbide stud having a conic tip formed with a reduced diameter hemispherical outer tip end portion of said metal carbide stud. A layer of polycrystalline material, resistant to corrosive and abrasive materials, is disposed over the outer end portion of the metal carbide stud to form a cap. An alternate conic form has a flat tip face. A chisel insert has a transecting edge and opposing flat faces. It is also covered with a PDC layer.

Growth of beta-silicon carbide whiskers by the VLS process

Abstract: Beta-silicon carbide whiskers are being grown by a vapour-liquid-solid (VLS) process which produces a very high purity, high strength single crystal fibre about 6μm in diameter and 5–100 mm long. Details of the growth process are given along with a general explanantion of the effects of the major growth parameters on whisker growth morphology.

Magnetic recording medium

Abstract: PURPOSE:To obtain a magnetic recording medium excellent in gloss and magnetic characteristics by providing a magnetic recording layer contg. a binder and a magnetic powder contg. iron carbide on a base material to constitute the magnetic recording medium. CONSTITUTION:The magnetic recording layer contg. the binder and the magnetic powder contg. iron carbide is provided on the base material. The binder consists of at least one of (a) copolymer of vinyl chloride, vinyl acetate and monomer having a polar group, (b) copolymer of vinyl chloride and monomer having a polar group, (c) polyvinyl acetal resin, (d) nitrocellulose and (e) polyurethane resin. The powder contg. iron carbide is obtained, for example, by allowing particles of iron oxyhydroxide or iron oxide to contact with a mixture of reductive gas containing no carbon. Thereby, excellent gloss and magnetic characteristics are obtained.

Effect of Reinforcement on the Pitting Behavior of Aluminum‐Base Metal Matrix Composites

Abstract: This paper examines the effect of graphite and silicon carbide reinforcements on the pitting behavior of graphite/aluminum (Gr/Al) and silicon carbide/aluminum (SiC/Al) metal matrix composites. Electrochemical corrosion tests were performed on both Gr/Al and SiC/Al composite specimens. Identical tests were completed on powder metallurgy processed aluminum and wrought aluminum of the same composition. The electrochemical behavio of the SiC/Al composites was essentially identical to that of the powder processed and wrought aluminum alloys; however, the pitting attack on the SiC/Al composites was distributed more uniformly across the surface, and the pits penetrated to significantly less depths. The presence of graphite in the Gr/Al composites did not cause an electropositive shift in corrosion potential as anticipated, but caused a substantial decrease in resistance to passive film breakdown. This effect is the predominant reason for the poor performance of Gr/Al composites in marine environments.

Method and composition for producing hard surface carbide insert tools

Abstract: A hard surfaced heavy duty cutting tool having an abrasive insert and method for hard surfacing and bonding metallic materials. The composition used in hard surfacing comprises a slurry coating including a high nickel, metal alloy powder and a fluxing agent. The slurry composition is fused at temperatures of about 1830°-1925° F. to bond an abrasive cutting element, such as tungsten carbide in a base metal matrix, to a cutting tool to form the primary working element thereof. The slurry composition is also fused at the same temperature range to form a wear surface of the tool adjacent to the abrasive insert as a hard surface, wear resistant coating in which abrasive compounds and other materials may be incorporated.

Bonding mechanism between silicon carbide and thin foils of reactive metals

Abstract: Pressureless-sintered SiC pieces and SiC single crystals were joined with foils of reactive metals at 1500° C (1773 K) for titanium and zirconium foils or at 1000° C (1273 K) for Al/Ti/Al foils. Bend testing at various temperatures up to 1400° C (1673 K), optical and electron microscopy, and electron-probe X-ray microanalysis studies were carried out on the specimens. From the results, it was concluded that the fairly high bond strength of titanium-foil joined SiC specimens might be attributed to the formation of a Ti3SiC2 compound, since good lattice matching between SiC and Ti3SiC2 was obtained in the SiC single crystals. Also in the Al/Ti/Al-foil joined SiC, high bond strength was obtained, but it decreased steeply at 600° C (873 K) because of a retained aluminium phase. The bond strength in the zirconium-foil joined SiC was low.

Thermal conductivity behavior of boron carbides

Abstract: Knowledge of the thermal conductivity of boron carbide is necessary to evaluate its potential for high temperature thermoelectric energy conversion applications. We have measured the thermal diffusivity of hot-pressed boron carbide B1-xCx samples as a function of composition (0.1 ≤ x ≤ 0.2), temperature (300 K to 1700 K) and temperature cycling. These data in concert with density and specific heat data yield the thermal conductivities of these materials. We discuss these results in terms of a structural model that has been previously advanced by two of us (D.E. and C.W.) to explain the electrical transport data. Some novel mechanisms for thermal conduction are briefly discussed.

Semiconductor memory device

Abstract: PURPOSE:To obtain an amorphous nonvolatile memory, which has excellent holding characteristics and reproducibility and a large area and large capacitance and cost thereof is low, by using an amorphous silicon carbide film in place of an amorphous silicon nitride film. CONSTITUTION:An insulating substrate 11, a lower electrode 12, an N type 13, which is hydrogenated previously by amorphous silicon and to which phosphorus is doped to a high degree, and an N type 14 to which phosphorus is doped similarly to a low degree are formed in the order. An silicon oxide film 15 in which amorphous silicon in oxidized through plasma anodizing, etc., a film 16, which consists of a hydrogenated amorphous silicon carbide film and contains carbon by 35atom% or more, and an upper electrode 17 are shaped in the order. Accordingly, a device having performance, which has not exist as nonvolatile memories, such as, a holding time of ten years or more, a writing time of 0.1musec or less, even fast erasing speed, a large area and large capacitance and low cost is obtained.

Boron-carbide-aluminum and boron-carbide-reactive- metal cermets

Abstract: Hard, tough, lightweight boron-carbide-reactive metal composites, particularly boron-carbide-aluminum composites, are produced. These composites have compositions with a plurality of phases. A method is provided, including the steps of wetting and reacting the starting materials, by which the microstructures in the resulting composites can be controllably selected. Starting compositions, reaction temperatures, reaction times, and reaction atmospheres are parameters for controlling the process and resulting compositions. The ceramic phases are homogeneously distributed in the metal phases and adhesive forces at ceramic-metal interfaces are maximized. An initial consolidation step is used to achieve fully dense composites. Microstructures of boron-carbide-aluminum cermets have been produced with modulus of rupture exceeding 110 ksi and fracture toughness exceeding 12 ksi√in. These composites and methods can be used to form a variety of structural elements.

Rock bits having metallurgically bonded cutter inserts

Abstract: A cladding process is disclosed wherein hard carbide cutter inserts, as well as polycrystalline diamond composites, are metallurgically bonded into an exterior core of a rock bit cone or a drag bit body. The cladding is bonded onto the exterior surface of the core of the cone or the drag bit by a powder metallurgy process. A thin layer or coating of a suitable metal, preferably nickel, is provided on, for example, the carbide inserts, prior to mounting into the core. The coating prevents degradation of the carbide through loss of carbon into the core during the powder metallurgy process and accommodates mismatch of thermal expansion between the cutter insert and the core.

The effect of binder thickness and residual stresses on the fracture toughness of cemented carbides

Abstract: Much of the data on WC-Co cermets show that the fracture toughness,KIc, increases with increasing tungsten carbide grain size at fixed volume fraction of the cobalt binder phase. It is shown that the origin of this effect can be explained on the basis of the plane stress fracture of constrained cobalt phase and the periodic internal stresses arising due to differential thermal contraction of the two phases. Quantitative models have been derived which take these two effects into account. The effect of macroscopic residual stresses, such as those generated by milling WC-Co drilling inserts, on the apparent toughness has also been analysed. It is shown that for the chevron-notched type specimen the macroscopic residual stress affects not only the maximum load but also the length of the crack at which the maximum occurs. A graphical method is presented which permits the evaluation of the true K‡Ic.

The microstructural response of mill-annealed and solution-annealed INCONEL 600 to heat treatment

Abstract: Samples of INCONEL* 600 were examined in the mill-annealed and solution-annealed states, and after isothermal annealing at 400 °C and 650 °C. The corrosion behavior of the samples was examined, analytical electron microscopy was used to determine the microstructures present and the chemistry of grain boundaries, and Auger electron spectroscopy was used to measure grain boundary segregation. Samples of different alloys in the mill-annealed state were found to have quite different microstructures, with Cr-rich M7C3 carbides occurring either along grain boundaries or in intragranular sheets. The corrosion behavior of the samples correlated well with the occurrence of grain boundary chromium depletion. Solution annealing at 1190 °C caused dissolution of all carbides, whereas at 1100 °C the carbides either dissolved or the grain boundaries moved away from the carbides, depending upon alloy carbon content. Low-temperature annealing at 400 °C had little effect on millannealed or fully solutionized samples, but in samples with intragranular carbides present, the grain boundaries moved until intersecting or adjacent to the carbides. Isothermal annealing at 650 °C caused carbide nucleation and growth at grain boundaries in fully solutionized samples. Chromium depletion at grain boundaries accompanied carbide precipitation, with a minimum chromium level of 6 wt pct achieved after 5 hours. Healing was found to occur after 100 hours. Solution-annealed samples with intragranular carbides present had more rapid corrosion kinetics since the grain boundaries moved back to the existing carbides. Thermodynamic analysis of the chromium-depletion process showed good agreement with experimental measurements. The Auger results found only boron present at grain boundaries in the mill-annealed state. Aged samples had boron, nitrogen, and phosphorus present, with phosphorus and nitrogen segregating to the greatest extent. The kinetics of phosphorus segregation are much slower at 400 °C compared with 650 °C.

Laser Surface Alloying of Titanium Substrates with Carbon and Nitrogen

Abstract: Observations are reported on the laser surface alloying of commercial purity (CP) Ti and Ti–6Al–4V alloy with carbon and of CP Ti and Ti–15 Mo alloy with nitrogen. Repeated laser melting of substrates precoated with Dag graphite was used for carbon alloying, while alloying with nitrogen was done by laser melting in a nitrogen flow. Structural studies included X-ray diffraction and electron microscopy. Both alloying procedures produce hardened surface layers up to ∼650 HV using carbon and >∼ 1000 HV using nitrogen. This hardening resulted from the formation of TiC and TiN respectively, including primary dendritic carbide and nitride.

Phase constitution and lattice parameter relationships in rapidly solidified (Fe0.65Mn0.35)0.83 Al0.17-xC and Fe3Al-xC pseudo-binary alloys

Abstract: A quasi-equilibrium temperaturevs carbon-concentration phase diagram of rapidly solidified pseudo-binary (Fe0.65Mn0.35)0.83Al0.17-xC alloys was determined after heat treatment in the 823 to 1323 K range. Lattice parameter relationships of rapidly solidified (Fe0.65Mn0.35)0.83Al0.17-xC and Fe3Al-xC alloys in the ferrite, austenite, and perovskite carbide phases were established as a function of the carbon concentration. This study shows that when a high concentration of carbon is present in the alloys a perovskiteL′l2 carbide is formed directly from the rapid solidification process. It is established also in this study that the carbon atom contribution to the lattice parameter increase in the fcc-based cubic crystal is greater in the disorderedγ-phase than in the ordered (L′l2 structure)κ-phase.

Composite by infiltration

Abstract: A composite is produced by forming a porous compact of a ceramic member selected from the group consisting of boron carbide, hafnium carbide, hafnium nitride, niobium carbide, niobium nitride, silicon carbide, silicon nitride, tantalum carbide, tantalum nitride, titanium carbide, titanium nitride, vanadium carbide, vanadium nitride, zirconium carbide and zirconium nitride, and infiltrating the compact with a member selected from the group consisting of barium fluoride, calcium fluoride, magnesium fluoride, strontium fluoride, cerium fluoride, dysprosium fluoride, gadolinium fluoride, lanthanum fluoride, samarium fluoride, yttrium fluoride, and a mixture of said fluoride with a metal oxide.

Low temperature carbide precipitation in a nickel base superalloy

Abstract: A M23C6 carbide phase has been observed to precipitate at relatively low temperatures (732 to 760 °C) in a nickel base superalloy.* Transmission Electron Microscopy shows the low temperature carbide to reside at the grain boundaries in a continuous morphology. The continuous carbide has a typical width of 25 to 40 nm with aspect ratios on the order of 30:1. The structure of the carbide is face-centered cubic with a lattice parameter (α0) of approximately 1.063 nm, which is typical of the M23C6 carbides that form at higher temperatures. STEM analysis indicates the carbide to have a typical M23C6 chemistry, enriched in chromium with lesser amounts of molybdenum, cobalt, and nickel. The formation of the continuous carbide occurs readily around 760 °C; however, at temperatures 55 °C lower the precipitation kinetics are significantly reduced. The extent of the low temperature carbide reaction is observed to be dependent upon the duration of the low temperature exposure and the degree of prior M23C6 stabilization at an intermediate temperature. Alloy modifications, involving hafnium additions and lower carbon levels, were studied with the aim of reducing the extent of this carbide reaction. Despite these chemistry modifications, the low temperature carbide was still observed to form to an appreciable extent. The presence of the continuous carbide is also observed to reduce the stress-rupture life of the alloy.

Process for the direct production of steel

Abstract: A process for the direct production of steel from particulate iron oxides or concentrates including two major steps in which in Step (1) the iron oxides are converted to iron carbide and in Step (2) steel is produced directly from the carbide in the basic oxygen furnace or the electric furnace. In the production of the carbide the oxides are reduced and carburized in a single operation using a mixture of hydrogen as a reducing agent and carbon bearing substances such as propane primarily as carburizing agents. Iron carbide thus produced is introduced as all or part of the charge into a basic oxygen furnace to produce steel directly without the blast furnace step. In order to make the steel making process auto-thermal, heat is supplied either by using the hot iron carbide from Step (1) or preheating the iron carbide or by including sufficient fuel in the iron carbide to supply the required heat by combustion.

Novel wear-resistant laser-engraved ceramic or metallic carbide surfaces for friction rolls for working elongate members, method for producing same and method for working elongate members using the novel friction roll

Abstract: The invention is to friction rolls for working elongate members, eg, webs or strands, such as crimper rolls, draw rolls, yarn package drive rolls comprising a roll having a generally cylindrical external surface and a ceramic, eg, alumina, mixtures of alumina and titania, chromia, zirconia, or metallic carbide, eg, tungsten carbide, coating bonded to the external surface, the coating being laser-engraved, that is, having a plurality of laser-formed depressions having a pattern covering substantially the entire exterior working surface of the roll and providing a uniform, wear-resistant surface texture over substantially the entire working surface

Abnormal grain growth and microcracking in boron carbide

Abstract: Boron carbide compacts sintered between 2220° and 2250° C showed abnormal grain growth that was associated with twinning and microcracking. The twin direction was 〈011〉. The microcracking was linked to thermal expansion anisotropy determined by high-temperature lattice constant measurement.

Multilayer coated cemented carbides

Abstract: Multilayer coated cemented carbides excellent in wear resistance and toughness are provided comprising a substrate of cemented carbide, an inner layer contacted with the surface of the substrate, and an outer layer contacted with the inner layer, the inner layer being a single layer and/or laminated layers consisting of at least one member selected from the group consisting of carbides, nitrides, carbonitrides, carboxynitrides, oxynitrides, boronitrides and borocarbonitrides of Ti, and the outer layer being a multilayer with a total thickness of 5 to 20 μm, consisting of a plurality of Al2 O3 layer each having a thickness of 001 to 2 μm, each consisting of an Al2 O3 film in which titanium oxide is dissolved or at most 30 vol % of titanium oxide is coexistent and being respectively divided by interlayers each having a thickness of 001 to 2 μm and each consisting of at least one member of the group consisting of TiC, TiN, TiCN, TiCNO, TiNO, Ti oxides Ti(B, N), Ti(B, N, C), SiC, AlN and AlON

Method for carbon control of carbide preforms

Abstract: The present invention provides a method for controlling the carbon content of dewaxed carbide preforms in a carbon containing furnace. The method includes the steps of placing the preforms in a carbon containing furnace and then heating the furnace to a predetermined temperature range between 800 and 1100 degrees Centigrade. At that temperature, a mixture of methane and hydrogen is introduced into the furnace chamber such that the amount of methane is between 10 and 90 percent of the amount of methane present at equilibrium for the reaction C solid +2H 2 CH 4 . The furnace chamber is maintained at its temperature for a first time period sufficient for the chemical reaction XC+2H2X+CH 4 (where X is selected from the group of W, Ti, Ta, Hf and No) substantially reaches equilibrium but shorter than the a second time period in which the reaction C solid +2H2CH 4 reaches equilibrium or the resident time of the gaseous mixture is less than the second time period.

Coated cemented carbide cutting tool

Abstract: The present invention is directed to a triple coated cemented hard metal carbide product in which a cemented metal carbide substrate is coated with, first, a metal carbide coating to promote coating adherence to the substrate, secondly, a metal nitride or carbonitride coating to promote crater wear resistance and, thirdly, a metal carbide outer layer to promote flank flank wear resistance in order to protect the cemented metal carbide substrate from corrosive atmosphere and abrasion due to frictional flank wear.

Composite rotary anode for X-ray tube and process for preparing the composite

Abstract: A method for the diffusion bonding of a graphite member to a metallic surface as part of a composite rotary anode for an X-ray tube is set forth. In the completed structure a compound laminate separating and metallurgically bonded to the graphite member and to the metallic surface consists of, in sequence, a layer comprising carbide of vanadium and of a metal selected from the group consisting of molybdenum and tungsten, a layer of metal selected from the group consisting of vanadium and vanadium alloys, a zone of interdiffused metals comprising platinum and vanadium and then a continuous layer comprising platinum or platinum alloy.