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Showing papers on "Carbide published in 1986"


Journal ArticleDOI
TL;DR: A review of the hard coating literature is given and includes in addition to nitrides and carbides also oxides, borides, mixed compounds, metals and alloys, and "diamondlike" carbon coatings.
Abstract: Hard‐coating materials range from ultrahard materials such as ‘‘diamondlike carbon’’ through refractory compounds to alloys. However, transition‐metal carbides and nitrides have achieved by far the highest level of commercial success. Titanium nitride and titanium carbide are the most studied and used. In this paper a review of the hard coating literature is given and includes in addition to nitrides and carbides also oxides, borides, mixed compounds, metals and alloys, and ‘‘diamondlike’’ carbon coatings. Only coatings grown from the vapor phase are discussed. Some considerations involved in selecting coating/substrate combinations as well as basic concepts of hardness and hardness measurements are also given. For example, it is shown that in order to measure the hardness of the coatings correctly the ratio between the film thickness and the depth of the indentation has to exceed a critical value, which depends on the coating/substrate combination. For TiN on steel, the coating thickness has to be a fact...

432 citations


Journal ArticleDOI
TL;DR: In this article, the oxidation kinetics of several single-crystal and polvcrystalline silicon carbide materials and singlecrystal silicon in dry oxygen over the temperature range 1200° to 1500°C were fitted to the linear-parabolic model of Deal and Grove.
Abstract: The oxidation kinetics of several single-crystal and polvcrystalline silicon carbide materials and single-crystal silicon in dry oxygen over the temperature range 1200° to 1500°C were fitted to the linear-parabolic model of Deal and Grove. The lower oxidation rates of silicon carbide compared to silicon can be rationalized by additional consumption of oxidant in oxidizing carbon to carbon dioxide. The (000J) Si face of the silicon carbide platelets exhibited lower parabolic oxidation rates than the (0001) C face, by a factor of 10 at 1200°C. Apparent activation energies increased from a value of ∼120 kJ/mol below 1400°C to a value of ∼300 kJ/mol above this temperature. The (0001) Si face exhibited this high activation energy over the entire temperature range. The controlled nucleation thermally deposited material exhibited the highest oxidation rates of the polycrystalline materials followed by the hot-pressed and sintered α-silicon carbides. In general, the oxidation rates of the polycrystalline materials were bracketed by the oxidation rates of the basal planes of the single-crystal materials. Higher impurity concentrations and higher density of nucleation sites led to a greater susceptibility to crystallization of the scale which significantly complicated the oxidation behaviors observed. When crystallization of the oxide scale occurred in the form of a layer of spherulitic cristobalite crystals, a retardation of the oxidation rates was observed. An accelerated oxidation behavior was found when this coherent layer was superseded by the formation of fine mullite crystals.

323 citations


BookDOI
01 Jan 1986
Abstract: Processing and Fabrication of Multiphase Ceramics.- Sintering of Multiphase Ceramics.- The Morphological Stability of Continuous Intergranular Phases.- Role of Shear in the Sintering of Composites.- HIP of Liquid Phase Sintered Ceramic Composites.- Sinterable Yttria-Doped Zirconia Powders Chemically Coprecipitated in Non-Aqueous Medium.- Microstructural and Chemical Aspects of a Strontia Sintering Aid on Mg-PSZ.- Phase Relationships in Y-Si-A1-O-N Ceramics.- The Fabrication of Composite O'-B' Sialon Ceramics.- Ceramic Eutectic Composites.- Nickel Oxide-Based Aligned Eutectics.- Imperfections in the Directionally Solidified Structure of NiO-CaO Eutectic.- CVD-Processing of Ceramic-Ceramic Composite Materials.- CVD Fabrication of In-situ Composites of Non-oxide Ceramics.- Preparation of Boron Nitride/Boron Carbide Ceramics by Pyrolysis of Boric Acid-Glycerin Condensation Product.- Porous and Dense Composites for Sol-Gel.- Non-Equilibrium Surface Conditions and Microstructural Changes Following Pulsed Laser Irradiation and Ion Beam Mixing of Ni Overlayers on Sintered Alpha-SiC.- Structure-Property Relations in Multiphase Ceramics.- Quantitative Microstructural Characterization and Description of Multiphase Ceramics.- Displacive Transformation Mechanisms in Zirconia Ceramics and Other Non-Metals.- On Precipitate Morphology in ZrO2 ?-Al2O3, FeTiO3 Matrices.- Particle Toughening in Partially Stabilized Zirconia Influence of Thermal History.- Fabrication and Properties of Transformation-Toughened Sodium Beta"-Alumina.- Phase Transformation and Toughening in MgO Dispersed with ZrO2.- Effect of Impurities on Microstructure and Mechanical Properties of Si3N4-TiC Composites.- On the Microstructure and Hardness Characteristics of Composite Ceramics for Tool Applications.- Mechanical Properties and Wear Resistance of Silicon Nitride-Titanium Carbide Composites.- The Structure and Properties of Interfaces in Reaction-Bonded Silicon Carbides.- Some Factors Affecting Mechanical and Microstructural Anisotropy in Reaction-Bonded Silicon Carbides.- Microstructure-Mechanical Property Relationships in 94% Alumina Ceramics.- New Low Expansion Magnetic Materials-A Composite Approach.- Multiphase Electroceramics.- Electroceramic Composites.- Finite Element/Difference Modeling of Electroceramics.- Multiphase Interaction for Seeking Exotic Phenomena.- Processing of Heterogeneous Ceramics for Dielectric Applications.- Dielectric and Electrical Properties of BaTiO3 Composites.- Composite Piezoelectric Sensors.- Wave Absorption in Piezoceramic-Polymer Composites.- Structured Macrovoids in Ceramic PZT.- Composite Thermistors.- Grain Resistivity and Conduction in Metal Oxide Varistors.- Influence of Microstructure and Chemistry on the Electrical Characteristic of ZnO Varistors.- Influence of Chemical Composition on the Barrier Height in Zn Varistors.- Polycrystalline H3O+-?/?" Alumina: A Designed Composite for Steam Electrolysis.- Fiber and Whisker Reinforced Composites.- The Development of Fiber Reinforced Glasses and Glass Ceramics.- Interfacial Characterization of Glass and Glass-Ceramic Matrix/Nicalon SiC Fiber Composites.- Fatigue Behavior of Silicon Carbide Fiber Reinforced Lithium-Alumino-Silicate Glass-Ceramics.- Fiber Reinforced Composites Via the Sol/Gel Route.- Fiber-Matrix Interactions in Carbon Fiber/Cement Matrix Composites.- Morphological and Mechanical Characterization of Ceramic Composite Materials.- Toughness Anisotropy of a SiC/SiC Laminar Composite.- Whisker Reinforced Ceramic Composites.- Whisker-Reinforced Zirconia-Toughened Ceramics.- Si3N4-SiC Whisker Composite Material.- Mechanical Properties of SiC Fiber-Reinforced Reaction-Bonded Si3N4 Composites.- Surface Energy as an Indicator of Interfacial Mechanical Response.- High Temperature Multiphase Ceramics.- Prospects for Ultra-High-Temperature Ceramic Composites.- Microstructural Engineering of Ceramics for High-Temperature Application.- Tailoring of the Thermal Transport Properties and Thermal Shock Resistance of Structural Ceramics.- Creep Rupture of Siliconized Silicon Carbide.- High Temperature Mechanical Properties of Siliconized Silicon Carbide Composites.- Contributors.

192 citations


Journal ArticleDOI
TL;DR: In this article, a wide range of microstructures in A533B pressure-vessel steel was studied to explore the relationship between microstructural parameters and toughness, as characterized by both the critical stress intensity factor, KIC, and the microscopic (local) cleavage fracture stress, σF∗.

178 citations


Journal ArticleDOI
TL;DR: In this article, a dynamic calculation involving the formation of a non-equilibrium crack in the carbide is used to explain the experimental observations, which indicates a grain size dependence.

156 citations


Patent
19 May 1986
TL;DR: In this article, an earth boring apparatus is disclosed having bearing members comprised of transition layer polycrystalline diamond, which act as the bearing surface and are supported by a cemented tungsten carbide substrate interfaced with the transition layer.
Abstract: An earth boring apparatus is disclosed having bearing members comprised of transition layer polycrystalline diamond. The transition layer polycrystalline diamond bearings include a polycrystalline diamond layer interfaced with a composite transition layer comprising a mixture of diamond crystals and precemented carbide pieces subjected to high temperature/high pressure conditions so as to form polycrystalline diamond material bonded to the precemented carbide pieces. The polycrystalline diamond layer acts as the bearing surface. The transition layer bearings are preferably supported by a cemented tungsten carbide substrate interfaced with the transition layer.

140 citations


Journal Article
TL;DR: In this paper, the nature and composition of the surfaces of silicon nitride and silicon carbide powders were investigated using high voltage and high resolution transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and secondary ion mass spectrometry (SIMS).
Abstract: The nature and composition of the surfaces of silicon nitride and silicon carbide powders were investigated using high voltage and high resolution transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and secondary ion mass spectrometry (SIMS). An amorphous oxide (or oxygen-rich) layer, approx. =3-5 nm thick, present on the powder surfaces forms strong bridges between particles. Both XPS and SIMS show that oxygen is the major impurity on the powder surfaces, but minor impurities such as chlorine, fluorine, carbon, iron and sodium are also revealed. The extent of the oxide layer was reduced substantially by washing the powder in anhydrous hydrofluoric acid or by treatment in an argon/hydrogen gas mixture at approx. =1300/sup 0/C. Surface treatment in the gas mixture did not cause further agglomeration of the powder.

115 citations


Patent
James W. Warren1
07 Oct 1986
TL;DR: In this article, a method of composite article and a composite article specifically adapted for use in high temperature, corrosive and errosive environments comprising a carbon fibrous substrate, including a pyrolytic carbon sheath formed about each fiber of the substrate; a metallic carbide, oxide, or nitride compliant coating over the coated fibers of the substrates; and an impermeable metallic carbides, oxide or nitric outer protective layer formed about the entire periphery of the coated substrate.
Abstract: A method of making a composite article and a composite article specifically adapted for use in high temperature, corrosive and errosive environments comprising a carbon fibrous substrate, including a pyrolytic carbon sheath formed about each fiber of the substrate; a metallic carbide, oxide, or nitride compliant coating over the coated fibers of the substrate; and an impermeable metallic carbide, oxide or nitride outer protective layer formed about the entire periphery of the coated substrate. In accordance with the method of the invention, the compliant metallic coating is applied to the fibers in a manner such that any mechanical stresses built-up in the substrate due to a mismatch between the coefficient of thermal expansion of the fibrous substrate and the coating are effectively accomodated.

113 citations


Patent
Subhash K. Naik1, Louis J. Fiedler1
20 May 1986
TL;DR: In this paper, the authors defined the content of either the carbide, nitride, boride or oxide of a metal selected from Group III to Group VI elements, the first layer capable of retaining substrate integrity and preventing diffusion of material from the second layer into the substrate.
Abstract: Erosion resistance is imparted to a metallic substrate without an attendant loss of fatigue life in the substrate in one embodiment by applying to the substrate a first ductile layer comprising a metal from Group VI to Group VIII elements as well as the noble metal group of elements, and a second hard erosion-resistant layer applied on the first layer comprising a boride, carbide, nitride or oxide of a metal selected from Group III to Group VI elements, the first layer capable of retaining substrate integrity and preventing diffusion of material from the second layer into the substrate. Another embodiment defines another layer of a substantially pure metal from Group III to Group VI between the first and second layers. Still another embodiment defines that in the second layer the content of either the carbide, nitride, boride or oxide is graded, i.e. the concentration of either the carbide, nitride, boride or oxide is greatest (higher) toward the top surface of the second layer, and decreases toward the bonding surface between the second and first layer.

109 citations


Journal ArticleDOI
TL;DR: Corrosion of sintered alpha-SiC under thin films of Na2CO3/CO2, Na2SO4/O2, and Na2 SO4/SO3 was investigated at 1000 C as mentioned in this paper.
Abstract: Corrosion of sintered alpha-SiC under thin films of Na2CO3/CO2, Na2SO4/O2, and Na2SO4/SO3 was investigated at 1000 C. Chemical analysis was used to follow silicate and silica evolution as a function of time. This information coupled with morphology observations leads to a detailed corrosion mechanism. In all cases the corrosion reactions occur primarily in the first few hours. In the Na2CO3/CO2 case, rapid oxidation and dissolution lead to a thick layer of silicate melt in about 0.25 h. After this, silica forms a protective layer on the carbide. In the Na2SO4/O2 case, a similar mechanism occurs. In the Na2SO4/SO3 case, a porous nonprotective layer of SiO2 grows directly on the carbide, and a silicate melt forms above this. In addition, SiO2 and regenerated Na2SO4 form at the melt/gas interface due to reaction of silicate with SO3 and SO2 + O2. The reaction slows when the lower silica layer becomes nonporous.

96 citations


Journal ArticleDOI
TL;DR: In this article, a study of the preparation of carbides using hydrous oxide precursors is presented, where two different precurors (WO3 · H2O and hexagonal WO3· xH2O), obtained by homogeneous precipitation from ammonium tungstate solutions, are converted into carbides after preliminary dehydration and reduction steps.

Journal ArticleDOI
TL;DR: Carbide/carbide boundaries in WC-Co-base cemented carbides containing 6-20 wt-%Co were studied with two high resolution microanalytical techniques: atom probe field ion microscopy and analytical transmission electron microscopy as discussed by the authors.
Abstract: Carbide/carbide boundaries in WC–Co-base cemented carbides containing 6–20 wt-%Co were studied with two high resolution microanalytical techniques: atom probe field ion microscopy and analytical transmission electron microscopy. All boundaries studied, i.e. WC/WC boundaries and, in materials containing cubic carbides (γ-phase), WC/γ and γ/γ boundaries, were found to contain about half a monolayer of cobalt, localized to a zone of monolayer thickness. The carbide/carbide boundaries may thus be described as grain (phase) boundaries to which cobalt has segregated. The carbide skeleton model for WC–Co is thereby confirmed. In WC–Co materials which contain Cr3C2 as a grain growth inhibitor, chromium segregates to WC grain boundaries.MST/354

Journal ArticleDOI
TL;DR: In this paper, a comparison of calculated and experimental values of the characteristic mass, mXXX for 40 elements atomized in standard graphite tubes using integrated absorbance signals was made, and the results obtained support the possibility of developing an absolute method of AA analysis based on the STPF technique.

Journal ArticleDOI
TL;DR: In this paper, the crystal structures of DyCoC2 and DyNiC2 were refined from singlecrystal X-ray data to residuals of R = 0.012 (581 structure factors) and R =0.023 (971 structure factors), for 17 variable parameters.
Abstract: 32 carbides RTC2 (R ≡ rare earth metal, T ≡ Fe, Co, Ni), 18 for the first time, were prepared by arc melting of the elemental components and subsequent annealing in evacuated silica tubes. Most of them crystallize in the orthorhombic CeNiC2-type structure. The carbides LnCoC2 (Ln ≡ La, Ce, Pr, Nd) have the related monoclinic CeCoC2-type structure. SmCoC2 is of CeCoC2 type at low temperature and of CeNiC2 type at high temperature. The crystal structures of DyCoC2 and DyNiC2 were refined from singlecrystal X-ray data to residuals of R = 0.012 (581 structure factors) and R = 0.023 (971 structure factors) for 17 variable parameters. The carbon atoms in these compounds form pairs. The C-C distances of 1.37 A come close to the double bond distances of 1.34 A in alkenes. The hydrolysis of DyCoC2 in diluted hydrochloric acid, however, yields only little ethene, mainly ethane and some propane and methane. The cell volumes indicate that cerium and ytterbium are essentially trivalent in these compounds, whereas the corresponding europium compounds cannot be prepared under similar conditions.

Patent
17 Jun 1986
TL;DR: In this paper, a chemical pretreatment method is used to produce boron carbide-, bororon-, and boride-reactive metal composites by an infiltration process, where starting constituents are immersed in various alcohols, or other chemical agents, to change the surface chemistry of the starting constituents.
Abstract: A chemical pretreatment method is used to produce boron carbide-, boron-, and boride-reactive metal composites by an infiltration process. The boron carbide or other starting constituents, in powder form, are immersed in various alcohols, or other chemical agents, to change the surface chemistry of the starting constituents. The chemically treated starting constituents are consolidated into a porous ceramic precursor which is then infiltrated by molten aluminum or other metal by heating to wetting conditions. Chemical treatment of the starting constituents allows infiltration to full density. The infiltrated precursor is further heat treated to produce a tailorable microstructure. The process at low cost produces composites with improved characteristics, including increased toughness, strength.

Journal ArticleDOI
TL;DR: In this article, the authors evaluated the hardness of different types of nitride and carbide coatings and found that ZrC was the hardest carbide with a hardness of 4840 kg/mm2.
Abstract: TiN, TiC, ZrN, ZrC, HfN, and HfC coatings were reactively sputtered at high rates of 2300 –5800 A/min onto T‐15 high speed steel cutting tool inserts. Nitrogen was controlled through closed loop peak feedback control for the preparation of the nitride coatings, but either peak feedback control or flow control could be used for the carbide coatings. Methane was the reactive gas for TiC and ZrC, but it led to macrovoids in HfC. Acetylene produced dense HfC coatings. All of these coatings are much harder than the values for the bulk materials. Hafnium nitride was the hardest nitride with a Vickers microhardness (50 g) of 4690 kg/mm2, whereas ZrC was the hardest carbide with a hardness of 4840 kg/mm2. Except for TiC, all of the coatings have a lattice parameter that is greater than the bulk value. The coatings have the NaCl structure with a (111) preferred orientation. All of the coatings have an excellent adhesion to the T‐15 substrates, but a ZrN/Zr carbonitride interface was necessary with ZrC to obtain go...

Patent
25 Jul 1986
TL;DR: In this article, a low-density boron carbide-aluminum composites with a homogeneous microstructure possessing desired mechanical properties are produced. But the composites do not have the same properties as the high-density composites.
Abstract: Low-density composites are produced consisting chiefly of boron carbide and aluminum, or aluminum alloy, and minor amounts of ceramic material. The method allows control of the rate of reaction between boron carbide and metal so that the final components of the composite, and hence the mechanical properties, are controlled. The invention includes modification of the carbon content of the boron carbide composition, dispersion of boron carbide and formation of a compact, infiltration of the compact by aluminum or aluminum alloy, and heat treatments. The invention produces low-density boron carbide-aluminum composites with a homogeneous microstructure possessing desired mechanical properties.

Journal ArticleDOI
TL;DR: In this paper, the activation energy of ZrC hot-pressing was calculated, starting from the viscosity calculated by Murray's formula, as 41 kcal mol−1 (171.7 kJmol−1).
Abstract: The hot-pressing kinetics of zirconium carbide were studied between 1700 and 2400° C in argon. The validity of different theoretical models due to Murray, Koval'chenko, Skorokhod, Scholz and Lersmacher was tested. For temperatures exceeding 2200° C, there is reasonably good agreement between kinetics and the whole set of models, but it has not been possible to classify them in order to draw conclusions on the sintering mechanism. The activation energy of ZrC hot-pressing was calculated, starting from the viscosity calculated by Murray's formula, as 41 kcal mol−1 (171.7 kJ mol−1).

Journal ArticleDOI
TL;DR: In this paper, the microstructure and phase chemistry of a Fe-34Cr-4.5C wt% hardfacing alloy have been investigated using transmission electron microscopy and microanalytical techniques.
Abstract: The microstructure and phase chemistry of a Fe-34Cr-4.5C wt% hardfacing alloy has been investigated using transmission electron microscopy and microanalytical techniques. The microstructure is found to consist of large primary M7C3. carbides in a eutectic mixture of austenite and more M7C3. The results indicate that the microstructure of the undiluted alloy becomes configurationally frozen at a temperature of about 1150° C during deposition by the manual metal arc welding technique. This allows the metastable austenite phase to contain a large chromium concentration (≈ 16 to 17 wt %), thus imparting good corrosion and oxidation resistance. Experimental data on the partitioning of chromium, manganese and silicon between the carbide phases are discussed in the context of the high-temperature stability of the alloy.

Patent
18 Dec 1986
TL;DR: In this article, a method for welding metal composite materials, including metal-ceramic composites, whereby a weld or filler material is prepared by the in-situ precipitation of ceramic in a metallic matrix is described.
Abstract: A method for welding metal composite materials, including metal-ceramic composites, whereby a weld or filler material is prepared by the in-situ precipitation of ceramic in a metallic matrix The filler material may comprise boride, carbide, oxide, nitride, silicide, etc, while the matrix metal may constitute a alloy or intermetallic of two or more metals A strong bond is achieved when welding two conventional metals, a conventional metal and a metal-ceramic composite, or two metal-ceramic composites

Journal ArticleDOI
TL;DR: In this article, it was shown that aluminum layers of some nanometers thickness have been deposited onto α-SiC crystals and studied by x-ray and ultraviolet photoelectron spectroscopies as a function of annealing temperature.
Abstract: Aluminum layers of some nanometers thickness have been deposited onto α‐SiC crystals and studied by x‐ray and ultraviolet photoelectron spectroscopies as a function of annealing temperature. Annealing beyond 600 °C induces a complete disappearance of metallic Al on the crystal surface, penetration of Al into the bulk, and formation of aluminum carbide. Ultraviolet photoemission spectra recorded after annealing at 360 °C could be explained by a beginning of interfacial reaction. However, there is no clear experimental evidence that reaction occurs at such a low temperature.

Patent
19 Dec 1986
TL;DR: A steel roughing grade coated cemented carbide cutting tool comprises WC grains equal to or less than 70 w/o of the tool substrate and the remainder being metal carbide grains selected from the group TiC, TaC, NbC, HfC and combinations thereof as mentioned in this paper.
Abstract: A steel roughing grade coated cemented carbide cutting tool comprises WC grains equal to or less than 70 w/o of the tool substrate, from about 5 to about 10 w/o of a cobalt bonding phase and the remainder being metal carbide grains selected from the group TiC, TaC, NbC, HfC and combinations thereof. The average WC grain size is from about 0.9 to about 1.3 microns and less than 10% of the WC grains have a size less than 0.5 microns. The coated cemented carbide tool is coated with an adherent refractory coating layer. The coated cemented carbide cutting tool can be used to machine steel at rough and heavy rough cutting conditions.

Journal ArticleDOI
TL;DR: In this paper, the interaction of boron carbide and silicon carbide with liquid aluminium at 1000 K was studied when the melt was not stirred, and the results were compared with those obtained using quantitative chemical analysis for B4C and aluminium carbide.
Abstract: The interaction of boron carbide and silicon carbide with liquid aluminium at 1000 K was studied when the melt was not stirred. Electron and X-ray diffraction methods were used to identify Al4C3 and AlB2 phases in the Al-B4C system, while the Al4C3 phase only was identified in the Al-SiC system. All the phases were found to grow when the metal crystallized from the supersaturated solution in the shape of rectilinearly faceted crystals. By weighing the specimens prior to and following contact with the liquid metal, kinetic peculiarities of the dissolution of carbide were established. Constants of boron and carbon dissolution from carbides in liquid aluminium were determined. The results are compared with those obtained using quantitative chemical analysis for boron carbide and aluminium carbide. The higher dissolution rate of boron carbide as compared with that of silicon carbide is accounted for by the peculiar structure of the solid.

Journal ArticleDOI
TL;DR: The ductile fracture characteristics of a commercial 9 Cr-1 Mo steel have been studied using tensile specimens of the material, both in the normalised and tempered condition and after ageing.

Journal ArticleDOI
TL;DR: In this paper, the effects of aging treatments on the stress corrosion cracking behavior of Fe8.7Al-29.7Mn-1.04C alloy is discussed.

Journal ArticleDOI
TL;DR: In this paper, the effect of carbon in different states of dispersion has been examined in relation to its effect on the texture formed during the annealing of cold-rolled steel sheet.
Abstract: The effect of carbon in different states of dispersion has been examined in relation to its effect on the texture formed during the annealing of cold-rolled steel sheet. Quantitative texture analyses using orientation distribution functions have been combined with detailed metallographic investigation of changes taking place during recrystallization. Calculations have also been carried out on the rate of dissolution of carbon from cementite particles for a range of relevant conditions. Dissolved carbon present before cold rolling greatly reduces the final annealed {111} texture strength and leads instead to a spread around the Goss orientation. Dissolved carbon present with manganese during annealing also reduces the final {111} intensity, tending to replace it with a number of relatively weak minor components; this is observed during conditions of slow heating, or when primary carbide particles are numerous, and seems to be associated with a significant nucleation rate of new grains during the la...

Journal ArticleDOI
TL;DR: In this article, a mechanistic model of the tool wear process has been presented that includes the effects of both the abrasion of a tool material by inclusions within the workpiece and the chemical dissolution of the material into the matrix of a workpiece.
Abstract: A mechanistic model of the tool wear process has been presented [B. M. Kramer and P. K. Judd, J. Vac. Sci. Technol. A 3, 2439 (1985)] that includes the effects of both the abrasion of the tool material by inclusions within the workpiece and the chemical dissolution of the tool material into the matrix of the workpiece. Machining tests have been run on steel with titanium carbide coated tooling and the resulting test data have been employed to produce a rough calibration of the proposed model. This model has been used to predict the wear resistances of the other group IV B carbides and of the (Ti,Hf)C system in the machining of steel.

Patent
01 May 1986
TL;DR: In this paper, the silicon carbide particulate reinforced aluminum alloy matrix composites are formed using techniques which include agitation of a melt of aluminum alloy, containing magnesium, and silicon carbides particulates in a manner whereby the carbide particles are maintained, during agitation, within the body of the melt; the agitation, which involves shearing or wiping of the particles in the liquid, is carried out under vacuum.
Abstract: Silicon carbide particulate reinforced aluminum alloy matrix composites are formed using techniques which include agitation of a melt of aluminum alloy, containing magnesium, and silicon carbide particulates in a manner whereby the silicon carbide particles are maintained, during agitation, within the body of the melt; the agitation, which involves shearing or wiping of the particles in the liquid, is carried out under vacuum; and may involve incorporation into the melt of an additional amount of magnesium such that that amount compensates for the amount of magnesium which segregates to the carbide surfaces, and is sufficient to effect strengthening of the resulting composite. Aluminum alloy matrix composites, containing copper, are produced using similar agitation and mixing procedures, with the copper being incorporated in such a way as to discourage reaction between the copper and SiC particles.

Journal ArticleDOI
TL;DR: In this article, the effect of hard coatings on the cutting edge of a fly-cutter was examined under a nominal range of cutting conditions and optical and electron microscopy showed both thermal fatigue-induced vertical cracks and lateral cracks parallel to the edge.
Abstract: The role of hard coatings in prolonging the life of cemented carbide tools is now well‐documented for continuous turning applications. In contrast, relatively few studies have elucidated the effect of such coatings in milling, where both mechanical and thermal cyclic loading impose special requirements on the tool cutting edge. This investigation describes the wear mechanisms observed in coated carbide milling tools which have been the object of recent commercial tool development. Coated carbide tools (by CVD and PVD) of varying cutting edge geometry, substrate, and coating composition were subjected to fly‐cutter milling tests under a nominal range of cutting conditions. Examination of the used cutting edges under optical and electron microscopy showed both thermal‐fatigue‐induced vertical cracks, perpendicular to the cutting edge, as well as lateral cracks parallel to the edge which result from mechanical cyclic stresses. The wear patterns and the sequential progression of these cracks were characterize...