Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C29/00—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides
  • C22C29/12—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides based on oxides
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
  • B22F1/18—Non-metallic particles coated with metal
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C19/00—Alloys based on nickel or cobalt
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C33/00—Making ferrous alloys
  • C22C33/02—Making ferrous alloys by powder metallurgy
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C47/00—Making alloys containing metallic or non-metallic fibres or filaments
  • C22C47/02—Pretreatment of the fibres or filaments
  • C22C47/04—Pretreatment of the fibres or filaments by coating, e.g. with a protective or activated covering
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C49/00—Alloys containing metallic or non-metallic fibres or filaments
  • C22C49/02—Alloys containing metallic or non-metallic fibres or filaments characterised by the matrix material
  • C22C49/08—Iron group metals
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C49/00—Alloys containing metallic or non-metallic fibres or filaments
  • C22C49/14—Alloys containing metallic or non-metallic fibres or filaments characterised by the fibres or filaments

Definitions

• the present invention relates to a ceramic-metallic composite material based on aluminum oxide and to a process for the manufacture of this material.
• Aluminum oxide has the characteristics of excellent wear resistance. This material is used in cutting tools for metals or for wear-resistant surfaces.
• Aluminum oxide in the form of a coating on conventional carbide tools is formed by vapor deposition or by sputtering. It is known that the mechanical properties of aluminum oxide can be improved by forming solid solutions with other oxides such as chromium oxide, or by forming multiphase compositions with other oxides such as that of zirconium. . In addition, it is known to form cutting tools by sintering or by a hot pressing process.
• Aluminum oxide compositions may also include additives for fixing the grain boundaries, such as magnesium oxide, titanium oxide or titanium carbide.
• Aluminum oxide tools are too fragile for most steel cutting operations, and their use is limited to finishing cuts, due to their lack of ductility leading to an inability to resist loads or vibrations even averages between the tool and the workpiece without risk of breakage. Tests have been carried out to produce ceramic-metallic materials based on aluminum oxide for cutting tools, so far with very little success, this because of the difficulty of bonding aluminum oxide to metals. Thus, previous attempts to significantly increase the breaking strength of composite materials have not been successful.
• the object of the present invention therefore consists in completely eliminating the interfacial oxide phases and thus in increasing the tensile strength.
• the ceramic-metallic composite material according to the present invention aimed at achieving the goal mentioned above, has the characteristics mentioned in claim 1.
• the second phase or matrix preferably containing approximately 20% by weight of additional ingredients in addition to the metal and the titanium carbide, is therefore made non-reactive with respect to aluminum oxide by inclusion of a sufficient amount of titanium carbide at the interface between the aluminum oxide and this matrix, in order to prevent any chemical reaction at this interface between this matrix and the aluminum oxide particles, during the phase of consolidation at liquidus temperature, i.e. at sintering temperature.
• the structure obtained is characterized by the absence of brittle or weak resistance interfacial phase and by the absence of an interface consisting of reaction compounds such as oxides.
• the composite material according to the invention contains an amount of less than about 30% by volume of the matrix metal phase, and more particularly it contains between about 70 and 90% by volume of aluminum oxide.
• the material according to the invention is also useful for the manufacture of structural parts having good resistance to abrasion and to chemical wear, including to oxidation, and then contains the metallic phase in a concentration up to approximately 40% by volume, more particularly it contains between approximately 50 and 70% by volume of aluminum oxide.
• Another object of the present invention consists of a process for the manufacture of the ceremonial-metallic composite material defined above, which has the characteristics mentioned in the Claim 12.
• the sintering reaction of the constituent elements is therefore carried out by controlling the partial pressure of carbon monoxide, and preferably in a non-oxidizing atmosphere, for example under vacuum or under an inert atmosphere. It can be combined with hot pressing or with isostatic hot pressing.
• all the parts of titanium carbide present at the interface can be provided by coating the aluminum oxide component in the form of particles with titanium carbide, before the phase of consolidation of the particles by sintering. for the formation of an article.
• the material according to the invention is prepared by consolidation or sintering of a mixture of microscopic homogeneous powders with an aluminum oxide and / or of a solid solution containing one or more constituents of aluminum oxide and (b) a matrix phase.
• This matrix phase comprises a metal capable of retaining relatively high concentrations of titanium and carbon and a source of titanium and carbon.
• the relative concentrations of titanium and carbon should be such that they can form titanium carbide in an amount sufficient to prevent reaction at the interface between the matrix phase and the aluminum oxide phase. Such a reaction must be eliminated, since it results in the formation of interface compositions which may be harmful.
• Suitable temperatures for consolidation by sintering the homogeneous mixture to form an article are between the minimum temperature at which the metallic component forms a liquid with the appropriate concentration of titanium and carbon up to the temperature of the melting point of aluminum oxide. Preferably, this temperature is between approximately 1300 and approximately 1600 ° C.
• the mixture is subjected to an elevated temperature for a period sufficient for the titanium and carbon constituents to dissolve in the metal matrix, so that the titanium and carbon are retained in this matrix in the form of a liquid solution. It is believed that the presence of titanium carbide at the interface delays or prevents a reaction at the interface of the metal matrix and aluminum oxide.
• compositions prepared by the process according to the invention contain between approximately 70 and 90% by volume of aluminum oxide.
• the composite material according to the present invention contains more than about 50% by volume. aluminum oxide, preferably between about 50 and 70% by volume.
• Al2O3 + 3TiC Al4C3 + 3 TiO2
• Al2O3 + 3 TiC 5 (Al 0.4 Ti 0.6 ) + 3CO ⁇
• Al2O3 + (a + y) TiC Al x Ti y + Ti a O b + (a + y) CO ⁇ (3)
• b [1.5 x - (a + y)]
• the partial pressure of CO during sintering is maintained in a range of about 10 ⁇ 5 to 10 ⁇ 2 Torr (1.33.10 ⁇ 3 to 1.33 Pa), and preferably about 10 ⁇ 4 to 10 ⁇ 3 Torr (1.33.10 ⁇ 2 to 1, 33.10 ⁇ 1 Pa).
• the composite material according to the invention is characterized by a microstructure which is substantially composed of a ceramic phase of aluminum oxide separated and agglomerated by a ductile metallic matrix phase.
• the interface between the aluminum oxide phase and the metallic matrix phase is mainly composed of titanium carbide.
• This composite material has a breaking strength (or stress intensity factor K IC ) of 8 to 15 MN / m3 / 2, therefore much higher in comparison with the 4 to 5 MN / m3 / 2 of the compositions based commercially available alumina.
• the various constituents intended to form the composite material according to the invention are mixed and ground by techniques such as ball milling, air milling, or the like, before subjecting the mixture to a temperature and a pressure. high.
• Representative sources of titanium are metallic titanium and titanium carbide.
• Representative sources of carbon are carbon, as well as titanium carbides, molybdenum, tungsten, vanadium, carbide, chromium, tantalum, niobium, zirconium, and hafnium.
• the first suitable metal components which are relatively non-reactive by compared to aluminum oxide, titanium and titanium carbide, include nickel, iron, cobalt or mixtures thereof.
• the solubility of titanium and carbon in the metallic matrix phase can be increased by adding a third component in an amount generally between about 5 and 30% by weight, relative to the weight of said first metallic component, such as carbide molybdenum, tungsten carbide, vanadium carbide, ruthenium, rhodium, rhenium and osmium.
• a third component such as carbide molybdenum, tungsten carbide, vanadium carbide, ruthenium, rhodium, rhenium and osmium.
• any available form of aluminum can be used in the present invention, including a powder of particles between about 0.1 and 100 microns in diameter, wiskers, fibers or other solid forms.
• the present invention can also be used to bond solid aluminum oxide components to each other or to metallic components.
• the aluminum oxide particles are pre-coated with titanium carbide, titanium oxicarbons or titanium, before being mixed with the metallic matrix phase.
• Suitable coating techniques include chemical vapor deposition, simple or combined with plasma or laser technique, sputtering, physical vapor deposition, vacuum evaporation or reduction of titanium oxide coating on the surface of the aluminum oxide particles.
• the above-mentioned coating methods can be carried out in a reaction chamber which is surrounded by an induction coil electrically connected to a frequency oscillator radio.
• the chamber is provided with inlets and outlets at its axial ends for the flow of the gaseous medium.
• the untreated powder is placed in the reaction chamber and subjected to the desired coating temperatures by use of the radio frequency oscillator.
• titanium carbide layers are formed on aluminum oxide particles in the reaction chamber by entraining the particles in a gaseous mixture of titanium tetrachloride, from a source of carbon gas, such as than methane, and hydrogen, and by heating the particles to a temperature between about 800 and about 1800 ° C, preferably around 1000 ° C.
• the reaction can be described by the following equation, although hydrogen is often added to ensure that the reaction takes place in a reducing environment: TiCl4 + CH4 ⁇ TiC + 4 HCl ⁇
• the mixture containing the particles is kept at the reaction temperature until the desired coating thickness is obtained.
• a routine test is carried out to determine the value of the growth in thickness of the coating at a particular value of the gas flow rate and at a determined temperature.
• Typical preferred coatings are on the order of 100 to 1,000 angstroms, and preferably 200 to 500 angstroms.
• Alumina powders were placed in pyrex glass tubes for chromatography having a tapered end to which a porous sintered glass plate has been attached. Argon was introduced into the tubes and passed through the sintered glass and the powder bed. By precisely controlling the gas flow, by means of a micrometric valve, only fine particles were entrained in the gas stream and introduced into the reaction chamber either at the bottom of it in the gas inlet or directly in plasma by attaching an elongated alumina tube to the normal gas and powder inlet. The powder was collected by reducing the speed of the gas stream in an enlarged chamber and by filtering the gas through stainless steel filters. After the generator was operated at full power, argon was introduced into the reaction chamber until a flow rate of 750 ml / min was obtained.
• the gas mixture of TiCl4 + CH4 + H2 was introduced.
• argon gas was slowly introduced through the powder bed. Then the gas flow was increased until it can be seen that fine powder leaves the fluidization chamber and enters the plasma chamber.
• the powders were ground for 24 hours in containers containing about 1.3 cm alumina beads as a means of grinding.
• the powder mixtures were then placed in a mold and pressed uniaxially at around 100 Kpsi (700 MPa) to form compact samples.
• These compact samples were sintered under vacuum for one hour at 1370 ° C.
• the sintered samples based on alumina were encapsulated in steel containers and isostatically pressed at 45 Kpsi (310MPa) and 1370 ° C for samples 1 and 4, and at 35 Kpsi (242MPa) and at 1315 ° C for samples 2,3,5 and 6. These samples thus treated were cut by means of diamond blades, polished and mounted so as to examine their microstructure.
• compositions 1, 2 and 3 the alumina phase is aggregated and continuous, and the metal phase is distributed in pockets isolated by the alumina phase, indicating that the incomplete wetting results in apparent sintering in the solid state of the powders. alumina.
• the alumina phase is surrounded by the metal phase which appears to be continuous.
• the size distribution of the alumina particles appears to be similar, but the TiC coated alumina particles are more uniformly dispersed in the metal binder than the uncoated alumina particles.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Compositions Of Oxide Ceramics (AREA)
• Manufacture Of Alloys Or Alloy Compounds (AREA)

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• 1986
  • 1986-10-10 US US06/917,577 patent/US4792353A/en not_active Expired - Lifetime
• 1987
  • 1987-09-30 DE DE198787114248T patent/DE263427T1/de active Pending
  • 1987-09-30 ES ES87114248T patent/ES2002692A4/es active Pending
  • 1987-09-30 EP EP87114248A patent/EP0263427B1/de not_active Expired - Lifetime
  • 1987-09-30 DE DE8787114248T patent/DE3786976D1/de not_active Expired - Lifetime
  • 1987-09-30 AT AT87114248T patent/ATE92971T1/de not_active IP Right Cessation
  • 1987-10-09 JP JP62253943A patent/JPS63134644A/ja active Pending

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