US3177084A - Method of making carbide-coated graphite dies and coated article - Google Patents
Method of making carbide-coated graphite dies and coated article Download PDFInfo
- Publication number
- US3177084A US3177084A US104466A US10446661A US3177084A US 3177084 A US3177084 A US 3177084A US 104466 A US104466 A US 104466A US 10446661 A US10446661 A US 10446661A US 3177084 A US3177084 A US 3177084A
- Authority
- US
- United States
- Prior art keywords
- die
- carbide
- titanium
- film
- hydrogen
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 title claims description 32
- 229910002804 graphite Inorganic materials 0.000 title claims description 28
- 239000010439 graphite Substances 0.000 title claims description 28
- 238000004519 manufacturing process Methods 0.000 title description 5
- 239000011248 coating agent Substances 0.000 claims description 24
- 238000000576 coating method Methods 0.000 claims description 24
- 238000007731 hot pressing Methods 0.000 claims description 21
- 238000000034 method Methods 0.000 claims description 19
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims description 5
- 239000010936 titanium Substances 0.000 claims description 5
- 229910052719 titanium Inorganic materials 0.000 claims description 5
- QCWXUUIWCKQGHC-UHFFFAOYSA-N Zirconium Chemical compound [Zr] QCWXUUIWCKQGHC-UHFFFAOYSA-N 0.000 claims description 4
- 229910052726 zirconium Inorganic materials 0.000 claims description 4
- 229910052735 hafnium Inorganic materials 0.000 claims description 3
- VBJZVLUMGGDVMO-UHFFFAOYSA-N hafnium atom Chemical compound [Hf] VBJZVLUMGGDVMO-UHFFFAOYSA-N 0.000 claims description 3
- 229910052758 niobium Inorganic materials 0.000 claims description 3
- 239000010955 niobium Substances 0.000 claims description 3
- GUCVJGMIXFAOAE-UHFFFAOYSA-N niobium atom Chemical compound [Nb] GUCVJGMIXFAOAE-UHFFFAOYSA-N 0.000 claims description 3
- 229910052715 tantalum Inorganic materials 0.000 claims description 3
- GUVRBAGPIYLISA-UHFFFAOYSA-N tantalum atom Chemical compound [Ta] GUVRBAGPIYLISA-UHFFFAOYSA-N 0.000 claims description 3
- 229910052720 vanadium Inorganic materials 0.000 claims description 3
- LEONUFNNVUYDNQ-UHFFFAOYSA-N vanadium atom Chemical compound [V] LEONUFNNVUYDNQ-UHFFFAOYSA-N 0.000 claims description 3
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 25
- 239000001257 hydrogen Substances 0.000 description 25
- 229910052739 hydrogen Inorganic materials 0.000 description 25
- 230000007704 transition Effects 0.000 description 22
- MTPVUVINMAGMJL-UHFFFAOYSA-N trimethyl(1,1,2,2,2-pentafluoroethyl)silane Chemical compound C[Si](C)(C)C(F)(F)C(F)(F)F MTPVUVINMAGMJL-UHFFFAOYSA-N 0.000 description 20
- 239000000843 powder Substances 0.000 description 14
- QYEXBYZXHDUPRC-UHFFFAOYSA-N B#[Ti]#B Chemical compound B#[Ti]#B QYEXBYZXHDUPRC-UHFFFAOYSA-N 0.000 description 12
- 229910033181 TiB2 Inorganic materials 0.000 description 12
- XJDNKRIXUMDJCW-UHFFFAOYSA-J titanium tetrachloride Chemical compound Cl[Ti](Cl)(Cl)Cl XJDNKRIXUMDJCW-UHFFFAOYSA-J 0.000 description 11
- 125000002915 carbonyl group Chemical group [*:2]C([*:1])=O 0.000 description 8
- 239000000463 material Substances 0.000 description 8
- 239000000203 mixture Substances 0.000 description 8
- 238000003825 pressing Methods 0.000 description 8
- 239000002002 slurry Substances 0.000 description 8
- 239000008246 gaseous mixture Substances 0.000 description 6
- 238000010438 heat treatment Methods 0.000 description 6
- 230000001681 protective effect Effects 0.000 description 6
- KPZGRMZPZLOPBS-UHFFFAOYSA-N 1,3-dichloro-2,2-bis(chloromethyl)propane Chemical compound ClCC(CCl)(CCl)CCl KPZGRMZPZLOPBS-UHFFFAOYSA-N 0.000 description 5
- 238000010304 firing Methods 0.000 description 5
- 239000003973 paint Substances 0.000 description 5
- 230000000737 periodic effect Effects 0.000 description 5
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 5
- FPCJKVGGYOAWIZ-UHFFFAOYSA-N butan-1-ol;titanium Chemical compound [Ti].CCCCO.CCCCO.CCCCO.CCCCO FPCJKVGGYOAWIZ-UHFFFAOYSA-N 0.000 description 4
- 229910052799 carbon Inorganic materials 0.000 description 4
- 239000002609 medium Substances 0.000 description 4
- 229910052751 metal Inorganic materials 0.000 description 4
- 239000002184 metal Substances 0.000 description 4
- DUNKXUFBGCUVQW-UHFFFAOYSA-J zirconium tetrachloride Chemical compound Cl[Zr](Cl)(Cl)Cl DUNKXUFBGCUVQW-UHFFFAOYSA-J 0.000 description 4
- INZDTEICWPZYJM-UHFFFAOYSA-N 1-(chloromethyl)-4-[4-(chloromethyl)phenyl]benzene Chemical compound C1=CC(CCl)=CC=C1C1=CC=C(CCl)C=C1 INZDTEICWPZYJM-UHFFFAOYSA-N 0.000 description 3
- 229910026551 ZrC Inorganic materials 0.000 description 3
- OTCHGXYCWNXDOA-UHFFFAOYSA-N [C].[Zr] Chemical compound [C].[Zr] OTCHGXYCWNXDOA-UHFFFAOYSA-N 0.000 description 3
- 238000001816 cooling Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 239000011521 glass Substances 0.000 description 3
- 239000007788 liquid Substances 0.000 description 3
- QSHDDOUJBYECFT-UHFFFAOYSA-N mercury Chemical compound [Hg] QSHDDOUJBYECFT-UHFFFAOYSA-N 0.000 description 3
- 229910052753 mercury Inorganic materials 0.000 description 3
- 229910052750 molybdenum Inorganic materials 0.000 description 3
- 239000011733 molybdenum Substances 0.000 description 3
- 238000010422 painting Methods 0.000 description 3
- 239000007787 solid Substances 0.000 description 3
- 239000000725 suspension Substances 0.000 description 3
- QIJNJJZPYXGIQM-UHFFFAOYSA-N 1lambda4,2lambda4-dimolybdacyclopropa-1,2,3-triene Chemical compound [Mo]=C=[Mo] QIJNJJZPYXGIQM-UHFFFAOYSA-N 0.000 description 2
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 2
- 229910039444 MoC Inorganic materials 0.000 description 2
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 2
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical group O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 2
- 239000012736 aqueous medium Substances 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 229910052804 chromium Inorganic materials 0.000 description 2
- 239000011651 chromium Substances 0.000 description 2
- 230000008602 contraction Effects 0.000 description 2
- 229910052802 copper Inorganic materials 0.000 description 2
- 239000010949 copper Substances 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 150000001247 metal acetylides Chemical class 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 2
- 229910052721 tungsten Inorganic materials 0.000 description 2
- 239000010937 tungsten Substances 0.000 description 2
- 229910011255 B2O3 Inorganic materials 0.000 description 1
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 1
- 229910021552 Vanadium(IV) chloride Inorganic materials 0.000 description 1
- 239000000853 adhesive Substances 0.000 description 1
- 230000001070 adhesive effect Effects 0.000 description 1
- 238000013019 agitation Methods 0.000 description 1
- 239000004411 aluminium Substances 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 238000000498 ball milling Methods 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 230000001680 brushing effect Effects 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- JKWMSGQKBLHBQQ-UHFFFAOYSA-N diboron trioxide Chemical compound O=BOB=O JKWMSGQKBLHBQQ-UHFFFAOYSA-N 0.000 description 1
- 239000000428 dust Substances 0.000 description 1
- 238000010410 dusting Methods 0.000 description 1
- 238000005485 electric heating Methods 0.000 description 1
- 150000002431 hydrogen Chemical class 0.000 description 1
- 229910000041 hydrogen chloride Inorganic materials 0.000 description 1
- IXCSERBJSXMMFS-UHFFFAOYSA-N hydrogen chloride Substances Cl.Cl IXCSERBJSXMMFS-UHFFFAOYSA-N 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 238000011065 in-situ storage Methods 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 229910052574 oxide ceramic Inorganic materials 0.000 description 1
- 239000011224 oxide ceramic Substances 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 238000007747 plating Methods 0.000 description 1
- 239000012254 powdered material Substances 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 239000004408 titanium dioxide Substances 0.000 description 1
- JTJFQBNJBPPZRI-UHFFFAOYSA-J vanadium tetrachloride Chemical group Cl[V](Cl)(Cl)Cl JTJFQBNJBPPZRI-UHFFFAOYSA-J 0.000 description 1
- 230000008016 vaporization Effects 0.000 description 1
- 238000009736 wetting Methods 0.000 description 1
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/515—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics
- C04B35/52—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics based on carbon, e.g. graphite
- C04B35/522—Graphite
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21J—FORGING; HAMMERING; PRESSING METAL; RIVETING; FORGE FURNACES
- B21J13/00—Details of machines for forging, pressing, or hammering
- B21J13/02—Dies or mountings therefor
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22C—FOUNDRY MOULDING
- B22C3/00—Selection of compositions for coating the surfaces of moulds, cores, or patterns
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/515—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics
- C04B35/58—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics based on borides, nitrides, i.e. nitrides, oxynitrides, carbonitrides or oxycarbonitrides or silicides
- C04B35/5805—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics based on borides, nitrides, i.e. nitrides, oxynitrides, carbonitrides or oxycarbonitrides or silicides based on borides
- C04B35/58064—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics based on borides, nitrides, i.e. nitrides, oxynitrides, carbonitrides or oxycarbonitrides or silicides based on borides based on refractory borides
- C04B35/58071—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics based on borides, nitrides, i.e. nitrides, oxynitrides, carbonitrides or oxycarbonitrides or silicides based on borides based on refractory borides based on titanium borides
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/622—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/64—Burning or sintering processes
- C04B35/645—Pressure sintering
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
- C04B41/45—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements
- C04B41/50—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements with inorganic materials
- C04B41/5053—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements with inorganic materials non-oxide ceramics
- C04B41/5057—Carbides
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/30—Self-sustaining carbon mass or layer with impregnant or other layer
Definitions
- This invention relates to improvements in dies and is particularly concerned with improvements in graphite dies for use in high temperature hot pressing processes which are performed at temperatures above 1000 C., e.g., up to about 2300 C., and in a method of producing same.
- Dies for use in high temperature hot pressing processes which are performed at temperatures above 1000 C. are commonly made of graphite in view of the resistance of this material to the high temperatures and pressures involved.
- the material to be hot pressed may be one which either reacts with or is mutually soluble in the material of the die at the pressing temperature and in these cases there is a tendency for the hot pressed body to stick to the die. Where such sticking occurs the least harmful result is that a new die has to be used for each pressing operation thereby adding considerably to the cost. It is quite possible, however, that sticking may cause the die to break before the pressing operation is completed, or it may result in the pressed body breaking during cooling as a result of the differential contraction of the die and the body.
- the surface or surfaces of the wall or walls defining the cavity in a graphite die for use in a high temperature hot pressing process is or are coated with a film of a carbide of one of the transition elements in Groups IV, V and VI of the Periodic System.
- the carbide is preferably titanium carbide.
- a method of manufacturing a graphite die for use in a high temperature hot pressing process comprises the step of coating the surface or surfaces of the wall or walls defining the die cavity with a film of a carbide of one of the transition elements in Groups IV, V and VI of the Perodic System.
- the carbide is preferably titanium carbide and it may be applied to the surface or surfaces in the form of a suspension of titanium carbide in butyl titanate paint medium and subsequently fired on to said surface or surfaces.
- the film of titanium carbide may be produced by heating the die, which is of graphite, and passing a mixture of vaporised titanium chloride and hydrogen over the surface or surfaces to form the film of titanium carbide thereon.
- the film of titanium carbide is fired on to the surface or surfaces e.g., by heating the die to a temperature of the order of 2,000 C. in an atmosphere of hydrogen.
- the carbide coating is applied to the graphite die surface in a moistened condition either by contacting the die cavity or bore surface or surfaces with an aqueous slurry of the carbide, or by sprinkling carbide dust onto the previously wetted die cavity surface.
- the carbide is applied in a moistened condition the coating is fired in situ; that is, the coating is fired onto the die surface during the hot pressing operation.
- the powder or material to be hot pressed is loaded into the die after coating the die cavity surface as above described, and the loaded die is then placed into a hot pressing assembly. As the assembly is brought up to the hot pressing temperature, the moisture is removed from the carbide coating, and the coating is fired onto the die cavity surface.
- FIGURE 1 illustrates diagrammatically one way of carrying the invention into effect
- FIGURE 2 is a view similar to FIGURE 1 illustrating a modification
- FIGURE 3 is a view similar to FIGURE 1 illustrating a further modification
- FIGURE 4 is a sectional view taken on the line IV- IV 'of FIGURE 5 of a cylindrical die according to the invention.
- FIGURE 5 is a section taken on the line VV of FIGURE 4.
- the surface or surfaces of the wall or walls defining the cavity of a graphite die may be coated with a film of a carbide of one of the transition elements in Groups IV, V and VI of the Periodic System by coating the surface or surfaces with a paint composed of the carbide of the transition element suspended in a suitable medium, the film so produced being allowed to dry and being fired on to the surface at an appropriate temperature in a protective atmosphere.
- a film of the carbide of one of the transition elements in Group IV or V may be produced by vaporizing or subliming, as the case may be, the tetrachloride of the transition element and passing it in admixture with hydrogen over the surface or surfaces of the die whilst the latter is heated to a temperature sufiicient to cause the graphite of the die to react with the tetrachloride of the transition element to produce the carbide of the latter with the formation of hydrogen chloride due to the hydrogen present in the gaseous mixture, the carbide being deposited as a film of substantially uniform thickness on the surface or surfaces and desirably being subsequently fired thereon at an appropriate temperature in a protective atmosphere.
- a film of the carbide of a transition element in Group VI may be produced on the surface or surfaces of the wall or walls defining the die cavity by exposing the surface or surfaces to a gaseous mixture of hydrogen and the carbonyl of the transition element at a reduced pressure of from 0.1 to 10 mm. of mercury and heating the die to a temperature sufiicient to cause the hydrogen to reduce the carbonyl to produce the carbide of the transition element which carbide is deposited as a film of substantially uniform thickness on the surface or surfaces, the carbide film being subsequently fired on to the surface or surfaces at a temperature between 2000 C.-2l00 C. in a protective atmosphere e.g., hydrogen.
- the firing may alternatively be effected after the powder to be pressed is loaded into the die and during the high temperature hot pressing operation.
- a paint composed of titanium carbide suspended in butyl titanate paint medium is prepared by ball-milling the titanium carbide in the butyl titanate for some hours, e.g., 8 hours.
- the surface or surfaces of the wall or walls defining the die cavity is or are then painted with the suspension and the film so produced is allowed to dry for one or more hours.
- the film is then fired on to the surface or surfaces by heating the die to a temperature of the order of 2000 C. in an atmosphere of hydrogen.
- Butyl titanate is preferred as the paint medium because its ultimate decomposition product is titanium dioxide which is reduced to give titanium carbide during the high temperature firing operation.
- An example of coating the surface or surfaces of the wall or walls of a graphite die with titanium carbide by this method is as follows: Liquid titanium tetrachloride 1 (FIGURE 1), contained in a suitable glass vessel 2, is heated to a temperature of 100 C.
- the glass vessel 2 is closed by a glass plug '7 through which extends a tube 8 opening into the space above the liquid titanium tetrachloride in the vessel 2 and communicating with the interior of a cylindrical graphite die 9.
- a branch tube 10 connects the tube 8 to the hydrogen source 4 and a tap 11 is connected in the tube 10.
- the hydrogen source 4 is connected to both the tubes 5 and 10 by a common tube 12 in which there is provided a further tap 13 whereby the hydrogen source may be isolated from the rest of the system.
- the die 9 is heated in any suitable manner, for example, by the electric heating coil 14 shown in FIGURE 1 which is connected by way of terminals 14a to a suitable source of supply.
- the water-bath 3 vaporizes the titanium tetrachloride and, with the taps 6 and 13 open and the tap 11 closed, a mixture of vaporized titanium chloride and hydrogen flows into the cavity or interior of the die 9 so that the surface of the wall thereof is exposed to this mixture.
- the die 9 is heated by the coil 14 to a temperature of from 1500 C.1600 C., e.g., 1550 C. and the mixture of vaporized titanium chloride and hydrogen is caused to flow through the die 9 for a period of one to two hours, e.g., one hour.
- the end of the die 9 remote from the tube 8 is restricted by a plug and the gases issue from this end as a jet which is ignited.
- the carbon of the die reacts with the titanium tetrachloride to form a film of titanium carbide on the internal wall of the die 9 and at the end of this period the tap 6 is closed and the tap 11 is opened so that the supply of vaporized titanium tetrachloride is discontinued and hydrogen only passes to the interior of the die 9, the latter now being heated by the coil 14 to a temperature of about 2050 C. for a short period of the order of 15 minutes and then being allowed to cool, the hydrogen atmosphere being mamtained during the cooling of the die.
- This high temperature heating improves the adherence of the titanium carbide to the die and removes any free titanium metal which might be present in the film by converting it to the carbide.
- the procedure described above may be used to coat the interior of the die 9 with vanadium carbide by substituting vanadium tetrachloride for the titanium tetrachloride in the vessel 2.
- the procedure described above is modified as shown in FIGURE 2 by substituting a copper tube 15 for the vessel 2 and water bath 3.
- a copper tube 15 for the vessel 2 and water bath 3.
- the zirconium tetrachloride is disposed in the copper tube 15 and is heated by any suitable means such as, for example,
- a tubular wire wound resistance furnace indicated very diagrammatically by the heating coil 16, to a temperature of from 250 C.300 C., e.g., 270 C. and hydrogen gas is passed through the tube 15 from the source 4 for a period of one to two hours as before and the mixture of hydrogen and zirconium tetrachloride passed into the die 9, which latter is in this case maintained at a temperature of between 1700 C. and 1900" C.
- the Zirconium tetrachloride reacts with the carbon of the die to form zirconium carbide as a film on the interior of the die 9 and at the end of the period the tap 6 is closed and the tap 11 is opened so that hydrogen is supplied to the interior of the die 9 whilst the latter is now heated by the coil 14 to a temperature of at least 2,100 C. for a short period of the order of 15 minutes after which it is allowed to cool whilst maintaining the atmosphere of hydrogen.
- the method of producing a film of the carbide of a transition element in Group VI using the carbonyl of the transition element is as follows:
- the die 9 (FIG. 3) is disposed in a vacuum furnace 17 the interior of which is connected by a pipe 18 through a tap 19 to a vacuum pump 20.
- the interior of the furnace 17 is also connected by a pipe 21 through a tap 22 to a container 23 containing the carbonyl of the transition element, e.g., molybdenum carbonyl (Mo(CO) which is a solid at normal temperature and pressure.
- the interior of the container 23 is connected by a pipe 24 and a tap 25 to a source 26 of hydrogen under pressure.
- the die 9 is heated to a temperature of about 500 C.
- the tap 19 is opened and the pump 20 operated to reduce the pressure in the furnace 17 to below 0.1 mm. of mercury.
- the taps 22 and 25 are opened to cause a gaseous mixture of hydrogen and the carbonyl to flow into the furnace 17, the taps 19 and 22 being adjusted to control the rate of flow of this gaseous mixture and the pressure within the furnace 1'7, this pressure being maintained at about 5 mm. of mercury and the rate of flow of the gaseous mixture being about /2 litre/min.
- the carbonyls of the transition elements in Group VI are solids at N.T.P. their vapor pressure is suflicient to provide the required quantity of gaseous carbonyl at the reduced pressure existing in the furnace 17.
- the gaseous mixture is allowed to flow into and through the furnace 17 for a period of at least 2 hours during which period the hydrogen reduces the carbonyl to the carbide which is deposited on the surface or surfaces of the die.
- the die 9 is cooled in a vacuum, and is subsequently removed from the furnace 17 and transferred to a high temperature furnace where it is heated to a temperature of 2000 C.2l00 C. in a protective atmosphere, e.g., hydrogen, for a period of about 15 minutes and allowed to cool whilst the protective atmosphere is maintained in order to tire the carbide film on to the surface or surfaces of the die.
- a protective atmosphere e.g., hydrogen
- a mixture of finely ground carbide powder and water is first prepared. Upon agitation the fine powder will be suspended within the aqueous medium.
- the coating is applied by temporarily sealing the lower end of the die in such a manner as to plug the cavity or bore.
- the aqueous slurry is then introduced into the die cavity and agitated.
- the slurry may be additionally agitated prior to introduction to the die cavity in order to ensure a suitable suspension of the carbide powder.
- the carbide particles will come out of the slurry and adhere to the surface or surfaces of the die cavity forming the desired film.
- Excess water and the temporary seal or plug are removed from the die cavity and the die is then loaded with the powder to be pressed.
- Protective gas such as argon, nitrogen, or hydrogen is introduced to the die cavity at the beginning of the pressing operation.
- the hot pressing die assembly is brought up to the temperature for hot pressing the moisture is removed, and the carbide film is subjected to a temperature of at least about 2000 C. to fire the coating onto the said surface or surfaces.
- the contacting of the surface or surfaces of the die cavity with the aqueous-carbide mixture or slurry may be accomplished by painting or brushing the slurry on to the said surface or surfaces.
- the desired carbide coating may be applied by first wetting the surface or surfaces of the die cavity with water in any convenient manner. Finely ground carbide powder is then dusted onto the wet surface. The so treated die is installed in the furnace, and the powder to be pressed is loaded into the die and subjected to the hot pressing operation.
- the aqueous medium in these methods acts as an adhesive enabling the carbide to remain on the die until the powder to be pressed is introduced into the die.
- the powder when in the die supports the carbide material on the die wall and prevents it from flaking off as would occur when the aqueous mixture is dried.
- the firing of the carbide coating can be accomplished either prior to the addition of the powder to the die or after the powder is introduced and during the hot pressing thereof.
- FIGURES 4 and 5 illustrate a cylindrical graphite die 9 having a coating 27 of carbide in accordance with this invention, the thickness of this coating being exaggerated for the purpose of illustration.
- FIGURE 4 also shows two plungers 28 which may be hydraulically operated for the purpose of exerting a pressure on any powdered material placed in the die 9 for hot pressing to the shape of a rod.
- a graphite die 9 having a carbide coating 27 in accordance with this invention is of particular, but not exclusive, application in the hot pressing of the diborides of titanium and zirconium.
- titanium diboride is hot pressed in a graphite die at a temperature of the order of 2000 C.
- the titanium diboride to stick to the die with the result that the latter breaks before the pressing operation is completed, or the pressed body of titanium diboride breaks during cooling as a result of the differential contraction of the die and the pressed body.
- These difliculties are not encountered when the hot pressing operation is performed at a temperature below 1700 C. but it is not possible to produce a satisfactory strong and dense body at such low temperatures.
- titanium diboride and carbon have some mutual solubility at temperatures of the order of 2000 C. or above or that the effect may be due to small amounts of impurity, such as boric oxide (B 0 which it is not economic to remove from the titanium diboride powder.
- impurity such as boric oxide (B 0 which it is not economic to remove from the titanium diboride powder.
- B 0 boric oxide
- titanium diboride may be satisfactorily hot pressed at temperatures of the order of 2000 C. and above in a graphite die when the surface or surfaces of the wall or walls defining the cavity in the die is or are coated with a film of the carbide of one of the transition elements in Groups IV, V and VI of the Periodic System, e.g., titanium carbide.
- Reasonable hot pressed bodies of titanium diboride may be produced in graphite dies treated by the first method described above, i.e., by painting and firing, but it is extremely desirable, if not essential, that the painting and firing be repeated after each pressing operation.
- Titanium diboride can be hot pressed at the highest temperatures normally used (about 2050 C.) in a die treated by any of the other methods described above without sticking occurring and a number of pressings (at least six) can be obtained from a given die without further treatment.
- a powder of titanium diboride was hot-pressed in a cylindrical graphite die 9 such as illustrated in FIGURE 4 at a maximum temperature of 2050 C. and a maximum pressure of 1 ton/sq. in. on the plungers 28.
- the surface of the die 9 defining the cavity was coated with titanium carbide by the tetrachloride method described above.
- the resultant titanium diboride bar had a low porosity of the order of 6% by volume and a transverse rupture modulus of about 15 tons per sq. in. No sticking of the titanium diboride to the die 9 occurred and the surface of the die 9 defining the cavity was unimpaired and the die 9 was suitable for further operations.
- a film of titanium carbide on the surface or surfaces of the wall or walls defining the die cavity is beneficial not only in the hot pressing of titanium diboride and the borides or diborides of the other transition elements in Groups IV, V and VI of the Periodic System but is also beneficial for the hot pressing of the carbides of such elements.
- the soft graphite dies do score in use and often have to be discarded for this reason alone.
- the treated dies show no signs of scoring since the film is both hard and durable. This film is also helpful in minimizing die reaction in cases where the material being hot pressed reacts with the material of the die.
- oxide ceramics tend to react with the graphite of the die during pressing, but oxides are in general much less reactive towards titanium carbide.
- titanium carbide, vanadium carbide, zirconium carbide or molybdenum carbide on the surface or surfaces of the wall or walls of the die cavity it is not limited to the film being of one of these carbides as it is within the scope of the invention to provide such a film of a carbide of any one of the transition elements of Groups 1V, V and VI of the Periodic System, namely, titanium, zirconium and hafnium, vanadium, niobium and tantalum and chromium, molybdenum and tungsten.
- titanium tetrachloride is both the cheapest and most freely available material for producing a suitable film on the surface or surfaces of the wall or Walls of the die cavity so that it is most economic to form the film from titanium carbide.
- a graphite die for use in a high temperature hot pressing process having disposed on the surfaces defining a die cavity a fired coating comprising a film of a carbide of a metal selected from the group consisting of titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum and tungsten, said film containing no free metal.
- a graphite die as in claim 1 wherein the fired coating is titanium carbide.
- a graphite die as in claim 1 wherein the fired coating is zirconium carbide.
- a graphite die as in claim 1 wherein the fired coating is molybdenum carbide.
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Ceramic Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Structural Engineering (AREA)
- Organic Chemistry (AREA)
- Mechanical Engineering (AREA)
- Inorganic Chemistry (AREA)
- Press-Shaping Or Shaping Using Conveyers (AREA)
- Carbon And Carbon Compounds (AREA)
Description
Apnl 6, 1965 E. H. AMSTEIN 3,177,084
METHOD OF MAKING CARBIDE-COATED GRAPHITE DIES AND COATED ARTICLE Filed April 20. 1961 INVENTOR EDMUND HOLLIS AMSTEIN ATTORNEY United States Patent 3,177,084 METHOD OF MAKING CIDE-COATED GRAPH- ITE DIES AND COATED ARTICLE Edmund Hollis Amstein, Chester, England, assignor to The British Aluminium Company Limited, London, England, a company of Great Britain Filed Apr. 20, 11961, Ser. No. 104,466 Claims priority, application Great Britain, Aug. 23, 1956, 25,822/ 56 5 Claims. (Cl. 1175.1)
This invention relates to improvements in dies and is particularly concerned with improvements in graphite dies for use in high temperature hot pressing processes which are performed at temperatures above 1000 C., e.g., up to about 2300 C., and in a method of producing same.
This application is a continuation-in-part of copending application, S.N. 679,387, entitled Method of Making Carbide Coated Graphite Dies and Coated Article, filed August 21, 1957, now abandoned.
Dies for use in high temperature hot pressing processes which are performed at temperatures above 1000 C. are commonly made of graphite in view of the resistance of this material to the high temperatures and pressures involved. In some cases, however, the material to be hot pressed may be one which either reacts with or is mutually soluble in the material of the die at the pressing temperature and in these cases there is a tendency for the hot pressed body to stick to the die. Where such sticking occurs the least harmful result is that a new die has to be used for each pressing operation thereby adding considerably to the cost. It is quite possible, however, that sticking may cause the die to break before the pressing operation is completed, or it may result in the pressed body breaking during cooling as a result of the differential contraction of the die and the body.
It is an object of the present invention to provide an improved die for use in high temperature hot pressing processes which shall not be subject to the disadvantages referred to.
According to one feature of the present invention the surface or surfaces of the wall or walls defining the cavity in a graphite die for use in a high temperature hot pressing process is or are coated with a film of a carbide of one of the transition elements in Groups IV, V and VI of the Periodic System.
The carbide is preferably titanium carbide.
According to another feature of the present invention, a method of manufacturing a graphite die for use in a high temperature hot pressing process comprises the step of coating the surface or surfaces of the wall or walls defining the die cavity with a film of a carbide of one of the transition elements in Groups IV, V and VI of the Perodic System.
The carbide is preferably titanium carbide and it may be applied to the surface or surfaces in the form of a suspension of titanium carbide in butyl titanate paint medium and subsequently fired on to said surface or surfaces. Alternatively the film of titanium carbide may be produced by heating the die, which is of graphite, and passing a mixture of vaporised titanium chloride and hydrogen over the surface or surfaces to form the film of titanium carbide thereon. Preferably the film of titanium carbide is fired on to the surface or surfaces e.g., by heating the die to a temperature of the order of 2,000 C. in an atmosphere of hydrogen.
In another embodiment of the invention, the carbide coating is applied to the graphite die surface in a moistened condition either by contacting the die cavity or bore surface or surfaces with an aqueous slurry of the carbide, or by sprinkling carbide dust onto the previously wetted die cavity surface. When the carbide is applied in a moistened condition the coating is fired in situ; that is, the coating is fired onto the die surface during the hot pressing operation. The powder or material to be hot pressed is loaded into the die after coating the die cavity surface as above described, and the loaded die is then placed into a hot pressing assembly. As the assembly is brought up to the hot pressing temperature, the moisture is removed from the carbide coating, and the coating is fired onto the die cavity surface. I
The invention will now be described by way of example, reference being made to the accompanying drawings in which:
FIGURE 1 illustrates diagrammatically one way of carrying the invention into effect,
FIGURE 2 is a view similar to FIGURE 1 illustrating a modification,
FIGURE 3 is a view similar to FIGURE 1 illustrating a further modification,
FIGURE 4 is a sectional view taken on the line IV- IV 'of FIGURE 5 of a cylindrical die according to the invention, and
FIGURE 5 is a section taken on the line VV of FIGURE 4.
The surface or surfaces of the wall or walls defining the cavity of a graphite die may be coated with a film of a carbide of one of the transition elements in Groups IV, V and VI of the Periodic System by coating the surface or surfaces with a paint composed of the carbide of the transition element suspended in a suitable medium, the film so produced being allowed to dry and being fired on to the surface at an appropriate temperature in a protective atmosphere. Alternatively a film of the carbide of one of the transition elements in Group IV or V may be produced by vaporizing or subliming, as the case may be, the tetrachloride of the transition element and passing it in admixture with hydrogen over the surface or surfaces of the die whilst the latter is heated to a temperature sufiicient to cause the graphite of the die to react with the tetrachloride of the transition element to produce the carbide of the latter with the formation of hydrogen chloride due to the hydrogen present in the gaseous mixture, the carbide being deposited as a film of substantially uniform thickness on the surface or surfaces and desirably being subsequently fired thereon at an appropriate temperature in a protective atmosphere. A film of the carbide of a transition element in Group VI may be produced on the surface or surfaces of the wall or walls defining the die cavity by exposing the surface or surfaces to a gaseous mixture of hydrogen and the carbonyl of the transition element at a reduced pressure of from 0.1 to 10 mm. of mercury and heating the die to a temperature sufiicient to cause the hydrogen to reduce the carbonyl to produce the carbide of the transition element which carbide is deposited as a film of substantially uniform thickness on the surface or surfaces, the carbide film being subsequently fired on to the surface or surfaces at a temperature between 2000 C.-2l00 C. in a protective atmosphere e.g., hydrogen. When the carbide coating is applied by contacting the die surface with an aqueous slurry of the carbide or by dusting onto a previously wetted die surface, the firing may alternatively be effected after the powder to be pressed is loaded into the die and during the high temperature hot pressing operation.
An example of the first of these methods is as follows: a paint composed of titanium carbide suspended in butyl titanate paint medium is prepared by ball-milling the titanium carbide in the butyl titanate for some hours, e.g., 8 hours. The surface or surfaces of the wall or walls defining the die cavity is or are then painted with the suspension and the film so produced is allowed to dry for one or more hours. The film is then fired on to the surface or surfaces by heating the die to a temperature of the order of 2000 C. in an atmosphere of hydrogen. Butyl titanate is preferred as the paint medium because its ultimate decomposition product is titanium dioxide which is reduced to give titanium carbide during the high temperature firing operation.
The method of producing a film of the carbide of a transition element in Group IV or V using the tetrachloride of the transition element is based on the reaction MCl +C+2H =MC+4HCl (where M is the transition element) which can, under suitable conditions, produce a film of the carbide of the transition element on carbon. An example of coating the surface or surfaces of the wall or walls of a graphite die with titanium carbide by this method is as follows: Liquid titanium tetrachloride 1 (FIGURE 1), contained in a suitable glass vessel 2, is heated to a temperature of 100 C. in a water bath 3 and hydrogen is passed through it at about 4 litres per minute from a source 4 of hydrogen under pressure by way of a tube 5 one end of which is immersed in the liquid titanium tetrachloride. A tap 6 is connected in the tube 5. The glass vessel 2 is closed by a glass plug '7 through which extends a tube 8 opening into the space above the liquid titanium tetrachloride in the vessel 2 and communicating with the interior of a cylindrical graphite die 9. A branch tube 10 connects the tube 8 to the hydrogen source 4 and a tap 11 is connected in the tube 10. The hydrogen source 4 is connected to both the tubes 5 and 10 by a common tube 12 in which there is provided a further tap 13 whereby the hydrogen source may be isolated from the rest of the system. The die 9 is heated in any suitable manner, for example, by the electric heating coil 14 shown in FIGURE 1 which is connected by way of terminals 14a to a suitable source of supply.
The water-bath 3 vaporizes the titanium tetrachloride and, with the taps 6 and 13 open and the tap 11 closed, a mixture of vaporized titanium chloride and hydrogen flows into the cavity or interior of the die 9 so that the surface of the wall thereof is exposed to this mixture. The die 9 is heated by the coil 14 to a temperature of from 1500 C.1600 C., e.g., 1550 C. and the mixture of vaporized titanium chloride and hydrogen is caused to flow through the die 9 for a period of one to two hours, e.g., one hour. The end of the die 9 remote from the tube 8 is restricted by a plug and the gases issue from this end as a jet which is ignited. During the period referred to the carbon of the die reacts with the titanium tetrachloride to form a film of titanium carbide on the internal wall of the die 9 and at the end of this period the tap 6 is closed and the tap 11 is opened so that the supply of vaporized titanium tetrachloride is discontinued and hydrogen only passes to the interior of the die 9, the latter now being heated by the coil 14 to a temperature of about 2050 C. for a short period of the order of 15 minutes and then being allowed to cool, the hydrogen atmosphere being mamtained during the cooling of the die. This high temperature heating improves the adherence of the titanium carbide to the die and removes any free titanium metal which might be present in the film by converting it to the carbide.
The procedure described above may be used to coat the interior of the die 9 with vanadium carbide by substituting vanadium tetrachloride for the titanium tetrachloride in the vessel 2.
Where the tetrachloride of the transition element is a solid which sublimes such as in the case of zirconium tetrachloride the procedure described above is modified as shown in FIGURE 2 by substituting a copper tube 15 for the vessel 2 and water bath 3. Like reference numerals are used to indicate like parts in FIGURES 1 and 2. The zirconium tetrachloride is disposed in the copper tube 15 and is heated by any suitable means such as, for example,
a tubular wire wound resistance furnace indicated very diagrammatically by the heating coil 16, to a temperature of from 250 C.300 C., e.g., 270 C. and hydrogen gas is passed through the tube 15 from the source 4 for a period of one to two hours as before and the mixture of hydrogen and zirconium tetrachloride passed into the die 9, which latter is in this case maintained at a temperature of between 1700 C. and 1900" C. During this period the Zirconium tetrachloride reacts with the carbon of the die to form zirconium carbide as a film on the interior of the die 9 and at the end of the period the tap 6 is closed and the tap 11 is opened so that hydrogen is supplied to the interior of the die 9 whilst the latter is now heated by the coil 14 to a temperature of at least 2,100 C. for a short period of the order of 15 minutes after which it is allowed to cool whilst maintaining the atmosphere of hydrogen.
The method of producing a film of the carbide of a transition element in Group VI using the carbonyl of the transition element is as follows: The die 9 (FIG. 3) is disposed in a vacuum furnace 17 the interior of which is connected by a pipe 18 through a tap 19 to a vacuum pump 20. The interior of the furnace 17 is also connected by a pipe 21 through a tap 22 to a container 23 containing the carbonyl of the transition element, e.g., molybdenum carbonyl (Mo(CO) which is a solid at normal temperature and pressure. The interior of the container 23 is connected by a pipe 24 and a tap 25 to a source 26 of hydrogen under pressure. The die 9 is heated to a temperature of about 500 C. and the tap 19 is opened and the pump 20 operated to reduce the pressure in the furnace 17 to below 0.1 mm. of mercury. The taps 22 and 25 are opened to cause a gaseous mixture of hydrogen and the carbonyl to flow into the furnace 17, the taps 19 and 22 being adjusted to control the rate of flow of this gaseous mixture and the pressure within the furnace 1'7, this pressure being maintained at about 5 mm. of mercury and the rate of flow of the gaseous mixture being about /2 litre/min. It will be understood that although the carbonyls of the transition elements in Group VI are solids at N.T.P. their vapor pressure is suflicient to provide the required quantity of gaseous carbonyl at the reduced pressure existing in the furnace 17. The gaseous mixture is allowed to flow into and through the furnace 17 for a period of at least 2 hours during which period the hydrogen reduces the carbonyl to the carbide which is deposited on the surface or surfaces of the die. After this the die 9 is cooled in a vacuum, and is subsequently removed from the furnace 17 and transferred to a high temperature furnace where it is heated to a temperature of 2000 C.2l00 C. in a protective atmosphere, e.g., hydrogen, for a period of about 15 minutes and allowed to cool whilst the protective atmosphere is maintained in order to tire the carbide film on to the surface or surfaces of the die.
In the method of applying the carbide coating to the die cavity surface or surfaces by contacting the said surface or surfaces with a slurry of the metal carbide, a mixture of finely ground carbide powder and water is first prepared. Upon agitation the fine powder will be suspended within the aqueous medium. The coating is applied by temporarily sealing the lower end of the die in such a manner as to plug the cavity or bore. The aqueous slurry is then introduced into the die cavity and agitated. The slurry may be additionally agitated prior to introduction to the die cavity in order to ensure a suitable suspension of the carbide powder. The carbide particles will come out of the slurry and adhere to the surface or surfaces of the die cavity forming the desired film. Excess water and the temporary seal or plug are removed from the die cavity and the die is then loaded with the powder to be pressed. Protective gas such as argon, nitrogen, or hydrogen is introduced to the die cavity at the beginning of the pressing operation. As the hot pressing die assembly is brought up to the temperature for hot pressing the moisture is removed, and the carbide film is subjected to a temperature of at least about 2000 C. to fire the coating onto the said surface or surfaces.
Alternatively, the contacting of the surface or surfaces of the die cavity with the aqueous-carbide mixture or slurry may be accomplished by painting or brushing the slurry on to the said surface or surfaces. Also, the desired carbide coating may be applied by first wetting the surface or surfaces of the die cavity with water in any convenient manner. Finely ground carbide powder is then dusted onto the wet surface. The so treated die is installed in the furnace, and the powder to be pressed is loaded into the die and subjected to the hot pressing operation.
The aqueous medium in these methods acts as an adhesive enabling the carbide to remain on the die until the powder to be pressed is introduced into the die. The powder when in the die suports the carbide material on the die wall and prevents it from flaking off as would occur when the aqueous mixture is dried. Thus, it is ap parent that the firing of the carbide coating can be accomplished either prior to the addition of the powder to the die or after the powder is introduced and during the hot pressing thereof.
FIGURES 4 and 5 illustrate a cylindrical graphite die 9 having a coating 27 of carbide in accordance with this invention, the thickness of this coating being exaggerated for the purpose of illustration. FIGURE 4 also shows two plungers 28 which may be hydraulically operated for the purpose of exerting a pressure on any powdered material placed in the die 9 for hot pressing to the shape of a rod.
A graphite die 9 having a carbide coating 27 in accordance with this invention is of particular, but not exclusive, application in the hot pressing of the diborides of titanium and zirconium. For example, when titanium diboride is hot pressed in a graphite die at a temperature of the order of 2000 C. there is a marked tendency for the titanium diboride to stick to the die with the result that the latter breaks before the pressing operation is completed, or the pressed body of titanium diboride breaks during cooling as a result of the differential contraction of the die and the pressed body. These difliculties are not encountered when the hot pressing operation is performed at a temperature below 1700 C. but it is not possible to produce a satisfactory strong and dense body at such low temperatures. It is thought that titanium diboride and carbon have some mutual solubility at temperatures of the order of 2000 C. or above or that the effect may be due to small amounts of impurity, such as boric oxide (B 0 which it is not economic to remove from the titanium diboride powder. Whatever the reason for the sticking effect we have found that titanium diboride may be satisfactorily hot pressed at temperatures of the order of 2000 C. and above in a graphite die when the surface or surfaces of the wall or walls defining the cavity in the die is or are coated with a film of the carbide of one of the transition elements in Groups IV, V and VI of the Periodic System, e.g., titanium carbide.
Reasonable hot pressed bodies of titanium diboride may be produced in graphite dies treated by the first method described above, i.e., by painting and firing, but it is extremely desirable, if not essential, that the painting and firing be repeated after each pressing operation.
Titanium diboride can be hot pressed at the highest temperatures normally used (about 2050 C.) in a die treated by any of the other methods described above without sticking occurring and a number of pressings (at least six) can be obtained from a given die without further treatment. As an example a powder of titanium diboride was hot-pressed in a cylindrical graphite die 9 such as illustrated in FIGURE 4 at a maximum temperature of 2050 C. and a maximum pressure of 1 ton/sq. in. on the plungers 28. The surface of the die 9 defining the cavity was coated with titanium carbide by the tetrachloride method described above. The resultant titanium diboride bar had a low porosity of the order of 6% by volume and a transverse rupture modulus of about 15 tons per sq. in. No sticking of the titanium diboride to the die 9 occurred and the surface of the die 9 defining the cavity was unimpaired and the die 9 was suitable for further operations.
The provision of a film of titanium carbide on the surface or surfaces of the wall or walls defining the die cavity is beneficial not only in the hot pressing of titanium diboride and the borides or diborides of the other transition elements in Groups IV, V and VI of the Periodic System but is also beneficial for the hot pressing of the carbides of such elements. For example, although sticking does not occur appreciably in the hot pressing of titanium carbide, the soft graphite dies do score in use and often have to be discarded for this reason alone. The treated dies, however, show no signs of scoring since the film is both hard and durable. This film is also helpful in minimizing die reaction in cases where the material being hot pressed reacts with the material of the die.
For example, oxide ceramics tend to react with the graphite of the die during pressing, but oxides are in general much less reactive towards titanium carbide.
It will be appreciated that although the invention has been specifically described with reference to producing a film of titanium carbide, vanadium carbide, zirconium carbide or molybdenum carbide on the surface or surfaces of the wall or walls of the die cavity it is not limited to the film being of one of these carbides as it is within the scope of the invention to provide such a film of a carbide of any one of the transition elements of Groups 1V, V and VI of the Periodic System, namely, titanium, zirconium and hafnium, vanadium, niobium and tantalum and chromium, molybdenum and tungsten. At present, however, titanium tetrachloride is both the cheapest and most freely available material for producing a suitable film on the surface or surfaces of the wall or Walls of the die cavity so that it is most economic to form the film from titanium carbide.
What I claim is:
1. A graphite die for use in a high temperature hot pressing process having disposed on the surfaces defining a die cavity a fired coating comprising a film of a carbide of a metal selected from the group consisting of titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum and tungsten, said film containing no free metal.
2. A graphite die as in claim 1 wherein the fired coating is titanium carbide.
3. A graphite die as in claim 1 wherein the fired coating is zirconium carbide.
4. A graphite die as in claim 1 wherein the fired coating is molybdenum carbide.
5. A graphite die as in claim 1 wherein the fire coating is vanadium carbide.
References Cited by the Examiner UNITED STATES PATENTS 2,860,075 11/58 Alexander et a1. 117-228 X OTHER REFERENCES Powell: Vapor Plating (1955), Wiley, New York, pages 73-79 relied on.
RICHARD D. NEVIUS, Primary Examiner.
Claims (1)
1. A GRAPHITE DIE FOR USE IN A HIGH TEMPERATURE HOT PRESSING PROCESS HAVING DISPOSED ON THE SURFACES DEFINING A DIE CAVITY A FIRED COATING COMPRISING A FILM OF A CARBIDE OF A METAL SELECTED FROM THE GROUP CONSISTING OF TITANIUM, ZIRCONIUM, HAFNIUM, VANADIUM, NIOBIUM, TANTALUM, CHRO-
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB25822/56A GB877408A (en) | 1956-08-23 | 1956-08-23 | Improvements in or relating to dies |
Publications (1)
Publication Number | Publication Date |
---|---|
US3177084A true US3177084A (en) | 1965-04-06 |
Family
ID=10233887
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US104466A Expired - Lifetime US3177084A (en) | 1956-08-23 | 1961-04-20 | Method of making carbide-coated graphite dies and coated article |
Country Status (3)
Country | Link |
---|---|
US (1) | US3177084A (en) |
CH (1) | CH366128A (en) |
GB (1) | GB877408A (en) |
Cited By (15)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3264135A (en) * | 1962-11-28 | 1966-08-02 | Noel T Wakelyn | Method of coating carbonaceous base to prevent oxidation destruction and coated base |
US3271181A (en) * | 1963-05-29 | 1966-09-06 | Robert A Jewell | Method of coating carbonaceous base to prevent oxidation destruction and coated base |
US3389743A (en) * | 1965-07-12 | 1968-06-25 | Morozov Evgeny Ilich | Method of making resinous shell molds |
US3416944A (en) * | 1964-10-26 | 1968-12-17 | Air Force Usa | Ablative product and method for its manufactur |
US3498359A (en) * | 1966-03-09 | 1970-03-03 | Imp Metal Ind Kynoch Ltd | Moulds for use in metal casting |
US3642522A (en) * | 1969-07-15 | 1972-02-15 | Suisse Horlogerie Rech Lab | Method for producing hard coatings on a surface |
US4095449A (en) * | 1975-06-09 | 1978-06-20 | The Valeron Corporation | Coated punch |
US4135030A (en) * | 1977-12-23 | 1979-01-16 | United Technologies Corporation | Tungsten impregnated casting mold |
US20090224443A1 (en) * | 2008-03-05 | 2009-09-10 | Rundquist Victor F | Niobium as a protective barrier in molten metals |
US20110052180A1 (en) * | 2009-08-31 | 2011-03-03 | Hon Hai Precision Industry Co., Ltd. | Light blocking plate, camera module having same, and method for making same |
US8574336B2 (en) | 2010-04-09 | 2013-11-05 | Southwire Company | Ultrasonic degassing of molten metals |
US8652397B2 (en) | 2010-04-09 | 2014-02-18 | Southwire Company | Ultrasonic device with integrated gas delivery system |
US9528167B2 (en) | 2013-11-18 | 2016-12-27 | Southwire Company, Llc | Ultrasonic probes with gas outlets for degassing of molten metals |
US10233515B1 (en) | 2015-08-14 | 2019-03-19 | Southwire Company, Llc | Metal treatment station for use with ultrasonic degassing system |
US11107675B2 (en) | 2016-07-14 | 2021-08-31 | Entegris, Inc. | CVD Mo deposition by using MoOCl4 |
Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2860075A (en) * | 1951-01-27 | 1958-11-11 | Continental Can Co | Method of making a heater for vacuum deposition |
-
1956
- 1956-08-23 GB GB25822/56A patent/GB877408A/en not_active Expired
-
1957
- 1957-08-22 CH CH4971757A patent/CH366128A/en unknown
-
1961
- 1961-04-20 US US104466A patent/US3177084A/en not_active Expired - Lifetime
Patent Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2860075A (en) * | 1951-01-27 | 1958-11-11 | Continental Can Co | Method of making a heater for vacuum deposition |
Cited By (25)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3264135A (en) * | 1962-11-28 | 1966-08-02 | Noel T Wakelyn | Method of coating carbonaceous base to prevent oxidation destruction and coated base |
US3271181A (en) * | 1963-05-29 | 1966-09-06 | Robert A Jewell | Method of coating carbonaceous base to prevent oxidation destruction and coated base |
US3416944A (en) * | 1964-10-26 | 1968-12-17 | Air Force Usa | Ablative product and method for its manufactur |
US3389743A (en) * | 1965-07-12 | 1968-06-25 | Morozov Evgeny Ilich | Method of making resinous shell molds |
US3498359A (en) * | 1966-03-09 | 1970-03-03 | Imp Metal Ind Kynoch Ltd | Moulds for use in metal casting |
US3642522A (en) * | 1969-07-15 | 1972-02-15 | Suisse Horlogerie Rech Lab | Method for producing hard coatings on a surface |
US4095449A (en) * | 1975-06-09 | 1978-06-20 | The Valeron Corporation | Coated punch |
US4135030A (en) * | 1977-12-23 | 1979-01-16 | United Technologies Corporation | Tungsten impregnated casting mold |
CN103056318A (en) * | 2008-03-05 | 2013-04-24 | 南线公司 | Niobium as a protective barrier in molten metals |
US9327347B2 (en) | 2008-03-05 | 2016-05-03 | Southwire Company, Llc | Niobium as a protective barrier in molten metals |
EP2452763A1 (en) * | 2008-03-05 | 2012-05-16 | Southwire Company | Graphite die with protective niobium layer and associated die-casting method |
US20090224443A1 (en) * | 2008-03-05 | 2009-09-10 | Rundquist Victor F | Niobium as a protective barrier in molten metals |
CN103056318B (en) * | 2008-03-05 | 2017-06-09 | 南线有限责任公司 | As the niobium of the protective wall in motlten metal |
US8844897B2 (en) * | 2008-03-05 | 2014-09-30 | Southwire Company, Llc | Niobium as a protective barrier in molten metals |
US8009980B2 (en) * | 2009-08-31 | 2011-08-30 | Hon Hai Precision Industry Co., Ltd. | Light blocking plate, camera module having same, and method for making same |
US20110052180A1 (en) * | 2009-08-31 | 2011-03-03 | Hon Hai Precision Industry Co., Ltd. | Light blocking plate, camera module having same, and method for making same |
US9382598B2 (en) | 2010-04-09 | 2016-07-05 | Southwire Company, Llc | Ultrasonic device with integrated gas delivery system |
US8652397B2 (en) | 2010-04-09 | 2014-02-18 | Southwire Company | Ultrasonic device with integrated gas delivery system |
US9617617B2 (en) | 2010-04-09 | 2017-04-11 | Southwire Company, Llc | Ultrasonic degassing of molten metals |
US8574336B2 (en) | 2010-04-09 | 2013-11-05 | Southwire Company | Ultrasonic degassing of molten metals |
US10640846B2 (en) | 2010-04-09 | 2020-05-05 | Southwire Company, Llc | Ultrasonic degassing of molten metals |
US9528167B2 (en) | 2013-11-18 | 2016-12-27 | Southwire Company, Llc | Ultrasonic probes with gas outlets for degassing of molten metals |
US10316387B2 (en) | 2013-11-18 | 2019-06-11 | Southwire Company, Llc | Ultrasonic probes with gas outlets for degassing of molten metals |
US10233515B1 (en) | 2015-08-14 | 2019-03-19 | Southwire Company, Llc | Metal treatment station for use with ultrasonic degassing system |
US11107675B2 (en) | 2016-07-14 | 2021-08-31 | Entegris, Inc. | CVD Mo deposition by using MoOCl4 |
Also Published As
Publication number | Publication date |
---|---|
CH366128A (en) | 1962-12-15 |
GB877408A (en) | 1961-09-13 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US3177084A (en) | Method of making carbide-coated graphite dies and coated article | |
US2351798A (en) | Coating metal articles | |
US4217948A (en) | Method for production of two-layer pipe casting | |
DE2357814A1 (en) | GRAPHITE BODY WITH SILICON CARBIDE COATING | |
US3050409A (en) | Manufacture of refractory oxide coatings | |
DE3206622C2 (en) | ||
US4299881A (en) | Graphitic molded article with corrosion-resistant surface layer stable under stress | |
US2867546A (en) | Gas plating of aluminum using aluminum trilsobutyl | |
US2604395A (en) | Method of producing metallic bodies | |
US3139658A (en) | Production of tungsten objects | |
US3446607A (en) | Iridium coated graphite | |
US4135030A (en) | Tungsten impregnated casting mold | |
US2904456A (en) | Metalizing ceramics | |
Miyake et al. | Chemical vapor deposition of niobium on graphite | |
US2831784A (en) | Gastinger | |
US1019394A (en) | Reduction of chemical compounds. | |
US3589927A (en) | Chromising of ferrous metal substrates | |
US2886469A (en) | Method of coating metallic bodies with aluminum utilizing vaporous sub-chlorides | |
US3050417A (en) | Chromium nickel alloy gas plating | |
US3433682A (en) | Silicon coated graphite | |
DE2635167C2 (en) | Process for reducing the gas permeability of porous bodies made of reaction-sintered silicon nitride | |
US2839426A (en) | Method of coating carbonaceous articles with silicon nitride | |
US2950979A (en) | Carbon structure and spray nozzle formed therefrom | |
DE1621280C2 (en) | Gas plating process for the production of hard coatings | |
US3208872A (en) | Carbide coatings on graphite |