US3833402A - Graphite fiber treatment - Google Patents
Graphite fiber treatment Download PDFInfo
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- US3833402A US3833402A US00238262A US23826272A US3833402A US 3833402 A US3833402 A US 3833402A US 00238262 A US00238262 A US 00238262A US 23826272 A US23826272 A US 23826272A US 3833402 A US3833402 A US 3833402A
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- fiber
- graphite
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- 239000000835 fiber Substances 0.000 title claims abstract description 109
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 title claims abstract description 60
- 229910002804 graphite Inorganic materials 0.000 title claims abstract description 53
- 239000010439 graphite Substances 0.000 title claims abstract description 53
- 238000011282 treatment Methods 0.000 title description 8
- 239000002131 composite material Substances 0.000 claims abstract description 23
- 238000000034 method Methods 0.000 claims description 26
- 238000000354 decomposition reaction Methods 0.000 claims description 14
- 239000002904 solvent Substances 0.000 claims description 13
- 150000002902 organometallic compounds Chemical class 0.000 claims description 12
- 239000000203 mixture Substances 0.000 claims description 10
- 230000008569 process Effects 0.000 claims description 9
- 230000006872 improvement Effects 0.000 claims description 8
- XEHUIDSUOAGHBW-UHFFFAOYSA-N chromium;pentane-2,4-dione Chemical compound [Cr].CC(=O)CC(C)=O.CC(=O)CC(C)=O.CC(=O)CC(C)=O XEHUIDSUOAGHBW-UHFFFAOYSA-N 0.000 claims description 5
- ILZSSCVGGYJLOG-UHFFFAOYSA-N cobaltocene Chemical compound [Co+2].C=1C=C[CH-]C=1.C=1C=C[CH-]C=1 ILZSSCVGGYJLOG-UHFFFAOYSA-N 0.000 claims description 5
- 229960002413 ferric citrate Drugs 0.000 claims description 5
- VEPSWGHMGZQCIN-UHFFFAOYSA-H ferric oxalate Chemical compound [Fe+3].[Fe+3].[O-]C(=O)C([O-])=O.[O-]C(=O)C([O-])=O.[O-]C(=O)C([O-])=O VEPSWGHMGZQCIN-UHFFFAOYSA-H 0.000 claims description 5
- NPFOYSMITVOQOS-UHFFFAOYSA-K iron(III) citrate Chemical compound [Fe+3].[O-]C(=O)CC(O)(CC([O-])=O)C([O-])=O NPFOYSMITVOQOS-UHFFFAOYSA-K 0.000 claims description 5
- 229910052751 metal Inorganic materials 0.000 abstract description 27
- 239000002184 metal Substances 0.000 abstract description 27
- 150000001875 compounds Chemical class 0.000 abstract description 24
- 238000000151 deposition Methods 0.000 abstract description 2
- 239000003733 fiber-reinforced composite Substances 0.000 abstract 1
- 238000010438 heat treatment Methods 0.000 description 11
- 229920000049 Carbon (fiber) Polymers 0.000 description 9
- 239000004917 carbon fiber Substances 0.000 description 9
- 229910052799 carbon Inorganic materials 0.000 description 7
- 239000011651 chromium Substances 0.000 description 4
- 229910052804 chromium Inorganic materials 0.000 description 4
- 238000001035 drying Methods 0.000 description 4
- 239000007789 gas Substances 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 239000011347 resin Substances 0.000 description 4
- 229920005989 resin Polymers 0.000 description 4
- UHOVQNZJYSORNB-UHFFFAOYSA-N Benzene Chemical compound C1=CC=CC=C1 UHOVQNZJYSORNB-UHFFFAOYSA-N 0.000 description 3
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 3
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 description 3
- 239000003795 chemical substances by application Substances 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 239000011261 inert gas Substances 0.000 description 3
- 230000003647 oxidation Effects 0.000 description 3
- 238000007254 oxidation reaction Methods 0.000 description 3
- 238000013459 approach Methods 0.000 description 2
- KTWOOEGAPBSYNW-UHFFFAOYSA-N ferrocene Chemical compound [Fe+2].C=1C=C[CH-]C=1.C=1C=C[CH-]C=1 KTWOOEGAPBSYNW-UHFFFAOYSA-N 0.000 description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical class C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 150000002894 organic compounds Chemical class 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 238000004381 surface treatment Methods 0.000 description 2
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 1
- 229910021578 Iron(III) chloride Inorganic materials 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 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
- 230000008901 benefit Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 229910052796 boron Inorganic materials 0.000 description 1
- 125000004122 cyclic group Chemical group 0.000 description 1
- 239000011353 cycloaliphatic epoxy resin Substances 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 239000003822 epoxy resin Substances 0.000 description 1
- -1 ferric chloride Chemical class 0.000 description 1
- IMBKASBLAKCLEM-UHFFFAOYSA-L ferrous ammonium sulfate (anhydrous) Chemical compound [NH4+].[NH4+].[Fe+2].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O IMBKASBLAKCLEM-UHFFFAOYSA-L 0.000 description 1
- 239000011152 fibreglass Substances 0.000 description 1
- 239000012467 final product Substances 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 238000011835 investigation Methods 0.000 description 1
- RBTARNINKXHZNM-UHFFFAOYSA-K iron trichloride Chemical compound Cl[Fe](Cl)Cl RBTARNINKXHZNM-UHFFFAOYSA-K 0.000 description 1
- 238000011031 large-scale manufacturing process Methods 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 125000000325 methylidene group Chemical group [H]C([H])=* 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 229920000647 polyepoxide Polymers 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 239000002990 reinforced plastic Substances 0.000 description 1
- 239000012783 reinforcing fiber Substances 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical class [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 description 1
- 238000010561 standard procedure Methods 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- ZXQVPEBHZMCRMC-UHFFFAOYSA-R tetraazanium;iron(2+);hexacyanide Chemical compound [NH4+].[NH4+].[NH4+].[NH4+].[Fe+2].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-] ZXQVPEBHZMCRMC-UHFFFAOYSA-R 0.000 description 1
- 239000010936 titanium Substances 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
- C08J5/04—Reinforcing macromolecular compounds with loose or coherent fibrous material
- C08J5/06—Reinforcing macromolecular compounds with loose or coherent fibrous material using pretreated fibrous materials
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K5/00—Use of organic ingredients
- C08K5/16—Nitrogen-containing compounds
- C08K5/17—Amines; Quaternary ammonium compounds
- C08K5/18—Amines; Quaternary ammonium compounds with aromatically bound amino groups
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K7/00—Use of ingredients characterised by shape
- C08K7/02—Fibres or whiskers
- C08K7/04—Fibres or whiskers inorganic
- C08K7/06—Elements
-
- D—TEXTILES; PAPER
- D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
- D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
- D01F11/00—Chemical after-treatment of artificial filaments or the like during manufacture
- D01F11/10—Chemical after-treatment of artificial filaments or the like during manufacture of carbon
- D01F11/12—Chemical after-treatment of artificial filaments or the like during manufacture of carbon with inorganic substances ; Intercalation
- D01F11/125—Carbon
-
- D—TEXTILES; PAPER
- D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
- D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
- D01F11/00—Chemical after-treatment of artificial filaments or the like during manufacture
- D01F11/10—Chemical after-treatment of artificial filaments or the like during manufacture of carbon
- D01F11/12—Chemical after-treatment of artificial filaments or the like during manufacture of carbon with inorganic substances ; Intercalation
- D01F11/127—Metals
-
- 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
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S428/00—Stock material or miscellaneous articles
- Y10S428/902—High modulus filament or fiber
-
- 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
- Y10T428/12—All metal or with adjacent metals
- Y10T428/12424—Mass of only fibers
-
- 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
- Y10T428/12—All metal or with adjacent metals
- Y10T428/12444—Embodying fibers interengaged or between layers [e.g., paper, etc.]
-
- 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
- Y10T428/29—Coated or structually defined flake, particle, cell, strand, strand portion, rod, filament, macroscopic fiber or mass thereof
- Y10T428/2913—Rod, strand, filament or fiber
- Y10T428/2918—Rod, strand, filament or fiber including free carbon or carbide or therewith [not as steel]
Definitions
- Carbon fibers offer one other distinct advantage. They are available with a range of mechanical strengths so that fibers still remain. The most significant of these has been associated with the interface area and the development of strong fiber-resin bonds. The weak bond achieved between the matrix resin and the carbon fibers has been the subject of many investigations but still the role of the many interacting factors is not fully understood and is the subject of much debate.
- interlaminar shear strengths which are a measure of the fiberresin bond
- untreated carbon fiber-epoxy resin composites are around 3,500 psi. This compares with values of over 15,000 psi for other reinforcing fibers (glass and boron).
- the general approach to the shear strength problem with carbon fibers has been through fiber surface treatments.
- Graphite fibers present a more difficult problem than other carbon fibers because graphite is more crystalline than other carbon fibers and it is more difficult to treat such fibers in a manner so as to increase shear strength of composites produced from these fibers. Additionally when one has a relatively high modulus fiber (i.e., one with a modulus of about 45,000,000 psi or more) it is more crystalline than low modulus fibers so that high modulus graphite fibers present 'a particularly difficult problem because not only is graphite more crystalline than'other carbon fibers but the high modulus graphite fibers are more crystalline than the lower modulus graphite fibers.
- a relatively high modulus fiber i.e., one with a modulus of about 45,000,000 psi or more
- one object of this invention is to provide graphite fibers.
- a further object of this invention is to provide a relatively fast method'of forming high strength graphite fibers which can be used to form composites.
- a still further object of this invention is to provide a method for forming high modulus graphite fibers which can be relatively strongly bonded to other materials to form composites.
- a highmodulus graphite fiber a chemical compound growing of silicon carbide whiskers on the fibers but it is desirable to have alternate methods to achieve an inwhich contains either Fe, Co, Cr or mixtures thereof (hereinafter called a metal containing compound) and then heating the fiber with the material deposited thereon to a temperature above the decomposition point of the metal containing compound in an inert atmosphere to form the desired treated fiber. This treated fiber is then used to form composites in conventional manners.
- FIG. 1 is a diagram of the apparatus used to apply the metal containing compound onto the fiber and then dry the solvent;
- FIG. 2 is a diagram of the apparatus used to decompose the metal containing compound.
- riac 27 is used to heat tube 24 to aid in drying the solvent.
- the fiber is then guided around pulley 28 and is collected on take up spool 30.
- FIG. 2 is a diagram of the apparatus used to decompose the coated fiber wherein the fiber 32 obtained from the apparatus of FIG. 1 is unwound from spool 34, passes over pulley 36 and enters heating chamber 38 by passing over graphite pulley 40. The fiber exits the chamber by passing over pulley 42. The fiber is heated while in the chamber by resistance heating.
- the electrical circuit includes the portion of the fiber that is between the graphite pulleys, electrical wire 44, variac 46, electrical wire 48, ammeter 50 and additional electrical wire 52.
- the temperature of thefiber is obtained by using an optical pyrometer. Upon passing out of the chamber the fiber passes over pulleys 54 and 56 to take up spool 58.
- Gas inlet 60 is positioned so as to allow the introduction of gas into the entire decomposition system since the decomposition step of this invention is to be conducted in an inert atmosphere.
- Gas outlet 62 is also provided for the egrees of gas that is in the system.
- These fibers are dipped into the treatment solution which is preferably in the form of a dilute solution. It is preferable to apply the'metal containing compound to the fiber from dilute solution because a relatively small amount of pickup is desired. Thus, after the solvent has dried it is desirable to have the metal contain-' ing compound constitute. 0.10 to 3 weight percent of the total fiber plus metal containing compound weight with 0.25-2 weight percent being most preferred. Thus the concentrations of the solutions are relatively low and are under 10 percent by weight with 1-5 weight percent being most preferred. However, although concentration is not critical better results are obtained if the preferred concentrations are used.
- metal containing compound is preferably applied from solution one requirement of the metal containing compounds used in this manner is that they be soluble in some solvent. Furthermore, since the solvent is to be evaporated it is desirable that the solvent be low boiling. Although any metal containing compound or mixtures thereof that are soluble in a solvent which does not attack the fiber can be used there are certain compounds which are preferred. Thus metal containing compounds such as ferric chloride, dicyclopentadienyliron (ferrocene), ammonium ferrocyanide, ferric oxalate, ferric citrate, ferrous ammonium sulphate, chromium acetylacetonate and dicyclopentadienylcobalt have been used in this invention.
- the temperature of the heating step converts the organic compound to carbon char so that a final product will be obtained which comprises a graphite fiber with carbon char and the metal thereon.
- the heating temperature must be at least equal to the decomposition temperature of the organo-metallic compound. Formation of carbon char from compounds is more fully discussed in Ser. No. 238,261 entitled Carbon Fiber Treatment by Joseph M. Augl, James V. Duffy and James V. Larsen filed on the same date herewith and hereby incorporated by reference.
- the decomposition step is conducted in the apparatus of FIG. 2.'The graphite fiber with the metal containing compound or mixture of compounds deposited thereon is heated to the decomposition temperature of the metal containing compound in an inert atmosphere. In the apparatus depicted in FIG. 2 an inert gas is introduced into the heating chamber. The heating of the fiber is affected by passing an electric current through the fiber by contacting the fiber with two graphite electrodesThe fiber are heated to a temperature at least equal to the decomposition temperature of the metal containing compound in order to obtain the proper interaction between the metal and the fiber.
- the upper limit for heating is the temperature at which the fiber itself decomposes or the temperature at which the fiber, any metal on the fiber orcarbon char if any is present react with the inert gases in the heating chamber.
- decomposition temperature of the graphite fiber is meant to include not only the temperature at which the graphite fiber decomposes but also the temperature at which the graphite fiber, or the metal that is deposited on the graphite fiber or carbon char that is on the fiber (if any) react with the inert gas present in the chamber.
- the graphite fibers thus formed have deposits of a metal thereon.
- the metal can be Fe, Co, Cr or mixtures thereof. If a metallo-organic was used to coat the fiber carbon char is also present.
- the graphite fibers thus obtained can then be used to form composites. These fibers are to be used in the same manner as other graphite fibers in the prior art. However, the products obtained using these fibers have better interlaminar shear strengths, due to better fiberresin bonding, than do the prior art graphite fibers.
- metal containing compound is defined as any compound which contains a metal selected from the group consisting of Fe, Co and Cr and mixtures of compounds which. contain any one or combination of these metals.
- Ferrocene is dissolved in toluene to yield about a 2 percent by weight solution.
- the untreated graphite fiber is moved through the dilute solution at a travel rate of 10.5 fpm so that the residence time of the fiber in the solution was about 4 seconds.
- the solvent was dried in the drying tube.
- the dried fiber was then put through the heating tube of FIG. 2.
- the fiber residence time in the heater was about 6 seconds at a temperature of about 800C.
- the fibers thus obtained were fabricated into composites using the standard techniques.
- the fiber obtained above was combined with ERLB 4617 (Union Carbide Corp.) a cycloaliphatic epoxy resin and a curing agent, methylene dianilene.
- the ratio of resin to curing agent was 100:46 parts by weight.
- the composite was cured at 85 C for 4 hours, at 220 C for 3 hours and at 150 C for 16 hours.
- EXAMPLE 2 The same procedure as was used in Example 1 was repeated except a 3 percent by weight solution of FeCl;, in benzene, and another one in water, was used. Again composites formed from the treated fibers were superior to untreated fibers with respect to shear strength.
- a method of treating a graphite fiber comprising:
- organo-metallic compound wherein said metal is selected from the group consisting of Fe, Co, Cr and mixtures thereof;
- organometallic compound is selected from the group consisting of dicyclopentadienyliron, ferric oxalate, ferric citrate, chromium acetylacetonate, dicyclopentadienylcobalt and mixtures thereof.
- organometallic compound is selected from the group consisting of dicyclopentadienyliron, ferric oxalate, ferric citrate, chromium acetylacetonate, dicyclopentadienylcobalt and mixtures thereof.
Abstract
High modulus graphite fiber reinforced composites with improved interlaminar shear strength are provided by depositing a metal containing compound on the graphite fiber, decomposing the metal containing compound at elevated temperatures in an inert atmosphere and then using the fiber to form a composite.
Description
Elnited States Patent [191- Elban et al.
[4 1 Sept. 3, 1974 GRAPHITE FIBER TREATMENT [75] Inventors: Wayne L. Elban, Westminster, Md.;
James V. Larsen, Salt Lake City, Utah [73] Assignee: The United States of America as represented by the Secretary of the Navy, Washington, DC.
[22] Filed: Mar. 27, 1972 [21] Appl. No.: 238,262
[52] US. Cl. 117/46 CA, 29/1822, 75/DIG. l, 75/212,117/118,117/160 R, l17/DIG. 11
[51] Int. Cl. C23c 3/04 [58] Field of Search.... 117/46 CA, 160 R, DIG. 11, 117/71 R, 100 B, 162, 118, 107.2 R, 106 C;
75/DIG. 1, 212; 29/1825 [56] References Cited UNITED STATES PATENTS 3,356,525 12/1967 Gutzeit 117/119 3,627,570 12/1971 Cass 117/DIG. 11
Primary Examiner-Charles E. Van Horn Assistant Examiner-Michael W. Ball Attorney, Agent, or Firm-R. S. Sciascia; J. A. Cooke; M. G. Berger [5 7] ABSTRACT 14 Claims, 2 Drawing Figures GRAPHITE FIBER TREATMENT BACKGROUND OF THE INVENTION Carbon fibers are one of the most promising new materials of recent years. Currently there is considerable interest in these high-modulus, highstrength filaments in developing technology for their use in reinforced plastics composites. The attractiveness of carbon fiber composites arises from the fact that the specific modulus and specific tensile strength are very high compared to conventional engineering materials such as fiberglass composites, titanium, steel and aluminum.
At the present time the relatively high price of the fi- Y bers (one of several hundred dollars per pound) has limited their use to applications where weight saving is at a premium. Price projections, however, for largescale production of the fibers have been as low as five dollars per pound. At lower prices the fibers could profitably be used in many conventional applications such as sports equipment, cables, commercial buildings, bridges, and even automobiles.
Other properties of carbon fibers which are of particular interest are their thermal and chemical stability, electrical conductivity, low coefficients of friction and thermal expansion, high strength retention in tensile cyclic fatigue, and resistance to moisture. Carbon fibers offer one other distinct advantage. They are available with a range of mechanical strengths so that fibers still remain. The most significant of these has been associated with the interface area and the development of strong fiber-resin bonds. The weak bond achieved between the matrix resin and the carbon fibers has been the subject of many investigations but still the role of the many interacting factors is not fully understood and is the subject of much debate. Typically interlaminar shear strengths, which are a measure of the fiberresin bond, in untreated carbon fiber-epoxy resin composites are around 3,500 psi. This compares with values of over 15,000 psi for other reinforcing fibers (glass and boron). The general approach to the shear strength problem with carbon fibers has been through fiber surface treatments.
To date the surface treatment approach most widely used has been oxidation of the fiber surface by a variety of processes. Thus oxidation of graphite fibers with air,
'I-INO and NaOH have been used to give improved fiber-resin bonding. Such treatments have produced various desirable and undesirable results. Most of the oxidation treatments require long exposures to the oxidative environment which, on occasion, cause reductions in the fiber tensile strengths along with the increased composite shear strengths. Furthermore in many cases crease in shear strength with no reduction in tensile strength.
Graphite fibers present a more difficult problem than other carbon fibers because graphite is more crystalline than other carbon fibers and it is more difficult to treat such fibers in a manner so as to increase shear strength of composites produced from these fibers. Additionally when one has a relatively high modulus fiber (i.e., one with a modulus of about 45,000,000 psi or more) it is more crystalline than low modulus fibers so that high modulus graphite fibers present 'a particularly difficult problem because not only is graphite more crystalline than'other carbon fibers but the high modulus graphite fibers are more crystalline than the lower modulus graphite fibers.
Thus research has been conducted in an attempt to find a method of improving the shear strength of composites made with high modulus graphite fibers.
SUMMARY OF THE INVENTION Accordingly one object of this invention is to provide graphite fibers.
method for forming graphite fibers which can be used to form composites. I
A further object of this invention is to provide a relatively fast method'of forming high strength graphite fibers which can be used to form composites.
A still further object of this invention is to provide a method for forming high modulus graphite fibers which can be relatively strongly bonded to other materials to form composites.
- highmodulus graphite fiber a chemical compound growing of silicon carbide whiskers on the fibers but it is desirable to have alternate methods to achieve an inwhich contains either Fe, Co, Cr or mixtures thereof (hereinafter called a metal containing compound) and then heating the fiber with the material deposited thereon to a temperature above the decomposition point of the metal containing compound in an inert atmosphere to form the desired treated fiber. This treated fiber is then used to form composites in conventional manners.
BRIEF DESCRIPTION OF THE DRAWINGS Still other objects and many of the attendant advanta'ges of the present invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings in which:
FIG. 1 is a diagram of the apparatus used to apply the metal containing compound onto the fiber and then dry the solvent; and
FIG. 2 is a diagram of the apparatus used to decompose the metal containing compound.
DESCRIPTION OF THE PREFERRED EMBODIMENT -20. When the fiber'emerges from the treatment solution it is guided around pulley 22 to drying tube 24. Hot air gun 26 is positioned so that it blows hot air into the drying tube so that the solvent if any is evaporated. Va-
FIG. 2 is a diagram of the apparatus used to decompose the coated fiber wherein the fiber 32 obtained from the apparatus of FIG. 1 is unwound from spool 34, passes over pulley 36 and enters heating chamber 38 by passing over graphite pulley 40. The fiber exits the chamber by passing over pulley 42. The fiber is heated while in the chamber by resistance heating. Thus the electrical circuit includes the portion of the fiber that is between the graphite pulleys, electrical wire 44, variac 46, electrical wire 48, ammeter 50 and additional electrical wire 52. The temperature of thefiber is obtained by using an optical pyrometer. Upon passing out of the chamber the fiber passes over pulleys 54 and 56 to take up spool 58. Gas inlet 60 is positioned so as to allow the introduction of gas into the entire decomposition system since the decomposition step of this invention is to be conducted in an inert atmosphere. Gas outlet 62 is also provided for the egrees of gas that is in the system.
These fibers are dipped into the treatment solution which is preferably in the form of a dilute solution. It is preferable to apply the'metal containing compound to the fiber from dilute solution because a relatively small amount of pickup is desired. Thus, after the solvent has dried it is desirable to have the metal contain-' ing compound constitute. 0.10 to 3 weight percent of the total fiber plus metal containing compound weight with 0.25-2 weight percent being most preferred. Thus the concentrations of the solutions are relatively low and are under 10 percent by weight with 1-5 weight percent being most preferred. However, although concentration is not critical better results are obtained if the preferred concentrations are used.
Since the metal containing compound is preferably applied from solution one requirement of the metal containing compounds used in this manner is that they be soluble in some solvent. Furthermore, since the solvent is to be evaporated it is desirable that the solvent be low boiling. Although any metal containing compound or mixtures thereof that are soluble in a solvent which does not attack the fiber can be used there are certain compounds which are preferred. Thus metal containing compounds such as ferric chloride, dicyclopentadienyliron (ferrocene), ammonium ferrocyanide, ferric oxalate, ferric citrate, ferrous ammonium sulphate, chromium acetylacetonate and dicyclopentadienylcobalt have been used in this invention. It should be noted that when the metal containing compound is an organic compound the temperature of the heating step converts the organic compound to carbon char so that a final product will be obtained which comprises a graphite fiber with carbon char and the metal thereon. To form carbon char the heating temperature must be at least equal to the decomposition temperature of the organo-metallic compound. Formation of carbon char from compounds is more fully discussed in Ser. No. 238,261 entitled Carbon Fiber Treatment by Joseph M. Augl, James V. Duffy and James V. Larsen filed on the same date herewith and hereby incorporated by reference.
The decomposition step is conducted in the apparatus of FIG. 2.'The graphite fiber with the metal containing compound or mixture of compounds deposited thereon is heated to the decomposition temperature of the metal containing compound in an inert atmosphere. In the apparatus depicted in FIG. 2 an inert gas is introduced into the heating chamber. The heating of the fiber is affected by passing an electric current through the fiber by contacting the fiber with two graphite electrodesThe fiber are heated to a temperature at least equal to the decomposition temperature of the metal containing compound in order to obtain the proper interaction between the metal and the fiber. The upper limit for heating is the temperature at which the fiber itself decomposes or the temperature at which the fiber, any metal on the fiber orcarbon char if any is present react with the inert gases in the heating chamber. Thus within the context of this invention the term decomposition temperature of the graphite fiber is meant to include not only the temperature at which the graphite fiber decomposes but also the temperature at which the graphite fiber, or the metal that is deposited on the graphite fiber or carbon char that is on the fiber (if any) react with the inert gas present in the chamber.
The graphite fibers thus formed have deposits of a metal thereon. The metal can be Fe, Co, Cr or mixtures thereof. If a metallo-organic was used to coat the fiber carbon char is also present.
The graphite fibers thus obtained can then be used to form composites. These fibers are to be used in the same manner as other graphite fibers in the prior art. However, the products obtained using these fibers have better interlaminar shear strengths, due to better fiberresin bonding, than do the prior art graphite fibers.
It should be noted that within the meaning of this invention the term metal containing compound is defined as any compound which contains a metal selected from the group consisting of Fe, Co and Cr and mixtures of compounds which. contain any one or combination of these metals.
The general nature of the invention having been set forth, the following example is presented as a specific illustration thereof. It will be understood that the invention is not limited to this specific example but is susceptible to various modifications that will be recognized by one of ordinary skill in the art.
EXAMPLE 1 Ferrocene is dissolved in toluene to yield about a 2 percent by weight solution. The untreated graphite fiber is moved through the dilute solution at a travel rate of 10.5 fpm so that the residence time of the fiber in the solution was about 4 seconds. The solvent was dried in the drying tube. The dried fiber was then put through the heating tube of FIG. 2. The fiber residence time in the heater was about 6 seconds at a temperature of about 800C.
The fibers thus obtained were fabricated into composites using the standard techniques. Thus the fiber obtained above was combined with ERLB 4617 (Union Carbide Corp.) a cycloaliphatic epoxy resin and a curing agent, methylene dianilene. The ratio of resin to curing agent was 100:46 parts by weight. The composite was cured at 85 C for 4 hours, at 220 C for 3 hours and at 150 C for 16 hours.
EXAMPLE 2 The same procedure as was used in Example 1 was repeated except a 3 percent by weight solution of FeCl;, in benzene, and another one in water, was used. Again composites formed from the treated fibers were superior to untreated fibers with respect to shear strength.
Obviously, numerous modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described herein.
What is claimed as new and desired to be secured by Letters Patent of the United States is:
1. A method of treating a graphite fiber comprising:
depositing on a graphite fiber a organo-metallic compound wherein said metal is selected from the group consisting of Fe, Co, Cr and mixtures thereof; and
heating the graphite fiber with said organo-metallic compound deposited thereon to a temperature in excess of the decomposition temperature of said organo-metallic compound but below the decomposition temperature of the fiber.
2. The fiber obtained by the process of claim 1.
3. In composites comprising graphite fibers the improvement comprising incorporating the graphite fiber of claim 2.
4. The method of claim 1 wherein said graphite fiber is a high modulus fiber.
5. The method of claim 4 wherein said organometallic compound is deposited on said high modulus graphite fiber from a solution and the solvent is evaporated prior to decomposition.
6. The method of claim 5 wherein said organometallic compound is selected from the group consisting of dicyclopentadienyliron, ferric oxalate, ferric citrate, chromium acetylacetonate, dicyclopentadienylcobalt and mixtures thereof.
7. The fiber obtained by the process of claim 4.
8. In composites comprising graphite fibers the improvement comprising incorporating the graphite fiber of claim 7.
9. The fiber obtained by the process of claim 6.
10. In composites comprising graphite fibers the improvement comprising incorporating the fiber of claim 11. The method of claim 1 wherein said organometallic compound is deposited on said graphite fiber from a solution and the solvent is evaporated prior to decomposition.
12. The method of claim 11 wherein said organometallic compound is selected from the group consisting of dicyclopentadienyliron, ferric oxalate, ferric citrate, chromium acetylacetonate, dicyclopentadienylcobalt and mixtures thereof.
13. The fiber obtained by the process of claim I2.
14. In composites comprising graphite fibers the improvement comprising incorporating the fiber of claim 13.
Claims (13)
- 2. The fiber obtained by the process of claim 1.
- 3. In composites comprising graphite fibers the improvement comprising incorporating the graphite fiber of claim 2.
- 4. The method of claim 1 wherein said graphite fiber is a high modulus fiber.
- 5. The method of claim 4 wherein said organo-metallic compound is deposited on said high modulus graphite fiber from a solution and the solvent is evaporated prior to decomposition.
- 6. The method of claim 5 wherein said organo-metallic compound is selected from the group consisting of dicyclopentadienyliron, ferric oxalate, ferric citrate, chromium acetylacetonate, dicyclopentadienylcobalt and mixtures thereof.
- 7. The fiber obtained by the process of claim 4.
- 8. In composites comprising graphite fibers the improvement comprising incorporating the graphite fiber of claim 7.
- 9. The fiber obtained by the process of claim 6.
- 10. In composites comprising graphite fibers the improvement comprising incorporating the fiber of claim 9.
- 11. The method of claim 1 wherein said organo-metallic compound is deposited on said graphite fiber from a solution and the solvent is evaporated prior to decomposition.
- 12. The method of claim 11 wherein said organo-metallic compound is selected from the group consisting of dicyclopentadienyliron, ferric oxalate, ferric citrate, chromium acetylacetonate, dicyclopentadienylcobalt and mixtures thereof.
- 13. The fiber obtained by the process of claim 12.
- 14. In composites comprising graphite fibers the improvement comprising incorporating the fiber of claim 13.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
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US00238262A US3833402A (en) | 1972-03-27 | 1972-03-27 | Graphite fiber treatment |
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Application Number | Priority Date | Filing Date | Title |
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US00238262A US3833402A (en) | 1972-03-27 | 1972-03-27 | Graphite fiber treatment |
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US3833402A true US3833402A (en) | 1974-09-03 |
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US00238262A Expired - Lifetime US3833402A (en) | 1972-03-27 | 1972-03-27 | Graphite fiber treatment |
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Cited By (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4072516A (en) * | 1975-09-15 | 1978-02-07 | Fiber Materials, Inc. | Graphite fiber/metal composites |
US4311630A (en) * | 1979-04-17 | 1982-01-19 | California Institute Of Technology | Gasifiable carbon-graphite fibers |
US4314003A (en) * | 1977-12-29 | 1982-02-02 | Union Carbide Corporation | Method of incorporating multifilament strands of carbon fibers into cement to produce reinforced structures having improved flexural strengths |
US4481249A (en) * | 1981-02-21 | 1984-11-06 | Bayer Aktiengesellschaft | Metallized carbon fibres and composite materials containing these fibres |
EP0136497A2 (en) * | 1983-09-06 | 1985-04-10 | Nikkiso Co., Ltd. | A process for preparing fine carbon fibers in a gaseous phase reaction |
US4518632A (en) * | 1984-04-18 | 1985-05-21 | The United States Of America As Represented By The Secretary Of The Navy | Metallized synthetic cable |
EP0158853A2 (en) * | 1984-04-20 | 1985-10-23 | Nikkiso Co., Ltd. | A process for preparing carbon fibers in gas phase growth |
WO1988003854A1 (en) * | 1986-11-26 | 1988-06-02 | Sundstrand Corporation | Composite, method of forming a composite, and article of manufacture |
US5099667A (en) * | 1989-06-16 | 1992-03-31 | Lonza Ltd. | System for suspending and applying solid lubricants to tools or work pieces |
US5244748A (en) * | 1989-01-27 | 1993-09-14 | Technical Research Associates, Inc. | Metal matrix coated fiber composites and the methods of manufacturing such composites |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3356525A (en) * | 1963-11-18 | 1967-12-05 | Hitco Corp | Metal carbide formation on carbon fibers |
US3627570A (en) * | 1970-05-28 | 1971-12-14 | Monsanto Res Corp | Heat treatment of graphite fibers |
-
1972
- 1972-03-27 US US00238262A patent/US3833402A/en not_active Expired - Lifetime
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3356525A (en) * | 1963-11-18 | 1967-12-05 | Hitco Corp | Metal carbide formation on carbon fibers |
US3627570A (en) * | 1970-05-28 | 1971-12-14 | Monsanto Res Corp | Heat treatment of graphite fibers |
Cited By (13)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4072516A (en) * | 1975-09-15 | 1978-02-07 | Fiber Materials, Inc. | Graphite fiber/metal composites |
US4314003A (en) * | 1977-12-29 | 1982-02-02 | Union Carbide Corporation | Method of incorporating multifilament strands of carbon fibers into cement to produce reinforced structures having improved flexural strengths |
US4311630A (en) * | 1979-04-17 | 1982-01-19 | California Institute Of Technology | Gasifiable carbon-graphite fibers |
US4481249A (en) * | 1981-02-21 | 1984-11-06 | Bayer Aktiengesellschaft | Metallized carbon fibres and composite materials containing these fibres |
EP0136497A3 (en) * | 1983-09-06 | 1985-08-14 | Nikkiso Co., Ltd. | A process for preparing fine carbon fibers in a gaseous phase reaction |
EP0136497A2 (en) * | 1983-09-06 | 1985-04-10 | Nikkiso Co., Ltd. | A process for preparing fine carbon fibers in a gaseous phase reaction |
US4518632A (en) * | 1984-04-18 | 1985-05-21 | The United States Of America As Represented By The Secretary Of The Navy | Metallized synthetic cable |
EP0158853A2 (en) * | 1984-04-20 | 1985-10-23 | Nikkiso Co., Ltd. | A process for preparing carbon fibers in gas phase growth |
EP0158853A3 (en) * | 1984-04-20 | 1987-04-01 | Nikkiso Co., Ltd. | A process for preparing carbon fibers in gas phase growth |
WO1988003854A1 (en) * | 1986-11-26 | 1988-06-02 | Sundstrand Corporation | Composite, method of forming a composite, and article of manufacture |
US4817853A (en) * | 1986-11-26 | 1989-04-04 | Sundstrand Corporation | Composite, method of forming a composite, and article of manufacture |
US5244748A (en) * | 1989-01-27 | 1993-09-14 | Technical Research Associates, Inc. | Metal matrix coated fiber composites and the methods of manufacturing such composites |
US5099667A (en) * | 1989-06-16 | 1992-03-31 | Lonza Ltd. | System for suspending and applying solid lubricants to tools or work pieces |
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