DE2300510A1 - REINFORCEMENT FIBER FOR TITANIUM AND NICKEL MATRICES - Google Patents

Description

United Aircraft Corporation East Hartford, Conn./USA

Reinforcement fiber for titanium and ITicke! Matrices

It is well known that threads with a silicon carbide surface, such as threads made of silicon carbide or made of boron or carbon and with silicon carbide coated can be used as reinforcement materials in composite structures. Particularly boron threads coated with silicon carbide are used for this, as described, for example, in U.S. Patent 3,622,369. In industry the usefulness of Threads with a silicon carbide surface as reinforcement in resin matrices and certain metal matrices, e.g. Aluminum and Magnesium Matrices, Generally Recognized. Though the sea activity of silicon carbide is lower than that of boron, for example, but it is still sufficient high that low during the manufacture of composite filament reinforced metal products Temperatures or short times

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230051Π

must be grounded to prevent fiber degradation. This also makes the selection of the matrix material and limits the temperature at which the structure can be used.

As a result, in powder metallurgy or other processes in which titanium or nickel is hot-pressed with threads having a silicon carbide surface, such as, for example, boron threads coated with silicon carbide, pressing temperatures below SCO ⁰ C have been used to prevent degradation of 1er fibers. While temperatures below 8CC ^C C can be used in such a hot press technique, they require exceptionally high pressures which are not practical for making large pieces. As a result, the full utilization of the filaments provided with silicon carbide surfaces depends on the development of techniques with which the compatibility between the fiber and the matrix can be improved in the manner discussed above.

Thus, the present invention relates to. compound Threads and especially threads with a silicon carbide surface, such as threads made entirely of silicon carbide consist of boron threads coated with silicon carbide, carbon threads coated with silicon carbide and the like, which are provided with a thin adhesive coating made of titanium carbide .. I

It has been found that titanium carbide works with substrates that have a silicon carbide surface, as well as with such metal matrix materials as titanium and mckel is compatible. It was further found that a titanium carbide coating with a thickness of only 0.00075 mm a thread with a silicon carbide surface not only gives the thread an oxidation resistance but also

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a diffusion barrier between the substrates with silicon carbide surface and such Xstrixmetallen v; ie Titan unii Nickel creates, so that the fermentation of barrels in the process reduces is where temperatures above SCCC are used.

Titanium carbide is beneficial in several ways. Ba it its main function as surface protection for threads with silicon carbide surface, such as 3. those with silicon carbide coated boron threads, which have a high modulus, high strength and low density, are already in fulfilled a very low strength, the weight is only slightly increased due to its addition. Since there is also no disproportion ir when using titanium carbide; thermal expansion coefficients there were in this Regarding in practice no difficulties-encountered, and especially because the file is very thin.

The invention will now be explained in more detail with reference to the accompanying drawings.

In the drawings show:

FIG. 1 shows a simple representation of a device which is used in the production of the threads according to the invention coated with titanium carbide; and

Figure 2 is an enlarged section through an inventive

Thread.

3emä3 Figure 1 is the titanium carbide coating on a through Resistance heating heated thread 2 with silicon carbide surface which is drawn down through a reactor which consists of a tubular container 6 consists of the two gas inlets 8 and 1C at the top and has a single gas outlet 12 at the lower end. Kühiv: a ε s only off is fed to the reactor through inlet 8. The inlet 10 is used for the introduction of a reactant gas

Mixture used that contains methane and titanium chloride (TiCl ₂ ,). The container can be made of Pyrex, although various other materials such as Vyccr and quartz have also been found to be satisfactory. Gas inlets B and 10 and outlet 12 penetrate and electrically connect to metal "metal" terminations 14 and 16 of the container. They provide a convenient means by which energy can be added to the wire for resistance heating purposes.

The terminations are each equipped with a 2G or 22, each containing a suitable conductive sealant 24-, such as mercury, which is twice as large Purpose of a gas seal around the wire where it closes the eni penetrates, and fulfills an electrical contact between the running wire and the respective end closure. The sealing closures are in turn electrical through the tubes IG and 12 und'die lines 26 and 28 with a suitable DC bromine source 30 connected. The upper closure 14-possesses a circumferential groove 34-, which with the mercury in the Lowering 2C is connected by a bore 36, so dap a Circumferential seal is created around the closure. The seal between the end closure 16 and the lower end of the container 6 takes place through the ring-shaped designated 3S Part of the mercury.

The individual closures are each equipped with a central opening 4-0 or 4-2, which are so large that the Wire 2 can go through freely, but in turn in combination with the wire are so small that the mercury is retained by the surface tension.

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The hydrogen admitted through inlet 8 enters the reaction chamber "directly at the wire entry at the end closure 14 and is primarily used for Cooling purposes. As can be seen in Figure 2, passage through the reactor results in a composite thread which consists of a substrate having a carbide surface 46 and a thin adhesive coating made of titanium carbide 45. Following the formation of the titanium carbide layer, the threads are consolidated and with the desired • Matrix material connected by hot pressing.

The invention will now be explained in more detail with reference to the following examples.

example 1

In a reactor of the type shown, which had a 203 long and 25 mm wide Fyrex tube, a titanium carbide coating was produced on a silicon carbide-coated boron thread using a reactant gas mixture of methane, hydrogen and titanium chloride, the boron thread being heated to 115C ° C and ran at a speed of 182.9 m / h (residence time in the reactor: 4 seconds). These substrate threads are commercially available from the Hamilton Standard Division of United Aircraft Corporation. They consist of boron threads with a diameter of C, 1 mm thick, which have a 0.004mm thick silicon carbide coating and a final tensile strength of 2870C kg / cm ^. The total gas flow through the reactor was kept at 50 oc ml / min. The methane was saturated with TiCl _{2 by} passing it through TiCl 2, which was located in a container, a cooler above the container being cooled ^{with tap water at 18 to 20 ° C}

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■ and maintaining a pressure of 0.07 kg / cm in the container became. Hydrogen was introduced into the reactor separately. The ratio of hydrogen to methane was up held at 5i1.

The presence of a titanium carbide coating was confirmed by X-ray diffraction ensured. The electrical conductivity measurements showed a remarkable decrease of resistance. The Eel ag was thin (0.00075 now) and adhered to the coated thread. This showed a final tensile strength of 25200 kg / cm. .

Example 2 .

Ss became the same device and conditions as used in Example 1, except that the substrate thread speed 73 »2 m / st (reactor residence time: 10 seconds), the substrate temperature 1050 ° C and the hydrogen / methane ratio 15: 1 was. The adhering titanium carbide coating was approximate C, 0CC5 mm thick. The coated composite filament exhibited a final tensile strength of. 21CCO kg / cm

Example 3 ι

The same apparatus and conditions as in Example 2 were used, except that the substrate temperature was 11C0 ° C and the hydrogen / kethane ratio was 5: 1. It; Adhesive titanium carbide coatings approximately 0.0005 mm thick were produced on 10 samples. The composite coated filaments showed a final tensile strength of 26040 kg / cm ² . '. "

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BeisDiel 4

and
The same device | the same conditions were used as in Example 1, except that the substrate thread speed -464 «n / st (reactor residence time: 16 seconds), the substrate operating temperature was 110 ° C. and the hydrogen / hethane ratio was 25 = 1. The titanium carbide coating had a similar thickness and quality as that of Example 1. The thread had a final tensile strength of 2275 ° C. kg / c ~ i ~.

example 3

Example 4 was repeated except that the substrate temperature was 1IpC ⁰ O and the hydrogen / hethane ratio was 15: 1. A pad coated with titanium carbide had a final tensile strength of 2555 ° C. kg / cm ² .

Example 6

In the reactor device of Example 1, a thin, adhesive titanium carbide coating was produced on a silicon carbide-coated carbon thread (carbon monofilament with a circular cross-section of 0.025 mm diameter, available from Great Lakes Carbon Corp.), the thread being ^{heated to 1100 °} C. and through a reactant gas mixture of methane, hydrogen and titanium chloride 121 passed through the reactor at a rate _{vc: 1} '~ / si (residence time: Λβ sec). The total gas flow through the reactor was kept at 500 tol / ain and the hydrogen / methane ratio at 5: 1. The methane was saturated with TiCl ^ as in Example 1.

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Example 7

Using the apparatus and conditions of Example 6, a titanium carbide coating was formed on a silicon carbide filament manufactured (1O0A strong continuous thread from from Dow Corning or General Technologies Corporation).

In the course of the tests, the wire temperatures, the speeds and the gas compositions were changed. It should be noted that the ultimate tensile strength of the thread generally increases as the temperature increases, increases as the gas ratio increases, and decreases as the residence time increases. At a residence time of 4 see no TiC coating was observed by X-ray diffraction, when the wire temperature 1O5O ° C and the gas ratio of 25: was 1 or when the wire temperature 1100 ⁰ C and the gas ratio is 15: 1. Similarly, the residence time was 10 to see observed no covering, when the temperature was maintained at 1150 ⁰ C and the gas ratio 25ϊ1 with an increase. Finally, no deposit was observed even at a residence time of 16 lake, when the temperature of 1050 ⁰ C and the gas ratio of 5: 1.

As indicated in the examples above, the deposition of titanium carbide gives a small reduction in the average Strength of the composite thread. However, this reduction is only minor if the correct process conditions are used be respected. For example, the parameters given in example 3 only result in a

strength reduction by 7% (from 28700 to 26040 kg / cm). This reduction is in view of the fact that the threads coated with TiC allow a connection with titanium or nickel matrices, which normally attack and destroy threads with silicon carbide surface ^{at temperatures above 800 ° C.,}

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not "significant. In this case, coated with titanium carbide filaments were subjected to a test for compatibility in nickel and Titannatrices. by hot pressing of threads with a Carbidoberflache coated with TIG, with an Ti-powder at 900 ⁰ C and 350 kg / cm "during 30 nin. composite products were made. Further composite products were produced by hot pressing with Ni powder at 850 ° C. and 350 kg / cm for 3 minutes. In all cases, the threads coated with TiC were not attacked by either the titanium or the iTickel.

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Claims (2)

Claims 1. Compound thread, for use as reinforcement in titanium and hickel matrices, made from a thread substrate with a surface which consists essentially of silicon carbide, characterized in that it has a thin adhesive outer layer consisting essentially of titanium carbide. 2. Composite thread according to claim 1, characterized in that the thread substrate made of silicon carbide, consists of boron coated with silicon carbide or of carbon coated with silicon carbide. 3 · Composite thread according to claim 1, characterized characterized in that the thread substrate consists of boron coated with silicon carbide. 309828/1096