DE1954480C - Process for depositing a boron coating on a carbon fiber - Google Patents

Description

the volume ratio between boron halide (boron trichloride) and hydrogen was in the upper range of the reactor at 1 / 2.5 and in the lower region of the reactor at 1 / 1.6.

For example, a boron deposit of 15.24 microns is produced on a 25.4 micron carbon fiber so that the total fiber is 55.88 microns thick. The boron precipitate of such a fiber has an average tensile strength in excess of 42,200 kg / cm * and the composite fiber has an average tensile strength of 31,600 kg / cm ² . The density of the boron-carbon fiber is 2.25 g / cm ³ , the modulus of elasticity of the boron precipitate is 4.22 · 10 «kg / cm *.

1 sheet of drawings

Claims (6)

1 2 claims: moderate, smooth coating without fiber breakage is achieved. 1. Process for continuous precipitation in the case of the underlying invention An amorphous boron coating on a detailed investigation could namely overheat Carbon fiber in a gas atmosphere, S rashly found to be the above from a mixture of boron halide mentioned irregularities in the coating of and hydrogen, thereby marked fractures of the carbon fiber, which come to be called net that the carbon fiber only have such short points in the fiber and are uneven Time is exposed to the gas atmosphere that growth phenomena (expansion) of the boron result in a uniform, smooth coating without fiber breakage in the coating. This realization made possible will. clear the next step in the invention, fiber breaks 2. The method according to claim 1, characterized in that the carbon and the resultant consequence that the duration of the action can be avoided by the fact that the carbon ends Gas atmosphere on the carbon fiber maxi- mum fiber only for a specific, short period of time 5 seconds. 15 atmosphere. 3. The method according to claim 1, characterized in that the duration of the action of the gas atmosphere Indicates that the carbon fiber in itself is on the carbon fiber preferably as much as is known by electric current conduction times 5 seconds. The carbon fiber is doing this is heated by the fiber. expedient in a manner known per se by elec- 4. The method according to claim 1, characterized in that ge 20 tric current conduction through the fiber is heated,
indicates that carbon fibers with a diameter between 12.7 and 50.8 microns, preferably carbon fibers with a through, knife between 12.7 and 50.8 microns are used. 5. The method according to claim 1, characterized ge your temperature is between 1100 and 1300 ° C, indicates that the temperature of the carbon 25 is preferably between 1250 and 1275 ° C, kept the fiber between 1100 and 1300 ⁰ C, preferably favorable are carbon fibers with a circular way between 1250 and 1275 ° C, is kept. Cross-section and a resistance between 197 and 6. The method according to claim 1, characterized in 985 ohms / cm. indicates that a carbon fiber with circular An embodiment of a reactor for through- shaped cross-section and a resistor 30 guide the method according to the invention is in the between 197 and 985 ohms / cm is used. Drawing illustrates. The reactor 10 contains a tubular vessel 12 with double gas inlets 14, 16 and 18, 20 on both ends of the vessel and one common 35 outlet 22 in the middle of the vessel. Through the The invention relates to a method for conti- lasse 14 and 18 is hydrogen and through the Renal deposition of an amorphous excess 16, 20 boron halide supplied. The vessel 12 on top of a heated carbon fiber in one is made of quartz, for example. Gas atmosphere, consisting of a mixture of The gas inlets are electrically conductive with metallic Boron halide and hydrogen. 40 see plugs 24, 26 connected to the vessel 12 It is known to terminate the ends of a boron halide-water and flow the carbon atmosphere apply a boron coating on heated fiber 50. The plugs 24, 26 contain made of metal wire, for example a tungsten wire, recesses 30, 32 with a sealing medium knock down. Boron 34 produced in this way, for example mercury, are filled. Through Fibers are characterized by their high strength, and good elasticity Properties and excellent temperature control of the carbon fiber 50 sealed and temperature resistance out. Their disadvantage lies in the fact that, on the other hand, the electrical contact with the carbon is relatively high in cost of tungsten. fabric fiber made. Lines 23, 25 connect the In an effort to replace the tungsten wire with a plug 24, 26 with a direct current source 36 using cheaper material, boron 50 has already been interposed with a potentiometer 56.
from a boron halide-hydrogen atmosphere. The plugs 24, 26 are further deposited on their periphery by heated carbon fiber. It is provided with a groove 38, which is connected to the recess at, however, irregular, bamboo-like 30 or 32 and is likewise filled with nodes made of boron around the carbon fiber, the sealing medium 34 is filled. As a result, the properties of the end product will be significantly impaired. Despite extensive attempts, the wall of the vessel 12 was sealed,
Until the filing date, it was unknown what this boron The plugs 24, 26 contain a central opening node were based on and how they could be avoided. 44 or 46, which is large enough to pass the carbon. Interestingly, these knots occur in fiber 50, which, on the other hand, do not occur as a boron coating on metal fibers. 60 is small enough to allow the sealing medium 34 through The invention is therefore based on the object of keeping surface tension in the recess, To develop a method that the continuous die carbon fiber 50 is fed from a roll 52 Production of a uniform, knot-free down-drawn, passed through the reactor 10 Impact of an amorphous boron coating on a reel 54 and wound up again. At the heated carbon fiber allows. 65 passage through the reactor 10 is carried out on the According to the invention, this object is achieved by giving heated carbon fiber an amorphous boron coating solves that the carbon fiber is only knocked down for so short a time, is exposed to the gaseous atmosphere, that a direct For optimum precipitate