Two-dimensional fiber/boron nitride nanotube multistage reinforcement and preparation method thereof

[0026] The preparation method of the multi-stage reinforcement of the present invention, the specific steps are as follows:

[0027] 1) Iron ball mill tank and iron ball mill:

[0028] ①According to the mass ratio of balls to 1-150:1, put the boron source precursor powder and iron grinding balls in the iron ball milling tank, add non-aqueous solvent as the ball milling medium, or pass NH3 without adding liquid medium for ball milling Protection, ball milling at 150-440rpm for 24-150h;

[0029] ②The precursor after ball milling is added to the non-aqueous solvent consistent with the ball milling medium (if no liquid ball milling medium is added during the ball milling, a non-aqueous solvent can be added directly) to form a slurry, and the two-dimensional fiber fabric is cut. Put it into the above-mentioned slurry for dipping, and perform ultrasound for 1 hour during the dipping process to ensure good suspension of the slurry. Put the impregnated two-dimensional fiber fabric into a drying box and dry it at 85°C for 1 hour.

[0030] 2) Non-ferrous ball mill tank and non-ferrous ball mill:

[0031] ①According to the mass ratio of balls to 1-150:1, put the boron source precursor powder and non-ferrous grinding balls in a non-ferrous ball milling tank, add a non-aqueous solvent as the ball milling medium, and ball mill at 150-440rpm for 24-150h ;

[0032] ②The precursor after ball milling is added to the non-aqueous solvent and catalyst consistent with the ball milling medium to prepare a slurry, and the two-dimensional fiber fabric is cut out and immersed in the above slurry. During the dipping process, ultrasound is performed for 1 hour to ensure a good slurry Suspension. Put the impregnated two-dimensional fiber fabric into a drying box and dry it at 85°C for 1 hour;

[0033] ③Put the impregnated and dried two-dimensional fiber fabric into a tube furnace, first pass in nitrogen gas, wait for the temperature of the tube furnace to rise to the reduction temperature of 500-1400℃, pass in a reducing atmosphere, flow 50-300sccm, holding time For 5-120 minutes, the catalyst is reduced to metal nanoparticles, then the reducing atmosphere is closed, and then nitrogen is introduced to cool to room temperature.

[0034] 3) Put the two-dimensional fiber fabric obtained through step 1) or 2) into a high-pressure nitriding furnace, and pass high-purity nitrogen until the pressure in the high-pressure furnace reaches 0.5-8MPa, and the temperature of the high-pressure furnace is increased to the growth temperature 900-1600°C, heat preservation for 0.5-5h, after cooling to room temperature, a two-dimensional fiber/boron nitride nanotube multi-level reinforcement is obtained.

[0035] In steps 1) and 2), the boron source precursor powder is boron powder or boron nitride powder;

[0036] In steps 1) and 2), the non-aqueous solvent is ethanol or acetone;

[0037] In steps 1)-3), in the two-dimensional fiber fabric, the fibers used are carbon fiber, silicon carbide fiber, boron nitride fiber, alumina fiber or a combination thereof; the fiber diameter is 5-15 microns;

[0038] In steps 1)-3), in the two-dimensional fiber fabric, an interface layer is deposited on the fiber surface, and the interface layer includes a SiC interface, a PyC interface, a BN interface, and a Si 3 N 4 Interface, ZrC interface, ZrB 2 Interface, HfC interface, HfB 2 Interface, TaC interface, TiC interface or composite interface composed of the above interfaces; the thickness of the interface layer is 100-1500 nm;

[0039] In steps 1) and 2), the ball material mass ratio is 1-150:1, preferably the ball material mass ratio is 20-100:1;

[0040] In steps 1) and 2), the ball mill speed is 150-440rpm, preferably 250-400rpm;

[0041] In steps 1) and 2), the milling time is 24-150h, preferably 50-120h;

[0042] In step 1), the iron ball mill tank is a stainless steel ball mill tank or a cemented carbide ball mill tank;

[0043] In step 1), the iron grinding balls are respectively stainless steel grinding balls or cemented carbide grinding balls;

[0044] In step 2), the non-ferrous ball milling tank is a nylon ball milling tank, polyurethane ball milling tank, agate ball milling tank, ceramic ball milling tank, or polytetrafluoroethylene ball milling tank;

[0045] In step 2), the non-ferrous grinding balls are zirconia grinding balls, agate grinding balls, alumina grinding balls, tungsten carbide grinding balls or silicon nitride grinding balls;

[0046] In step 2), the catalyst is cobalt nitrate, nickel nitrate or iron nitrate;

[0047] In step 2), the reducing atmosphere is hydrogen, carbon monoxide or ammonia;

[0048] In step 2), the reducing atmosphere flow rate is 50-300 sccm, preferably 80-150 sccm;

[0049] In step 2), the reduction temperature is 500-1400°C, preferably 500-1000°C;

[0050] In step 2), the reduction holding time is 5-120min, preferably 8-60min;

[0051] In step 3), the pressure of the nitrogen atmosphere is 0.5-8MPa, preferably 1-4MPa;

[0052] In step 3), the growth temperature is 900-1600°C, preferably 1200-1500°C;

[0053] In step 3), the holding time is 0.5-5h, preferably 0.5-2h.

[0054] In the present invention, the boron source precursor powder can pass through the iron ball milling tank and the iron ball milling route, namely steps 1) and 3), to finally obtain a two-dimensional fiber/boron nitride nanotube multi-level reinforcement. In this process route, the catalyst required for the growth of boron nitride nanotubes is the elemental metal Fe and Ni incorporated in the precursor during the iron ball milling tank and the iron ball milling process.

[0055] In the present invention, the boron source precursor powder can also pass through a non-ferrous ball milling tank and a non-ferrous ball milling route, namely steps 2) and 3), to finally obtain a two-dimensional fiber/boron nitride nanotube multi-level reinforcement. In this process route, the catalyst required for the growth of boron nitride nanotubes comes from the reduction of nitrate added after ball milling into metal nanoparticles in a reducing atmosphere.

[0056] The beneficial effect of the present invention is that the two-dimensional fiber/boron nitride nanotube multi-level reinforcement is innovatively prepared for the first time through the ball milling-high pressure nitriding or ball milling-reduction-high pressure nitriding process. The preparation process is simple, the raw material cost is low, safe and easy to obtain, and the boron nitride nanotubes in the obtained multi-level reinforcement are uniformly coated on the fiber surface.

[0057] Such as figure 1 Shown is the specific process route adopted in the present invention. The precursor powder of the boron source is milled into a slurry through an iron ball milling tank and an iron ball mill, impregnated with a two-dimensional fiber fabric, and dried and placed in a high pressure nitriding furnace. Perform high-pressure nitriding in the medium, or pass the boron source precursor powder through a non-ferrous ball mill tank and a non-ferrous ball mill, then add a catalyst to prepare a slurry, impregnate the two-dimensional fiber fabric, and put it into a tube furnace after drying A reducing atmosphere is introduced into the medium, the catalyst is reduced, and then placed in a high-pressure nitriding furnace for high-pressure nitriding. Finally, the boron nitride nanotubes as the nano-reinforcing phase are grown on the two-dimensional fiber fabric to obtain the multi Grade reinforcement.

[0058] Such as figure 2 Shown is the Raman spectrum of boron nitride nanotubes in the multi-level reinforcement prepared in Example 1 of the present invention, and the result is shown at 1368.96 cm -1 There is a very sharp single peak, which corresponds to the E of h-BN 2g The in-plane stretching vibration mode indicates that the grown one-dimensional nanomaterial is hexagonal boron nitride with B and N atoms arranged in a hexagonal structure.

[0062] Example 1:

[0063] According to the ball-to-material mass ratio of 20:1, the boron powder and stainless steel grinding balls are placed in a stainless steel ball milling tank, ethanol is added as the ball milling medium, and the ball milling is performed at 400 rpm for 80 hours. The precursor after ball milling is added to a proper amount of ethanol to prepare a slurry, a small piece of two-dimensional carbon fiber fabric is cut out, and it is immersed in the slurry, and the dipping process is ultrasonicated for 1 hour to ensure good suspension of the slurry. Then put the impregnated two-dimensional carbon fiber fabric into a drying box and dry it at 85°C for 1 hour. Finally, the impregnated and dried two-dimensional carbon fiber fabric is put into a high-pressure nitriding furnace, and high-purity nitrogen is introduced until the pressure in the high-pressure furnace reaches 2MPa, and the temperature of the high-pressure furnace is increased to 1400°C for the growth temperature of boron nitride nanotubes, After cooling to room temperature for 2 hours, boron nitride nanotubes are grown in situ on the fiber surface to obtain a two-dimensional carbon fiber/boron nitride nanotube multi-level reinforcement.

[0064] Example 2:

[0065] When the precursor powder is ball milled, the liquid ball milling medium is not added, and only NH3 is passed in for protection. The others are the same as in Example 1. As a result, a two-dimensional fiber/boron nitride nanotube multi-level reinforcement is obtained.