Silicon nitride nanowire / calcium phosphate ceramic non-combustible paper and preparation method thereof

Abstract

The invention discloses a silicon nitride nanowire / calcium phosphate ceramic non-combustible paper and a preparation method thereof, comprising the following steps: 1) obtaining a solution A; 2) allowing the solution A to stand and solidify, and then grinding it into powder B; 3) evenly spreading the powder B obtained in the step 2) on a substrate, then placing it in a heating furnace for heat treatment, and after cooling with the furnace, peeling the obtained product from the surface of the substrate to obtain a sample C; 4) placing the sample C in a chemical vapor deposition furnace, heating it again, then introducing natural gas and argon, and keeping the temperature, to obtain a sample D; 5) obtaining a solution E; 6) using a graphite plate as an anode, the sample D as a cathode, and the solution E as an electrolyte to perform electrolytic deposition to obtain a sample F; 7) placing the sample F in an oxidation furnace, performing oxidation treatment in an air atmosphere, and cooling it to obtain the silicon nitride nanowire / calcium phosphate ceramic non-combustible paper. The non-combustible paper prepared by the method has excellent acid and alkali corrosion resistance and fire resistance, and has a heat insulation effect.

Description

Technical Field

[0001] The present invention relates to non-combustible paper and a preparation method thereof, and in particular to silicon nitride nanowire / calcium phosphate ceramic non-combustible paper and a preparation method thereof. Background Art

[0002] As one of the four great inventions of ancient my country, paper is of immense significance. As a carrier of text and a medium for disseminating information, its invention has played a crucial role in the inheritance of culture and the development of science and technology. Traditional paper, primarily made from plant fibers, suffers from its flammability and fire resistance, which can lead to the destruction of books and paper documents in fires. This is the primary cause of the destruction of numerous paper artifacts. Furthermore, traditional paper lacks acid and alkali corrosion resistance in harsh environments and lacks thermal insulation properties in high-temperature environments. Therefore, the development of a superior new type of paper that is both non-flammable, acid and alkali resistant, and heat-insulating holds great promise.

[0003] Document 1, “L.-Y. Dong, Y.-J. Zhu, A New Kind of Fireproof, Flexible, Inorganic, Nanocomposite Paper and Its Application to the Protection Layer in Flame-Retardant Fiber-Optic Cables, Chemistry–A European Journal, 23 (2017) 4597–4604,” reports a flame-retardant paper with excellent smoothness and gloss. The paper is composed of hydroxyapatite nanowires and glass fibers and can withstand burning in an alcohol lamp for 5 minutes.

[0004] Reference 2, "L.-Y. Dong, Y.-J. Zhu, Fire-Resistant Inorganic Analogous Xuan Paper with Thousands of Years' Super-Durability, ACS Sustainable Chemistry & Engineering, 6 (2018) 17239-17251," reports a super-durable flame-retardant inorganic Xuan-like paper. The paper is prepared by vacuum filtration of a mixed slurry consisting of hydroxyapatite nanowires, glass fibers, and an inorganic binder. The flame-retardant paper can withstand burning with an alcohol lamp for 10 minutes.

[0005] Reference 3, "L. Cheng, J. Feng, Flexible and fire-resistant all-inorganic composite film with high in-plane thermal conductivity, Chemical Engineering Journal, 398 (2020) 125633," reports a flexible fire-resistant paper made from hydroxyapatite nanowires and boron nitride nanosheets. The paper is prepared by vacuum filtration of a mixed slurry consisting of hydroxyapatite nanowires and a boron nitride dispersion. The resulting flame-retardant paper can withstand burning in an alcohol lamp for 5 minutes.

[0006] The fire-resistant paper prepared in the above-mentioned literature has two problems. First, the fire-resistant performance of the fire-resistant paper reported in the above-mentioned literature is limited, and can only withstand the burning of an alcohol lamp for 10 minutes at most. Second, the paper prepared in the literature only achieves fire resistance and lacks heat insulation and acid and alkali corrosion resistance. Summary of the Invention

[0007] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide a silicon nitride nanowire / calcium phosphate ceramic non-combustible paper and a preparation method thereof. The non-combustible paper prepared by this method has excellent acid and alkali corrosion resistance and fire resistance, and has a heat insulation effect.

[0008] To achieve the above object, the present invention discloses a method for preparing silicon nitride nanowire / calcium phosphate ceramic non-combustible paper, comprising the following steps:

[0009] 1) uniformly mixing polysilazane, ferrocene and xylene to obtain solution A;

[0010] 2) Allow solution A to solidify and then grind into powder B;

[0011] 3) Powder B obtained in step 2) is evenly spread on a substrate, and then placed in a heating furnace for heat treatment. After cooling in the furnace, the resulting product is peeled off from the substrate surface to obtain sample C;

[0012] 4) Place sample C in a chemical vapor deposition furnace, increase the temperature, then introduce natural gas and argon gas, and maintain the temperature to obtain sample D;

[0013] 5) uniformly mixing the calcium nitrate solution and the ammonium dihydrogen phosphate solution to obtain solution E;

[0014] 6) Using a graphite plate as the anode, sample D as the cathode, and solution E as the electrolyte, electrolytic deposition was performed to obtain sample F;

[0015] 7) Sample F is placed in an oxidation furnace and oxidized in an air atmosphere. After cooling, silicon nitride nanowire / calcium phosphate ceramic non-combustible paper is obtained.

[0016] In step 1), the mass ratio of polysilazane to ferrocene is (7-10):1.

[0017] In step 1), the volume ratio of xylene to polysilazane is (2-5):1.

[0018] The curing time in step 2) is 5-7 days.

[0019] The substrate is U-shaped graphite paper.

[0020] The process of heat treatment in step 3) is:

[0021] The substrate covered with powder B is placed in a high-temperature furnace for heat treatment for 2-4 hours, wherein the heat treatment temperature is 1350° C.-1550° C. and the nitrogen pressure is 0.10-0.30 MPa.

[0022] The specific operations of step 4) are:

[0023] Place sample C in a chemical vapor deposition furnace, raise the temperature to 1000°C-1100°C, then introduce natural gas at a flow rate of 0.6-1 L / min and argon at a flow rate of 2.2-2.6 L / min, and keep the temperature for 1-3 hours to obtain sample D;

[0024] In step 5), the concentration of the calcium nitrate solution is 30-90 mmol / L, and the concentration of the ammonium dihydrogen phosphate solution is 20-60 mmol / L, wherein the molar ratio of calcium nitrate to ammonium dihydrogen phosphate in solution E is 1-3.

[0025] In step 6), the temperature during the electrolytic deposition process is 40-60° C., the constant voltage is 3-5 V, and the time is 30-50 minutes.

[0026] In step 7), the temperature during the oxidation process is 500-800° C., and the oxidation time is 1-3 hours.

[0027] The invention discloses a silicon nitride nanowire / calcium phosphate ceramic non-combustible paper, which is prepared based on the preparation method of the silicon nitride nanowire / calcium phosphate ceramic non-combustible paper.

[0028] The present invention has the following beneficial effects:

[0029] The silicon nitride nanowire / calcium phosphate ceramic non-combustible paper and its preparation method described in the present invention are as follows: a layer of pyrolytic carbon intermediate is prepared on the silicon nitride nanowire film by chemical vapor deposition, calcium phosphate ceramic is then introduced by electrochemical deposition, and finally the pyrolytic carbon intermediate is removed by oxidation treatment to obtain the silicon nitride nanowire / calcium phosphate ceramic non-combustible paper. Among them, it should be noted that the present invention constructs a pyrolytic carbon intermediate, and the role of the pyrolytic carbon intermediate is to induce the growth of calcium phosphate ceramics and promote the effective combination of calcium phosphate ceramics and silicon nitride nanowires. Its working principle is: a) the pyrolytic carbon intermediate changes the surface morphology of the silicon nitride nanowires, and the morphology of the pyrolytic carbon intermediate induces the regular and orderly growth of calcium phosphate ceramics; b) the pyrolytic carbon intermediate improves the conductivity of the silicon nitride nanowires, thereby promoting the effective nucleation of calcium phosphate ceramics during electrochemical deposition and improving the interface bonding between calcium phosphate ceramics and silicon nitride nanowires; c) the pyrolytic carbon intermediate gives the silicon nitride nanowires a shaping effect, ensuring the dimensional stability of the silicon nitride nanowires in the electrolyte, thereby effectively achieving the uniform growth of calcium phosphate ceramics on the surface of the silicon nitride nanowires. The present invention successfully combines silicon nitride nanowires and calcium phosphate ceramics by constructing a pyrolytic carbon intermediate to prepare silicon nitride nanowire / calcium phosphate ceramic non-combustible paper. The non-combustible paper can be burned with an alcohol lamp for up to 72 hours without damage or dimensional change, and can be burned with a 1000°C spray gun for up to 15 minutes without damage or dimensional change. It can also be corroded in a 1 mol / L hydrochloric acid solution for up to 3 hours without damage or dimensional change, and in a 1 mol / L sodium hydroxide solution for up to 3 hours without damage or dimensional change. It can also achieve high-temperature thermal insulation, reducing the temperature of 650°C to a minimum of 240°C. Therefore, the non-combustible paper prepared by the present invention has excellent acid and alkali corrosion resistance, fire resistance, and thermal insulation effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is an optical photograph of the silicon nitride nanowire / calcium phosphate ceramic non-combustible paper prepared in Example 3;

[0031] Figure 2 This is a scanning electron microscope image of the silicon nitride nanowires / / calcium phosphate ceramic non-combustible paper prepared in Example 3;

[0032] Figure 3 This is an optical photograph of the silicon nitride nanowire / calcium phosphate ceramic non-combustible paper prepared in Example 3;

[0033] Figure 4a Optical photograph of the silicon nitride nanowire / calcium phosphate ceramic non-combustible paper prepared in Example 3 before testing;

[0034] Figure 4b for Figure 4a An optical photograph of the non-combustible paper shown in the figure undergoing a 72-hour fire resistance test under the flame of an alcohol lamp;

[0035] Figure 4c for Figure 4a An optical photograph of the non-combustible paper shown in FIG after a 72-hour fire resistance test under an alcohol burner flame;

[0036] Figure 4d This is an optical photograph of the silicon nitride nanowire / calcium phosphate ceramic non-combustible paper prepared in Example 3 before testing;

[0037] Figure 4e for Figure 4d Optical photograph of the non-combustible paper subjected to a 15-minute fire resistance test under a 1000°C torch flame;

[0038] Figure 4f for Figure 4d Optical photograph of the non-combustible paper after being subjected to a 15-minute fire resistance test under a 1000-degree Celsius torch flame;

[0039] Figure 5 This is a photo of the thermal insulation performance test of the silicon nitride nanowire / calcium phosphate ceramic non-combustible paper prepared in Example 3;

[0040] Figure 6 This is an optical photograph of the corrosion resistance test of the silicon nitride nanowire / calcium phosphate ceramic non-combustible paper prepared in Example 3;

[0041] Figure 7 This is an optical photograph of the thin film prepared in Example 6 that does not have a printable effect;

[0042] Figure 8 This is a scanning electron microscope photograph of the unsuccessful preparation of silicon nitride nanowire / calcium phosphate ceramic non-combustible paper in Example 6. DETAILED DESCRIPTION

[0043] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only embodiments of a part of the present invention, not all embodiments, and are not intended to limit the scope of the present invention. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessary confusion of the concepts disclosed in the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work should fall within the scope of protection of the present invention.

[0044] The accompanying drawings illustrate schematic diagrams of the structures of the disclosed embodiments of the present invention. These figures are not drawn to scale; for the purpose of clarity, some details are exaggerated and some details may be omitted. The shapes of the various regions and layers shown in the figures, as well as their relative sizes and positional relationships, are merely exemplary and may deviate in practice due to manufacturing tolerances or technical limitations. Those skilled in the art may design regions / layers with different shapes, sizes, and relative positions as needed.

[0045] The method for preparing the silicon nitride nanowire / calcium phosphate ceramic non-combustible paper of the present invention comprises the following steps:

[0046] 1) uniformly mixing polysilazane, ferrocene, and xylene to obtain solution A, wherein the mass ratio of polysilazane to ferrocene is (7-10):1, and the volume ratio of xylene to polysilazane is (2-5):1;

[0047] 2) Let solution A stand for 5-7 days to solidify, then grind into powder B;

[0048] 3) Powder B obtained in step 2) is evenly spread on a U-shaped graphite paper, and then heat-treated in a high-temperature furnace for 2-4 hours at a temperature of 1350° C. to 1550° C. and a nitrogen pressure of 0.10-0.30 MPa. After cooling in the furnace, the resulting product is peeled off the surface of the U-shaped graphite paper to obtain sample C;

[0049] 4) Place sample C in a chemical vapor deposition furnace, raise the temperature to 1000°C-1100°C, then introduce natural gas at a flow rate of 0.6-1 L / min and argon at a flow rate of 2.2-2.6 L / min, and maintain the temperature for 1-3 hours to obtain sample D;

[0050] 5) preparing a calcium nitrate solution having a concentration of 30-90 mmol / L, and then preparing an ammonium dihydrogen phosphate solution having a concentration of 20-60 mmol / L, uniformly mixing the calcium nitrate solution and the ammonium dihydrogen phosphate solution, and stirring to obtain a solution E, wherein the molar ratio of calcium nitrate to ammonium dihydrogen phosphate in solution E is 1-3;

[0051] 6) using a graphite plate as an anode, sample D as a cathode, and solution E as an electrolyte, depositing at a temperature of 40-60° C. and a constant voltage of 3-5 V for 30-50 minutes to obtain sample F;

[0052] 7) Place sample F in an oxidation furnace at 500-800° C. and perform oxidation treatment in an air atmosphere for 1-3 hours. After cooling, silicon nitride nanowire / calcium phosphate ceramic non-combustible paper is obtained.

[0053] The present invention successfully combines silicon nitride nanowires and calcium phosphate ceramics by constructing a pyrolytic carbon intermediate, producing a silicon nitride nanowire / calcium phosphate ceramic non-combustible paper. This paper can withstand burning in an alcohol lamp for up to 72 hours without damage or dimensional change, and in a 1000°C spray gun for up to 15 minutes without damage or dimensional change. It can also withstand corrosion in a 1 mol / L hydrochloric acid solution for up to 3 hours without damage or dimensional change, and in a 1 mol / L sodium hydroxide solution for up to 3 hours without damage or dimensional change. It also provides high-temperature insulation, reducing insulation from 650°C to a minimum of 240°C. Overall, the present invention successfully produces a multifunctional paper that is both non-combustible, corrosion-resistant, and heat-insulating.

[0054] Example 1

[0055] The specific operation process of this embodiment is as follows:

[0056] 1) uniformly mixing polysilazane, ferrocene, and xylene, wherein the mass ratio of polysilazane to ferrocene is 7:1, and the volume ratio of xylene to polysilazane is 2:1, and mixing uniformly to obtain solution A;

[0057] 2) Solution A was allowed to solidify for 5 days, then ground into powder B in a mortar;

[0058] 3) Powder B was evenly spread on a U-shaped graphite paper and then heat-treated in a high-temperature furnace at 1350°C and a nitrogen pressure of 0.10 MPa for 2 hours. After the furnace cooled, the product was peeled off the surface of the U-shaped graphite paper to obtain sample C;

[0059] 4) Place sample C in a chemical vapor deposition furnace, raise the temperature to 1000°C, introduce natural gas at a flow rate of 0.6 L / min, and simultaneously introduce argon at a flow rate of 2.2 L / min. Maintain the temperature for 1 hour to obtain sample D.

[0060] 5) preparing a 30 mmol / L calcium nitrate solution and then preparing a 20 mmol / L ammonium dihydrogen phosphate solution, uniformly mixing the calcium nitrate solution and the ammonium dihydrogen phosphate solution, wherein the molar ratio of calcium nitrate to ammonium dihydrogen phosphate is 1.5, and stirring to obtain a solution E;

[0061] 6) Using a graphite plate as the anode, sample D as the cathode, and solution E as the electrolyte, the deposition was carried out at a temperature of 40°C and a constant voltage of 3V for 30 minutes to obtain sample F;

[0062] 7) Sample F was placed in an oxidation furnace at 500 degrees Celsius and oxidized in an air atmosphere for 1 hour. After cooling, the sample was taken out to obtain silicon nitride nanowire / calcium phosphate ceramic non-combustible paper.

[0063] In Example 1, a silicon nitride nanowire / calcium phosphate ceramic non-combustible paper was successfully prepared. It survived 60 hours of burning with an alcohol lamp and 10 minutes of burning with a 1000°C spray gun. It also withstood corrosion in a 1 mol / L hydrochloric acid solution for 2 hours and a 1 mol / L sodium hydroxide solution for 2 hours. It also insulated a 650°C temperature to 310°C, with a temperature difference of 340°C between the front and back of the insulation paper, a 52% reduction in temperature.

[0064] Example 2

[0065] The specific operation process of this embodiment is as follows:

[0066] 1) uniformly mixing polysilazane, ferrocene, and xylene, wherein the mass ratio of polysilazane to ferrocene is 10:1, and the volume ratio of xylene to polysilazane is 5:1, and mixing uniformly to obtain solution A;

[0067] 2) Solution A was allowed to solidify for 7 days, then ground into powder B in a mortar;

[0068] 3) Powder B was evenly spread on a U-shaped graphite paper and then heat-treated in a high-temperature furnace at 1550°C and a nitrogen pressure of 0.30 MPa for 4 hours. After the furnace cooled, the product was peeled off the surface of the U-shaped graphite paper to obtain sample C;

[0069] 4) Place sample C in a chemical vapor deposition furnace, raise the temperature to 1100°C, introduce natural gas at a flow rate of 1 L / min, and simultaneously introduce argon at a flow rate of 2.6 L / min. Maintain the temperature for 3 hours to obtain sample D.

[0070] 5) preparing a 90 mmol / L calcium nitrate solution and a 60 mmol / L ammonium dihydrogen phosphate solution, uniformly mixing the calcium nitrate solution and the ammonium dihydrogen phosphate solution, and stirring to obtain a solution E, wherein the molar ratio of calcium nitrate to ammonium dihydrogen phosphate in solution E is 1.5;

[0071] 6) Using a graphite plate as the anode, sample D as the cathode, and solution E as the electrolyte, the deposition was carried out at a temperature of 60°C and a constant voltage of 5V for 50 minutes to obtain sample F;

[0072] 7) Sample F was placed in an oxidation furnace at 800° C. and oxidized in an air atmosphere for 3 hours. After cooling, the sample was taken out to obtain silicon nitride nanowire / calcium phosphate ceramic non-combustible paper.

[0073] In Example 2, silicon nitride nanowire / calcium phosphate ceramic non-combustible paper was successfully prepared. It was able to withstand 65 hours of burnt-in alcohol burner fire and 12 minutes of burnt-in 1000°C spray gun fire without damage. It was also able to withstand corrosion for 2.5 hours in a 1 mol / L hydrochloric acid solution and 2.5 hours in a 1 mol / L sodium hydroxide solution without damage. It was able to reduce a 650°C heat insulation temperature to 260°C, with a temperature difference of 390°C between the front and back of the insulation paper, a 60% temperature reduction.

[0074] Example 3

[0075] The specific operation process of this embodiment is as follows:

[0076] 1) uniformly mixing polysilazane, ferrocene, and xylene, wherein the mass ratio of polysilazane to ferrocene is 9:1, and the volume ratio of xylene to polysilazane is 4:1, and mixing uniformly to obtain solution A;

[0077] 2) Solution A was allowed to solidify for 6 days, then ground into powder B in a mortar;

[0078] 3) Powder B was evenly spread on a U-shaped graphite paper and then heat-treated in a high-temperature furnace at 1450°C and a nitrogen pressure of 0.20 MPa for 3 hours. After the furnace cooled, the product was peeled off the surface of the U-shaped graphite paper to obtain sample C;

[0079] 4) Place sample C in a chemical vapor deposition furnace, raise the temperature to 1070°C, introduce natural gas at a flow rate of 0.8 L / min, and simultaneously introduce argon at a flow rate of 2.4 L / min. Maintain the temperature for 2 hours to obtain sample D.

[0080] 5) preparing an 85 mmol / L calcium nitrate solution and a 50 mmol / L ammonium dihydrogen phosphate solution, uniformly mixing the calcium nitrate solution and the ammonium dihydrogen phosphate solution, and stirring to obtain a solution E, wherein the molar ratio of calcium nitrate to ammonium dihydrogen phosphate in solution E is 1.7;

[0081] 6) Using a graphite plate as the anode, sample D as the cathode, and solution E as the electrolyte, the deposition was carried out at a temperature of 50°C and a constant voltage of 4V for 40 minutes to obtain sample F;

[0082] 7) Sample F was placed in an oxidation furnace at 600° C. and oxidized in an air atmosphere for 2 hours. After cooling, the sample was taken out to obtain silicon nitride nanowire / calcium phosphate ceramic non-combustible paper.

[0083] refer to Figures 1 to 6In Example 3, silicon nitride nanowire / calcium phosphate ceramic non-combustible paper was successfully prepared. It was burned with an alcohol lamp for 72 hours without damage, and burned with a 1000°C spray gun for 15 minutes without damage. It was corroded in a 1 mol / L hydrochloric acid solution for 3 hours without damage, and in a 1 mol / L sodium hydroxide solution for 3 hours without damage. It was able to reduce a high temperature of 650°C to 240°C, with a temperature difference of 410°C between the front and back of the insulation paper, a 63% temperature reduction.

[0084] Example 4

[0085] The specific operation process of this embodiment is as follows:

[0086] 1) uniformly mixing polysilazane, ferrocene, and xylene, wherein the mass ratio of polysilazane to ferrocene is 8:1, and the volume ratio of xylene to polysilazane is 3:1, and mixing uniformly to obtain solution A;

[0087] 2) Solution A was allowed to solidify for 7 days, then ground into powder B in a mortar;

[0088] 3) Powder B was evenly spread on a U-shaped graphite paper and then heat-treated in a high-temperature furnace at 1400°C and a nitrogen pressure of 0.25 MPa for 2.5 hours. After the furnace cooled, the product was peeled off the surface of the U-shaped graphite paper to obtain sample C;

[0089] 4) Place sample C in a chemical vapor deposition furnace, raise the temperature to 1050°C, introduce natural gas at a flow rate of 0.7 L / min, and simultaneously introduce argon at a flow rate of 2.5 L / min. Maintain the temperature for 1.5 hours to obtain sample D.

[0090] 5) preparing a 70 mmol / L calcium nitrate solution and a 40 mmol / L ammonium dihydrogen phosphate solution, uniformly mixing the calcium nitrate solution and the ammonium dihydrogen phosphate solution, and stirring to obtain a solution E, wherein the molar ratio of calcium nitrate to ammonium dihydrogen phosphate in solution E is 1.75;

[0091] 6) Using a graphite plate as the anode, sample D as the cathode, and solution E as the electrolyte, deposition was carried out at a temperature of 55°C and a constant voltage of 4.5V for 45 minutes to obtain sample F;

[0092] 7) Sample F was placed in an oxidation furnace at 750° C. and oxidized in an air atmosphere for 1.5 hours. After cooling, the sample was taken out to obtain silicon nitride nanowire / calcium phosphate ceramic non-combustible paper.

[0093] In Example 4, silicon nitride nanowire / calcium phosphate ceramic non-combustible paper was successfully prepared. It was burned in an alcohol lamp for 65 hours without damage, and burned in a 1000°C spray gun for 13 minutes without damage. It was also corroded in a 1 mol / L hydrochloric acid solution for 2 hours without damage, and in a 1 mol / L sodium hydroxide solution for 2 hours without damage. It was also able to reduce a 650°C high temperature to 270°C, with a temperature difference of 380°C between the front and back of the insulation paper, a 58% temperature reduction.

[0094] Example 5

[0095] The specific operation process of this embodiment is as follows:

[0096] 1) uniformly mixing polysilazane, ferrocene, and xylene, wherein the mass ratio of polysilazane to ferrocene is 8.5:1, and the volume ratio of xylene to polysilazane is 3.5:1, and mixing uniformly to obtain solution A;

[0097] 2) Solution A was allowed to solidify for 7 days, then ground into powder B in a mortar;

[0098] 3) Powder B was evenly spread on a U-shaped graphite paper and then heat-treated in a high-temperature furnace at 1500°C and a nitrogen pressure of 0.15 MPa for 3.5 hours. After the furnace cooled, the product was peeled off the surface of the U-shaped graphite paper to obtain sample C;

[0099] 4) Place sample C in a chemical vapor deposition furnace, raise the temperature to 1040° C., introduce natural gas at a flow rate of 0.85 L / min, and simultaneously introduce argon at a flow rate of 2.45 L / min. Maintain the temperature for 1 to 3 hours to obtain sample D.

[0100] 5) preparing a 60 mmol / L calcium nitrate solution and a 30 mmol / L ammonium dihydrogen phosphate solution, uniformly mixing the calcium nitrate solution and the ammonium dihydrogen phosphate solution, and stirring to obtain a solution E, wherein the molar ratio of calcium nitrate to ammonium dihydrogen phosphate in solution E is 2;

[0101] 6) Using a graphite plate as the anode, sample D as the cathode, and solution E as the electrolyte, deposition was carried out at a temperature of 55°C and a constant voltage of 3.5V for 35 minutes to obtain sample F;

[0102] 7) Sample F was placed in an oxidation furnace at 550° C. and oxidized in an air atmosphere for 1.5 hours. After cooling, the sample was taken out to obtain silicon nitride nanowire / calcium phosphate ceramic non-combustible paper.

[0103] In Example 5, silicon nitride nanowire / calcium phosphate ceramic non-combustible paper was successfully produced. It was burned with an alcohol lamp for 70 hours without damage, and with a 1000°C spray gun for 9 minutes without damage. It was also corroded in a 1 mol / L hydrochloric acid solution for 1.5 hours without damage, and in a 1 mol / L sodium hydroxide solution for 1.5 hours without damage. It was also able to insulate a high temperature of 650°C to 340°C, with a temperature difference of 310°C between the front and back of the insulation paper, a 48% temperature reduction.

[0104] Example 6

[0105] The specific operation process of this embodiment is as follows:

[0106] 1) uniformly mixing polysilazane, ferrocene, and xylene, wherein the mass ratio of polysilazane to ferrocene is 9:1, and the volume ratio of xylene to polysilazane is 4:1, and mixing uniformly to obtain solution A;

[0107] 2) Solution A was allowed to solidify for 6 days, then ground into powder B in a mortar;

[0108] 3) Powder B was evenly spread on a U-shaped graphite paper and then heat-treated in a high-temperature furnace at 1450°C and a nitrogen pressure of 0.20 MPa for 3 hours. After the furnace cooled, the product was peeled off the surface of the U-shaped graphite paper to obtain sample C;

[0109] 4) preparing an 85 mmol / L calcium nitrate solution and a 50 mmol / L ammonium dihydrogen phosphate solution, uniformly mixing the calcium nitrate solution and the ammonium dihydrogen phosphate solution, and stirring to obtain a solution E, wherein the molar ratio of calcium nitrate to ammonium dihydrogen phosphate in solution E is 1.7;

[0110] 5) Using a graphite plate as the anode, sample D as the cathode, and solution E as the electrolyte, deposition was carried out at a temperature of 50°C and a constant voltage of 4V for 40 minutes to obtain a thin film, but no silicon nitride nanowire / calcium phosphate ceramic non-combustible paper was obtained.

[0111] Example 6 did not successfully prepare silicon nitride / calcium phosphate ceramic non-combustible paper. Only a thin film appeared, which did not have the printable function and could not be used as paper. The optical image of the obtained material was as follows: Figure 7 The reason for the failure of the preparation is that this embodiment did not fully follow the preparation process and lacked the step 4) deposition of the pyrolytic carbon intermediate proposed by the present invention, resulting in no calcium phosphate ceramics. As a result, the final material was only a thin film that could not be used flat and was prone to curling and wrinkling, making it unsuitable for use as printing paper. The micromorphology of the obtained material is shown in FIG. Figure 8 shown.

[0112] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered by the scope of protection of the claims of the present invention.

Claims

1. A method for preparing silicon nitride nanowire / calcium phosphate ceramic non-combustible paper, characterized in that: The following steps are involved: 1) uniformly mixing polysilazane, ferrocene and xylene to obtain solution A; 2) Allow solution A to solidify and then grind into powder B; 3) Powder B obtained in step 2) is evenly spread on a substrate, and then placed in a heating furnace for heat treatment. After cooling in the furnace, the resulting product is peeled off from the substrate surface to obtain sample C; 4) Place sample C in a chemical vapor deposition furnace, increase the temperature, then introduce natural gas and argon gas, and maintain the temperature to obtain sample D; 5) uniformly mixing the calcium nitrate solution and the ammonium dihydrogen phosphate solution to obtain solution E; 6) Using a graphite plate as the anode, sample D as the cathode, and solution E as the electrolyte, electrolytic deposition was performed to obtain sample F; 7) Placing sample F in an oxidation furnace for oxidation treatment in an air atmosphere, and cooling to obtain silicon nitride nanowire / calcium phosphate ceramic non-combustible paper; In step 1), the mass ratio of polysilazane to ferrocene is (7-10):1; In step 1), the volume ratio of xylene to polysilazane is (2-5):1; The process of heat treatment in step 3) is: The substrate covered with powder B is placed in a high-temperature furnace for heat treatment for 2-4 hours, wherein the heat treatment temperature is 1350°C-1550°C and the nitrogen pressure is 0.10-0.30 MPa; The specific operations of step 4) are: Place sample C in a chemical vapor deposition furnace, raise the temperature to 1000°C-1100°C, then introduce natural gas at a flow rate of 0.6-1 L / min and argon at a flow rate of 2.2-2.6 L / min, and keep the temperature for 1-3 hours to obtain sample D; In step 5), the concentration of the calcium nitrate solution is 30-90 mmol / L, and the concentration of the ammonium dihydrogen phosphate solution is 20-60 mmol / L, wherein the molar ratio of calcium nitrate to ammonium dihydrogen phosphate in solution E is 1-3; In step 7), the temperature during the oxidation process is 500-800° C., and the oxidation time is 1-3 hours.

2. The method for preparing silicon nitride nanowire / calcium phosphate ceramic non-combustible paper according to claim 1, characterized in that: The curing time in step 2) is 5-7 days.

3. The method for preparing silicon nitride nanowire / calcium phosphate ceramic non-combustible paper according to claim 1, characterized in that: The substrate is U-shaped graphite paper.

4. The method for preparing silicon nitride nanowire / calcium phosphate ceramic non-combustible paper according to claim 1, characterized in that: In step 6), the temperature during the electrolytic deposition process is 40-60° C., the constant voltage is 3-5 V, and the time is 30-50 minutes.

5. A silicon nitride nanowire / calcium phosphate ceramic non-combustible paper, characterized in that: The non-combustible paper is prepared based on the method for preparing the silicon nitride nanowire / calcium phosphate ceramic paper according to any one of claims 1 to 4.

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