Zirconium carbide, as an ultra-high temperature ceramic material, has excellent physical and chemical properties, such as high hardness, high melting point, high wear resistance, low vapor pressure, low resistivity, good chemical stability and thermal stability. At present, The method of preparation of zirconium carbide is mainly with zirconium dioxide reaction with carbon reduction synthesis (J.M ater. Sci., 2004,39,6057-6066.), sol-gel (j. ur. Ceram. Soc., 2007,27,2061-2067.) and chemical vapor deposition (Appl. Surf. Sci., 2015332591-598, Surf. Coat. Technol., 2008203,87-90.) method. Industrial preparation of zirconia carbide is mainly by carbothermal reduction of zirconia dioxide (ZrO2). However, the preparation of zirconia carbide material by carbothermal reduction of zirconia requires a higher reaction temperature, the reaction temperature is about 1500 degrees Celsius, the reaction time is longer and the samples obtained are easy to agglomerate, and the dispersion is poor. Therefore, people are looking for a method to prepare zirconium carbide nanomaterials with cheap raw materials and simple process at low temperature. Technical realization elements: The invention mainly provides a method for preparing zirconium carbide nanomaterial by using waste plastics as carbon source, which has a wide and cheap raw material source, realizes the conversion of waste plastics to zirconium carbide nanomaterial by one-step chemical reaction, and solves the problem of environmental pollution caused by waste plastics. The technical scheme is as follows: A method for preparing zirconium carbide nanomaterials from waste plastics includes the following steps: (1) placing zirconium dioxide, waste plastics and lithium metal in a reactor with a mass ratio of 1:0.2 to 1:2-10; (2) Heating the reactor for chemical reaction, and cooling after the reaction; (3) The products were washed and dried to obtain zirconium carbide nanomaterials. Preferably, the waste plastic is selected from one or several of the waste polytetrafluoroethylene, polyvinyl chloride and polyethylene. Preferred, the temperature of chemical reaction in step (2) is 700-1000℃, and the reaction time is 5-50h. Preferably, dilute hydrochloric acid, distilled water and anhydrous ethanol are used in Step (3) to wash the product. Preferably, the reactor is a stainless steel autoclave. The reaction principle of the technical solution is as follows: ZrO2+1/n[CH2]n+4Li = ZrC+2Li2O+H2(1) 4ZrC+8Li2O+2LiCl3+H2(2)ZrO2+1/n[CF2] N6 +Li = ZrC+2Li2O+2LiF(3) The invention has the following advantages: The invention using plastic waste as carbon source, by one step reaction preparation of zirconium carbide nanometer materials, production process production equipment needed for this method is simple, the operation is simple, easy to realize industrialized production, the low temperature reaction need, the size of zirconium carbide related to reaction temperature, raw material sources and cheap, One-step chemical reaction to convert waste plastic to zirconium carbide nanomaterials. The invention not only provides a method for preparing zirconium carbide at low temperature, but also solves the environmental problems caused by waste plastics. Fig. 1 is the X-ray powder diffraction spectrum of the zirconium carbide nanomaterial prepared by Example 1; Fig. 2 is the transmission electron microscope image (a) and high resolution electron microscope image (b) of the zirconium carbide nanomaterial prepared in Example 1; Fig. 3 is the X-ray powder diffraction spectrum of zirconium carbide nanomaterials prepared in Example 2; Fig. 4 is a transmission electron microscope photograph of the zirconium carbide nanomaterial prepared in Example 2; Fig. 5 is the X-ray powder diffraction spectrum of zirconium carbide nanomaterials prepared in Example 3; Fig. 6 is a transmission electron microscope image of the zirconium carbide nanomaterial prepared in Example 3. Specific implementation methods The experimental methods in the following embodiments are all conventional methods unless there are special provisions. The experimental reagents and materials involved are all conventional biochemical reagents and materials unless there are special provisions. In Example 1, 0.60g of zirconia, 0.13g of waste polyethylene and 1.20g of lithium metal were added to a 20ml stainless steel autoclave, sealed and placed in an electric furnace capable of programmed heating. The furnace temperature rose from room temperature to 700℃ within 68 minutes, and then cooled naturally to room temperature after maintained at 700℃ for 10 hours. The final products in the autoclave include black deposits and residual gases. The black sediments stuck on the inner surface of the kettle wall were collected and washed with distilled water, dilute hydrochloric acid and anhydrous ethanol for several times. After filtration, the samples were obtained. The samples were dried in a vacuum drying oven at 50℃ for 4 hours respectively, and finally collected for characterization. The phase analysis of the powders was carried out by Japanese Rigakud/Max-γ A X-ray powder diffraction (XRD) apparatus, Cu graphite monochromator, tube pressure and current were 40kV and 40mA, respectively, and scanning speed was 10.0 degrees per minute. Fig. 1 shows the X-ray diffraction spectrum of the prepared product. As can be seen from Fig. 1, all the diffraction peaks in the X-ray diffraction spectrum (2θ at 10-80o) have high diffraction intensity and sharp peaks. All the diffraction peaks in the figure can be labeled as cubic phase zirconium carbide (ZRC), and the calculated lattice parameters are in good agreement with the reported data (JCPDSNo.65-0973,). No ZrO2, Zr and other impurity peaks were detected in XRD patterns, indicating that pure zirconium carbide was obtained by using waste polyethylene as carbon source. The morphology and structure of sample 1 were studied by transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM). Fig. 2A is a transmission electron microscope photo of the obtained zirconium carbide sample. It can be seen from Fig. 2A that the zirconium carbide sample is composed of nanoparticles with a size of 20 nm. Fig. 2b is a high-resolution transmission electron microscope photo of the obtained zirconium carbide sample. From Fig. 2b, clear lattice fringes can be seen, with a distance of 0.27 nm adjacent fringes corresponding to the (111) crystal plane spacing of zirconium carbide, which proves that the prepared zirconium carbide nanoparticles have good crystallinity. In Example 2, 0.60g of zirconia, 0.35g of waste polyvinyl chloride and 1.20g of lithium metal were added to a 20ml stainless steel autoclave, sealed and placed in an electric furnace capable of programmed heating. The furnace temperature rose from room temperature to 700℃ in 68 minutes, and then cooled naturally to room temperature after being maintained at 700℃ for 10 hours. The final products in the autoclave include black deposits and residual gases. The black sediments stuck on the inner surface of the kettle wall were collected and washed with distilled water, dilute hydrochloric acid and anhydrous ethanol for several times. After filtration, the samples were obtained. The samples were dried in a vacuum drying oven at 50℃ for 4 hours respectively, and finally collected for characterization. Fig. 3 shows the X-ray diffraction spectrum of the prepared zirconium carbide sample. All the diffraction peaks in the spectrum correspond to the five diffraction peaks of zirconium carbide, which proves that the prepared sample is cubic phase zirconium carbide material. Fig. 4 is a transmission electron microscopy (TEM) image of the prepared zirconium carbide sample. It can be seen from Figure 4 that the zirconium carbide sample prepared by waste PVC is also composed of nanoparticles. The average size of zirconium carbide nanoparticles is about 20 nanometers. In Example 3, 0.60g of zirconia, 0.30g of waste polytetrafluoroethylene and 1.20g of lithium metal were added to a 20ml stainless steel autoclave, sealed and placed in an electric furnace capable of programmed heating. The furnace temperature rose from room temperature to 700℃ within 60 minutes, and then cooled naturally to room temperature after being maintained at 700℃ for 40 hours. The final product in the autoclave consists of black deposits. The black sediments stuck on the inner surface of the kettle wall were collected and washed with distilled water, dilute hydrochloric acid and anhydrous ethanol for several times. After filtration, the samples were obtained. The samples were dried in a vacuum drying oven at 50℃ for 4 hours respectively, and finally collected for characterization. Fig. 5 is the typical X-ray powder diffraction spectrum of preparing zirconium carbide samples. According to the XRD pattern shown in Fig. 5, all the five diffraction peaks can be converted to the five diffraction peaks of cubic phase zirconium carbide, proving that zirconium carbide can also be prepared through the above embodiments using PTFE as a carbon source. Fig. 6 shows the transmission electron microscope (TEM) image of the obtained zirconium carbide sample. It can be seen from Fig. 6 that the zirconium carbide sample is composed of nanoparticles with an average particle size of about 30nm. The experimental conditions and structural information of zirconium carbide obtained in Embodiments 4-9 are shown in the table below. Table 1 The experimental conditions and product conditions for the preparation of zirconium carbide nanomaterials in each embodiment embodiment 4 embodiment 5 embodiment 6 embodiment 7 embodiment 8 embodiment 9 zirconium dioxide (g) 0.600.600.600.600.60Waste polyvinyl chloride (PVC,g)00.5000.200.200 Waste polytetrafluoroethylene (PTFE,g)0 Waste polyethylene (PE,g)0.30000.1000.20 Lithium Metal (g)1.202.406.001.202.406.00 Reaction temperature 800℃700℃ 700℃900℃1000℃ Reaction time 5H20H30H40H5H10H product Zirconium carbide, zirconium carbide zirconium carbide, zirconium carbide zirconium carbide, zirconium carbide production rate 70% 75% 80% 70% 70% 85% technologists, this area according to the technical solution of the above description and idea, to make other changes as well as the deformation, and all these changes as well as the deformation should fall within the scope of the present invention claims to protect.
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