Modified authigenic ZTA / Fe-based composite material and preparation method thereof

Abstract

The invention discloses a modified authigenic ZTA / Fe-based composite material and a preparation method thereof, and belongs to the technical field of ceramic metal-based composite materials. The preparation method comprises the following steps: adding EDTA-2Na into a solution prepared from ferrous sulfate, ammonia water and oxalic acid through a chemical precipitation method, fully stirring and mixing with a ZTA precursor prepared from aluminum ammonium sulfate, zirconium oxychloride, yttrium nitrate, polyethylene glycol and ammonium bicarbonate through chemical coprecipitation, carrying out liquid-liquid doping, and carrying out a reduction process to obtain reduced powder; and finally, carrying out pre-pressing molding and vacuum hot pressing sintering to obtain the in-situ synthesized ZTA reinforced iron-based composite material. The EDTA-2Na can reduce the adsorption of oxygen on the surface of the material, reduce the generation of iron oxide in the reduction and sintering process, and enhance the hardness, compactness and wear resistance of the material. The modified authigenic ZTA / Fe-based composite material has the advantages of good compatibility of a ZTA ceramic phase and an iron metal phase and good interface bonding and wettability, and effectively overcomes the defects of agglomeration, particle surface pollution, poor wettability of ZTA ceramic and a matrix and the like of a traditional additional ceramic particle reinforced iron-based composite material.

Description

Technical Field

[0001] The present invention relates to a modified in-situ ZTA / Fe-based composite material and a preparation method thereof, belonging to the technical field of ceramic-metal matrix composite materials. Background Art

[0002] Ceramic-reinforced metal matrix composite materials are one of the common high-wear-resistant composite materials. Due to their advantages such as high hardness, high toughness, and high wear resistance, they are widely used in grinding and crushing equipment in fields such as building materials and mines. Among them, zirconia toughened alumina (ZTA) ceramic particle-reinforced iron-based composite materials have the advantages of good wear resistance, low cost, and easy process control, and have become an important research direction of wear-resistant materials.

[0003] Traditional ZTA ceramic-reinforced iron-based composite materials are prepared by solid-solid mixing of ceramic particles and metal powders by adding millimeter-sized ceramic particles. During the service process of wear-resistant parts, the high-hardness ceramic particles mainly bear the wear (such as Chinese patent application CN202110763577.8, Chinese patent ZL201811619659.X, CN202011165621.7, and ZL201410610883.8, etc.). However, problems such as poor wetting between ZTA particles and steel and low interfacial bonding strength are likely to occur, so that the composite material is prone to particle breakage and shedding under the action of extrusion pressure, thus not meeting the use conditions of high-pressure abrasive wear equipment. At present, ceramic-metal matrix composite materials can be prepared by adding ceramic particles or in-situ self-generated ceramic phases, and the method of in-situ self-generation synthesis can effectively solve the problems of ceramic particle-reinforced iron-based composite materials added externally.

[0004] Chinese Invention Patent CN113862548B discloses a method for preparing an in-situ self-generated ZTA particle-reinforced steel-based honeycomb composite material. Aluminum nitrate nonahydrate, zirconium oxynitrate hydrate, etc. are used as raw materials to prepare a transparent sol; steel-based powder is added to the sol for liquid-solid doping, and after stirring until solidification, vacuum drying and reduction of the ZTA / steel mixed powder are carried out in sequence; the ZTA / steel mixed powder is filled into the honeycomb walls of a honeycomb mold, and the steel-based powder is filled into the honeycomb holes of the honeycomb mold. After pressing and sintering, an in-situ self-generated ZTA ceramic particle-reinforced steel-based honeycomb composite material can be obtained. This liquid-solid doping method still has the problem of uniform mixing of the steel-based powder and the sol, and the obtained mixed powder is also prone to a layered structure. Chinese Invention Patent CN114921708B discloses a method for preparing a self-generated ZTA ceramic-reinforced iron-based composite material. The iron precursor generated by the hydrothermal reaction of ferric chloride and sodium hydroxide solutions is fully stirred and mixed with the ZTA precursor generated by the hydrothermal reaction of aluminum nitrate, zirconium oxyhydroxide, sodium hydroxide, etc. for liquid-liquid doping, and then a self-generated ZTA ceramic-reinforced steel-based composite material is obtained through processes such as roasting, reduction, and vacuum sintering. This liquid-liquid doping method can significantly improve the mixing uniformity of ZTA and iron, and the process is easy to control. However, this patent mainly uses the hydrothermal synthesis method for preparation, which requires reaction under high temperature and high pressure, resulting in harsh reaction conditions, high requirements for equipment performance, and large investment costs, and is not suitable for large-scale industrial production. In addition, the iron matrix in the ZTA / Fe-based composite material prepared by this method is extremely easy to oxidize in the air to generate iron metal oxides, reducing the bonding degree between the metal phase and the ceramic phase, and thus affecting the hardness and density of the two phases. Summary of the Invention

[0005] In order to overcome the problems in the background art, the purpose of the present invention is to provide a modified self-generated ZTA / Fe-based composite material and a preparation method thereof.

[0006] To achieve the above purpose, the present invention is realized through the following technical solutions:

[0007] A preparation method of a modified self-generated ZTA / Fe-based composite material includes the following steps:

[0008] (1) Add an oxalic acid solution to a ferrous sulfate solution with a pH value adjusted to 8 - 8.5 by ammonia water to obtain a yellow precipitate of ferrous oxalate, and then add EDTA-2Na to obtain an Fe complex;

[0009] (2) Dissolve ammonium aluminum sulfate dodecahydrate, zirconium oxyhydroxide octahydrate, and yttrium nitrate hexahydrate in water to obtain a salt solution, then add the salt solution to a mixed aqueous solution of ammonium bicarbonate and polyethylene glycol, adjust the pH value of the mixed solution with ammonia water in a water bath, and then let the obtained liquid stand for aging to obtain a ZTA precursor solution;

[0010] (3) Add the Fe complex to the ZTA precursor solution, and then filter, wash, and dry the mixed solution to obtain a mixed powder.

[0011] (4) Calcinate the mixed powder prepared in step (3) in a reducing gas to obtain a ZTA / Fe mixed powder, and then pre-press the ZTA / Fe mixed powder and put it into a graphite mold for hot pressing and sintering to obtain an in-situ self-generated ZTA / Fe composite material.

[0012] Preferably, the molar ratio of ferrous sulfate to oxalic acid is 1:1.2 - 1.5, and the molar ratio of the used EDTA-2Na to ferrous sulfate is 1:0.8 - 0.9.

[0013] Preferably, the molar ratio of ammonium aluminum sulfate dodecahydrate, zirconium oxychloride octahydrate, and yttrium nitrate hexahydrate is 1:(0.14 - 0.2):(0.04 - 0.1).

[0014] Preferably, in step (2), the temperature of the water bath is 45°C, the pH value is 7.5 - 8.5, and the static aging time is 2 - 2.5 h.

[0015] Preferably, the molar ratio of ammonium bicarbonate to polyethylene glycol is 0.45 - 0.51:0.002 - 0.01, and the number average molecular weight Mn of polyethylene glycol = 2000 g / mol.

[0016] Preferably, the molar ratio of ammonium aluminum sulfate dodecahydrate to ammonium bicarbonate is 0.08 - 0.09:0.45 - 0.51.

[0017] Preferably, the molar ratio of Fe to ZTA in the ZTA / Fe mixed powder is (7 - 8.5):(1.5 - 3).

[0018] Preferably, the temperature for calcination in the reducing gas is 480 - 550°C, the time is 3 - 3.5 h, and the flow rate of the reducing gas is 18 - 25 mL / min.

[0019] Preferably, the sintering temperature is 950 - 1200°C, and the sintering time is 1 - 2 h.

[0020] The present invention also claims the modified in-situ self-generated ZTA / Fe-based composite material prepared by the preparation method of the modified in-situ self-generated ZTA / Fe-based composite material.

[0021] Advantages of the present invention:

[0022] (1) The present invention uses disodium ethylenediaminetetraacetate (EDTA-2Na) to strengthen the in-situ self-generated ZTA / Fe-based composite material, and combines EDTA-2Na and Fe 2+ and Fe 3+The Fe(EDTA) complex formed by the reaction and the ZTA precursor are used to obtain a mixed powder through a liquid-liquid doping method, and then a mixed powder of ZTA and Fe is obtained by reduction with gas H2. During this preparation process, EDTA-2Na reduces the adsorption of oxygen on the material surface, reduces the formation of iron oxides during reduction and sintering, and at the same time enhances the hardness, density and wear resistance of the in-situ self-generated ZTA / Fe-based composite material. In particular, it can increase the hardness of the matrix region to be equivalent to that of the composite region. And EDTA-2Na will decompose and volatilize at 200-450 °C without generating any residues in the composite material, so no impurities are generated during the preparation process. Compared with traditional steel wear-resistant materials, the ceramic phase and metal phase interface of the ZTA / Fe composite material prepared by this method are better combined, and the comprehensive performance has been greatly improved. The hardness of its composite region and matrix region has increased by 1.9 times and 2.2 times respectively, its density has increased from 96.47% to 99.82%, and its wear resistance has increased by 5.1 times.

[0023] (2) The powder size in the ZTA (zirconia toughened alumina) ceramic reinforced iron-based composite material prepared by the present invention belongs to nanoparticles, the sintering temperature is reduced and the sintering time is shortened, the experimental conditions of the sintering and forming step are reduced, and the production efficiency can be effectively improved. Description of the Drawings

[0024] Figure 1 It is the morphology diagram of the mixed powder of the ZTA precursor and Fe(EDTA) and the ZTA / Fe mixed powder prepared in Example 1; (a) is the morphology diagram of the mixed powder of the ZTA precursor and Fe(EDTA); (b) is the morphology diagram of the ZTA / Fe mixed powder.

[0025] Figure 2 It is the microstructure diagram of the in-situ self-generated ZTA / Fe composite material prepared in Example 1. Detailed Description of the Invention

[0026] The present invention will be further described in detail below with reference to specific embodiments, but the protection scope of the present invention is not limited thereto.

[0027] Example 1

[0028] A preparation method of a modified self-generated ZTA / Fe-based composite material includes the following steps:

[0029] (1) Dissolve oxalic acid dihydrate in deionized water and stir well to obtain an oxalic acid solution; then dissolve ferrous sulfate heptahydrate in deionized water, control the molar ratio of ferrous sulfate heptahydrate to oxalic acid dihydrate to be 1:1.2. After stirring well, add ammonia water to the ferrous sulfate solution to adjust the pH value of the solution to 8, and then dropwise add the oxalic acid solution into this solution. While maintaining the temperature of the reaction system at 45 °C, react fully for 2 h, and then control the molar ratio of EDTA-2Na to ferrous sulfate heptahydrate to be 1:0.9, and add EDTA-2Na to form Fe(EDTA) complex.

[0030] (2) Dissolve ammonium alum dodecahydrate, zirconium octahydrate hydroxide and yttrium nitrate hexahydrate in deionized water to obtain a salt solution, control the molar ratio of the three metal salts to be 1:0.14:0.04, and then drop the salt solution into a solution prepared by dissolving 36.3574 g of ammonium bicarbonate and 0.7481 g of polyethylene glycol (MW (molecular weight of each ethylene glycol unit) = 44.05 g / mol, number average molecular weight Mn = 2000 g / mol) in 250 ml of deionized water at a constant speed. Control the temperature of the reaction system at 45 °C in a constant temperature water bath, use ammonia water to adjust the pH value of the mixed solution to 7.5, and then let the obtained liquid stand and age for 2 h to obtain a ZTA precursor solution.

[0031] (3) Quickly drop the Fe(EDTA) complex obtained in step (1) into the ZTA precursor solution obtained in step (2) and mix well. Control the molar ratio of Fe to ZTA to be 7:3. Then, after filtering and washing the mixed solution, dry it at 85 °C for 12 h to obtain a mixed powder of ZTA precursor and Fe(EDTA). As Figure 1 (a) shown, micron-sized mixed powder with irregular shapes is obtained.

[0032] (4) Put the mixed powder prepared in step (3) into a tube furnace, control the temperature of the reduction furnace to be 550 °C, the hydrogen flow rate to be 25 mL / min, and the time to be 3.5 h to obtain a ZTA / Fe mixed powder by reduction. As Figure 1 (b) shown, it can be seen that by using this method, a micron-sized in-situ ZTA and Fe mixed powder can be obtained, the powder particle size is fine and the mixing is uniform, and the ceramic surface is pollution-free.

[0033] (5) Pre-press the mixed powder and put it into a graphite mold, and obtain an in-situ ZTA / Fe composite material by rapid hot pressing sintering (sintering temperature 950 °C, sintering time 1 h). Its microstructure diagram is as Figure 2 shown (the black area is ZTA, and the white area is the matrix). It can be seen that the ceramic particles in the composite material are evenly dispersed, the interface between the ceramic phase and the metal phase is well combined, and there are no obvious defects.

[0034] Traditional ceramic-reinforced iron-based composite materials rely on pre-adding ceramic particles to a metal matrix, mixing the ceramic powder and metal powder evenly through ball milling, and then forming the blanks using powder metallurgy or cast infiltration. Compared to the ZTA ceramic-reinforced iron-based composite material prepared by solid-solid mixing of added particles, the in-situ self-generated ZTA ceramic-reinforced iron-based composite material prepared in this embodiment has a 5.1-fold increase in wear resistance, and the hardness of the composite area and the matrix has increased by 1.8 times and 2.2 times, respectively, and the density has increased from 96.47% to 99.82%. The volume wear rate of the traditional ZTA ceramic-reinforced iron-based composite material prepared by solid-solid mixing of added particles is 290mm 3 / h, the hardness of the composite area and the matrix area are HV277.94 and HV219.53 respectively. The volume wear rate of the in-situ self-generated ZTA ceramic reinforced iron-based composite material prepared in this embodiment is 57mm 3 / h, the hardness of the composite area and the matrix area are HV500.29 and HV482.97 respectively, and the test method of volume wear rate is GB / T12444-2006.

[0035] Example 2

[0036] A method for preparing a modified self-generated ZTA / Fe-based composite material, the specific steps are as follows:

[0037] (1) Oxalic acid dihydrate is dissolved in deionized water and stirred thoroughly to obtain an oxalic acid solution; ferrous sulfate heptahydrate is then dissolved in deionized water, and the molar ratio of ferrous sulfate heptahydrate to oxalic acid dihydrate is controlled to be 1:1.3. After sufficient stirring, ammonia water is added dropwise to the solution to adjust the pH value of the solution to 8, and then the oxalic acid solution is added dropwise to the solution. After fully reacting for 2.5 hours while maintaining the temperature of the reaction system at 45° C., the molar ratio of the modifier to ferrous sulfate heptahydrate is controlled to be 1:0.9, and the modifier is added to generate an Fe(EDTA) complex.

[0038] (2) Ammonium aluminum sulfate dodecahydrate, zirconium oxychloride octahydrate and yttrium nitrate hexahydrate were dissolved in deionized water to obtain a salt solution, and the molar ratio of the three metal salts was controlled to be 1:0.16:0.06. The salt solution was then uniformly dripped into a solution prepared by dissolving ammonium bicarbonate and polyethylene glycol (MW (molecular weight of each ethylene glycol unit) = 44.05 g / mol, number average molecular weight Mn = 2000 g / mol) in deionized water. The temperature of the reaction system was controlled to be 45° C. in a constant temperature water bath, and the pH value of the mixed solution was adjusted to 8 with ammonia water. The resulting liquid was then aged for 2.5 hours to obtain a ZTA precursor solution.

[0039] (3) The Fe(EDTA) complex obtained in step (1) is quickly added dropwise to the ZTA precursor solution obtained in step (2) and mixed thoroughly to control the molar ratio of Fe to ZTA to be 7.5:2.5. The mixed solution is filtered and washed, and then dried at 85° C. for 13 h to obtain a mixed powder of ZTA precursor and Fe(EDTA).

[0040] (4) The mixed powder prepared in step (3) is placed in a tubular furnace, and the reduction furnace temperature is controlled to be 520° C., the hydrogen flow rate is 22 mL / min, and the time is 3.5 h to obtain a ZTA / Fe mixed powder.

[0041] (5) The mixed powder is pre-pressed and placed in a graphite mold and subjected to rapid hot pressing and sintering (sintering temperature 1000°C, sintering time 1.5 h) to obtain an in-situ self-generated ZTA / Fe composite material.

[0042] Compared with the ZTA ceramic reinforced iron-based composite material prepared by the traditional solid-solid mixing method with added particles, the wear resistance of the in-situ self-generated ZTA ceramic reinforced iron-based composite material prepared by the modified method of the present invention is improved by 5 times, the hardness of the composite area and the matrix area is increased by 1.7 times and 2.1 times respectively, and the density is increased from 96.47% to 99.80%. The volume wear rate of the ZTA ceramic reinforced iron-based composite material prepared by the traditional solid-solid mixing method with added particles is 290mm 3 / h, the hardness of the composite area and the matrix are HV277.94 and HV219.53 respectively; the volume wear rate of the in-situ self-generated ZTA ceramic reinforced iron-based composite material prepared in this embodiment is 58mm 3 / h, the hardness of the composite area and the matrix area are HV472.49 and HV461.01 respectively, and the test method of volume wear rate is GB / T 12444-2006.

[0043] Example 3

[0044] This embodiment relates to a chemical preparation method for strengthening a self-generated ZTA / Fe-based composite material by adding an external modifier, and the specific steps are as follows:

[0045] (1) Oxalic acid dihydrate is dissolved in deionized water and stirred thoroughly to obtain an oxalic acid solution; ferrous sulfate heptahydrate is dissolved in deionized water, and the molar ratio of ferrous sulfate heptahydrate to oxalic acid dihydrate is controlled to be 1:1.4; after sufficient stirring, ammonia water is added dropwise to the solution to adjust the pH value of the solution to 8.5; and then the oxalic acid solution is added dropwise to the solution; after sufficient reaction for 2 hours while maintaining the temperature of the reaction system at 45° C., the molar ratio of the modifier to ferrous sulfate heptahydrate is controlled to be 1:0.8, and the modifier is added to generate an Fe(EDTA) complex.

[0046] (2) Dissolve ammonium alum dodecahydrate, zirconium oxychloride octahydrate, and yttrium nitrate hexahydrate in deionized water to obtain a salt solution. Control the molar ratio of the three metal salts to be 1:0.18:0.08. Then, slowly drip the salt solution into the solution prepared by dissolving ammonium bicarbonate and polyethylene glycol (MW (molecular weight of each ethylene glycol unit) = 44.05 g / mol, number-average molecular weight Mn = 2000 g / mol) in deionized water. Control the temperature of the reaction system to be 45 °C in a constant-temperature water bath, and use ammonia water to adjust the pH value of the mixed solution to 8.5. Then, let the obtained liquid stand and age for 2 h to obtain a ZTA precursor solution.

[0047] (3) Directly and quickly drip the Fe(EDTA) complex obtained in step (1) into the ZTA precursor solution obtained in step (2) and mix well. Control the molar ratio of Fe to ZTA to be 8:2. Then, filter and wash the mixed solution, and dry it at 85 °C for 13 h to obtain a mixed powder of ZTA and Fe(EDTA).

[0048] (4) Put the mixed powder prepared in step (3) into a tube furnace, control the temperature of the reduction furnace to be 500 °C, the hydrogen flow rate to be 20 mL / min, and the time to be 3 h to obtain a ZTA / Fe mixed powder by reduction.

[0049] (5) Pre-press the mixed powder and put it into a graphite mold, and perform rapid hot pressing sintering (sintering temperature 1100 °C, sintering time 1.5 h) to obtain an in-situ self-generated ZTA / Fe composite material.

[0050] For the in-situ self-generated ZTA ceramic-reinforced iron-based composite material prepared by modification using the present invention, compared with the ZTA ceramic-reinforced iron-based composite material prepared by the traditional method of externally adding particles for solid-solid mixing, its wear resistance is increased by 5 times, the hardness of the composite zone and the matrix region are increased by 1.9 times and 2.2 times respectively, and the relative density is increased from 96.47% to 99.81%. The volume wear rate of the ZTA ceramic-reinforced iron-based composite material prepared by the traditional method of externally adding particles for solid-solid mixing is 290 mm 3 / h, and the hardness of the composite zone and the matrix region are HV277.94 and HV219.53 respectively; the volume wear rate of the in-situ self-generated ZTA ceramic-reinforced iron-based composite material prepared in this example is 58 mm 3 / h, and the hardness of the composite zone and the matrix region are HV528.09 and HV482.97 respectively. The test method for the volume wear rate is GB / T 12444-2006.

[0051] Example 4

[0052] This example relates to a chemical preparation method for an externally added modifier to strengthen the in-situ self-generated ZTA / Fe-based composite material. The specific steps are as follows:

[0053] (1) Dissolve oxalic acid dihydrate in deionized water and stir well to obtain an oxalic acid solution; then dissolve ferrous sulfate heptahydrate in deionized water, control the molar ratio of ferrous sulfate heptahydrate to oxalic acid dihydrate to be 1:1.5. After sufficient stirring, add ammonia water to this solution to adjust the pH value of the solution to 8.5, and then dropwise add the oxalic acid solution into this solution. While maintaining the temperature of the reaction system at 45 °C, react fully for 2.5 h, and then control the molar ratio of the modifier to ferrous sulfate heptahydrate to be 1:0.9, and add the modifier to generate Fe(EDTA) complex.

[0054] (2) Dissolve ammonium aluminum sulfate dodecahydrate, zirconium octahydrate hydroxide and yttrium nitrate hexahydrate in deionized water to obtain a salt solution, control the molar ratio of the three metal salts to be 1:0.2:0.1, and then drop the salt solution uniformly into the solution prepared by dissolving ammonium bicarbonate and polyethylene glycol (MW (molecular weight of each ethylene glycol unit) = 44.05 g / mol, number average molecular weight Mn = 2000 g / mol) in deionized water. In a constant temperature water bath, control the temperature of the reaction system to be 45 °C, use ammonia water to adjust the pH value of the mixed solution to 8, and then let the obtained liquid stand and age for 2 h to obtain a ZTA precursor solution.

[0055] (3) Quickly drop the Fe(EDTA) complex obtained in step (1) into the ZTA precursor solution obtained in step (2) and mix well, control the molar ratio of Fe to ZTA to be 8.5:1.5, and then filter and wash the mixed solution. After drying at 85 °C for 14 h, a mixed powder of ZTA precursor and Fe(EDTA) is obtained.

[0056] (4) Put the mixed powder prepared in step (3) into a tubular furnace, control the temperature of the reduction furnace to be 480 °C, the hydrogen flow rate to be 18 mL / min, and the time to be 3 h to obtain a ZTA / Fe mixed powder by reduction.

[0057] (5) Pre-press the mixed powder and put it into a graphite mold, and perform rapid hot pressing sintering (sintering temperature 1200 °C, sintering time 1.5 h) to obtain an in-situ self-generated ZTA / Fe composite material.

[0058] The in-situ self-generated ZTA ceramic reinforced iron-based composite material prepared by the present invention, compared with the ZTA ceramic reinforced iron-based composite material prepared by the traditional external particle solid-solid mixing method, has its wear resistance increased by 5.1 times, the hardness of the composite zone and the matrix region increased by 1.9 times and 2.3 times respectively, and the relative density increased from 96.47% to 99.82%. The volume wear rate of the ZTA ceramic reinforced iron-based composite material prepared by the traditional external particle solid-solid mixing method is 290 mm 3 / h, the hardness of the composite area and the matrix area are HV277.94 and HV219.53 respectively; the volume wear rate of the in-situ self-generated ZTA ceramic reinforced iron-based composite material prepared in this embodiment is 56mm 3 / h, the hardness of the composite area and the matrix area are HV528.09 and HV504.92 respectively, and the test method of volume wear rate is GB / T 12444-2006.

[0059] Comparative Example 1

[0060] A method for preparing a self-generated ZTA / Fe-based composite material comprises the following steps:

[0061] (1) Oxalic acid dihydrate is dissolved in deionized water and stirred thoroughly to obtain an oxalic acid solution; ferrous sulfate heptahydrate is then dissolved in deionized water, and the molar ratio of ferrous sulfate heptahydrate to oxalic acid dihydrate is controlled to be 1:1.2. After sufficient stirring, ammonia water is added dropwise to the ferrous sulfate solution to adjust the pH value of the solution to 8, and then the oxalic acid solution is added dropwise to the solution. The reaction is continued for 2 hours while the temperature of the reaction system is maintained at 45°C to generate an Fe precursor.

[0062] (2) Ammonium aluminum sulfate dodecahydrate, zirconium oxychloride octahydrate and yttrium nitrate hexahydrate were dissolved in deionized water to obtain a salt solution, and the molar ratio of the three metal salts was controlled to be 1:0.14:0.04. The salt solution was then uniformly dripped into a solution prepared by dissolving 36.3571 g of ammonium bicarbonate and 7.7816 g of polyethylene glycol (MW (molecular weight of each ethylene glycol unit) = 44.05 g / mol, number average molecular weight Mn = 2000 g / mol) in 250 ml of deionized water. The temperature of the reaction system was controlled to be 45° C. in a constant temperature water bath, and the pH value of the mixed solution was adjusted to 7.5 with aqueous ammonia. The resulting liquid was then allowed to stand and age for 2 h to obtain a ZTA precursor solution.

[0063] (3) The Fe precursor obtained in step (1) is quickly added dropwise to the ZTA precursor solution obtained in step (2) and mixed thoroughly to control the molar ratio of Fe to ZTA to be 7:3. The mixed solution is then filtered and washed, and dried at 85° C. for 12 h to obtain a mixed powder of ZTA precursor and Fe.

[0064] (4) The mixed powder prepared in step (3) is placed in a tubular furnace, and the reduction furnace temperature is controlled to be 550° C., the hydrogen flow rate is 25 mL / min, and the time is 3.5 h to obtain a ZTA / Fe mixed powder.

[0065] (5) The mixed powder is pre-pressed and placed in a graphite mold and subjected to rapid hot pressing and sintering (sintering temperature 950°C, sintering time 1 h) to obtain an in-situ self-generated ZTA / Fe composite material.

[0066] The hardness of the in-situ self-generated ZTA / Fe composite material prepared in this comparative example in the composite area and the matrix area is HV409.52 and HV300.28 respectively, the volume wear rate is 77 mm 3 / h, and the relative density is 99.35%.

[0067] Comparative Example 2

[0068] A preparation method of a modified self-generated ZTA / Fe-based composite material includes the following steps:

[0069] (1) Take oxalic acid dihydrate and dissolve it in deionized water and stir well to obtain an oxalic acid solution; then dissolve ferrous sulfate heptahydrate in deionized water, control the molar ratio of ferrous sulfate heptahydrate to oxalic acid dihydrate to be 1:1.2, after stirring well, add ammonia water to the ferrous sulfate solution to adjust the pH value of the solution to 8, and then dropwise add the oxalic acid solution into this solution drop by drop. While maintaining the temperature of the reaction system at 45 °C, after reacting fully for 2 h, control the molar ratio of EDTA to ferrous sulfate heptahydrate to be 1:0.9, and add EDTA to generate Fe(EDTA) complex.

[0070] (2) Dissolve ammonium aluminum sulfate dodecahydrate, zirconium oxychloride octahydrate and yttrium nitrate hexahydrate in deionized water to obtain a salt solution, control the molar ratio of the three metal salts to be 1:0.14:0.04, and then drop the salt solution evenly into the solution prepared by dissolving 36.3571 g of ammonium bicarbonate and 0.7281 g of polyethylene glycol in 250 ml of deionized water. Control the temperature of the reaction system at 45 °C in a constant temperature water bath, use ammonia water to adjust the pH value of the mixed solution to 7.5, and then let the obtained liquid stand for aging for 2 h to obtain a ZTA precursor solution.

[0071] (3) Quickly drop the Fe(EDTA) complex obtained in step (1) into the ZTA precursor solution obtained in step (2) and mix well. Control the molar ratio of Fe to ZTA to be 7:3. After filtering and washing the mixed solution, dry it at 85 °C for 12 h to obtain a mixed powder of ZTA precursor and Fe(EDTA).

[0072] (4) Put the mixed powder prepared in step (3) into a tubular furnace, control the temperature of the reduction furnace to be 550 °C, the hydrogen flow rate to be 25 mL / min, and the time to be 3.5 h to reduce and obtain a ZTA / Fe mixed powder.

[0073] (5) Pre-press the mixed powder and then put it into a graphite mold and perform rapid hot pressing sintering (sintering temperature 950 °C, sintering time 1 h) to obtain an in-situ self-generated ZTA / Fe composite material.

[0074] The hardness of the in-situ self-generated ZTA / Fe composite material prepared in this comparative example in the composite region and the matrix region is HV418.19 and HV306.81 respectively, the volume wear rate is 76 mm 3 / h, and the relative density is 99.31%.

[0075] Comparative Example 3

[0076] A preparation method of a modified self-generated ZTA / Fe-based composite material includes the following steps:

[0077] (1) Dissolve ferrous sulfate heptahydrate in deionized water. After sufficient stirring, add ammonia water to the ferrous sulfate solution to adjust the pH value of the solution to 8. Then, while maintaining the temperature of the reaction system at 45°C, react fully for 2 h. Then, control the molar ratio of EDTA-2Na to ferrous sulfate heptahydrate to be 1:0.9, and add EDTA-2Na to generate Fe(EDTA) complex.

[0078] (2) Dissolve ammonium aluminum sulfate dodecahydrate, zirconium oxychloride octahydrate, and yttrium nitrate hexahydrate in deionized water to obtain a salt solution. Control the molar ratio of the three metal salts to be 1:0.14:0.04. Then, slowly drip the salt solution into the solution prepared by dissolving 36.3599 g of ammonium bicarbonate and 0.7282 g of polyethylene glycol in 250 ml of deionized water. Control the temperature of the reaction system at 45°C in a constant temperature water bath, use ammonia water to adjust the pH value of the mixed solution to 7.5, and then let the obtained liquid stand and age for 2 h to obtain a ZTA precursor solution.

[0079] (3) Quickly drip the Fe(EDTA) complex obtained in step (1) into the ZTA precursor solution obtained in step (2) and mix well. Control the molar ratio of Fe to ZTA to be 7:3. Then, after filtering and washing the mixed solution, dry it at 85°C for 12 h to obtain a mixed powder of ZTA precursor and Fe(EDTA).

[0080] (4) Put the mixed powder prepared in step (3) into a tubular furnace, control the temperature of the reduction furnace at 550°C, the hydrogen flow rate at 25 mL / min, and the time at 3.5 h to reduce and obtain a ZTA / Fe mixed powder.

[0081] (5) Pre-press the mixed powder and then put it into a graphite mold for rapid hot pressing sintering (sintering temperature 950°C, sintering time 1 h) to obtain an in-situ self-generated ZTA / Fe composite material.

[0082] The hardness of the in-situ self-generated ZTA / Fe composite material prepared in this comparative example in the composite region and the matrix region is HV504.71 and HV426.19 respectively, the volume wear rate is 60 mm 3 / h, and the relative density is 99.63%.

[0083] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention rather than to limit them. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made to it in terms of form and details without departing from the scope defined by the claims of the present invention.

Claims

1. A preparation method of a modified in-situ ZTA / Fe-based composite material, characterized in that: It includes the following steps: (1) Add an oxalic acid solution to a ferrous sulfate solution with the pH adjusted to 8 - 8.5 by ammonia water, and then add EDTA-2Na to obtain an Fe complex; (2) Dissolve ammonium alum dodecahydrate, zirconium oxychloride octahydrate, and yttrium nitrate hexahydrate in water to obtain a salt solution. Then add the salt solution to an aqueous solution mixture of ammonium bicarbonate and polyethylene glycol, adjust the pH value of the mixture with ammonia water in a water bath, and then let the resulting liquid stand for aging to obtain a ZTA precursor solution; (3) Add the Fe complex to the ZTA precursor solution, and then filter, wash, and dry the mixed solution to obtain a mixed powder; (4) Calcinate the mixed powder prepared in step (3) in a reducing gas to obtain a ZTA / Fe mixed powder, and then pre-press the ZTA / Fe mixed powder and place it in a graphite mold for hot pressing sintering to obtain an in-situ self-generated ZTA / Fe composite material.

2. The preparation method of the modified in-situ ZTA / Fe-based composite material according to claim 1, characterized in that: The molar ratio of ferrous sulfate to oxalic acid is 1:1.2 - 1.5, and the molar ratio of the used EDTA-2Na to ferrous sulfate is 1:0.8 - 0.

9.

3. The preparation method of the modified in-situ ZTA / Fe-based composite material according to claim 1, wherein: The molar ratio of ammonium alum dodecahydrate, zirconium oxychloride octahydrate, and yttrium nitrate hexahydrate is 1:(0.14 - 0.2):(0.04 - 0.1).

4. The preparation method of the modified in-situ ZTA / Fe-based composite material according to claim 3, characterized in that: In step (2), the temperature of the water bath is 40 - 55°C, the pH value is 7.5 - 8.5, and the standing aging time is 2 - 2.5 h.

5. The preparation method of the modified in-situ ZTA / Fe-based composite material according to claim 1, wherein: The molar ratio of ammonium bicarbonate to polyethylene glycol is 0.45 - 0.51:0.008 - 0.01, and the number average molecular weight Mn of polyethylene glycol is 2000 g / mol.

6. The preparation method of the modified in-situ ZTA / Fe-based composite material according to claim 1, characterized in that: The molar ratio of ammonium alum dodecahydrate to ammonium bicarbonate is 0.08 - 0.09:0.45 - 0.

51.

7. The preparation method of the modified in-situ ZTA / Fe-based composite material according to claim 1, characterized in that: The molar ratio of Fe to ZTA in the ZTA / Fe mixed powder is (7 - 8.5):(1.5 - 3).

8. The preparation method of the modified in-situ ZTA / Fe-based composite material according to claim 1, wherein: The temperature of calcination in the reducing gas is 480 - 550°C, the time is 3 - 3.5 h, and the flow rate of the reducing gas is 18 - 25 mL / min.

9. The preparation method of the modified in-situ ZTA / Fe-based composite material according to claim 1, characterized in that: The sintering temperature is 950 - 1200°C, and the sintering time is 1 - 2 h.

10. A modified in-situ self-generated ZTA / Fe-based composite material prepared by the preparation method of the modified in-situ self-generated ZTA / Fe-based composite material according to any one of claims 1 - 9.

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