A method for preparing potassium titanate powder

Abstract

The invention discloses a preparation method of potassium titanate powder, belonging to the technical field of inorganic materials. Titanium oxide or hydroxide and potassium compound are used as reaction raw materials, a soluble potassium source is completely dissolved and then added into a titanium precursor, and then the potassium source is recrystallized on the surface of the titanium precursor by a non-destructive spray granulation method to obtain potassium titanate precursor particles with uniform titanium and potassium components, and the size of the potassium titanate precursor particles can be adjusted as required; and potassium titanate powders with different microscopic morphologies and high crystallinity are prepared by controlling different calcination temperatures, heat preservation times, and impact forces and shear forces of grinding and crushing; and a dispersant is added in the preparation process to improve the dispersion degree of the titanium source, and an intercalation agent and a surfactant are added to adjust the microscopic morphology of the potassium titanate powder.

Description

Technical Field

[0001] The invention belongs to the technical field of inorganic materials and specifically discloses a method for preparing potassium titanate powder. Background Art

[0002] Potassium titanate is widely used in polymers, metals, ceramics, etc. It can greatly improve the high temperature resistance, wear resistance, weather resistance and mechanical properties of related composite materials. Potassium titanate is usually expressed as K2O•nTiO2 (n=1, 2, 4, 6, 8) to represent its composition, among which n=4 or 6 (i.e. potassium tetratitanate and potassium hexatitanate) has the greatest practical value.

[0003] The chemical formula of potassium hexatitanate is K2Ti6O 13 It is an inorganic compound with the appearance of gray-yellow powder. Potassium hexatitanate has the characteristics of stable chemical properties, excellent mechanical properties, corrosion resistance, heat insulation, wear resistance, low hardness at high temperature, etc. It has been widely used in petrochemical, automobile, electronic appliances, construction, machinery, environmental catalysis, sewage treatment, energy conversion, aerospace and other fields.

[0004] According to different morphologies, potassium hexatitanate is divided into whisker-shaped potassium hexatitanate, tunnel-shaped potassium hexatitanate, plate-shaped potassium hexatitanate, etc. Potassium hexatitanate with different morphologies has certain differences in performance, characteristics, and applications: for example, columnar potassium hexatitanate has the characteristics of large specific surface area and regular shape; plate-shaped potassium hexatitanate has better performance in strength and modulus; whisker-shaped potassium hexatitanate has good lubricity, extremely high infrared reflection and diffuse reflectivity, etc. Whisker-shaped potassium hexatitanate is potassium hexatitanate whisker, which is a new type of needle-shaped short fiber composite. When the whisker crystallizes, the atomic structure is highly ordered. This characteristic makes the whisker extremely strong, far exceeding various reinforcing agents.

[0005] Existing methods for preparing potassium titanate include a solvent method, a hydrothermal method, a melting method, a microwave synthesis method, a sol-gel method, a sintering method, etc., but they generally have limitations: for example, the melting method is to melt the raw materials and cool them to cultivate crystals, which has a low yield and a high reaction temperature; the hydrothermal method is to react the raw materials in hot water under high pressure conditions to generate crystals, and longer fibers can be obtained. However, this method requires high temperature and high pressure, and has high production costs and is very dangerous; the solvent method is a method in which the raw materials are reacted in a solvent (the solvents currently used are KCl, KF, KMnO4, K2WO4, etc.). This method has a high yield and the prepared potassium titanate single crystal fiber has good crystallinity. However, the use of solvents causes the material to corrode the sagger during high-temperature sintering, resulting in the sagger being unable to be reused, increasing the production cost, and the presence of fluoride ions can cause environmental pollution, and the presence of manganese and tungsten can affect product quality; the sintering method usually involves sintering the raw material mixture for a certain time and at a certain temperature. If this method does not have suitable process conditions, the purity of the synthesized product will be low and potassium titanate of various different morphologies will coexist.

[0006] The patent with publication number CN113403686B discloses a method for preparing potassium titanate whiskers for friction materials, using titanium dioxide and potassium source as raw materials, K2O-MoO3 composite solvent as solvent, and adopting flux method to prepare potassium titanate whiskers for friction materials. The production process of this method is complicated, and it is necessary to first prepare potassium tetratitanate from titanium source and potassium source, and then prepare potassium hexatitanate through washing and secondary sintering. The solvent will seriously corrode the sagger at high temperature, affecting the product quality, and a large amount of alkaline wastewater is generated during production.

[0007] The patent with publication number CN102304762A discloses a method for preparing potassium hexatitanate whiskers, which comprises mixing potassium carbonate and metatitanic acid at room temperature and then drying, calcining the precursor and performing water immersion treatment to prepare potassium hexatitanate whiskers. This method is prone to produce a large amount of by-products during the preparation process, which need to be removed by washing with water, which not only wastes raw materials but also increases a large amount of high-salt wastewater that is difficult to treat.

[0008] The patent with publication number CN115747967B discloses a method for preparing potassium hexatitanate whiskers, which comprises mixing titanium-containing raw materials and potassium-containing raw materials, sintering the mixture at a temperature of 600-800°C, dispersing it in water after cooling with the furnace, introducing acidic gas, adjusting the pH value, filtering and drying, and then sintering and cooling the dried product at a temperature of 1000-1250°C to obtain thick potassium hexatitanate whiskers with a diameter greater than 3 μm. This production method does not react sufficiently, requires the input of excessive titanium sources, and eventually all of them are lost and wasted, and the production process requires multiple calcinations and the introduction of acidic gas, which is not conducive to industrial production. Summary of the invention

[0009] The purpose of the present invention is to solve the problem of limitations commonly found in existing potassium titanate preparation methods. A method for preparing potassium titanate powder is proposed. By regulating the raw material ratio, pretreatment, mixing, surface treatment and calcination processes, a potassium titanate product having a whisker-like, tunnel-like and lamellar microstructure and high crystallinity is prepared. The potassium titanate product can be used as a friction material, a reinforcing material and a thermal insulation material in the field of new materials and high-tech.

[0010] In order to solve the above technical problems, the present invention provides a method for preparing potassium titanate powder, comprising the following steps:

[0011] (1) adding a dispersant to a titanium source slurry having a concentration of 20-40%, mixing, grinding, and sieving to obtain a titanium precursor;

[0012] (2) preparing a saturated potassium source solution, and adding it to the titanium precursor at a molar ratio of titanium to potassium of (2.5-3.5):1, and mixing them evenly to obtain a potassium titanate precursor slurry;

[0013] (3) adding a surfactant to the potassium titanate precursor slurry and spray granulating the slurry to obtain potassium titanate precursor particles with a particle size of 10 to 50 μm;

[0014] (4) adding an intercalating agent to potassium titanate precursor particles, mixing them evenly, calcining them, and grinding and crushing them to obtain the potassium titanate powder.

[0015] As a further description of the present invention, the titanium source in step (1) is one or more of rutile titanium dioxide, anatase titanium dioxide, orthotitanic acid, and metatitanic acid; the dispersant is one or more of sodium hexametaphosphate, sodium tripolyphosphate, sodium pyrophosphate, sodium dodecyl sulfate, polyvinyl pyrrolidone, and a cellulose derivative; the amount of the dispersant added is 0.1-0.5% of the dry weight of the titanium source; the grinding is wet ball milling, and the screening is 325 mesh sieve.

[0016] As a further description of the present invention, the potassium source in step (2) is one or more of potassium carbonate, potassium bicarbonate, and potassium hydroxide.

[0017] As a further description of the present invention, the surfactant described in step (3) is one or more of titanate, aluminate, stearic acid, oleic acid, and polysorbate, and the amount of surfactant added is 1-5% of the dry weight of the titanium source. The spray granulation equipment is preferably a centrifugal spray granulator, and the spray temperature is ≤300°C.

[0018] As a further description of the present invention, the intercalating agent in step (4) is one or more of potassium acetate, dimethyl sulfoxide, urea, graphite, and isopropylamine, and the amount of the intercalating agent added is 3-8% of the dry weight of the titanium source; the calcination equipment is preferably a muffle furnace, a roller kiln, a tunnel kiln or a push plate furnace, and the calcination carrier is preferably made of alumina, zirconia or a ceramic sagger with alumina or zirconia sprayed on the surface. The calcination heating rate is 3-8 °C / min, the calcination temperature is 900-1200 °C and is controlled within ±5 °C of the set temperature, and the insulation time is 2-6 h; the grinding and crushing equipment is preferably a Raymond mill, a jet mill or a pulverizer to ensure that the microscopic morphology of the potassium titanate powder is not destroyed.

[0019] The preparation method of potassium titanate powder of the present invention uses titanium oxide or hydroxide and potassium compound as reaction raw materials, completely dissolves a soluble potassium source, and then adds it into a titanium precursor, and then adopts a non-destructive spray granulation method to recrystallize the potassium source on the surface of the titanium precursor to obtain potassium titanate precursor particles with uniform titanium and potassium components, and the size of the potassium titanate precursor particles can be adjusted as required; and then, by controlling different calcination temperatures, insulation times, and impact and shear forces of grinding and crushing, potassium titanate powders with different microscopic morphologies and high crystallinity are prepared; and during the preparation process, a dispersant is added to improve the dispersion degree of the titanium source, and an intercalation agent and a surfactant are added to adjust the microscopic morphology of the potassium titanate powder.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. The preparation method of the present invention utilizes the potassium source recrystallization process to uniformly disperse the titanium source in the dispersant, and then recrystallizes the potassium source on the surface of the titanium source to obtain a potassium titanate precursor with a uniform mixture and a highly consistent titanium-potassium molar ratio, thereby improving the crystallinity of the potassium titanate powder after calcination and dispersion;

[0022] 2. Potassium titanate powders with different microscopic morphologies were prepared by adding intercalation agents, which greatly broadened the application of potassium titanate in the field of new materials. As a friction material, it is particularly suitable for making automobile brake pads, and as a thermal insulation material, it is particularly suitable for various types of thermal insulation;

[0023] 3. By adjusting the parameters of the spray granulator, the size of the potassium titanate precursor particles can be controlled, and then the microscopic morphology of the potassium titanate powder after calcination and crushing can be regulated to improve the applicability of the product;

[0024] 4. The preparation method of the present invention does not require the addition of co-solvents such as KCl, KF, KMnO4, K2WO4, and does not require water washing to remove the co-solvents after the preparation is completed. The preparation process is clean and friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a SEM image of the whisker-like potassium titanate powder obtained in Example 1;

[0026] Figure 2 is an XRD characterization diagram of the whisker-like potassium titanate powder obtained in Example 1;

[0027] Figure 3 is a SEM image of the tunnel-shaped potassium titanate powder obtained in Example 2;

[0028] Figure 4 is the XRD characterization diagram of the tunnel-shaped potassium titanate powder obtained in Example 2;

[0029] Figure 5 is a SEM image of the plate-like potassium titanate powder obtained in Example 3;

[0030] Figure 6 is the XRD characterization diagram of the plate-like potassium titanate powder obtained in Example 3;

[0031] Figure 7 is a SEM image of potassium titanate powder obtained in comparative example;

[0032] Figure 8 This is the XRD characterization diagram of potassium titanate powder obtained in the comparative example. DETAILED DESCRIPTION

[0033] The technical solutions in the embodiments of the present invention will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Any technician familiar with the art can make possible changes and modifications to the technical solutions of the present invention using the methods and technical contents of the present invention without departing from the scope of the technical solutions of the present invention, or modify them into equivalent embodiments of equivalent changes. Therefore, any simple modification, equivalent replacement, equivalent change and modification made according to the technical contents of the present invention without departing from the content of the technical solutions of the present invention should belong to the scope of protection of the technical solutions of the present invention.

[0034] Embodiment 1:

[0035] This embodiment provides a method for preparing potassium titanate powder, comprising the following steps:

[0036] (1) adding sodium dodecyl sulfate (0.1% by weight of dry weight of titanium dioxide) to a 20% anatase titanium dioxide slurry, mixing and ball milling, and then passing through a 325-mesh sieve to obtain a titanium precursor;

[0037] (2) preparing a saturated potassium carbonate solution, adding it to the titanium precursor at a titanium:potassium molar ratio of 3:1, and mixing them evenly to obtain a potassium titanate precursor slurry;

[0038] (3) adding 1% titanate ester to the potassium titanate precursor slurry, sending it into a centrifugal spray granulator, setting the spray temperature to 250°C and adjusting the spray granulator parameters to perform spray granulation to obtain dry potassium titanate precursor particles with a particle size of 10 μm;

[0039] (4) Add 3% graphite by dry weight of titanium dioxide to potassium titanate precursor particles, send them into a ball mill to mix evenly, then put them into a ceramic sagger made of alumina and send them into a tunnel kiln. Adjust the heating rate of the tunnel kiln to 3 °C / min and heat it to 1000±5 °C and keep it warm for 2 h for calcination synthesis. After sintering, use Raymond mill to grind and crush to obtain potassium titanate powder.

[0040] from Figure 1It can be seen that the potassium titanate prepared in this embodiment is whisker-like potassium titanate with obvious whisker structure, moderate aspect ratio, and evenly dispersed whiskers without obvious clusters, and can be widely used in reinforcing materials and friction materials. Figure 2 It can be seen that the potassium titanate prepared in this embodiment is potassium hexatitanate.

[0041] Embodiment 2:

[0042] This embodiment provides a method for preparing potassium titanate powder, comprising the following steps:

[0043] (1) adding sodium hexametaphosphate (0.3% by dry weight of metatitanic acid) to a 30% concentration of metatitanic acid slurry, mixing and ball milling, and then passing through a 325 mesh sieve to obtain a titanium precursor;

[0044] (2) preparing a saturated potassium bicarbonate solution, adding it to the titanium precursor at a titanium:potassium molar ratio of 3:1, and mixing them evenly to obtain a potassium titanate precursor slurry;

[0045] (3) adding 2.5% oleic acid to the potassium titanate precursor slurry, sending the slurry into a centrifugal spray granulator, setting the spray temperature to 220°C and adjusting the spray granulator parameters to perform spray granulation, and obtaining dry potassium titanate precursor particles with a particle size of 20 μm;

[0046] (4) Add 5% urea by dry weight of metatitanic acid to the potassium titanate precursor particles, send them into a ball mill and mix them evenly, then put them into a ceramic sagger made of zirconia and send them into a roller kiln. Adjust the heating rate of the roller kiln to 5 °C / min and heat it to 1100±5 °C and keep it warm for 4 h for calcination synthesis. After sintering, use a jet mill to grind and pulverize them. After grinding and pulverizing, tunnel-shaped potassium titanate powder is obtained.

[0047] from Figure 3 It can be seen that the potassium titanate prepared in this embodiment is a tunnel-shaped potassium titanate with an obvious columnar structure. Figure 4 It can be seen that the potassium titanate prepared in this embodiment is potassium hexatitanate.

[0048] Embodiment 3:

[0049] This embodiment provides a method for preparing potassium titanate powder, comprising the following steps:

[0050] (1) adding sodium tripolyphosphate (0.5% by dry weight of orthotitanic acid) to a 40% orthotitanic acid slurry, mixing and ball milling, and then passing through a 325-mesh sieve to obtain a titanium precursor;

[0051] (2) preparing a saturated potassium carbonate solution, adding it to the titanium precursor at a titanium:potassium molar ratio of 3.5:1, and mixing them evenly to obtain a potassium titanate precursor slurry;

[0052] (3) adding 5% polysorbate to the potassium titanate precursor slurry, feeding the slurry into a centrifugal spray granulator, setting the spray temperature to 230° C. and adjusting the spray granulator parameters to perform spray granulation, and obtaining dry potassium titanate precursor particles with a particle size of 50 μm;

[0053] (4) Add 8% isopropylamine by dry weight of orthotitanic acid to the potassium titanate precursor particles, send them into a ball mill to mix evenly, then put them into a ceramic sagger with zirconium oxide sprayed on the surface and send them into a push-plate kiln. Adjust the push-plate kiln heating rate to 8 °C / min and heat it to 1200±5 °C and keep it warm for 4 h for calcination synthesis. After sintering, use a jet mill to grind and pulverize them. After grinding and pulverizing, lamellar potassium titanate powder is obtained.

[0054] from Figure 1 It can be seen that the potassium titanate prepared in this embodiment has a flaky structure, which is a plate-like potassium titanate with uniform particle size and good dispersibility. The flaky structure of potassium titanate can better prevent or slow down the transfer of energy to the brake pad during braking and absorb the noise generated during braking. It is particularly suitable for making new environmentally friendly automobile brake pads. Figure 6 It can be seen that the potassium titanate prepared by this method is potassium hexatitanate with good crystallinity.

[0055] The innovation of the present invention lies in that the potassium source and titanium source involved in the synthesis reaction can be fully mixed in the method, a dispersant is added during the preparation process to improve the dispersion degree of the titanium source, an intercalating agent and a surfactant are added to adjust the microscopic morphology of the potassium titanate powder, and potassium titanate powder with different particle size distributions is prepared by adjusting the size of the potassium titanate reaction precursor particles.

[0056] Comparative Example:

[0057] (1) preparing a 40% concentration of orthotitanic acid slurry, uniformly dispersing it and passing it through a 325-mesh sieve to obtain a titanium precursor;

[0058] (2) preparing a saturated potassium hydroxide solution, adding it to the titanium precursor at a titanium:potassium molar ratio of 3:1, and mixing them evenly to obtain a potassium titanate precursor slurry;

[0059] (3) Drying the potassium titanate precursor slurry in an oven, crushing the bulk material after drying, and passing it through a 200-mesh sieve;

[0060] (4) The potassium titanate precursor powder is loaded into a ceramic sagger with zirconium oxide sprayed on the surface, and sent to a roller kiln for calcination. The heating rate of the roller kiln is adjusted to 5°C / min and the temperature is raised to 1000±5°C and kept at this temperature for 4 hours for calcination synthesis. After sintering, it is ground and pulverized by a jet mill to obtain potassium titanate powder.

[0061] from Figure 7It can be seen that the potassium titanate powder particles prepared in this comparative example have irregular shapes and very uneven sizes. The phenomenon that particles of different morphologies agglomerate together is very obvious, and it is very difficult to further disperse them. Figure 8 It can be seen that the potassium titanate prepared in this comparison has poor crystallinity and has a lot of unreacted impurities remaining.

[0062] The above is only the best embodiment of the present invention. It should be pointed out that, for ordinary technicians in this field, without departing from the principle of the present invention, the technical solution of the present invention can be modified or replaced by equivalents, which can also achieve the technical effect of the present invention and should also be regarded as belonging to the protection scope of the present invention.

Claims

1. A method for preparing potassium titanate powder, characterized in that: The following steps are involved: (1) adding a dispersant to a titanium source slurry having a concentration of 20-40%, mixing, grinding, and sieving to obtain a titanium precursor; (2) preparing a saturated potassium source solution, and adding it to the titanium precursor at a molar ratio of titanium to potassium of (2.5-3.5):1, and mixing them evenly to obtain a potassium titanate precursor slurry; (3) adding a surfactant to the potassium titanate precursor slurry and spray granulating the slurry to obtain potassium titanate precursor particles with a particle size of 10 to 50 μm; (4) adding an intercalating agent to potassium titanate precursor particles, mixing them evenly and then calcining them for synthesis, and grinding and crushing them to obtain potassium titanate powder having a whisker-like, tunnel-like or lamellar-like microstructure; The titanium source in step (1) is one or more of rutile titanium dioxide, anatase titanium dioxide, orthotitanic acid, and metatitanic acid; the dispersant is one or more of sodium hexametaphosphate, sodium tripolyphosphate, sodium pyrophosphate, sodium dodecyl sulfate, polyvinyl pyrrolidone, and cellulose derivatives; the amount of the dispersant added is 0.1-0.5% of the dry weight of the titanium source; The intercalating agent in step (4) is one or more of potassium acetate, dimethyl sulfoxide, urea, graphite, and isopropylamine, and the amount of the intercalating agent added is 3-8% of the dry weight of the titanium source.

2. The method for preparing potassium titanate powder according to claim 1, characterized in that: The potassium source in step (2) is one or more of potassium carbonate, potassium bicarbonate and potassium hydroxide.

3. The method for preparing potassium titanate powder according to claim 1, characterized in that: The surfactant described in step (3) is one or more of titanate, aluminate, stearic acid, oleic acid, and polysorbate, and the amount of the surfactant added is 1-5% of the dry weight of the titanium source.

4. The method for preparing potassium titanate powder according to claim 1, characterized in that: The grinding in step (1) is wet ball milling, and the screening is 325 mesh sieve.

5. The method for preparing potassium titanate powder according to claim 1 or 3, characterized in that: The spray temperature of the spray granulation in step (3) is ≤300°C.

6. The method for preparing potassium titanate powder according to claim 1 or 4, characterized in that: In step (4), the heating rate of calcination is 3-8 °C / min, the calcination temperature is 900-1200 °C, and the holding time is 2-6 h.

7. The method for preparing potassium titanate powder according to claim 6, characterized in that: The carrier for calcination in step (4) is made of alumina, zirconia or a ceramic sagger with alumina or zirconia sprayed on the surface.

Images