A medium-high temperature resistant nano ceramic coating, ceramic membrane and preparation method thereof

Abstract

The application discloses a kind of high-temperature corrosion-resistant anticorrosion nano ceramic coatings, main component and its weight percentage include: nano alumina 20-30 parts, nano boron nitride 10-15 parts, glass powder 10-15 parts, silica sol 40-50 parts, nano magnesium oxide 1-2 parts, nano zirconium oxide 1-2 parts, mica powder 1-2 parts, borax 2-3 parts, sepiolite fiber 0.5-2.0 parts, dispersing agent 0.5-1 part.The application stably mixes a variety of ceramic powders in silica sol, and introduces dispersing agent, sepiolite fiber and glass powder, forms uniform, not easy to settle and the film-forming property of better all inorganic nano ceramic coating;Further combined with step sintering and the secondary coating process of silica sol, promote to obtain dense ceramic coating, effectively solve the problem such as poor adhesion, easy to crack of traditional inorganic coating;And the preparation method involved is relatively simple, easy to operate, suitable for popularization and application.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of inorganic protective film, and particularly relates to a medium-high temperature resistant inorganic nano ceramic coating, a ceramic film and a preparation method thereof. BACKGROUND

[0002] With the increasing demand for energy due to rapid development of science and technology, oil and gas exploration is gradually expanding to ultra-deep wells, high temperature and high pressure, and high corrosion environment, and involves a variety of unconventional oil and gas resources. For high temperature, high pressure, high corrosion oil and gas resource exploitation, the oil pipe often contacts high concentration of CO2, Cl2, H2S and other corrosive gases during the exploitation process, and some exploitation environments must also face the problem of water internal corrosion. Such a harsh development environment makes most commonly used carbon alloy steel pipes and nickel alloy pipes unable to serve for a long time; higher requirements are put forward for the high corrosion resistance and high temperature, high pressure performance of the oil pipe.

[0003] Titanium alloy has the advantages of high strength, low density, good corrosion resistance, low elastic modulus and high fatigue resistance, and becomes the first choice material for the oil pipe industry. However, titanium alloy exposed to high temperature and corrosive environment is still prone to stress corrosion and crevice corrosion and other problems, thereby causing cracking phenomenon, and still needs to be subjected to corrosion protection treatment on the surface. Covering a high-temperature resistant protective film layer on the surface of the alloy can increase the service time of the titanium alloy pipe in humid atmosphere and seawater medium, so as to cope with various problems such as pitting corrosion, acid corrosion and stress corrosion.

[0004] At present, the commercial protective film used on the surface of titanium alloy is mainly silicone coating. Although the silicone coating is easy to form a film and easy to construct, it can only be used for a long time below 300 DEG C. When the temperature is higher, cracks are easily generated on the surface of the film layer, and the silicone component in the film layer will be carbonized and decomposed, resulting in continuous peeling of the film layer. If in a water vapor environment, the titanium alloy is prone to corrosion. Although the preparation process of the high-temperature resistant inorganic ceramic film (higher than 700 DEG C) is relatively mature, the adhesion and film forming performance are poor, and it cannot be used on the surface of titanium alloy. At present, the corrosion-resistant ceramic film used in the medium-high temperature region is still blank in the preparation process, and part of the process still cannot be separated from the use of organic silicon resin, and cannot meet the service life requirements of the workpiece, and the mechanical properties are limited. Therefore, it is of important research and application significance to further develop a full inorganic ceramic film resistant to medium-high temperature and capable of guaranteeing good mechanical properties. SUMMARY

[0005] The main purpose of the present application is to solve the problems and deficiencies in the prior art, and to provide a full inorganic nano ceramic coating resistant to medium-high temperature. The coating can form a ceramic film uniformly covering the titanium alloy and other workpieces, and effectively solve the problems of low film forming property, poor adhesion and easy cracking of traditional inorganic coating.

[0006] To achieve the above object, the technical scheme adopted by the present application is:

[0007] A kind of nano ceramic coating resistant to medium-high temperature and corrosion, the main components and its weight fraction excluding dispersing solvent include: nano alumina 20-30 parts, nano boron nitride 10-15 parts, glass powder 10-15 parts, silica sol 40-50 parts, nano magnesium oxide 1-2 parts, nano zirconium oxide 1-2 parts, mica powder 1-2 parts, borax 2-3 parts, sepiolite fiber 0.5-2.0 parts, dispersing agent 0.5-1 part.

[0008] In the above scheme, the average particle size of the nano alumina, nano boron nitride, nano magnesium oxide and nano zirconium oxide is 20-50 nm.

[0009] In the above scheme, the main components of the glass powder are silicon oxide and sodium oxide; its particle size is 15-25 nm, and its melting point is 380-420℃.

[0010] In the above scheme, the silica sol is used as a slurry binder, with a silica content of 38-42wt% and an average particle size of 8-15 nm; the present application uses silica sol to bond nano ceramic powder and mica powder on the surface of titanium alloy pipe, and combines glass powder and a small amount of borax, which helps to bond various nano ceramic particles and sepiolite fibers together to form a dense film layer during high-temperature sintering.

[0011] In the above scheme, the average particle size of the mica powder is 45-55 nm; the present application utilizes the difference in particle size between nano ceramic powder and mica powder to make the film layer on the surface of titanium alloy more uniform and dense.

[0012] In the above scheme, the size of the sepiolite fiber is 50-200 nm; the present application utilizes the unique layer chain structure of sepiolite fiber and its good adsorption and rheological properties to make the film layer more easily spread on the surface of titanium alloy, and the film layer is uniform and dense after sintering, and is not easy to fall off.

[0013] In the above scheme, the dispersing agent is sodium tripolyphosphate.

[0014] In the above scheme, the dispersing solvent contains water, and the amount of water used is 8-15 parts

[0015] Further, the dispersing solvent also contains ethanol, and the content of ethanol is 35-45 parts.

[0016] The above preparation method of a nano ceramic coating resistant to medium-high temperature and corrosion includes the following steps:

[0017] 1) Weighed nano alumina, nano boron nitride, nano magnesium oxide, nano zirconium oxide, glass powder, dispersing agent, borax, sepiolite fiber and mica powder are added for ball milling to obtain a composite powder;

[0018] 2) to the resulting composite powder, add a silica hydrosol, then add a dispersion solvent, stir until uniform, to obtain a nano-ceramic coating resistant to medium-high temperature corrosion.

[0019] The application also provides a method for preparing a nano-ceramic film resistant to medium-high temperature corrosion, comprising the following steps:

[0020] 1) clean and roughen the surface of the workpiece;

[0021] 2) apply the nano-ceramic coating resistant to medium-high temperature corrosion to the surface of the workpiece treated in step 1), and allow it to dry naturally to form a film;

[0022] 3) perform a first heat treatment, after cooling, apply a silica hydrosol to the surface, and perform a second heat treatment, to form the nano-ceramic film resistant to medium-high temperature corrosion on the surface of the workpiece.

[0023] In the above scheme, the workpiece is a titanium alloy workpiece or a tungsten alloy workpiece, etc.

[0024] In the above scheme, the cleaning step comprises the steps of removing oil with acetone, acid pickling with hydrochloric acid, and water washing, etc.

[0025] In the above scheme, the roughening treatment uses 100-mesh sandpaper.

[0026] In the above scheme, the first heat treatment is performed at a temperature of 500-700℃, at a heating rate of 2-4℃ / min, and for a holding time of 3-5h; the second heat treatment is performed at a temperature of 500-700℃, at a heating rate of 2-4℃ / min, and for a holding time of 1-3h.

[0027] In the application, ceramic powders are stably mixed in a silica sol, and a dispersant is added to form a slurry, the ceramic powders are bonded together by virtue of the strong bonding force and medium-high temperature resistance (350-800℃) of the silica sol, then step-by-step sintering and secondary coating of the silica sol are performed to obtain a densified ceramic coating.

[0028] Compared with the prior art, the application has the following beneficial effects:

[0029] 1) In the application, nano-alumina, nano-boron nitride, nano-magnesium oxide, and nano-zirconium oxide, etc. are stably mixed in a silica sol, and a dispersant, sepiolite fiber, mica powder, and glass powder are added to form a slurry, to obtain a uniform, non-settleable, and good film-forming inorganic nano-ceramic coating resistant to medium-high temperature;

[0030] 2) The application further combines step-by-step sintering and secondary coating of the silica sol to promote the formation of a dense ceramic coating, and to achieve good adhesion and crack resistance, etc.

[0031] 3) The nano-ceramic coating obtained by the present application has good film-forming property and adhesion, and can effectively improve the problems of low film-forming property, poor adhesion and easy cracking of traditional inorganic coatings; and the preparation method is relatively simple, easy to operate and has wide applicability. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 XRD pattern of the ceramic film obtained in Example 1;

[0033] Figure 2 SEM pattern of the ceramic film obtained in Example 1;

[0034] Figure 3 SEM pattern of the ceramic film obtained in Example 1 after high-temperature resistance test;

[0035] Figure 4 Surface morphology pattern of the ceramic film obtained in Example 1 after high-temperature treatment;

[0036] Figure 5 Photo of the ceramic film obtained in Example 1 after 80℃ water bath treatment;

[0037] Figure 6 Photo of the ceramic film obtained in Example 1 after hydrothermal treatment and before 200℃ hydrothermal treatment;

[0038] Figure 7 Photo of the titanium alloy sample coated with ceramic coating in Example 1 before and after acid resistance test;

[0039] Figure 8 Photo of the titanium alloy sample coated with ceramic coating in Example 1 before and after alkali resistance test;

[0040] Figure 9 Photo of the titanium alloy sample coated with ceramic coating in Example 1 before and after salt resistance test;

[0041] Figure 10 SEM pattern of the ceramic film obtained in Comparative Example 1;

[0042] Figure 11 SEM pattern of the ceramic film obtained in Example 2;

[0043] Figure 12 SEM pattern of the ceramic film obtained in Example 3. DETAILED DESCRIPTION

[0044] In order to make the advantages of the present application clearer and more explicit, the present application will be further described in detail with the following specific examples and the accompanying drawings. The specific examples described herein are only used to illustrate the present application and not to limit the protection scope of the present application. After reading the present application, those skilled in the art can make various equivalent modifications of the present application, which fall within the scope defined by the appended claims.

[0045] In the following examples, the average particle size of the nano-alumina used is 30 nm; the average particle size of the nano-boron nitride used is 50 nm; the average particle size of the nano-magnesium oxide used is 30 nm; and the average particle size of the nano-zirconium oxide used is 20 nm.

[0046] The glass powder used is a commercially available glass powder, the main components of which are silicon oxide and sodium oxide; the average particle size thereof is 20 nm, and the melting point thereof is about 400°.

[0047] The silicon sol used has a silicon oxide content of 40 wt% and an average particle size of 10 nm.

[0048] The sepiolite fiber used is a commercially available sepiolite fiber with a size of 50-200 nm.

[0049] The dispersant used is sodium tripolyphosphate.

[0050] Example 1

[0051] A kind of high-temperature-resistant all-inorganic nano-ceramic coating, film layer, its preparation method comprises the following steps:

[0052] The nano-ceramic coating:

[0053] 1) The raw materials of the ceramic slurry are weighed according to the proportion, and the weight percentage of each raw material and its weight percentage includes: 20 parts of nano-alumina, 10 parts of nano-boron nitride, 10 parts of glass powder, 40 parts of silicon sol, 1 part of nano-magnesium oxide, 1 part of nano-zirconium oxide, 1 part of mica powder, 2 parts of borax, 0.5 parts of sodium tripolyphosphate, and 1.0 parts of sepiolite fiber;

[0054] 2) The weighed nano-ceramic powder (nano-alumina, nano-boron nitride, nano-magnesium oxide, and nano-zirconium oxide; the same below), glass powder, dispersant, borax, sepiolite fiber, and mica powder are added to a ball mill and mixed and ground thoroughly, wherein the grinding material is selected as ZrO2 balls, the ball-to-material ratio is 5:1, the grinding speed is 300 rpm, the grinding time is 5 hours, and a small amount of ethanol is added as a grinding aid;

[0055] 3) The silicon sol is added to the ground composite powder, and a small amount of deionized water and 40 parts of ethanol are added several times to obtain a uniform and not easily settled high-temperature-resistant all-inorganic nano-ceramic coating.

[0056] High-temperature resistant all-inorganic nano ceramic film layer:

[0057] (1) The surface of the titanium alloy workpiece is subjected to acetone degreasing, hydrochloric acid pickling, water washing, and sandpaper polishing roughening treatment (100 mesh sandpaper is used);

[0058] (2) The obtained high-temperature resistant all-inorganic nano ceramic coating is uniformly coated on the surface of the workpiece by using the manual brushing method, and then placed in a clean environment for natural drying to form a film;

[0059] (3) Put into the muffle furnace, heat to 700℃ at a rate of 2℃ / min, and keep for 3h; after taking out the hot workpiece, cool to room temperature, then uniformly brush a layer of silica sol on the surface, so that the defects on the surface after the first film formation are completely covered, and then place it in a tube furnace for the second heat treatment, the specific steps are as follows: heat to 700℃ at a rate of 2℃ / min, and keep for 1h, thus obtaining the workpiece with attached high-temperature resistant anticorrosive nano ceramic film.

[0060] The obtained workpiece samples are subjected to high-temperature resistance, salt resistance, alkali resistance, acid resistance, normal temperature water resistance, and hydrothermal test, and the specific steps and test results are as follows:

[0061] High-temperature resistance test: the sample is placed in a muffle furnace for heat treatment at 800℃, the heating rate is 2℃ / min, and the holding time is 2h.

[0062] Salt resistance test: the sample is soaked in a 3.5% NaCl solution for fifteen days, and the surface of the sample is observed for any obvious changes or peeling.

[0063] Alkali resistance test: the sample is soaked in a 3.5% NaOH solution for fifteen days, and the surface of the sample is observed for any obvious changes or peeling.

[0064] Acid resistance test: 3.5% HCl solution is dropped on the sample for 12 hours, and the surface of the sample is observed for any obvious changes or peeling.

[0065] Normal temperature water resistance test: the sample is placed in a beaker and transferred to an 80℃ water bath, and the state of the film layer on the surface of the sample is observed after 3 days.

[0066] Hydrothermal test: the sample is placed in a hydrothermal kettle, deionized water is added, and then sealed and placed in a muffle furnace, the temperature is set to 200℃, and after 12h, the sample is taken out and the state of the film layer on the surface of the sample is observed.

[0067] Figure 1 It can be seen that the main phase composition of the ceramic film is Al2O3, ZrO2 and MgO. Figure 2It can be seen that the ceramic film layer formed is very dense, and the nanoceramic particles are dispersed between the film layers, and the sepiolite fibers with a length of 5 μm or more are also embedded in the ceramic film. The hardness of the ceramic film obtained by a hardness tester is 5H.

[0068] Figure 3 The scanning electron microscope image of the ceramic film can be seen that the film layer morphology changes little after heat treatment at 800°C, indicating that the film layer has good high temperature resistance. Figure 4 The photo of the film layer after high temperature resistance can be seen that the coating changes little. Figure 5 and Figure 6 show that the ceramic film is relatively dense and has certain water resistance. Figure 7 、 Figure 8 and Figure 9 show that the surface of the ceramic film does not change significantly after the alkali resistance, acid resistance and salt resistance experiments.

[0069] Comparative Example 1

[0070] A kind of mid-high temperature resistant all-inorganic nanoceramic coating, film layer, its preparation method comprises the following steps:

[0071] The nanoceramic coating comprises:

[0072] 1) The raw materials of the ceramic slurry are weighed according to the proportion, and the raw materials and the weight percentage thereof include: 20 parts of nanometer alumina, 10 parts of nanometer boron nitride, 10 parts of glass powder, 40 parts of silica sol, 1 part of nanometer magnesium oxide, 1 part of nanometer zirconium oxide, 1 part of mica powder, 2 parts of borax, and 0.5 parts of sodium tripolyphosphate dispersant;

[0073] 2) The weighed nanoceramic powder, glass powder, dispersant, borax and mica powder are added to the ball mill and mixed and ground, wherein the grinding material is selected as ZrO2 ball, the ball material ratio is 5:1, the grinding speed is 300 rpm, the grinding time is 5 hours, and a small amount of ethanol is added as a grinding aid;

[0074] 3) Add silica sol to the ground composite powder, and add a small amount of 10 parts of deionized water and 40 parts of ethanol for full stirring to obtain a uniform and not easily settled mid-high temperature resistant all-inorganic nanoceramic coating.

[0075] Mid-high temperature resistant all-inorganic nanoceramic film layer:

[0076] (1) The surface of the titanium alloy workpiece should be treated with acetone degreasing, hydrochloric acid pickling, washing and sandpaper polishing roughening (100 mesh sandpaper is used);

[0077] (2) The obtained mid-high temperature resistant all-inorganic nanoceramic coating is uniformly coated on the surface of the workpiece by hand brushing method, and then placed in a clean environment for natural drying to form a film;

[0078] (3) Put into the muffle furnace to 700℃ at a rate of 2℃ / min for 3h; after the heat treatment of the workpiece is taken out, cool to room temperature, then evenly brush the surface of the silicon sol, after the surface is dry, placed in a tube furnace for the second time heat treatment, the specific steps are, to 700℃ at a rate of 2℃ / min, 1h, the workpiece is obtained to avoid the adhesion of high temperature corrosion resistant nanometer ceramic film.

[0079] Figure 10 It can be seen that the ceramic film without adding sepiolite fiber is composed of ceramic film layer and ceramic particles. The sintered film layer is easy to crack and has low strength, which does not meet the requirements.

[0080] Example 2

[0081] A kind of high temperature resistant all-inorganic nanometer ceramic coating, film layer, its preparation method comprises the following steps:

[0082] The nanometer ceramic coating:

[0083] 1) The raw materials of the ceramic slurry are weighed according to the ratio, and the weight percentage of each raw material includes: 20 parts of nano alumina, 10 parts of nano boron nitride, 10 parts of glass powder, 40 parts of silicon sol, 1 part of nano magnesium oxide, 1 part of nano zirconium oxide, 1 part of mica powder, 2 parts of borax, 0.5 parts of sodium tripolyphosphate dispersant, and 0.5 parts of sepiolite fiber;

[0084] 2) The weighed nanometer ceramic powder, glass powder, dispersant, borax, sepiolite fiber and mica powder are added to the ball mill and mixed and ground, wherein the grinding material is selected as ZrO2 ball, the ball material ratio is 5:1, the speed is 300 rpm, the grinding time is 5 hours, and a small amount of ethanol is added as grinding aid;

[0085] 3) Add silicon sol to the ground composite powder, and add a small amount of 10 parts of deionized water and 40 parts of ethanol for several times and stir well to obtain a uniform and not easy to settle high temperature resistant all-inorganic nanometer ceramic coating.

[0086] High temperature resistant all-inorganic nanometer ceramic film layer:

[0087] (1) The surface of the titanium alloy workpiece should be degreased with acetone, pickled with hydrochloric acid, washed with water and sanded to roughen (100 mesh sandpaper is used);

[0088] (2) The obtained high temperature resistant all-inorganic nanometer ceramic coating is evenly coated on the surface of the workpiece by hand brushing method, and then placed in a clean environment for natural drying to form a film;

[0089] (3) put into the muffle furnace to 700℃ at a rate of 2℃ / min, heat preservation 3h; after the workpiece is taken out after heating, cool to room temperature, then evenly brush a layer of silica sol on its surface, after the surface is dry, place in the tube furnace for the second time heat treatment, the specific steps are, to 700℃ at a rate of 2℃ / min, heat preservation 1h, the workpiece avoiding the adhesion of the high-temperature corrosion-resistant nanoceramic film is obtained.

[0090] Figure 11 It can be seen that the ceramic film added with 0.5 parts of sepiolite fiber is assembled by ceramic particles.

[0091] Example 3

[0092] A high-temperature-resistant all-inorganic nanoceramic coating, film layer, and a preparation method thereof, comprising the following steps:

[0093] The nanoceramic coating:

[0094] 1) The raw materials of the ceramic slurry are weighed according to the proportion, and the weight percentage of each raw material includes: 20 parts of nano-alumina, 10 parts of nano-boron nitride, 10 parts of glass powder, 40 parts of silica sol, 1 part of nano-magnesium oxide, 1 part of nano-zirconium oxide, 1 part of mica powder, 2 parts of borax, 0.5 parts of sodium tripolyphosphate dispersant, and 1.5 parts of sepiolite fiber;

[0095] 2) The weighed nanoceramic powder, glass powder, dispersant, borax, and mica powder are added to the ball mill and mixed and ground thoroughly, wherein the grinding material is selected as ZrO2 ball, the ball-to-material ratio is 5:1, the grinding speed is 300 rpm, and a small amount of ethanol is added as a grinding aid;

[0096] 3) Add silica sol to the ground composite powder, and add a small amount of 10 parts of deionized water and 40 parts of ethanol for several times and stir thoroughly to obtain a uniform and non-settling high-temperature-resistant all-inorganic nanoceramic coating.

[0097] High-temperature-resistant all-inorganic nanoceramic film layer:

[0098] (1) The surface of the titanium alloy workpiece should be treated with acetone degreasing, hydrochloric acid pickling, water washing, and sandpaper polishing roughening (100 mesh sandpaper is used);

[0099] (2) The obtained high-temperature-resistant all-inorganic nanoceramic coating is evenly coated on the surface of the workpiece by hand brushing method, and then placed in a clean environment for natural drying to form a film;

[0100] (3) put into the muffle furnace to 700℃ at a rate of 2℃ / min, heat preservation 3h; after the heat treatment of the workpiece, cooling to room temperature, then evenly brush a layer of silica sol on the surface, after the surface is dry, placed in a tube furnace for the second heat treatment, the specific steps are, to 700℃ at a rate of 2℃ / min, heat preservation 1h, the workpiece avoiding the adhesion of the corrosion-resistant nano ceramic film is obtained.

[0101] Figure 12 It can be seen that the ceramic membrane sepiolite fiber is added 1.5 parts of sepiolite fiber, which is gathered on the surface of the membrane layer, part of which is combined with the nano ceramic particles, and part of which is not easy to disperse uniformly.

[0102] Example 4

[0103] A kind of medium-high temperature resistant all-inorganic nano ceramic coating, membrane layer, its preparation method comprises the following steps:

[0104] The nano ceramic coating:

[0105] 1) the raw materials of ceramic slurry are weighed according to the proportion, and the weight percentage of each raw material includes: 20 parts of nano alumina, 10 parts of nano boron nitride, 10 parts of glass powder, 40 parts of silica sol, 1 part of nano magnesium oxide, 1 part of nano zirconium oxide, 1 part of mica powder, 2 parts of borax, 0.5 parts of sodium tripolyphosphate dispersant, 1.0 parts of sepiolite fiber;

[0106] 2) the weighed nano ceramic powder, glass powder, dispersant, borax, sepiolite fiber and mica powder are added to the ball mill and mixed uniformly and ground thoroughly, wherein the grinding material is selected as ZrO2 ball, the ball material ratio is 5:1, the grinding speed is 300 rpm, and a small amount of ethanol is added as grinding aid;

[0107] 3) add silica sol to the ground composite powder, and add a small amount of 10 parts of deionized water and 40 parts of ethanol for several times and stir thoroughly to obtain a uniform and not easy to settle medium-high temperature resistant all-inorganic nano ceramic coating.

[0108] Medium-high temperature resistant all-inorganic nano ceramic membrane layer:

[0109] (1) the surface of the titanium alloy workpiece should be degreased with acetone, pickled with hydrochloric acid, washed with water and sanded to roughen (100 mesh sandpaper is used);

[0110] (2) the obtained medium-high temperature resistant all-inorganic nano ceramic coating is evenly coated on the surface of the workpiece by hand brushing method, and then placed in a clean environment for natural drying to form a film;

[0111] (3) Put into the muffle furnace to 600℃ at a rate of 2℃ / min for 3h; after the heat treatment, the workpiece is taken out, cooled to room temperature, then evenly brushed a layer of silica sol on its surface, after the surface is dry, placed in a tube furnace for the second heat treatment, the specific steps are, heated to 600℃ at a rate of 2℃ / min, and kept for 1h, thus the workpiece with the attached anti-corrosion nano ceramic film is obtained.

[0112] Example 5

[0113] A kind of mid-high temperature resistant all-inorganic nano ceramic coating, film layer, its preparation method comprises the following steps:

[0114] The nano ceramic coating:

[0115] 1) The raw materials of the ceramic slurry are weighed according to the proportion, and the weight percentage of each raw material includes: 25 parts of nano alumina, 13 parts of nano boron nitride, 12 parts of glass powder, 45 parts of silica sol, 2 parts of nano magnesium oxide, 2 parts of nano zirconium oxide, 2 parts of mica powder, 3 parts of borax, 1 part of sodium tripolyphosphate dispersant, and 1 part of sepiolite fiber;

[0116] 2) The weighed nano ceramic powder, glass powder, dispersant, borax, sepiolite fiber and mica powder are added to the ball mill and mixed and ground thoroughly, wherein the grinding material is selected as ZrO2 ball, the ball-to-material ratio is 5:1, the grinding speed is 300 rpm, and a small amount of ethanol is added as a grinding aid;

[0117] 3) Add silica sol to the ground composite powder, and add a small amount of 10 parts of deionized water and 40 parts of ethanol for several times and stir thoroughly to obtain a uniform and not easily settled mid-high temperature resistant all-inorganic nano ceramic coating.

[0118] The mid-high temperature resistant all-inorganic nano ceramic film layer:

[0119] (1) The surface of the titanium alloy workpiece should be degreased with acetone, pickled with hydrochloric acid, washed with water, and sanded and roughened (100 mesh sandpaper is used);

[0120] (2) The obtained mid-high temperature resistant all-inorganic nano ceramic coating is evenly coated on the surface of the workpiece by hand brushing method, and then placed in a clean environment for natural drying to form a film;

[0121] (3) Put into the muffle furnace to 800℃ at a rate of 2℃ / min for 3h; after the heat treatment, the workpiece is taken out, cooled to room temperature, then evenly brushed a layer of silica sol on its surface, after the surface is dry, placed in a tube furnace for the second heat treatment, the specific steps are, heated to 800℃ at a rate of 2℃ / min, and kept for 1h, thus the workpiece with the attached anti-corrosion nano ceramic film is obtained.

[0122] Comparative Example 2

[0123] A kind of high temperature resistant full inorganic nano ceramic coating, film layer, its preparation method includes the following steps:

[0124] The nano ceramic coating:

[0125] 1) according to the proportion of the ceramic slurry, each raw material is weighed, each raw material and its weight percentage include: nano alumina 20 parts, nano boron nitride 10 parts, glass powder 10 parts, silica sol 40 parts, nano magnesium oxide 1 part, nano zirconium oxide 1 part, mica powder 1 part, borax 2 parts, sodium tripolyphosphate dispersant 0.5 parts, sepiolite fiber 1.0 parts

[0126] 2) the weighed nano ceramic powder, glass powder, dispersant, borax and mica powder are added to the ball mill and mixed uniformly and ground sufficiently, wherein the grinding material is selected as ZrO2 ball, the ball material ratio is 5:1, the speed is 300 rpm, and a small amount of ethanol is added as grinding aid, and the grinding is carried out for 5 hours;

[0127] 3) add silica sol to the ground composite powder, and add a small amount of 10 parts of deionized water and 40 parts of ethanol for several times, and fully stir to obtain uniform and not easy to settle high temperature resistant full inorganic nano ceramic coating.

[0128] High temperature resistant full inorganic nano ceramic film layer:

[0129] (1) the surface of titanium alloy workpiece should be degreased with acetone, pickled with hydrochloric acid, washed with water and sanded to roughen (100 mesh sandpaper is used);

[0130] (2) the obtained high temperature resistant full inorganic nano ceramic coating is uniformly coated on the surface of the workpiece by using the method of manual brushing, and then placed in a clean environment to dry naturally to form a film;

[0131] (3) put into the muffle furnace, and heat to 700℃ at a rate of 2℃ / min, and keep for 3h.

[0132] After testing, the surface of the obtained film layer has defects, and the corresponding high temperature resistance and corrosion resistance are poor.

[0133] The above content is only an example and description of the present application, and those skilled in the art can make various modifications or supplements to the described specific embodiments or use similar ways to replace, as long as it does not deviate from the invention or exceed the scope defined by the present claims, which shall belong to the protection scope of the present application.

Claims

1. A nano-ceramic coating resistant to medium and high temperatures and corrosion, characterized in that, The main components, excluding the dispersing solvent, and their respective weight percentages include: 20-30 parts nano-alumina, 10-15 parts nano-boron nitride, 10-15 parts glass powder, 40-50 parts silica hydrosol, 1-2 parts nano-magnesium oxide, 1-2 parts nano-zirconia, 1-2 parts mica powder, 2-3 parts borax, 0.5-2.0 parts sepiolite fiber, and 0.5-1 part dispersant; The glass powder is mainly composed of silicon oxide and sodium oxide, with a melting point of 380-420℃.

2. The nano-ceramic coating according to claim 1, characterized in that, The average particle size of the nano-alumina, nano-boron nitride, nano-magnesium oxide, and nano-zirconia is 20-50 nm.

3. The nano-ceramic coating according to claim 1, characterized in that, The glass powder has a particle size of 15-25 nm.

4. The nano-ceramic coating according to claim 1, characterized in that, The silica hydrosol contains 38-42 wt% silica and has an average particle size of 8-15 nm.

5. The nano-ceramic coating according to claim 1, characterized in that, The average particle size of the mica powder is 45-55 nm; the size of the sepiolite fiber is 50-200 nm.

6. The nano-ceramic coating according to claim 1, characterized in that, The dispersant is sodium tripolyphosphate.

7. The nano-ceramic coating according to claim 1, characterized in that, The dispersing solvent contains water, and the amount of water used is 8-15 parts.

8. The method for preparing the medium-to-high temperature resistant and corrosion-resistant nano-ceramic coating according to any one of claims 1 to 7, characterized in that, Includes the following steps: 1) Weigh out nano-alumina, nano-boron nitride, nano-magnesium oxide, nano-zirconia, glass powder, dispersant, borax, sepiolite fiber and mica powder and add them to the ball mill to obtain composite powder; 2) Add silica hydrosol to the obtained composite powder, then add dispersing solvent, stir evenly, and obtain a nano-ceramic coating that is resistant to medium and high temperature corrosion.

9. A method for preparing a nano-ceramic film using the medium-to-high temperature resistant and corrosion-resistant nano-ceramic coating according to any one of claims 1 to 7, characterized in that, Includes the following steps: 1) Clean and roughen the surface of the workpiece; 2) Apply a medium-to-high temperature resistant and corrosion-resistant nano-ceramic coating to the surface of the workpiece treated in step 1), and allow it to dry naturally to form a film; 3) Perform a heat treatment, and after cooling, coat the surface with silica hydrosol and perform a second heat treatment to form the medium- and high-temperature resistant and corrosion-resistant nano-ceramic film on the surface of the workpiece.

10. The method according to claim 9, characterized in that, The heating rate for the first heat treatment is 2-4℃ / min, and the holding time is 3-5h; the heating rate for the second heat treatment is 2-4℃ / min, and the holding time is 1-3h.

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