CN111519173A

CN111519173A - Heat-resistant wear-resistant corrosion-resistant zeolite coating on surface of steel mold and preparation method thereof

Info

Publication number: CN111519173A
Application number: CN202010402655.7A
Authority: CN
Inventors: 陈明安; 陈虹玮; 陈永桂
Original assignee: Central South University
Current assignee: Central South University
Priority date: 2020-05-13
Filing date: 2020-05-13
Publication date: 2020-08-11
Anticipated expiration: 2040-05-13
Also published as: CN111519173B

Abstract

The invention discloses a preparation method of a heat-resistant, wear-resistant and corrosion-resistant zeolite coating on the surface of a steel mold, which comprises the steps of firstly adopting a first hydrothermal pre-synthesis to deposit a silica gel thin layer and small-particle zeolite on the surface of the steel mold, then adopting a second hydrothermal synthesis to continuously deposit the silica gel layer and promote the small-particle zeolite to grow, forming new small-particle zeolite in the second hydrothermal synthesis process to fill between the grown zeolite particles, alternately growing and stacking to form a continuous and compact zeolite particle film layer with different size and size particle zeolite grades, and forming the zeolite coating by the stacked silica gel layer and the zeolite particle film layer. According to the invention, a layer of zeolite coating with a compact structure, heat resistance, wear resistance and corrosion resistance can be finally generated on the surface of the steel mould through secondary hydrothermal synthesis, so that the service life of the mould is effectively prolonged.

Description

Heat-resistant wear-resistant corrosion-resistant zeolite coating on surface of steel mold and preparation method thereof

Technical Field

The invention relates to a heat-resistant, wear-resistant and corrosion-resistant zeolite coating on the surface of a steel die and a preparation method thereof, belonging to the technical field of steel die manufacturing.

Background

In die casting, extrusion, forging, drawing, stamping, and plastic product forming processes, various die steels are widely used to make dies and die parts, such as H13, 3Cr2W8V, 5CrNiMo, 4CrW2Si, Cr12MoV, T8A, T10A, 4Cr5Mo2MnVSi, and the like. The service condition of the die steel is severe, the interaction between the workpiece and the die causes the stress condition of the inner surface of the die to be very complex, and the die can lose efficacy due to deformation, fatigue crack of the inner surface and the like. The surface of the die bears the abrasion caused by the high-pressure friction action of the blank in the processing processes of extrusion, drawing, forging, stamping and the like, and the die is softened at higher processing temperature during extrusion, drawing and forging, so that the hardness and the wear resistance of the inner surface of the die are reduced, and the abrasion of the die is aggravated. The die-casting die is in direct contact with high-temperature molten metal, deformation is easy to occur to influence the precision of the die-casting die, and the aluminum alloy melt with more active chemical properties can also corrode the inner surface of the die. When plastic products such as polyvinyl chloride and polyethylene are molded, corrosive gases such as hydrogen chloride and hydrogen fluoride, which are highly corrosive to molds, are released from molten raw materials.

In order to prolong the service life of the die, the surface of the die is required to have high hardness, heat resistance, wear resistance, corrosion resistance and the like, and various surface treatment methods are proposed. The main surface treatment methods at present are: (1) surface modification techniques including surface thermal diffusion treatment, surface phase change strengthening and the like, such as diffusion treatment of carbon, nitrogen, boron, carbon/nitrogen, oxygen/nitrogen, sulfur/carbon/nitrogen and the like, carbon/nitrogen/titanium ion implantation and the like; (2) various surface coating plating techniques, such as surface chromium plating, nickel, physical (chemical) vapor deposition, arc ion plating and magnetron sputtering hard coating such as TiN, CrN, TiAlN, etc. The surface treatment methods are widely applied in industry, but the technical problems of mold manufacturing and mold service life are solved, for example, the mold deformation can be caused by the high temperature of about 500 ℃ widely adopted by diffusion treatment of carbon, nitrogen and the like, the injection depth of carbon/nitrogen/titanium ions is small, and the better surface wear-resistant and corrosion-resistant performance is expected; the body toughness of the coatings coated with chromium, nickel, TiN, CrN, TiAlN and the like on the surface is poor, and the interface bonding strength between the coatings and the surface of the die is low.

Zeolites are inorganic salt materials composed of hydrated silicate crystals having a periodic pore structure, and are interconnected by oxygen atoms sharing the tips of tetrahedrons to form a three-dimensional framework having a specific pore structure orientation. Due to the excellent characteristics of separation, corrosion resistance, antibiosis and the like, researchers at home and abroad propose various synthetic preparation methods of the zeolite film, such as a direct hydrothermal synthesis method, a seed crystal method, a microwave heating synthesis method and the like. The zeolite film has good corrosion resistance, and researchers prepare compact zeolite films which are tightly combined with a matrix on various metal matrixes such as aluminum alloy, titanium alloy, stainless steel and the like. The test result shows that the zeolite film can reduce the damage effect of corrosive media such as acid, alkali, salt water and the like on the metal matrix, the corrosion current density of the metal matrix protected by the zeolite film in various test electrolytes is reduced by 2-5 orders of magnitude, and the low-frequency impedance can be improved by 3-5 orders of magnitude, which shows that the zeolite film can effectively protect the coated metal matrix. The results of the abrasion comparison tests of the anodic oxidation coating and the zeolite coating on the surface of the 2024-T3 aluminum alloy by researchers show that the abrasion rate of the anodic oxidation coating is 26 mu m/h, while the abrasion rate of the zeolite coating is only 6.5 mu m/h, and the abrasion rate of the zeolite coating is only 1/4 of the former, which indicates that the zeolite coating has excellent abrasion resistance. The research result shows that the zeolite film layer synthesized on the stainless steel substrate in the high-temperature test environment has stable performance and good bonding strength between the zeolite and the substrate.

However, in the process of direct hydrothermal synthesis of the zeolite coating on the surface of the steel mold, the alkaline synthetic solution easily causes pitting corrosion on the surface of the steel mold, and if the pitting corrosion depth is large and the area is large, the defects of holes and the like of the gel layer in the places are caused, and finally the gel layer of the zeolite coating is not dense and continuous, the heat resistance, wear resistance and corrosion resistance of the zeolite coating are affected, and the service life of the steel mold is further affected.

Disclosure of Invention

In order to overcome the defects in the process of directly synthesizing the zeolite coating by the hydrothermal method, the invention aims to provide the zeolite coating which is uniform and compact on the surface of the steel mold, heat-resistant, wear-resistant and corrosion-resistant and the preparation method thereof, so as to improve the heat-resistant, wear-resistant and corrosion-resistant performances of the steel mold and prolong the service life of the steel mold.

In order to achieve the technical purpose, the invention adopts the following technical scheme:

a method for preparing a heat-resistant, wear-resistant and corrosion-resistant zeolite coating on the surface of a steel mold comprises the steps of firstly adopting a first hydrothermal pre-synthesis to deposit a silica gel thin layer and small-particle zeolite on the surface of the steel mold, then adopting a second hydrothermal synthesis to continuously deposit the silica gel layer and promote the small-particle zeolite to grow, forming new small-particle zeolite in the second hydrothermal synthesis process to fill between the grown zeolite particles, alternately growing and stacking to form a continuous compact zeolite particle film layer with different size and size particle zeolite grades, and forming the zeolite coating by the stacked silica gel layer and the zeolite particle film layer.

The invention adopts the secondary hydrothermal synthesis to prepare the heat-resistant, wear-resistant and corrosion-resistant zeolite coating on the surface of the steel mould. When the first hydrothermal pre-synthesis is carried out, NaOH with relatively low concentration is adopted, so that the corrosion degree of the alkaline synthetic solution to the surface of the steel mold can be reduced; meanwhile, TPAOH and TEOS with relatively low concentration can reduce the deposition rate and growth speed of zeolite particles on the surface of the steel mold, thus being beneficial to reducing the deposition obstruction of the silica gel layer on the surface of the steel mold and improving the quality of the silica gel layer; and then the temperature and time of the first hydrothermal pre-synthesis are cooperatively controlled, so that a thin silica gel layer with few defects can be deposited on the surface of the steel mould, and the small-particle zeolite is formed. During the second hydrothermal synthesis, the corrosion resistance of the surface of the steel mold is improved after the first hydrothermal pre-synthesis, the damage effect on the surface of the steel mold is reduced by adopting the NaOH with relatively high concentration, and the nucleation rate and the growth rate of the small-particle zeolite on the surface of the steel mold subjected to the first hydrothermal pre-synthesis can be improved by cooperating with the TPAOH and the TEOS with relatively high concentration, relatively long synthesis time and relatively high synthesis temperature, so that the zeolite film-forming quality is improved. The secondary surface deposition of the silica gel at the initial stage of the second hydrothermal synthesis not only repairs the defects in the silica gel thin layer formed by the first hydrothermal synthesis, but also promotes the preferential growth of the small-particle zeolite under the synergistic effect with the small-particle zeolite formed by the first hydrothermal synthesis, and the new small-particle zeolite formed in the second hydrothermal synthesis process is filled among the grown zeolite particles, and the new small-particle zeolite alternately grows and stacks to form a continuous compact zeolite particle film layer graded by zeolite particles with different sizes, so that the new zeolite coating is formed by the silica gel layer, and the compactness and the wear-resistant and corrosion-resistant properties of the zeolite coating are further improved.

It should be noted that, in the present invention, the relatively low concentration, the relatively high concentration, the relatively short time, the relatively long time, the relatively low temperature and the relatively high temperature all refer to the relative values of the concentration, the time and the temperature in the first hydrothermal pre-synthesis process and the second hydrothermal synthesis process.

Preferably, the steel mold material is hot, warm and cold die steel of various types such as H13, 3Cr2W8V, 5CrNiMo, 4CrW2Si, Cr12MoV, T8A, T10A, 4Cr5Mo2MnVSi, etc., which are die cast, extruded, forged, drawn, stamped and formed plastic products.

Preferably, the surface of the steel mold is firstly polished, treated by acid/alkali liquor and washed by deionized water so as to remove impurities and oil stains on the surface.

Preferably, the synthesis solution used in the first hydrothermal pre-synthesis is prepared by: tetrapropylammonium hydroxide, tetraethyl silicate, sodium hydroxide and deionized water are mixed according to the molar ratio of TPAOH, TEOS, NaOH and H₂O ═ 0.1 to 0.2: (0.4-1): (0.3-0.5): 100 mixing and stirring for 3-15 h.

Preferably, the temperature of the first hydrothermal pre-synthesis is 150-190 ℃ and the time is 1-6 h. The inventor finds that when the temperature of the first hydrothermal pre-synthesis is lower, the number of zeolite particles covered on the surface of a steel mould is less, and the final zeolite particle film layer cannot achieve the synergistic optimization effect of zeolite particles with different size grades; when the temperature of the first hydrothermal pre-synthesis is higher, the corrosion damage effect of the alkaline synthetic solution on the surface of the steel mould is aggravated, and the defects cannot be completely repaired even after the second hydrothermal synthesis, so that the silica gel layer of the zeolite coating is not compact and continuous. When the time of the first hydrothermal pre-synthesis is too short, a large amount of zeolite particles with extremely small sizes can be formed on the surface of the steel mould, even if the sizes of the zeolite particles in the zeolite particle film layer formed by the interactive growth after the second hydrothermal synthesis are equivalent, the sizes of the particles are not in a grading relationship, so that the compactness and the wear resistance of the zeolite particle film layer are reduced; when the time of the first hydrothermal pre-synthesis is too long, zeolite particles grow seriously and cover the surface of the steel mold, so that the defect of the first hydrothermal pre-synthesized silica gel thin layer cannot be repaired by the second hydrothermal synthesis, and the corrosion resistance of the zeolite coating is reduced.

Preferably, the synthetic fluid used in the second hydrothermal synthesis is prepared by: tetrapropylammonium hydroxide, tetraethyl silicate, sodium hydroxide and deionized water are mixed according to the molar ratio of TPAOH, TEOS, NaOH and H₂O ═ 0.16 to 0.35: (0.7-1.5): (0.6-1): 100 mixing and stirring for 3-15 h.

Preferably, the temperature of the second hydrothermal synthesis is 170-220 ℃, and the time is 8-38 h.

The invention also provides the heat-resistant wear-resistant corrosion-resistant zeolite coating prepared by the preparation method, and the zeolite coating comprises a two-layer structure, wherein the first layer is a silica gel layer on the surface of the steel mold, and the second layer is a zeolite particle film layer on the silica gel layer.

Preferably, the thickness of the zeolite coating is 1.5-45 μm, wherein the thickness of the silica gel layer is 0.5-5 μm, and the thickness of the zeolite particle film layer is 1-40 μm.

The invention adopts a secondary hydrothermal synthesis method to prepare the zeolite coating on the surface of the steel mould so as to improve the heat resistance, wear resistance and corrosion resistance of the surface of the mould. Firstly, a layer of silica gel thin layer and a large amount of small-particle zeolite are formed on the surface of a die by adopting first hydrothermal pre-synthesis of synthetic fluid with relatively short time, low temperature and low concentration, so that the corrosion effect of the relatively high-concentration synthetic fluid on the surface of a steel die in the second hydrothermal synthesis process is reduced, and the small-particle zeolite can promote the formation of a zeolite particle film layer in the second hydrothermal synthesis process; the deposition of the silica gel layer at the initial stage of the second hydrothermal synthesis increases the thickness of the silica gel layer on the surface of the steel mould, can repair the defects in the silica gel film formed by the first hydrothermal synthesis, and can promote the preferential growth of the small-particle zeolite under the synergistic effect with the small-particle zeolite formed by the first hydrothermal synthesis. The invention can finally generate a layer of zeolite coating with compact structure, heat resistance, wear resistance and corrosion resistance on the surface of the steel mould through the secondary hydrothermal synthesis, thereby effectively prolonging the service life of the mould.

The invention has the advantages that:

(1) the synthesis temperature adopted by the secondary hydrothermal synthesis method is lower (150-220 ℃), the influence on the mechanical properties of the steel mould such as strength, hardness and the like is small, and the deformation of the mould is small;

(2) the secondary hydrothermal synthesis method forms a zeolite coating with a double-layer structure on the surface of a steel mould, wherein the zeolite coating is formed by a silica gel layer and continuous compact zeolite particle film layers which are alternately grown and stacked and formed by zeolite particle grading with different sizes, the silica gel layer is continuous, compact and free of defects, and has excellent capacity of retarding transmission of corrosive media, and the silica gel layer can be combined with the zeolite particle film layers which are alternately grown by particles and the surface of the mould through silicon hydroxyl, so that the zeolite coating and the surface of the mould have very good combination strength; and the zeolite particle film layer is formed by filling new small-particle zeolite formed in the second hydrothermal synthesis process into the large zeolite particles of the small-particle zeolite formed in the first hydrothermal pre-synthesis process, and the new small-particle zeolite and the large zeolite particles are alternately grown and stacked to form a continuous compact zeolite particle film layer graded by zeolite particles with different sizes.

In conclusion, the invention can finally generate a layer of zeolite coating with a compact structure, heat resistance, wear resistance and corrosion resistance on the surface of the steel mould through the secondary hydrothermal synthesis, thereby effectively prolonging the service life of the mould.

Drawings

FIG. 1 is a scanning electron micrograph of the surface of the sample after the first hydrothermal pre-synthesis (a is 2h, b is 3h, and c is 4h) in examples 1-3.

As shown in FIG. 1, after hydrothermal pre-synthesis for a relatively short time, a large amount of small-particle zeolite exists on the surface of the sample, and hole defects appear on the surface of the sample, which indicates that the synthetic solution has a certain corrosive damage effect on the surface of the sample.

FIG. 2 is X-ray diffraction patterns of the samples after the first hydrothermal pre-synthesis (

synthesis times

2h, 3h and 4h) and the untreated samples in examples 1-3 (each curve is the first hydrothermal pre-synthesis for 4h, 3h, 2h and the untreated sample from top to bottom).

As shown in FIG. 2, the weak characteristic diffraction peak of the sample after the first hydrothermal pre-synthesis proves the existence of the small-particle zeolite, and the weak diffraction peak indicates that the size of the zeolite particle is small.

FIG. 3 is a scanning electron micrograph of the surface and cross-section of the sample directly after the primary hydrothermal synthesis in comparative example 1.

As shown in fig. 3, the surface map of the sample shows that the sizes of the zeolite particles are substantially consistent, and the phenomenon of grading of the zeolite particles with different sizes does not occur; the cross-sectional view of the sample shows that corrosion of the sample occurs at the junction of the zeolite coating and the sample, which also results in defects in the silica gel layer, making the silica gel layer discontinuous.

FIG. 4 is a scanning electron micrograph of the surface and cross-section of the sample after the second hydrothermal synthesis in examples 1 to 3, wherein a and b are TS-2, c and d are TS-3, and e and f are TS-4.

As shown in fig. 4, the picture of the surface scanning electron microscope shows that the zeolite membrane has a compact structure, the zeolite particles synthesized for the second time after 2h of pre-synthesis have a certain size difference, and the zeolite particles synthesized for the second time after 3h and 4h of pre-synthesis have alternate sizes and present a particle grading relationship; the cross-sectional pictures show that there are no microcracks in the zeolite coating, the coating is continuous, and there is no evidence of corrosion of the sample at the juncture of the zeolite coating and the sample.

FIG. 5 is X-ray diffraction patterns of a sample directly after primary hydrothermal synthesis in comparative example 1 and a sample after secondary hydrothermal synthesis in examples 1 to 3 (each curve is a sample of example 3, example 2, example 1 and comparative example 1 from top to bottom).

As shown in fig. 5, the characteristic diffraction peaks indicate that the sample surfaces were all covered with zeolite particles.

FIG. 6 is a graph showing the polarization curves of an untreated sample, a sample directly after primary hydrothermal synthesis in comparative example 1, and a sample after secondary hydrothermal synthesis in examples 1 to 3 in a 3.5 wt% NaCl solution.

As shown in fig. 6, the polarization curve indicates that the zeolite coating significantly reduced the corrosion current density of the sample. Both the untreated sample and the direct primary hydrothermal synthesis sample in comparative example 1 showed pitting; and the curve in the anode polarization curve of the sample after the secondary hydrothermal synthesis in the embodiment 1-3 is stable, and the pitting phenomenon does not occur.

FIG. 7 is an AC impedance spectrum measured by immersing an untreated sample in a 3.5 wt% NaCl solution for 1 hour.

FIG. 8 is an AC impedance spectrum measured by immersing the sample of the direct primary hydrothermal synthesis in 3.5 wt% NaCl solution for various periods of time in comparative example 1.

FIG. 9 is an AC impedance spectrum measured after soaking a sample in 3.5 wt% NaCl solution for various periods of time after the second hydrothermal synthesis in example 1.

FIG. 10 is the AC impedance spectrum measured after soaking the sample in 3.5 wt% NaCl solution for different times after the second hydrothermal synthesis in example 2.

As shown in FIG. 10, the low frequency impedance of the sample dropped most slowly, and after continuous immersion for 984h, the impedance reached 2.6 × 10⁴Ω·cm²。

FIG. 11 is the AC impedance spectrum measured after soaking the sample in 3.5 wt% NaCl solution for different times after the second hydrothermal synthesis in example 3.

As shown in FIG. 11, the low frequency impedance of the sample after 984h of test can reach 2.4 × 10⁴Ω·cm²Slightly below 3h pretreatment sample.

FIG. 12 is the AC impedance spectrum measured after soaking the sample in 3.5 wt% NaCl solution for different times after the second hydrothermal synthesis in example 4.

As shown in fig. 12, the low frequency impedance of the sample decreases faster, and the low frequency impedance decreases by approximately 1 order of magnitude after soaking for 96 hours, which indicates that the sample has poor corrosion resistance, but is still better than the sample synthesized by direct primary hydrothermal synthesis in comparative example 1.

FIG. 13 is a graph of the macroscopic corrosion of untreated samples, samples directly synthesized in the primary hydrothermal synthesis in comparative example 1, and samples after the secondary hydrothermal synthesis in examples 1-3 in a 3.5 wt% NaCl solution.

As shown in fig. 13, the zeolite coating covered the sample after a prolonged salt water soak at a significantly lower level of corrosion than the untreated sample; the corrosion area of the surface of the sample obtained by the second hydrothermal synthesis is smaller than that of the sample obtained by the first hydrothermal synthesis, the best corrosion resistance is shown after the first hydrothermal synthesis (the synthesis time is 3h) and the second hydrothermal synthesis (the synthesis time is 20h), and no corrosion mark is left on the surface of the sample.

Detailed Description

The invention is further illustrated by the following examples, which are not to be construed as limiting the invention thereto.

Example 1

1. Sample surface cleaning

The H13 die steel was sanded and then rinsed with aqueous nitric acid and deionized water.

2. Preparation of pretreatment synthetic solution

According to the molar ratio of TPAOH to TEOS to NaOH to H₂O ═ 0.15: 0.5: 0.45: 100, respectively weighing tetrapropylammonium hydroxide, tetraethyl silicate, sodium hydroxide and deionized water, and mixing and stirring for 6 hours at room temperature.

3. First hydrothermal pre-synthesis

Pouring the uniformly mixed synthetic solution into a reaction kettle containing a sample, carrying out hydrothermal synthesis at 175 ℃ for 2h, taking out, washing the deionized water sample for 2 times, and drying for later use.

4. Second hydrothermal synthesis solution preparation

According to the molar ratio of TPAOH to TEOS to NaOH to H₂O ═ 0.21: 0.75: 0.65: 100, respectively weighing tetrapropylammonium hydroxide, tetraethyl silicate, sodium hydroxide and deionized water, and mixing and stirring for 6 hours at room temperature.

5. Second hydrothermal synthesis

And pouring the uniformly mixed synthetic solution into a reaction kettle containing a pretreated sample, carrying out hydrothermal synthesis at 180 ℃ for 20 hours, taking out, washing with deionized water for 2 times, and drying to obtain TS-2.

Example 2

1. Sample surface cleaning

2. Preparation of pretreatment synthetic solution

3. First hydrothermal pre-synthesis

Pouring the uniformly mixed synthetic solution into a reaction kettle containing a sample, carrying out hydrothermal synthesis at 175 ℃ for 3h, taking out, washing the deionized water sample for 2 times, and drying for later use.

4. Second hydrothermal synthesis solution preparation

5. Second hydrothermal synthesis

And carrying out hydro-thermal synthesis on the pretreated sample at 180 ℃ for 20h, taking out, washing with deionized water for 2 times, and drying to obtain TS-3.

Example 3

1. Sample surface cleaning

2. Preparation of pretreatment synthetic solution

3. First hydrothermal pre-synthesis

Pouring the uniformly mixed synthetic solution into a reaction kettle containing a sample, carrying out hydrothermal synthesis at 175 ℃ for 4h, taking out, washing the deionized water sample for 2 times, and drying for later use.

4. Second hydrothermal synthesis solution preparation

5. Second hydrothermal synthesis

And carrying out hydro-thermal synthesis on the pretreated sample at 180 ℃ for 20h, taking out, washing with deionized water for 2 times, and drying to obtain TS-4.

Example 4

1. Sample surface cleaning

2. Preparation of pretreatment synthetic solution

3. First hydrothermal pre-synthesis

Pouring the uniformly mixed synthetic solution into a reaction kettle containing a sample, carrying out hydrothermal synthesis at 175 ℃ for 5h, taking out, washing the deionized water sample for 2 times, and drying for later use.

4. Preparation of secondary hydrothermal synthetic solution

5. Second hydrothermal synthesis

And carrying out hydro-thermal synthesis on the pretreated sample at 180 ℃ for 20h, taking out, washing with deionized water for 2 times, and drying to obtain TS-5.

Example 5

1. Sample surface cleaning

The 3Cr2W8V die steel was sanded and then washed with aqueous nitric acid and deionized water.

2. Preparation of pretreatment synthetic solution

3. First hydrothermal pre-synthesis

4. Second hydrothermal synthesis solution preparation

5. Second hydrothermal synthesis

And carrying out hydro-thermal synthesis on the pretreated sample at 180 ℃ for 20h, taking out, washing for 2 times by using deionized water, and drying.

Example 6

1. Sample surface cleaning

5CrNiMo die steel is polished by sand paper and then washed by nitric acid water solution and deionized water.

2. Preparation of pretreatment synthetic solution

According to the molar ratio of TPAOH to TEOS to NaOH to H₂O ═ 0.15: 0.6: 0.4: 100, respectively weighing tetrapropylammonium hydroxide, tetraethyl silicate, sodium hydroxide and deionized water, and mixing and stirring for 6 hours at room temperature.

3. First hydrothermal pre-synthesis

4. Second hydrothermal synthesis solution preparation

According to the molar ratio of TPAOH to TEOS to NaOH to H₂O ═ 0.25: 0.8: 0.65: 100, respectively weighing tetrapropylammonium hydroxide, tetraethyl silicate, sodium hydroxide and deionized water, and mixing and stirring for 6 hours at room temperature.

5. Second hydrothermal synthesis

Comparative example 1

1. Sample surface cleaning

2. Preparation of hydrothermal synthesis solution

3. Direct one-time hydrothermal synthesis

And pouring the uniformly mixed synthetic solution into a reaction kettle containing a sample, carrying out hydrothermal synthesis at 175 ℃ for 24h, taking out the synthetic solution, washing the sample with deionized water for 2 times, and drying to obtain S-24.

Claims

1. A preparation method of a heat-resistant, wear-resistant and corrosion-resistant zeolite coating on the surface of a steel mold is characterized by comprising the following steps: firstly, a silica gel thin layer and small-particle zeolite are deposited on the surface of a steel mould through first hydrothermal pre-synthesis, then the silica gel layer is continuously deposited through second hydrothermal synthesis, the small-particle zeolite is promoted to grow, new small-particle zeolite is formed in the second hydrothermal synthesis process and filled among the grown zeolite particles, the zeolite particles are alternately grown and stacked to form a continuous compact zeolite particle film layer with different size and size particle zeolite grading, and the laminated silica gel layer and the zeolite particle film layer form a zeolite coating.

2. The method for preparing the heat-resistant wear-resistant corrosion-resistant zeolite coating on the surface of the steel die as claimed in claim 1, wherein the method comprises the following steps: the steel die material is hot-working, warm-working or cold-working die steel of various types which is manufactured by die casting, extruding, forging, drawing, stamping and plastic product forming.

3. The method for preparing the heat-resistant wear-resistant corrosion-resistant zeolite coating on the surface of the steel die as claimed in claim 1, wherein the method comprises the following steps: the surface of the steel mould is firstly polished, treated by acid/alkali liquor and washed by deionized water so as to remove impurities and oil stains on the surface.

4. The method for preparing the heat-resistant wear-resistant corrosion-resistant zeolite coating on the surface of the steel die as claimed in claim 1, wherein the method comprises the following steps: the preparation of the synthetic solution adopted by the first hydrothermal pre-synthesis is as follows: tetrapropylammonium hydroxide and silicic acid tetraThe molar ratio of the ethyl ester to the sodium hydroxide to the deionized water is TPAOH to TEOS to NaOH to H₂O ═ 0.1 to 0.2: (0.4-1): (0.3-0.5): 100 mixing and stirring for 3-15 h.

5. The method for preparing the heat-resistant wear-resistant corrosion-resistant zeolite coating on the surface of the steel die as claimed in claim 1, wherein the method comprises the following steps: the temperature of the first hydrothermal pre-synthesis is 150-190 ℃, and the time is 1-6 h.

6. The method for preparing the heat-resistant wear-resistant corrosion-resistant zeolite coating on the surface of the steel die as claimed in claim 1, wherein the method comprises the following steps: the preparation of the synthetic fluid adopted by the second hydrothermal synthesis is as follows: tetrapropylammonium hydroxide, tetraethyl silicate, sodium hydroxide and deionized water are mixed according to the molar ratio of TPAOH, TEOS, NaOH and H₂O ═ 0.16 to 0.35: (0.7-1.5): (0.6-1): 100 mixing and stirring for 3-15 h.

7. The method for preparing the heat-resistant wear-resistant corrosion-resistant zeolite coating on the surface of the steel die as claimed in claim 1, wherein the method comprises the following steps: the temperature of the second hydrothermal synthesis is 170-220 ℃, and the time is 8-38 h.

8. The heat-resistant wear-resistant corrosion-resistant zeolite coating prepared by the preparation method of any one of claims 1 to 7 is characterized in that: the zeolite coating comprises a two-layer structure, wherein the first layer is a silica gel layer on the surface of the steel mould, and the second layer is a zeolite particle film layer on the silica gel layer.

9. The zeolite coating of claim 8, characterized by: the thickness of the zeolite coating is 1.5-45 mu m, the thickness of the silica gel layer is 0.5-5 mu m, and the thickness of the zeolite particle film layer is 1-40 mu m.