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

Abstract

The invention discloses a method for preparing a heat-resistant, wear-resistant and corrosion-resistant zeolite coating on the surface of a steel mold. First, a first hydrothermal pre-synthesis is used to deposit a thin layer of silica gel and small particle zeolite on the surface of a steel mold, and then a second The second hydrothermal synthesis continues to deposit the silica gel layer, and at the same time promotes the growth of small-particle zeolite, and during the second hydrothermal synthesis, new small-particle zeolite is formed to fill between the grown zeolite particles, and grow and stack alternately, forming a structure composed of small particles. The continuous and dense zeolite particle membrane layers with zeolite particle gradation of different sizes, the stacked silica gel layer and the zeolite particle membrane layer form a zeolite coating. The invention can finally generate a layer of zeolite coating with dense structure, heat resistance, wear resistance and corrosion resistance on the surface of the steel mold through secondary hydrothermal synthesis, thereby effectively improving the service life of the mold.

Description

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

technical field

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

Background technique

In die casting, extrusion, forging, drawing, stamping and plastic products and other forming processes, various die steels are widely used to make dies and die parts, such as H13, 3Cr2W8V, 5CrNiMo, 4CrW2Si, Cr12MoV, T8A, T10A, 4Cr5Mo2MnVSi, etc. . The service conditions of die steel are poor, and the interaction between the workpiece and the die causes the stress on the inner surface of the die to be very complicated, which will cause the die to fail due to deformation and fatigue cracks on the inner surface. During extrusion, drawing, forging and stamping, the die surface is subject to wear caused by the high pressure friction of the billet, and the higher processing temperature during extrusion, drawing and forging will soften the die, making the inner surface of the die harder and harder. The wear resistance is reduced, and the wear of the mold is aggravated. The die-casting mold is in direct contact with the high-temperature molten metal, which is prone to deformation and affects its accuracy, and the chemically active aluminum alloy melt will also corrode the inner surface of the mold. When plastic products such as polyvinyl chloride and polyethylene are molded, the molten raw materials will release corrosive gases such as hydrogen chloride or hydrogen fluoride, which are seriously corrosive to the mold.

In order to improve the service life of the mold, the mold surface is required to have high hardness, heat resistance, wear resistance, corrosion resistance and other properties, and a variety of surface treatment methods have been proposed. At present, the main surface treatment methods are: (1) Surface modification technology including surface thermal infiltration treatment, surface transformation strengthening and other technologies, such as carbon, nitrogen, boron and carbon/nitrogen, oxygen/nitrogen, sulfur/nitrogen, sulfur / carbon/nitrogen and other diffusion treatment, carbon/nitrogen/titanium ion implantation, etc.; (2) coating techniques for various surface coatings, such as surface chrome plating, nickel, physical (chemical) vapor deposition, arc ion plating and magnetron Sputtering hard coatings such as TiN, CrN, TiAlN, etc. These surface treatment methods have been widely used in industry, but there are still technical problems that restrict mold manufacturing and mold service life. /Nitrogen/Titanium ion implantation depth is small, better surface wear and corrosion resistance is expected; chromium, nickel, TiN, CrN, TiAlN and other coatings coated on the surface have poor body strength and toughness, and the interface between the coating and the mold surface The binding strength is low.

Zeolite is a kind of inorganic salt material composed of hydrated silica (aluminum) salt crystals with periodic pore structure. The oxygen atoms at the top of the shared tetrahedron are connected to each other to form a three-dimensional space framework with a specific pore structure direction. Due to its excellent properties such as separation, corrosion resistance and antibacterial, researchers at home and abroad have proposed a variety of synthetic preparation methods for zeolite films, such as direct hydrothermal synthesis, seeding method, and microwave heating synthesis. Zeolite films have good corrosion resistance, and researchers have prepared dense and tightly bound zeolite films on various metal substrates such as aluminum alloys, titanium alloys, and stainless steel. The test results show that the zeolite film can reduce the damage effect of corrosive media such as acid, alkali and salt water on the metal matrix. The increase is 3 to 5 orders of magnitude, which indicates that the zeolite film can effectively protect the coated metal substrate. Some researchers conducted a wear comparison test of the anodized coating on the surface of the 2024-T3 aluminum alloy with the zeolite coating. The results showed that the wear rate of the anodized coating was 26 μm/h, while the zeolite coating was only 6.5 μm/h. The latter The wear rate is only 1/4 of the former, indicating that the zeolite coating has superior wear resistance. Some research results show that the zeolite membrane layer synthesized on the stainless steel substrate under the high temperature test environment has stable performance and good bonding strength between the zeolite and the substrate.

However, in the process of directly hydrothermally synthesizing zeolite coating on the surface of the steel mold, the alkaline synthesis solution will easily lead to pitting corrosion on the surface of the steel mold. Defects eventually lead to the non-dense and continuous gel layer of the zeolite coating, which affects the heat-resistant, wear-resistant and corrosion-resistant properties of the zeolite coating, which in turn affects the service life of the steel mold.

SUMMARY OF THE INVENTION

In order to solve the defects existing in the process of direct hydrothermal synthesis of zeolite coating, the purpose of the present invention is to provide a zeolite coating with uniform, compact, heat-resistant, wear-resistant and corrosion-resistant surface of a steel mold and a preparation method thereof, so as to improve the resistance to steel molds. Thermal wear and corrosion resistance, improve the service life of steel molds.

In order to realize above-mentioned technical purpose, the present invention adopts following technical scheme:

A method for preparing a heat-resistant, wear-resistant, and corrosion-resistant zeolite coating on the surface of a steel mold. First, the first hydrothermal pre-synthesis is used to deposit a thin layer of silica gel and small particle zeolite on the surface of the steel mold, and then the second hydrothermal synthesis is used. Continue to deposit the silica gel layer, while promoting the growth of small zeolite, and in the second hydrothermal synthesis process, new small zeolite is formed to fill between the grown zeolite particles, grow and stack alternately, forming particles of different sizes. The continuous dense zeolite particle membrane layer of zeolite gradation, the laminated silica gel layer and the zeolite particle membrane layer form a zeolite coating.

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 mold. In the first hydrothermal pre-synthesis, the use of relatively low concentration of NaOH can reduce the corrosion degree of the alkaline synthesis solution on the surface of the steel mold; at the same time, the use of relatively low concentrations of TPAOH and TEOS can reduce the deposition rate of zeolite particles on the surface of the steel mold and growth rate, which is conducive to reducing the deposition barrier of the silicon gel layer on the surface of the steel mold and improving the quality of the silicon gel layer; and by controlling the temperature and time of the first hydrothermal pre-synthesis, a layer of silicon gel can be deposited on the surface of the steel mold. A thinner layer of silica gel with fewer defects, and the formation of small particle zeolite. During the second hydrothermal synthesis, since the corrosion resistance of the steel mold surface was improved after the first hydrothermal pre-synthesis, the relatively high concentration of NaOH was used to reduce the damage to the surface of the steel mold, synergistic with the relatively high concentration of TPAOH And TEOS, as well as relatively long synthesis time and relatively high synthesis temperature, can improve the nucleation rate and growth rate of small particle zeolite on the surface of the steel mold after the first hydrothermal pre-synthesis, thereby improving the quality of zeolite film formation. The re-surface deposition of silica gel in the initial stage of the second hydrothermal synthesis not only repairs the defects in the thin layer of silica gel formed by the first hydrothermal pre-synthesis, but also is compatible with the small particles formed by the first hydrothermal pre-synthesis. The synergistic effect of zeolite promotes the preferential growth of these small zeolites, and the new small zeolites formed during the second hydrothermal synthesis are filled between the grown zeolite particles, and they alternately grow and stack to form zeolites of different sizes. The continuous and dense zeolite particle membrane layer with particle gradation and the silica gel layer form a new zeolite coating, which further improves the density of the zeolite coating and its wear resistance and corrosion resistance.

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

Preferably, the steel mold material is various types of hot work, warm work and cold work die steels of die casting, extrusion, forging, drawing, stamping and plastic product forming, such as H13, 3Cr2W8V, 5CrNiMo, 4CrW2Si , Cr12MoV, T8A, T10A, 4Cr5Mo2MnVSi, etc.

Preferably, the surface of the steel mold is first polished, treated with acid/lye, and cleaned with deionized water to remove surface impurities and oil stains.

Preferably, the preparation of the synthetic liquid adopted in the first hydrothermal pre-synthesis is: the molar ratio of tetrapropylammonium hydroxide, tetraethyl silicate, sodium hydroxide and deionized water is TPAOH:TEOS:NaOH:H ₂ O=(0.1～0.2): (0.4～1): (0.3～0.5): 100 Mix and stir for 3～15h.

Preferably, the temperature of the first hydrothermal pre-synthesis is 150-190° C., and the time is 1-6 h. The inventor found that when the first hydrothermal pre-synthesis temperature is low, the number of zeolite particles covered on the surface of the steel mold will be less, resulting in the final zeolite particle membrane layer unable to achieve the synergistic optimization effect of zeolite particles with different size gradations. When the temperature of the first hydrothermal pre-synthesis is high, it will aggravate the corrosion and damage effect of the alkaline synthesis solution on the surface of the steel mold. Even after the second hydrothermal synthesis, these defects cannot be completely repaired, which eventually leads to the zeolite coating The layer of silicone gel is not dense and continuous. When the first hydrothermal pre-synthesis time is too short, only a large number of extremely small-sized zeolite particles can be formed on the surface of the steel mold. The size of the particles is similar, and the particle size is not in a gradation relationship, which leads to a decrease in the density and wear resistance of the zeolite particle membrane layer; however, when the first hydrothermal pre-synthesis time is too long, the zeolite particles will have grown severely and interacted with each other. If the surface of the steel mold is basically covered, the second hydrothermal synthesis cannot repair the defects of the first hydrothermal pre-synthesized silica gel thin layer, resulting in a decrease in the corrosion resistance of the zeolite coating.

As preferably, the preparation of the synthetic liquid adopted in the second hydrothermal synthesis is: the molar ratio of tetrapropyl ammonium hydroxide, tetraethyl silicate, sodium hydroxide and deionized water is TPAOH:TEOS:NaOH:H ₂ O=(0.16～0.35): (0.7～1.5): (0.6～1): 100 Mix and stir for 3～15h.

Preferably, the temperature of the second hydrothermal synthesis is 170-220° C., and the time is 8-38 hours.

The present invention also provides a heat-resistant, wear-resistant, and corrosion-resistant zeolite coating prepared by the above preparation method. The zeolite coating includes a two-layer structure. The first layer is a silica gel layer on the surface of the steel mold, and the second layer is a silica gel layer. A membrane layer of zeolite particles on an adhesive 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 membrane layer is 1-40 μm.

The invention improves the heat resistance, wear resistance and corrosion resistance of the mold surface by adopting the secondary hydrothermal synthesis method to prepare the zeolite coating on the surface of the steel mold. First, the first hydrothermal pre-synthesis using a relatively short time, low temperature and low concentration of synthesis liquid forms a thin layer of silica gel and a large number of small particle zeolite on the surface of the mold, which reduces the relative relative humidity in the second hydrothermal synthesis process. The corrosion effect of high-concentration synthesis liquid on the surface of steel mold, small particle zeolite can promote the formation of zeolite particle film layer during the second hydrothermal synthesis; The thickness of the silica gel layer on the surface can repair the defects in the silica gel film formed by the first hydrothermal pre-synthesis, and also synergize with the small-particle zeolite formed by the first hydrothermal pre-synthesis to promote the formation of these small-particle zeolites. Preferential growth, and new small zeolite particles formed in the second hydrothermal synthesis process are filled between the grown zeolite particles, and they alternately grow and stack to form continuous dense zeolite particles composed of zeolite particles of different sizes The membrane layer, together with the silica gel layer, constitutes a new zeolite coating. The invention can finally generate a layer of zeolite coating with dense structure, heat resistance, wear resistance and corrosion resistance on the surface of the steel mold through secondary hydrothermal synthesis, thereby effectively improving the service life of the mold.

The advantages of the present invention are:

(1) The synthesis temperature adopted by the secondary hydrothermal synthesis method of the present invention is all relatively low (150-220° C.), and has little influence on the mechanical properties such as the strength and hardness of the steel mold, and the resulting mold deformation is small;

(2) The secondary hydrothermal synthesis method of the present invention forms on the surface of the steel mold a bilayer structure consisting of a silica gel layer and a continuous and dense zeolite particle membrane layer composed of zeolite particle gradations of different sizes and stacked by alternating growth. The zeolite coating, in which the silica gel layer is continuous, dense and defect-free, has excellent ability to block the transmission of corrosive media, and the silica gel layer can interact with the zeolite particle membrane layer of the particles through the silanol group, and can also interact with the particles. The interface bonding between the mold surfaces makes the zeolite coating and the mold surface have very good bonding strength; and the zeolite particle film layer is filled with new small particle zeolite formed in the second hydrothermal synthesis process. The small zeolite particles formed by the sub-hydrothermal pre-synthesis are grown, and the zeolite particles grow and stack alternately to form a continuous and dense zeolite particle film layer composed of zeolite particles of different sizes.

All in all, the present invention can finally generate a layer of zeolite coating with dense structure, heat resistance, wear resistance and corrosion resistance on the surface of the steel mold through secondary hydrothermal synthesis, thereby effectively improving the service life of the mold.

Description of drawings

1 is a scanning electron microscope image 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 Figure 1, after a relatively short period of hydrothermal pre-synthesis, there are a large number of small particles of zeolite on the surface of the sample, and hole defects appear on the surface of the sample, indicating that the synthesis solution has a certain corrosion and damage effect on the surface of the sample.

Fig. 2 is the X-ray diffraction pattern of the sample and the untreated sample after the first hydrothermal pre-synthesis (synthesis time 2h, 3h and 4h) in Example 1-3 (each curve from top to bottom is the first hydrothermal pre-synthesized 4h, 3h, 2h and untreated samples).

As shown in Figure 2, the weak characteristic diffraction peaks of the samples after the first hydrothermal pre-synthesis prove the existence of small particle zeolite, and the weak diffraction peaks indicate that the zeolite particles are small in size.

FIG. 3 is a scanning electron microscope image of the surface and cross-section of the sample after direct one-step hydrothermal synthesis in Comparative Example 1. FIG.

As shown in Figure 3, the sample surface diagram shows that the size of zeolite particles is basically the same, and there is no gradation of zeolite particles of different sizes; the cross-section diagram of the sample shows that the corrosion phenomenon of the sample occurs at the combination of the zeolite coating and the sample , which also leads to defects in the silicone gel layer, making the silicone gel layer discontinuous.

Fig. 4 is the surface and cross-sectional SEM images of the samples after secondary hydrothermal synthesis in Examples 1-3, wherein a and b are TS-2, c and d are TS-3, and e and f are TS-4.

As shown in Figure 4, the surface scanning electron microscope image shows that the zeolite membrane structure is dense, and there is a certain size difference between the surface zeolite particles after 2h pre-synthesis and the second synthesis of surface zeolite particles. The particle sizes are alternate, showing a particle gradation relationship; the cross-sectional pictures show that there are no microcracks in the zeolite coating, the coating is continuous, and there is no sign of corrosion of the sample at the junction of the zeolite coating and the sample.

Figure 5 is the X-ray diffraction pattern of the sample after the first hydrothermal synthesis in Comparative Example 1 and the sample after the second hydrothermal synthesis in Examples 1-3 (each curve from top to bottom is Example 3, Example 2, Example 1 and Comparative Example 1 samples).

As shown in Figure 5, the characteristic diffraction peaks indicate that the surface of the sample is covered by zeolite particles.

6 is a graph of polarization curves of untreated samples, samples after direct hydrothermal synthesis in Comparative Example 1, and samples after secondary hydrothermal synthesis in Examples 1-3 in 3.5 wt% NaCl solution.

As shown in Figure 6, the polarization curves indicate that the zeolite coating significantly reduces the corrosion current density of the samples. Pitting corrosion occurs in the untreated sample and the directly hydrothermally synthesized sample in Comparative Example 1; while the anodic polarization curve of the sample after secondary hydrothermal synthesis in Examples 1-3 is stable and no pitting occurs.

Figure 7 is the AC impedance spectrum measured by soaking the untreated sample in 3.5wt% NaCl solution for 1 h.

FIG. 8 is the AC impedance spectrum measured by the direct one-time hydrothermal synthesis sample soaked in 3.5wt% NaCl solution for different time in Comparative Example 1. FIG.

FIG. 9 is the AC impedance spectrum measured by soaking the sample in 3.5wt% NaCl solution for different time after the secondary hydrothermal synthesis in Example 1. FIG.

FIG. 10 is the AC impedance spectrum measured by soaking the sample in 3.5wt% NaCl solution for different time after the secondary hydrothermal synthesis in Example 2.

As shown in Fig. 10, the low-frequency impedance of the sample decreased the slowest, and it still reached 2.6×10 ⁴ Ω·cm ² after continuous immersion for 984 hours.

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

As shown in Figure 11, the low-frequency impedance of the sample can reach 2.4×10 ⁴ Ω·cm ² after 984 hours of testing, which is slightly lower than that of the sample pretreated for 3 hours.

FIG. 12 is the AC impedance spectrum measured by soaking the sample in 3.5wt% NaCl solution for different time after the secondary hydrothermal synthesis in Example 4. FIG.

As shown in Figure 12, the low-frequency impedance of the sample decreased rapidly, and the low-frequency impedance dropped by nearly an order of magnitude after only 96h of immersion, indicating that the sample has poor corrosion resistance, but it is still better than the direct hydrothermal synthesis sample in Comparative Example 1.

13 is a macroscopic corrosion diagram of an untreated sample, a sample directly hydrothermally synthesized in Comparative Example 1, and a sample after secondary hydrothermal synthesis in Examples 1-3 in a 3.5 wt% NaCl solution.

As shown in Fig. 13, the corrosion degree of the samples covered by the zeolite coating is significantly lower than that of the untreated samples after long-term brine immersion; while the corrosion area on the surface of the secondary hydrothermally synthesized samples is smaller than that of the primary hydrothermally synthesized samples. The hydrothermal pre-synthesis (synthesis time of 3h) and the second hydrothermal synthesis (synthesis time of 20h) showed the best corrosion resistance, and there was no corrosion trace on the surface of the sample.

Detailed ways

The present invention is further described below in conjunction with the embodiments, rather than limiting the invention.

Example 1

1. Sample surface cleaning

H13 die steel is sanded and then cleaned with aqueous nitric acid and deionized water.

2. Preparation of Pretreatment Synthesis Solution

Weigh tetrapropylammonium hydroxide, tetraethyl silicate, sodium hydroxide and deionized water in a molar ratio of TPAOH:TEOS:NaOH:H ₂ O=0.15:0.5:0.45:100, and mix and stir at room temperature for 6 hours.

3. The first hydrothermal pre-synthesis

The homogeneously mixed synthesis solution was poured into the reaction kettle with the samples, and hydrothermally synthesized at 175 °C for 2 h. After taking out, the samples were washed twice with deionized water and dried for later use.

4. The second hydrothermal synthesis solution preparation

Weigh tetrapropyl ammonium hydroxide, tetraethyl silicate, sodium hydroxide and deionized water in a molar ratio of TPAOH:TEOS:NaOH:H ₂ O=0.21:0.75:0.65:100, and mix and stir at room temperature for 6 hours.

5. Second Hydrothermal Synthesis

The evenly mixed synthesis solution was poured into the reaction kettle with the pretreated samples, and hydrothermally synthesized at 180 °C for 20 h. After taking it out, it was washed twice with deionized water and dried, and recorded as TS-2.

Example 2

1. Sample surface cleaning

H13 die steel is sanded and then cleaned with aqueous nitric acid and deionized water.

2. Preparation of Pretreatment Synthesis Solution

Weigh tetrapropylammonium hydroxide, tetraethyl silicate, sodium hydroxide and deionized water in a molar ratio of TPAOH:TEOS:NaOH:H ₂ O=0.15:0.5:0.45:100, and mix and stir at room temperature for 6 hours.

3. The first hydrothermal pre-synthesis

The homogeneously mixed synthesis solution was poured into the reaction kettle with the samples, and hydrothermally synthesized at 175 °C for 3 h. After taking out, the samples were washed twice with deionized water and dried for later use.

4. The second hydrothermal synthesis solution preparation

Weigh tetrapropyl ammonium hydroxide, tetraethyl silicate, sodium hydroxide and deionized water in a molar ratio of TPAOH:TEOS:NaOH:H ₂ O=0.21:0.75:0.65:100, and mix and stir at room temperature for 6 hours.

5. Second Hydrothermal Synthesis

The pretreated samples were hydrothermally synthesized at 180 °C for 20 h, taken out, washed twice with deionized water, and dried, and recorded as TS-3.

Example 3

1. Sample surface cleaning

H13 die steel is sanded and then cleaned with aqueous nitric acid and deionized water.

2. Preparation of Pretreatment Synthesis Solution

Weigh tetrapropylammonium hydroxide, tetraethyl silicate, sodium hydroxide and deionized water in a molar ratio of TPAOH:TEOS:NaOH:H ₂ O=0.15:0.5:0.45:100, and mix and stir at room temperature for 6 hours.

3. The first hydrothermal pre-synthesis

The homogeneously mixed synthesis solution was poured into the reaction kettle with the samples, and hydrothermally synthesized at 175 °C for 4 hours. After taking out, the samples were washed twice with deionized water and dried for later use.

4. The second hydrothermal synthesis solution preparation

Weigh tetrapropyl ammonium hydroxide, tetraethyl silicate, sodium hydroxide and deionized water in a molar ratio of TPAOH:TEOS:NaOH:H ₂ O=0.21:0.75:0.65:100, and mix and stir at room temperature for 6 hours.

5. Second Hydrothermal Synthesis

The pretreated samples were hydrothermally synthesized at 180 °C for 20 h, taken out, washed twice with deionized water, dried, and recorded as TS-4.

Example 4

1. Sample surface cleaning

H13 die steel is sanded and then cleaned with aqueous nitric acid and deionized water.

2. Preparation of Pretreatment Synthesis Solution

Weigh tetrapropylammonium hydroxide, tetraethyl silicate, sodium hydroxide and deionized water in a molar ratio of TPAOH:TEOS:NaOH:H ₂ O=0.15:0.5:0.45:100, and mix and stir at room temperature for 6 hours.

3. The first hydrothermal pre-synthesis

The homogeneously mixed synthesis solution was poured into the reaction kettle containing the samples, and hydrothermally synthesized at 175 °C for 5 h. After taking out, the samples were washed twice with deionized water and dried for later use.

4. Preparation of secondary hydrothermal synthesis solution

Weigh tetrapropyl ammonium hydroxide, tetraethyl silicate, sodium hydroxide and deionized water in a molar ratio of TPAOH:TEOS:NaOH:H ₂ O=0.21:0.75:0.65:100, and mix and stir at room temperature for 6 hours.

5. Second Hydrothermal Synthesis

The pretreated samples were hydrothermally synthesized at 180 °C for 20 h, taken out, washed twice with deionized water, dried, and recorded as TS-5.

Example 5

1. Sample surface cleaning

The 3Cr2W8V die steel is sanded and then cleaned with aqueous nitric acid and deionized water.

2. Preparation of Pretreatment Synthesis Solution

Weigh tetrapropylammonium hydroxide, tetraethyl silicate, sodium hydroxide and deionized water respectively according to the molar ratio TPAOH:TEOS:NaOH:H ₂ O=0.15:0.5:0.45:100, and mix and stir at room temperature for 6h.

3. The first hydrothermal pre-synthesis

The homogeneously mixed synthesis solution was poured into the reaction kettle with the samples, and hydrothermally synthesized at 175 °C for 3 h. After taking out, the samples were washed twice with deionized water and dried for later use.

4. The second hydrothermal synthesis solution preparation

Weigh tetrapropyl ammonium hydroxide, tetraethyl silicate, sodium hydroxide and deionized water in a molar ratio of TPAOH:TEOS:NaOH:H ₂ O=0.21:0.75:0.65:100, and mix and stir at room temperature for 6 hours.

5. Second Hydrothermal Synthesis

The pretreated samples were hydrothermally synthesized at 180 °C for 20 h, taken out, washed twice with deionized water, and dried.

Example 6

1. Sample surface cleaning

The 5CrNiMo die steel was sanded and then cleaned with aqueous nitric acid and deionized water.

2. Preparation of Pretreatment Synthesis Solution

Weigh tetrapropylammonium hydroxide, tetraethyl silicate, sodium hydroxide and deionized water respectively according to the molar ratio TPAOH:TEOS:NaOH:H ₂ O=0.15:0.6:0.4:100, and mix and stir at room temperature for 6h.

3. The first hydrothermal pre-synthesis

The homogeneously mixed synthesis solution was poured into the reaction kettle with the samples, and hydrothermally synthesized at 175 °C for 3 h. After taking out, the samples were washed twice with deionized water and dried for later use.

4. The second hydrothermal synthesis solution preparation

Weigh tetrapropyl ammonium hydroxide, tetraethyl silicate, sodium hydroxide and deionized water in a molar ratio of TPAOH:TEOS:NaOH:H ₂ O=0.25:0.8:0.65:100, and mix and stir at room temperature for 6 hours.

5. Second Hydrothermal Synthesis

The pretreated samples were hydrothermally synthesized at 180 °C for 20 h, taken out, washed twice with deionized water, and dried.

Comparative Example 1

1. Sample surface cleaning

H13 die steel is sanded and then cleaned with aqueous nitric acid and deionized water.

2. Hydrothermal synthesis solution preparation

Weigh tetrapropylammonium hydroxide, tetraethyl silicate, sodium hydroxide and deionized water in a molar ratio of TPAOH:TEOS:NaOH:H ₂ O=0.15:0.5:0.45:100, and mix and stir at room temperature for 6 hours.

3. Direct one-time hydrothermal synthesis

Pour the evenly mixed synthesis solution into the reaction kettle with the samples, and perform hydrothermal synthesis at 175°C for 24 hours. After taking out, the samples are washed twice with deionized water and dried, which is designated as S-24.

Claims (9)

1. a preparation method of steel mold surface heat-resistant, wear-resistant, corrosion-resistant zeolite coating, is characterized in that: firstly adopt first hydrothermal pre-synthesis to deposit silicon gel thin layer and small particle zeolite on steel mold surface, then adopt The second hydrothermal synthesis continued to deposit the silica gel layer, and at the same time promoted the growth of small-particle zeolite, and during the second hydrothermal synthesis, new small-particle zeolite was formed and filled between the grown zeolite particles, growing and stacking alternately. A continuous dense zeolite particle membrane layer is formed by grading zeolite particles of different sizes, and the stacked silica gel layer and the zeolite particle membrane layer form a zeolite coating. 2. The preparation method of a heat-resistant, wear-resistant, and corrosion-resistant zeolite coating on the surface of a steel mold according to claim 1, characterized in that: the steel mold material is die-casting, extrusion, forging, drawing, stamping and Various types of hot work, warm work or cold work die steel for plastic product molding. 3. the preparation method of a kind of steel mold surface heat-resistant, wear-resistant, corrosion-resistant zeolite coating according to claim 1, is characterized in that: described steel mold surface first carries out grinding, acid/lye treatment, deionized water cleaning , to remove surface impurities and oil stains. 4. the preparation method of a kind of heat-resistant, wear-resistant, corrosion-resistant zeolite coating on the surface of a steel mold according to claim 1, is characterized in that: the preparation of the synthetic liquid that the hydrothermal pre-synthesis adopts for the first time is: the tetrapropyl The molar ratio of ammonium hydroxide, tetraethyl silicate, sodium hydroxide and deionized water is TPAOH:TEOS:NaOH:H ₂ O=(0.1～0.2):(0.4～1):(0.3～0.5):100 Mix and stir for 3 to 15 hours. 5. the preparation method of a kind of steel mold surface heat-resistant, wear-resistant and corrosion-resistant zeolite coating according to claim 1, is characterized in that: the temperature of the first hydrothermal pre-synthesis is 150～190 ℃, and the time is 1～190 ℃ 6h. 6. the preparation method of a kind of steel mold surface heat-resistant, wear-resistant and corrosion-resistant zeolite coating according to claim 1, is characterized in that: the preparation of the synthetic liquid that hydrothermal synthesis adopts for the second time is: the tetrapropyl hydrogen The molar ratio of ammonium oxide, tetraethyl silicate, sodium hydroxide and deionized water is TPAOH:TEOS:NaOH:H ₂ O=(0.16~0.35):(0.7~1.5):(0.6~1):100 mixed Stir for 3 to 15 hours. 7. The preparation method of a heat-resistant, wear-resistant, and corrosion-resistant zeolite coating on the surface of a steel mold according to claim 1, wherein the temperature of the second hydrothermal synthesis is 170-220°C, and the time is 8-38h . 8. The heat-resistant, wear-resistant, and corrosion-resistant zeolite coating prepared by the preparation method according to any one of claims 1-7, wherein the zeolite coating comprises a two-layer structure, and the first layer is the surface of the steel mold. The silica gel layer, and the second layer is the zeolite particle membrane layer on the silica gel layer. 9 . The heat-resistant, wear-resistant, and corrosion-resistant zeolite coating according to claim 8 , wherein 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 zeolite particle membrane The thickness of the layer is 1 to 40 μm.

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