Chromium coating modified on basis of v 2o 5 and preparation method therefor

Abstract

The present application discloses a chromium coating modified on the basis of V2O5 and a preparation method therefor. Components of a solid-phase diffusion agent used are: Cr: 30-50%; V2O5: 2-7%; SiC: 30-50%; NH4Cl: 1-5%; La2O3: 0-5%; and Y2O3: 2-5%. The chromium coating prepared in the present application has a uniform structure, a moderate thickness, sufficient diffusion of Cr atoms, and good metallurgical bonding between a diffusion layer and a substrate, is suitable for austenitic steel and high-temperature alloy components which are used in large boilers, oil and gas field transportation pipelines and other workpieces having a large aspect ratio and various complex shapes, and achieves excellent industrial mass production benefits.

Description

A chromium coating based on V2O5 modification and a preparation method thereof

[0001] Cross-reference to Related Applications

[0002] This application claims priority to the Chinese patent application No. 202411286861.0, filed on September 13, 2024, and entitled "A chromium coating based on V2O5 modification and a preparation method thereof", the entire contents of which are incorporated herein by reference. TECHNICAL FIELD

[0003] The present application belongs to the technical field of material surface alloying and coating preparation, and specifically relates to a chromium coating based on V2O5 modification and a preparation method thereof. BACKGROUND

[0004] The high-temperature corrosion existing on the flue gas side of the boiler pipe of a thermal power plant has become a major hidden danger for the safe operation of the power plant, and the corrosion of the metal of the flue gas side heating surface is mainly caused by a series of chemical reactions of the material surface and the surrounding corrosive medium, such as SO2 in the flue gas after coal combustion, boiler makeup water, and furnace water, steam, air, and fly ash / waste residue, etc., leading to metal corrosion damage; at present, the chromium high-temperature coating is mainly deposited on the surface of the austenitic steel pipe to solve the corrosion problem of the flue gas side of the boiler pipe.

[0005] The existing high-temperature coating technology is mainly used for the hot end components of the aero-engine, such as blades, rotors, turbine discs, etc., which have high temperature, short service time, and small size; for the characteristics of the large length-diameter ratio structure, high temperature, long time, and low stress service environment of the energy equipment flow-through components, the existing coating technology is no longer applicable; on the other hand, the stability of Cr2O3 in steam above 600℃ is poor, and the oxidation film loosening problem caused by the volatile product will cause the oxidation film to peel off, and further cause the pipe blockage and pipe explosion accidents; in addition, the Cr content in the alloy matrix is relatively low, and with the increase of the service time, when the Cr content required for the growth of the oxidation film cannot be supplemented, the corrosion resistance of the alloy will also decrease sharply. Therefore, it is of great practical significance to research and develop a high-performance corrosion-resistant coating suitable for the inner and outer walls of the boiler unit pipe and a preparation process thereof. SUMMARY

[0006] This section is intended to summarize some aspects of the embodiments of the present application and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the abstract and title of the specification to avoid obscuring the purpose of this section, the abstract and the title, and such simplifications or omissions cannot be used to limit the scope of the present application.

[0007] In view of the above and / or the problems existing in the prior art, the present application is proposed.

[0008] Therefore, another object of the present application is to overcome the deficiencies in the prior art and provide a preparation method of a chromium coating based on V2O5 modification.

[0009] To solve the above technical problems, the present application provides the following technical solutions:

[0010] The solid phase component is ball milled to obtain a solid phase penetrant powder;

[0011] The workpiece to be penetrated and the solid phase penetrant powder are subjected to vacuum high-temperature heat treatment, and after cooling, the workpiece containing a chromium coating is obtained.

[0012] The solid phase component comprises, in terms of mass percentage, 30-60% Cr powder, 2-7% V2O5, 30-50% SiC, 1-5% NH4Cl, 0-5% La2O3, and 2-5% Y2O3.

[0013] The Cr powder is sieved through a 1000-mesh sieve.

[0014] As an optional solution of the modification method of the workpiece by the solid phase penetrant described in the present application, the mass percentage of the Cr powder is 40-60%.

[0015] As an optional solution of the modification method of the workpiece by the solid phase penetrant described in the present application, the rotation speed of the ball milling is 350-400 rpm.

[0016] As an optional solution of the modification method of the workpiece by the solid phase penetrant described in the present application, the ball milling time is 12-24 h.

[0017] As an optional solution of the modification method of the workpiece by the solid phase penetrant described in the present application, the workpiece to be penetrated is placed in the middle of the solid phase penetrant powder, and the distance between adjacent workpieces to be penetrated is not less than 10 cm.

[0018] As an optional solution of the modification method of the workpiece by the solid phase penetrant described in the present application, the temperature of the vacuum high-temperature heat treatment is 1000-1150°C.

[0019] As an optional solution of the modification method of the workpiece by the solid phase penetrant described in the present application, the holding time of the vacuum high-temperature heat treatment is 1-5 h.

[0020] As an optional solution of the workpiece containing a chromium coating prepared by the modification method described in the present application, the vacuum degree of the vacuum high-temperature heat treatment is 1×10 -3 -9×10 -3 Pa.

[0021] Still another object of the present application is to overcome the deficiencies in the prior art and provide a chromium coating prepared by the preparation method of the chromium coating based on V2O5 modification, wherein the chromium coating has a thickness of 8.6-40.2 μm and a Cr atomic content of 22.2%-35.4%.

[0022] As an alternative of the chromium coating according to the present application, the chromium coating improves the heat corrosion resistance of the workpiece in a flue gas environment, and after 500 h in a flue gas corrosion environment at 650 ℃, the weight loss of the workpiece with the chromium coating is only 2%-4.16% of the weight loss of the workpiece to be infiltrated, and after 500 h in a flue gas corrosion environment at 750 ℃, the weight loss of the workpiece with the chromium coating is only 2.13%-3.81% of the weight loss of the workpiece to be infiltrated.

[0023] The present application has the following advantages:

[0024] (1) The present application adds rare earth oxides in the solid-phase infiltrant components, which has the effect of accelerating infiltration and activation, improves the infiltration speed and coating quality, and in addition, the rare earth oxides can strengthen the substrate structure and enhance the surface hardness on the basis of promoting infiltration.

[0025] (2) The addition of V2O5 in the present application can enhance the corrosion resistance and thermal strength of the base material, the V element can bind free carbon atoms and inhibit the formation of reticular chromium carbide, and enhance the compactness and oxidation resistance of the Cr coating; on the basis of the halide promoting infiltration, the addition of V2O5 can pin the grain boundary in the form of second phase precipitation, strengthen the substrate structure, improve the surface hardness, and improve the bonding strength between the coating and the base material.

[0026] (3) The present application improves the vapor pressure of the halide by carrying out the embedding infiltration in a vacuum environment, and reduces the influence of other residual gases on the infiltration layer.

[0027] (4) The infiltrant components used in the present application do not contain toxic, harmful or polluting components, and the residual infiltrant powder after embedding can be recycled and reused multiple times. BRIEF DESCRIPTION OF DRAWINGS

[0028] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor. Among them:

[0029] Fig. 1 is a cross-sectional morphology diagram of the V2O5 modified chromium coating in Example 1 of the present application.

[0030] Fig. 2 is a cross-sectional morphology diagram of the chromium coating in Example 10 of the present application.

[0031] Figure 3 is a cross-sectional morphology of the chromium coating in the comparative example 1 of the present application.

[0032] Figure 4 is a cross-sectional morphology of the chromium coating in the comparative example 2 of the present application.

[0033] Figure 5 is a cross-sectional morphology of the chromium coating in the comparative example 3 of the present application. DETAILED DESCRIPTION

[0034] In order to make the above objectives, features and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application are described in detail below with reference to the embodiments of the present application.

[0035] In the following description, a large number of specific details are set forth in order to facilitate a thorough understanding of the present application, but the present application can also be implemented in other ways different from those described herein, and those skilled in the art can make similar generalizations without departing from the connotation of the present application, therefore the present application is not limited by the specific embodiments disclosed below.

[0036] Secondly, the "one embodiment" or "embodiment" referred to herein means that the specific features, structures or characteristics can be included in at least one implementation of the present application. "In one embodiment" appearing in different places in the specification does not mean the same embodiment, nor is it an embodiment that is independent of or selected from other embodiments.

[0037] The material to be infiltrated in the present application is generally a steel pipe for the heating surface of a power station boiler, such as Super304H, TP347H, TP347HFG, etc.

[0038] In the present application, the chromium coating thickness determination method is as follows: taking the cross section of the chromium coating sample, under the scanning electron microscope (SEM), the coating thickness is measured according to the appearance morphology of the coating and the corresponding scale.

[0039] In the present application, the chromium coating Cr atomic content determination method is as follows: taking the cross section of the chromium coating sample, under the scanning electron microscope (SEM), the Cr content at the corresponding position of the coating is determined by using energy spectrum analysis (EDS).

[0040] In the present application, the determination method of the corrosion resistance of the material under high temperature conditions is as follows: the material sample is placed in a boiler flue gas simulation environment (the gas contains CO2, SO2, CO, H2O, etc., and the temperature is 650℃) to test the corrosion resistance, and the time is 500h.

[0041] The quantitative index of the corrosion resistance of the material in the present application is the corrosion weight gain per unit area of the sample, and the calculation method is: corrosion weight gain = (sample weight at target corrosion time - original sample weight) / sample surface area.

[0042] Example 1

[0043] The embodiment provides a chromium coating based on V2O5 modification and a preparation method thereof.

[0044] The workpiece to be infiltrated is taken out, high-pressure airflow is used to wash for 15 minutes to remove oil stains, dust and the like on the surface of the workpiece and remove the oxide skin, after cleaning, the surface of the workpiece is polished to a roughness Ra less than 0.8 microns by using a metallographic sandpaper, then the surface of the workpiece is cleaned for 30 seconds by using hydrochloric acid and hydrofluoric acid with a mass concentration of 0.5%, after completion, the workpiece is cleaned by using deionized water and alcohol in sequence and dried;

[0045] Solid phase components are weighed according to mass proportions, including 30% of Cr, 7% of V2O5, 50% of SiC, 5% of NH4Cl, 4% of La2O3 and 4% of Y2O3, wherein the Cr powder is a source of infiltration, the V2O5 is a modifier, the SiC is a filler, the NH4Cl is an activator, and the La2O3 and Y2O3 are infiltration accelerators, and the solid phase infiltration agent is obtained by placing them in a planetary ball mill at 400 rpm for 24 hours;

[0046] The workpiece to be infiltrated and the infiltration agent are placed in the embedding infiltration groove, the workpiece to be infiltrated is placed in the middle of the infiltration agent powder, and the distance between adjacent workpieces is not less than 10 cm; and the workpiece to be infiltrated is infiltrated at 1x10 -3 Pa vacuum degree, heat treatment is performed at a heat treatment temperature of 1000 DEG C and a heat preservation time of 4 hours, and the workpiece is cooled to room temperature after heat preservation is completed, to obtain a workpiece containing a chromium coating.

[0047] Embodiment 2

[0048] The embodiment provides a chromium coating based on V2O5 modification and a preparation method thereof.

[0049] The workpiece to be infiltrated is taken out, high-pressure airflow is used to wash for 15 minutes to remove oil stains, dust and the like on the surface of the workpiece and remove the oxide skin, after cleaning, the surface of the workpiece is polished to a roughness Ra less than 0.8 microns by using a metallographic sandpaper, then the surface of the workpiece is cleaned for 30 seconds by using hydrochloric acid and hydrofluoric acid with a mass concentration of 0.5%, after completion, the workpiece is cleaned by using deionized water and alcohol in sequence and dried;

[0050] Solid phase components are weighed according to mass proportions, including 30% of Cr, 7% of V2O5, 50% of SiC, 5% of NH4Cl, 4% of La2O3 and 4% of Y2O3, wherein the Cr powder is a source of infiltration, the V2O5 is a modifier, the SiC is a filler, the NH4Cl is an activator, and the La2O3 and Y2O3 are infiltration accelerators, and the solid phase infiltration agent is obtained by placing them in a planetary ball mill at 400 rpm for 24 hours;

[0051] The workpiece to be infiltrated and the infiltration agent are placed in the embedding infiltration groove, the workpiece to be infiltrated is placed in the middle of the infiltration agent powder, and the distance between adjacent workpieces is not less than 10 cm; and the workpiece to be infiltrated is infiltrated at 1x10 -3 Pa vacuum degree, heat treatment is performed at a heat treatment temperature of 1000 DEG C and a heat preservation time of 4 hours, and the workpiece is cooled to room temperature after heat preservation is completed, to obtain a workpiece containing a chromium coating.

[0052] Example 3

[0053] The embodiment provides a chromium coating based on V2O5 modification and a preparation method thereof.

[0054] The workpiece to be infiltrated is taken out, high-pressure airflow is used to wash for 15 minutes to remove oil stains, dust and the like on the surface of the workpiece and remove the oxide skin, after cleaning, the surface of the workpiece is polished to a roughness Ra less than 0.8 μm by using metallographic sandpaper, then the surface of the workpiece is cleaned for 30 seconds by using hydrochloric acid and hydrofluoric acid with a mass concentration of 0.5%, after completion, the workpiece is cleaned by using deionized water and alcohol in sequence and dried;

[0055] The solid-phase components are weighed according to the mass proportion, including 40% of Cr, 7% of V2O5, 43% of SiC, 5% of NH4Cl and 5% of La2O3, and the solid-phase infiltrant is obtained by placing the components in a planetary ball mill at 400 rpm for 24 hours;

[0056] The workpiece to be infiltrated and the infiltrant are placed in the embedding infiltration groove, the workpiece to be infiltrated is placed in the middle of the infiltrant powder, and the distance between adjacent workpieces is not less than 10 cm; and the workpiece to be infiltrated is infiltrated at 9x10 -3 Pa vacuum degree, heat treatment is performed at a heat treatment temperature of 1000 DEG C and a heat preservation time of 4 hours, and the workpiece with the chromium coating is obtained after cooling to room temperature.

[0057] Example 4

[0058] The embodiment provides a chromium coating based on V2O5 modification and a preparation method thereof.

[0059] The workpiece to be infiltrated is taken out, high-pressure airflow is used to wash for 15 minutes to remove oil stains, dust and the like on the surface of the workpiece and remove the oxide skin, after cleaning, the surface of the workpiece is polished to a roughness Ra less than 0.8 μm by using metallographic sandpaper, then the surface of the workpiece is cleaned for 30 seconds by using hydrochloric acid and hydrofluoric acid with a mass concentration of 0.5%, after completion, the workpiece is cleaned by using deionized water and alcohol in sequence and dried;

[0060] The solid-phase components are weighed according to the mass proportion, including 40% of Cr, 7% of V2O5, 43% of SiC, 5% of NH4Cl and 5% of Y2O3, and the solid-phase infiltrant is obtained by placing the components in a planetary ball mill at 350 rpm for 20 hours;

[0061] The workpiece to be infiltrated and the infiltrant are placed in the embedding infiltration groove, the workpiece to be infiltrated is placed in the middle of the infiltrant powder, and the distance between adjacent workpieces is not less than 10 cm; and the workpiece to be infiltrated is infiltrated at 9x10 -3 Pa vacuum degree, heat treatment is performed at a heat treatment temperature of 1000 DEG C and a heat preservation time of 4 hours, and the workpiece with the chromium coating is obtained after cooling to room temperature.

[0062] Example 5

[0063] The embodiment provides a chromium coating based on V2O5 modification and a preparation method thereof.

[0064] The workpiece to be infiltrated is taken out, high-pressure airflow is used to wash the workpiece for 15 minutes to remove oil stains, dust and the like on the surface of the workpiece and remove the oxide skin, after cleaning, the surface of the workpiece is polished to a roughness Ra less than 0.8 μm by using metallographic sandpaper, then the surface of the workpiece is cleaned for 30 seconds by using hydrochloric acid and hydrofluoric acid with a mass concentration of 0.5%, after completion, the workpiece is cleaned by using deionized water and alcohol in sequence and dried;

[0065] The solid-phase components are weighed according to the mass proportion, including 40% of Cr, 2% of V2O5, 45% of SiC, 5% of NH4Cl, 4% of La2O3 and 4% of Y2O3, and the solid-phase infiltrant is obtained by placing the components in a planetary ball mill at 400 rpm for 24 hours;

[0066] The workpiece to be infiltrated and the infiltrant are placed in the embedding infiltration groove, the workpiece to be infiltrated is placed in the middle of the infiltrant powder, and the distance between adjacent workpieces is not less than 10 cm; and the workpiece to be infiltrated is infiltrated at 1 x 10 -3 Pa vacuum degree, heat treatment is performed at a heat treatment temperature of 1050 DEG C and a heat preservation time of 4 hours, and the workpiece with the chromium coating is obtained after cooling to room temperature.

[0067] Embodiment 6

[0068] The embodiment provides a chromium coating based on V2O5 modification and a preparation method thereof.

[0069] The workpiece to be infiltrated is taken out, high-pressure airflow is used to wash the workpiece for 5 minutes to remove oil stains, dust and the like on the surface of the workpiece and remove the oxide skin, after cleaning, the surface of the workpiece is polished to a roughness Ra less than 0.8 μm by using metallographic sandpaper, then the surface of the workpiece is cleaned for 30 seconds by using hydrochloric acid and hydrofluoric acid with a mass concentration of 0.5%, after completion, the workpiece is cleaned by using deionized water and alcohol in sequence and dried;

[0070] The solid-phase components are weighed according to the mass proportion, including 40% of Cr, 2% of V2O5, 45% of SiC, 5% of NH4Cl, 4% of La2O3 and 4% of Y2O3, and the solid-phase infiltrant is obtained by placing the components in a planetary ball mill at 400 rpm for 24 hours;

[0071] The workpiece to be infiltrated and the infiltrant are placed in the embedding infiltration groove, the workpiece to be infiltrated is placed in the middle of the infiltrant powder, and the distance between adjacent workpieces is not less than 10 cm; and the workpiece to be infiltrated is infiltrated at 1 x 10 -3 Pa vacuum degree, heat treatment is performed at a heat treatment temperature of 1050 DEG C and a heat preservation time of 4 hours, and the workpiece with the chromium coating is obtained after cooling to room temperature.

[0072] Embodiment 7

[0073] The embodiment provides a chromium coating based on V2O5 modification and a preparation method thereof.

[0074] The workpiece to be infiltrated is taken out, high-pressure water is used to wash for 10 minutes to remove oil stains, dust and the like on the surface of the workpiece and remove the oxide skin, after cleaning, the surface of the workpiece is polished to a roughness Ra less than 0.8 μm by using metallographic sandpaper, then the surface of the workpiece is cleaned for 20 seconds by using hydrochloric acid and hydrofluoric acid with a mass concentration of 0.5%, after completion, the workpiece is cleaned by using deionized water and alcohol in sequence and dried;

[0075] Solid phase components are weighed according to mass proportions, including 40% of Cr, 7% of V2O5, 42% of SiC, 5% of NH4Cl, 2% of La2O3 and 4% of Y2O3, the solid phase infiltrant is obtained by placing the components in a planetary ball mill and ball milling at 400 rpm for 18 hours;

[0076] The workpiece to be infiltrated and the infiltrant are placed in the embedding infiltration groove, the workpiece to be infiltrated is placed in the middle of the infiltrant powder, and the distance between adjacent workpieces is not less than 10 cm; and the workpiece to be infiltrated is infiltrated at 1 x 10 -3 Pa vacuum degree, heat treatment is performed at a heat treatment temperature of 1150 DEG C and a heat preservation time of 2 hours, and the workpiece with the chromium coating is obtained after cooling to room temperature.

[0077] Embodiment 8

[0078] The embodiment provides a chromium coating based on V2O5 modification and a preparation method thereof.

[0079] The workpiece to be infiltrated is taken out, high-pressure water is used to wash for 10 minutes to remove oil stains, dust and the like on the surface of the workpiece and remove the oxide skin, after cleaning, the surface of the workpiece is polished to a roughness Ra less than 0.8 μm by using metallographic sandpaper, then the surface of the workpiece is cleaned for 20 seconds by using hydrochloric acid and hydrofluoric acid with a mass concentration of 0.5%, after completion, the workpiece is cleaned by using deionized water and alcohol in sequence and dried;

[0080] Solid phase components are weighed according to mass proportions, including 40% of Cr, 7% of V2O5, 42% of SiC, 5% of NH4Cl, 2% of La2O3 and 4% of Y2O3, the solid phase infiltrant is obtained by placing the components in a planetary ball mill and ball milling at 400 rpm for 18 hours;

[0081] The workpiece to be infiltrated and the infiltrant are placed in the embedding infiltration groove, the workpiece to be infiltrated is placed in the middle of the infiltrant powder, and the distance between adjacent workpieces is not less than 10 cm; and the workpiece to be infiltrated is infiltrated at 1 x 10 -3 Pa vacuum degree, heat treatment is performed at a heat treatment temperature of 1150 DEG C and a heat preservation time of 2 hours, and the workpiece with the chromium coating is obtained after cooling to room temperature.

[0082] Embodiment 9

[0083] The embodiment provides a chromium coating based on V2O5 modification and a preparation method thereof.

[0084] The workpiece to be infiltrated is taken out, high-pressure airflow is used for washing for 15 minutes to remove oil stains, dust and the like on the surface of the workpiece and remove the oxide skin, after cleaning, the surface of the workpiece is polished to a roughness Ra less than 0.8 μm by using metallographic sandpaper, then the surface of the workpiece is cleaned for 30 seconds by using hydrochloric acid and hydrofluoric acid with a mass concentration of 0.5%, after completion, the workpiece is cleaned by using deionized water and alcohol in sequence and dried;

[0085] Solid phase components are weighed according to mass proportions, including 35% of Cr, 5% of V2O5, 50% of SiC, 5% of NH4Cl, 2% of La2O3 and 3% of Y2O3, and the solid phase infiltrant is obtained by placing the components in a planetary ball mill and ball milling at 350 rpm for 24 hours;

[0086] The workpiece to be infiltrated and the infiltrant are placed in the embedding infiltration groove, the workpiece to be infiltrated is placed in the middle of the infiltrant powder, and the distance between adjacent workpieces is not less than 10 cm; and the workpiece to be infiltrated is infiltrated at 1x10 -3 Pa vacuum degree, heat treatment is performed at a heat treatment temperature of 1050 DEG C and a heat preservation time of 5 hours, and the workpiece with the chromium coating is obtained after cooling to room temperature.

[0087] Embodiment 10

[0088] The embodiment provides a chromium coating based on V2O5 modification and a preparation method thereof.

[0089] The workpiece to be infiltrated is taken out, high-pressure airflow is used for washing for 15 minutes to remove oil stains, dust and the like on the surface of the workpiece and remove the oxide skin, after cleaning, the surface of the workpiece is polished to a roughness Ra less than 0.8 μm by using metallographic sandpaper, then the surface of the workpiece is cleaned for 30 seconds by using hydrochloric acid and hydrofluoric acid with a mass concentration of 0.5%, after completion, the workpiece is cleaned by using deionized water and alcohol in sequence and dried;

[0090] Solid phase components are weighed according to mass proportions, including 35% of Cr, 5% of V2O5, 50% of SiC, 5% of NH4Cl, 2% of La2O3 and 3% of Y2O3, and the solid phase infiltrant is obtained by placing the components in a planetary ball mill and ball milling at 350 rpm for 24 hours;

[0091] The workpiece to be infiltrated and the infiltrant are placed in the embedding infiltration groove, the workpiece to be infiltrated is placed in the middle of the infiltrant powder, and the distance between adjacent workpieces is not less than 10 cm; and the workpiece to be infiltrated is infiltrated at 1x10 -3 Pa vacuum degree, heat treatment is performed at a heat treatment temperature of 1150 DEG C and a heat preservation time of 4 hours, and the workpiece with the chromium coating is obtained after cooling to room temperature. The chromium coating is shown in Fig. 3.

[0092] Embodiment 11

[0093] The embodiment provides a chromium coating based on V2O5 modification and a preparation method thereof.

[0094] The workpiece to be infiltrated is taken out, high-pressure airflow is used to wash the workpiece for 15 minutes to remove oil stains, dust and the like on the surface of the workpiece and remove the oxide skin, after the cleaning, the surface of the workpiece is polished to a roughness Ra less than 0.8 μm by using a metallographic sandpaper, then the surface of the workpiece is cleaned by using 0.5% hydrochloric acid and hydrofluoric acid for 30 seconds, after the cleaning, the workpiece is cleaned by using deionized water and alcohol in sequence and is dried;

[0095] Solid-phase components are weighed according to mass proportions, including 60% of Cr, 7% of V2O5, 50% of SiC, 5% of NH4Cl, 4% of La2O3 and 4% of Y2O3, the solid-phase components are placed in a planetary ball mill to be ball milled at 400 rpm for 24 hours, and a solid-phase infiltrant is obtained;

[0096] The workpiece to be infiltrated and the infiltrant are placed in an embedding infiltration groove, the workpiece to be infiltrated is placed in the middle of the infiltrant powder, and the distance between adjacent workpieces is not less than 10 cm; the workpiece to be infiltrated is infiltrated at 1 x 10 -3 Pa vacuum degree, heat treatment is performed at a heat treatment temperature of 1000 ℃ and a heat preservation time of 4 hours, and the workpiece with the chromium coating is obtained after cooling to room temperature.

[0097] The thickness, Cr atomic content and corrosion resistance of the chromium coating prepared in Comparative Examples 1-11 are compared, as shown in Table 1.

[0098] Table 1: Comparison of thickness, Cr atomic content and corrosion resistance of the chromium coating in Examples 1-11

[0099] The corrosion resistance of the base material (workpiece to be infiltrated) in a 650 ℃ flue gas corrosion environment is 500 h with a weight loss of 15 mg / cm 2 , the corrosion resistance in a 750 ℃ flue gas corrosion environment is 500 h with a weight loss of 18 mg / cm 2 .

[0100] The thicker the chromium coating is, the higher the chromium content is, and the better the dense chromium oxide formed on the surface is, so that the corrosion resistance is improved by a higher multiple. The chromium coating in the workpiece with the chromium coating has a thickness of 8.6-40.2 μm, a Cr atomic content of 22.2%-35.4%, and is well combined with the base material; after 500 h in a 650 ℃ flue gas corrosion environment, the weight loss is only 2%-4.16% of the base material, and after 500 h in a 750 ℃ flue gas corrosion environment, the weight loss is only 2.13%-3.81% of the base material.

[0101] Comparative Example 1

[0102] The difference between the present comparative example and Example 10 is that the solid phase penetrant component does not contain La2O3 and Y2O3, and other steps are the same as those of Example 10, thereby preparing a chromium coating.

[0103] The cross-section microstructure is shown in Fig. 3, the chromium coating is not uniform and discontinuous, and the quality of the chromium coating is quite different from that in Example 10, which indicates that La2O3 and Y2O3 play a key role in promoting the formation of the chromium coating on the surface of the workpiece to be penetrated.

[0104] Comparative Example 2

[0105] The difference between the present comparative example and Example 1 is that the solid phase penetrant does not contain V2O5, and other operations are the same as those of Example 1, thereby preparing a workpiece containing a chromium coating.

[0106] The present comparative example does not contain V2O5, and the cross-section microstructure is shown in Fig. 4, the chromium coating is not uniform and discontinuous, and the quality of the chromium coating is quite different from that in Example 1, which indicates that V2O5 plays a key role in promoting the formation of the chromium coating on the surface of the workpiece to be penetrated.

[0107] Comparative Example 3

[0108] The difference between the present comparative example and Example 1 is that the solid phase penetrant component contains only Cr powder, and other operations are the same as those of Example 1, thereby preparing a workpiece containing a chromium coating.

[0109] The solid phase penetrant component of the present comparative example contains only Cr powder, and the cross-section microstructure is shown in Fig. 5, Cr does not penetrate into the matrix material, but only partially melts and adheres to the surface of the matrix, and an effective penetration layer is not prepared, which indicates that other solid phase penetrants play a key role in the formation of the penetration layer.

[0110] Comparative Example 4

[0111] The difference between the present comparative example and Example 1 is that the solid phase penetrant component does not contain the filler SiC, and other operations are the same as those of Example 1.

[0112] The penetration layer prepared in the present comparative example is discontinuous and non-uniform, and the morphology is similar to that shown in Fig. 3, which shows that the mixing of the filler SiC with Cr can make Cr uniformly dispersed, and when the mixed solid phase adheres to the surface of the matrix, Cr maintains a suitable concentration, which indicates that the SiC filler plays a key role in the formation of the chromium coating.

[0113] Comparative Example 5

[0114] The difference between the present comparative example and Example 1 is that the solid phase penetrant component does not contain NH4Cl, and other operations are the same as those of Example 1, thereby preparing a workpiece containing a chromium coating.

[0115] The coating prepared in the present comparative example is thinner by about 10% of the coating prepared in Example 1, and thus it can be seen that the NH4Cl has a significant effect on the formation of the chromium coating on the surface of the workpiece to be infiltrated during the sintering process.

[0116] In summary, the chromium coating with a thickness of 8.6-40.2 μm and a Cr atomic content of 22.2%-35.4% in good metallurgical combination is prepared by adjusting the content of the infiltrant, the content of the rare earth oxide and the heat treatment parameters, etc. The chromium coating effectively improves the heat corrosion resistance of the alloy base material in the flue gas environment.

[0117] It should be noted that the above examples are only used to illustrate the technical solutions of the present application and are not limiting. Although the present application has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solutions of the present application can be modified or replaced equivalently without departing from the spirit and scope of the technical solutions of the present application, and they should be covered in the scope of the claims of the present application.

Claims

A method for the production of a chromium coating based on V2O5 modification, characterized in that The method comprises the following steps: The solid phase component is ball milled to obtain a solid phase infiltrant powder; The workpiece to be infiltrated and the solid phase infiltrant powder are subjected to vacuum high-temperature heat treatment, and the workpiece to be infiltrated is taken out after cooling to obtain a workpiece with a chromium coating; The solid phase component comprises, in percentage by mass, 30-60% of Cr powder, 2-7% of V2O5, 30-50% of SiC, 1-5% of NH4Cl, 0-5% of La2O3, and 2-5% of Y2O3. Process for the preparation of a V2O5-modified chromium coating according to claim 1, characterized in that The percentage by mass of the Cr powder is 40-60%. Process for the preparation of a V2O5-modified chromium coating according to claim 1, characterized in that The rotation speed of the ball milling is 350-400 rpm. Process for the preparation of a V2O5-modified chromium coating according to claim 3, characterized in that The ball milling time is 12-24 h. Process for the preparation of a V2O5-modified chromium coating according to claim 1, characterized in that The workpiece to be infiltrated is placed in the middle of the solid phase infiltrant powder, and the distance between adjacent workpieces to be infiltrated is not less than 10 cm. Process for the preparation of a V2O5-modified chromium coating according to claim 1, characterized in that The temperature of the vacuum high-temperature heat treatment is 1000-1150 ℃. Process for the preparation of a V2O5-modified chromium coating according to claim 6, characterized in that The holding time of the vacuum high-temperature heat treatment is 1-5 h. Process for the preparation of a V2O5-modified chromium coating according to claim 7, characterized in that The vacuum degree of the vacuum high-temperature heat treatment is 1x10 -3 ~ 9x10 -3 Pa. The chromium coating produced according to the method for producing a V2O5-modified chromium coating according to any of claims 1 to 8, characterized by: The thickness of the chromium coating is 8.6-40.2 μm, and the Cr atomic content is 22.2%-35.4%. A chromium coating as claimed in claim 9, characterized in that: The chromium coating improves the heat corrosion resistance of the workpiece in a flue gas environment, and after 500 h in a 650 ℃ flue gas corrosion environment, the weight loss of the workpiece with the chromium coating is only 2%-4.16% of the weight loss of the workpiece to be infiltrated, and after 500 h in a 750 ℃ flue gas corrosion environment, the weight loss of the workpiece with the chromium coating is only 2.13%-3.81% of the weight loss of the workpiece to be infiltrated.

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