CN113860916B - Corrosion-resistant niobium titanium carbide coating, corrosion-resistant silicon carbide container and preparation method and application thereof - Google Patents

Abstract

The invention provides a niobium-titanium carbide corrosion-resistant coating, the chemical composition includes niobium carbide and titanium carbide. The niobium-titanium carbide corrosion-resistant coating of the chemical composition can effectively prevent the erosion caused by the molten fluoride-oxide. Compared with the material without the corrosion-resistant protective layer, the niobium carbide-titanium carbide is solid in the range of 1400-1800 °C, When used on the surface of a silicon carbide electrolytic cell, it can effectively prevent the electrolyte from contacting the silicon carbide electrolytic cell and cause erosion, thereby affecting the process of electrolytic extraction of metals. When the niobium-titanium carbide corrosion-resistant coating is used in an electrolytic cell, it can reduce the chemical corrosion caused by the reaction between Fe ₂ O ₃ , Nb ₂ O ₅ , TiO ₂ in the electrolyte and the base material of the electrolytic cell, and can also prevent O ² in the electrolyte. ^‑ , F ^‑ The thermal erosion of the base material of the electrolytic cell can effectively ensure the smooth progress of electrolytic extraction of metals.

Description

Erosion-resistant niobium-titanium carbide coating, erosion-resistant silicon carbide container and preparation method thereof application

technical field

The invention relates to the technical field of erosion-resistant materials, in particular to an erosion-resistant niobium-titanium carbide coating, an erosion-resistant silicon carbide container, and a preparation method and application thereof.

Background technique

Bayan Obo Mine is a world-famous co-associated deposit of iron, niobium and rare earth. Compared with other minerals, Bayan Obo Mine contains about 20% fluorite. The existence of these fluorides puts forward higher corrosion resistance materials in high temperature experiments. Require. Due to the existence of fluoride, the existing high-temperature ceramic materials are difficult to meet the requirements of long-term work. With the requirement of carbon neutralization in recent years, electrochemical clean metallurgy has been applied in the direct extraction of metals from Bayan Obo minerals. When electrochemically extracting metals from Bayan Obo minerals, due to the existence of a high-temperature oxide-fluoride system, the crucible material needs to meet the requirements of high temperature resistance, electrochemical corrosion resistance, fluoride corrosion resistance, oxide corrosion resistance, electrical inertness, and machinability. However, the corrosion-resistant crucible materials that can be used for a long time in the electrochemical metallurgy of the high-temperature oxide-fluoride system are very limited.

At present, high-temperature ceramic materials with excellent properties, such as zirconia, silicon nitride, boron nitride, silicon carbide and other materials are often used as crucible materials for high-temperature melt experiments, but when the high-temperature melt contains halides, especially those containing In the presence of fluorides, it is difficult for these high temperature ceramic materials to remain chemically inert at high temperatures for extended periods of time. At the same time, there are minerals containing iron, niobium, titanium, etc. in the Bayan Obo mine. These minerals are easy to react with these high-temperature ceramic materials at high temperature. At present, the commonly used high-temperature ceramic materials will react with the melt, resulting in chemical erosion or thermal erosion. There is no report of suitable electrolytic cell materials when dolomite is used as the electrolyte for the extraction of metallic iron, niobium, and titanium.

SUMMARY OF THE INVENTION

In view of this, the present invention provides an erosion-resistant niobium-titanium carbide coating, an erosion-resistant silicon carbide container, and a preparation method and application thereof. Long-term high-temperature erosion, specifically, it can resist long-term high-temperature erosion and chemical erosion of oxide-fluoride systems under high temperature conditions below 1800 °C.

The invention provides a niobium-titanium carbide corrosion-resistant coating, the chemical composition includes niobium carbide and titanium carbide.

Preferably, the thickness of the niobium-titanium carbide corrosion-resistant coating is 40-150 μm.

The present invention provides an erosion-resistant silicon carbide container, comprising a silicon carbide container base and a niobium-titanium carbide erosion-resistant coating adsorbed on the inner surface of the silicon carbide container base. Niobium-titanium carbide corrosion-resistant coating described above.

Preferably, the silicon carbide container base is a silicon carbide electrolytic cell.

The present invention provides raw materials for preparing the niobium-titanium carbide erosion-resistant coating described in the above technical solution, including the following components by mass percentage:

5-30% CaO, 10-50% SiO ₂ , 5-40% CaF ₂ , 0-20% CeO ₂ , 2.5-25% TiO ₂ , 2.5-25% Nb ₂ O ₅ and 2.5 ~ ₂₅ % _Fe2O3 .

The present invention provides the preparation method of the corrosion-resistant niobium-titanium carbide coating described in the above technical solution or the corrosion-resistant silicon carbide container described in the above technical solution, comprising the following steps:

The raw material described in the above technical solution is placed in the silicon carbide container base;

In a protective atmosphere, the silicon carbide container in which the raw material is placed is heated and then kept warm. During the process of heating and holding, the raw material changes into a liquid phase and reacts with the inner surface of the silicon carbide crucible. The in-situ high-temperature reaction in the silicon carbide container substrate forms a niobium-titanium carbide corrosion-resistant coating, and the temperature of the heat preservation is 1300-1800°C.

Preferably, the heating and heating includes continuous heating or segmented heating, and the heating rate of the continuous heating is 1 to 50°C/min;

The step-by-step heating includes the following steps:

heating up to an intermediate temperature at a first heating rate, the first heating rate is 1-50°C/min, and the intermediate temperature is 500-1300°C;

The temperature is raised from the intermediate temperature to the holding temperature at a second heating rate, the second heating rate is 1-50°C/min, and the holding temperature is 1300-1800°C.

Preferably, the incubation time is 12-48h.

Preferably, after the heat preservation, the method further comprises: inverting the silicon carbide container obtained by the heat preservation after cooling, and repeating the heating, temperature increase and heat preservation.

The present invention provides the application of the corrosion-resistant silicon carbide container described in the above technical solution in corrosion-resistant molten fluoride-oxide.

The invention provides a niobium-titanium carbide corrosion-resistant coating, the chemical composition includes niobium carbide and titanium carbide. The chemical composition of the niobium-titanium carbide corrosion-resistant coating can effectively prevent the erosion caused by the molten fluoride-oxide. Compared with the material without the corrosion-resistant protective layer, the niobium carbide-titanium carbide is solid in the range of 1400-1800 °C, When used on the surface of a silicon carbide electrolytic cell, it can effectively prevent the electrolyte from contacting the silicon carbide electrolytic cell and cause erosion, thereby affecting the process of electrolytic extraction of metals. When the niobium-titanium carbide corrosion-resistant coating is used in an electrolytic cell, it can reduce the chemical corrosion caused by the reaction between Fe ₂ O ₃ , Nb ₂ O ₅ , TiO ₂ in the electrolyte and the base material of the electrolytic cell, and can also prevent O ² in the electrolyte. ^- , F ^- The thermal erosion of the base material of the electrolytic cell can effectively ensure the smooth progress of the electrolytic extraction of metals.

The present invention also provides raw materials and a preparation method for preparing the niobium-titanium carbide corrosion-resistant layer, the raw materials include CaO, SiO ₂ , CaF ₂ , CeO ₂ , TiO ₂ , Nb ₂ O ₅ and Fe ₂ O ₃ , so that the When preparing the corrosion-resistant layer from the above-mentioned raw materials, the silicon carbide container is used as the matrix, the raw material is added into the silicon carbide container, and the raw material is changed into a liquid phase by increasing the temperature to contact and react with the silicon carbide container. Silicon has strong solubility, and the niobium carbide-titanium carbide formed after the liquid-phase raw material is contacted with the silicon carbide container is adsorbed on the inner surface of the silicon carbide container, thereby forming an erosion-resistant layer including niobium carbide and titanium carbide.

The preparation method provided by the invention uses a container made of silicon carbide as a substrate, and has good processability. The niobium-titanium carbide corrosion-resistant layer prepared in-situ on the inner surface of the container is not affected by the shape of the container, and the process for preparing the corrosion-resistant layer is simple, The operation is simple and the morphology of the corrosion-resistant layer is easy to control.

Further, increasing the reaction time in the method provided by the present invention can increase the thickness of the erosion layer; increasing the content of TiO ₂ , Nb ₂ O ₅ , Fe ₂ O ₃ (<17.5wt%) in the raw material can improve the compactness of the erosion layer, The erosion resistance effect is further improved.

Description of drawings

In order to illustrate the technical solutions of the embodiments of the present invention more clearly, the following briefly introduces the accompanying drawings used in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained from these drawings without any creative effort.

1 is an application schematic diagram of an erosion-resistant silicon carbide electrolytic cell provided by an embodiment of the present invention;

Fig. 2 is the heating schematic diagram of preparing the corrosion-resistant layer by in-situ high temperature reaction according to the embodiment of the present invention;

3 is a schematic diagram of salt removal of an erosion-resistant layer prepared by an in-situ high-temperature reaction according to an embodiment of the present invention;

Fig. 4 is the scanning electron microscope picture of the corrosion-resistant silicon carbide electrolytic cell section prepared by the embodiment of the present invention;

5 is a composition diagram of a niobium-titanium carbide corrosion-resistant layer prepared in an embodiment of the present invention;

6 is a scanning electron microscope image of the titanium carbide erosion protective layer prepared in Comparative Example 1 of the present invention;

7 is a composition diagram of the titanium carbide erosion protection layer prepared in Comparative Example 1 of the present invention;

Fig. 8 is the scanning electron microscope image of the niobium carbide erosion protective layer prepared by comparative example 2 of the present invention;

9 is a composition diagram of the niobium carbide corrosion protection layer prepared in Comparative Example 2 of the present invention;

10 is a scanning electron microscope image of the titanium carbide-niobium carbide and the etched layer doped with partial salt prepared in Comparative Example 3 of the present invention;

11 is a scanning electron microscope image of the corrosion-resistant layer prepared in Example 4 of the present invention;

Fig. 12 is an inspection diagram of the crucible obtained by the present invention without an erosion protective layer after an experiment.

Detailed ways

The invention provides a niobium-titanium carbide corrosion-resistant layer, the chemical composition includes niobium carbide and titanium carbide.

The atomic ratio of niobium element and titanium element in the niobium-titanium carbide corrosion-resistant layer provided by the present invention is preferably 1:1 to 1:3.5; the niobium-titanium carbide corrosion-resistant layer preferably includes the following elements in atomic percentage: 54.2% of C, 34.7% Ti and 9.8% Nb. In the present invention, the thickness of the niobium-titanium carbide corrosion-resistant layer is preferably 40-150 μm, more preferably 50-150 μm; in the embodiment of the present invention, the thickness of the niobium-titanium carbide corrosion-resistant layer may be specifically 50 μm , 80μm, 100μm or 150μm.

In the present invention, the niobium-titanium carbide erosion-resistant layer is used on the surface of the silicon carbide container, thereby providing an erosion-resistant silicon carbide container. In the present invention, the erosion-resistant silicon carbide container includes a silicon carbide container base and a niobium carbide erosion-resistant coating adsorbed on the inner surface of the silicon carbide container base, and the niobium-titanium carbide erosion-resistant coating is described in the above technical solution Niobium carbide titanium corrosion resistant layer.

The present invention has no special limitation on the type of the silicon carbide container, which can be any container made of silicon carbide, such as a silicon carbide electrolytic cell and a silicon carbide crucible.

In order to prepare the above-mentioned niobium-titanium carbide corrosion-resistant layer, the present invention also provides preparation raw materials, including the following components by mass percentage:

5-30% CaO, 10-50% SiO ₂ , 5-40% CaF ₂ , 0-20% CeO ₂ , 2.5-25% TiO ₂ , 2.5-25% Nb ₂ O ₅ and 2.5 ~ ₂₅ % _Fe2O3 .

In the present invention, the preparation raw materials preferably include CaO with a mass percentage content of 10-25%, more preferably 15-20%;

The preparation raw materials preferably include SiO ₂ with a mass percentage content of 15-45%, more preferably 30-42%;

The preparation raw material preferably comprises 10-30% by mass of CaF ₂ , more preferably 15-25%, most preferably 15-20%;

The preparation raw material preferably includes CeO ₂ with a mass percentage content of 2-15%, more preferably 5-10%;

The preparation raw material preferably comprises TiO ₂ with a mass percentage content of 5-20%, more preferably 7.5-15%;

The preparation raw materials preferably include Nb ₂ O ₅ with a mass percentage content of 4-20%, more preferably 5-15%;

The preparation raw material preferably includes Fe ₂ O ₃ with a mass percentage content of 4-20%, more preferably 5-17.5%.

In the embodiment of the present invention, the preparation raw materials preferably include: 15.5% CaO, 42% SiO ₂ , 20% CaF ₂ , 5% CeO ₂ , 7.5% TiO ₂ , 5% Nb ₂ O ₅ and 5% Fe ₂ O ₃ .

In the present invention, each component in the preparation raw material is preferably in powder form, and the particle size of the powder is preferably greater than or equal to 200 mesh. In the present invention, the purity of each component in the preparation raw material is preferably >98%.

The present invention also provides a preparation method for preparing a niobium-titanium carbide erosion-resistant layer or an erosion-resistant silicon carbide container by using the raw materials described in the above technical solution, comprising the following steps:

The raw material described in the above technical solution is placed in the silicon carbide container base;

In a protective atmosphere, the silicon carbide container in which the raw material is placed is heated and then kept warm. During the process of heating and holding, the raw material changes into a liquid phase and reacts with the inner surface of the silicon carbide crucible. The in-situ high-temperature reaction in the silicon carbide container substrate forms a niobium-titanium carbide corrosion-resistant coating, and the temperature of the heat preservation is 1300-1800°C.

In the present invention, the raw materials described in the above technical solutions are placed in the base of the silicon carbide container. Preferably, after the raw materials are prepared and shaped, the obtained shaped body is placed in the base of the silicon carbide container. In the present invention, the molding method is preferably tableting; the tableting pressure is preferably 3-10 Mpa, and the pressure-holding time of the tableting is preferably 2-15 min. In the present invention, the molded body is preferably a wafer, and the diameter of the wafer is preferably 10 to 30 mm. The present invention has no particular limitation on the tableting equipment, and a powder tableting machine well known to those skilled in the art can be used.

In the present invention, the ratio of the mass of the raw material to the volume of the silicon carbide container substrate is preferably 1:1 to 1:3

After the raw material is placed in the base of the silicon carbide container, the present invention heats the silicon carbide container with the raw material in a protective atmosphere and then heats it up. The inner surface of the silicon carbide crucible is contacted and reacted, and the niobium-titanium carbide corrosion-resistant coating is formed by an in-situ high-temperature reaction in the silicon carbide container base, and the temperature of the heat preservation is 1300-1800°C.

The present invention has no special restrictions on the equipment for heating, heating and heat preservation, and a heating furnace well-known to those skilled in the art can be used. Specifically, the silicon carbide container with the raw materials is placed in the heating furnace, as shown in FIG. The top of the furnace is provided with a protective gas outlet, and the bottom of the heating furnace is provided with a protective gas inlet. The present invention has no special limitation on the protective atmosphere, and a protective gas well known to those skilled in the art can be used. In the embodiment of the present invention, the protective gas is preferably argon.

In the present invention, the heating and heating is preferably continuous heating or staged heating, and the heating rate of the continuous heating in the present invention is preferably 1-50°C/min, more preferably 5-40°C/min, and most preferably It is 10～20 ℃/min.

In the present invention, the stepwise heating preferably comprises the following steps:

heating up to an intermediate temperature at a first heating rate, the first heating rate is 1-50°C/min, and the intermediate temperature is 500-1300°C;

The temperature is raised from the intermediate temperature to the holding temperature at a second heating rate, the second heating rate is 1-50°C/min, and the holding temperature is 1300-1800°C.

The present invention conducts heat preservation after the temperature rises to the heat preservation temperature, and the time of the heat preservation is preferably 12-48h. In the embodiment of the present invention, the heat preservation may be specifically 12h, 15h, 20h, 24h, 30h, 35h, 40h , 45h or 48h.

In the present invention, the first heating rate is preferably 5-40°C/min, more preferably 10-20°C/min; the intermediate temperature is preferably 700-1200°C, more preferably 1000°C. In the present invention, the second heating rate is preferably 5-40°C/min, more preferably 10-20°C/min; the intermediate temperature is preferably 1400-1600°C, more preferably 1500°C. During the process of temperature increase and heat preservation, the raw material is melted into a liquid phase, and the raw material in the liquid phase contacts and reacts with the inner surface of the silicon carbide to generate niobium carbide and titanium carbide in-situ in the silicon carbide container. The specific reaction process is as follows:

SiC+Fe ₂ O ₃ →Fe/FeSi/Fe ₃ C+SiO ₂ +CO/CO ₂ ;

SiC+Nb ₂ O ₅ →NbC+SiO ₂ ;

SiC+TiO ₂ →TiC+SiO ₂ ;

Fe ₃ C+Nb ₂ O ₅ →Fe+TiC+CO;

Fe ₃ C+TiO ₂ →Fe+TiC+CO.

After the heat preservation, in the present invention, preferably, the silicon carbide container obtained by heat preservation is cooled and then inverted, and the heating, temperature increase and heat preservation are repeated. The present invention has no particular limitation on the cooling method, and a cooling technical solution well-known to those skilled in the art can be adopted, such as cooling with the furnace.

After the cooling, in the present invention, the cooled silicon carbide container is preferably turned upside down, and the heating and temperature-preserving are repeated. As shown in FIG. 3 , in the embodiment of the present invention, the cooled silicon carbide container is hanged upside down in the heating furnace using molybdenum wire, and a larger size silicon carbide container is placed on the periphery of the silicon carbide container for protection. In the present invention, the repeated heating and temperature-raising and heat-retaining are consistent with the solutions of the above-mentioned technical solutions, which are not repeated here. In the embodiment of the present invention, the holding time in the repeated heating and holding is preferably 6h.

In the present invention, through inversion, repeated heating, heating and heat preservation, the raw material is fully left out of the silicon carbide container, and a niobium-titanium carbide corrosion-resistant layer is formed on the inner surface of the silicon carbide container in situ.

The method provided by the invention forms an erosion-resistant layer of niobium-titanium carbide on the inner surface of the silicon carbide container in situ, so that when it is used in a molten fluoride-oxide system, it has the effect of resisting high-temperature erosion and chemical erosion for a longer time.

The embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict; and, based on the embodiments in the present disclosure, those of ordinary skill in the art can obtain the results obtained without creative work. All other embodiments fall within the protection scope of the present disclosure.

It is noted that various aspects of embodiments within the scope of the appended claims are described below. It should be apparent that the aspects described herein may be embodied in a wide variety of forms and that any specific structure and/or function described herein is illustrative only. Based on this disclosure, those skilled in the art should appreciate that an aspect described herein may be implemented independently of any other aspects and that two or more of these aspects may be combined in various ways. For example, an apparatus may be implemented and/or a method may be practiced using any number of the aspects set forth herein. Additionally, such an apparatus may be implemented and/or such a method may be practiced using other structure and/or functionality in addition to one or more of the aspects set forth herein.

Example 1

The raw materials CaO-SiO ₂ -CaF ₂ -CeO ₂ -TiO ₂ -Nb ₂ O ₅ -Fe ₂ O ₃ used in the examples are shown in Table 1

Table 1 CaO-SiO ₂ -CaF ₂ -CeO ₂ -TiO ₂ -Nb ₂ O ₅ -Fe ₂ O ₃ raw material components used in Example 1

Element CaO SiO₂ CaF₂ CeO₂ TiO₂ Nb₂O₅ Fe₂O₃ Content (wt%) 15.5 42 20 5 7.5 5 5

A total of 3.21g of powder raw materials were weighed according to the proportion of each oxide, and the powder raw materials were compressed into a disc with a diameter of 13mm using a powder tablet machine, the pressure was set to 5Mpa, and the pressure holding time was 5min;

The obtained wafer is placed in the silicon carbide electrolytic cell, and the silicon carbide electrolytic cell with the wafer is placed in a heating furnace for heating (the heating schematic diagram is shown in Figure 2). The heating rate of min is raised from room temperature to 1000 °C, and then the temperature is increased from 1000 °C to 1500 °C at a heating rate of 5 °C/min, and the temperature is kept at 1500 °C for 24 hours. After cooling in the furnace, the electrolytic cell is taken out;

Use molybdenum wire to hang the heated electrolytic cell upside down in the heating furnace, place a larger silicon carbide crucible around the electrolytic cell to protect the heating furnace, and heat the sample to 1500 ° C and keep it for 6 h according to the above heating steps. The sample in the electrolytic cell is fully flowed out of the electrolytic cell, and a niobium-titanium carbide corrosion-resistant layer is formed on the inner surface of the silicon carbide electrolytic cell in situ, and the schematic diagram of heating is shown in Figure 3.

The electrolytic cell was cut along the axial direction, and the scanning electron microscope inspection was carried out. The results are shown in Figures 4 and 5. From the scanning electron microscope results, relatively dense niobium carbide-titanium carbide has been formed on the inner surface of the silicon carbide electrolytic cell. Erosion-resistant protective layer: After the electrolyte and the electrolytic cell are fully contacted for 24 hours, a relatively dense niobium carbide-titanium carbide erosion-resistant protective layer with a thickness of about 95 μm has been formed through the above-mentioned chemical reaction.

Example 2

The raw materials CaO-SiO ₂ -CaF ₂ -CeO ₂ -TiO ₂ -Nb ₂ O ₅ -Fe ₂ O ₃ used in the examples are shown in Table 2

Table 2 CaO-SiO ₂ -CaF ₂ -CeO ₂ -TiO ₂ -Nb ₂ O ₅ -Fe ₂ O ₃ raw material components used in Example 2

Element CaO SiO₂ CaF₂ CeO₂ TiO₂ Nb₂O₅ Fe₂O₃ Content (wt%) 5 10 5 5 25 25 25

A total of 5g of powdered raw materials were weighed according to the proportion of each oxide, and the powdered raw materials were compressed into discs with a diameter of 30mm using a powder tablet machine, the pressure was set to 10Mpa, and the pressure holding time was 15min;

The obtained wafer is put into the silicon carbide electrolytic cell, and the silicon carbide electrolytic cell with the wafer is placed in a heating furnace for heating (the heating schematic diagram is shown in Figure 2). The heating rate of min is increased from room temperature to 500 °C, and then the temperature is increased from 500 °C to 1450 °C at a heating rate of 8 °C/min, and the temperature is kept at 1450 °C for 48 hours. After cooling in the furnace, the electrolytic cell is taken out;

Use molybdenum wire to hang the heated electrolytic cell upside down in the heating furnace, place a larger size silicon carbide crucible around the electrolytic cell to protect the heating furnace, and heat the sample to 1450 ° C and keep it for 6 h according to the above heating steps. The sample in the electrolytic cell is fully flowed out of the electrolytic cell, and a niobium-titanium carbide corrosion-resistant layer is formed on the inner surface of the silicon carbide electrolytic cell in situ, and the schematic diagram of heating is shown in Figure 3.

The electrolytic cell was cut along the axial direction, and the scanning electron microscope inspection was carried out. From the results of the scanning electron microscope, a relatively dense niobium carbide-titanium carbide corrosion-resistant protective layer has been formed on the inner surface of the silicon carbide electrolytic cell, oxide-fluorine After the electrolyte formed by the melting of the compound melt is fully in contact with the electrolytic cell for 24 hours, a relatively dense niobium carbide-titanium carbide corrosion-resistant protective layer with a thickness of about 150 μm has been formed through the above-mentioned chemical reaction.

Example 3

The raw materials CaO-SiO ₂ -CaF ₂ -CeO ₂ -TiO ₂ -Nb ₂ O ₅ -Fe ₂ O ₃ used in the examples are shown in Table 3

Table 3 CaO-SiO ₂ -CaF ₂ -CeO ₂ -TiO ₂ -Nb ₂ O ₅ -Fe ₂ O ₃ raw material components used in Example 3

Element CaO SiO₂ CaF₂ CeO₂ TiO₂ Nb₂O₅ Fe₂O₃ Content (wt%) 10 40 30 12.5 2.5 2.5 2.5

A total of 1.5g of powder raw materials were weighed according to the proportion of each oxide, and the powder raw materials were compressed into discs with a diameter of 10mm using a powder tablet machine, the pressure was set to 3Mpa, and the pressure holding time was 2min;

The obtained wafer is put into the silicon carbide electrolytic cell, and the silicon carbide electrolytic cell with the wafer is placed in a heating furnace for heating (the heating schematic diagram is shown in Figure 2). The heating rate of min is increased from room temperature to 1400 °C, and then the temperature is increased from 1400 °C to 1600 °C at a heating rate of 5 °C/min, and the temperature is kept at 1600 °C for 12 hours. After cooling in the furnace, the electrolytic cell is taken out;

Use molybdenum wire to hang the heated electrolytic cell upside down in the heating furnace, place a larger size silicon carbide crucible around the electrolytic cell to protect the heating furnace, and heat the sample to 1600 ° C and keep it for 6 h according to the above heating steps. The sample in the electrolytic cell is fully flowed out of the electrolytic cell, and a niobium-titanium carbide corrosion-resistant layer is formed on the inner surface of the silicon carbide electrolytic cell in situ, and the schematic diagram of heating is shown in Figure 3.

The electrolytic cell was cut along the axial direction, and the scanning electron microscope inspection was carried out. From the results of the scanning electron microscope, a relatively dense niobium carbide-titanium carbide corrosion-resistant protective layer has been formed on the inner surface of the silicon carbide electrolytic cell, and the electrolyte and the electrolytic cell have been formed. After being fully contacted for 24 hours, a relatively dense niobium carbide-titanium carbide corrosion-resistant protective layer with a thickness of about 40 μm has been formed by the above-mentioned chemical reaction.

Comparative Example 1

The raw materials in Example 1 were replaced with the components shown in Table 4 (without Fe ₂ O ₃ and Nb ₂ O ₅ ), and an erosion-resistant layer was prepared on the inner surface of the silicon carbide electrolytic cell according to the scheme of Example 1.

Table 4 Composition of raw materials used in Comparative Example 1

Element CaO SiO₂ CaF₂ CeO₂ TiO₂ Content (wt%) 17.2 46.7 22.2 5.6 8.3

In the present invention, the obtained silicon carbide electrolytic cell is detected by scanning electron microscope, and the results are shown in Figs.

Comparative Example 2

The raw materials in Example 1 were replaced with the components shown in Table 5 (ie, no Fe ₂ O ₃ and TiO ₂ ), and an erosion-resistant layer was prepared on the inner surface of the silicon carbide electrolytic cell according to the scheme of Example 1.

The raw material composition that table 5 comparative example 2 adopts

Element CaO SiO₂ CaF₂ CeO₂ Nb₂O₅ Content (wt%) 17.7 48 22.9 5.7 5.7

In the present invention, the obtained silicon carbide electrolytic cell is tested by scanning electron microscope, and the results are shown in Figs.

By comparing the SEM images of niobium carbide and titanium carbide erosion protection layer and the main components, it is found that the niobium carbide-titanium carbide erosion protection layer formed when Fe ₂ O ₃ , TiO ₂ and Nb ₂ O ₅ coexist is more compact, and the main components are mainly It is niobium carbide and titanium carbide, and the niobium carbide or titanium carbide corrosion protection layer that exists alone contains more salts, and the corrosion protection effect is not as good as that of niobium carbide-titanium carbide corrosion protection layer.

Comparative Example 3

The raw materials in Example 1 were replaced with the components shown in Table 6 (ie, no Fe ₂ O ₃ ), and an erosion-resistant layer was prepared on the inner surface of the silicon carbide electrolytic cell according to the scheme of Example 1.

The raw material composition that table 6 comparative example 3 adopts

Element CaO SiO₂ CaF₂ CeO₂ Nb₂O₅ TiO₂ Content (wt%) 16.2 44.2 21.1 5.3 5.3 7.9

In the present invention, the obtained silicon carbide electrolytic cell is inspected by scanning electron microscope, and the result is shown in FIG. 10 . In this comparative example, titanium carbide-niobium carbide and an etched layer doped with partial salt are obtained.

Example 4

Table 7 CaO-SiO ₂ -CaF ₂ -CeO ₂ -TiO ₂ -Nb ₂ O ₅ -Fe ₂ O ₃ raw material components used in Example 4

Element CaO SiO₂ CaF₂ CeO₂ TiO₂ Nb₂O₅ Fe₂O₃ Content (wt%) 15.5 42 20 5 7.5 5 5

A total of 3.21g of powder raw materials were weighed according to the proportion of each oxide, and the powder raw materials were compressed into a disc with a diameter of 13mm using a powder tablet machine, the pressure was set to 5Mpa, and the pressure holding time was 5min;

The obtained wafer is placed in the silicon carbide electrolytic cell, and the silicon carbide electrolytic cell with the wafer is placed in a heating furnace for heating (the heating schematic diagram is shown in Figure 2). The heating rate of min is increased from room temperature to 1000 °C, and then the temperature is increased from 1000 °C to 1500 °C at a heating rate of 5 °C/min, and the temperature is kept at 1500 °C for 24 hours to form an erosion protection layer. Repeat the above heating and holding steps and carry out five experiments to test the performance of the erosion protection layer;

After the experiment, the electrolytic cell was cut along the axis direction, and the scanning electron microscope inspection was carried out. The results are shown in Figure 11. From the scanning electron microscope results, the thickness of the corrosion-resistant layer on the inner surface of the silicon carbide electrolytic cell is about 100 μm. The erosion protection layer thickness of Example 1 did not change much.

Comparative Example 4

Table 8 CaO-SiO ₂ -CaF ₂ -CeO ₂ -TiO ₂ -Nb ₂ O ₅ -Fe ₂ O ₃ raw material components used in Comparative Example 4

Element CaO SiO₂ CaF₂ CeO₂ Fe₂O₃ Content (wt%) 17.7 48 22.9 5.7 5.7

A total of 3.21g of powder raw materials were weighed according to the proportion of each oxide, and the powder raw materials were compressed into a disc with a diameter of 13mm using a powder tablet machine, the pressure was set to 5Mpa, and the pressure holding time was 5min;

The obtained wafer is placed in the silicon carbide electrolytic cell, and the silicon carbide electrolytic cell with the wafer is placed in a heating furnace for heating (the heating schematic diagram is shown in Figure 2). The heating rate of min is increased from room temperature to 1000 °C, and then the temperature is increased from 1000 °C to 1500 °C with a heating rate of ₅ °C/ _min , and the temperature is kept at 1500 °C for ₂₄ hours. The corrosion protection layer could not be formed, except that other experimental conditions were the same.

Fig. 12 is the inspection diagram of the crucible without the corrosion protection layer after the experiment. It is found that when there is no corrosion protection layer, the corrosion thickness of the electrolyte to the electrolytic cell can reach 600-1200 μm.

After comparison, it can be seen that the in-situ formation of the corrosion-resistant protective layer on the inner surface of the electrolytic cell effectively solves the problem of electrolytic extraction with the CaO-SiO ₂ -CaF ₂ -REO-TiO ₂ -Nb ₂ O ₅ -Fe ₂ O ₃ system as the electrolyte. Electrolyte erosion of electrolytic cells in metal processes.

The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art who is familiar with the technical scope disclosed by the present invention can easily think of changes or substitutions. All should be included within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims (8)

1. An erosion-resistant silicon carbide container, comprising a silicon carbide container base and a niobium-titanium carbide erosion-resistant coating adsorbed on the inner surface of the silicon carbide container base, wherein the chemical composition of the niobium-titanium carbide erosion-resistant coating includes niobium carbide and carbide titanium. 2 . The corrosion-resistant carbonization container according to claim 1 , wherein the thickness of the niobium-titanium carbide corrosion-resistant coating is 40-150 μm. 3 . 3. The corrosion-resistant silicon carbide container according to claim 1 or 2, wherein the silicon carbide container base is a silicon carbide electrolytic cell. 4. the preparation method of the corrosion-resistant silicon carbide container described in any one of claim 1～3, comprises the following steps: The raw material for preparing the niobium-titanium carbide corrosion-resistant coating in the corrosion-resistant silicon carbide container is placed in the silicon carbide container base, and the raw material includes the following components in mass percentage: 5-30% CaO, 10-50 % SiO ₂ , 5~40% CaF ₂ , 0~20% CeO ₂ , 2.5~25% TiO ₂ , 2.5~25% Nb ₂ O ₅ and 2.5~25% Fe ₂ O ₃ ; In a protective atmosphere, the silicon carbide container base containing the raw material is heated and then kept warm. During the process of heating and heat preservation, the raw material changes into a liquid phase and reacts with the inner surface of the silicon carbide container base. , in-situ high temperature reaction in the silicon carbide container base to form a niobium-titanium carbide corrosion-resistant coating, and the temperature of the heat preservation is 1300-1800 °C. 5. preparation method according to claim 4, is characterized in that, described heating temperature rise comprises continuous temperature rise or subsection temperature rise, and the temperature rise rate of described continuous temperature rise is 1～50 ℃/min; The step-by-step heating includes the following steps: heating up to an intermediate temperature at a first heating rate, the first heating rate is 1-50°C/min, and the intermediate temperature is 500-1300°C; The temperature is raised from the intermediate temperature to the holding temperature at a second heating rate, the second heating rate is 1-50°C/min, and the holding temperature is 1300-1800°C. 6. preparation method according to claim 4 or 5 is characterized in that, the time of described insulation is 12～48h. 7 . The preparation method according to claim 4 , wherein after the heat preservation, the method further comprises: cooling the silicon carbide container obtained by the heat preservation and then inverting the container, and repeating the heating and the heat preservation. 8 . 8. The application of the corrosion-resistant silicon carbide container according to any one of claims 1 to 3 in corrosion-resistant molten fluoride-oxide.

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