A ceramic / metal interface bonding method based on binder jetting

Abstract

The application belongs to the technical field of casting, and discloses a ceramic / metal interface bonding method based on binder jetting forming, which comprises the following steps: S1, designing a pourable hollow ceramic shell; S2, obtaining a preliminary blank by using a binder jetting forming technology for 3D printing, and then solidifying, vacuum infiltrating, drying, and defatting and sintering to obtain a ceramic shell; S3, depositing an intermediate layer containing a metal material on the inner surface of the ceramic shell; and S4, filling a ferrous metal liquid into the ceramic shell in which the intermediate layer is deposited by using a casting method, so that a casting with ceramic / metal interface bonding can be obtained after cooling. By using the binder jetting forming technology, the ceramic shell is quickly and directly prepared, the wettability of the ceramic and the metal is improved by coating the intermediate layer, and the integration forming of the ceramic / metal part is realized by combining the casting technology, so that the wear resistance and corrosion resistance of the metal are improved, and the service performance and service life of the part are greatly improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of casting, and more particularly relates to a ceramic / metal interface bonding method based on binder jetting forming. BACKGROUND

[0002] With the improvement of technology, the working environment of industrial equipment is more complex and diversified. Metal parts are widely used in various industrial equipment and structures. With the improvement of use requirements and the expansion of working environment, the performance of single metal usually cannot meet the needs of extreme and harsh working conditions. To meet the wear and corrosion resistance requirements of mechanical parts, using ceramic / metal materials is a feasible solution. The combination of metal and ceramic can effectively retain the toughness of metal materials and the wear and corrosion resistance of ceramic materials, making it an ideal material for mechanical parts.

[0003] Patent document CN114988918A discloses a surface metallization method of alumina ceramic. Metal powder, additives and organic carriers are mixed to form a metallization slurry. The metallization slurry is printed onto the alumina ceramic substrate using a screen, and then dried and sintered in a gas protection environment to obtain a surface metallized alumina ceramic. The preparation process is complex, and only simple structure ceramic / metal combination can be achieved (because for complex structures, there are often areas that cannot be covered by screen printing, limiting the application).

[0004] Patent document CN102978616A discloses a centrifugal self-propagating method for preparing an alumina coating on the surface of a steel plate. Nickel-coated aluminum powder is sprayed onto the outer side of a roughened steel plate using a flame powder spray gun, and then an alumina coating is coated on the surface of the steel plate through an aluminum thermal reaction using a centrifugal turntable and aluminum thermal welding agent provided by the device. Only simple plate structure ceramic / metal combination can be achieved, which has great limitations (because for complex structures, there are often areas that cannot be sprayed by the spray gun, limiting the application).

[0005] There are large differences in physical, chemical and mechanical properties between metal and ceramic, and the interface wettability is poor. Although the above methods can achieve the combination of metal and ceramic, the process is complex and the cost is high, which makes it difficult to meet the coating preparation of complex parts inner cavity and flow channel. Therefore, in order to realize the good combination of ceramic / metal interface under complex shape, a ceramic / metal part preparation method with high production efficiency and simple preparation process needs to be explored. SUMMARY

[0006] In view of the above defects or improvement needs of the prior art, the purpose of the present application is to provide a ceramic / metal interface bonding method based on binder jetting forming, which quickly and directly prepares a ceramic shell through a binder jetting forming technology, then improves the wettability of the ceramic and the metal through an intermediate layer coating, and realizes the integrated forming of the ceramic / metal part through a casting technology, so that the obtained casting with ceramic / metal interface bonding has improved wear resistance and corrosion resistance of the metal compared with the pure metal casting, greatly improves the performance and service life of the part, and is also a major technical breakthrough in the manufacturing of mechanical parts.

[0007] To achieve the above-mentioned purpose, according to the present application, a ceramic / metal interface bonding method based on binder jetting forming is provided, characterized in that it comprises the following steps:

[0008] S1 Based on 3D printing, a hollow ceramic shell that can be cast is designed according to the structure of the target casting;

[0009] S2 The hollow ceramic shell is manufactured into a green body by using a binder jetting forming technology, and then is sequentially subjected to solidification, vacuum impregnation, drying and debinding sintering, so that the ceramic shell is obtained; wherein the debinding sintering is used for sintering and removing the binder;

[0010] S3 An intermediate layer containing a metal material is deposited on the inner surface of the ceramic shell by using vacuum impregnation coating or chemical plating;

[0011] S4 An iron-based metal liquid is filled into the ceramic shell with the deposited intermediate layer by using a casting method, and is subjected to temperature control solidification and heat preservation treatment, so that the casting with ceramic / metal interface bonding is obtained after cooling.

[0012] As a further preferred embodiment of the present application, step S2 specifically mixes the ceramic powder to be printed with a sintering aid MnO2 in advance, and then 3D prints the obtained mixture into a green body by using a binder jetting forming technology; wherein the mass fraction of the sintering aid MnO2 in the mixture is 6% to 10%, and the particle size of the sintering aid and the ceramic powder is between 500 to 2000 meshes; preferably, the ceramic powder is an alumina ceramic powder;

[0013] In step S2, the solidification temperature used for solidification is 160 to 220℃, and the solidification time is 2 to 3h;

[0014] The impregnation liquid used for the vacuum impregnation is TiO2 sol, the solid content is 20 to 30wt%, the impregnation time is 90 to 120s, and the impregnation vacuum degree is 20 to 30KPa;

[0015] The process parameters of the defatted sintering are as follows: increasing the temperature from room temperature to 640-660℃ at a heating rate of 2-4℃ / min, keeping the temperature for 60-90min; then increasing the temperature to 950-1050℃ at a heating rate of 2-4℃ / min; then increasing the temperature to 1400-1450℃ at a heating rate of 1-2℃ / min, keeping the temperature for 2-4h; finally, cooling to room temperature in the furnace.

[0016] As a further preferred embodiment of the present application, step S3 is specifically using a vacuum dip-coating method, and the coating is a mixture of aggregate and coating binder; wherein the coating binder is a silica sol with a solid content of 20-40wt%; the aggregate is a metal element powder with a particle size of 1000-1200 mesh and a melting point of 1400-1800℃; the mass percentage of the aggregate in the coating is 40-60%; preferably, the metal element powder is nickel powder, chromium powder or titanium powder.

[0017] Step S3 specifically comprises the following sub-steps:

[0018] S3.1 stirring the coating with a high-speed stirrer at a rotating speed of 1500-2000r / min for 10-15min, and then performing vacuum dip-coating; the vacuum dip-coating is performed at a vacuum degree of 20-40KPa, and the dip-coating time is 20-40s;

[0019] S3.2 placing the ceramic shell after vacuum dip-coating in a vacuum environment with a vacuum degree of 20-40KPa for 1-2h to completely precipitate the bubbles in the coating;

[0020] S3.3 drying the ceramic shell obtained in step S3.2 at a temperature of 40-60℃ for 18-24h;

[0021] S3.4 performing sintering treatment on the ceramic shell obtained in step S3.3 to sinter the coating; the process parameters of the sintering treatment are as follows: increasing the temperature from room temperature to 1200-1300℃ at a heating rate of 2-4℃ / min, keeping the temperature for 30-60min, and finally cooling to room temperature in the furnace.

[0022] As a further preferred embodiment of the present application, step S3 is specifically using a chemical nickel plating method, and the corresponding intermediate layer is a metal nickel layer.

[0023] Step S3 specifically comprises the following sub-steps:

[0024] S3-1 performing ultrasonic cleaning on the ceramic shell using anhydrous ethanol as the cleaning agent for 15-30min, and then replacing the cleaning agent with deionized water to perform ultrasonic cleaning on the ceramic shell for 5-20min, so as to ensure that the stains penetrated into the ceramic pores are removed;

[0025] S3-2 puts the ceramic shell treated in step S3-1 into a NaOH solution with a concentration of 500-800 g / L, and roughens the ceramic shell at 40-60 ℃ for 30-60 min, then repeatedly ultrasonic cleans the ceramic shell with deionized water as a cleaning agent for 20-40 min each time, and measures the pH value of the solution after each cleaning until the pH value is reduced to 7.4-7.6, so as to ensure that the roughening solution in the surface and the ceramic pores is completely removed;

[0026] S3-3 immerses the ceramic shell treated in step S2-2 into a sensitization solution for 10-25 min for sensitization treatment, then rinses the ceramic shell under flowing deionized water for 20-30 s after the sensitization;

[0027] S3-4 immerses the ceramic shell treated in step S3-3 into an activation solution for 15-25 min for activation treatment, then rinses the ceramic shell under flowing deionized water for 20-30 s after the activation, and then puts the obtained ceramic shell into a NaH2PO2 solution with a concentration of 18-30 g / L for reduction for 3-8 min;

[0028] S3-5 puts the ceramic shell treated in step S3-4 into a plating solution, and performs electroless plating at a temperature of 60-80 ℃; in the process of electroless plating, the plating solution is stirred at a constant speed, and the plating time is 20-40 min;

[0029] S3-6 takes out the ceramic shell after the nickel plating is completed, washes the ceramic shell, and then heats the ceramic shell at 180-250 ℃ for 40-60 min, and then cools the ceramic shell in the furnace.

[0030] As a further preferred embodiment of the present application, in step S4, the ferrous metal liquid is a 65Mn spring steel liquid;

[0031] The casting is specifically gravity casting, and the pouring temperature used is 1600-1700 ℃; or the casting is specifically vacuum suction casting, and the pouring temperature used is 1550-1650 ℃, and the negative pressure used is -0.05 to -0.1 MPa.

[0032] As a further preferred embodiment of the present application, in step S4, the ceramic shell is preheated at 1200 ℃ or above for 30-60 min before being poured;

[0033] The temperature control solidification and heat preservation treatment specifically comprises the following steps: after the pouring is completed, the workpiece is cooled at a preset rate, and the temperature is kept at 1600-1200 ℃, and the temperature is kept for 1-2 h after decreasing by 100-200 ℃ each time, until the temperature is reduced to 700-800 ℃, and finally the workpiece is cooled to room temperature in the furnace; the preset rate is specifically 1-2 ℃ / min.

[0034] Compared with the prior art, the present application is prepared by the binder jetting forming technology, and the ceramic shell is directly and quickly prepared, and then the intermediate layer is coated to improve the wettability of the ceramic and the metal, and the casting technology is combined to realize the integrated forming of the ceramic / metal part. The obtained casting with the ceramic / metal interface bonding has good interface bonding.

[0035] The method of the present application is suitable for complex components as long as a pourable hollow ceramic shell can be formed, and is suitable for various complex parts with complex inner cavity and flow channel shape. Moreover, the present application realizes 3D printing through the binder jetting forming technology. On the one hand, the formed structure obtained by the binder jetting forming does not need support, and the shape of the printed shell material is more free, which is suitable for complex structures. On the other hand, the high open porosity of the ceramic prepared by the binder jetting forming also provides convenience for the infiltration of the metal into the ceramic shell. Unlike the casting method of the ceramic / metal integrated part based on the layered extrusion forming reported by the research group of the present inventors (see Chinese Patent ZL 201910691963.3), the binder jetting forming technology used in the present application has greater technical flexibility in forming ceramic shells, and can design the ceramic shell more freely without support, and can prepare large-size parts. Moreover, the intermediate layer preparation methods such as dip coating and chemical plating used in the present application are more suitable for complex ceramic inner cavities, and have greater technical application potential.

[0036] Specifically, the present application can achieve the following beneficial effects:

[0037] (1) The method of the present application breaks through the design limit of the existing ceramic / metal parts by the binder jetting forming technology, and can form any complex ceramic shell and combine the intermediate layer preparation and metal liquid pouring to realize the integrated forming of the ceramic / metal part, and the process is simple and has strong operability.

[0038] (2) The method of the present application is based on vacuum dip coating or chemical plating to prepare an intermediate transition layer (i.e., an intermediate layer) on the surface of the ceramic (such as alumina ceramic), which can coat the transition layer on the complex inner cavity flow channel surface, and the coating is uniform and well combined, and the powder selected for the coating can be preferably nickel powder, chromium powder, titanium powder and other metals with melting points of 1400-1800℃, which has universality and can meet the demand for preparing metal, ceramic and other coatings on the surface of the ceramic.

[0039] (3) The method of the present application is suitable for various casting methods such as gravity casting, vacuum suction casting, etc., and can be flexibly selected according to actual needs. For example, low-pressure casting methods such as vacuum suction casting are particularly suitable for ceramic / metal thin-walled parts with a wall thickness of not more than 1mm, and gravity casting is suitable for ordinary ceramic / metal castings without wall thickness requirements. BRIEF DESCRIPTION OF DRAWINGS

[0040] Figure 1 Flow chart of the method for bonding iron-based metal and alumina ceramic based on the binder jetting forming technology in the embodiment of the present application.

[0041] Figure 2 Cross-sectional view of the sample involving the coating of the metal transition layer on the surface of the alumina ceramic in Example 1. In the figure, the number 1 corresponds to the alumina substrate region, and the number 2 corresponds to the metal transition layer (i.e., the intermediate layer containing metal materials).

[0042] Figure 3 Contact angle of the alumina ceramic with the iron-based metal liquid before and after the addition of the transition layer Cr. In the figure, Figure 3 (a) in FIG. 1 is a comparison chart of the contact angle of the alumina ceramic with the iron-based metal liquid before and after the addition of the transition layer Cr, which is obtained by using the sessile drop method (in the figure, the legend "Cr coating" corresponds to the alumina ceramic with the transition layer Cr, and the legend "alumina ceramic" corresponds to the alumina ceramic without the transition layer); Figure 3 (b) in FIG. 1 is an optical photo of the initial state of the alumina ceramic with the iron-based metal liquid without the transition layer; Figure 3 (b1) in FIG. 1 is an optical photo of the steady state of the alumina ceramic with the iron-based metal liquid without the transition layer; Figure 3 (c) in FIG. 1 is an optical photo of the initial state of the alumina ceramic with the iron-based metal liquid with the transition layer Cr; Figure 3 (c1) in FIG. 1 is an optical photo of the steady state of the alumina ceramic with the iron-based metal liquid with the transition layer Cr.

[0043] Figure 4 Interface structure diagram of the alumina ceramic without the transition layer after pouring with the iron-based metal liquid involved in Comparative Example 1.

[0044] Figure 5 Interface structure and element distribution of the alumina ceramic with the Cr transition layer after pouring with the iron-based metal liquid involved in Example 1. DETAILED DESCRIPTION

[0045] In order to make the objectives, technical solutions, and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and should not be used to limit the present application. In addition, the technical features involved in each embodiment of the present application described below can be combined with each other as long as they do not conflict with each other.

[0046] In general, the ceramic / metal interface bonding method based on binder jetting forming in the present application comprises the following steps: (1) designing a castable hollow complex ceramic shell according to requirements; (2) mixing ceramic powder with sintering aids and sieving and drying; (3) preparing a hollow ceramic shell body by using a binder jetting forming technology, and performing solidification, vacuum infiltration, drying and debinding sintering; (4) preparing an intermediate transition layer, coating the obtained ceramic shell with the intermediate transition layer, drying and sintering; (5) using a casting process (such as gravity casting, vacuum suction casting and the like), filling a ferrous metal liquid into the ceramic shell coated with the transition layer, and performing temperature control solidification and heat preservation treatment, and finally realizing good interface bonding.

[0047] The following are specific embodiments:

[0048] Embodiment 1

[0049] The present embodiment provides a ferrous metal and alumina ceramic bonding method based on a binder jetting forming technology, specifically comprising the following steps:

[0050] First, a binder jetting forming technology is used to manufacture a hollow ceramic shell. Specifically, the preparation of the ceramic shell comprises the following steps:

[0051] (1) 6wt% of 500 mesh MnO2 sintering aid is added to 500 mesh alumina ceramic powder, and an automatic powder mixer is used for mixing for 4h;

[0052] (2) The binder jetting forming technology is used to realize the overall forming of the ceramic shell, and the initial blank is solidified at 160℃ for 2h. The binder used in the binder jetting forming technology is a phenolic resin binder, and the detailed parameter conditions used in the binder jetting forming are: layer height is 0.15mm, and binder saturation is 100%.

[0053] (3) The initial blank after solidification is vacuum infiltrated with TiO2 sol with a solid content of 20%, the infiltration time is 90s, and the infiltration vacuum degree is 20KPa, so as to strengthen the strength of the blank;

[0054] (4) The ceramic shell after infiltration is dried at 60℃ for 24h to completely dehydrate;

[0055] (5) The ceramic shell after infiltration and drying is debinding sintered, and the sintering parameters are set as follows: the heating rate is 2℃ / min from room temperature to 640℃, the temperature is kept for 60min, then the heating rate is 2℃ / min to 950℃, the decreasing heating rate is 1℃ / min to 1400℃, the temperature is kept for 2h, and finally the temperature is cooled to room temperature in the furnace;

[0056] Second step, the intermediate layer is prepared by vacuum dip-coating. The binder of the coating is 20% solid content silica sol, and the aggregate is chromium powder with particle size of 1000 mesh, and the aggregate accounts for 40% by weight. The preparation process includes the following sub-steps:

[0057] (1) The coating is stirred by a high-speed mixer at a speed of 1500 r / min for 10 min, and then dip-coated at a vacuum degree of 20 KPa for 20 s;

[0058] (2) After dip-coating, the ceramic shell is placed in a vacuum tank at a vacuum degree of 20 KPa for 1 h to ensure that the bubbles in the coating are completely precipitated;

[0059] (3) The ceramic shell is dried in a drying box at a temperature of 40℃ for 18 h;

[0060] (4) After drying, the process parameters for sintering the coating are as follows: the heating rate is 3℃ / min, the temperature is raised from room temperature to 1200℃, and the temperature is maintained for 30 min, and finally the furnace is cooled to room temperature. The thickness of the obtained coating is 200 μm.

[0061] Third step, the sintered ceramic shell with coating is buried in silica sand, the sprue and the riser are reserved, preheated to 1200℃, and maintained for 30 min. The pouring temperature is 1600℃. After pouring, the workpiece is maintained at 1500℃, 1400℃, 1300℃ and 1200℃ for 1 h respectively, the intermediate cooling rate is 1℃ / min, and then the temperature is decreased to 700℃ at a rate of 1℃ / min, and finally the furnace is cooled to room temperature.

[0062] Fourth step, after the casting is cooled, it is taken out, and the pouring system part is cut off to obtain an alumina / iron composite casting.

[0063] The sample prepared in the second step of Example 1 is subjected to SEM characterization, and the results are shown in Figure 2 From the results, it can be seen that the Cr coating after sintering is well combined with the alumina ceramic matrix without obvious cracks, and the coating is dense and uniform, which indicates that the dip-coating and sintering effect is good.

[0064] In addition, the sample prepared in the fourth step of Example 1 is subjected to SEM characterization, and the results are shown in Figure 5 From the results, it can be seen that the ceramic / metal sample after gravity casting with the addition of Cr intermediate layer has no obvious cracks at the bonding interface, and the bonding is tight. Under the face scanning analysis, the existence of the Cr intermediate layer can be observed, which proves the significant effect of the intermediate layer on the bonding of the ceramic / metal interface.

[0065] Comparative Example 1

[0066] Comparative Example 1 does not contain an intermediate layer, and the preparation process includes the following steps:

[0067] First step, the hollow ceramic shell is manufactured by using the binder jetting technology, and the preparation of the ceramic shell comprises the following steps:

[0068] (1) 6wt% of 500 mesh MnO2 sintering aid is added into 500 mesh alumina ceramic powder, and the automatic powder mixer is used for mixing for 4h;

[0069] (2) The whole forming of the ceramic shell is realized by using the binder jetting technology, and the initial blank is solidified at 160℃ for 2h; the binder used in the binder jetting technology is a phenolic resin binder, and the detail parameter condition used in the binder jetting is that the layer height is 0.15mm, and the binder saturation is 100%.

[0070] (3) The initial blank after solidification is vacuum infiltrated with TiO2 sol with a solid content of 20%, the infiltration time is 90s, and the infiltration vacuum degree is 20KPa, so as to strengthen the strength of the blank;

[0071] (4) The ceramic shell after infiltration is dried at 60℃ for 24h until completely dehydrated;

[0072] (5) The ceramic shell after infiltration and drying is subjected to debinding and sintering, and the sintering parameters are set as follows: the heating rate is 2℃ / min from room temperature to 640℃, the temperature is kept for 60min, then the heating rate is 2℃ / min to 950℃, the decreasing heating rate is 1℃ / min to 1400℃, the temperature is kept for 2h, and finally the temperature is cooled to room temperature in the furnace;

[0073] Second step: the sintered ceramic shell is buried in silica sand, the sprue and the riser are reserved, preheated to 1200℃, kept for 30min, the pouring temperature is 1600℃, after pouring, the workpiece is kept at 1500℃, 1400℃, 1300℃ and 1200℃ for 1h, the intermediate cooling rate is 1℃ / min, then the temperature is decreased to 700℃ at a rate of 1℃ / min, and finally the temperature is cooled to room temperature in the furnace.

[0074] Third step, after the casting is cooled, it is taken out, and the pouring system part is cut off, so as to obtain the alumina / iron composite casting.

[0075] The sample prepared in the third step of Comparative Example 1 is subjected to SEM characterization, and the results are shown in Figure 4 From which it is not difficult to see that the ceramic / metal gravity pouring interface without the intermediate layer has obvious cracks, and the interface front is seriously oxidized, which has no application value.

[0076] The sample prepared in the first step of Comparative Example 1 and the sample prepared in the second step of Example 1 are subjected to surface contact angle test with iron-based metal liquid, and the results are shown in Figure 3As shown, it can be seen from the figure that the contact angle of the sample with the Cr interlayer is reduced from 98.9° to 78.4° compared with the sample without the interlayer, i.e. the interface is changed from non-wetting (contact angle > 90°) to wetting (contact angle < 90°), which also proves the important role of the interlayer for the ceramic / metal interface bonding.

[0077] Example 2

[0078] The present embodiment provides a method for bonding iron-based metal and alumina ceramic based on the binder jetting forming technology, which specifically comprises the following steps:

[0079] In the first step, the binder jetting forming technology is used to manufacture the hollow ceramic shell. Specifically, the preparation of the ceramic shell comprises the following steps:

[0080] (1) 8wt% of 1250 mesh MnO2 sintering aid is added to 1250 mesh alumina ceramic powder, and an automatic powder mixer is used for mixing for 4h;

[0081] (2) The binder jetting forming technology is used to realize the overall forming of the ceramic shell, and the initial blank is cured at 190°C for 2.5h; the binder used in the binder jetting forming technology is a phenolic resin binder, and the detailed parameter conditions used in the binder jetting forming are as follows: layer height is 0.1mm, and binder saturation is 120%.

[0082] (3) The initial blank after curing is vacuum infiltrated with TiO2 sol with a solid content of 25%, the infiltration time is 105s, and the infiltration vacuum degree is 25KPa;

[0083] (4) The ceramic shell after infiltration is dried at 60°C for 24h until completely dehydrated;

[0084] (5) The ceramic shell after infiltration and drying is subjected to debinding and sintering, and the sintering parameters are set as follows: the heating rate is 3°C / min from room temperature to 650°C, the temperature is kept for 75min, then the heating rate is 3°C / min to 1000°C, the decreasing heating rate is 1.5°C / min to 1425°C, the temperature is kept for 3h, and finally the temperature is cooled to room temperature in the furnace;

[0085] In the second step, the interlayer is prepared by vacuum dipping coating, the binder of the coating is 30% solid content of silica sol, the aggregate is titanium powder with a particle size of 1200 mesh, and the aggregate accounts for 60wt%; the preparation process comprises the following sub-steps:

[0086] (1) The coating is stirred by a high-speed stirrer at a speed of 2000r / min for 15min, then dipped, the vacuum degree for dipping is 40KPa, and the dipping time is 40s;

[0087] (2) After dip-coating, the ceramic shell is placed in a vacuum tank to ensure that the bubbles in the coating are completely released by placing it at a vacuum degree of 40 KPa for 2 h;

[0088] (3) The ceramic shell is dried in a drying oven at a temperature of 60 °C for 24 h;

[0089] (4) After drying, the process parameters for sintering the coating are as follows: the heating rate is 3 °C / min, the temperature is raised to 1300 °C, the holding time is 60 min, and finally the furnace is cooled to room temperature. The thickness of the obtained coating is 250 μm.

[0090] In the third step, the sintered ceramic shell with coating is preheated to 1200 °C in a vacuum chamber, and the holding time is 45 min. The vacuum suction casting is performed at a negative pressure of -0.05 MPa, and the vacuum suction casting is performed using 65Mn spring steel liquid at a pouring temperature of 1550 °C. After pouring, the workpiece is held at 1400 °C and 1200 °C for 1.5 h, respectively, and the intermediate cooling rate is 1.5 °C / min. Then, the temperature is decreased to 750 °C at a rate of 1.5 °C / min, and finally the furnace is cooled to room temperature. In this step, the vacuum chamber is connected to the atmosphere when the temperature is decreased from 1200 °C to 750 °C (i.e., when the temperature in the pouring chamber is below 1200 °C), so that the metal liquid in the riser pipe flows back to the crucible.

[0091] In the fourth step, after the casting is cooled, the pouring system part is cut off to obtain an alumina / iron composite casting.

[0092] Example 3

[0093] The present embodiment provides a method for combining iron-based metal and alumina ceramic based on the binder jet molding technology, which specifically comprises the following steps:

[0094] In the first step, the binder jet molding technology is used to manufacture the hollow ceramic shell. Specifically, the preparation of the ceramic shell comprises the following steps:

[0095] (1) 8 wt% of 1250 mesh MnO2 sintering aid is added to 1250 mesh alumina ceramic powder, and an automatic powder mixer is used for mixing for 4 h;

[0096] (2) The binder jet molding technology is used to realize the overall molding of the ceramic shell, and the initial blank is cured at 190 °C for 2.5 h. The binder used in the binder jet molding technology is a phenolic resin binder, and the detailed parameter conditions for the binder jet molding are as follows: the layer height is 0.1 mm, and the binder saturation degree is 120%.

[0097] (3) The cured initial blank is vacuum infiltrated with TiO2 sol with a solid content of 25%, and the infiltration time is 105 s and the infiltration vacuum degree is 25 KPa;

[0098] (4) The impregnated ceramic shell is dried at 60°C for 24h to complete dehydration;

[0099] (5) The impregnated and dried ceramic shell is subjected to debinding and sintering, with the sintering parameters set as follows: the temperature is raised from room temperature to 660°C at a heating rate of 4°C / min, and then kept for 90min; the temperature is raised to 1050°C at a heating rate of 4°C / min, and then kept for 3h at a reduced heating rate of 2°C / min to 1450°C; finally, the temperature is cooled to room temperature in the furnace;

[0100] The second step is to prepare the intermediate layer by vacuum dipping coating, the binder of the coating is 30% solid content silica sol, and the aggregate is titanium powder with a particle size of 1200 mesh, accounting for 60wt%. The preparation process includes the following sub-steps:

[0101] (1) The coating is stirred by a high-speed stirrer at a speed of 2000r / min for 15min, and then subjected to dipping coating at a vacuum degree of 40KPa for 40s;

[0102] (2) After dipping coating, the ceramic shell is placed in a vacuum tank at a vacuum degree of 40KPa for 2h to ensure that the bubbles in the coating are completely precipitated;

[0103] (3) The ceramic shell is dried in a drying box at a temperature of 60°C for 24h;

[0104] (4) After drying, the process parameters for sintering the coating are as follows: the temperature is raised from room temperature to 1300°C at a heating rate of 4°C / min, and then kept for 60min; finally, the temperature is cooled to room temperature in the furnace, and the obtained coating thickness is 240μm.

[0105] The third step is to place the sintered ceramic shell with coating in a vacuum chamber, preheat to 1200°C, and keep for 45min. The negative pressure used for vacuum suction casting is -0.1MPa, the vacuum suction casting is performed by using 65Mn spring steel liquid with a pouring temperature of 1650°C. After pouring, the workpiece is kept at 1400°C and 1200°C for 1.5h respectively, and the intermediate cooling rate is 1.5°C / min. Then, the temperature is decreased to 750°C at a rate of 1.5°C / min, and finally, the temperature is cooled to room temperature in the furnace. In this step, when the temperature in the pouring chamber decreases to below 1200°C, the vacuum chamber is connected to the atmosphere, and the metal liquid in the riser pipe flows back to the crucible.

[0106] The fourth step is to take out the casting after cooling, and cut off the pouring system part to obtain an alumina / iron composite casting.

[0107] Example 4

[0108] The present embodiment provides a method for combining iron-based metal and alumina ceramic based on binder jetting forming technology, which specifically includes the following steps:

[0109] The first step is to manufacture the hollow ceramic shell by using the binder jetting technology. Specifically, the preparation of the ceramic shell includes the following steps:

[0110] (1) Add 10wt% of 2000 mesh MnO2 sintering aid to 2000 mesh alumina ceramic powder, and mix for 4h using an automatic powder mixer;

[0111] (2) Use the binder jetting technology to realize the overall forming of the ceramic shell, and solidify the green body at 220℃ for 3h; the binder used in the binder jetting technology is a phenolic resin binder, and the detailed parameter conditions used in the binder jetting are: layer height is 0.05mm, and binder saturation is 140%.

[0112] (3) Vacuum infiltrate the solidified green body with 30% TiO2 sol, with an infiltration time of 120s and an infiltration vacuum degree of 30KPa;

[0113] (4) Dry the infiltrated ceramic shell at 60℃ for 24h until completely dehydrated;

[0114] (5) Perform debinding and sintering on the infiltrated and dried ceramic shell, with the sintering parameters set as: increase the temperature from room temperature to 660℃ at a heating rate of 4℃ / min, keep the temperature for 90min, then increase the temperature to 1050℃ at a heating rate of 4℃ / min, decrease the temperature to 1450℃ at a heating rate of 2℃ / min, keep the temperature for 4h, and finally cool down to room temperature in the furnace;

[0115] The second step is to prepare the intermediate layer using chemical nickel plating, including the following sub-steps:

[0116] (1) Put the ceramic shell into an ultrasonic cleaner and clean it with anhydrous ethanol as the detergent for 20min, then replace the deionized water and treat it with ultrasonic waves for 15min, to ensure that the stains infiltrated into the ceramic pores are removed;

[0117] (2) Put the ceramic shell into a NaOH solution with a concentration of 700g / L, and roughen it at 50℃ for 45min, then repeatedly clean it with deionized water for 30min (i.e. 30min each time, repeated multiple times), and measure the pH value of the solution after each cleaning until the pH value drops to 7.5±0.1, to ensure that the roughening solution on the surface and in the ceramic pores is completely removed;

[0118] (3) Soak the roughened ceramic shell in a sensitization solution for 15min for sensitization treatment, and then rinse it in flowing deionized water for 25s;

[0119] (4) The sensitized ceramic body is further soaked in an activation solution for 20 minutes for activation treatment. After soaking, the ceramic is rinsed with flowing deionized water for 25 seconds. To prevent the metal ions remaining on the surface of the activated ceramic shell from contaminating the plating solution, the ceramic shell is placed in a NaH2PO2 solution with a concentration of 24 g / L for reduction for 5 minutes.

[0120] (5) The sensitized and cleaned ceramic shell is placed in a prepared plating beaker, and the beaker is placed in a constant-temperature electric heating water bath to be heated to 70°C for electroless plating, and the plating solution is stirred at a uniform speed. The plating time is 30 minutes. The electroless nickel plating solution in this step is a mixed solution of NiSO4, NaH2PO2, C4H6O5, and C2H4NaO2, wherein the content of NiSO4 is 30 g / L, the content of NaH2PO2 is 30 g / L, the content of C4H6O5 is 10 g / L, and the content of C2H4NaO2 is 7.5 g / L (of course, other commonly used electroless nickel plating solutions can also be used).

[0121] (6) After the nickel plating is completed, the ceramic is taken out, cleaned, and then placed in an electric heating constant-temperature drying box for heat preservation at 220°C for 50 minutes, and the obtained intermediate layer has a thickness of 10 μm.

[0122] (3) The coated ceramic shell is placed in a vacuum chamber and preheated to 1200°C for heat preservation for 60 minutes. The vacuum suction casting is performed at a negative pressure of -0.75 MPa, and the pouring temperature of the 65Mn spring steel liquid is 1600°C. After pouring, the workpiece is heat preserved at 1500°C, 1400°C, 1300°C, and 1200°C for 2 hours, respectively, and the intermediate cooling rate is 2°C / min. Then, the temperature is decreased to 800°C at a rate of 2°C / min, and finally, the workpiece is cooled to room temperature in the furnace. In this step, the vacuum chamber is connected to the atmosphere when the temperature in the pouring chamber decreases to below 1200°C, so that the metal liquid in the riser pipe flows back to the crucible.

[0123] (4) After the workpiece is cooled, it is taken out, and the pouring system part is cut off to obtain an alumina / iron composite casting.

[0124] The above examples are only examples. For example, the process can be adjusted according to the thickness requirement of the intermediate layer. In addition to electroless nickel plating, other electroless plating processes known in the prior art can also be used to form an intermediate layer containing a target metal material (the target metal ions in the plating solution and their concentrations can also be adjusted according to actual requirements).

[0125] It is easy for those skilled in the art to understand that the above description is only a preferred embodiment of the present application, and is not intended to limit the present application. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A ceramic / metal interface bonding method based on binder jetting molding, characterized by, The method comprises the following steps: S1, based on 3D printing, according to the structure of the target casting, designing a hollow ceramic shell that can be cast; S2, using a binder jetting molding technology to 3D print and manufacture the hollow ceramic shell to obtain a green body, and then sequentially performing solidification, vacuum infiltration, drying, and debinding sintering to obtain the ceramic shell; wherein the debinding sintering is used for sintering and removing the binder; S3, using a vacuum dipping coating or chemical plating method to deposit a middle layer containing a metal material on the inner surface of the ceramic shell; S4, using a casting method to fill a ferrous metal liquid into the ceramic shell in which the middle layer is deposited, and after temperature control solidification and heat preservation treatment, a casting with a ceramic / metal interface combination is obtained after cooling; When the step S3 uses the vacuum dipping coating method, the coating is a mixture of aggregate and coating binder; wherein the coating binder is a silica sol with a solid content of 20-40 wt%; the aggregate is a metal element powder with a particle size of 1000-1200 mesh, and the melting point of the metal element is 1400-1800 ℃; the mass percentage of the aggregate in the coating is 40-60%; at this time, the step S3 specifically comprises the following sub-steps: S3.1, stirring the coating with a high-speed stirrer at a speed of 1500-2000 r / min for 10-15 min, and then performing vacuum dipping coating; the vacuum degree of the vacuum dipping coating is 20-40 KPa, and the dipping time is 20-40 s; S3.2, placing the ceramic shell after vacuum dipping coating in a vacuum environment with a vacuum degree of 20-40 KPa for 1-2 h to completely precipitate the bubbles in the coating; S3.3, drying the ceramic shell obtained by the treatment of step S3.2 at a temperature of 40-60 ℃ for 18-24 h; S3.4, performing sintering treatment on the ceramic shell obtained by the treatment of step S3.3 to sinter the coating; the process parameters of the sintering treatment are: increasing the temperature from room temperature to 1200-1300 ℃ at a heating rate of 2-4 ℃ / min, keeping the temperature for 30-60 min, and finally cooling to room temperature with the furnace; When the step S3 uses the chemical nickel plating method, the corresponding obtained middle layer is a metal nickel layer; at this time, the step S3 specifically comprises the following sub-steps: S3-1, using anhydrous ethanol as a wash to ultrasonically clean the ceramic shell for 15-30 min, and then replacing the wash with deionized water to ultrasonically clean the ceramic shell for 5-20 min, to ensure that the stains infiltrated into the ceramic pores are removed; S3-2, placing the ceramic shell after the treatment of step S3-1 into a NaOH solution with a concentration of 500-800 g / L, roughening at 40-60 ℃ for 30-60 min, and then ultrasonically cleaning multiple times with deionized water as a wash, each time for 20-40 min, and measuring the pH value of the solution after each cleaning until the pH value decreases to 7.4-7.6, to ensure that the roughening solution in the surface and ceramic pores is completely removed; S3-3 Soak the ceramic shell treated in step S3-2 in a sensitization solution for 10-25 min for sensitization treatment, and then rinse the sensitized ceramic shell under flowing deionized water for 20-30 s; S3-4 Soak the ceramic shell treated in step S3-3 in an activation solution for 15-25 min for activation treatment, and then rinse the activated ceramic shell under flowing deionized water for 20-30 s; then, put the obtained ceramic shell into a NaH2PO2 solution with a concentration of 18-30 g / L for reduction for 3-8 min; S3-5 Put the ceramic shell treated in step S3-4 into a plating solution and perform electroless plating at a temperature of 60-80 ℃; in the process of electroless plating, the plating solution is stirred at a constant speed, and the plating time is 20-40 min; S3-6 After the nickel plating is completed, the ceramic shell is taken out, washed, and heat treated at 180-250 ℃ for 40-60 min, and then cooled in the furnace to obtain the ceramic shell.

2. A ceramic / metal interface bonding method based on binder jetting molding, characterized by, The method comprises the following steps: S1 Based on 3D printing, design a pourable hollow ceramic shell according to the structure of a target casting; S2 Use a binder jetting molding technology to 3D print and manufacture the hollow ceramic shell to obtain a green body, and then sequentially perform solidification, vacuum infiltration, drying, and debinding sintering to obtain the ceramic shell; wherein the debinding sintering is used for sintering and removing the binder; S3 Use a vacuum dipping coating method to deposit a middle layer containing a metal material on the inner surface of the ceramic shell; S4 Use a casting method to fill a ferrous metal liquid into the ceramic shell in which the middle layer is deposited, perform temperature control solidification and heat preservation treatment, and then cool to obtain a casting with a ceramic / metal interface combination; In step S3, the coating is a mixture of aggregate and coating binder; wherein the coating binder is a silica sol with a solid content of 20-40 wt%; the aggregate is a metal element powder with a particle size of 1000-1200 mesh, and the metal element powder is nickel powder, chromium powder, or titanium powder; the mass percentage of the aggregate in the coating is 40-60 %; Step S3 specifically comprises the following sub-steps: S3.1 Stir the coating with a high-speed stirrer at a speed of 1500-2000 r / min for 10-15 min, and then perform vacuum dipping coating; the vacuum degree during vacuum dipping coating is 20-40 KPa, and the dipping time is 20-40 s; S3.2 Place the ceramic shell after vacuum dipping coating in a vacuum environment with a vacuum degree of 20-40 KPa for 1-2 h to completely precipitate bubbles in the coating; S3.3 Dry the ceramic shell treated in step S3.2 at a temperature of 40-60 ℃ for 18-24 h; S3.4 Perform sintering treatment on the ceramic shell treated in step S3.3 to sinter the coating; the process parameters of the sintering treatment are as follows: increase the temperature from room temperature to 1200-1300 ℃ at a heating rate of 2-4 ℃ / min, keep the temperature for 30-60 min, and finally cool to room temperature in the furnace.

3. The method of claim 1 or 2, wherein the binder jetting-based ceramic / metal interface bonding method is characterized by, The step S2 is specifically to pre-mix the ceramic powder to be printed with the sintering aid MnO2, and then to use the binder jet molding technology to 3D print the obtained mixture to obtain the green body; wherein the mass ratio of the sintering aid MnO2 in the mixture is 6%~10%, and the particle size of the sintering aid and the ceramic powder is between 500~2000 meshes; In step S2, the curing temperature used for curing is 160~220 ℃, and the curing time is 2~3 h; The infiltration liquid used in the vacuum infiltration is TiO2 sol, the solid content is 20~30 wt%, the infiltration time is 90~120 s, and the vacuum degree of infiltration is 20~30 KPa; The process parameters of the debinding and sintering are as follows: the temperature is increased from room temperature to 640~660 ℃ at a heating rate of 2~4 ℃ / min, and the temperature is kept for 60~90 min; then the temperature is increased to 950~1050 ℃ at a heating rate of 2~4 ℃ / min; then the temperature is increased to 1400~1450 ℃ at a heating rate of 1~2 ℃ / min, and the temperature is kept for 2~4 h; finally, the furnace is cooled to room temperature.

4. The method of claim 3, wherein the binder injection molding is performed by using a binder jetting apparatus. The ceramic powder is an alumina ceramic powder.

5. The method of bonding ceramic / metal interface according to claim 1 or 2, wherein the binder is injected in the form of a liquid. In step S4, the ferrous metal liquid is a 65Mn spring steel liquid; The casting is specifically gravity casting, and the pouring temperature used is 1600~1700 ℃; or the casting is specifically vacuum suction casting, and the pouring temperature used is 1550~1650 ℃, and the negative pressure used is -0.05 ~ -0.1 MPa.

6. The method of bonding ceramic / metal interface according to claim 1 or 2, wherein the binder is injected in the form of a liquid. In step S4, the ceramic shell is pre-heated at 1200 ℃ or above for 30~60 min before being poured; The temperature control solidification and heat preservation treatment is specifically to first cool the workpiece at a preset rate after pouring is completed, and to keep the temperature for 1~2 h every time the temperature is lowered by 100 ℃~200 ℃ in the range of 1600~1200 ℃, until the temperature is lowered to 700~800 ℃, and finally the furnace is cooled to room temperature; the preset rate is specifically 1~2 ℃ / min.

Images