CN119339991A - A metallization slurry and its preparation method and application - Google Patents

Abstract

The invention belongs to the technical field of metal slurry, and relates to a metalized slurry, a preparation method and application thereof. The metalized slurry comprises, by mass, 17.5% -18.1% of solvent, 0.9% -1.5% of ethylcellulose and 80.4% -81% of metal mixed powder, wherein the metal mixed powder comprises, by mass, 60% -70% of molybdenum powder, 10% -15% of manganese powder, 10% -15% of alumina powder, 5% -10% of silica powder, 1% -5% of magnesia powder and 0.2% -1% of polydimethylsiloxane modified fumed silica. The polydimethyl silane groups can form a three-dimensional winding network in the terpineol to form a thixotropic structure, and the surface of the part of the unmodified fumed silica forms hydrogen bonds with hydroxyl groups in the terpineol to generate thixotropic property. The problems that metal slurry flows unevenly in the screen printing process, a metallized layer cannot be conformal after printing, corners of the metallized layer are irregular, and peeling is caused are solved.

Description

Metallized slurry and preparation method and application thereof

Technical Field

The invention belongs to the technical field of metal slurry, and particularly relates to a metalized slurry, a preparation method and application thereof.

Background

The vacuum arc-extinguishing chamber is a core switching device in a medium-voltage circuit, and the vacuum degree is a key parameter of the device. The vacuum degree of the device is realized by sealing and welding a ceramic tube and a metal cover plate in a vacuum furnace, and the welding layer is a metallization layer, namely, the metal paste is printed on the ceramic end face by screen printing and sintered.

The quality of the metallization directly affects the level of sealing of the ceramic to the metal cover plate. In order to avoid virtual printing and leveling in the common process, the viscosity of the metal paste which is generally prepared is low, the metal paste flows unevenly in the screen printing process, and the metal paste needs to be immediately put into an oven to be dried for shape retention after the printing is finished. The method requires that the porcelain piece is stored flatly after silk screen printing is finished, the time interval for entering the oven is short, stricter operation requirements are put on production, and the metallized layer printed by the process shows overall trend difference of thicker edges and thinner middle parts.

Disclosure of Invention

The invention aims to provide a metalized paste, a preparation method and application thereof, and solves the problems that the metalized paste is unevenly scattered in the screen printing process, and a metalized layer shows overall trend difference with thicker edges and thinner middle parts.

The invention is realized by the following technical scheme:

The invention discloses a metalized slurry, which comprises 17.5-18.1% of solvent, 0.9-1.5% of ethylcellulose and 80.4-81% of metal mixed powder by mass percent;

The metal mixed powder comprises, by mass, 60% -70% of molybdenum powder, 10% -15% of manganese powder, 10% -15% of alumina powder, 5% -10% of silica powder, 1% -5% of magnesia powder and 0.2% -1% of polydimethylsiloxane modified fumed silica.

Further, terpineol is used as the solvent.

Further, the preparation process of the polydimethylsiloxane modified fumed silica comprises the following steps:

Mixing dimethyl siloxane and fumed silica at 150-250 ℃, and grinding for 5-10 hours to prepare the dimethyl siloxane fumed silica.

The invention also discloses a preparation method of the metalized slurry, which comprises the following steps:

1) Preparing metal mixed powder;

mixing solvent terpineol and ethyl cellulose, heating and stirring to fully dissolve the ethyl cellulose;

2) Mixing the dissolved ethyl cellulose with metal mixed powder, ball milling and sieving to obtain the metalized slurry.

5. In the step 1), the parameters of heating and stirring are that heating is carried out at 110-140 ℃, and the stirring rotating speed is 1-2r/min.

Further, in the step 2), the ball milling is specifically carried out in a ball milling tank for 18-24 hours.

The invention also discloses application of the metalized slurry in preparing a vacuum arc-extinguishing chamber, wherein the metalized slurry forms a metalized layer which is used as a transition layer for connecting metal and ceramic.

Further, the qualified metalized slurry is silk-screened on the end face of the alumina ceramic tube, and sintered at 1400-1500 ℃ to obtain a metalized ceramic tube fitting;

Wherein, during sintering, sintering is carried out in a sintering atmosphere of hydrogen and nitrogen atmosphere;

After the metallized ceramic pipe fitting is electroplated, the metallized ceramic pipe fitting is placed in a vacuum furnace, silver-copper solder is placed between the metal cover plate and the metallized layer, then vacuumizing is carried out, welding is carried out after heating, and the metal cover plate and the ceramic piece are connected with each other.

Compared with the prior art, the invention has the following beneficial technical effects:

The invention discloses a metallization slurry, which adopts polydimethylsiloxane modified fumed silica to replace part of silicon oxide in a glass component in a traditional metallization slurry formula in metal mixed powder, and uses part of polydimethylsiloxane modified fumed silica to replace crystalline silicon oxide, so as to form a new formula system, improve the thixotropic property of the metal slurry, and further realize the improvement of the quality of a metallization layer. The modified gas-phase silicon oxide can be smoothly dissolved in terpineol, the polydimethyl silane group can form a three-dimensional winding network in the terpineol to form a thixotropic structure, and meanwhile, the surface of part of the unmodified gas-phase silicon oxide forms a hydrogen bond with hydroxyl in the terpineol to generate thixotropic. The modified gas phase silicon oxide of the polydimethylsiloxane can increase the thixotropic property of the metalized paste, solves the problems that the metalized paste flows unevenly in the screen printing process, a metalized layer cannot be conformal after printing, corners of the metalized layer are irregular and skinning, and the tensile strength of the metalized layer is slightly increased after the modified gas phase silicon oxide is added, so that the product performance is not affected. In a word, the invention replaces the glass powder component in the original metal paste formulation with the crystal powder for forming glass, and uses partial modified gas phase silicon oxide to replace the crystal silicon oxide, so that the metalized paste shows stronger thixotropic property, thereby reducing the requirements on storage and drying of silk-screen products, simultaneously reducing the thickness difference of metalized layers, and omitting the process of preparing glass powder by the crystal powder.

The polydimethyl silane groups can form a three-dimensional winding network in terpineol, so that the viscosity of the metalized slurry is reduced when the shearing force is increased, and the viscosity of the metalized slurry is increased when the shearing force is disappeared. The special performance is well adapted to the requirements of screen printing, namely, when the sizing agent is printed, the viscosity of the sizing agent is reduced immediately due to the action of shearing force and the sizing agent spreads on the surface of a printed porcelain, but after the shearing force is removed, the viscosity of the sizing agent is increased immediately, the shape of printing is ensured, and the scattering of the sizing agent is reduced, so that the sizing agent is uneven.

Furthermore, the process of preparing the crystal grain powder into a glass body, then water quenching and grinding is omitted by replacing the glass powder in the original formula with the polydimethylsiloxane modified gas phase silicon oxide.

The invention also discloses an application of the metallized slurry in preparing a vacuum arc-extinguishing chamber, and the production of the metallized ceramic part of the vacuum arc-extinguishing chamber is to screen print the metal paste on the sintered ceramic, so that certain shrinkage can be generated in the sintering process of the metal paste. The shrinkage of the sintering is constant, but the actual shrinkage value depends on the end face width of the silk-screened ceramic. For the porcelain piece with larger end face width, the shrinkage rate is unchanged, but the actual shrinkage value is increased, and the porcelain piece is sintered and cannot shrink any more, so that the metalized layer of the porcelain piece with wider end face is easy to peel after being sintered.

Because the inorganic polydimethylsilane modified gas silicon is added, partial organic additives (the content of ethyl cellulose, terpineol, hydrogenated castor oil and the like is reduced) in the metal slurry can be replaced, and the shrinkage of the ceramic metallization layer in the sintering process is reduced, so that the peeling phenomenon of the wide-surface metallization layer caused by overlarge shrinkage value is reduced.

Drawings

FIG. 1 is a graph of the rheological properties of a metallized slurry prepared in accordance with the present invention;

FIG. 2 is a graph showing sag resistance of the metal paste prepared in the present invention after printing, which is vertically placed for 0 hours, wherein a is a graph showing sag resistance of the metal paste prepared in the comparative example, and b is a graph showing sag resistance of the metal paste prepared in the example 4;

Fig. 3 is a graph showing sag resistance of the metallization paste prepared in the invention after printing, which is vertically placed for 1 hour, wherein a graph a shows a graph showing sag resistance of the metallization paste prepared in the comparative example, and b graph b shows a graph showing sag resistance of the metallization paste prepared in the example 4.

Detailed Description

The objects, technical solutions and advantages of the present invention will be more apparent from the following detailed description with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the invention, i.e., the embodiments described are merely some, but not all, of the embodiments of the invention.

The components illustrated in the figures and described and shown in the embodiments of the invention may be arranged and designed in a wide variety of different configurations, and thus the detailed description of the embodiments of the invention provided in the figures below is not intended to limit the scope of the invention as claimed, but is merely representative of selected ones of the embodiments of the invention. All other embodiments, which can be made by a person skilled in the art without making any inventive effort, are intended to be within the scope of the present invention, based on the figures and embodiments of the present invention.

It should be noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, element, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, element, method, article, or apparatus.

The invention discloses a metalized slurry, which comprises 17.5-18.1% of solvent, 0.9-1.5% of ethylcellulose and 80.4-81% of metal mixed powder by mass percent;

The metal mixed powder comprises, by mass, 60% -70% of molybdenum powder, 10% -15% of manganese powder, 10% -15% of alumina powder, 5% -10% of silica powder, 1% -5% of magnesia powder and 0.2% -1% of polydimethylsiloxane modified fumed silica.

The preparation process of the polydimethylsiloxane modified fumed silica comprises the following steps:

Mixing dimethyl siloxane and fumed silica at 150-250 ℃, and grinding for 5-10 hours to prepare the dimethyl siloxane fumed silica.

The corresponding performance verification of the metalized slurry is carried out in the following aspects:

a) The rheological properties of the slurries were tested using a viscometer.

B) The slurry was screen printed onto 95 alumina tiles and then placed vertically for 1 hour and the sag resistance of the metallized slurry was observed in comparison.

C) Sintering the silk-screened ceramic chip in a sintering furnace in the atmosphere of hydrogen and nitrogen at 1400-1500 ℃ to obtain a metallized ceramic piece;

After the metallized porcelain piece is electroplated, silver-copper solder is used for connection, and a three-point bending-resistant method is adopted for testing the sealing strength of the metallized layer.

The metalized slurries prepared in the following examples were all verified by the verification method described above, and will not be described in detail.

The features and properties of the present invention are described in further detail below with reference to examples.

Example 1

The embodiment discloses a preparation method of a metalized slurry, which comprises the following steps:

1) 17.5g of terpineol and 1g of ethyl cellulose are added into a stirring tank, and the mixture is heated and stirred to fully dissolve the ethyl cellulose.

2) The dissolved ethylcellulose was transferred into a ball mill pot, 81.5g of metal mixed powder was added, and ground in the ball mill pot for 18 hours, and passed through a 300 mesh screen to obtain a metallized slurry, which was designated as sample 1.

Wherein, the metal mixed powder comprises 60 percent of molybdenum powder, 15 percent of manganese powder, 15 percent of alumina powder, 4.6 percent of silica powder, 5 percent of magnesia powder and 0.4 percent of polydimethylsiloxane modified fumed silica by mass percent.

Example 2

The embodiment discloses a preparation method of a metalized slurry, which comprises the following steps:

1) 18g of terpineol and 1.5g of ethyl cellulose are added into a stirring tank, and the mixture is heated and stirred to fully dissolve the ethyl cellulose.

2) The dissolved ethylcellulose was transferred into a ball mill pot, 80.5g of metal mixed powder was added, and ground in the ball mill pot for 24 hours, and passed through a 300 mesh screen to obtain a metallized slurry, which was designated as sample 2.

Wherein, the metal mixed powder comprises 65 percent of molybdenum powder, 13 percent of manganese powder, 10 percent of alumina powder, 9.4 percent of silica powder, 2 percent of magnesia powder and 0.5 percent of polydimethylsiloxane modified fumed silica by mass percent.

Example 3

The embodiment discloses a preparation method of a metalized slurry, which comprises the following steps:

1) 18.1g of terpineol and 1.5g of ethylcellulose were added to the stirring tank, and the mixture was heated and stirred to sufficiently dissolve the ethylcellulose.

2) The dissolved ethylcellulose was transferred into a ball mill pot, 80.4g of metal mixed powder was added, and ground in the ball mill pot for 24 hours, and passed through a 300 mesh screen to obtain a metallized slurry, which was designated as sample 3.

Wherein, the metal mixed powder comprises 70 percent of molybdenum powder, 10 percent of manganese powder, 11.2 percent of alumina powder, 5 percent of silica powder, 3 percent of magnesia powder and 0.8 percent of polydimethylsiloxane modified fumed silica by mass percent.

Example 4

The embodiment discloses a preparation method of a metalized slurry, which comprises the following steps:

1) 18g of terpineol and 0.9g of ethyl cellulose are added into a stirring tank, and the mixture is heated and stirred to fully dissolve the ethyl cellulose.

2) The dissolved ethylcellulose was transferred into a ball mill pot, 81.1g of metal mixed powder was added, and ground in the ball mill pot for 24 hours, and passed through a 300 mesh screen to obtain a metallized slurry, which was designated as sample 4.

Wherein, the metal mixed powder comprises 63% of molybdenum powder, 12% of manganese powder, 13% of alumina powder, 10% of silica powder, 1% of magnesia powder and 1% of polydimethylsiloxane modified fumed silica by mass percent.

When the method is applied, the qualified metalized slurry is silk-screened on the end face of an alumina ceramic tube, and sintered at 1400-1500 ℃ to obtain a metalized ceramic tube;

Wherein, during sintering, sintering is carried out in a sintering atmosphere of hydrogen and nitrogen atmosphere;

After the metallized ceramic pipe fitting is electroplated, the metallized ceramic pipe fitting is placed in a vacuum furnace, silver-copper solder is placed between a metal cover plate and a metallized layer, then the vacuum is pumped to 10 ^-5 Pa, the temperature is raised to 850 ℃, and the metal cover plate can be connected with the ceramic piece. Because the sealing is carried out in the vacuum furnace, the vacuum degree in the ceramic tube is the same as that of the vacuum furnace, and the condition of the vacuum degree required by the vacuum arc extinguishing chamber can be realized.

Glass powder is adopted as the glass component in the original metal slurry formula, and glass-forming crystal powder is adopted in the improved formula, so that the process of dissolving powder into glass and then water quenching and grinding can be reduced.

Comparative example 1

Unlike example 4, the formulation of the metal mixed powder was different and the final product was designated sample 5.

The metal mixed powder comprises 63% of molybdenum powder, 12% of manganese powder, 13% of alumina powder, 11% of silica powder and 1% of magnesia powder by mass percent.

Comparative example 2

Unlike example 4, the formulation of the metal mixed powder was different and the final product was designated sample 6.

The metal mixed powder comprises 63% of molybdenum powder, 12% of manganese powder, 13% of alumina powder, 11% of silica powder, 1% of magnesia powder and 1% of fumed silica by mass percent.

Comparative example 3

Unlike example 4, the formulation of the metal mixed powder was different and the final product was designated sample 7.

The metal mixed powder comprises 63% of molybdenum powder, 12% of manganese powder, 13% of alumina powder, 11% of silica powder, 1% of magnesia powder and 1.5% of polydimethylsiloxane modified fumed silica in percentage by mass.

Performance verification was performed for the 4 examples above and the comparative examples, specifically introduced in terms of four aspects of rheological properties, sag resistance properties, metallization layer thickness differences, and metallization layer strength.

1. Rheological characteristics

The results shown in FIG. 1 were obtained, and it can be seen from FIG. 1 that the addition of 0% fumed silica metalizing slurry maintained a shear rate of substantially 20000cps from 10-100RPM viscosity.

The viscosity of the metal paste increases from 20000cps to around 70000cps as the amount of fumed silica added increases at a shear rate of 10RPM, but increases from 20000cps to 26000cps at a high shear rate of 100RPM, with the viscosity remaining substantially unchanged.

The metalized slurry prepared by the embodiment of the invention has high viscosity when no shearing force or low shearing force exists, and the viscosity of the slurry is reduced when the shearing force is higher. The special performance is well adapted to the requirements of screen printing, namely, when the sizing agent is printed, the viscosity of the sizing agent is reduced immediately due to the action of shearing force and the sizing agent spreads on the surface of a printed porcelain, but after the shearing force is removed, the viscosity of the sizing agent is increased immediately, the shape of printing is ensured, and the scattering of the sizing agent is reduced, so that the sizing agent is uneven.

2. Sag resistance characteristics

The graph a in fig. 2 shows a sample to which fumed silica was not added, i.e., sample 5 prepared in the comparative example, and the graph b in fig. 2 shows a sample to which fumed silica of 1% was added. It can be seen from fig. 2 that the edges form an arc shape due to the liquid surface tension after the printing of the metallizing paste without added silica is completed (standing vertically for 0 hours).

After standing vertically for 1 hour, as shown in a graph a in fig. 3, the slurry without fumed silica was clearly flowed down to form an arc liquid-solid boundary. And a sample added with 1% of gas phase silicon oxide, as shown in a b diagram in fig. 2 and a b diagram in fig. 3, the boundary between the metal paste and the metal paste is clear in 0 hour and 1 hour when the sample is vertically placed, no paste flow signs exist, and the boundary precision and uniformity of screen printing are well maintained.

3. Thickness deviation of post-screen metallization layer

And measuring the two ends and the middle part of the metallization layer by adopting an X-ray fluorescence thickness gauge. A comparison test was carried out using a porcelain piece having an end face width of 5.5mm of the experimental porcelain piece.

From the table above, it can be seen that the thickness difference between the middle and the two edges of the metallization layer can be obviously reduced in the silk-screen printing process after 1% of modified gas silicon is added. This is because, in the screen printing process, the adhesion of the metallizing paste to the screen is caused when the screen is lifted after the printing is completed. After the air inlet silicon is added, the viscosity of the sizing agent is increased sharply after the screen is stopped printing, the screen can be disconnected from the sizing agent in a short time, and the increase of the thickness of the edge caused by the accumulation of the sizing agent at the edge is maintained.

After 1.5% of modified gas silicon is added, the viscosity of the slurry is increased in the silk screen printing process, the metallization layer printed on the porcelain piece is intermittent, the metallization layer shows obvious silk screen printing reticulate patterns, and the paste cannot be leveled.

After the unmodified fumed silica was added in comparative example 2, the fumed silica was not dissolved in the mixed solvent of terpineol, and the fumed silica floated on the surface of the solvent. The prepared paste does not show obvious thixotropic improving effect when being screen printed.

4. Strength of metallization layer

The strength test was performed on the metallized pastes prepared in the above 4 examples and the samples prepared in the comparative examples, and the results are shown in table 1.

TABLE 1

In conclusion, the gas-phase silicon oxide can well change the performance of the metalized slurry, solve the problems of uneven flow of the metal slurry, poor shape retention and the like in the screen printing process, and the tensile strength of the metalized layer is slightly increased after the gas-phase silicon oxide is added, so that the product performance is not affected.

After the silicon oxide in the formula is replaced by the modified fumed silica, the replaced part of fumed silica plays 2 roles, and the first is to improve the rheological property of the slurry before sintering the metalized slurry, namely, the slurry generates thixotropic property, and the slurry has dispersibility on metal powder. The second effect is the sintering aid-generating effect in the formulation, which is the same as the original silica effect.

Finally, it should be noted that the above embodiments are only for illustrating the technical solution of the present invention and not for limiting the same, and although the present invention has been described in detail with reference to the above embodiments, it should be understood by those skilled in the art that modifications and equivalents may be made to the specific embodiments of the present invention without departing from the spirit and scope of the present invention, and any modifications and equivalents are intended to be included in the scope of the claims of the present invention.

Claims (8)

1. A metallization slurry, characterized in that, in terms of mass percentage, it comprises 17.5%-18.1% solvent, 0.9%-1.5% ethyl cellulose and 80.4%-81% metal mixed powder; In terms of mass percentage, the metal mixed powder includes 60%-70% molybdenum powder, 10%-15% manganese powder, 10%-15% aluminum oxide powder, 5%-10% silicon oxide powder, 1%-5% magnesium oxide powder, and 0.2%-1% polydimethylsiloxane-modified fumed silica. 2. The metallization slurry according to claim 1, characterized in that the solvent is pineol. 3. The metallization slurry according to claim 1, characterized in that the preparation process of the polydimethylsiloxane-modified fumed silica is: Under the condition of 150-250° C., dimethylsiloxane and fumed silica are mixed and ground for 5-10 hours to prepare polydimethylsiloxane fumed silica. 4. The method for preparing the metallization paste according to any one of claims 1 to 3, characterized in that it comprises the following steps: 1) Preparing metal mixed powder; Mix the solvent terpineol and ethyl cellulose, heat and stir to fully dissolve the ethyl cellulose; 2) Mixing the dissolved ethyl cellulose with the metal mixed powder, ball milling and sieving to obtain a metallized slurry. 5. The method for preparing a metallization slurry according to claim 4, characterized in that in step 1), the parameters of heating and stirring are: heating at 110-140°C and stirring at a speed of 1-2 r/min. 6. The method for preparing a metallization slurry according to claim 4, characterized in that in step 2), the ball milling specifically comprises: grinding in a ball mill for 18-24 hours. 7. Use of the metallization slurry according to any one of claims 1 to 3 in the preparation of a vacuum arc chamber, characterized in that the metallization slurry forms a metallization layer, and the metallization layer serves as a transition layer connecting metal and ceramic. 8. The use of the metallization slurry in the preparation of a vacuum interrupter according to claim 7, characterized in that the metallization slurry prepared to the standard is screen-printed on the end face of an alumina ceramic tube, and sintered at 1400-1500° C. to obtain a metallized ceramic tube; Wherein, during sintering, sintering is carried out in a sintering atmosphere of hydrogen and nitrogen atmosphere; After electroplating the metallized ceramic pipe fittings, the metallized ceramic pipe fittings are placed in a vacuum furnace, silver-copper solder is placed between the metal cover plate and the metallized layer, and then vacuumed and heated for welding, so that the metal cover plate and the ceramic parts are connected to each other.