KR101011606B1 - Method for Metallizing on Ceramic - Google Patents

Abstract

The present invention relates to a metallizing method of ceramics, comprising: preparing a paste uniformly mixed with an organic binder by mixing 90 to 70 wt% molybdenum and 10 to 30 wt% metal manganese; Applying the paste to the surface (2) of the alumina sintered body (1); And changing the amount of hydrogen gas to nitrogen gas passed through the alumina sintered body coated as described above through a humidifier filled with water at 10 to 20 ° C., that is, the ratio of the partial pressure of hydrogen to the partial pressure of water log (PH ₂ O / PH ₂ ) by changing the range from -1.64 to -1.34 to metallization at a temperature range of 1450 ~ 1550 ℃, the metallization method of the ceramic according to the present invention is to prevent the oxidation of molybdenum and manganese It promotes oxidation and promotes wetting of molybdenum, manganese oxide and glass phase, thereby improving the bonding strength of ceramic-metal or ceramic-ceramic.

Ceramic, Metallizing, Metal Molybdenum, Metal Manganese, Adhesive Strength

Description

Metalizing method of ceramics {Method for Metallizing on Ceramic}

1 is a graph showing the equilibrium relationship between metal and metal oxides in a hydrogen atmosphere.

2 is a cross-sectional view showing the alumina specimen used in the present invention.

3 is a cross-sectional view showing a KOVAR washer used in the present invention.

4 is an assembly view showing a brazing specimen used in the present invention.

The present invention relates to a metallizing method for coating a metal layer on the surface of a ceramic. More specifically, the present invention provides excellent adhesion strength by controlling the partial pressure of water, ie, PH ₂ O / PH ₂ , to hydrogen that causes metal molybdenum not to oxidize and metal manganese to oxidize during the metallizing process of ceramics. A method of metallizing ceramics to have.

H. Vatter first metallizes metal powders such as iron (Fe), chromium (Cr), nickel (Ni) and tungsten (W) in steatite ceramics under vacuum (German Patent No. 645,871 (1935) April). After that, General Electric Co.'s HJ Nolte and RF Spurck (Television Engineering, 1 [11], 14-16, 18, 19 (1950)) are sensitive to dew point and process control. Considering its low reliability and low reliability, the Mo-Mn process using manganese (Mn) was developed in a humidified hydrogen atmosphere instead of iron. The Mo-Mn method prevents the oxidation of molybdenum (Mo) forming the metal layer while maintaining a thermodynamic atmosphere in which only manganese is oxidized and diffuses into the glass phase on the surface of the alumina ceramic. Consideration should be given to equilibrium relationships. Thus, WH Chang induced the equilibrium relationship of dew point with respect to the temperature of molybdenum and manganese, which is shown in FIG. According to FIG. 1, molybdenum is stable using the condition where the ratio of temperature-dew point is to the right of the bottom of the curve, and if this value is above the left of the curve, the molybdenum is oxidized. As such, it is difficult to predict the oxidation and reduction of molybdenum, and in particular, a significant amount of molybdenum oxides MoO ₂ and MoO ₃ are volatilized at the metallizing temperature. That is, the dew point is not only important as a thermodynamic equilibrium relationship that facilitates bonding by oxidizing only manganese to manganese oxide (MnO) while preventing the oxidation of molybdenum, but also has much wettability and bonding strength between molybdenum and glass phase. Will be affected.

However, the conventional method of performing metallizing of such ceramics is performed without precise control of dew point, that is, partial pressure of water to hydrogen, that is, PH ₂ O / PH ₂ , thereby lowering the bonding strength of ceramic-metal or ceramic-ceramic. There is a problem.

If the partial pressure of water to hydrogen, ie PH ₂ O / PH ₂ , is not controlled correctly during the metallization process of ceramics, it will not promote the prevention of molybdenum oxidation and the oxidation of manganese, or reduce the wettability of molybdenum and manganese oxide. There is a problem of lowering the bonding strength of metal or ceramic-ceramic.

In order to solve the above problems, the present invention to solve the various problems by performing without precise control of the dew point of the atmosphere gas, that is, the partial pressure of water to hydrogen PH ₂ O / PH ₂ during the metallizing process of the conventional ceramic Invented by controlling the relative amount of nitrogen and hydrogen gas used to control the atmosphere of metallization, ie the temperature of the humidifier and the amount of nitrogen gas passing through to control the partial pressure of water to hydrogen An object of the present invention is to provide a metallization method of ceramics that promotes oxidation of molybdenum and manganese, and promotes wetting of molybdenum, manganese oxide and glass phase to improve the bonding strength of ceramic-metal or ceramic-ceramic.

The above and other objects of the present invention can be achieved by the present invention described below.

In order to achieve the above object, the present invention comprises the steps of preparing a paste homogeneously mixed with an organic binder by mixing molybdenum 90 to 70% by weight and metal manganese 10 to 30% by weight; Applying the paste to the surface (2) of the alumina sintered body (1); And changing the amount of hydrogen gas to nitrogen gas passed through the alumina sintered body coated as described above through a humidifier filled with water at 10 to 20 ° C., that is, the ratio of the partial pressure of hydrogen to the partial pressure of water log (PH _It provides a metallizing method of the ceramic comprising a; ₂ / O / PH ₂ ) in the range of -1.64 to -1.34 to metallize at a temperature range of 1450 ~ 1550 ℃.

Hereinafter, the present invention will be described in detail.

Metallizing method of the ceramic according to the present invention is a paste prepared by mixing 90 to 70% by weight of molybdenum and 10 to 30% by weight of metal manganese with an organic binder (Type 424 vehicla, Elecro-Science Lab., INC., USA) Is applied to the surface 2 of the alumina sintered body 1, and then hydrogen gas to nitrogen gas passed through a humidifier filled with water at 10 to 20 ° C. in order to not oxidize molybdenum but to manganese. While varying the amount, that is, the ratio of the partial pressure of hydrogen to the partial pressure of water, that is, log (PH ₂ O / PH ₂ ) is characterized in that the metallization to 1450 ~ 1550 ℃ by changing in the range of -1.64 to -1.34.

The bonding mechanism of the Mo-Mn method is a glass phase in which a high melting point metal such as molybdenum or tungsten is sintered to form a skeleton of a high melting point metal, and a glass phase formed of an additive in alumina fills pores of the high melting point metal to form a metallization layer. A moving mechanism and a reactor mechanism by a reaction in which a manganese-aluminum spinel and a magnesium-aluminum spinel layer are formed at the interface between the metallizing layer and the alumina sintered body have been proposed.                     

Adding 10% by weight or less of manganese to molybdenum does not form a sufficient glass phase that can migrate to the alumina sintered body and thus does not form a solid metallization layer. When the content of manganese in molybdenum is added to 30% by weight or more, manganese oxide is excessively produced, and spinel is formed by the interdiffusion of elements such as silicon (Si), aluminum (Al), and calcium (Ca) in manganese oxide and alumina. The excessive generation of the layer causes a problem of lowering the strength characteristics of the alumina base material due to the difference in thermal expansion between the spinel and the alumina, which is not suitable as a metallizing composition of the alumina sintered body.

During the metallizing process of alumina ceramics, the amount of hydrogen gas to nitrogen gas passed through a humidifier filled with water at 20 ° C in order to ensure that the molybdenum does not oxidize and the manganese is oxidized. If the ratio of hydrogen partial pressure, that is, log (PH ₂ O / PH ₂ ) is lower than -1.64 or higher than -1.34, it prevents the oxidation of molybdenum and the oxidation of manganese, and prevents the wetting of molybdenum, manganese oxide and glass phase. It lowers the bonding strength of the ceramic-metal or ceramic-ceramic.

After adjusting the ratio of the partial pressure of hydrogen to the partial pressure of water, that is, log (PH ₂ O / PH ₂ ) within the range of -1.64 to -1.34, and the metallizing temperature of the ceramic is lower than 1450 ° C, the glass phase of manganese oxide and alumina The temperature is low to react with the spinel and the movement speed of the manganese oxide is so slow that it cannot be sufficiently transferred to the alumina, so that the bonding strength of the metallized alumina sintered body is very low, making it unsuitable for use as a product. And heat treatment at a high temperature of 1550 ℃ or higher is higher than the sintering temperature of the alumina sintered body is not suitable for the metallizing temperature.

Hereinafter, the present invention will be described in more detail with reference to the following examples, but the scope of the present invention is not limited to the examples.

[Examples 1 to 3] and [Comparative Examples 1 to 4]

3 on the surface 2 of the alumina specimen (1, the same specifications as the American ASTM ASTM F19-64 specimen) having a purity of 96% having an inner diameter of 10.4 mm, an outer diameter of 29.4 mm, and a height of 14.5 mm, as shown in FIG. The present invention was implemented by joining a KOVAR washer 3 having an outer diameter of 16.3 mm and a head thickness of 0.6 mm.

A paste of 80 mol% of molybdenum powder and 20 wt% of manganese was applied to a surface 2 of the alumina sintered body 1 using a 90 micron thick, 325 mesh stainless steel sieve, and dried. In order to change the ratio of the partial pressure of hydrogen, that is, log (PH ₂ O / PH ₂ ), the amount of nitrogen gas and hydrogen gas that passed through a dew point of 20 ° C. was 0.5 and 2.5, 0.75 and 2.25, 1 and 2, 1.5 and Metallization of alumina was carried out by maintaining the temperature at 1500 ° C. for 30 minutes in a mixed gas atmosphere of 1.5, 1.76 and 1.24, 2 and 1, and 2.3 and 0.7 liters / minute. The metallized specimens were washed with acetone and caustic soda solution and nickel plated by the nickel electroless plating method. As shown in FIG. 4, the metallized and nickel plated alumina sintered body 4 was coated with a cobar washer using a filler metal 5 having a composition of 72% by weight of silver (Ag) having a thickness of 50 microns-28% by weight of copper (Cu). (3) was sandwiched and fixed with graphite jig (6), and then brazed at 800 ° C. for 20 minutes to raise the temperature and cooling rate to 20 ° C./min.

The bond strength of the brazed alumina specimen was calculated by dividing the maximum load when the specimen is broken by the joint area using a tensile strength jig, which is tensioned at a crosshead speed of 0.5 mm / min using a universal testing machine. The results are shown in Table 1.

Metallizing conditions log (PH ₂ O / PH ₂ )
ceramic-
Bonding strength of metal
When measuring
Plane of destruction Bonding strength
(MPa) Wet Nitrogen
(Liters / minute) Hydrogen
(Liters / minute) Comparative example One 0.5 2.5 -2.34 molybdenum/
Alumina interface 2.6 2 0.75 2.25 -2.12 " 6.9 3 1.0 2.0 -1.94 " 8.4 4 2.5 0.5 -0.93 " 26.3 Example One 1.5 1.5 -1.64 Alumina surface 32.7 2 1.76 1.24 -1.48 " 42.9 3 2.3 0.7 -1.12 " 33.9

As shown in Table 1, when the ratio of hydrogen partial pressure to water partial pressure, that is, log (PH ₂ O / PH ₂ ) is less than -1.64 or greater than -1.12, the prevention of the oxidation of molybdenum and the oxidation of manganese is suppressed, or molybdenum Due to poor wettability with manganese oxide and glass phase, ceramic-metal bond strength was low and not suitable.

[Examples 4 to 6] and [Comparative Examples 5 to 8]                     

72% by weight of silver (Ag) having a thickness of 50 microns between the metallized and nickel plated alumina sintered body 4 to perform metallization in the same manner as in Example 1 and to measure the bonding strength of the ceramic-ceramic The filler metal 5 having a composition of 28% by weight of copper (Cu) was fixed with the graphite jig 6 and then brazed at 800 ° C. for 20 minutes with a temperature raising and cooling rate of 20 ° C./min. Bonding strength was measured in the same manner as in Example 1, and the results are shown in Table 2.

Metallizing conditions log (PH ₂ O / PH ₂ ) ceramic-
Ceramic bonding strength
When measuring
Plane of destruction Bonding strength
(MPa) Wet Nitrogen
(Liters / minute) Hydrogen
(Liters / minute) Comparative example 5 0.5 2.5 -2.34 molybdenum/
Alumina interface 1.1 6 0.75 2.25 -2.12 " 1.2 7 1.0 2.0 -1.94 " 3.7 8 2.5 0.5 -0.93 7.1 Example 4 1.5 1.5 -1.64 Alumina surface 23.5 5 1.76 1.24 -1.48 " 29.5 6 2.3 0.7 -1.12 " 16.7

Similar to the ceramic-metal bond strength, the ratio of hydrogen partial pressure to partial pressure of water, ie, log (PH ₂ O / PH ₂ ) is less than -1.64 or greater than -1.12, prevents the oxidation of molybdenum and the oxidation of manganese. It was suppressed or the wettability of molybdenum, manganese oxide and glass phase was poor, so that the bonding strength value of ceramic-metal was not suitable.

EXAMPLES 7-12                     

The ratio of the partial pressure of hydrogen to the partial pressure of water showing the optimum strength in Examples 1 to 6, that is, the amount of manganese added to molybdenum under metallization conditions in which log (PH ₂ O / PH ₂ ) is -1.48 is 10, 15, 20, 25 and 25% by weight of paste were prepared and metallized, nickel plated and brazed in the same manner as in Example 1. Bonding strength of the ceramic-metal was measured as in Example 1, and the results are shown in Table 3.

Furtherance Metalizing
Temperature and time Bonding strength
Destructive surface at the time of measurement Bonding strength
(MPa) molybdenum manganese Example 7 90 10 1500 ° C., 30 minutes Alumina surface 48.7 8 90 10 1550 ℃, 30 minutes " 53.1 9 85 15 1450 ° C, 30 minutes " 48.5 10 80 20 1450 ° C, 30 minutes " 31.9 11 75 25 1550 ℃, 30 minutes " 39.9 12 70 30 1450 ° C, 30 minutes " 35.8

As can be seen from Table 3, the ratio of the partial pressure of hydrogen to the partial pressure of water for optimum strength, i.e. log (PH ₂ O / PH ₂ ) is added from 10 to 30% by weight of manganese to 70 to 90% by weight of molybdenum at -1.48. Very good bonding strength was obtained by controlling the paste and metallizing temperature to 1450 ~ 1550 ℃.

As described above, the metallizing method of the ceramic according to the present invention provides a partial pressure of water to hydrogen during the metallizing process, that is, a temperature of a humidifier and nitrogen passing through for accurate control of PH ₂ O / PH ₂ . By adjusting the amount of gas and the amount of hydrogen gas, it promotes the prevention of molybdenum oxidation and manganese oxidation, and promotes the wetting of molybdenum, manganese oxide and glass phase to improve the bonding strength of ceramic-metal or ceramic-ceramic. It is a useful invention that works.

While the invention has been described in detail above with reference to the described embodiments, it will be apparent to those skilled in the art that various modifications and variations are possible within the scope and spirit of the invention, and such modifications and variations fall within the scope of the appended claims. It is also natural.

Claims (1)

Preparing a paste homogeneously mixed with an organic binder by mixing 90 to 70 wt% molybdenum and 10 to 30 wt% metal manganese; Applying the paste to the surface (2) of the alumina sintered body (1); And The ratio of the hydrogen partial pressure to the partial pressure of water is changed while changing the amount of hydrogen gas with respect to the nitrogen gas passed through the humidifier filled with water of 10 to 20 ° C. in the alumina sintered body coated as described above (PH ₂ O / PH ₂ ) in the range of -1.64 to -1.34 to metallize at a temperature range of 1450-1550 ° C .; Metallizing method of the ceramic, characterized in that comprises a.

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