JPH06172053A - Production of ceramic-metal bonded material - Google Patents

Abstract

PURPOSE:To prevent galling in insertion and to provide a ceramic-metal bonded material exhibiting a low residual stress after insertion and bonding under pressure and capable of maintaining a strong bonding force. CONSTITUTION:In production of a ceramic-metal bonded material by applying a lubricant to the bonding surface 5 between a ceramic member 2 and a metal member 3 and inserting the ceramic member into a depression part or a through hole of the metal member under pressure and bonding to each other, the above- mentioned lubricant is composed mainly of a carboxylic acid, a carboxylic acid salt, a carboxylic acid derivative or a substituted carboxylic acid and the above-mentioned insertion between both the members is subsequently carried out under a condition where the surface pressure Pm generated between the bonding surfaces and the insertion length L satisfy formula 10<=Pm<=100 [kgf/ mm<2>] and formula 30<=Pm<=L [kgf/mm]. A heat treatment is subsequently applied thereto until the coefficient of friction of the lubricant-applied parts when being pulled out becomes higher than the coefficient of friction at a point of time of insertion.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a combined body of ceramics and metal. The present invention can be suitably used particularly for turbine rotors, rocker arms, tappets, boring bars and the like.

[0002]

2. Description of the Related Art Conventionally, in a combination of ceramic and metal, which is used for a turbocharger rotor, a turbine rotor, etc., a concave portion (or a through hole) is provided in a metal member and the concave portion is formed. There is known a structure in which a ceramic member is press-fitted in and the two members are joined by the pressing force of each member.

This "press-fitting" is a useful joining method in which it is not necessary to interpose a joining material such as a brazing filler metal in the middle, and thermal shock is not applied during joining, but one member of the joining body is made of ceramics. If an attempt is made to increase the pressing force at a certain time, a phenomenon called galling occurs between the ceramics 3 and the metal 1, that is, the metal adheres to the ceramics during press fitting and the inner surface of the concave portion of the metal becomes slumped. However, there is a drawback that the press-fitting load is extremely increased. Therefore, there have been problems that residual stress is generated in the joint portion, the joint strength is lowered, or the center of gravity of the manufactured component is unbalanced.

Therefore, in order to suppress the above-mentioned galling, there has been conventionally proposed a technique in which a lubricant or lubricating oil such as molybdenum disulfide, graphite and higher alcohol containing animal fat is applied to the joint portion in advance and press-fitted. (JP-A-4-134715, etc.).

[0005]

[Problems to be Solved by the Invention]
As in the technique described in Japanese Patent No. 34715, with a lubricating oil such as a higher alcohol containing animal fat, it is not possible to sufficiently reduce the friction coefficient between both members at the time of press fitting.
Under a high surface pressure such as a surface pressure Pm> 20 kgf / mm ² and a product Pm · L> 80 kgf / mm of the surface pressure and the press-fit length L, galling could still not be prevented.

Further, Pm <15 kgf / mm ² , Pm ·
Under a low surface pressure such as L <60 kgf / mm, the residual stress of the joint surface is relatively high in spite of the low surface pressure. Therefore, the joint portion with the metal shaft is high temperature and high rotation like the ceramic turbocharger rotor and the ceramic gas turbine. In the case of the above, the residual stress may be released during operation, and the holding force of the combined body may decrease.

On the other hand, with lubricants such as molybdenum disulfide and graphite, since the joint portion is slippery even after the joint, the holding force of the joint portion is weak from the beginning, and the pull-out strength and the torsion resistance are low. There was a problem.

Therefore, in the prior art, the range in which the surface pressure Pm and the press-fit length L can be selected is narrow, high cost is required for the management of the surface pressure, and the demands for high temperature, high rotation and high load cannot be met. Moreover, even if it is within the allowable range, the residual stress concentrated near the fitting end during press-fitting is very high, so that the strength of the ceramic is deteriorated.

An object of the present invention is to solve the above problems and to provide a combined body of ceramics and metal which can prevent galling at the time of press-fitting and can maintain a strong bonding force with little residual stress even after press-fitting. Especially.

[0010]

A first means is a method of manufacturing a combined body in which a lubricant is applied to a joint surface between a ceramic member and a metal member to press-fit the ceramic member into a recess or a through hole of the metal member. In, the main component of the lubricant,
It is a carboxylic acid, a carboxylic acid salt, a carboxylic acid derivative or a carboxylic acid substitution product (hereinafter, also referred to as “carboxylic acid etc.”), and the surface pressure Pm generated between the bonding surfaces and the press-fit length L are as follows:
After press-fitting both members under the condition of satisfying the formula 10 ≦ Pm ≦ 100 [kgf / mm ² ] 30 ≦ Pm · L [kgf / mm], the friction coefficient at the time of press-fitting of the part coated with lubricant is to be removed. It is characterized in that heat treatment is performed until the friction coefficient becomes large.

[0012] Similarly, the second means is a method for producing a combined body in which a lubricant is applied to the joint surface between the ceramic member and the metal member to press-fit the ceramic member into the recess or through hole of the metal member, and After the components are a carboxylic acid, a carboxylic acid salt, a carboxylic acid derivative or a carboxylic acid substitution product, and both members are press-fitted under the conditions that the contact pressure Pm generated between the bonding surfaces and the press-fit length L satisfy the above two expressions, The bonding surface is heat-treated at a temperature at which a majority of the lubricant is decomposed, volatilized, or changed into a low-slipping substance and the metal member is not deteriorated.

What is desirable in these first and second means is a method of performing heat treatment in the temperature range of 100 ° C to 600 ° C.

[0013] Also desirable is a manufacturing method characterized in that the ceramic member is a turbine blade boss and the metal member is a turbine shaft. , For example, a rocker arm tip, a sliding portion with a tappet cam, and a ceramic shaft portion of a boring bar, while the metal member includes, in addition to the turbine shaft, for example, a rocker arm arm, a tappet body, The metal support part of a boring bar is mentioned.

The carboxylic acid is, for example, stearic acid, abietic acid, dextropimaric acid, and the carboxylic acid salt is, for example, sodium stearate,
The carboxylic acid derivative is, for example, a solid ester called oxidized microwax.

[0015]

[Function] A carboxylic acid or the like as a lubricant component exerts a sufficient sliding action upon press fitting. Therefore, if the surface pressure is in a range that satisfies the above two expressions, galling is suppressed even under high surface pressure.

Further, when a carboxylic acid or the like as a lubricant component is heat-treated after press-fitting, a majority of it is decomposed, volatilized or changed into a low-lubricity substance, and when it is easily pulled out from the friction coefficient at the time of press-fitting. Can be adjusted to increase the coefficient of friction. Therefore, if the surface pressure is within the range that satisfies the above two expressions, the holding force of the combined body can be increased even under a low surface pressure.

The heat treatment temperature is preferably 100 to 600 ° C. It is preferable that many metal members such as carbon steel, alloy steel, SUS, heat resistant steel, Incoloy 903, Kovar, aluminum alloy and magnesium alloy do not undergo deterioration such as blunting. Because.

[0018]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a ceramic-metal combination 1 of the present embodiment.
FIG. The combined body 1 is a fitting body of the ceramic member 2 and the metal member 3.

This bonded body 1 has a diameter of silicon nitride =
10 mm cylindrical ceramic member 2 and fitting part outer diameter D
= 17 mm low thermal expansion alloy steel (for example, Incoloy 90
3) with a bottomed cylindrical metal member 3 in the atmosphere,
It is joined by press fitting at room temperature, and a fitting recess 4 which is a cylindrical space is formed at one end of the metal member 3 for joining.

On the basis of this shape, the surface of the inner peripheral surface of the fitting recess 4 which contacts the ceramic member 2, that is, the length L of the connecting surface 5 of the metal member 3 (same for the ceramic member 2 side) L and the connecting surface. The surface pressure Pm was changed variously and press-fitted.

The surface pressure Pm was obtained by substituting numerical values into the following formula 1.

[Equation 1] Next, examples of press-fitting in various shapes will be described.

-Example 1 and Comparative Example 1-A 18% aqueous solution of stearic acid was applied as a lubricant at the time of press-fitting on the bonding surfaces of both the ceramic member 2 and the metal member 3, and then the press-fitting length L = 4 mm was made constant, and the table By performing press-fitting at a predetermined surface pressure Pm shown in 1 and performing heat treatment at 350 ° C. for 1 hour in the atmosphere to reduce the sliding effect of the lubricant, a combined body 1 of 6 types of ceramics and metal was manufactured. However,
The ultra-high surface pressure of Pm = 100 kgf / mm ² exceeds the proof stress of the concave portion 4 of the metal member 3 at the fitting diameter = 10 mm, and causes plastic deformation of the metal. Therefore, Pm = 100k
Only in the case of gf / mm ² , the ceramic member 2 having a diameter of 4 mm was used.

For comparison, five types of comparative conjugates were produced under the same conditions as the above conjugate 1, except that diesel engine oil was used as the lubricant instead of the aqueous stearic acid solution. However, in the case of ultra high surface pressure condition of Pm = 100,
I could not press fit.

Next, for the conjugate 1 and the comparative conjugate,
A cooling / heating cycle test in which 250 cycles of holding at 400 ° C for 50 minutes and holding at -100 ° C for 30 minutes were set as one cycle was performed.

Table 1 also shows the results obtained by measuring the twist resistance and the bending resistance of the bonded body 1 and the comparative bonded body after the thermal cycle test by the methods described below. Also, the relationship between the torsional strength and bending resistance and the surface pressure Pm is plotted in FIG.

(Method of measuring anti-twist strength) The metal member 3 was fixed, a rotational force in the circumferential direction was applied to the ceramic member 2 at room temperature, and the twist torque when the ceramic member 2 started to rotate was measured.

In the torsion strength column of Table 1, ⊚, ○, Δ and × indicate that the torsion torque [unit: kg · m] is 6 or more, 3 or more and less than 6, 2 or more and less than 3 and less than 2, respectively. Show.

(Method of measuring flexural strength) 40 kgf / mm ² supporting the metal member 3 from the side surface of the ceramic member ^2.
The following static load was applied, and the cantilever bending stress value when the ceramic member 2 started to break was measured.

In the bending strength column of Table 1, ◎, ○, △ and ×
Is the cantilever bending stress value [unit: kgf / m
m ² ] is 40 or more, 20 or more and less than 40, 10 or more and less than 20 and less than 10.

[0030]

[Table 1] As can be seen from Table 1, the bonded body of the example can be press-fitted without causing galling even under high surface pressure,
Even after the joining was completed, it had excellent twist resistance and bending resistance.

On the other hand, in the case of the comparative conjugate, Pm
≦ 10 kgf / mm ² and Pm · L ≦ 40 kgf / mm
The torsional strength is extremely low under the low surface pressure of, and Pm ≧
35 kgf / mm ² and Pm · L ≧ 140 kgf / mm
Under high surface pressure, both the torsion resistance and the bending resistance were extremely low. It is considered that this is because under low surface pressure, the residual stress was released during the thermal cycle test, and the holding force of the joint was lowered. Also, under high surface pressure, the friction coefficient at the time of press-fitting became too high, and a large residual stress was generated at the mating end, and due to fatigue during the thermal cycle test, microcracks were generated at the mating end. Conceivable.

-Example 2 and Comparative Example 2-A 18% aqueous solution of stearic acid was applied as a lubricant to the bonding surfaces of both the ceramic member 2 and the metal member 3 as a lubricant at the time of press fitting, and then the surface pressure Pm = 20 kgf / mm ² was kept constant. Then, press-fitting was performed at a predetermined press-fitting length L shown in Table 2, and heat treatment was performed at 350 ° C. for 1 hour in the atmosphere to reduce the sliding effect of the lubricant, whereby a combined body 1 of 6 types of ceramics and metal was manufactured. .

For comparison, five types of comparative conjugates were prepared under the same conditions as the above conjugate 1, except that diesel engine oil was used as the lubricant instead of the aqueous stearic acid solution.

Pm = 100 kgf / mm ² and Pm
・ L = 400 kgf / mm ultra high surface pressure
There was a large amount of galling when press-fitting, and the press-fitting load rapidly increased, so it was not possible to press-fit until the end.

The joint 1 and the comparative joint were subjected to a thermal cycle test under the same conditions as in Example 1, and then the torsional strength and flexural strength were measured by the method shown in Table 1 and the results are shown in Table 2. Also described in. Also, the relationship between the torsional strength and bending resistance and the surface pressure Pm is plotted in FIG.

[0036]

[Table 2] As can be seen from Table 2, the bonded bodies of the examples can be press-fitted without causing galling even if the press-fitting length is long, and conversely, even if the press-fitting length is short, excellent twisting strength and resistance after completion of bonding are achieved. It had bending strength.

On the other hand, in the case of the comparative joint, when the press-fit length is short, that is, Pm · L ≦ 30 instead of the surface pressure, the twist resistance is remarkably low, and Pm · L ≧ 100 instead of the surface pressure.
When the press-fit length was long, both the torsion resistance and the bending resistance were extremely low. It is considered that this is because when the press-fit length was short, the residual stress was released during the thermal cycle test, and the holding force of the joint was lowered. Also, when the press-fit length is long, the press-fit load during press-fitting becomes too high and a large residual stress occurs at the mating end, and fatigue during the thermal cycle test caused microcracks at the mating end. It is believed that there is.

-Example 3 The bonded body obtained by the manufacturing method of the present invention is not limited to the simple shape as shown in Examples 1 and 2. For example, when the ceramic member 2 is a boss of a turbine blade and the metal member 3 is a turbine shaft which is connected to the boss to transmit a rotational force to a compressor wheel, an oil ring groove 32 is formed on the outer periphery of the metal member 3 as shown in FIG. Also, the seal ring groove 33 is provided, and the outer diameter of the metal member 3 differs depending on the fitting direction.

In the case of such a conjugate, determined the surface pressure Pm _n from Equation 1 for different parts of the outer diameter, each of the surface pressure Pm _n
Can be substituted into Equation 2 to calculate the average surface pressure Pm. If the average surface pressure Pm and the press-fit length L satisfy the conditional expression of the present invention, the effect of the present invention is produced.

[0040]

[Equation 2]

As described above, according to the manufacturing method of the present invention,
Since a lubricant with high lubricity is used during press-fitting, galling can be prevented even if the surface pressure is high, and since the lubricant deteriorates or decreases after press-fitting, even if the surface pressure is low, there is little residual stress and a strong bond strength. It is possible to provide a combined body of ceramic and metal capable of maintaining the above. When the combined body of the present invention is applied to a turbocharger rotor, high temperature,
Can withstand high rotation and high load.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a combined body of ceramics and metal in Examples 1 and 2.

FIG. 2 is a graph in which the relationship between the twist resistance and the bending resistance and the surface pressure Pm in Example 1 is plotted.

FIG. 3 is a graph in which the relationship between torsional strength and bending strength and surface pressure Pm of Example 2 is plotted.

FIG. 4 is a cross-sectional view showing a combined body of Example 3.

[Explanation of symbols]

1 ... Combination of ceramics and metal 2 ...
Ceramics member 3 ... Metal member 4 ... Fitting recess 5
..Coupling surface

Claims (4)

[Claims] 1. In a method for producing a combined body in which a lubricant is applied to a joint surface between a ceramic member and a metal member and the ceramic member is press-fitted into a recess or a through hole of the metal member, the main component of the lubricant is carboxylic acid. , A carboxylic acid salt, a carboxylic acid derivative or a carboxylic acid substitution product, and after press-fitting both members under conditions that the surface pressure Pm generated between the bonding surfaces and the press-fit length L satisfy the following formula, A method for producing a combined body of ceramics and metal, comprising heat-treating until the friction coefficient at the time of pulling out is larger than the friction coefficient at the time of press-fitting. 10 ≦ Pm ≦ 100 [kgf / mm ² ] 30 ≦ Pm · L [kgf / mm] 2. A method for producing a combined body, wherein a lubricant is applied to a joint surface between a ceramic member and a metal member to press-fit the ceramic member into a recess or a through hole of the metal member, and the main component of the lubricant is carboxylic acid. , A carboxylic acid salt, a carboxylic acid derivative or a carboxylic acid substitution product, and after press-fitting both members under the conditions that the contact pressure Pm generated between the bonding surfaces and the press-fit length L satisfy the following formula, the majority of the lubricant is A method for producing a combined body of ceramics and a metal, which comprises heat-treating a joint surface at a temperature at which a metal member is decomposed, volatilized or converted into a low-slidability material and the metal member is not deteriorated. 10 ≦ Pm ≦ 100 [kgf / mm ² ] 30 ≦ Pm · L [kgf / mm] 3. The method for producing a combined body of ceramics and metal according to claim 1, wherein the temperature of the heat treatment is 100 ° C. to 600 ° C. 4. The method for manufacturing a combined body of ceramics and metal according to claim 1 or 2, wherein the ceramic member is a boss of a turbine blade and the metal member is a turbine shaft.