JP3119981B2 - Combined body of ceramic member and metal member and method of combining the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic / metal bonded body in which a ceramic member and a metal member are bonded by mechanical means, and to a bonding method therefor. In particular, the present invention relates to a coupling body and a coupling method suitable for coupling a ceramic rotary body and a metal shaft used for a turbocharger rotor, a gas turbine, a drill, and the like.

[0002]

2. Description of the Related Art Ceramics such as sialon, silicon carbide, alumina, and zirconia have excellent mechanical strength such as wear resistance and high-temperature strength, heat resistance, and corrosion resistance. It is attracting attention as a high-temperature structural material or wear-resistant material for parts for use. However, ceramics are generally hard and brittle, so that their formability is inferior to metal materials. Further, the resistance to the impact force is weak due to poor toughness. A further disadvantage is that the heat transfer is significantly worse than metal materials.

[0003] Until now, turbocharger rotors,
Rotating bodies used in gas turbines, drilling drills, and the like are exposed to severe operating conditions such as high-temperature high-speed rotation and wear rotation, and thus Ni-based heat-resistant alloys and tool steels have been used.
Recently, high-strength ceramics such as sialon and silicon carbide have been developed, and the use of the above-mentioned rotating body has become active in order to achieve high performance and long life by improving heat resistance and wear resistance. . However, it is difficult to form a mechanical part such as an engine part using only a ceramic material, and it is generally used as a composite structure in which a metal member and a ceramic member are combined. As a result, it has become necessary to firmly couple the rotating body made of ceramic and the shaft made of metal.

Heretofore, as a method of bonding ceramics and metal, there has been known a method of manufacturing a bonded body by means of fitting, ie, press fitting, shrink fitting, cold fitting, or the like, between a ceramic convex portion and a metal concave portion. Temperature at the time of these mating,
There are various reports on the optimum range of the shape and the like. For example, in Japanese Patent Application Laid-Open No. 62-4528, the diameter of the protrusion provided on the ceramic member is set to be 0.2 to 0.8 from the inner diameter of the recess provided on the metal member as the size range after drawing.
%.

[0005]

However, these prior arts all limit the outer diameter of the convex portion, the inner diameter of the concave portion, the temperature at the time of fitting, and the like. In addition to the use environment such as the shape and size of the object, exposed atmosphere, temperature, etc., positioning accuracy represented by centering and deviation from the vertical direction, minute scratches on the contact surface, deformation of metal parts at high temperatures, etc. Therefore, there has been a defect that a highly reliable ceramic-metal combined body cannot be obtained due to insufficient bonding force or excessive plasticity accompanied by plastic deformation upon cooling to room temperature.

In general, ceramic materials have a high Young's modulus and are brittle, so they are not easily deformed, but metallic materials are easily deformed. Therefore, when the ceramic convex portion is press-fitted into the metal concave portion by interference fit such as shrink fitting, the ceramic convex portion is hardly deformed, the metal concave portion is pushed out, and the stress generated at that time is reduced by the ceramic convex portion. It becomes the tightening force. It is necessary to generate this stress uniformly and within a range that does not cause deformation or cracks in the metal part, and to firmly tighten the ceramic part.

In other words, even if the difference between the outer diameter of the ceramic projections and the inner diameter of the metal recesses is increased, different metal materials have different fastening forces, and the recesses are deformed particularly with metal materials having a low yield stress. It is not possible to obtain a combined body having a tightening force. Further, when the difference between the outer diameter of the convex portion and the inner diameter of the concave portion is too large, there is a problem that the ceramic convex portion and the metal concave portion are damaged. That is, in the above-described prior art, it is not possible to obtain a joint body having high reliability and stable fastening force with respect to all ceramic / metal joint bodies.

An object of the present invention is to provide a combined body of a ceramic member and a metal member and a method of combining the same, which can solve the above-mentioned problems and can simplify a positioning jig in a heating furnace at the time of fitting. It is assumed that.

[0009]

The ceramic of the present invention
The metal combined body is a ceramic-metal combined body formed by providing a convex portion on a ceramic member and fitting the convex portion to a concave portion provided on the metal member by fitting, wherein the ceramic convex portion and the metal concave portion are formed. The ceramic member convex portion outer diameter D _c has a two-stage structure, and is defined as a dimension range at room temperature before the ceramic member convex portion is fitted into the metal member concave portion.
The ratio of the difference of the metal concave inner diameter _{D mi (D c -D mi)} × 100
/ D _c , 0.15% or more and 0.5 on the large diameter side
It is characterized by being less than 0% and within the range of 0.50% to 0.85% on the small diameter side.

Further, according to the present invention, there is provided a ceramic / metal bonding method in which a convex portion of a ceramic member is fitted to a concave portion of a metal member by fitting. Along with forming into a structure,
The ratio of the difference (D _c −) between the outer diameter D _{c of the} ceramic member convex portion and the inner diameter D _mi of the metal concave portion is defined as a dimensional range at room temperature before the ceramic member convex portion is fitted into the metal member concave portion. D
_mi ) × 100 / D _c , 0.15 on the large diameter side
% Or more and less than 0.50%, and the small diameter side is processed so as to be in the range of 0.50% or more and 0.85% or less, and the protrusions and recesses of both members are fitted.

[0011]

According to the present invention, general-purpose application to various ceramics and metal materials is achieved by limiting the use conditions such as the shape, size, temperature at the time of fitting, etc., which have been conventionally performed. This has the effect of improving the operability, reducing the effects of scratches on the contact surface and the deviation from the vertical direction at the time of insertion by increasing the number of stages, and simplification of the positioning jig at the time of fitting.

[0012] When actually implementing the present invention, two stages of the ceramic member protruding outside diameter D _c and the metal concave inner diameter D _mi
The difference in specific size range at room temperature about _{(D c -D mi) × 100} / D c of can be set. What is important here is that a ceramic-metal bonded body of any shape and usage conditions can be obtained if a bonded body that falls within the scope of the present invention is manufactured. Even if any of the large-diameter and small-diameter steps are flawed on the inner surface of the metal recess at the time of insertion, the effects on the whole can be reduced by increasing the number of steps, and the deviation from the vertical direction can be corrected.

In the present invention, the ratio (D _c) of the difference between the outer diameter D _c of the convex portion of the ceramic member and the inner diameter D _mi of the concave portion of the metal member.
-D _mi) why × 100 / D _c is limited to 0.85% or less than 0.15%, if the value is less than 0.15%, the fit between the ceramic member and the metallic member surface This is because the pressure, that is, the tightening force is insufficient, and the material may be loosened during use or come off in extreme cases.
It is necessary to raise the temperature to 0 ° C. or higher, which is unsuitable because the possibility of plastic deformation of the metal member is large and the tightening force is reduced.

In the present invention, the outer diameter of the projection made of the ceramic member is set in two stages for the following reason. High precision is required when inserting the metal side (small diameter side) from the ceramic side (large diameter side) in FIG. 2, but at this time, the ceramic side (large diameter side) is an auxiliary We can expect to play a role. Therefore, the positioning accuracy at the time of insertion of the heating furnace which actually performs the shrink fitting connection is greatly reduced. This is because the cost of equipment and the cost of operation when performing the coupling are reduced. At this time, for the two-stage structure, the large diameter side is set to 0.15% or more and less than 0.50%, and the small diameter side is set to 0.50%.
The reason for setting the content in the range of not less than% and not more than 0.85% is determined from the range in which it is easy to perform an auxiliary role in centering the insertion. In addition, the reason why the large diameter side is set to relatively weak tightening and the small diameter side is set to strong tightening is that the metal member has a large thickness on the small diameter side so that deformation is unlikely to occur,
Also, it is possible to alleviate a decrease in the tightening force due to scratches or the like.

[0015]

EXAMPLES Table 1 shows examples of shapes of ceramics and metals before bonding according to the present invention and comparative examples. In the present invention, a two-stage convex shape is used (see FIGS. 1 and 2).

[0016]

[Table 1]

The composition of the ceramic is 5% by weight of Y ₂ O ₃ , 3% by weight of Al ₂ O ₃ , 2% by weight of AlN, and the balance of S
This is a sialon made of i ₃ N ₄ , and SNCM439 steel according to JIS standards was used as a metal material (Table 2).
Described). The dimensions and shape are as follows.
000 mm, and processed so that the inner diameter of the metal concave portion was within the dimensional range shown in Table 1 in accordance with this.
In addition, the outer diameter of the metal concave portion was set to 15.0 mm, and the present invention was limited to the large diameter side.

Regarding the temperature condition, it is actually difficult to carry out the heating without heating the ceramic portion, and it is not possible to maintain the room temperature at room temperature due to a temperature rise from a metal concave portion which is a mating material or a heat transfer from a jig at the time of bonding. it is conceivable that. Therefore, also in this example, the ceramic part was kept at 200 ° C. in advance, and the metal part was kept at 900 ° C., and the temperature difference ΔT = 700 (K). At this time, the dimensional changes calculated from the respective coefficients of thermal expansion are as shown in Table 2.

[0019]

[Table 2]

For example, the actual dimensions of the ceramic projections and metal depressions at room temperature on the ceramic side (large diameter side) shown in Table 1 are 10.000 mm and 9.985 mm, respectively. Applying this to Table 2, after heating each 10.006 mm, 1
0.046 mm. Therefore, a gap of 20 μm is provided at each end to enable insertion.
Similarly, on the metal side (small diameter side) in Table 1, the actual dimensions of the ceramic protrusions and metal recesses at room temperature are 5.000 mm, respectively.
It is processed to 4.960 mm, but after heating, each is 5.0 mm
It becomes 03 mm and 5.016 mm, and is inserted at both ends with a gap of about 6.5 μm. In Comparative Example 2, the actual size of the ceramic convex portion and the metal concave portion at room temperature was 1 respectively.
They are 0.000 mm and 9.910 mm. Applying this to Table 2, after heating, each was 10.006 mm, 10.022 mm
And inserted at both ends with a gap of about 8 μm. However, since the outer diameter of the metal concave portion was 15.0 mm, deformation or misalignment occurred when the ceramic convex portion was inserted, and the torsional torque at room temperature was lower than the value of the present invention. Table 3 shows the torsional torque value at room temperature of each combination. From these results, the conjugate according to the present invention was the best.

[0021]

[Table 3]

A turbocharger rotor for an automobile using the shrink-fitting method of the present invention has been confirmed to be free from breakage in a rotation test at 3500 rpm (room temperature).

The present invention is not limited only to the above-described embodiment, that is, many modifications and changes can be made to the ceramic-metal combined body having the interference structure.
For example, in the above-described embodiment, Sialon was used as a ceramic member, but other ceramics such as silicon carbide, silicon nitride, zirconia, mullite, alumina, and beryllia can be used, and metal members such as Kovar and Incoloy can be used. Low thermal expansion steel or the like can be used. Further, as a fitting method, besides press-fitting, shrink fitting, cold fitting, or a combination thereof can also be used.

[0024]

According to the joining of the ceramic member and the metal member of the present invention, various ceramics and metal materials have versatility due to the effect of setting a plurality of tightening forces, and the inner surface of the metal recess is formed due to the multi-stage structure. An effect of reducing deterioration of positioning accuracy due to scratches or misalignment can be obtained.
INDUSTRIAL APPLICABILITY The present invention is applicable to a composite structure of a ceramic rotating body such as a turbocharger rotor, a gas turbine rotor, and a drill, and a metal shaft.

[Brief description of the drawings]

FIG. 1 shows an example of a conventional one-stage shrink fit connection.

FIG. 2 is a sectional view of a two-stage convex shape used in the present invention.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B23P 11/00 C04B 37/02

Claims (2)

(57) [Claims] 1. A ceramic-metal combined body in which a convex portion is provided on a ceramic member and the convex portion is connected to a concave portion provided on a metal member by fitting, wherein the ceramic convex portion and the metal concave portion are provided. The ceramic member convex portion outer diameter D _c has a two-stage structure, and is defined as a dimension range at room temperature before the ceramic member convex portion is fitted into the metal member concave portion.
The ratio of the difference of the metal concave inner diameter _{D mi (D c -D mi)} × 100
/ D _c , 0.15% or more and 0.5 on the large diameter side
A combination of a ceramic member and a metal member, wherein the combination is less than 0% and the range of 0.50% to 0.85% on the small diameter side. 2. A ceramic / metal bonding method for connecting a convex portion of a ceramic member to a concave portion of a metal member by fitting, wherein the ceramic convex portion and the metal concave portion are formed in a two-stage structure. The ratio (D _c −D) of the difference between the outer diameter D _{c of the} ceramic member convex portion and the inner diameter D _mi of the metal concave portion is defined as a dimension range at room temperature before the convex portion made of the ceramic member is fitted into the concave portion of the metal member. _mi ) × 100 / D _c , processing is performed so as to be in the range of 0.15% to less than 0.50% on the large diameter side and 0.50% to 0.85% on the small diameter side. A method of joining a ceramic member and a metal member, wherein the protrusion and the recess of the member are fitted.