JPH0813708B2 - Ceramic member for joining with metal member - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Object of the Invention (1) Field of Industrial Application The present invention relates to a ceramic member joined to a metal member.

(2) Conventional Technology Conventionally, as this type of ceramic member, a large number of recesses that open to the joint surface are formed in a surface layer portion that constitutes a joint surface with a metal member, and these recesses are used during casting of the metal member. It is known that a metal member is partially filled (see Japanese Patent Laid-Open No. 61-259865).

(3) Problems to be Solved by the Invention However, in the joined body with the metal member using the ceramic member, physical properties such as thermal conductivity, thermal expansion coefficient, and electrical conductivity, and tensile strength are obtained at the joint portion of both members. Mechanical properties such as strength, impact value and fatigue strength change rapidly, so if the joint is subjected to repeated loading for a long period of time or used under severe thermal cycles, the joint will break. There is a problem that it becomes a starting point and the durability of the bonded body is significantly impaired.

In view of the above, it is an object of the present invention to provide the ceramic member that can obtain the joined body having excellent durability.

B. Configuration of the Invention (1) Means for Solving the Problems The present invention relates to a ceramic member joined to a metal member, and a three-dimensional structure including innumerable fine pores filling a part of the metal member. It is characterized in that it has a mesh structure and the diameter of the pores becomes gradually smaller as it goes away from the joint surface with the metal member.

(2) Action When the diameter of the pores is made to have a gradient in the ceramic member as described above, when these pores are filled with a part of the metal member and the metal member and the ceramic member are joined, As the composite of ceramic and metal changes, the physical and mechanical properties of the ceramic member from the joint surface to the entire joint will change with a certain gradient. Can be prevented from deteriorating.

(3) Example A ceramic member having a three-dimensional network structure with innumerable fine pores according to the present invention is manufactured through the following steps. That is, a molded body is formed by using a mixed powder in which a powdery pore-forming substance that can be eluted with an acid, an additive that accelerates the elution treatment of the pore-forming substance, and a sintering aid powder are dispersed in the ceramic powder. These are a step of obtaining, a step of subjecting the molded body to a sintering treatment to obtain a sintered body, and a step of subjecting the sintered body to an elution treatment to dissolve the pore-forming substance after melting and solidification.

As the ceramic powder, Si ₃ N ₄ , Si having a diameter of 10 μm or less can be used.
Single powders of C, ZrO ₂ , Al ₂ O ₃ , sialon, etc., and mixed powders thereof are applicable.

The sintering aid powder is used as necessary to improve the sinterability of the ceramic powder. As the seed powder, Al ₂ O ₃ , Y ₂ O ₃ , MgO, SiO having a diameter of 0.1 to 5 μm are used. ₂ , single powders such as CeO ₂ and mixed powders thereof are applicable.

A powdery pore-forming substance that can be eluted by an acid is used to positively form fine pores in a sintered body to obtain a ceramic member having a three-dimensional network structure with a predetermined porosity. The following applies.

SiO ₂ 24 to 33 wt% B ₂ O ₃ 30 to 50 wt% Al ₂ O ₃ 2 to 15 wt% MgO 2 to 15 wt% K ₂ O 20 wt% or less Na ₂ O 10 to 40 wt% powders After mixing, at least one powder selected from BaO 3% by weight or less, MoO ₂ 3% by weight or less and CeO ₃ 3% by weight or less is added to the mixed powder, and the mixture is obtained through melting and crushing steps. It is a vitreous powder having a diameter of 0.1 to 100 μm.

The reason for limiting the blending amount of each powder as described above is that if the blending amount is deviated from the above, the crystals are deposited on the pore-forming substance to form a non-uniform structure, and elution with acid becomes impossible. Further, in the present invention, as will be described later, melting of the pore-forming material in the sintering process, since it is aimed at the change in the diameter of the pores due to the flow, at the sintering treatment temperature, for example, 800 ~ 1400 ℃, the flow generated from the pore-forming material It is necessary for the body to have a predetermined viscosity, for example 0.1 to 20 cP, and for this reason the compounding amount of each powder is limited as described above.

At least one selected from a boron compound and a phosphoric acid compound is used as an additive that accelerates the elution treatment of the pore-forming substance, and thus the pore-forming component produced by melting and solidifying the substance. In this case, the boron-based compound includes sodium borate, borate such as ammonium borate, boric anhydride (B ₂ O ₃ ), and the like, and the phosphoric acid-based compound includes sodium hexametaphosphate and sodium acid metaphosphate. Metaphosphate, orthophosphoric acid, etc.
Phosphoric anhydride (P ₂ O ₅ ) and the like are included.

This additive has almost no involvement in the sintering process of the ceramic powder, and therefore, it exists in the sintered body and functions to accelerate the elution treatment of the pore-forming component with acid, and thereafter, to the sintered body. It is more eluted with the pore-forming component.

Alumina fibers, silicon carbide fibers (including whiskers), silicon nitride fibers, carbon fibers, etc. may be blended in order to improve the strength of the ceramic member.

The compounding amount of the ceramic powder, the sintering aid powder, the pore-forming substance and the additive is as follows: Ceramic powder 20 to 90% by weight Sintering aid powder 15% by weight or less Pore forming substance 5 to 50% by weight Additive 40% by weight It is as follows.

The reason for limiting the blending amount of the sintering aid powder as described above is that even if the blending amount exceeds 15% by weight, the sinterability of the ceramic powder does not change so much.

Further, the compounding amount of the pore forming substance varies depending on the target porosity of the ceramic member, and the porosity can be adjusted to 20 to 70% by the compounding amount.

Further, the additive improves the mutual diffusibility when joining the ceramic member and the metal member made of aluminum alloy, steel, etc., and also reduces the contact angle of the metal with respect to the ceramic member to significantly improve its wettability. Since it has the effect of improving and increasing the bonding strength, if this effect is aimed at, an additive is added in a slight excess so that it remains as a thin film on the inner surface of the pores of the ceramic member even after the elution treatment. At this time, the blending amount of the additive is suitably 5 to 30% by weight.

When a molded product is obtained by using a mixed powder composed of the ceramic powder, the sintering aid powder, the pore-forming substance and the additive, various molding methods such as a slip casting method, a pressure molding method and an injection molding method are used. . In this case, the molding pressure is
50 to 150 MPa is suitable.

When sintering the molded body, the molded body is 1500 to 22
A one-step sintering method that completes the sintering of the ceramic component by holding it at 00 ° C for 0.5 to 2 hours in one sintering process, or
Primary sintering process of holding at 800-1400 ℃ for 0.5-2 hours and
A two-stage sintering method is adopted in which the sintering of the ceramic components is completed through a secondary sintering treatment in which the temperature is maintained at 1500 to 2200 ° C for 0.5 to 2 hours. When the one-stage sintering method is adopted, the elution treatment is naturally performed after the sintering treatment, but when the two-stage sintering method is adopted, the primary sintering treatment or the secondary sintering treatment is performed. After the binding treatment, the elution treatment is performed.

Since the sintered body after the primary sintering process has an appropriate hardness, it is possible to subject the sintered body to mechanical processing such as lace processing. In this case, the defects caused by machining are
It can be removed by the chemical polishing action of the elution treatment in the next step.

The acid used in the elution treatment is mainly a single acid such as HCl, NHO ₃ or HF, or a mixed acid thereof, and in some cases, a small amount of an organic acid such as carboxylic acid such as CH ₃ COOH or HCOOH is added to the acid. To be done. The elution treatment is performed by immersing the sintered body in an acid solution for a predetermined time. At that time, when ultrasonic vibration of 8 to 24 MHz is applied to the acid solution while flowing, the acid solution spreads to the ceramic component, the pore-forming component and the sintering aid component, and also has the action of promoting the elution treatment of the additive. The elution treatment of impurities contained in the pore-forming component and the ceramic component and the sintering aid component can be completed within a short time.

By the elution treatment on the sintered body, a ceramic member having a three-dimensional network structure having innumerable fine pores can be obtained.

The diameter of the pores of this ceramic member is the largest on the end face side facing downward in the sintering furnace during the sintering process, and gradually decreases as the distance from the end face increases.

 This is probably due to the following reasons.

That is, in the sintering process, when the temperature of the molded body, and hence the glassy pore-forming substance, reaches approximately 1000 to 1200 ° C.,
The substance melts into a fluid with a predetermined viscosity. Then, the fluid descends due to gravity, the rearrangement of the tissue due to the rise of the ceramic component accompanying it, and the re-elevation of the fluid due to the capillary action of the fine gaps generated between the ceramic components due to the descending of the fluid, which causes sintering. The concentration of the pore-forming component in the body is high on the end face side, and gradually decreases as the distance from the end face increases.

By subjecting the sintered body in such a state to the elution treatment, it is possible to form pores having a gradient in diameter as described above.

FIG. 1 (a) shows a ceramic member 1 according to the present invention, which ceramic member 1 is made of silicon nitride,
It has a prismatic shape with a length of 10 mm, a width of 10 mm, and a length of 25 mm. FIG. 1 (b) shows the relationship between the lengthwise distance from the one end face 1a of the ceramic member 1, the maximum diameter of the pores, and the porosity. The line x ₁ corresponds to the maximum pore diameter, and the line x ₂ corresponds to the porosity.

From FIGS. 1 (a) and 1 (b), it can be seen that the diameter and porosity of the pores are the largest on the side of the other end surface 1b of the ceramic member 1, and the diameter of the pores gradually decreases with distance from the other end surface 1b.

FIG. 2 shows the relationship between the porosity and bending strength of the ceramic member.

When the ceramic member obtained by the above method is joined to a metal member, the end face (the other end face 1b in FIG. 1 (a)) on the side where the pore diameter is large serves as the joint face.

The fluid also has a function of removing impurities because it entrains impurities that cause a decrease in strength of the ceramic member and descends.

In addition, in order to improve the wettability of the metal member with respect to the ceramic member, Ti, Cu, A
It is effective to form thin films such as g and B by chemical vapor deposition (CVD) or the like.

[Example I]

Figure 3 shows the internal combustion engine cylinder head 2, a cylinder head main body 3 as the cylinder head 2 is a metal member, absorption of the ceramic member joined to the cylinder head body 3, the exhaust valve seat 4 _1, It has 4 ₂ and.

Both the valve seat 4 _1, 4 ₂ of material, manufacturing method are the same, they since only different from slightly the size of each part, illustrates the preparation of the intake valve seat 4 _1.

As a pore-forming substance, SiO ₂ 28.0 wt% B ₂ O ₃ 37.6 wt% Al ₂ O ₃ 4.6 wt% MgO 3.2 wt% K ₂ O 6.5 wt% Na ₂ O ₂ 0.1 wt% is used to obtain a glassy powder.

Silicon nitride powder 57.5% by weight Maximum diameter 10 μm, average diameter 0.7 μm Pore forming substance 40% by weight Diameter 44 μm or less 30% by weight and diameter 44 to 150 μm
10% by weight of sintering aid powder 2.5% by weight Al ₂ O _{3 with a} maximum diameter of 1 μm and an average diameter of 0.2 μm 1.0% by weight
And 1.5% by weight of Y ₂ O _{3 having a} maximum diameter of 2 μm and an average diameter of 0.4 μm, an organic wax, a dispersant, etc. are added and mixed sufficiently to obtain a mixed powder, and the mixed powder is used for pressure molding by a die. Method, and the molding pressure is 100MPa, the outer diameter a =
An annular molded body 5 of 30 mm, inner diameter b = 19 mm, and length c = 5 mm is obtained.

After the molded body 5 is dried, it is placed on the base of the sintering furnace with one annular end surface 5b facing downward, and the N ₂ flow rate is 30 ml / min.
The molded body 5 is subjected to an organic component removal treatment under the condition of 650 ° C. for 1 hour.

Subsequently, the molded body 5 is subjected to primary sintering treatment under the conditions of N ₂ flow rate of 30 ml / min, 1200 ° C. for 2 hours to obtain a sintered body. The linear shrinkage of this sintered body is 3%.

The sintered body is dipped in an acid solution consisting of 4N HNO ₃ and 0.2% HF and kept for 15 minutes while applying 16 MHz ultrasonic vibration to the acid solution to sinter the pore-forming components, impurities and excess sintering. obtaining a valve seat 4 ₁ having a three-dimensional network structure by eluting the auxiliary component.

The valve seat 4 ₁ is thoroughly washed and then dried, and then the valve seat 4 ₁ is subjected to a secondary sintering treatment at 1700 ° C. for 1 hour to highly sinter the valve seat 4 1. _{Get one} . This is the first valve seat.

The same secondary sintering treatment as described above is performed on the sintered body after the primary sintering treatment similar to the above, and the acid elution treatment similar to the above is performed on the sintered body after the secondary sintering treatment to generate the second valve. Get the sheet.

The two-dimensional porosity and maximum pore diameter of the first and second valve seats are shown in Table I. The pore diameter is measured by using an optical microscope and a scanning electron microscope (SEM). In Table I, 4a and 4b are annular end faces of both valve seats, 4a corresponds to one annular end face 5a of the molded body 5, and 4b corresponds to the other annular end face 5b. Therefore, the diameter of the pore becomes maximum on the side of one annular end surface 4b of both valve seats.

In the first valve seat, the maximum diameter of the pores on the one annular end surface 4a after the acid elution treatment is 104 μm,
The maximum diameter of the pores on the other annular end surface 4b is 140μ.
m.

When both valve seats were cut and the change in the diameter of the pores in the cut surface was examined, it was confirmed that the diameter gradually decreased from one annular end surface 4b to the other annular end surface 4a.

Then, both the valve seat 4 ₁ and the exhaust valve seat
4 ₂ those subjected to predetermined machining preheated to 800 ° C., also absorption, their annular end face 4b in the exhaust side intake,
Those valve seats 4 facing the exhaust ports 6 and 7 respectively
_1, 4 ₂ was placed in a mold, molten metal temperature 700 ° C. of the aluminum alloy (JIS AC4C), were cast the cylinder head 2 under the conditions of filling pressure 200 kg / cm ² for the molten metal, each valve seat
4 _1, 4 ₂ of the aluminum alloy into the pores that have been confirmed to be sufficiently filled.

As described above, Allowing a gradient in pore diameter in both the valve seat 4 _1, 4 _2, the joint between the cylinder head main body 3 and each valve seat 4 _1, 4 _2, valve seat 4 ₁ In this example, in 4 ₂ whole, since physical and mechanical properties change with a certain gradient toward the annular end surface 4b due to complexation with the ceramic and the aluminum alloy into the annular end face 4a, durability due to abrupt changes in their properties It is possible to prevent deterioration of sex.

Example II

FIG. 5 shows a rocker arm 8 for an internal combustion engine. The rocker arm 8 includes a rocker arm body 9 as a metal member,
The rocker arm body 9 is joined to the slipper surface forming body 10 as a ceramic member.

 The manufacture of the slipper surface structure 10 is as follows.

SiO ₂ 27.8% by weight B ₂ O ₃ 37.6% by weight Al ₂ O ₂ 5.2% by weight MgO 8.0% by weight K ₂ O 4.8% by weight Na ₂ O 14.8% by weight BaO 1.0% by weight Other 0.8% by weight was used as a pore forming substance. To obtain a glassy powder. 10 of this vitreous powder
Viscosity at 00-1200 ℃ is 0.6-2.4cP, specific gravity is about 4.5
Is.

Silicon nitride powder 64% by weight Maximum diameter 5 μm, average diameter 0.4 μm Pore forming substance 30% by weight Maximum diameter 20 μm, average diameter 2-3 μm Sintering aid powder 6% by weight Maximum diameter 1 μm, average diameter 0.4 μm Al ₂ O ₃ 2% by weight and Y ₂ O ₃ 4 having a maximum diameter of 0.1 to 2.0 μm and an average diameter of 0.5 μm
An organic wax, a dispersant, etc. are added to the weight% and sufficiently mixed to obtain a mixed powder, and a pressure molding method using a mold is applied using this mixed powder, and the slipper shown in FIG. 6 is applied at a molding pressure of 100 MPa. surface
A main body 11 having 11a and a joining convex portion 1 integrated with the main body 11
A molded body 13 having 2 is obtained.

After the molded body 13 is dried, the molded body 13 is subjected to an organic component removal treatment under the conditions of 650 ° C. and 2 hours.

The molded body 13 is placed on the base of the sintering furnace with the joint protrusion 12 facing downward, and the N ₂ flow rate is 30 ml / min, 0.4 Torr, and the heating rate up to 650 ° C. is 10 ° C./min. Temperature rising rate up to 1200 ℃ 15 ℃ / mi
The molded body 13 is subjected to a primary sintering treatment under the condition of being kept at n and 1200 ° C. for 2 hours to obtain a sintered body.

The sintered body is dipped in an acid solution consisting of 25% HNO ₃ and 0.1% HF and kept for 20 minutes while applying 12 MHz ultrasonic vibration to the acid solution to sinter the pore-forming components, impurities and excess sintering. The auxiliary component is eluted to obtain a slipper surface constituting body 10 having a three-dimensional network structure.

The slipper surface constituting body 10 is sufficiently washed and then dried, and then the slipper surface constituting body 10 is subjected to a N ₂ atmosphere of 50.
Secondary sintering treatment is performed under the conditions of 0 bar, 1700 ° C. and 2 hours to obtain the slipper surface structure body 10 in which sintering has advanced to a high degree.

The slipper surface structure 10 is immersed in an acid solution containing 10% HNO ₃ to remove the clogging caused by the secondary sintering treatment.

Table II shows the two-dimensional porosity and maximum pore diameter of the slipper surface structure 10. In Table II, 12a
Indicates the end face of the joining convex portion 12.

When the change in the diameter of the pores in the cut surface of the slipper face structure body 10 was examined, the end face 12a to the slipper face 11a were examined.
It has been confirmed that the diameter gradually becomes smaller as it reaches, and that the outer peripheral portion of the main body 11 is composed of a shell-like dense layer.

Next, as shown in FIG. 7, a rocker arm body 9 cast from an aluminum alloy (6061 alloy) is installed in a die consisting of an upper die 14 and a lower die 15, and the rocker arm body 9 is used for the slipper surface constituting body. The joining area 9a is heated to about 700 ° C. by the high frequency heating method. In addition, slipper surface structure 10
After preheating to 000 ° C., the joining convex portion 12 is pushed into the joining area 9a by the pressing member 16 at a pressure of 100 kg / cm ² , the slipper surface forming body 10 is joined to the rocker arm body 9, and the rocker arm 8 of FIG. To get

Observation of the cut surface of the rocker arm 8 reveals that each pore is filled with an aluminum alloy.

The use of high frequency heating and pressure bonding as described above is effective in shortening the bonding work time.

(Example III)

FIG. 8 shows a turbine impeller 17 as a ceramic member.
And a joined body 19 of the rotating shaft 18 as a metal member.

 The turbine impeller 17 is manufactured as follows.

The same mixed powder as in Example II, that is, a silicon nitride powder, a pore-forming substance, a sintering aid powder, an organic wax, a slip casting method using a mixture of a dispersant, etc., to a molding pressure of 0.03 MPa. As a result, a molded body having the same shape as the turbine impeller 17, ie, the blade portion 20 shown in FIG. 9A and the joint shaft portion 21 integral with the blade portion 20 is obtained.

A turbine impeller 17 having a three-dimensional mesh structure is formed by subjecting the molded body to the same drying, removal of organic components, primary sintering, acid elution, secondary sintering and removal of clogging as in Example II. To get In the primary sintering process, the molded body is placed in a sintering furnace with the joint shaft portion 12 facing downward.

In the turbine impeller 17, the end surface 20a of the blade portion 20
The relationship between the distance from to the end surface 21a of the joining shaft portion 21 and the porosity and the maximum diameter of the pores is as shown in FIG. 9 (b). line
x ₂ is the maximum diameter of the pores and line x ₃ is the porosity.

In each length of Fig. 9 (a), a = 10mm, b = 25m
m, c = 13 mm, d = 42 mm.

From FIG. 9 (b), from the end surface 21a of the joining shaft portion 21 to the blade portion 20.
It is clear that the diameter of the pores gradually decreases toward the end face 20a of the blade, and in particular, the densification of the blade portion 20 progresses.

Next, as shown in FIG. 10, after the joining shaft portion 21 of the turbine impeller 17 is heated to 1200 ° C. or higher, the end surface 20a side end portion of the blade portion 20 is brought into contact with the fixed support base 23, and the joining shaft portion 21 is also attached. It is sandwiched by the left and right half molds 24.

A steel rotary shaft (carbon steel for machine structure, SACM645) 18 is heated to 1350 ° C through a high frequency heating coil 25, and the rotary shaft is heated.
18 is pushed into the joint shaft portion 21 by the pressure member 26 at a pressure of 50 kg / cm ² , the rotary shaft 18 is joined to the turbine impeller 17, and the joined body 19 of FIG. 8 is obtained.

Observation of the cut surface of the bonded body 19 reveals that the pores of the bonded shaft portion 21 are filled with steel. Then, the joint portion 19 in which the joint shaft portion 21 and the steel are combined
In a, fracture toughness value (K _IC ) 13 to 15 (average 15), bending strength
It shows a high value of 50 to 70 kg / cm ² (average 58 kg / cm ² ).

In this way, it is effective to eliminate stress concentration points by increasing the axial length of the joint portion 19a and avoiding the occurrence of a clear joint interface due to changes in the diameter of the pores.

In addition, since the joint portion 19 is a composite of ceramics and steel, it has good thermal conductivity, and therefore has excellent durability under severe thermal cycles.

Example IV

Another example of manufacturing the slipper surface structure 10 similar to that of Example II will be described.

Silicon nitride powder 37 parts by weight Maximum diameter 10 μm, average diameter 1 μm weight ratio 6:
Powder mixed with No. 4 Pore forming substance of the same material as in Example II 55 parts by weight 10 parts by weight having a diameter of 150 to 250 μm, diameter 100 to 150 μm
10 parts by weight, 15 parts by weight having a diameter of 44 to 100 μm, and 20 parts by weight having a diameter of 44 μm or less Sintering aid powder 3 parts by weight Al ₂ O _{3 having} an average diameter of 0.4 μm 1 part by weight and an average diameter of 0.4
μm Y ₂ O ₃ 2 parts by weight Ammonium borate 5 parts by weight, organic wax, dispersant, etc. were added and mixed well to obtain a mixed powder, and a pressure molding method using a mold was performed using this mixed powder. When applied, a molding body 13 having a main body 11 having a slipper surface 11a and a joint projection 12 integral with the main body 11 is obtained at a molding pressure of 100 MPa as in FIG.

After the molded body 13 is dried, the joining convex portion 12 is placed downward on the base of the sintering furnace, and the N ₂ flow rate is 30 ml / min, 650.
The molded body 13 is subjected to an organic component removal treatment under the condition of 1 ° C. for 1 hour.

Subsequently, the molded body 13 is subjected to primary sintering treatment under the conditions of N ₂ flow rate of 30 ml / min, 1200 ° C. for 2 hours to obtain a sintered body.

The sintered body is dipped in an acid solution consisting of 15% HNO ₃ and 0.3% HF, and the acid solution is kept for 15 minutes while being subjected to ultrasonic vibration of 16 MHz to maintain pore-forming components, impurities and excess sintering aid. The agent component is eluted to obtain a slipper surface constituting body 10 having a three-dimensional network structure.

The slipper surface structure 10 is sufficiently washed and then dried, and then the slipper surface structure 10 is subjected to a secondary sintering treatment at 1700 ° C. for 2 hours to highly sinter the slipper. The surface structure 10 is obtained.

The slipper surface structure 10 is immersed in an acid solution containing 10% HNO ₃ to remove the clogging caused by the secondary sintering treatment. This is the first slipper surface structure.

The same sintered body after the primary sintering treatment is subjected to the same secondary sintering treatment as the above, and then the sintered body after the secondary sintering treatment is composed of the same 25% HNO ₃ and 0.3% HF. The same acid elution treatment is performed using an acid solution to obtain a second slipper surface structure.

The two-dimensional porosity and the maximum diameter of the pores of the first and second slipper surface constituting bodies are shown in Table III. In Table III, 12a is the end face of the joint protrusion 12.

In the first slipper surface structure, the maximum diameter of the pores on the end surface 12a after the acid elution treatment is 270 μm, and the maximum diameter of the pores on the slipper surface 11a is 30 μm.

The slipper surface structure was cut and the change in the diameter of the pores in the cut surface was examined.
It has been confirmed that the diameter gradually becomes smaller as it reaches, and that the outer peripheral portion of the main body 11 is composed of a shell-like dense layer.

[Example V]

 A method for manufacturing the rectangular parallelepiped ceramic member will be described.

Silicon nitride powder 99% by weight Maximum diameter 4 μm, average diameter 0.7 μm Sintering aid powder 1% by weight Al ₂ O _{3 with} average diameter 0.4 μm and Y ₂ O with average diameter 0.5 μm
0.5% by weight of ₃ is mixed to form a base material.

Base material 50% by weight Pore forming material of the same material as in Example II 40% by weight Maximum diameter 44 μm, average diameter about 20 μm Ammonium borate 10% by weight, organic wax, dispersant, etc. are added and mixed well to form a mixed powder. Using this mixed powder, a dry pressure molding method using a mold was applied, and the molding pressure was 100 MPa and the vertical length was 12 m as shown in FIG.
A rectangular parallelepiped shaped body 27 having m, a width of 14 mm and a height of 85 mm is obtained.

After drying the molded body 27, the molded body 27 was erected in the silicon nitride powder inside the box installed in the sintering furnace with one end face m facing downward, and the N ₂ flow rate was 30 ml / min. 0.6Torr, 650
The molded body 27 is subjected to an organic component removing treatment under the condition of 1 ° C. and 1 hour.

Subsequently, the compact 27 is subjected to a sintering treatment by the primary sintering method under the conditions of N ₂ flow rate of 30 ml / min, 0.6 Torr, 1700 ° C. and 1 hour to obtain a sintered body. The average linear shrinkage of this sintered body is 7%
Is.

The sintered body is dipped in an acid solution consisting of 25% HNO ₃ and 0.3% HF, and the acid solution is kept for 20 minutes while applying ultrasonic vibration of 12 MHz to hold pore forming components, impurities and excess sintering aid. The agent component is eluted to obtain a rectangular parallelepiped ceramic member A having a three-dimensional network structure.

The molded body 27 similar to the above is erected on the sintered silicon nitride plate installed in the sintering furnace with the end face m facing downward, and the organic component removal, the sintering and the acid elution are processed in the same manner as described above. Then, the ceramic member B is obtained.

Further, the ceramic member B is placed under an atmosphere of N ₂ under an atmospheric pressure of 50.
HIP treatment is performed at 0 bar and 1700 ° C. for 1 hour to obtain a ceramic member C that has been highly sintered.

Table IV shows changes in the maximum diameter of the pores of the ceramic members A, B, and C. In Table IV, d to m correspond to the positions shown in FIG. 11, d and m correspond to both end faces of the compact 27 during the primary sintering process, and the distance between d and e is 5 mm and e to f. , F-g ... k-
The distance between 1 and the distance between 1 and m is 10 mm.

The preparation of EXAMPLE VI] the valve seat 4 _1, 4 ₂ in corresponding annular ceramic member is described.

As a pore-forming substance, SiO ₂ 27.3 wt% B ₂ O ₃ 39.8 wt% Al ₂ O ₃ 6.1 wt% MgO 4.5 wt% K ₂ O 4.6 wt% Na ₂ O 13.2 wt% BaO 2.0 wt% MoO ₂ 0.2 wt% CeO ₃ 2.3% by weight is used to obtain a glassy powder.

Silicon nitride powder 47% by weight Maximum diameter 4 μm, average diameter 0.5 μm Pore forming substance 40% by weight Average diameter 10 μm Sintering aid powder 1.0% by weight Al ₂ O _{3 with} diameter 0.1-1.0 μm, average diameter 0.4 μm and diameter 0.1- Y ₂ O ₃ having a diameter of 2.0 μm and an average diameter of 0.5 μm is added to 0.5% by weight of each, 10% by weight of ammonium borate and 2% by weight of titanium boride powder, and an organic wax, a dispersant and the like are sufficiently mixed to obtain a mixed powder. A pressure molding method using a die is applied using this mixed powder to obtain an annular molded body 28 shown in FIG. 12 at a molding pressure of 100 MPa. The dimensions of the molded body 28 are as follows. That is,
The outer diameter n of one annular end face 28a is n = 34.1 mm, and the inner diameter p is 22.
7mm, outer diameter g of the other annular end surface 28b = 21.1mm, inner diameter r
= 31.6 mm.

After the molded body 28 was dried, it was placed on the base of the sintering furnace with its one annular end surface 28a facing upward, and the N ₂ flow rate of 30 ml / mi.
Under the condition of 1 hour, the molded body 28 is subjected to the organic component removal treatment.

Subsequently, the compact 28 is subjected to primary sintering treatment under the conditions of N ₂ flow rate of 30 ml / min, 0.6 Torr, 1200 ° C., and 2 hours to obtain a sintered body.

The sintered body was dipped in an acid solution consisting of 4N HNO ₃ and 0.1% HF and kept for 15 minutes while applying 16 MHz ultrasonic vibration to the acid solution to sinter pore-forming components, impurities and excess sintering. The auxiliary component is eluted to obtain an annular ceramic member having a three-dimensional network structure.

The ceramic member is sufficiently washed and then dried, and then subjected to secondary sintering by HIP treatment under the conditions of 500 atm, 1750 ° C. for 1 hour to obtain a highly sintered ceramic member. This is the first ceramic member.

The same secondary sintering treatment as described above is applied to the sintered body after the primary sintering treatment similar to the above, and the acid elution treatment similar to the above is performed to the sintered body after the secondary sintering treatment to obtain the second ceramic. Get the members.

Table V shows the dimensional changes of the outer diameter and the inner diameter and the total linear shrinkage in the first and second ceramic members.

Instead of the silicon nitride powder, the same amount of silicon carbide powder (maximum diameter 2 μm, average diameter 0.4 μm) was used.
The other compounding materials and their compounding amounts are made the same as above, and the first and second ceramic members are obtained by the same method as described above. However, the temperatures in the first and second sintering processes are 1200 and 1750 ° C., respectively.

Table VI shows the dimensional changes in the outer diameter and the inner diameter of the first and second ceramic members and the total linear shrinkage rate.

In Tables V and VI, the linear shrinkage rate of the silicon carbide ceramic member is smaller than that of the silicon nitride ceramic member because the sintering temperature is low.

The viscosity of the pore-forming substance is extremely low, about 1 cP.

Each of the ceramic members is subjected to the same acid elution treatment as described above to remove the clogging thereof, then washed thoroughly with water and then dried.

After that, each ceramic member was preheated to 800 ° C. and placed in a mold, casting was performed using an Al-Si alloy under the conditions of a molten metal temperature of 760 ° C. and a molten metal filling pressure of 200 kg / cm ² , and a ceramic-
An aluminum alloy composite is obtained.

When the surface and the cut surface of the composite were observed with an optical microscope, a scanning electron microscope, etc., the following results were obtained.

In the silicon nitride ceramic member, the maximum diameter of the pores is 0.5 on the side of one annular end surface 28a having a large linear shrinkage.
Although it is as fine as less than μm, the maximum diameter of the pores is as large as about 40 μm on the side of the other annular end surface 28b having a small linear shrinkage ratio,
Further, the diameter of the pores gradually decreases with increasing distance from the other annular end surface 28b.

In such a ceramic member, the other annular end surface 28
b is the joint surface with the metal member.

In the silicon carbide ceramic member, the change in pore diameter is not clear, unlike the one made of silicon nitride described above, but the pore diameter tends to gradually decrease with distance from the lower annular end face as the linear shrinkage rate changes. is there.

C. Effect of the Invention According to the present invention, since the diameter of the pores in the ceramic member has a gradient as described above, a part of the metal member is filled into the pores to join the metal member and the ceramic member. At this time, the physical properties and mechanical properties of the joints of both members will also change with a certain gradient, thereby alleviating the changes in the two properties at the joints and greatly improving the durability of the joints. You can

[Brief description of drawings]

FIG. 1 (a) is a sectional view of a ceramic member, and FIG. 1 (b).
Is a graph showing the relationship between the distance from one end surface of the ceramic member and the maximum diameter of the pores and the porosity, FIG. 2 is a graph showing the relationship between the porosity and the bending strength, and FIG. 3 is a sectional view of the cylinder head. FIG. 4 is a perspective view of a molded body for a valve seat,
FIG. 5 is a sectional view of a rocker arm, FIG. 6 is a sectional view of a molded body for a slipper surface forming body, FIG. 7 is a sectional view showing a joining work, and FIG. 8 is a joined body of a turbine impeller and a rotary shaft. A front view, FIG. 9 (a) is a cross-sectional view of a turbine impeller, and FIG. 9 (b) shows the relationship between the distance from the end surface of the blade portion to the end surface of the joining shaft portion, the maximum diameter of the pores, and the porosity. Graph, number
FIG. 10 is a sectional view showing a joining operation, FIG. 11 is a perspective view of a rectangular parallelepiped shaped body, and FIG. 12 is a sectional view of an annular shaped body. 1 ... Ceramic member, 3,9,18 ... Cylinder head body as metal member, rocker arm body, rotating shaft, 4 ₁ , 4 ₂ ,
10, 17 ... Intake valve seat, exhaust valve seat, slipper surface structure, turbine impeller as a ceramic member

Claims (1)

[Claims] 1. A ceramic member joined to a metal member, which has a three-dimensional mesh structure including innumerable fine pores filling a part of the metal member, and the diameter of the pores is the same as that of the metal member. A ceramic member for joining with a metal member, wherein the ceramic member is gradually reduced with increasing distance from the joining surface.