JP3424555B2 - Composite valve seat and method of manufacturing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to Al or A
Valve seat body made of l alloy or Cu or C
TECHNICAL FIELD The present invention relates to a composite valve seat excellent in thermal conductivity and wear resistance, which is formed by strongly bonding an intermetallic compound layer to a portion of a valve seat body made of a u alloy that includes a valve sealing surface with which the valve is in contact, and a manufacturing method thereof. Is.

[0002]

2. Description of the Related Art Conventionally, a valve seat, which is one of engine parts for automobiles, is made of an iron-based sintered alloy (see Japanese Patent Laid-Open No. 3-158445).

[0003]

However, in recent years, direct injection engines, lean burn engines, etc. have been developed in order to cope with high performance, high fuel consumption and low pollution of automobiles.
The temperature inside the combustion chamber of these engines is higher than that of conventional engines, and at such high temperatures, sufficient wear resistance could not be obtained due to insufficient heat dissipation with the valve seats made of conventional iron-based sintered alloys. .

[0004]

Therefore, the present inventors have
From the above viewpoints, as a result of research to obtain a valve seat that is more excellent in heat dissipation and wear resistance than before, (a) a valve seat body or Cu made of Al or Al alloy that is excellent in thermal conductivity Alternatively, a composite valve seat in which an intermetallic compound layer having excellent wear resistance is formed in a portion including a valve sealing surface with which a valve of a valve seat body made of a Cu alloy abuts is more excellent than a conventional iron-based sintered alloy valve seat. Also has excellent heat dissipation and wear resistance and is suitable as a valve seat for direct injection engines and lean burn engines. (B) The valve seat body made of Al or Al alloy and the intermetallic compound layer are Al or Al. It is bonded via a bonding layer composed of a mixed phase of an alloy and an intermetallic compound, and the thickness of the bonding layer is in the range of 50 to 1000 μm. (C) The valve seat body made of Cu or a Cu alloy and the intermetallic compound layer are joined together via a joining layer made of a mixed phase of Cu or a Cu alloy and an intermetallic compound. It was found that the thickness is preferably in the range of 50 to 1000 μm.

The present invention has been made on the basis of the above findings. (1) An intermetallic compound layer is formed on a portion of a valve seat body made of Al or Al alloy, which includes a valve sealing surface with which a valve contacts. , A composite valve sheet formed by joining through a joining layer having a thickness of 50 to 1000 μm, which is composed of a mixed phase of Al or Al alloy and an intermetallic compound.

Further, according to the present invention, (2) a valve seat body made of Cu or a Cu alloy and an intermetallic compound layer, and a bonding layer made of a mixed phase of Cu or a Cu alloy and an intermetallic compound and having a thickness of 50 to 1000 μm. It is characterized by a composite valve seat which is joined via

Layers of TiAl, Ni ₃ Al, etc. are known as the intermetallic compound layers of the composite valve seat. As one of the methods for forming a layer made of these intermetallic compounds on the surface of a substrate, a laminated compact is prepared in which a mixture of element powders having a composition ratio for forming an intermetallic compound is brought into contact with the substrate. The laminated compact is charged into a resistance heating furnace together with ceramic powder or graphite powder, and after indirectly heating the laminated compact or while heating, the pressure is 30 kgf / cm ^2.
By the above pressurization, there is a method of forming the intermetallic compound layer on the surface of the substrate by the reaction heat and the pressure generated when the mixture of the elemental powders reacts and is synthesized into the intermetallic compound and pressurizing it to manufacture. It is known and it is believed that valve seats can also be manufactured in this way.

However, according to this conventional manufacturing method, the ceramic powder or the graphite powder is heated by the resistance heating element, and the heated ceramic powder or the graphite powder is pressurized to indirectly mix at least 10 element powders. In order to form a TiAl intermetallic compound layer in order to heat and pressurize more than a minute, when TiAl ₂ which is an intermediate product is formed.
And the like, and the crystal grains of the intermetallic compound layer become coarser, so that a TiAl intermetallic compound layer having uniformly fine crystal grains cannot be obtained, and wear resistance of the formed TiAl intermetallic compound layer Sex decreases. Further, since the resistance sheet is indirectly heated for a long time, the valve seat body made of Al or an Al alloy is heated above its melting point, and the valve seat body is melted or deformed to obtain a valve seat having a predetermined shape. In many cases, even if a valve seat with a predetermined shape is obtained,
Sufficient bonding strength between the intermetallic compound layer of the valve seat and the main body of the valve seat was not obtained, and the wear resistance of the obtained intermetallic compound layer was not sufficient.

Therefore, as a result of research on a more effective method for producing a valve seat according to the above (1), the present inventors have found that a mixture of element powders mixed in a composition ratio capable of forming an intermetallic compound is used. A laminated molded body is manufactured by placing the valve seat body made of Al or an Al alloy on a portion including a valve sealing surface with which the valve is in contact, and the laminated molded body is
Maximum voltage: 0.3 to 40 V / cm for 0.1 to 100 seconds, or after direct energization, pressure: 30 to 1
When a pressure of 000 kgf / cm ² is applied, energy can be shockedly applied to the laminated molded body, and the thickness of the bonding layer can be suppressed within the range of 50 to 1000 μm. The bonding strength of the intermetallic compound layer can be further improved, the amount of intermediate products of the intermetallic compound layer can be reduced, and the coarsening of the crystal grains of the intermetallic compound layer can be suppressed to form a uniform fine crystal grain. The inventors have found that it is possible to produce an intermetallic compound layer having excellent wear resistance and obtain a composite valve seat having excellent thermal conductivity.

The present invention has been made based on the above findings, and (3) a valve seat body made of Al or an Al alloy is used as a mixture of element powders mixed in a composition ratio capable of forming an intermetallic compound. Of the valve is brought into contact with a portion including a valve sealing surface, and a laminated molded body is produced, and the laminated molded body has a maximum voltage of 0.3 to 40 V / cm for 0.1 to 100.
After energizing directly for 2 seconds or simultaneously with energizing, pressure: 3
The method for producing a composite valve seat according to (1) above, wherein an intermetallic compound layer is adhesively formed on a portion including a valve sealing surface of the valve seat body by applying a pressure of 0 to 1000 kgf / cm ^2. .

Further, a laminated compact in a state where the mixture of element powders mixed in the composition ratio capable of forming the intermetallic compound and the valve seat body made of Al or Al alloy are in contact with each other is previously prepared as a mixture of element powders. It is preheated to a temperature range where it is not synthesized, and then the preheated laminated molded body has a maximum voltage of 0.
After directly energizing at 3 to 40 V / cm for 0.1 to 100 seconds or simultaneously with the direct energization, pressure: 30 to 1000 kgf /
When the pressure is applied at cm ² , an intermetallic compound layer having a uniform fine grain with less generation of an intermediate product is formed by Al or A
Thickness consisting of mixed phase of l alloy and intermetallic compound: 50 to 1
It is possible to obtain a more excellent valve seat of the present invention which is bonded to an Al or Al alloy valve seat body through a bonding layer of 000 μm.

Therefore, according to the present invention, (4) a portion including a valve seal surface with which a valve of a valve seat body made of Al or an Al alloy is in contact with a mixture of element powders mixed in a composition ratio capable of forming an intermetallic compound. To prepare a laminated compact, and preheat the laminated compact to a temperature range in which the mixture of the elemental powders does not synthesize, and then apply a maximum voltage of 0.3 to 40 to the preheated laminated compact.
After direct energization at V / cm for 0.1 to 100 seconds or at the same time as direct energization, pressure: 30 to 1000 kgf / cm ² is applied to form an intermetallic compound layer on the site including the valve sealing surface of the valve seat body. (1)
The method for producing a composite valve seat described above is characterized.

Further, a mixture of element powders mixed in a composition ratio capable of forming an intermetallic compound is placed on a portion of a valve seat body made of Cu or a Cu alloy including a valve sealing surface with which a valve is in contact, and laminated molding is performed. A body is produced, and a maximum voltage of 0.3 to 40 V / cm is applied to this laminated molded body in an amount of 0.1 to 1
After energizing directly for 00 seconds or while energizing directly, pressure:
When a pressure of 30 to 1000 kgf / cm ² is applied, energy can be shockedly applied to the laminated molded body,
The thickness of the bonding layer can be suppressed within the range of 50 to 1000 μm, the bonding strength between the valve seat body and the intermetallic compound layer can be further improved, and the amount of the intermediate product of the intermetallic compound layer can be increased. To obtain a composite valve sheet having excellent thermal conductivity by producing an intermetallic compound layer having uniform wear resistance by suppressing coarsening of the crystal grains of the intermetallic compound layer while reducing the amount thereof. We have obtained the knowledge that

Therefore, according to the present invention, (5) a portion including a valve sealing surface with which a valve of a valve seat body made of Cu or a Cu alloy is in contact with a mixture of element powders mixed in a composition ratio capable of forming an intermetallic compound. The laminated molded body placed on the substrate was prepared, and the laminated molded body was directly energized at a maximum voltage of 0.3 to 40 V / cm for 0.1 to 100 seconds, or simultaneously with the direct energization, the pressure was 30 to 10
The method for producing a composite valve seat according to (2) above, wherein an intermetallic compound layer is adhesively formed on a portion including a valve sealing surface of the valve seat body by applying a pressure of 00 kgf / cm ² .

Further, the mixture molding of the element powders mixed in the composition ratio capable of forming the intermetallic compound is placed on a portion of the valve seat body made of Cu or Cu alloy including the valve sealing surface with which the valve is in contact, and laminated molding is carried out. A body is produced, and this laminated compact is preheated to a temperature range where a mixture of element powders is not synthesized in advance, and then the preheated laminated compact is subjected to a maximum voltage of 0.3 to 40 V / cm for 0.1 to 100 seconds. After direct energization or simultaneously with direct energization Pressure: 30-1000
When pressurizing at kgf / cm ² , the intermetallic compound layer with less generation of intermediate products and uniform fine grains is formed by Cu.
Or the thickness consisting of a mixed phase of Cu alloy and intermetallic compound:
It is possible to obtain a more excellent valve seat of the present invention which is bonded to Cu or a Cu alloy valve seat body through a bonding layer of 50 to 1000 μm.

Therefore, according to the present invention, (6) a portion including a valve sealing surface with which a valve of a valve seat body made of Cu or a Cu alloy is in contact with a mixture of element powders mixed in a composition ratio capable of forming an intermetallic compound. The laminated molded body placed on the preheated laminated molded body is preheated to a temperature range in which the mixture of the element powders does not synthesize, and then the preheated laminated molded body has a maximum voltage of 0.3 to 40 V.
/ Cm for 0.1 to 100 seconds or simultaneously with the direct energization, a pressure of 30 to 1000 kgf / cm ² is applied to form an intermetallic compound layer on the valve seat body including the valve sealing surface. The method for producing a composite valve seat according to (2) above is characterized.

In the method for manufacturing the composite valve seat according to the present invention, the maximum voltage is 0.3 to 40 V / cm and 0.1 to 1
The direct energization for 00 seconds is that the energization under these conditions can give energy to the laminated molded body shockingly,
Therefore, the thickness of the bonding layer can be suppressed within the range of 50 to 1000 μm, the bonding strength between the valve seat body and the intermetallic compound layer can be further improved, and the intermediate product of the intermetallic compound layer can be formed. This is because it is possible to reduce the amount and suppress the coarsening of the crystal grains of the intermetallic compound layer to form an intermetallic compound layer having uniform and fine crystal grains and excellent in wear resistance. Further, in the valve seat of the present invention, a joining layer formed of Al or a mixed phase of an Al alloy and an intermetallic compound, which is formed between a valve seat body made of Al or an Al alloy and an intermetallic compound layer, or Cu or a Cu alloy is used. Formed between the valve seat body and the intermetallic compound layer
The thickness of each of the bonding layers made of the mixed phase of u or Cu alloy and the intermetallic compound is limited to 50 to 1000 μm, because the thickness of the bonding layer is less than 50 μm, the valve seat body and the intermetallic compound layer are separated from each other. If sufficient bonding strength cannot be obtained and the thickness of the bonding layer exceeds 1000 μm, it is necessary to keep the heating time long, and the Al or Al alloy or Cu or Cu alloy of the valve seat body is an intermetallic compound. It is not preferable because it diffuses into the layer and the crystal grains of the intermetallic compound layer become coarse, and the amount of the intermediate product is increased to reduce the wear resistance of the intermetallic compound layer and reduce the bonding strength. It is a thing.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Average particle size: Ti powder, Fe powder, Ni powder, Al powder, Si powder within the range of 1 to 7 μm,
Co powder and Zr powder were prepared, and these powders were blended in the proportions shown in Table 1, mixed, and molded into a die to have an outer diameter of 3
A mixture of elemental powders having dimensions of 4 mm, inner diameter: 27 mm, thickness: 2 mm was prepared.

On the other hand, pure Al, pure Cu, AC8A (Si:
12.1%, Cu: 1.1%, Ni: 12%, Mg:
0.9%, Fe: 0.3%, the balance is Al alloy consisting of Al), JISA2017 (Cu: 4.0%, M
n: 0.8%, Mg: 0.7%, Si: 0.4%, F
e: an Al alloy containing 0.3% and the balance being Al), or JISC1700 (Be: 1.7%, C
o: Cu alloy containing 0.3% and the balance being Cu)
A valve seat body having an outer diameter of 34 mm, an inner diameter of 27 mm, and a thickness of 5 mm was prepared.

Example 1 A mixture of these element powders was mixed with pure Al, AC8A or J
Laminated bodies A to K are produced by stacking the combination shown in Table 1 on a portion of the valve seat body made of ISA2017 including a valve sealing surface with which the valve abuts, and these laminated bodies A to K are mounted on a graphite mold. Then, a synthetic reaction is caused by directly energizing the laminated moldings A to K at the maximum voltage shown in Tables 2 to 3 for the time shown in Tables 2 to 3, and as shown in Tables 2 to 3. The valve sheets 1 to 11 of the present invention were produced by pressurizing with a pressure, and forming an intermetallic compound layer by adhesion on a portion of the valve seat body including the valve sealing surface with which the valve abuts.

The area ratio of coarse particles having a particle size of 20 μm or more contained in the intermetallic compound layers constituting the valve sheets 1 to 11 of the present invention was measured by a microscope, and the area ratio of the intermediate product was determined by X-ray diffraction. The results of these measurements are shown in Tables 2 to 3 after the phase identification by precipitation and then the microscopic observation, and the thicknesses of the bonding layers of the valve seats 1 to 11 of the present invention were measured by EPMA. The results are shown in Table 2 to Table 3.
It was shown to.

On the other hand, the outer diameter is 3 made of the material of SUH36.
A valve having an umbrella portion of 0 mm was prepared, and the umbrella portion of this valve was kept at 900 ° C. The valve seats 1 to 11 of the present invention shown in Tables 2 to 3 were press-fitted into jigs whose interiors were cooled, and the valves having the umbrella portion held at 900 ° C. were used, and the seating load was 30 kg in a gasoline combustion atmosphere. Number of valve seats: Tested for 100 hours under the condition of 3000 times / min, the maximum wear depth of the intermetallic compound layers of the valve seats 1 to 11 of the present invention was measured, and the intermetallic compound layer was joined to the valve seat body. For the purpose of evaluating the strength, the maximum breaking force of the joint was determined, and the value obtained by dividing the maximum breaking force by the joint area was taken as the shear strength. The measurement results are shown in Tables 2 and 3.

Conventional Example 1 For further comparison, the laminated compacts A to K of Table 1 produced in Example 1 were charged into a graphite mold, and the graphite was pressed under the pressure shown in Tables 4 to 5. 20 by normal resistance heating
It was attempted to indirectly heat the laminated molded articles A to K by heating for a minute to produce the valve seats 1 to 11 in the related art. However, in any case, the valve seat body is melted or deformed to form a valve seat having a predetermined shape. I couldn't get it.

[0026]

[Table 1]

[0027]

[Table 2]

[0028]

[Table 3]

[0029]

[Table 4]

[0030]

[Table 5]

As is clear from the results shown in Tables 1 to 5, the intermetallic compound layers of the valve sheets 1 to 11 of the present invention have few coarse crystals and few intermediate products, and the thickness of the bonding layer is small. It can be seen that is thin, the bonding strength between the valve seat body and the intermetallic compound layer is excellent, and the wear resistance is also excellent.

Example 2 A mixture of elemental powders was laminated in a combination shown in Table 6 on a portion including a valve sealing surface of a valve seat main body made of pure Cu or JIS C1700 in contact with a valve, and laminated moldings L to V were formed. To produce these laminated compacts L to V
Was charged into a graphite mold, and a synthetic reaction was caused by directly energizing the laminated molded bodies L to V at the maximum voltage shown in Tables 7 to 8 for the time shown in Tables 7 to 8 and at the same time.
The valve sheets 12 to 22 of the present invention were produced by pressurizing with the pressures shown in Table 8 and adhering the intermetallic compound layer to the site of the valve seat body including the valve sealing surface with which the valve abuts.

The area ratio of coarse particles having a particle size of 20 μm or more contained in the intermetallic compound layers constituting the valve sheets 12 to 22 of the present invention was measured by microscopic observation, and the area ratio of the intermediate product was determined by X-ray diffraction. Table 7 to Table 8 show the measurement results obtained by performing phase identification by precipitation and then observing with a microscope. Further, the thicknesses of the bonding layers of the valve seats 12 to 22 of the present invention were measured by EPMA and the measurement was performed. The results are shown in Table 7-
The results are shown in Table 8.

On the other hand, the outer diameter is 3 made of the material of SUH36.
A valve having an umbrella portion of 0 mm was prepared, and the umbrella portion of this valve was kept at 900 ° C. The valve seats 12 to 22 according to the present invention shown in Tables 7 to 8 were press-fitted into jigs whose interiors are cooled, and the valve having the umbrella portion held at 900 ° C. was used, and the seating load was 30 kg in a gasoline combustion atmosphere. Number of valve seats: Tested for 100 hours under conditions of 3000 times / minute, the maximum wear depth of the intermetallic compound layer portion of the valve seats 12 to 22 of the present invention was measured, and the intermetallic compound layer was joined to the valve seat body. For the purpose of evaluating the strength, the maximum breaking force of the joint was determined, and the value obtained by dividing the maximum breaking force by the joint area was taken as the shear strength, and these measurement results are shown in Tables 7 to 8.

Conventional Example 2 For further comparison, the laminated compacts L to V shown in Table 6 produced in Example 2 were charged into a graphite mold, and the graphite was pressed under the pressure shown in Tables 9 to 10. 2 by the usual resistance heating the mold
Conventional valve seats 12 to 22 were produced by heating the laminated compacts L to V indirectly by heating for 0 minutes. The same tests as in Example 2 were performed on the conventional valve seats 12 to 22, and the measurement results are shown in Tables 9 to 10.

[0036]

[Table 6]

[0037]

[Table 7]

[0038]

[Table 8]

[0039]

[Table 9]

[0040]

[Table 10]

As is clear from the results shown in Tables 6 to 10, the valve seats 12 to 22 of the present invention have less coarse crystals of the intermetallic compound layer and the intermediate formation as compared with the conventional valve seats 12 to 22. From the fact that the amount of products is small, the thickness of the joining layer is thin, and the shear strength is excellent, it can be seen that the joining strength between the valve seat body and the intermetallic compound layer is excellent, and further the abrasion resistance is excellent.

[0042]

As described above, the valve seat of the present invention can be applied as a valve seat of a new engine developed to cope with high performance, high fuel consumption and low pollution of automobiles. It has excellent industrial effects.

Continuation of front page (56) Reference JP-A-3-107512 (JP, A) JP-A-9-71479 (JP, A) JP-A-57-76214 (JP, A) JP-A-4-118182 (JP , A) JP-A-4-33782 (JP, A) JP-A-7-62528 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) B22F ⁷ /00-7/08 B23K 20/00 F01L 3/02

Claims (6)

(57) [Claims] The site 1. A Al or the valve seat body of a valve made of Al alloy containing abutting valve seal surface, a mixed phase of an intermetallic compound layer, Al or Al alloy and the metal during reduction <br/> compound A composite valve seat, characterized by being bonded via a bonding layer having a thickness of 50 to 1000 μm. 2. A laminate molding in which a mixture of element powders mixed in a composition ratio capable of forming an intermetallic compound is placed on a portion of a valve seat body made of Al or an Al alloy including a valve sealing surface with which a valve is in contact, and laminated molding is performed. A body is produced, and a maximum voltage of 0.3 to 40 V / cm is applied to the laminated molded body in an amount of 0.1 to 100.
After energizing directly for 2 seconds or simultaneously with energizing, pressure: 3
The composite valve seat according to claim 1, wherein the intermetallic compound layer is adhesively formed on a portion including the valve sealing surface of the valve seat main body by applying a pressure of 0 to 1000 kgf / cm ^2. Method. 3. A laminate molding in which a mixture of element powders mixed in a composition ratio capable of forming an intermetallic compound is placed on a portion of a valve seat main body made of Al or an Al alloy including a valve seal surface with which a valve contacts. Body is prepared, this laminated compact is preheated to a temperature range in which the mixture of the element powders is not synthesized, and then the preheated laminated compact has a maximum voltage of 0.
After directly energizing at 3 to 40 V / cm for 0.1 to 100 seconds or simultaneously with the direct energization, pressure: 30 to 1000 kgf /
^{2. The} method for producing a composite valve seat according to claim 1, wherein the intermetallic compound layer is adhesively formed on a portion including the valve sealing surface of the valve seat body by applying a pressure of cm < ² >. The site wherein Cu or the valve seat body of a valve made of Cu alloy containing abutting valve seal surface, a mixed phase of an intermetallic compound layer, Cu or Cu alloy and the metal during reduction <br/> compound A composite valve seat, characterized by being bonded via a bonding layer having a thickness of 50 to 1000 μm. 5. A laminate molding in which a mixture of element powders mixed in a composition ratio capable of forming an intermetallic compound is placed on a site including a valve sealing surface with which a valve of a valve seat body made of Cu or a Cu alloy abuts. After producing a body and directly energizing this laminated compact at a maximum voltage of 0.3 to 40 V / cm for 0.1 to 100 seconds, or simultaneously with the direct energization, pressure: 30 to
The method for producing a composite valve seat according to claim 4, wherein the intermetallic compound layer is adhesively formed on a portion including the valve sealing surface of the valve seat body by applying a pressure of 1000 kgf / cm ² . 6. A laminate molding in which a mixture of element powders mixed in a composition ratio capable of forming an intermetallic compound is placed on a portion of a valve seat body made of Cu or a Cu alloy including a valve sealing surface with which a valve is in contact. Body is prepared, this laminated compact is preheated to a temperature range in which the mixture of the element powders is not synthesized, and then the preheated laminated compact has a maximum voltage of 0.
After directly energizing at 3 to 40 V / cm for 0.1 to 100 seconds or simultaneously with the direct energization, pressure: 30 to 1000 kgf /
The method for producing a composite valve seat according to claim 4, wherein the intermetallic compound layer is adhesively formed on a portion including the valve sealing surface of the valve seat body by applying a pressure of cm ² .