JP3045849B2 - Low thermal expansion alloy composite powder material and its sintered product - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low thermal expansion alloy composite powder material and a sintered product thereof. More specifically, the present invention relates to power machine parts, electronic devices, measuring devices,
Further, the present invention relates to a new low thermal expansion alloy composite powder material which is useful in various fields such as low temperature equipment and can be easily molded by injection molding, extrusion molding, etc., and a molded sintered product thereof.

[0002]

2. Description of the Related Art Conventionally, as a low thermal expansion alloy, a 36Ni invar alloy based on Ni or 32N
An i-4Co super Invar alloy is known, for example, as a power member such as a piston of an internal combustion engine, a standard scale,
It is used in various fields such as a bimetal element, a thermostat element, an IC substrate, or a low-temperature equipment as a measuring equipment such as a block gauge. And these are all produced as steel by melting and rolling, or as powder by melting and spraying,
Used in various embodiments.

[0003] Such an invar alloy or super invar alloy material has a characteristic that its coefficient of thermal expansion is extremely small as 1/5 or less of that of ordinary steel. However, although it is an alloy material having such excellent characteristics, it is necessary to respond to technological innovation in a new era as the demand for lighter, thinner, smaller, lighter, thinner and smaller products has increased in recent years. Is getting harder. In addition, molding of a complicated-shaped product itself was not easy.

Accordingly, the present invention has been made in view of the above circumstances, and has a low thermal expansion function and can be reduced in weight while making use of the excellent characteristics of an invar alloy or a super invar alloy. It is an object of the present invention to provide a new low-thermal-expansion material that can be easily manufactured even with a three-dimensionally complex product.

The present invention solves the above-mentioned problems by providing a low thermal expansion comprising a mixed powder of invar alloy or super invar alloy powder and alumina at a weight ratio of 75:25 to 25:75. An alloy composite powder material is provided. The present invention also provides a low-thermal-expansion alloy composite sintered article characterized by using the composite powder material, mixing and kneading the composite powder material with an organic binder, molding, and sintering after degreasing. I do.

That is, the low thermal expansion alloy composite powder material of the present invention is based on a conventionally known Ni-based invar alloy or super-invar alloy, and at a specific weight ratio, that is, its weight. At a ratio of 75:25 to 25:75, it is mixed with alumina . These mixed powders, molding method and its conditions,
Depending on the sintering conditions, the type of alumina to be mixed, and the like, the particle size and ratio can be within a predetermined range.

(1) Composite powder An invar alloy or a super invar alloy (for example, having an average particle size of 5 to 25 μm) and alumina (for example, having an average particle size of 0.1 to 2 μm) are blended to form a mixed powder.

[0008] Commercially available products are also used as these binders. Mixing can be appropriately performed at about room temperature using various blenders. (3) Kneading After mixing the organic binder, kneading is performed using a heating, pressure kneader or the like.

For example, a temperature of 110 to 180 ° C. and a pressure of 2
８8 kgf / cm ^{2 for} about 0.5 to 3 hours. (4) Molding Next, it is molded into a required shape by injection molding, extrusion molding, press molding or the like. At this time, for example, in injection molding, a temperature of 110 to 200 ° C. and a pressure of 300 to 15
A condition of about 00 kgf / cm ² can be adopted. (5) Degreasing The molded body is degreased.

For example, from room temperature to 450 ° C., average heating rate 5
-30 ° C / hr, a pressure of 500-800 Torr, and the use of nitrogen, argon or the like as a carrier gas are exemplified as conditions for that. Further, it may be in the atmosphere. (6) Sintering Sintering is preferably performed in a vacuum atmosphere, for example, at a temperature of 450 to 1450 ° C. and an average heating rate of 80 to 130.
C./hr and a pressure of about 1.0.times.10.sup.- ^{4 to} 1.0.times.10.sup.- ³ Torr.

For example, by the above-described process, even a product having low thermal expansion property, light weight, and complicated three-dimensional shape can be easily obtained as a sintered product.

[0012]

The present invention will be described below in more detail with reference to examples. First, as a Super Invar alloy having the composition shown in Table 1, the average particle diameter is 13.7 μm. E. FIG. T. Alumina having a specific surface area of 0.28 m ² / g and a specific gravity of 8.05 was used as the alumina shown in Table 2. Average particle size 0.23 μm E. FIG. T. A specific surface area of 14.0 m ² / g and a specific gravity of 3.95 are mixed in a weight ratio of 65:35 to obtain a low thermal expansion alloy composite powder material.

[0013]

[Table 1]

[0014]

[Table 2]

This mixed powder is mixed with about 12% of a thermoplastic resin binder by a V blender at room temperature,
Furthermore, the temperature of 150 ° C,
The mixture is kneaded under a pressure of 6 kgf / cm ² for 2 hours. Then 160
At a temperature of ° C., it was injection molded at a pressure of 800 kgf / cm ^2. Thereafter, the substrate was heated to 450 ° C. at an average temperature rising rate of 25 ° C./hr, and degreased in an atmosphere of 760 Torr and argon gas. Then, at an average heating rate of 100 ° C./hr, 141
It was heated to 0 ° C. and sintered under a vacuum of 2.5 × 10 ⁻⁴ Torr for 1.5 hours.

Further, sintering was carried out at temperatures of 1360 ° C. and 1380 ° C. in the same manner to obtain respective sintered products. Table 3 shows the results of evaluating the thermal expansion coefficient of each of the sintered products by changing the heating temperature. In the case of a sintered product at 1410 ° C., it can be seen that low thermal expansion characteristics equivalent to or higher than that of a conventional steel material made of a Super Invar alloy are obtained.

Table 4 shows the evaluation results of the bending strength and the flexural modulus in comparison with alumina alone .
It can be seen that the sintered product of the present invention has better ductility than alumina alone .

[0018]

[Table 3]

[0019]

[Table 4]

Further, the density of the sintered body was evaluated. The result was as shown in FIG. It turns out to be much lower and lighter than Super Invar alloy (8.05). FIG. 3 is an SEM image of a fractured surface of a molded article of the present invention. 4 and 5, the white portions indicate the Invar alloy phase and the black portions indicate the alumina phase. It can be seen that the structure is dense and has a uniform structure without any bending.

As described in detail above, according to the present invention, the sintering temperature range is excellent with low thermal expansion, light weight, and
Since mined wide, a three-dimensional complex shape article is molded containers <br/> easy also, the low thermal expansion alloy composite powder ductility is good, its low molded sintered article is provided as compared with alumina alone .

[Brief description of the drawings]

FIG. 1 is a block diagram showing steps up to sintering of the present invention.

FIG. 2 is a correlation diagram between a sintering temperature and a density as an example.

FIG. 3 is a SEM image of a fractured surface of a molded body.

FIG. 4 is a microstructure diagram of a sintered product.

FIG. 5 is an enlarged (× 400) microstructure diagram of a sintered product.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-2-61026 (JP, A) JP-A-62-280342 (JP, A) JP-A-2-57607 (JP, A) JP-A-3- 94045 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) B22F 1/00-7/08 C22C 1/04-1/05 C22C 33/02

Claims (2)

(57) [Claims] 1. A weight ratio of powder of invar alloy or super invar alloy to alumina of 75:25 to 25:75.
A low thermal expansion alloy composite powder material comprising a mixed powder. 2. A low-thermal-expansion alloy composite sintered product obtained by molding a mixture / kneaded product of the composite powder material and an organic binder according to claim 1 and sintering the mixture after degreasing.