JPH0551662A - Manufacture of cu-ni alloy sintered body - Google Patents

Abstract

PURPOSE:To easily and stably manufacture a Cu-Ni alloy sintered body having high density and excellent in glossiness and corrosion resistance. CONSTITUTION:This is the method for manufacturing a Cu-Ni alloy sintered body provided with processes in which a composition constituted of the powder of, by weight, 2.5 to 35% Ni and the balance substantial Cu and a binder and having <=45mum average particle size and <=8000wt.ppm oxygen content is subjected to injection molding, and this molded body is subjected to binder removing treatment and is furthermore sintered at the sintering temp. of 900 to 1080 deg.C, and at the temp. rising and temp. dropping rate of <=50 deg.C/min, and after that, this sintered body is taken out at <=200 deg.C furnace temp.

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 Cu-Ni based alloy sintered body which has a high density and is excellent in gloss and corrosion resistance.

[0002]

2. Description of the Prior Art Cu-Ni alloys have significantly better corrosion resistance to most types of atmospheres, natural water, industrial water, sea water, many mineral acids and organic acids than copper, and due to the nickel content, they are alkaline. It also has good corrosion resistance to. Therefore, this alloy is used as a corrosion resistant material for highly corrosive solutions such as turbine blades, condensate pipes using seawater and reaction vessels in the chemical industry. It is also used as a decorative metal because it can be made into various colors by changing the amount of nickel. Conventionally, Cu-Ni alloys are manufactured by precision casting, but the dimensional accuracy of sharp parts is poor, and casting defects are likely to occur, so it is necessary to obtain molded products, especially products with complicated shapes. Has been attempted to be manufactured by a cutting method, a usual powder metallurgy method.

[0003]

However, the cutting method has a high manufacturing cost. On the other hand, the ordinary powder metallurgy method inserts the raw material powder into the mold and performs compression molding by pressing, which results in a three-dimensional complicated process. It is impossible to obtain shaped products.
In addition, since a relatively large raw material powder with an average particle size of about 100 μm is used due to the requirement of compressibility, it is difficult to achieve high density required for glossiness and corrosion resistance. It was also necessary to carry out the cutting process. The object of the present invention is to eliminate the above-mentioned conventional drawbacks, have excellent gloss, corrosion resistance, and if necessary, Cu-Ni that can be easily manufactured even in a complicated shape. It is intended to provide a method for producing a system alloy sintered body.

[0004]

Means for Solving the Problems As a result of earnest research to achieve the above-mentioned object, the present inventor injection-molded a powder having a specific particle size blended in a specific ratio, and debinding the obtained molded product. However, it has been found that the above-mentioned problems can be achieved by further performing a sintering treatment or the like under a specific selected condition. That is, the present invention, Ni is 2.5 to 35 wt%, the balance is substantially composed of Cu, the average particle size is 45μm or less, the oxygen content is
A composition comprising powder and a binder of 8,000 ppm by weight or less is injection-molded, and the obtained molded body is debindered,
Furthermore, the rate of temperature increase and decrease is 50 ℃ / min or less, and the sintering temperature is
Cu- is equipped with a process of performing sintering treatment at 900 to 1080 ° C and taking out the sintered body after the sintering treatment from the furnace at an internal temperature of 200 ° C or less.
Provided is a method for manufacturing a Ni-based alloy sintered body.

Raw Material Powder The starting powder may be an alloy powder having one composition or a mixed powder of two or more powders having different compositions. Further, the Ni content of the powder and the sintered body after sintering needs to be 2.5 to 35% by weight, and preferably 5 to 30% by weight. When the Ni content is less than 2.5% by weight, the corrosion resistance of the obtained sintered body is poor, and when the Ni content exceeds 35% by weight, not only the sintered body becomes white and the gloss decreases but also expensive nickel is used. Since the amount is large, the manufacturing cost is high.

As elements other than Cu and Ni, Fe and / or Mn may be added in an amount of 2.5 wt% or less in order to improve corrosion resistance, but other elements are inevitably contained as impurities. desirable.

The average particle size of the powder must be 45 μm or less, preferably 5 to 20 μm or less. If the average particle size exceeds 45 μm, the fluidity of the composition consisting of this powder and the binder will decrease, making injection molding almost impossible, and even if injection molding is possible, the molded body will sinter. The progress of the process of delaying is delayed. Therefore, the final density of the sintered body is unlikely to increase, and the glossiness and corrosion resistance decrease.

The oxygen content is 8000 ppm by weight or less, preferably 5000 ppm by weight or less. Oxygen content is 8000 weight
When the powder content exceeds ppm, the final density of the sintered body is hard to increase due to the influence of the oxide layer on the surface, and the glossiness and the corrosion resistance decrease.

Binder As the binder, a binder usually used in injection molding powder metallurgy, such as polyethylene, polypropylene or natural wax, can be used. The compounding amount of the binder is preferably 60% by volume or less in the composition after compounding. As a method of removing the binder from the molded body, depending on the type of binder used, heat degreasing,
Although solvent degreasing and other known methods can be used, the heat degreasing apparatus is preferably simpler than that of other methods, and therefore, heat degreasing performed in a nitrogen or hydrogen atmosphere or in vacuum during mass production is preferable.

Sintering treatment When the debindered molded body is subjected to a sintering treatment, the temperature rising / falling rate is 50 ° C./min or less, preferably 20 ° C./min.
And the sintering temperature is 900 to 1080 ℃, preferably 1000
Perform at ~ 1050 ° C. The atmosphere is preferably a non-oxidizing atmosphere, for example, hydrogen or vacuum. Temperature rising rate is 50 ° C
If it exceeds / min, anisotropy will occur during sintering, and the dimensional accuracy of the sintered body will deteriorate. If the cooling rate exceeds 50 ° C / min, the sintered body is likely to be deformed.

If the sintering temperature is lower than 900 ° C., the sintering is difficult to proceed even if it is held for a long time, the final density of the sintered body does not increase, and the glossiness and the corrosion resistance decrease. Moreover, although a high-density sintered body can be obtained at a temperature exceeding 1080 ° C., a liquid phase may appear during sintering, which causes the shape to collapse and the surface to melt, resulting in a predetermined shape and size. Cannot be manufactured. The temperature at which the sintered body is taken out of the furnace after the sintering process is 2
It is performed at 00 ° C or lower, preferably 100 ° C or lower. Take-out temperature is
If the temperature exceeds 200 ° C, the surface of the sintered body will be oxidized and the surface gloss will be lost.

[0012]

Example 1 A Cu-Ni alloy powder having the composition, average particle size and oxygen content shown in Table 1 was used as a raw material powder, and a binder containing natural wax and acrylic resin in a ratio of 6: 4. Was added so as to be 45% by volume, and the mixture was kneaded at 150 ° C., and then pelletized. Injection pressure of these pellets is 1200kg using an injection molding machine
It was injection-molded in a mold under the condition of / cm ² . The obtained molded body
The binder was removed by holding at 300 ° C. afterwards,
Sintering treatment was performed at 1030 ° C. for 1 hour in vacuum (× 10 ⁻³ to 10 ⁻² Torr). At that time, the rate of temperature increase and decrease is 10 ℃ / mi
controlled to n. Then, after taking out the sintered body at 100 ° C., the surface of the sintered body was blasted with glass beads.

The sintered body thus obtained was examined for sintered density, gloss and corrosion resistance. The glossiness was evaluated by visually observing whether or not there is gloss. Corrosion resistance is evaluated in a 5% NaCl aqueous solution with a pH of 6.5 at room temperature (25 ° C) for 24 hours.
After immersion, the presence or absence of rust was visually observed and evaluated. The results are shown in Table 1.

Examples 2 to 7 and Comparative Examples 1 to 8 Sintered bodies were manufactured in the same manner as in Example 1 except that the raw materials and manufacturing conditions shown in Table 1 were adopted in each of the Examples and Comparative Examples. The properties of the obtained sintered body were evaluated in the same manner. The results are shown in Table 1. Each comparative example had the following features, and the following findings could be obtained from the results.

In Comparative Example 1, the Cu content of the Cu-Ni alloy powder was 1% by weight.
Since the composition is less than 2.5% by weight, the corrosion resistance of the sintered body is inferior.

In Comparative Example 2, the Cu-Ni alloy powder has an average particle size of 50.5.
Since the powder used is coarser than 45 μm, the density of the sintered body is low, it has no gloss and the corrosion resistance is poor.

In Comparative Example 3, the Cu--Ni alloy powder has an oxygen content of 95.
Since the powder used is more than 8000 ppm by weight at 00 ppm by weight, the density of the sintered body is low, it has no gloss and the corrosion resistance is poor.

In Comparative Example 4, the heating rate was 70 ° C./min,
Since the sintering was performed at a speed faster than 50 ° C / min, the sintered body was deformed.

In Comparative Example 5, the temperature decreasing rate was 80 ° C./min,
Since the cooling rate was faster than 50 ° C / min, the shape of the sintered body was deformed.

In Comparative Example 6, the sintering temperature is 850 ° C., which is lower than 900 ° C., so that the density of the sintered body is lowered, the gloss is low and the corrosion resistance is poor.

In Comparative Example 7, the sintering temperature was 1100 ° C. and the sintering was carried out at a temperature higher than 1080 ° C. Therefore, melting occurred on the surface of the sintered body.

In Comparative Example 8, the temperature at which the sintered body was taken out of the furnace was 250 ° C., and since the temperature was taken out at a temperature higher than 200 ° C., the color of the sintered body was discolored by oxidation and the glossiness was poor.

[0023]

[Table 1]

[0024]

According to the manufacturing method of the present invention, a Cu-Ni alloy alloy having a high density and excellent gloss and corrosion resistance as compared with those manufactured by the conventional powder metallurgy method is used. It is possible to easily and stably produce a bound body. Since the injection molding method is used, a product having a complicated shape can be easily manufactured.

Claims (12)

[Claims] 1. Ni-2.5 to 35% by weight, the balance being substantially Cu
Consisting of a powder having an average particle diameter of 45 μm or less and an oxygen content of 8,000 ppm by weight or less and injection-molding a composition consisting of a binder, and subjecting the obtained molded body to a binder removal treatment,
Temperature rising / falling rate is 50 ℃ / min or less, sintering temperature is 9
Cu-Ni with the process of performing the sintering process at 0 to 1080 ° C and taking out the sintered body after the sintering process from the furnace at an internal temperature of 200 ° C or less
Method for producing a base alloy sintered body. 2. The method according to claim 1, wherein the powder is an alloy powder having the same composition or a mixed powder of two or more powders having different compositions. 3. The method of claim 1, wherein the powdered Ni
A method in which the content is 5 to 30% by weight. 4. The method according to claim 1, wherein the powder has an average particle size of 5 to 20 μm. 5. The method according to claim 1, wherein the powder has an oxygen content of 5000 ppm by weight or less. 6. The method according to any one of claims 1 to 5, wherein the binder content of the composition is 60% by volume or less. 7. The method according to claim 1, wherein the rate of temperature increase and the rate of temperature decrease are 20 ° C./min or less. 8. The method according to claim 1, wherein the sintering temperature is 1000 to 1050 ° C. 9. The method according to claim 1, wherein the furnace temperature is 100 ° C. or lower. 10. The method according to claim 1, wherein the powder contains 2.5% by weight or less of Ni and Cu.
A method containing Fe and / or Mn and impurities inevitably mixed. 11. The method according to claim 1, wherein the sintering treatment is performed in a non-oxidizing atmosphere. 12. The method of claim 11, wherein the atmosphere is vacuum or hydrogen.