JPS60141801A - Reformed metallic powder - Google Patents

Abstract

PURPOSE:To reform metallic powder having a spherical, flake, dendrite or short wire shape to the metallic powder having an excellent powder characteristic by subjecting said metallic powder to plating thereby changing the shape thereof and connecting the powder particles to each other by the plating metal. CONSTITUTION:The shape of the metallic powder is made into a spherical, flake, dendrite or short wire shape by the kind and powdering method of a metal, by which a large difference is generated in the fluidity, moldability, etc. thereof in the stage of producing the powder consisting of the metal. The powder is made into a slurry and is fluidied uniformly at an extremely low speed so as to contact with the cathode plate in a plating cell, by which the powder is plated in order to eliminate the above-mentioned difference. The plating provides roundness to the sharp pointed parts with the metal plated on the single particles and changes the shape of the powder by connecting the plural metallic particles with the plating metal, thereby contributing to the formation of the powder having the shape that the metal does not possess intrinsically and to the improvement of the fluidity and moldability of the powder as well as deflection strength of the molding thereof.

Description

[Detailed description of the invention] The present invention relates to the modification of various metal powders.

Specifically, plating is performed on raw metal powder to produce individual metal particles with one surface plated (hereinafter referred to as plated single particles), or multiple metal particles connected to each other via a plating layer (hereinafter referred to as connected particles). The purpose is to produce modified metal powder with excellent powder properties such as moldability, fluidity, and uniform mixability.

In recent years, with the development of the powder industry, various powders have become easier to obtain. Along with this, the applications have expanded greatly and the required characteristics have also become more diverse.

That is, the types of metals are Au, Pd, Ag, and N.
i, Ou.

Co, Fe, Ag-Pd, etc. are available, and there are many different shapes such as spherical, scale-like, dendritic, and short linear.

The characteristics of molded bodies (including molded and fired bodies) vary greatly depending on the metal type and grain size, and each has advantages and disadvantages.

For example, single spherical powder has good fluidity but poor moldability and has the disadvantage of poor dimensional accuracy and transverse rupture strength. On the other hand, dendritic powder has good moldability but poor flowability, and when automatically molded, the weight of each product varies, resulting in poor dimensional accuracy of the molded product. Furthermore, in the case of flaky and short linear powder,
There is a drawback that the transverse rupture strength of the product decreases because the individual particles are arranged regularly during molding. Therefore, when creating a molded product, it is important to select a particle shape that matches the purpose of use, and it is impossible to use them indiscriminately. The reason why inexpensive atomized powder (spherical) is hardly used in the production of copper powder-based molded bodies is precisely for the above reason.

In view of the above-mentioned current situation, the inventors of the present invention have conducted various studies and found that the various conventional problems can be largely solved by coating metal powder with metal. In this application, metals also include alloys.

If the present invention is applied, when the raw material powder is fine spherical powder,
The plating operation produces connected particles, which can yield cine-shaped particles. As a result, the entanglement between particles becomes stronger, and moldability can be greatly improved. When the raw material powder is dendritic powder, cine-shaped particles are generated by the plating operation. As a result, the tips of the branches are plated preferentially, so each branch tip becomes rounded. Therefore, the entanglement of individual particles is appropriately relaxed and fluidity is greatly improved.

As a result, it becomes easy to adjust the amount of filling into the mold within a predetermined period of time, and weight changes from side to side of the molded body are greatly reduced. Furthermore,
If the raw material powder is in the form of fine flakes or short lines, connected particles are generated by plating. As a result of this, the individual particles are joined irregularly, and as a result, the regularity of the arrangement of the individual particles 1 during molding disappears, and the intertwining of the individual particles becomes stronger, improving the transverse rupture strength of the molded product.

The properties of the modified metal powder obtained as a result of the plating operation, in particular, the operational factors that determine whether to generate plated single particles or connected particles are the characteristics of the raw metal powder particles (hereinafter referred to as secondary particles). There are size and shape, slurry concentration during plating work, flow and agitation state of particles in slurry, amount of plating on nine particles, and plating method. The optimal values for these factors vary on a case-by-case basis, and although it is impossible to make a definitive quantitative determination, qualitatively, it is important to consider that the primary particle size is small, the slurry concentration is high to a certain extent, and the amount of plating is It is easier to generate connected particles by increasing the number of particles. By plating, the primary particles flowing in the plating solution have many opportunities to come into contact with each other and coexist with some degree of contact, and the particles are uniformly flowing as a whole. This is because it is a necessary condition that makes it easy to connect. Furthermore, it will be understood that if the amount of plating is too small, the particles cannot be connected to each other.

In order to generate plated single particles, the size of the secondary particles should be large to some extent, the slurry concentration should be somewhat low, and the amount of plating should be small. It is desirable that the primary particles flowing in the plating solution have little chance of coming into contact with each other, or that even if they do come into contact, they will immediately repel and separate, and that the entire particle should be in a uniformly flowing state. These are conditions for producing plated single particles.

The plating method is chemical electroless plating using a chemical reducing agent, and metal powder is used as the reducing agent.

There are displacement plating, which causes electroless plating through a displacement reaction, and electroplating, which utilizes an electrolysis reaction. In the case of chemical electroless plating or displacement plating, the plating operation should be carried out by keeping in mind the factors listed above and determining the optimal condition values for each individual case, but in the case of electroplating, Basically, this is a fluid electrolysis of metal particles in a solution, so it is essential that secondary particles are dispersed over the entire surface of the cathode and that they are constantly in contact with the cathode surface and in a state where they are not dispersed. Therefore, special attention is required. For example, when performing fluid electrolytic plating on fine primary particles in a plating tank with the bottom as a cathode, stirring should be done at a speed that allows most of the primary particles to float.

- Since the secondary particles are not plated, stirring must be carried out at a very slow speed to produce uniform flow. As a guide to the conditions for producing connected particles, for example, Q, spherical N1 powder with a particle size of n to 5 μm is chemically electroless N1 powder.
For example, in the case of plating, the raw material N1 powder slurry concentration is 5 to 100 f/l, preferably 20
〜aOt/l, the degree of stirring, that is, the rotation speed of the stirring blade is 30Ω in diameter of the plating tank, and the length and width of the stirring blade are 20Ω, respectively.
0%, 20%, plating liquid volume 1sz, rotation speed 100
〜500 rpm is preferable, and the optimum value is 300〜
4 n Orpm. There was no noticeable difference in the plating bath composition, and the bath composition was known.

Bath temperature is sufficient. The amount of Ni plating is 5 to 80.
wt4 is preferred, but the optimal amount is 30-50 wt
It is 4. In addition, the allowable N in the chemical electroless N1 plating bath
Since the Ni concentration is 0.1 to 0.2 Vt, it is necessary to repeat the plating operation if the necessary Ni amount is insufficient considering the concentration of the raw material N1 powder and the target N1 plating amount.

The method of the present invention will be explained in detail in Examples below.

Example 1 Spherical N1 manufactured by Inco Co., Ltd. with an average particle size of 3μ as raw metal powder
Using powder, N1 is 50% by chemical electroless N1 plating method.
An example of wt% plating will be described.

The plating tank is externally heated and has a diameter of 300%.

Use an enamel container with a height of 400X, and the stirring blade has a length of 1
50% width, 15% width upper wing, and the number of revolutions is 400 rp.
It was fixed at m. Plating bath: Nickel chloride O, 106M
/l, sodium tartrate α32 M/l.

hydrazisulfate y 0.26M/l, 1) H1s (N
8 was used. The amount of raw material N1 powder added was 5.12 because the target N1 plating amount was set to more than 50 wt.
t/l (Amount of N1+" in the plating solution 49. a 4 y
), and it was decided to obtain the desired product in one plating operation. Add a predetermined amount of raw material N1 powder to a predetermined amount of plating solution,
The plating operation was performed while keeping the plating bath temperature at 80 to 83°C. The plating reaction was completed in about 15 minutes, and the plating solution became colorless and transparent. The obtained N1 metal powder was washed with water, dried, and
99.6 f of i-plating powder was obtained. Ni+ in the solution after plating
Since + was less than o, o 1t/, it was easily estimated that the amount of N1 plating was almost the same as the target value.

Obtained Ni50wH6metsukiN1 powder and raw material N1
The appearance of the powder was compared using scanning electron micrographs. As a result of 1°, the raw material N1 powder consisted of almost only single particles, and the surface was like fine and short needle-like crystals. while 50 wtl
The plating powder formed irregularly shaped connected particles in which multiple particles with relatively smooth surfaces were connected vertically, in a cross shape, or in a ball shape.

Example 2 Thickness O, n~1 μm, size 5~20 as raw metal powder
50 μm using the slow stirring fluidized bed method using Rinka Akiyama powder.
An example of wt1Ou plating will be described. The plating bath was a stainless steel beaker with a diameter of 200% and a height of 300%, and the inner surface except the bottom was rubber-lined for insulation. The slow stirring blades are cross-shaped, each with comb tooth-shaped grooves, so that the distance between the tip of the comb teeth and the bottom surface of the plating tank (which becomes the fixed cathode surface) is 2 to 39 mm. I set it. Note that the length of the stirring blade is 195X.

The height was 30'X, the height of the comb tooth-shaped grooves was 2°X, the groove width was 5%, and the tooth width was 3mm. The anode was made of electrolytic copper, had a width of 30%, a thickness of 10%, and a length of 100X (immersion part 50X), and was suspended from the outer surface of the plating tank. Electricity was applied to the bottom of the plating tank by wrapping a copper plate around the outside of the plating tank so that the entire plating tank was connected to the cathode.

Plating bath composition is Ou 50 r/z, H, SO415
0"//L, and the liquid volume was 4.5. The amount of raw material corn powder added was 500 t, the current was 150 A, and the bath temperature was 65 to 70°C.
.

The plating operation was performed at a stirring blade rotation speed of 0.5 rpm.

The Ou-plated Ou powder obtained after energization for 2,76 hours was washed and dried to obtain 999.2 f Ou-plated Ou powder.

As a result of comparing the obtained Ou-plated O powder and the raw material powder in the same manner as in Example 1, it was found that the raw material copper powder was a flake-like powder with almost only a single particle and a highly uneven peripheral part. On the other hand, 50wt
The l Ou plating powder was an irregularly shaped powder consisting of connected particles, in which a plurality of particles with rounded peripheries were joined mainly perpendicularly or obliquely to the flat surface.

The method of the present invention has been described in detail in the Examples above.

Furthermore, in order to show that the present invention is revolutionary, Table 1 shows the results of comparing the characteristics of the powders before and after plating in Examples 1 and 2.

Table 1 Characteristics of powder before and after plating in Examples 1 and 2 As is clear from the examples and Table 1, even if the shape of the raw material powder is different, the powder characteristics can be greatly improved by applying the present invention and modifying it. It can be seen that there is an improvement in

In the above embodiments, the case where the primary particles and the plated metal are of the same type was cited for simple comparison of effects, but a certain modification effect is also expected when the primary particles are plated with a different type of metal.

It goes without saying that the modified metal powder obtained by the present invention can also be used in products manufactured by mixing it with different metal powders.

111 =

[Brief explanation of the drawing]

The figure shows the respective shapes of raw metal powder and modified metal powder when the present invention is applied to raw metal powder of various shapes. Among the heading symbols in the figure, A indicates raw metal powder,
B indicates a modified metal powder, and 1, 2, and 3.4 indicate that the raw metal powder has a spherical shape and a scale-like shape, respectively. Indicates a linear or dendritic case. Patent applicant Nippon Mining Co., Ltd. Agent Patent attorney (7569) Keishi Junyo = 12- Procedural amendment diagram (IA) (IB) b 00oo. (3B) (:SA) , -1, 2...' Hammer "ff 1978
Kazuo Wakasugi, Commissioner of the Japan Patent Office on April 1, 20151, Case description Patent Application No. 245466, filed in 1982, 2, Title of invention: Modified metal powder, 3, Relationship with the amended person's case, Address of patent applicant, Tokyo. No. 1-1, Toranomon 2-chome, Minato-ku Name: Japan Mining Co., Ltd. Representative: Yukio Kasahara 4, Agent: 105 Telephone number: 582-2111 6, Subject of amendment Brief description of drawings in the specification column 1 Drawing Z Contents of the amendment (11 The brief explanation of the drawings will be amended as follows. 4. Brief explanation of the drawings Each figure shows raw metal powder and modified raw metal powder when the present invention is applied to raw metal powder of various shapes. The shapes of the metal powders are shown in Figure 11, Figure 2, Figure 32, and Figure 4, respectively, in the form of two spheres and flakes.
61, 71, and 8 show the shapes of metal powders obtained by modifying the raw metal powders in FIGS. 11, 22, 32, and 4, respectively. ” (2) Revise the drawing as a separate sheet. Above is Figure 1. □Q OO Figure 2 aO Figure 3 tgei ζ-

Claims (3)

[Claims] (1) A modified metal powder characterized in that the metal particles have a single coated particle structure or a multi-particle connected structure with a coated metal deposited using the metal particles as cores. (2) The modified metal powder according to claim 1, wherein the metal particles and the coating metal are the same type of metal. (3) The modified metal powder according to claim 1 or 2, wherein the coating metal is deposited by electroplating.