JPH058242B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a method for producing copper-coated iron powder for powder metallurgy, which allows the surface of iron powder for powder metallurgy to be easily coated with copper. [Prior Art] Examples of forms conventionally used as materials for iron-copper sintered alloys for powder metallurgy include alloy powders and mixed powders. When alloy powder is used as a sintered alloy material, the particles are produced as iron-copper alloy powder by atomization, etc., so the particles have excellent uniformity, but the hardness of the particles is low. It has the disadvantage of poor moldability due to its high price. In addition, when mixed powder is used, uniform mixing is technically difficult, and the coarser the powder particles are, the more likely they are to cause polarization due to the influence of particle size and shape.
Moreover, the variation in sintered dimensions increases. In order to eliminate these drawbacks, various methods for producing copper-coated iron powder have been proposed. For example, there is a method in which iron powder for powder metallurgy is mixed with fine powder of metallic copper, copper oxide, or a reducing copper compound, and then heat treated in a reducing atmosphere to coat the surface of the iron powder with metallic copper fine particles. However, uniform mixing is required, and heat treatment progresses alloying of some of the coated particles, increasing the hardness of the particles, which adversely affects compressibility, formability, etc. In addition, it is difficult to select the particle size and mix balance between metallic copper, copper oxide, and reducing copper compound particles as copper raw materials and iron powder particles, and if the selection is inappropriate, iron particles and copper particles There is a risk that the adhesion of the product will be significantly reduced. There is also a wet method in which the surface of the iron powder is coated with metallic copper by immersing the iron powder in an aqueous solution of copper salts and displacing metallic iron and copper ions due to the difference in ionization tendency. Examples of aqueous solutions of copper salts include copper sulfate and cupric chloride. However, since the use of copper sulfate involves a chemical substitution reaction between divalent copper ions and metallic iron in a copper sulfate solution, a large amount of metallic iron is eluted into the aqueous solution as ferrous ions. Therefore, an amount of iron powder equivalent to the metal copper coated on the surface of the iron powder is lost, and the cost of the product increases by the amount of iron eluted. Another drawback is that the strength of the sintered body is significantly reduced by changing the shape of the iron powder due to the elution of metallic iron. Furthermore, when using cupric chloride solution,
Of course, the same problem as when using a copper sulfate solution can be considered, but instead of the surface of the iron powder being coated with uniform metallic copper fine particles, the copper is non-uniform and extends in the form of dendrites with poor adhesion. Because of the coating, the copper-coated iron powder produced by the conventional method has poor fluidity and cannot improve the formability, mechanical properties of the sintered body, etc. [Problems to be solved by the invention] Conventional technologies such as alloy powder, mixed powder, and copper-coated iron powder have their advantages and disadvantages, but especially regarding copper-coated iron powder, the above-mentioned copper sulfate and cupric chloride solutions are used. If the surface of the iron powder can be uniformly coated with metallic copper fine particles with less elution of metallic iron and good adhesion than in the case where iron powder is used, its usefulness as a powder metallurgy material can be increased. Moreover, if various etching waste liquids can be used as raw materials for copper to be coated while satisfying such conditions, cheaper materials for powder metallurgy can be obtained. This invention was completed as a result of research to address these problems. [Means for Solving the Problems] This invention uses iron powder for powder metallurgy such as atomized powder and reduced powder, and uses an etching waste liquid mainly composed of cupric chloride produced by etching metal materials; Alternatively, prepare a solution in which cuprous chloride is dissolved in a ferrous chloride solution and/or a sodium chloride solution made by reducing etching waste liquid containing ferric chloride as a main component, and add the powder metallurgy to this solution. In this method, the surface of the iron powder is uniformly coated with metallic copper fine particles by dipping the iron powder and using cuprous chloride as a raw material by a chemical substitution method. More specifically, metallic copper is added to an etching waste solution containing cupric chloride as a main component, and the cuprous chloride in which the cupric chloride is reduced is added to a ferrous chloride solution or/and sodium chloride. This method of producing copper-coated iron powder is characterized by immersing iron powder for powder metallurgy in a reaction solution dissolved in a solution, and coating the surface of the iron powder with metallic copper. In this invention, the raw material for the copper that is actually coated on the iron powder for powder metallurgy is cuprous chloride, and this cuprous chloride is a reaction solution obtained by dissolving it in a solution of ferrous chloride. be. Cuprous chloride, which is the copper raw material, has low solubility in water and is poorly soluble, so cuprous chloride alone cannot be used as a reaction solution by dispersing it in water. Therefore, we took advantage of the property of cuprous chloride to form and dissolve a complex salt in a solution containing a large amount of chlorine ions, such as a ferrous chloride solution or a sodium chloride solution, and used this as the reaction solution. The main purpose of this method is to suppress the formation of a dendrite-like coating of metallic copper that is uneven and has poor adhesion on the surface of iron powder, which occurs when a dicopper solution is used as the reaction solution. . Regarding such a suppressive effect, the proportion of dendrite-like copper deposits tends to increase as the concentration of ferrous chloride or sodium chloride decreases and as the reaction temperature increases. Therefore, for example, if a ferrous chloride solution containing cuprous chloride, which forms a complex salt, is used as the reaction solution, the concentration of ferrous chloride in the reaction solution should be set to 10% (wt%; the same applies hereinafter). The concentration of sodium chloride in the reaction solution is preferably 8% or more, especially 10% or more when a sodium chloride solution is used, and the reaction temperature is 60°C or less, especially 50% or more. It is desirable to carry out the test at temperatures below ℃. When the ferrous chloride and sodium chloride concentrations in the reaction solution are used in a dilute state below the above concentrations, or when the reaction temperature is too high, there is a tendency for dendrite-like metallic copper to adhere to the surface of the iron particles. Along with this, the apparent density and fluidity of the copper-coated iron powder also tend to decrease. Further, as the concentration of cuprous chloride, an appropriate concentration is selected so that the cuprous chloride forms a complex salt in the solution and dissolves. This is calculated from the target amount of copper deposited on the copper-coated iron powder, but on the other hand, it is also considered as the concentration required to form a copper coating by bringing the iron powder immersed in the reaction solution into contact with the solution under sufficient stirring. From these, either ferrous chloride solution or sodium chloride solution,
or cuprous chloride for solutions containing both.
A range of 0.5 to 10% can be said to be suitable. By adding iron powder into the reaction solution obtained as above while stirring it, or by adding the reaction solution into the iron powder and stirring for several tens of minutes, chemical Substitution reactions can be carried out. The iron powder coated with metallic copper is separated from the liquid after the substitution reaction has been completed, washed thoroughly with water until the remaining chlorine ions disappear, separated, and dried to obtain the desired copper-coated iron powder. I can do it. As the iron powder used in this invention, powdered metallic iron obtained by an atomization method, a reduction method, or other methods is used. There is no particular restriction on the particle size of these iron powders, and those having particle sizes that are conventionally used as iron powders for powder metallurgy are used. Here, regarding the amount of metallic copper to be coated on the surface of the iron powder, it is desirable to coat the copper coated iron powder to be a product in a range of 0.5 to 40%. If the above-mentioned coating amount is less than 0.5%, no improvement in the mechanical strength of the product as a sintered body can be expected;
If it exceeds %, the copper coating formed on the iron surface due to the copper substitution reaction becomes thicker, the elution of iron decreases accordingly, and the copper precipitation reaction tends to become less likely to occur, which is undesirable. Next, in the present invention, various etching waste liquids described below can be appropriately used as the reaction liquid. That is, when manufacturing copper printed wiring boards used as materials for electronic devices, etching is performed using an etching agent. As such an etching agent, an etching solution containing ferric chloride as a main component or an etching solution containing cupric chloride as a main component is used. Therefore, these waste liquids are inevitably produced during the manufacture of copper printed wiring boards. In addition, a solution containing ferric chloride as a main component is used as an etching solution for metal materials such as stainless steel, nickel, and cobalt, and as a matter of course, a waste solution is generated as the etching solution is used. The composition of metal compounds present in these waste liquids varies depending on the metal to be etched. For example, the waste liquid generated from an etching agent mainly composed of ferric chloride for copper printed wiring boards contains mainly ferric chloride as a metal compound, and also contains ferrous chloride and cupric chloride. ,
Even if the same etching agent is used for etching stainless steel, nickel, iron, etc., the cupric chloride will not be mixed in. Further, the waste liquid generated from an etching agent for copper printed wiring boards containing cupric chloride as a main component is a liquid that is almost exclusively composed of cupric chloride. This invention effectively utilizes the metal components in such waste liquid, and the main component is ferric chloride used in copper printed wiring boards. Copper is added to reduce the ferric chloride remaining in the solution to ferrous chloride and the cupric chloride to cuprous chloride, and these ferrous chloride and cuprous chloride are used. The reaction solution can be obtained by In addition, metal copper is added to the etching waste solution mainly composed of ferric chloride, which may or may not contain cupric chloride, to reduce the ferric chloride in the solution to ferrous chloride, and Produces cuprous metal,
It is possible to obtain a reaction solution using these methods, and it is also possible to obtain a reaction solution by using a combination of metallic iron and metallic copper depending on the composition of the waste solution. In addition, as mentioned above, metallic copper is added to the etching waste liquid mainly composed of cupric chloride generated by using an etching solution mainly composed of cupric chloride, and the remaining cupric chloride is removed by cuprous chloride. This can be dissolved in a ferrous chloride solution or a sodium chloride solution to obtain a reaction solution, and the iron powder for powder metallurgy is immersed in the reaction solution thus obtained as described above. Copper-coated iron powder can be produced. Furthermore, in the present invention, when immersing iron powder for powder metallurgy in a reaction liquid and forming a coating of metallic copper on the surface of the iron powder for powder metallurgy, the copper-coated iron powder is filtered from the reaction liquid. The ferrous chloride solution in the filtrate can be combined with the etching solution to effectively reuse the ferrous chloride in the filtrate, thereby producing copper-coated iron powder at low cost. be able to. In addition, since the use of a ferrous chloride-containing filtrate causes accumulation of ferrous chloride within the circulation system, it is desirable to carry out the test while drawing a portion of the filtrate out of the system. [Function] The method of the present invention uses various etching waste solutions to form metallic copper on the surface of iron powder using a reaction solution obtained by dissolving the obtained cuprous chloride in a ferrous chloride solution and/or a sodium chloride solution. However, cuprous chloride, which is originally poorly soluble, forms a complex salt in ferrous chloride solution and/or sodium chloride solution and becomes soluble, and due to the difference in ionization tendency, iron powder A uniform coating of metallic copper can be formed on the surface. [Examples] The present invention will be described in detail below with reference to Examples and Comparative Examples. Example 1 Metallic copper is added to 1.5 liters of etching waste solution (CuCl ₂ 24.0%) containing cupric chloride as the main component to reduce cupric chloride to cuprous chloride, which is then converted into cuprous chloride with a concentration of 35%. The reaction mixture was added to 8.5 ml of iron solution and stirred, and the precipitate was filtered to prepare the reaction solution shown in Table 1. Next, 1.9 kg of atomized iron powder was added to the reaction solution, and copper fine particles were attached to the surface of the iron powder to obtain 2.1 kg of copper-coated iron powder. Example 2 Metallic copper was added to 1.5 liters of etching waste solution (CuCl ₂ 24.0%) containing cupric chloride as the main component to reduce cupric chloride to cuprous chloride, which was then converted into a sodium chloride solution with a concentration of 28%. After stirring and filtering the precipitate, the reaction solution was prepared as shown in Table 1. Next, 1.9 kg of atomized iron powder was added to the reaction solution, and copper fine particles were attached to the surface of the iron powder to obtain 2.1 kg of copper-coated iron powder. Example 3 Concentration obtained when depositing copper fine particles on the surface of iron powder
Etching waste liquid mainly composed of cupric chloride (CuCl ₂ 24.0%) in filtrate 8.5% containing 35% ferrous chloride
1.5, further reduce the cupric chloride in the liquid to cuprous chloride using metallic copper, filter it and
Obtain the reaction solution shown in the table, and add atomized iron powder to this reaction solution.
1.9 kg of iron powder was added, and copper fine particles were attached to the surface of the iron powder to obtain 2.0 kg of copper-coated iron powder. Example 4 Etching waste liquid mainly composed of ferric chloride (FeCl ₃ 12.9%, FeCl ₂ 11.5%, CuCl ₂ 5.1%) 10
Metallic iron is added to reduce the remaining ferric chloride to ferrous chloride and cupric chloride to cuprous chloride, and after filtering the precipitate, powdered cuprous chloride is obtained.
700g was added to prepare the reaction solution shown in Table 1. Next, 2.0 kg of atomized iron powder was added to the reaction solution, and copper fine particles were attached to the surface of the iron powder to obtain 2.2 kg of copper-coated iron powder. Example 5 Concentration obtained when depositing copper fine particles on the surface of iron powder
Filtrate 5 containing 35% ferrous chloride and etching waste liquid mainly composed of ferric chloride (FeCl ₃ 12.9%,
FeCl ₂ 11.5%, CuCl ₂ 5.1%) 5 are mixed, metallic iron is added to this to reduce the remaining ferric chloride to ferrous chloride, cupric chloride to cuprous chloride, and precipitate. After filtering, powdered cuprous chloride
Add 700g and prepare the reaction solution listed in Table 1.
2.0 kg of atomized iron powder was added to the reaction solution, and 2.2 kg of copper-coated iron powder was prepared by adhering fine copper particles to the surface of the iron powder.
I got it. Example 6 Etching waste liquid mainly composed of ferric chloride (FeCl ₃ 12.9%, FeCl ₂ 11.5%, CuCl ₂ 5.1%) 10
The ferric chloride and cupric chloride in the solution are reduced to ferrous chloride and cuprous chloride using metallic copper, and the precipitate is filtered to obtain the reaction solution listed in Table 1. 2.1 kg of atomized iron powder was put into the liquid to obtain copper-coated iron powder with copper fine particles attached to the surface of the iron powder. Example 7 Concentration obtained when depositing copper fine particles on the surface of iron powder
Etching waste solution mainly composed of ferric chloride (FeCl ₃ 12.9%,
Add FeCl ₂ 11.5%, CuCl ₂ 5.1%) 3.2, reduce the ferric chloride and cupric chloride in the solution to ferrous chloride and cuprous chloride using metallic copper, and filter the precipitate. A reaction solution as shown in Table 1 was prepared, and 2.1 kg of atomized iron powder was added to the reaction solution to obtain copper-coated iron powder with fine copper particles attached to the surface of the iron powder. Comparative Example 1 2.0 kg of atomized iron powder, which is the same as the atomized final powder used in each of the above examples, was put into a cupric chloride solution with a concentration of 35% to coat copper fine particles on the surface of the iron powder to produce copper-coated iron. Got the powder. The main component composition of the reaction solution in Examples 1 to 7 and Comparative Example 1 and the copper weight (%), apparent density (g/cm ² ), fluidity (sec/50g) of the obtained product,
The particle size distribution (-350 mesh) was as shown in Table 1. In addition, in Table 1, each physical property value was based on the following measurement method. (1) Apparent density (g/cm ² ): Based on JIS Z 2504 (Metal powder apparent density test method), a brass funnel (opening angle
Using a 60° orifice {φ=2.54mm, L=3.2mm}, pour the powder into a cylindrical container (capacity 25±0.05cc) and measure its weight. (2) Fluidity (sec/50g): Measure the amount of powder using the same funnel in accordance with JIS Z 2502 (metal powder fluidity test method).
Measure the outflow time of 50g. (3) Particle size distribution -350 (%); Powder amount: 100 g, sieved using an automatic sieve machine, the sieve was a Tyler type sieve, and the % below the 350 mesh sieve was determined.

[Table] Reference Examples 1 to 7 A specified amount of atomized iron powder was added to the copper-coated iron powder obtained in Examples 1 to 7 and Comparative Example 1, and graphite powder was added to the copper-coated iron powder obtained in Examples 1 to 7 and Comparative Example 1.
0.5%, zinc stearate 0.75%, each blending ratio is Fe-1.5, Cu-0.5, C-0.5, Znst.
diameter at a molding pressure of 7.0t/ ^cm2 .
Three tablets of 18 m/m each were prepared, and the green density (g/cm ² ), Rattler value (%), and sintered body dimensional change rate (%) were measured. This is shown in Table 2. In addition, in Table 2, each physical property value was based on the following measurement method. (1) Green powder density (g/cm ² ): According to JSPM Standard 1-64 (compressibility test method for metal powder), metal powder is compressed in a die under certain conditions, and after the compression is finished, the green powder is This is the density of the green compact calculated by the following formula after being extracted from the mold. P=W/0.785×D ² ×H P: Green density (g/cm ² ) D: Diameter of green compact (cm) W: Weight of green compact (g) H: Height of green compact ( cm) (2) Rattler value: Measures the wear resistance and tip stability of a pressure-formed metal compact according to JSPM Standard 4-64 (Rattler test method for metal compacts). The device consists of a cylindrical cage covered with a bronze mesh with a mesh size of 1190μ, an electric motor to drive and rotate the cage, and a test rotation display device to display the test rotation. The test method is to measure 5 test pieces molded at the same pressure to the nearest 0.01/g, then place them in a basket and after 1000 rotations at a speed of 87±10 rpm, take out the 5 test pieces and weigh them to the nearest 0.01/g. Measure to the nearest digit. The results of the Rattler test for metal powder are calculated using the following formula. S=A-B/A×100 (%) S: Weight reduction rate (%) A: Weight of test piece before test (g) B: Weight of test piece after test (g) (3) Sintered body size Change rate (%): Change in dimension due to contraction or expansion during sintering, expressed as a percentage of the dimension before sintering. Note that the numbers of reference examples in the table correspond to the numbers of examples.

【table】

〔Effect of the invention〕

This invention obtains a liquid in which cuprous chloride is dissolved in a ferrous chloride solution and/or a salt solution from various etching waste liquids, and uses this to coat the surface of iron powder with copper. Less elution of iron powder,
Moreover, copper-coated iron powder with excellent copper adhesion can be obtained easily and at a very low cost, and by using the product obtained by such invention, various properties such as compressibility, formability, and mechanical properties can be obtained. You can obtain excellent mechanical parts. Furthermore, in this invention, the cuprous chloride-containing filtrate obtained when coating the surface of powder metallurgy iron powder with metallic copper is combined with the etching waste liquid and reused as a ferrous chloride solution. Therefore, ferrous chloride can be used effectively, and copper-coated iron powder can be obtained at a lower cost.

Claims (1)

[Scope of Claims] 1 Cuprous chloride, which is obtained by adding metallic copper to an etching waste solution containing cupric chloride as a main component to reduce the cupric chloride therein, is added to a ferrous chloride solution or/and chloride. A method for producing copper-coated iron powder, which comprises immersing iron powder for powder metallurgy in a reaction solution dissolved in a sodium solution, and coating the surface of the iron powder with metallic copper. 2. A patent claim characterized in that the ferrous chloride-containing filtrate obtained when the surface of the iron powder for powder metallurgy is coated with metallic copper is used as part or all of the ferrous chloride solution. A method for producing copper-coated iron powder according to item 1. 3. A reaction solution obtained by dissolving cuprous chloride in a ferrous chloride solution obtained by adding metallic iron to an etching waste solution containing ferric chloride as a main component and reducing the ferric chloride therein. 1. A method for producing copper-coated iron powder, which comprises immersing iron powder for powder metallurgy in a method, and coating the surface of the iron powder for powder metallurgy with metallic copper. 4. A reaction solution obtained by dissolving cuprous chloride in a ferrous chloride solution obtained by adding metallic iron to an etching waste solution containing ferric chloride as a main component and reducing the ferric chloride therein. The iron powder for powder metallurgy is immersed in the powder metallurgy, and the surface of the iron powder for powder metallurgy is coated with metallic copper. The iron-containing filtrate,
A method for producing copper-coated iron powder, characterized in that the copper-coated iron powder is used by mixing it with the etching waste solution. 5. Adding metallic copper to an etching waste solution containing ferric chloride as a main component to reduce the ferric chloride to produce ferrous chloride and cuprous chloride,
A method for producing copper-coated iron powder, which comprises immersing iron powder for powder metallurgy in the obtained cuprous chloride dissolution reaction solution of ferrous chloride, and coating the surface of the iron powder for powder metallurgy with metallic copper. . 6. Adding metallic copper to an etching waste solution containing ferric chloride as a main component to reduce the ferric chloride to generate ferrous chloride and cuprous chloride,
The process consists of immersing iron powder for powder metallurgy in the obtained cuprous chloride dissolution reaction solution of ferrous chloride, and coating the surface of the iron powder for powder metallurgy with metallic copper. A method for producing copper-coated iron powder, characterized in that a ferrous chloride-containing filtrate obtained when the surface is coated with metallic copper is mixed with the etching waste solution.