JP4857677B2 - Conductive powder molded body electrode and manufacturing method thereof - Google Patents

Description

  According to the present invention, a pulsed discharge is generated between a conductive electrode and a workpiece, and the electrode material or a material in which the electrode material reacts on the workpiece surface by the discharge energy by the pulsed discharge energy. The present invention relates to an electrode used for discharge surface treatment to form a coating film.

  An electric discharge surface treatment is known in which an electric discharge machining method in a machining fluid is applied to form a film on the surface of a workpiece to enhance corrosion resistance or wear resistance. For example, as one of the studies of hard film formation by discharge surface treatment in machining fluid, film formation experiments using Ti metal and WC-Co cemented carbide for the electrode and workpiece respectively deposited on the workpiece. It is disclosed that the coated film becomes TiC, and this film has a hardness twice or more that of the workpiece (for example, see Non-Patent Document 1). As an electrode used for such a discharge surface treatment, in order to increase the hardness of the coating film, carbon, graphite powder, or carbon by discharge energy is used in a green compact electrode formed by pressing metal powder, metal compound powder or ceramic powder. An electrode in which a substance such as an epoxy-based or paraffin-based adhesive to be generated is mixed is disclosed (for example, see Patent Document 1).

  In addition, as an electrode used for other discharge surface treatment, metal powder or metal compound powder is mixed with epoxy resin or phenol resin as an adhesive to improve moldability, and soft metal is added to reduce electrical resistance and pressurization What was shape | molded is disclosed (for example, refer patent document 2).

  Further, as an electrode used for another discharge surface treatment, an electrode obtained by press-molding an electrically conductive powder into an insulating hard substance such as cBN (cubic boron nitride) is disclosed (for example, Patent Document 3). reference).

WO99 / 047730 pamphlet (5th page) International Publication No. 99/046423 Pamphlet (Pages 5-6) International Publication No. 01/023641 Pamphlet (5th page) Akihiro Goto, 5 others, “Formation of hard coating by electrical discharge machining”, Journal of Electrical Machining Society, 1997, Vol. 31, No. 68, p. 26-31

  Discharge surface formed by mixing conventional metal powder, metal compound powder or ceramic powder with carbon, graphite powder or insulating organic materials such as epoxy or paraffin adhesives that generate carbon by discharge energy. In the electrode for a process, there existed a problem that materials, such as a metal to be used, were limited to the material which can become a carbide | carbonized_material by discharge energy. Furthermore, when an insulator such as an epoxy-based adhesive is mixed, there is a problem in that the electric resistance of the electrode increases with the amount of mixing and it becomes difficult to start discharge. In order to avoid this, it is possible to consider a method in which the adhesive is thermally decomposed and removed after the electrode is pressure-molded and the metal powder is sintered. In this case, it is necessary to heat the electrode in high temperature and vacuum. There is a problem that the electrode forming process becomes complicated.

  Moreover, in the electrode for discharge surface treatment that is pressure-molded by adding a soft metal to lower the electric resistance of the electrode, the problem that it becomes difficult to start discharge can be avoided, but it is unnecessary for the coating formed by the discharge surface treatment. There was a problem that soft metal was mixed.

  Furthermore, in the case of an electrode for discharge surface treatment that is pressure-molded by adding conductive powder to an insulating hard substance, the conductive powder is the same as the workpiece when a coating is formed on the workpiece by the discharge energy. There is a problem that the material constituting the electrode is limited because it is limited to a conductive material that does not react unnecessarily with the material of the composition or the workpiece.

  The present invention has been made to solve the above-described problems, and does not limit the selection of the electrode material, and lowers the resistance of the electrode without performing heat treatment in a high temperature / vacuum. Further, it is possible to obtain a conductive powder molded body electrode for discharge surface treatment in which unnecessary materials are not mixed in a film formed on a workpiece.

The conductive powder molded body electrode according to the present invention is a conductive powder molded body electrode used for discharge surface treatment in which a pulsed discharge is generated between the workpiece and a film is formed on the surface of the workpiece. The material to be coated is at least one of metal powder, metal compound powder, glass powder and ceramic powder, and the material to be coated is a conductive organic material having a π-conjugated bond in the main chain. Dispersed to form a pressure molded body, and the specific resistance of the pressure molded body is 104 Ω · cm or less.
In addition, the method for producing a conductive powder formed body electrode according to the present invention is a method for generating a pulsed discharge between a workpiece and a conductive surface used for a discharge surface treatment for forming a film on the surface of the workpiece. A method for producing a powder molded body electrode, comprising a conductive organic material comprising a material having a π-conjugated bond in the main chain on at least one of powder particles of metal powder, metal compound powder, glass powder and ceramic powder Mixing the powder to produce a mixed powder, pressurizing the mixed powder to cause the conductive organic material powder to enter between the powder particles, and filling the conductive organic material between the powder particles And a step of forming into a pressurizing form having a specific resistance of 10 ⁴ Ω · cm or less .

  The present invention uses a conductive organic material as a binder component of a conductive powder molded body electrode. Therefore, in order to reduce the resistance of the electrode, the object is to degrease in a high temperature / vacuum and sinter the material to be a film. The electrical resistance of the electrode can be lowered without performing the heat treatment, and the pulsed discharge in the discharge surface treatment in the machining liquid is concentrated on the conductive organic material, so that the conductive organic material is instantly decomposed and Since it evaporates, the material forming the coating is not limited to carbides, and there is a remarkable effect that unnecessary materials are not mixed into the coating.

Embodiment 1 FIG.
FIG. 1 is a schematic diagram showing an enlarged cross-sectional internal structure of a conductive powder molded body electrode according to Embodiment 1 for carrying out the present invention. In FIG. 1, a conductive powder molded body electrode 1 according to the present embodiment is filled with a conductive organic material 3 so as to surround powder particles 2 that are materials of a film formed on a workpiece by discharge surface treatment. It is pressure-molded.

A method for producing a conductive powder molded body electrode in the present embodiment will be described. FIG. 2 is a schematic view showing a part of a production apparatus for producing a conductive powder molded body electrode in the present embodiment. In FIG. 2, the die 5 fixed on the die plate 4 has, for example, a cylindrical space that matches the shape of the conductive powder molded body electrode at the center. A powder of SUS304 (see Table 1 for the composition) having a particle size of 1 to 20 μm and a specific resistance of about 7 × 10 ⁻⁵ Ω · cm is added to a powder of 0.1 to 5 μm and a specific resistance of about 3 × 10 ^−4. An Ω · cm polypyrrole powder was mixed at a ratio of about 10 wt% with respect to the weight of the SUS304 powder, and the mixed powder 6 was filled in the cylindrical space of the die 5. The mixed powder 6 was press-molded by applying a pressure of 100 to 500 MPa to the mixed powder 6 with a press punch 7 fitted into the cylindrical space of the die 5. The pressure-molded mixed powder 6 was taken out of the die plate 4, the die 5 and the press punch 7 to obtain the conductive powder molded body electrode 1 of the present embodiment.

  Since the conductive polypyrrole powder has plasticity, when the mixed powder 6 is pressure-molded, it enters between the particles of the SUS304 powder particles 2 as a coating material as shown in FIG. The composition is deformed in accordance with the shape in between, and the conductive organic material 3 is filled.

FIG. 3 is a characteristic diagram showing the relationship between the molding pressure of the conductive powder molded body electrode 1 and the conductivity which is the reciprocal of the specific resistance in the present embodiment. In FIG. 3, the conductivity and molding pressure when the molding pressure is increased and the conductivity is saturated are defined as 100%. From the viewpoint of strength for maintaining the shape of the conductive powder molded body electrode 1, the optimum range of the relative molding pressure is preferably 10 to 80%. When the relative molding pressure is less than 10%, the strength of the conductive powder molded body electrode 1 becomes insufficient, and the conductive powder molded body electrode 1 may be damaged or broken when attached to the discharge surface treatment apparatus. On the other hand, when the relative molding pressure is greater than 80%, the adhesion strength between the pressure-formed mixed powder 6 and the die plate 4 or 5 increases, and the pressure-formed mixed powder 6 is used as the die plate 4 and die 5. In addition, there is a risk of damage or breakage when taking out from the press punch 7. Even if the relative molding pressure when forming the conductive powder molded body electrode 1 is in an appropriate range, if the specific resistance of the conductive powder molded body electrode 1 exceeds 10 ⁴ Ω · cm, the discharge surface When used as an electrode of a processing apparatus, the discharge in the machining fluid becomes unstable, and a film having no defect cannot be formed.

  The conductive powder molded body electrode 1 configured as described above is in a state in which the conductive organic material 3 is filled between the particles of the powder particles 2 of SUS304, which is the material of the coating, and the conductive organic material 3 Has sufficient bonding strength for bonding the powder particles 2 and conductivity for reducing the contact resistance with the powder particles, so that the necessary strength and electric resistance when used as an electrode of a discharge surface treatment apparatus are obtained. It has.

  When the conductive powder molded body electrode obtained in the present embodiment is used as an electrode of a discharge surface treatment apparatus, when discharge occurs in the processing liquid, the conductive organic material contained in the conductive powder molded body electrode is Since it is instantly decomposed into hydrocarbons and melted in the working fluid, unnecessary materials do not enter the coating when the coating is formed, and the coating material can become carbide by the discharge energy. The material is not limited. Furthermore, there is no need to perform heat treatment for degreasing and sintering in high temperature and vacuum, which is necessary when mixing an insulator such as an epoxy adhesive.

  In addition, since the resistance value of the conductive powder molded body electrode can be adjusted with a conductive organic material, a conductive metal that is not necessary as a coating material as in the prior art, but is necessary for adjusting the resistance value. Without addition, the resistance value of the conductive powder molded body electrode can be adjusted to the conditions of the discharge surface treatment.

  Furthermore, in addition to the conductive organic material, other organic binders can be used in combination in order to improve the moldability, so that it is possible to produce a conductive powder molded body electrode having a complicated shape.

Embodiment 2. FIG.
In Embodiment 2, the conductive powder molded body electrode obtained by the same composition and manufacturing method as in Embodiment 1 is compared with the molded body electrode obtained by the conventional manufacturing method.

In the present embodiment, a conductive powder molded body electrode obtained by the same method as in the first embodiment will be described. An SUS304 powder having an average particle size of 1 μm and a specific resistance of about 7 × 10 ⁻⁵ Ω · cm is added to a SUS304 powder having an average particle size of 0.5 μm and a specific resistance of about 3 × 10 ⁻⁴ Ω · cm. Is mixed at a ratio of about 10 wt% with respect to the weight of the powder, and is pressure-molded by applying a pressure of 200 to 300 MPa with the same apparatus as in the first embodiment to obtain the conductive powder molded body electrode of the present invention. It was. The specific resistance of the obtained conductive powder molded body electrode was about 5.5 × 10 ⁻³ Ω · cm.

Next, a molded body electrode produced by a conventional production method will be described for comparison. An organic binder obtained by adding several percent of stearic acid to a mixture of paraffin and polyethylene heated and melted at 150 to 200 ° C., and a powder of SUS304 having an average particle diameter of 1 μm and a specific resistance of about 7 × 10 ⁻⁵ Ω · cm Were mixed at a volume ratio of 1: 1, and the mixture was sufficiently kneaded, and then pressure-molded by applying a pressure of 50 to 200 MPa. The pressure-molded product was vacuum degreased at 300 to 500 ° C., and then fired at about 1000 ° C. using a vacuum furnace to obtain a molded electrode produced by a conventional manufacturing method.

  A film is formed on the surface of an Fe-based alloy workpiece that has been mirror-polished by a discharge surface treatment apparatus using the conductive powder molded body electrode of the present embodiment and the molded body electrode obtained by a conventional manufacturing method. The Vickers strength of the coating was measured. The film thickness of the coating is about 10 μm. Both the strength of the film formed with the conductive powder molded body electrode of the present embodiment and the Vickers hardness of the film formed with the molded body electrode obtained by the conventional manufacturing method are 1300 to 1320 Hv, and the adhesive strength is also strong. There was no difference between the two in terms of corrosion resistance to acids and alkalis.

  As described above, the film formed with the conductive powder molded body electrode according to the present embodiment has the same characteristics as the film formed with the molded body electrode produced by the conventional manufacturing method. When an organic material is used, an electrode for discharge surface treatment having the same performance as the conventional one can be obtained without performing the heat treatment in the conventional high temperature and vacuum.

  In this embodiment, an Fe-based alloy is used as a workpiece. However, the present invention is not limited to this, and pure metals or alloys such as Co-based, Ni-based, Al-based, and Cu-based materials can also be used.

Embodiment 3 FIG.
In Embodiment 3, when forming a conductive powder molded body electrode by the same method as in Embodiment 1, a conductive powder molded body electrode was manufactured by variously combining a material to be a film and a conductive organic material. Is.

  Table 1 shows the relationship between the powder name and the composition of the material to be the coating in the present embodiment. Table 2 classifies the names of the conductive organic materials in the present embodiment.

In this embodiment, the powder selected from the powder names shown in Table 1 is mixed with the conductive organic material powder selected from the π-conjugated bond conductive organic material powder shown in Table 2. A conductive powder molded body electrode was produced in the same manner as in Embodiment 1. If the specific resistance of the produced conductive powder molded body electrode is less than or equal to the order of 10 ⁴ Ω · cm, the original characteristics of the powder material selected from Table 1 when used as an electrode for a discharge surface treatment apparatus ( It was found that a film having characteristics equivalent to corrosion resistance, abrasion resistance, impact resistance, etc. can be formed. However, when the proportion of the conductive organic material increases in order to make the specific resistance less than the order of 10 ⁴ Ω · cm, the deposition rate of the coating decreases according to the increase proportion, and the surface roughness of the deposited coating also increases. To increase. The reason for such a decrease in the deposition rate is considered to be based on a decrease in the use efficiency of the discharge energy due to an increase in the component outside the film formation (conductive organic material) of the conductive powder compact electrode. In addition, the increase in the surface roughness of the deposited film is caused by the large amount of gas generated by the decomposition of the conductive organic material by the discharge energy, which is mixed in the processing liquid, and this gas is the dissociation gas of the processing oil that becomes the discharge path of the main discharge. Unbalanced coating formation based on the fact that unstable discharge is induced to affect the surface of the electrode and that the surface of the conductive powder molded body electrode has conspicuous unevenness and the spark discharge is concentrated between the shortest electrodes. Is considered to be the cause. Such an unstable discharge is caused by the sputtering of the electrode based on the collision of the ionizing gas (plus ions) of the working fluid reaching the surface of the conductive powder compact electrode when the polarity of the conductive powder compact electrode is negative. It is considered that the decomposition gas of the conductive organic material resulting from the temperature rise due to the collision energy affects the ionization process of the machining fluid generated by the main discharge. This means that when the discharge peak current is reduced to 5 to 10%, usually at 10 to 20 A, and the discharge pulse width is reduced to 5 to 10%, usually at 20 to 100 μs, unstable discharge is caused. It was confirmed from experiments that the improvement was achieved by the quantitative effect of the decomposition gas of conductive organic materials (the effect of this on the ionization process) (reducing the above-mentioned discharge injection energy, reducing the thermal factors, and generating decomposition gas. The effect when the amount is suppressed can be inferred.

  In this embodiment, one material selected from the conductive organic materials shown in Table 2 was mixed with the material for forming the film when the conductive powder molded body electrode was produced. Two or more conductive organic materials may be selected and used.

Embodiment 4 FIG.
In the first embodiment, the conductive powder molded body electrode was produced by using a normal pressure molding method. However, in the fourth embodiment, in order to mass-produce the conductive powder molded body electrode having the same shape, extrusion was performed. The molding method is used.

A method for producing a conductive powder molded body electrode in the present embodiment will be described. A quartz glass powder having an average particle diameter of 2 μm, a conductive organic material powder in which a pyrrole oligomer treated with a dopant and polyacetylene are mixed at a weight ratio of 20:80 and tetrahydrofuran (THF) as a solvent are mixed at a weight ratio of 80 : 3:17 mixed. Further, 0.3 wt% of a dispersant was added to the mixture, mixed, and charged into an extrusion molding machine. The charged mixture was sufficiently kneaded by a screw-type kneader in the extruder, and after THF was removed in a vacuum chamber, the mixture was extruded at 20 MPa with an auger blade to obtain a conductive powder molded body electrode. The specific resistance of the obtained conductive powder molded body electrode was 1.0 to 2.0 × 10 ⁻² Ω · cm, and the internal structure was the same as that shown in FIG.

  The conductive powder molded body electrode thus produced was used as an electrode of a discharge surface treatment apparatus to form a film on the surface of a mirror-finished workpiece made of Mo. Discharge surface treatment was performed using a conductive powder molded body electrode as a negative electrode under conditions of a peak current of 5 A or less and a pulse width of 20 μs or less. As a result, an average surface roughness of the film was 1 μm, and a quartz film with sufficient adhesion and corrosion resistance. Could be formed. Further, when elemental analysis of this film was performed, contamination of impurities due to organic substances such as carbon was not detected.

  In this embodiment, it is possible to form an insulating film, which has been difficult to produce by conventional discharge surface treatment, and the application range of the material to be a film used for the conductive powder molded body electrode is remarkably increased. It is an expanded one. In this embodiment, the conductive organic material powder and the insulating quartz glass powder to be a film are uniformly kneaded using a solvent and a dispersant, and the conductive powder produced by extrusion molding of this mixture. In the molded body electrode, the conductive organic material enters the insulating powder so as to surround the periphery of the insulating powder, thereby forming a very homogeneous conductive powder molded body. In particular, by mixing pyrrole oligomers with high plasticity into polyacetylene with relatively low plasticity, the specific resistance of the obtained conductive powder molded body electrode can be reduced, and the molding pressure of extrusion molding can be increased more than necessary. In addition, since the conductive powder molded body electrode having the required strength can be produced, there is an effect that the yield of the conductive powder molded body electrode is improved.

In this embodiment, an example in which quartz glass powder is used as a material for a coating film is shown. However, if the average particle size is 20 μm or less, insulating powder such as normal glass powder and ceramic powder is used. You can also. In this case, if the specific resistance of the conductive powder molded body electrode produced in combination with the conductive organic material is less than or equal to the order of 10 ⁴ Ω · cm, a uniform film is formed when used as an electrode for discharge surface treatment. be able to.

  In this embodiment mode, an example in which a pyrrole oligomer is used as the conductive organic material has been described. However, a monomer including a solvent, a polymerization agent, and a dopant agent may be used. In this case, the material powder to be coated and this monomer are mixed, and the conductive organic material is gelled in the kneading process in the extrusion molding machine. After removing the solvent in the vacuum chamber, extrusion molding is performed to form a conductive powder molded body electrode. Can be obtained. This method has operational advantages such as easy viscosity adjustment in the kneading process.

  Further, in the present embodiment, the mirror-polished Mo workpiece is used, but the present invention is not limited to this, and pure metals such as Fe-based, Co-based, Ni-based, Al-based, and Cu-based materials are used. Alternatively, an alloy can be used.

Embodiment 5 FIG.
In the fourth embodiment, an example of the manufacturing method by the extrusion molding method for the purpose of mass-producing conductive powder molded body electrodes having the same shape has been shown. However, in the fifth embodiment, a more complicated shape is used. This is an injection molding method capable of mass-producing a conductive powder molded body electrode.

A method for producing a conductive powder molded body electrode in the present embodiment will be described. Conductive organic material in which alumina powder having an average particle size of 5 μm, P-phenylene vinylene monomer containing a polymerization initiator and a dopant, and polythiophene having a specific resistance of 3 × 10 ⁻³ Ω · cm are mixed at a weight ratio of 70:30. The material powder and THF as a solvent were mixed at a weight ratio of 80: 3: 17. Further, 0.25 wt% of a dispersant was added to this mixture and sufficiently kneaded with a screw kneader. The obtained kneaded material was conveyed into a vacuum chamber to remove the solvent, and then kneaded again with a screw kneader while heating at a temperature lower than the polymerization temperature of the polymerization initiator. The kneaded product is pressed into a mold kept at the polymerization temperature at an injection pressure of 50 to 200 MPa to form a molded body, and the kneaded product is polymerized in a state where a holding pressure of 20 to 60 MPa is applied to the molded body. The molded body was completely solidified. Finally, after the completely solidified molded body was cooled to room temperature, the inside of the mold was opened to atmospheric pressure, and the molded body was taken out of the mold to obtain a conductive powder molded body electrode. The specific resistance of the obtained conductive powder molded body electrode was 6.3 to 6.8 × 10 ⁻² Ω · cm, and the internal structure was the same as that shown in FIG.

  The conductive powder molded body electrode thus produced was used as an electrode of a discharge surface treatment apparatus to form a coating on the surface of a mirror-finished workpiece made of Al. Discharge surface treatment was performed using a conductive powder molded body electrode as a negative electrode under conditions of a peak current of 7 A or less and a pulse width of 20 μs or less. The average surface roughness of the coating was 1.2 μm, and the alumina had sufficient adhesion and corrosion resistance. It was possible to form a coating. Further, when elemental analysis of this film was performed, contamination of impurities due to organic substances such as carbon was not detected.

  In the present embodiment, as in the fourth embodiment, it is possible to form a coating of an insulator that has been difficult to produce by conventional discharge surface treatment, and a coating used for a conductive powder molded body electrode. This greatly expands the range of application of the material. In addition, since the conductive powder molded body electrode can be formed by an injection molding method, there is an effect that a conductive powder molded body electrode having a complicated shape can be formed. Furthermore, since the P-phenylene vinylene monomer used in the present embodiment exhibits liquidity or plasticity before polymerization, the kneaded product has high fluidity during kneading and becomes electrically conductive after polymerization, so that it becomes a molded product. In addition, conductivity is imparted when it is polymerized and completely solidified with a holding pressure applied. As a result, injection molding is facilitated, and there is an effect that a conductive powder molded body electrode having high strength and low specific resistance can be obtained.

Furthermore, when measuring the bending strength of the conductive powder molded body electrode obtained in the present embodiment,
A bending strength of 5 to 10 times or more that of a conventional electrode formed only with a conductive organic material powder was exhibited, and a conductive powder molded body having a very uniform and low specific resistance could be obtained. The bending strength indicates the bending strength of the material. The maximum fracture when a plate-shaped specimen is supported by two fulcrums and a load is applied to the upper center of the specimen between the fulcrums. It is a load per unit cross-sectional area (Kg / cm ² ) due to the load. In addition, by confirming the possibility of compression molding of electrodes by injection molding, it has the effect of expanding the freedom of material selection and at the same time enabling high-precision mass production of insulators with complex shapes as electrodes. is there.

In this embodiment, an example in which alumina powder is used as a material for the coating film is shown. However, if the average particle size is 20 μm or less, insulating powder such as normal glass powder or ceramic powder should be used. You can also. In this case, if the specific resistance of the conductive powder molded body electrode produced in combination with the conductive organic material is less than or equal to the order of 10 ⁴ Ω · cm, a uniform film is formed when used as an electrode for discharge surface treatment. be able to.

In the present embodiment, P-phenylene vinylene monomer and polythiophene are used as the conductive organic material. Table 2 shows a material that includes a dopant and a polymerization initiator and exhibits conductivity after polymerization. Monomers, oligomers, conductive polymer materials, and the like can be mixed and used at a mixing ratio suitable for injection molding. Also in this case, the specific resistance of the conductive powder molded body electrode produced by combining the conductive organic material and the powder material to be the film may be less than or equal to the order of 10 ⁴ Ω · cm.

  According to this method, after press-fitting the kneaded material into a mold, a monomer and an oligomer exhibiting high conductivity after polymerization were polymerized while applying a holding pressure, so that the conductive organic material efficiently covered the powder, and between the powder particles Therefore, the specific resistance is small and the strength of the electrode is increased.

In this embodiment, the conductive organic material powder is a mixture of a conductive polymer powder and a monomer or oligomer. However, as the conductive organic material, only the monomer or oligomer is mixed and kneaded with a material powder that forms a film. If the specific resistance is 10 ⁴ Ω · cm or less even after polymerization and solidification after press-fitting into the mold, a conductive powder molded electrode for submerged electric discharge machining equivalent to the electrode shown in the present embodiment Is obtained.

  Furthermore, in the present embodiment, a mirror-finished workpiece made of Al is used, but the present invention is not limited to this, and pure metals or alloys such as Fe, Co, Ni, and Cu are used. Alternatively, alloys such as Al—Mn, Al—Si, and Al—Mg can be used.

Embodiment 6 FIG.
Embodiment 6 aims to obtain a conductive powder molded body electrode with further improved formability by combining a highly plastic conductive organic material powder and a low plastic conductive organic material powder. is there.

A method for producing a conductive powder molded body electrode in the present embodiment will be described. Pure Al powder with an average particle size of 1.0 μm and specific resistance of 2.6 × 10 ⁻⁶ Ω · cm, high plasticity polyaniline with specific resistance of 3 × 10 ⁻³ Ω · cm and low plasticity (the plasticity is somewhat improved) A conductive organic material mixed with polyacetylene having a specific resistance of 5 × 10 ⁻⁴ Ω · cm at a weight ratio of 30:70 and N-methyl-2-pyrrolidone (NMP) as a solvent in a weight ratio of 80 : Mixed at a ratio of 8:12. Using this mixture, a conductive powder molded body electrode was produced by the same pressure molding method as in the first embodiment. The pressure at the time of pressure molding is 100 to 200 MPa. For comparison, a conductive powder molded body electrode using only polyaniline as an organic conductive material and a conductive powder molded body electrode using only polyacetylene were simultaneously produced.

  Table 3 shows the relationship between the material of the produced conductive powder molded body electrode, the specific resistance, and the bending strength. Electrode A is a conductive powder molded body electrode produced by combining a highly plastic conductive organic material powder and a low plastic conductive organic material powder. Electrode B and electrode C are each a highly plastic conductive organic material. This is a conductive powder molded body electrode made only of a material powder and a conductive organic material powder having low plasticity.

  From Table 3, the electrode A produced by combining the highly plastic conductive organic material powder and the low plastic conductive organic material powder is more resistant to bending than the electrode B produced only from the highly plastic conductive organic material powder. Although the strength is inferior, the specific resistance is low, and the bending strength is higher than that of the electrode C made of only the conductive organic material powder having low plasticity.

  Further, as shown in Table 3, the specific resistance of the conductive powder molded body electrode was improved as compared with the electrode C to which t-PA having a small specific resistance was added. This is because the conductive organic material enters between the Al particles and is firmly bonded while covering the Al particles in the process of removing the solvent, and when an external force is applied, the soft / hard organic material and the inorganic material powder interact with each other. It is thought that the shape is maintained by the buffer effect and the electrostatic effect. For this reason, the conductivity in which the side chain of the monomer is replaced with an alkyl group having excellent flexibility (to the extent that conductivity is deteriorated when the planarity of the molecular chain is lost, so that conductivity is not extremely sacrificed) If a conductive powder molded body electrode is produced using a conductive organic material, an effect of improving electrode strength and specific resistance can be expected.

  The electrode A thus produced was used as an electrode of a discharge surface treatment apparatus, and a coating film was formed on the surface of an Fe-based alloy workpiece that was mirror-polished. When the discharge surface treatment was performed with the electrode A as the negative electrode and a peak current of 4 A or less and a pulse width of 20 μs or less, the specific resistance of the film was almost the same as that of pure Al, and an Al film with sufficient adhesion and corrosion resistance was formed. We were able to.

  In the present embodiment, a mirror-finished workpiece of an Fe-based alloy is used. However, the present invention is not limited to this, and pure metals or alloys such as Co-based, Ni-based, Al-based, and Cu-based are used. Can also be used.

Embodiment 7 FIG.
In the seventh embodiment, the Al—Si alloy powder obtained by adding 12 wt% of Si to Al is used instead of pure Al as the material for forming the film in the sixth embodiment. The conductive organic material is a combination of a highly plastic conductive organic material powder and a low plastic conductive organic material powder.

A method for producing a conductive powder molded body electrode in the present embodiment will be described. Al-Si alloy powder having an average particle diameter of 1.5 μm and a specific resistance of 5.0 × 10 ⁻⁶ Ω · cm, a polyaniline having a high plastic resistivity of 3 × 10 ⁻³ Ω · cm and a low plastic resistivity Conductive organic material mixed with 5 × 10 ⁻⁴ Ω · cm polyacetylene at a weight ratio of 30:70 and N-methyl-2-pyrrolidone (NMP) as a solvent at a weight ratio of 80: 8: 12 Mixed. Using this mixture, a conductive powder molded body electrode was produced by the same pressure molding method as in the first embodiment. The pressure at the time of pressure molding is 100 to 200 MPa.

  The bending strength of the conductive powder molded body electrode thus produced showed a bending strength substantially equivalent to that of the electrode A of the sixth embodiment. Furthermore, using the conductive powder molded body electrode obtained in the present embodiment as an electrode of a discharge surface treatment apparatus, a coating was formed on the surface of a mirror-polished Fe-based alloy workpiece. Discharge surface treatment was performed under the conditions of a peak current of 4 A or less and a pulse width of 20 μs or less using a conductive powder molded body electrode as a negative electrode. A sufficient Al—Si alloy film could be formed.

Embodiment 8 FIG.
Embodiment 8 aims at obtaining a conductive powder molded body electrode with further improved formability by combining a highly plastic insulating organic binder powder and a low plastic conductive organic material powder. It is.

A method for producing a conductive powder molded body electrode in the present embodiment will be described. Pure Zn powder having an average particle diameter of 1.2 μm and a specific resistance of 6.0 × 10 ⁻⁶ Ω · cm and highly plastic insulating polyethylene are mixed at a weight ratio of 93: 7, and this mixture is mixed with argon gas. Kneading in an atmosphere while heating to 150 to 200 ° C. until sufficiently uniform. The kneaded product was cooled to room temperature and finely pulverized, and then t-PA (polyacetylene) having low plasticity and a specific resistance of 5.0 × 10 ⁻⁵ Ω · cm was 70 wt% relative to the weight of polyethylene in the kneaded product. %, And knead uniformly enough. Finally, pressure forming was performed in the same manner as in Embodiment 1 to form a conductive powder molded body electrode. The pressure at the time of pressure molding is 100 to 200 MPa.

FIG. 4 is an enlarged schematic view showing the internal cross-sectional structure of the conductive powder molded body electrode obtained in the present embodiment. In FIG. 4, the conductive powder molded body electrode 1 in the present embodiment includes polyethylene 9 so as to surround pure Zn particles 8 as a material of a film formed on the workpiece by the discharge surface treatment, The polyacetylene 10 is filled around and pressure-molded. The specific resistance of the conductive powder molded body electrode thus produced was 2.0 × 10 ⁻³ Ω · cm. Furthermore, when this conductive powder molded body electrode was used as an electrode of a discharge surface treatment apparatus and a film was formed on the surface of a mirror-finished Fe-based alloy workpiece, a film having a predetermined resistance value and corrosion resistance was obtained. Obtained.

  In this way, by combining a highly plastic insulating organic binder powder and a low plastic conductive organic material powder, the conductive organic material enters between the Zn particles, and the Zn particles are coated in the process of removing the solvent. The electrode strength and specific resistance can be maintained by pressing and molding, and maintaining the shape by the buffering effect and electrostatic effect between the highly plastic organic material, the low plastic organic material and the Zn powder. There is an effect to improve.

In the present embodiment, an example in which polyethylene is used as an insulating organic binder having high plasticity is shown, but high moldability can be obtained even with a paraffin or epoxy material. Moreover, although the example which uses pure Zn powder as a material used as a film was shown, other materials, for example, powders such as metals and alloys shown in Table 1 or glass or ceramics may be used. In this case, the specific resistance of the conductive powder molded electrode produced in combination with the conductive organic material may be no more than the order of 10 ⁴ Ω · cm. Further, as the conductive organic material, materials other than polyacetylene, for example, the materials shown in Table 2 can be used. In this case, the specific resistance of the produced conductive powder molded body electrode is 10 ⁴ Ω · cm. Any order or less is acceptable.

Embodiment 9 FIG.
In the ninth embodiment, similarly to the eighth embodiment, a conductive powder molded body electrode is formed by using an injection molding method by combining a highly plastic insulating organic binder powder and a low plastic conductive organic material powder. The purpose is to produce.

A method for producing a conductive powder molded body electrode in the present embodiment will be described. A Ni—Cu alloy powder (Cu: 30 wt%) having an average particle diameter of 1.0 μm and a specific resistance of 3.4 × 10 ⁻⁵ Ω · cm, highly plastic insulating polyethylene and conductive polyacetylene in a weight ratio of 75: The mixture is mixed at a ratio of 15:10, and the mixture is kneaded in a nitrogen gas atmosphere while being heated to 150 to 200 ° C. until sufficiently uniform. The kneaded product was press-fitted into the mold at a pressure of about 200 MPa by a screw injector, and then cooled to room temperature with a holding pressure of about 50 MPa to obtain a conductive powder molded body electrode.

The specific resistance of the conductive powder molded body electrode thus produced was 7.0 × 10 ⁻² Ω · cm. Furthermore, when this conductive powder molded body electrode was used as an electrode of a discharge surface treatment apparatus and a film was formed on the surface of a mirror-finished Fe-based alloy workpiece, Ni- having a predetermined resistance value and corrosion resistance A Cu alloy coating was obtained.

  In the present embodiment, conductive polyacetylene and insulating polyethylene are mixed and used as the conductive organic material, and further, kneading is performed at 150 to 200 ° C. at which polyethylene is melted. It is possible to maintain high yield and shape accuracy during injection molding.

In the present embodiment, an example in which polyethylene is used as an insulating organic binder having high plasticity is shown, but high moldability can be obtained even with a paraffin or epoxy material. Moreover, although the example which uses Ni-Cu alloy powder as a material used as a film was shown, other materials, for example, powders such as metals and alloys shown in Table 1 or glass or ceramics may be used. In this case, the specific resistance of the conductive powder molded electrode produced in combination with the conductive organic material may be no more than the order of 10 ⁴ Ω · cm. Further, as the conductive organic material, materials other than polyacetylene, for example, the materials shown in Table 2 can be used. In this case, the specific resistance of the produced conductive powder molded body electrode is 10 ⁴ Ω · cm. Any order or less is acceptable.

Embodiment 10 FIG.
The tenth embodiment aims to further improve the strength by using a polymerization initiator and a monomer when an electroconductive powder molded body electrode is produced using an injection molding method.

A method for producing a conductive powder molded body electrode in the present embodiment will be described. The SKH51 alloy powder having an average particle diameter of 1.0 μm and a dopant-treated thiophene monomer containing a polymerization initiator were mixed at a weight ratio of 85:15. Further, 0.25 wt% of a dispersant is added to this mixture, and the mixture is put into a screw kneader and kneaded while being heated at a temperature lower than the polymerization temperature of the polymerization initiator. The kneaded product is pressed into a mold kept at the polymerization temperature at an injection pressure of 50 to 200 MPa to form a molded body, and the kneaded product is polymerized in a state where a holding pressure of 20 to 60 MPa is applied to the molded body. The molded body is completely solidified. Finally, after the completely solidified molded body was cooled to room temperature, the inside of the mold was opened to atmospheric pressure, and the molded body was taken out of the mold to obtain a conductive powder molded body electrode. The specific resistance of the obtained conductive powder molded body electrode was 4.5 × 10 ⁻³ Ω · cm.

  The conductive powder molded body electrode thus produced was used as an electrode of a discharge surface treatment apparatus to form a film on the surface of a mirror-finished workpiece made of Fe. Discharge surface treatment was performed using a conductive powder molded body electrode as a negative electrode under conditions of a peak current of 8 A or less and a pulse width of 20 μs or less. As a result, SKH51 having an average surface roughness of 0.9 μm and a Vickers strength of 1600 to 1650 Hv. An alloy coating could be formed. Further, when elemental analysis of this film was performed, contamination of impurities due to organic substances such as carbon was not detected.

  In the present embodiment, since a monomer containing a polymerization initiator is used for the conductive organic material, the electrode strength is improved by polymerizing at the time of pressure molding and sufficiently adhering the powder particles, and the ratio The resistance is also reduced.

In the present embodiment, an example in which the SKH51 alloy powder is used as the material for the coating film is shown. However, other materials, for example, metals and alloys shown in Table 1, or powders of glass or ceramics may be used. . In this case, the specific resistance of the conductive powder molded electrode produced in combination with the conductive organic material may be no more than the order of 10 ⁴ Ω · cm. Further, as the conductive organic material, materials other than polyacetylene, for example, the materials shown in Table 2 can be used. In this case, the specific resistance of the produced conductive powder molded body electrode is 10 ⁴ Ω · cm. Any order or less is acceptable.

It is a schematic diagram which shows the internal cross-section of the electroconductive powder molded object electrode by Embodiment 1 of this invention. It is a schematic diagram which shows a part of manufacturing apparatus in Embodiment 1 of this invention. It is a characteristic view of the electroconductive powder molded object electrode by Embodiment 1 of this invention. It is a schematic diagram which shows the internal cross-section of the electroconductive powder molded object electrode by Embodiment 8 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electroconductive powder molded body electrode 2 Powder particle 3 Conductive organic material 4 Die plate 5 Die 6 Mixed powder 7 Press punch 8 Pure Zn particle 9 Polyethylene 10 Polyacetylene

Claims (5)

A conductive powder molded body electrode used for discharge surface treatment for generating a pulsed discharge between a workpiece and forming a film on the surface of the workpiece,
The material to be coated is at least one of metal powder, metal compound powder, glass powder and ceramic powder;
The material to be coated is dispersed in a conductive organic material having a π-conjugated bond in the main chain to form a pressure molded body,
A conductive powder molded body electrode, wherein the pressure molded body has a specific resistance of 10 ⁴ Ω · cm or less. Conductive organic materials, acene-based compounds, pyrrole-based compounds, thiophene-based compounds, aniline-based compounds, conductive according to claim 1, wherein the at least one material of p- phenylene compounds and acetylene compounds Powder molded body electrode. 2. The conductive powder molding according to claim 1 , wherein the conductive organic material is at least one material of polyacene, polypyrrole, polythiophene, polyaniline, poly-p-phenylene, poly-p-phenylene vinylene and polyacetylene. Body electrode. The conductive powder molded body electrode according to claim 1 , wherein an insulating organic binder is present so as to surround the material to be coated , and the conductive organic material is filled therearound. A method for producing a conductive powder molded body electrode used for discharge surface treatment for generating a pulsed discharge between a workpiece and forming a coating on the surface of the workpiece,
A step of mixing a conductive organic material powder made of a material having a π-conjugated bond in the main chain with a powder particle of at least one of metal powder, metal compound powder, glass powder, and ceramic powder to produce a mixed powder When,
The mixed powder is pressurized to allow the conductive organic material powder to enter between the powder particles, and the conductive organic material is filled between the powder particles so that the specific resistance is 10 ⁴ Ω · cm or less. A process for producing a conductive powder molded body electrode comprising a step of molding into a shape .

Images