JP2615792B2 - Manufacturing method of acoustic diaphragm - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an acoustic diaphragm made of beryllium, boron, titanium, or the like. It can be manufactured easily and with good productivity by electroplating.

[Prior art] Generally, as an acoustic diaphragm, it is necessary to have high efficiency and good transient characteristics, and to extend the high frequency range, its mass is small, its Young's modulus is large, and its strength is high. Is required.

An acoustic diaphragm formed of an alloy containing beryllium, boron, titanium, or the like as a main component and a composite material has been known to substantially satisfy such requirements.

Conventionally, electron beam vacuum vapor deposition, powder metallurgy, hot press molding, and the like have been used to manufacture these acoustic diaphragms.

[Problems to be solved by the invention]

The electron beam vacuum vapor deposition method requires a large-scale apparatus, requires a long time for vapor deposition, and is expensive because the number of sets cannot be increased. Since powder metallurgy sinters in a high-temperature atmosphere, shrinkage during sintering cannot be avoided, and it is difficult to obtain an acoustic diaphragm having a uniform shape. Even in the hot press forming method, the processing steps for metals with poor workability such as beryllium, boron and titanium become very complicated, and those with large diameters and large tapered shapes cannot be processed. There were difficult points such as no.

For the above reasons, acoustic diaphragms made of metals such as beryllium, boron, and titanium have high performance but are inferior in productivity to general materials.

[Means for solving the problem]

In the present invention, beryllium, boron, or titanium is formed on a conductive substrate corresponding to the shape of the acoustic diaphragm by room-temperature plating in a molten salt comprising a halide of these metals and an alkylpyridinium halide. The solution is to form an acoustic diaphragm by electrodeposition.

[Action]

By using the above molten salt bath, even a metal having a strong oxygen affinity, which has conventionally been difficult to deposit at room temperature, can be easily treated, and a high-performance acoustic diaphragm can be manufactured very easily.

〔Example〕

 Hereinafter, the present invention will be described in detail.

FIG. 1 shows an example of an electroplating apparatus used in the manufacturing method of the present invention.

In the figure, reference numeral 1 denotes a plating tank (hereinafter, simply referred to as a tank). The vessel 1 is provided with a lid 2, and the lid 2 is provided with a gas introduction pipe 3 and a gas outlet pipe 4, so that the atmosphere in the vessel can be made an inert atmosphere. Also,
A plurality of sub wirings 6 are branched from the wiring in the cover 2, and a plurality of sub wirings 6 are branched from the wiring, and a base material 7 serving as a cathode is connected to the tip of the sub wiring 6. Is immersed in. On the other hand, a metal bar 9 for an acoustic diaphragm serving as an anode is provided soaked in a plating bath 8 near the bottom of the tank 1, and a stirrer 10 is provided on the side of the tank 1. Also,
The anode and the cathode are connected to a plating power supply 11.

The plating bath used in the present invention is a molten salt comprising a metal halide for an acoustic diaphragm and an alkylpyridinium halide. Beryllium, BeCl ₂ -C ₅ H ₅ N
-RX (R is an alkyl group having 1 to 5 carbon atoms, X is a halogen) molten salt and the like, in the case of boron, BCl ₃ -C ₅ H ₅ N-RX molten salt and the like, in the case of titanium in is a _{TiCl 3 -C 5 H 5 N-} RX molten salt. The halogen group may be fluorine or the like.
In any case, an alkylpyridinium halide, for example, butylpyridinium chloride, is added for the purpose of electrolysis of a room temperature molten salt. At this time, an aromatic organic solvent such as toluene, xylene, benzene or the like may be used alone or in a mixture of 20 to 80 to improve plating quality.
It is also effective to add vol%.

Regarding the concentration of the metal halide in the plating bath, the mixing molar ratio of the metal halide to the alkylpyridinium halide is preferably 3: 7 to 9: 1 in any case.

Adjustment of the plating bath is performed by appropriately melting the metal halide for the acoustic diaphragm at the electrolysis temperature in the purified molten support bath,
adjust.

Conventionally, the plating bath temperature is generally around 1000 ° C. for beryllium and boron, and 600 to 8 for titanium.
When the temperature is in the range of 00 ° C., but butylpyridinium chloride or the like is added, the temperature is from room temperature to 200 ° C. In order to improve plating efficiency, it is effective to stir by a stirrer such as a stirrer or an ultrasonic device.

The electrolysis current, such as direct or pulsed current can be used, but the range of 0.1 to 10 A / dm ² as the current density are mainly used, and preferably from 2 to 5 A / dm ² about. The plating time depends on the plating film thickness and the like. It is possible to control the thickness of the plating layer by controlling the electrolytic current density, the conduction time, and the temperature. The plating tank needs to be maintained in an atmosphere of an inert gas such as argon or nitrogen in order to prevent the molten metal halide from being oxidized by oxygen in the air.

As described above, the plating is performed using the metal bar for the acoustic diaphragm as the anode and the substrate 7 as shown in FIGS. 2 and 3 as the cathode. The anode may be insoluble or soluble.

FIG. 2 shows an example in which the cathode substrate is removed after plating.

In the figure, reference numeral 12 denotes a cathode base material to be plated, which is removed by a process such as etching, so that copper or the like, which is an inexpensive and high electric conductivity material, is formed into a dome shape by pressing or the like. , The inside of the dome is a masking layer 13
Is masked to prevent plating. Generally, polyethylene or the like is used as a mask material. Cathode substrate 12 masked by masking layer 13
Is immersed in a molten salt bath and plated. After plating is completed, the masking layer 13 is washed and removed with an organic solvent such as toluene or freon, and the cathode substrate 7 is removed with an oxidizing acid such as concentrated nitric acid to obtain a desired dome-shaped acoustic diaphragm.

FIG. 3 shows an example in which the cathode substrate is not removed after plating. In the figure, 14 is a cathode substrate, which is not removed after plating, so that a lightweight and flexible electric conductor is used, and a metal thin film such as copper may be used for this. Alternatively, a plastic film whose surface has been subjected to a conductive treatment by applying tin oxide or the like, a composite material obtained by impregnating paper or nonwoven fabric with carbon fiber or the like to have conductivity, or the like may be used. This kind of cathode substrate can be used as it is as a dome-shaped acoustic diaphragm after plating.

Regardless of whether or not the cathode base material is removed after plating, it is desirable to perform a treatment such as cermet formation after the formation of the acoustic diaphragm in order to prevent the surface from being oxidized and deteriorated.

According to the manufacturing method of the acoustic diaphragm as described above, the production of the acoustic diaphragm which has been expensive and complicated until now is inexpensive and simple, and at this time, the current density, the energizing time, and the temperature of the plating bath are controlled. As a result, a required film thickness can be obtained uniformly, and an arbitrary shape can be obtained freely without generation of pinholes, etc., and a high-quality acoustic diaphragm can be easily manufactured by a method rich in productivity. it can.

〔Example〕

(Example 1) Beryllium chloride as metal halide for acoustic diaphragm and butylpyridinium chloride (BPC) as additive
And a benzene / toluene mixed solvent were prepared.

These materials were mixed in a nitrogen atmosphere glove box so that the mixing molar ratio of beryllium chloride and BPC became 2: 1, and a mixed solvent of benzene / toluene was added at 30% to form a plating bath. A closed type electrolytic vessel was used, and the inside of the bath and the vessel space were replaced with deoxygenated dry nitrogen.

Beryllium ingot with a purity of 99% or more was used for the anode, and the cathode was press-molded in the form of an acoustic vibrating plate to a thickness of 0.2 mm, and a masking layer was formed on one side of the cathode substrate as shown in Fig. 2 at 13 Using an insulator coated to a thickness of 0.1 mm or more, electrolysis was performed with a direct current at a bath temperature of 25 ° C., a current of 5 A / dm ² , and a current amount of 40,000 C / dm ² .

The plating film obtained on the cathode substrate was smooth with a metallic luster, had a thickness of about 100 μm, and was 99% pure beryllium.

After dissolving and removing the insulator of the masking layer on the plated cathode substrate with an organic solvent, the copper substrate was further washed and removed with concentrated nitric acid to obtain a beryllium acoustic diaphragm.

(Experimental example 2) Plating was performed in the same manner as in Experimental example 1 except that a polyethylene resin was injection-molded into an acoustic vibrating plate to a thickness of 2 mm, and the surface was subjected to a conductive treatment using tin oxide to form a cathode substrate. Was done.

The thickness of the obtained plating film was 100 μm, and it was beryllium with a metallic luster and a smooth purity of 99% or more. The plated cathode substrate was washed and dried, and then used as it was as an acoustic diaphragm.

〔The invention's effect〕

As described above, in the method for manufacturing an acoustic diaphragm of the present invention, a conductive substrate is formed corresponding to the shape of the acoustic diaphragm, and beryllium, boron, or titanium is formed on the substrate. The metal for an acoustic diaphragm is electrodeposited by room temperature plating in a molten salt containing a halide of the metal for an acoustic diaphragm and an alkylpyridinium halide to form an acoustic diaphragm. Accordingly, a metal having a strong oxygen affinity, which has conventionally been difficult to deposit at room temperature, can be easily treated, and a high-performance acoustic diaphragm can be manufactured extremely easily. As described above, if any of beryllium, boron, and titanium is used as the metal for the acoustic diaphragm, a high-performance acoustic diaphragm can be realized.

Furthermore, molding of an arbitrary shape and control of the film thickness can be easily and accurately performed, and this is a very industrially and economically excellent production method.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an example of a plating apparatus used in carrying out the present invention, and FIGS. 2 and 3 are sectional views showing examples of a cathode base material used in the present invention. 1 ... Plating tank, 7 ... Cathode substrate, 8 ... Plating bath, 9
…… Anode, 11… Power supply, 12… Cathode substrate, 13… Cathode substrate.

Claims (1)

(57) [Claims] 1. A conductive base material is formed in accordance with the shape of an acoustic diaphragm, and a metal for an acoustic diaphragm, which is one of beryllium, boron, and titanium, is formed on the base material. A method for manufacturing an acoustic diaphragm, comprising forming an acoustic diaphragm by electrodeposition in a molten salt containing a metal halide and an alkylpyridinium halide by room-temperature plating.