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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,
which is easily and easily produced by cold temperature electroplating from molten salt of
beryllium, boron, titanium It is intended to be manufactured sexually. [Prior Art] Generally, as an
acoustic diaphragm, it is necessary to have high efficiency and good transient characteristics, and
in order to further extend a high range, its f (small ffi, large Young's modulus, strength thereof
Are required to be high. It is known that an acoustic diaphragm made of an alloy and a composite
material mainly composed of beryllium, bismuth, titanium and the like is generally satisfied as
such. Heretofore, electron beam vacuum deposition, powder metallurgy, hot brace forming, etc.
have been used to manufacture these acoustic diaphragms. [Problems to be Solved by the
Invention] In the electron beam vacuum deposition method, the apparatus is laborious, the time
required for the deposition is long, and the number of sets can not be increased, which is
expensive. In powder metallurgy, since sintering is performed in a high temperature atmosphere,
shrinkage during sintering can not be avoided, and it is difficult to obtain an acoustic diaphragm
having a uniform shape. Also in the hot-bore forming method, the processing process becomes
very complicated for metals with poor workability such as beryllium, boron, titanium etc., and
those with a large diameter and a large taber can be processed. There were problems such as no.
For the above reasons, acoustic diaphragms made of metals such as beryllium, boron and
titanium are inferior in productivity to i-general materials while having high performance.
[Means for Solving the Problems] In the present invention, any of beryllium, boron and titanium
is formed of a halide of these metals and an alkyl pyridinium halide on a conductive substrate
formed corresponding to the shape of the acoustic diaphragm. The solution is to form an acoustic
diaphragm by electrodeposition by cold plating in the molten salt. [Operation] The molten salt
bath makes it possible to easily process metals having high oxygen affinity, which have been
difficult to deposit by normal temperature plating, so that a performance acoustic perturbation
plate can be manufactured extremely easily. The present invention will be described in detail
below. 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. )である。 The tank 1 is provided with 'ri 2, and the lid
2 is provided with a gas introduction pipe 3 and a gas lead-out pipe 4 so that the atmosphere in
the tank can be made an inert atmosphere.
Further, a cathode wire 5 is provided in the lid 2, and a plurality of sub-wires 6 are branched
from this wire, and a base material 7 serving as a cathode is connected to a tip of the sub-wire 6
And is immersed in the plating bath 8. On the other hand, near the bottom of the tank 1, a bar 9
of a metal bending for acoustic vibration fJJ plate to be an anode is set and immersed in the bath
8 [the stirrer 10 is provided on the side of the tank 1] It is provided. The anode and the cathode
are connected to the plating power supply 11. The plating bath used in the present invention is a
molten salt composed of a metal halide for an acoustic diaphragm and an alkyl pyridinium halide.
In the case of beryllium, BeCl 2 -Cs Hs N -RX (R is an alkyl 1 to 5 carbon atoms, X is a halogen)
molten salt or the like, and the boron 1i (7) m compound GCGt, BClz -Cs 11 s N -RX It is a molten
salt etc., and in the case of titanium, it is TLCh-Cs H, N-RX molten salt etc. The halogen group
may be fluorine or the like. In any case, an alkyl pyridinium halide such as butyl pyridinium
chloride is added for the purpose of electrolysis at room temperature. At this time, for the
purpose of improving the quality of plating] ˜ Ruen. It is also effective to add 20 to 8 Qvo 1% of
an aromatic organic solvent such as xylene or benzene singly or in combination. In any case, the
mixing molar ratio of the metal halide and the alkyl pyridinium halide in the plating bath is
preferably 3 to 9: 1. The adjustment of the plating bath is carried out by appropriately melting
the metal halide for acoustic diaphragm etc. at the electrolysis temperature in the purified molten
support bath. Conventionally, the plating bath temperature is approximately 1000 ° C. in the
case of beryllium and bismuth, and in the range of 600 ° C. to 800 ° C. in the case of titanium,
but butyl pyridinium chloride or the like is added. In the case, it is normal temperature to 200 °
C. In order to improve the plating efficiency, it is effective to stir by a stirring means such as a
stirrer or an ultrasonic device. As the electrolytic current, direct current or pulse current can be
used. As the current density, a range of 0.1 to 1 oΔ / dm 2 is mainly used, and preferably about
2 to 5 A / d12. The plating time depends on the film thickness and the like. It is possible to
control the thickness of the plating layer by controlling these electrolytic current tightness,
current passing time, and temperature. The plating bath needs to be maintained in an
atmosphere of an inert gas such as argon, nitrogen and the like to prevent the molten metal
halide from being oxidized by oxygen in the air.
The plating is carried out using the base material 7 as shown in FIGS. 2 and 3 for the rod of the
metal for acoustic diaphragm and the cathode for the anode as described above. The anode may
be insoluble or soluble. FIG. 2 shows an example of removing the cathode substrate after plating.
In the figure, 12 is a cathode base material to be attached, and it is removed later by a process
such as etching, so it is formed by pressing an inexpensive material having a high electric
conductivity, such as # 4 into a dome shape. The inner side of the dome is masked by the
masking layer 13 so as not to be plated. In general, polyethylene or the like is used as the mask
material. The cathode substrate 12 masked by the masking layer 13 is dipped in a molten salt
bath and plated. The masking layer 13 is removed by washing with an organic solvent such as
toluene or freon in order to finish plating, the cathode substrate 7 is removed by oxidizing acid
such as concentrated nitric acid, and a target dome-shaped acoustic diaphragm is t9. FIG. 3
shows an example of the case where the cathode substrate is not removed after mounting. In the
figure, 14 is a cathode substrate, and since it is not removed after plating, a light and flexible
electric conductor is used, and a metal thin film such as copper may be used for this. In addition,
the surface of the plastic film has been electroconductively treated by coating with tin oxide, etc.,
carbon or paper or nonwoven fabric. It may be a composite material or the like in which a
conductive material is imparted by impregnating it with soot or the like. This type of cathode
substrate can be used as a dome shaped EI W / diaphragm as it is after plating. When the
cathode substrate is removed after plating or not removed, it is desirable to apply a treatment
such as cermetizing to prevent the surface from being oxidized and deteriorated after the
acoustic diaphragm is formed. According to the method of manufacturing the acoustic diaphragm
as described above, the manufacture of the expensive and complicated acoustic diaphragm
becomes inexpensive and easy, and further, at this time, control of the current density, the
conduction time, and the temperature of the plating bath The required film thickness can be
obtained uniformly, and any shape can be freely obtained without the occurrence of pinholes,
etc., and a high quality acoustic diaphragm can be manufactured easily and in a method that is
rich in productivity. it can. EXPERIMENTAL EXAMPLE (Experimental Example 1) Beryllium
chloride was prepared as a metal halide for an acoustic diaphragm, and butyl pyridinium chloride
(13PC) and a benzene / toluene mixed solvent were prepared as additives. These materials were
prepared in a nitrogen atmosphere glove box so that the molar ratio of beryllium chloride and
BPC was 2 = 1, and 30% of a benzene / toluene mixed solvent was added thereto to prepare a
plating bath.
The electrolytic vessel was a closed type, and the bath and the vessel space were replaced with
IIR oxygen dry nitrogen. Beryllium inbottle purity of 99% or more is used as the anode, and the
cathode is formed by press-forming copper into 0.2 m thickness in the form of & 'JJ diaphragm,
and the cathode base material as shown in 13 in FIG. Using an insulator coated to a thickness of
0.1 m or more as one of the masking layers on one side, electrolysis was performed at a bath
temperature of 25 ° C., a current of 5 A / dm 2, and a current of ff 140000 C / dm 2 with a
direct current. The coated film obtained on the cathode substrate was smooth with metallic
luster, its thickness was about 100 μm, and it was beryllium of 99% purity. The insulator of the
masking layer on the plated cathode substrate was dissolved and removed in an organic solvent
by J, and the copper substrate was washed away with concentrated nitric acid to obtain a
beryllium acoustic imaging plate. (Experimental Example 2) Plating in the same manner as in
Experimental Example 1 except that a polyethylene resin is injection-molded into a thickness of 2
mm in an acoustic diaphragm shape and conductive processing is performed on this surface
using tin oxide to form a cathode substrate. Did. f? Therefore, the thickness of the bonding film
is 100AlTrL, and the metallic gloss and smooth I11! The evil was over 99% beryllium. Plated
cathode) j material was washed and dried and used as an acoustic diaphragm as it was. [Effects of
the Invention] As described above, according to the method of manufacturing a sound 1 m
moving plate of the present invention, a conductive base material is formed corresponding to the
shape of the acoustic diaphragm, and on this base material for the acoustic diaphragm Since the
total bending is electrodeposited by cold plating in a molten salt containing the metal halide for
the acoustic diaphragm, 13 and an alkyl pyridinium halide to form an acoustic diaphragm, the
molten salt bath and By doing this, metals having a high oxygen affinity, which conventionally
had difficulty in normal temperature form electrodeposition, can be easily processed, and a highperformance acoustic diaphragm can be manufactured extremely easily. In addition, highperformance acoustic diaphragms can be realized by using beryllium, brass or titanium.
Furthermore, molding of any shape and control of film thickness can be carried out easily and
accurately, which 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 practicing
the present invention, and FIGS. 2 and 3 are sectional views showing an example of a cathode
substrate used in the present invention.
DESCRIPTION OF SYMBOLS 1 ... Plating tank, 7 ... Cathode base material, 8 ... Plating bath, 9 ...
Anode, 11 ... ilf source, 12 ... Cathode base material, 13 ... Cathode base material .