JPS6048042B2 - Method for manufacturing a vibrating body for an acoustic transducer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a vibrating body for an acoustic transducer, and in particular, the Young's modulus ) or a method of manufacturing a high-performance vibrating body for an acoustic transducer with a high ratio of Young's modulus E to density ρ.

Conventionally, the materials used for the above-mentioned vibrating bodies are often aluminum, titanium, etc., which are lightweight and easy to roll. A specific vibration mode occurs throughout the vibration system, causing a large peak in the high frequency response, which significantly impairs sound quality.In the case of cantilevers for record player cartridges, the cantilever accounts for most of the effective mass of the vibration system. Therefore, it has been extremely difficult to reduce the effective mass of the vibration system, which is necessary to improve the performance of the cartridge.

That is, when the thickness and diameter of the vibrator are reduced in an attempt to reduce the weight of the cantilever, the rigidity decreases and the characteristics deteriorate.

To improve the above characteristics, the ratio of Young's modulus E to density ρ is E/ρ.
This can be achieved by using a material with a large specific elastic modulus (hereinafter referred to as specific modulus). Materials with a large specific elastic modulus ratio E/ρ include boron, beryllium, etc., but boron is difficult to obtain (especially high quality ones), and beryllium requires a large amount of money for pollution prevention equipment in the manufacturing process. do.
Further, boron and beryllium are difficult to process by rolling, pressing, etc., and forming them into a predetermined shape requires a large amount of cost, and the shape is also severely limited.
Therefore, an easily molded material such as aluminum or titanium is molded into a predetermined shape, and the molded material is used as a base material and is coated with boron, beryllium, etc. by physical vapor deposition or chemical means. It is possible to obtain plates, cantilevers, etc.

By the way, by physical vapor deposition or chemical means! When forming a coating layer on a vibrating substrate, it is desirable to heat the vibrating substrate to 150°C or higher in order to improve the properties of the deposited film, but in this case, the thermal expansion coefficients of the vibrating substrate and the coating layer are significantly different. After cooling, mechanical distortion may occur or cracks may occur in the coating layer, making it unusable. It has also been proposed to provide a coating layer of beryllium or boron on the vibrating base by vapor deposition or the like, and to peel only this coating layer from the base to form a vibrating body of beryllium or boron. The beryllium or boron coating layer produced by Beryllium or Boron has the disadvantage of having low mechanical strength and being easily broken.

In addition, in order to form a coating layer on a vibrating substrate by means such as vapor deposition, an evaporation device such as electron beam heating is required, which requires a large amount of equipment and a long production time, resulting in a very high product cost. It gets expensive. Therefore, a vibrating body for an acoustic transducer has been proposed in which boron is diffused in the base by forming a coating layer of boron on the vibrating base and heat-treating the coating layer.

However, the vibrating body for an acoustic transducer according to this proposal is
It is characterized by forming a diffusion layer on the vibrating base, and in forming this layer, a coating layer of a diffusive substance is used to create the diffusion layer on the vibrating base using physical vapor deposition or chemical means. The manufacturing process requires a very large amount of equipment to form the diffusion layer, and if the coating layer that becomes the diffusion layer is made of a material such as boron that has a very high boiling point and is difficult to process, it is necessary to form the coating layer on the vibrating substrate. This has disadvantages in that it takes a long time to process and the manufacturing cost is high, resulting in a very high product cost of the vibrating body for an acoustic transducer. Furthermore, the heat treatment temperature for forming the diffusion layer on the vibrating base is extremely high (9000C to 1300'C when titanium is used for the vibrating base and boron is used as the diffusion material), which causes mechanical strain and deformation in the base. This resulted in problems such as cracks and cracks that had to be taken care of. As a solution to these drawbacks, a method has been proposed in which a boron layer is formed on the vibrating substrate by chemical vapor deposition.

This method uses hydrogen gas as a carrier gas,
Boron is precipitated from boron chloride gas (BCe3), but when hydrogen gas is used, it reacts with titanium to form titanium hydride, making it extremely brittle and unusable as a vibrating body. The present invention was made to overcome the above-mentioned drawbacks, and its main purpose is to enable mass production at low cost without coating the vibrating base, which is to become a vibrating body, with a diffusion material, and to reduce the variation in characteristics. An object of the present invention is to obtain a high-performance vibrating body for an acoustic transducer having a diffusion region of a diffusive material in a vibrating base by providing an effective means for permeating and diffusing a diffusing material into a base with a small amount.

Another object of the present invention is to provide an acoustic transducer that does not cause deformation or cracks caused by mechanical strain on the vibrating base when forming a diffusion region of a diffusion material on the vibrating base to become a vibrating body. An object of the present invention is to provide a method for manufacturing a vibrating body.

Next, a method for manufacturing a vibrating body for an acoustic transducer according to the present invention will be explained in detail with reference to the drawings. Generally, when the vibrating base material is heated, it becomes highly activated, and unless it is in a reducing gas atmosphere, the surface will oxidize, making it impossible to form a boron layer.

For this reason, it is conceivable to use hydrogen gas as a carrier gas, but in practice this cannot be used due to the drawbacks mentioned above (particularly when titanium is used as the substrate). Therefore, one feature of the present invention is that carbon monoxide gas is used as the carrier gas. The figure is a configuration diagram showing one embodiment of an apparatus used in the method of the present invention. First, a vibrating base 1 formed in the shape of a vibrating body for an acoustic transducer for each purpose is appropriately set in a reaction tube 3 equipped with an automatic temperature controller 2. Although inorganic solid substances such as titanium, zirconium, yttrium, and vanadium can be used as the vibrating base material, an embodiment using titanium will be particularly described in the present invention. A raw material gas 4 and carbon monocarbonate (CO) 5 as a carrier gas are mixed at an appropriate mixing ratio and introduced into the reaction tube 3 set in this way using flowmeters 6 and 6'', respectively. The substrate is heated to a temperature of 900'C to 1200°C by applying electricity to the substrate.Boron chloride (BCf3) and boron bromide (B
Br3), boron iodide (BI3), boron fluoride (BF3)
), etc., but in the present invention, a case in which boron chloride (BC'3) is used will be explained in particular.
In this way, a mixed gas of raw material gas 4 and carrier gas 5 is passed through the reaction tube 3 in which the vibrating base 1 is set, and heated, and boron, which is a diffusion material, is deposited as a coating layer on the surface of the titanium vibrating base. At the same time, it permeates and diffuses into the vibrating base to form a diffusion layer. The above diffusion layer forms an intermetallic compound of boron and titanium, and the intermetallic compound thus formed is mainly titanium boride (TlB2), and the Young's modulus E of titanium boride is 58,000k9/
It is extremely large in rank 2, reaching about five times that in the case of titanium alone. Since the specific gravity p of titanium boride is approximately 3.8y/Cc, the specific elastic modulus (E/ρ) is 1.5×10 10 −. This value is approximately equivalent to the specific elastic modulus of boron. On the other hand, if a boron layer is provided on a titanium vibrating base and a double-structure vibrating body made of the boron layer and titanium is manufactured, the apparent Young's modulus and density will be a combination of those of titanium and boron. , the specific elastic modulus is always lower than the value of boron, and is inferior to the specific elastic modulus of a material with boron diffused therein.

Therefore, a vibrating body with higher performance can be obtained by using the method of the present invention in which almost all of the boron precipitated from boron chloride (BCe3) gas is diffused into the titanium vibrating base. In this way, in order to diffuse almost all of the boron deposited on the surface of the titanium vibrating base into the interior of the titanium vibrating base, it is necessary to make the precipitation rate of boron extremely slow. The mixing ratio of carbon (CO) carrier gas and boron chloride (BC'3) gas is 20:1, and approximately 2f
/Min. When the reaction tube was allowed to flow through the reaction tube (inner diameter of about 60φ) for about 2 minutes at a flow rate of In the above experiment, the temperature of the reaction tube was 1000'
I chose C. At a flow rate and time less than the above, almost all of the deposited boron is diffused into the titanium vibrating base, and no boron layer is formed on the surface of the vibrating base. In addition to boron, the diffusion materials to be coated include silicon, carbon, etc., which are inorganic solid substances.

According to the method for manufacturing a vibrating body for an acoustic transducer of the present invention as described above, since carbon monoxide is used as a reducing carrier gas, oxidation of the vibrating base can be prevented, and the combination of titanium and carrier gas can be prevented. Stable boron precipitation, deposition, and therefore diffusion can be ensured without causing any reaction.

Furthermore, according to the method of the present invention, highly toxic boron chloride (
BC'3) The amount of gas used is small, the manufactured vibrating body has only a slight increase in thickness, and the change in dimensions is small, and there is no need to control or remove the thickness of the deposited boron layer. Therefore, the process is simplified, and a vibrating body for an acoustic transducer with little variation and high performance can be obtained.

[Brief explanation of the drawing]

The figure is a configuration diagram showing one embodiment of an apparatus used in the method of manufacturing a vibrating body for an acoustic transducer according to the present invention. 1... Vibrating base, 3... Reaction tube, 4...
... Raw material gas, 5 ... Carbon monoxide gas.

Claims (1)

[Claims] 1. A step of preparing a vibrating base to be a vibrating body for an acoustic transducer made of an inorganic solid material and formed into a desired shape, and applying a raw material gas containing boron as a diffusion material to the heated vibrating base. A step of introducing a mixed gas mixed with carbon monoxide as a carrier gas, and a step of precipitating a diffusion material in the source gas onto a vibrating base in the mixed gas atmosphere and diffusing the precipitated diffusion material into the vibrating base. The flow rate of the source gas containing boron is restricted so that the amount of diffusion material diffused into the vibrating base is greater than the amount of diffusion material deposited on the surface of the vibrating base within a certain period of time. A method for manufacturing a vibrating body for an acoustic transducer. 2. The method for manufacturing a vibrating body for an acoustic transducer according to claim 1, characterized in that titanium or a titanium-containing material containing titanium as a main component is used as the vibrating base material. 3. The method for manufacturing a vibrating body for an acoustic transducer according to claim 1, characterized in that zirconium or a zirconium-containing material containing zirconium as a main component is used as the vibrating base material. 4. The method for manufacturing a vibrating body for an acoustic transducer according to claim 1, characterized in that yttrium or an yttrium-containing material containing yttrium as a main component is used as the vibrating base material. 5. The method for manufacturing a vibrating body for an acoustic transducer according to claim 1, characterized in that vanadium or a vanadium-containing material containing vanadium as a main component is used as the vibrating base material. 6. The method for manufacturing a vibrating body for an acoustic transducer according to claim 1, wherein the raw material gas is made of boron chloride (BCl_3). 7. The method for manufacturing a vibrating body for an acoustic transducer according to claim 1, wherein the raw material gas is made of boron bromide (BBr_3). 8. The method for manufacturing a vibrating body for an acoustic transducer according to claim 1, wherein the raw material gas is made of boron iodide (BI_3). 9. The method for manufacturing a vibrating body for an acoustic transducer according to claim 1, wherein the raw material gas is made of boron fluoride (BF_3).