JPH0423609B2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a method for processing ceramics.

[Conventional technology and its problems]

What is generally called ceramics includes
Single-phase ceramics mainly composed of one type of compound such as oxide, nitride, carbide, boride, silicide, fluoride, sulfide, selenide, terrellide, etc., and two or more types of the above ceramics. Composite ceramics consisting of compounds, as well as natural or artificial powdered compounds such as oxides, carbides, or boride-based cermets, which are made by adding metals to the above ceramics, are molded and fired at high temperatures, and are made from metals and nonmetallic elements. There are polycrystalline solid materials made of inorganic compounds.

Most of these ceramics generally have a higher melting point than metals, have a higher free energy of formation (bonding energy), are extremely chemically stable, and have high hardness, so it is difficult to mechanically In order to process the material, the only way to process it is to use a cutting tool or drill that has cutting chips such as diamond or CBN (cubic boron nitride) or abrasive grains as a cutting edge, or an ultra-hard tool such as a grinding wheel. Its cutting or grinding performance is significantly lower than that of metals and alloys, and it is brittle and easily cracked, so it is not suitable for processing and forming by mechanical cutting or grinding.

In addition, this type of ceramic is generally referred to as an insulator, and its electrical conductivity is significantly lower than that of metals and alloys, and its thermal conductivity is also extremely low, so it cannot be used with diamond chips or abrasives. The energy required for cutting or grinding with a tool having grains is transmitted to the tool side more than when machining thin materials such as metals and alloys, and therefore the wear and damage on the tool side is less than when processing thin materials such as metals and alloys. It is often much larger than in the case of machining.

As described above, ceramics have a high melting point, high hardness, but break easily, low electrical conductivity, and are chemically stable, making them extremely difficult to process using conventional processing methods. It is known to be a material.

[Problem that the invention seeks to solve]

Chemically stable compounds such as metal oxides used in ceramics generally have superior acid and alkali resistance compared to ordinary metals and alloys; In the high temperature range, the reactivity is as high as that of metals, alloys, etc. That is, as is generally known, ordinary metal oxides are difficult to react with acids (e.g., strong acids such as sulfuric acid), alkalis (e.g., Dissolves in strong alkalis (such as sodium hydroxide).

However, even if a chemical reaction using high-temperature acids, alkalis, etc. as described above is applied to ceramics, reliability must be ensured, such as containers that can withstand such high-temperature acids, alkalis, etc., and supply/recovery methods. In addition, with the prior art, it was difficult to cause this chemical reaction to act only on a desired local portion of the ceramic workpiece.

[Means for solving problems]

The reaction action of such high-temperature acids, alkalis, or salts is applied locally to the desired processed part of the ceramics, separated from other surrounding parts, and then the processed part is removed by some means. If this is possible, it will be possible to process ceramics.

Such processing is not limited to high-temperature acids and alkalis; for example, electrolytes of neutral salts such as NaCl, which produce acid at the positive electrode and alkali at the negative electrode, and chemically active ions, such as halogen ions, are used.
It may also be an embodiment in which Cl ^- or the like is applied to the ceramic under predetermined high temperature conditions to decompose the oxide in the relevant portion. Further, the salt, which is a solid ionic crystal placed in the desired processing area, was heated above its melting point to melt it into a molten salt, and maintain a predetermined high temperature condition to make it ready for processing. The molten salt has a hydrated salt containing water of crystallization, an acidic salt containing hydrogen ions, and a basic salt containing hydrogen ions in its salt composition.
It is selected depending on the ceramic to be processed.

Furthermore, a solution of this molten salt to which an acid or alkali is added is used as an electrolytic processing fluid.

The present invention has been made based on the above-mentioned viewpoint, and uses an electrolytic processing liquid in which an electrolyte such as an acid or alkali is dissolved in water, which is usually a solvent, to a unit local area of the surface area of a desired processing part of a ceramic workpiece. A desired unit amount of molten salt is supplied by spraying, flowing down, dropping, etc., or electrical energy is supplied to the local area to generate electric discharge and a high temperature state, and furthermore, to generate an electrolytic action. Preferably, all or most of the acid, alkali, salt, etc. in the supplied electrolytic machining fluid reacts with the ceramics at high temperature in the local area. and mechanically remove the altered products or residues resulting from this reaction, or the reaction parts weakened by the reaction, from the local area using an ultrasonic vibration machining tool to which ultrasonic vibration energy is applied. The processing is carried out by sequentially controlling and moving the processing local part to a predetermined position in the horizontal plane or in the thickness direction of the ceramic object to perform the desired target processing.

In addition, the present invention is not a simple processing in which conventional processing methods such as electrical processing, ultrasonic processing, and chemical processing are individually applied, but the processing methods described above are applied not only to the characteristics and characteristics of each processing method, but also to In other words, for example, applying one processing method to the same part of the workpiece at approximately the same time or immediately after applying another processing method,
Alternatively, ceramic processing can be carried out by a composite processing method, such as applying two or more processing methods alternately, in which the processing effect or effect of one processing method remains, while the other processing method is applied. This overcomes the difficulties.

[Effect]

With the above configuration, ultrasonic machining does not require a cooling liquid to collect and remove high-temperature acids, alkalis, salts, etc. from the processing section, even if there is a certain amount of recovery. In some cases, the amount can be extremely small, and there is almost no possibility that the electrolytic machining fluid to be recovered is in a high temperature state, so it is possible to construct a machining device that achieves the object of the present invention. Become.

In the present invention, electrolytic discharge energy (accompanied by combined effects such as electrochemical action due to electrolysis, energization heating action due to electricity supply, and heat and impact action due to discharge) is used as the energy supplied to the desired machining part, This is applied to a predetermined local range of, for example, several 10 μm to 1 μm, and no heat or the like is applied to other areas, making it possible to perform local processing.

In addition, the ceramic material to be processed has poor thermal conductivity.
Since there is relatively little thermal diffusion from the local part of the process, the reaction with the acid, alkali, salt, etc. heated to high temperature in the present invention is carried out locally.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

The drawing is an explanatory diagram showing one embodiment of a processing device used when carrying out the method of the present invention.

In the figure, 1 is a machining fluid supply nozzle, 2 is one electrode provided at the tip of the machining fluid supply nozzle 1, 3 is an arm, 4 is the other electrode attached to the arm 3,
5 is an ultrasonic vibrator, 6 is a horn attached to one end of the ultrasonic vibrator 5, 7 is an ultrasonic machining tool attached to the tip of the horn 6, and 8 is a workpiece.

The machining fluid supply nozzle 1 has a wide and flat end spout, and one electrode 2 (+
The other electrode 4 (-pole) is provided at the tip of the arm 3 extending forward from the nozzle 1.
It is provided so as to be in contact with the electrolytic machining fluid spouted from the nozzle 1.

The ultrasonic vibrator 5 is attached to the arm (not shown) of the ultrasonic processing machine and converts high frequency current into mechanical vibration, and the horn 6 provided at one end of the ultrasonic vibrator 5 converts the amplitude of this vibration. It is enlarged and transmitted to the tool 7 attached to the tip.

The workpiece 8 is attached to a cross slide table (not shown) and is configured to be moved to any position on a horizontal plane under servo control.

Then, for example, hydrochloric acid (HCl) with a concentration of 5 to 40% is supplied from the processing liquid supply nozzle 1 at a speed of about 10 m/s to
The electrolytic machining fluid is sprayed in a film shape according to the machining area by the ultrasonic machining tool 7 at a flow rate of approximately 1 to 10 c.c. A DC, AC, high frequency, or intermittent voltage pulse voltage is applied between the electrode 4 and the other electrode 4 (-pole), and the electrolytic working fluid is brought to a predetermined high temperature state by energization, electrolysis, and discharge. It is supplied in a heated state to the surface of the ceramic to be processed of the ceramic workpiece 8 to cause decomposition of the ceramic, a reaction layer, and an embrittlement layer 8a, and at the same time, the workpiece 8 is controlled to move sequentially in the direction of the arrow in the figure. Lever layer 8
A is brought into light contact with the ultrasonic machining tool 7 to apply ultrasonic vibration energy, thereby performing ultrasonic vibration grinding and removal.

If necessary, abrasive grains mixed and dispersed in light oil or the like may be supplied between the ultrasonic machining tool 7 and the workpiece 8 by an appropriate means according to the conventional means of ultrasonic machining. You may let them.

Further, the electrolyte in the electrolytic machining fluid supplied from the machining fluid supply nozzle 1 does not necessarily have to be a strong acid or a strong alkali, and may be a neutral salt such as sodium chloride or potassium chloride. Electrolysis produces acid at the positive electrode and alkali at the negative electrode, producing similar effects.

Composition SiC with small amounts of SiO ₂ , CaO, K ₂ O, TiC,
Adding Na ₂ CO ₃ to conductive SiC ceramics containing TiN
The aqueous solution containing 40% flows out from the nozzle and connects to electrodes 2 and 4.
When electricity is applied between Na ₂ CO ₃ and heated to an extent that it does not boil, SiO ₂ , CaO, K ₂ O, etc. present at the grain boundaries in the ceramic SiC react with the alkaline corrosive liquid to form silicates. , the erosion becomes significant and workability is imparted.

Similarly, when molten NaOH as an electrolytic processing fluid flows out of a nozzle and is heated, SiO ₂ at the ceramic grain boundaries easily reacts with the high-temperature NaOH solution.
It becomes sodium silicate, melts, and progresses in erosion, giving it workability. The electrolytic machining fluid Na ₂ CO ₃ and K ₂ CO ₃ rapidly eroded from about 70.0℃, and the electrolytic machining fluid
In the case of NaNO ₃ , erosion starts at 450°C, but in both cases, the erosion becomes good at 850°C.

In addition, from the processing fluid supply nozzle 1, crystals of non-liquid sodium bicarbonate NaHCO ₃ , acid salts of potassium hydrogen fluoride KHF ₂ , basic salts such as magnesium chloride hydroxide MgCl(OH), or sodium carbonate hydrate are supplied. Direct _{current , alternating} current, _{high frequency} or By applying intermittent voltage pulses to turn the crystals into molten salt and keeping the electrolytic working fluid at a predetermined high temperature, the ceramic decomposes and a reaction layer is formed on the surface of the ceramic workpiece 8. , an embrittlement layer 8a is formed, which is then processed using an ultrasonic processing tool or ground using a grindstone (not shown), as described above.

〔Effect of the invention〕

According to the present invention, an electrolytic machining fluid such as an acid, alkali or salt is heated to a high temperature by energizing and energizing with electric energy, and further electrolyzed, and locally supplied onto the ceramic workpiece. This is a special process in which at least a portion of the ceramic workpiece is decomposed, melted, or otherwise reacted, partially weakened, and then that portion is mechanically removed using an ultrasonic processing tool that is applied with ultrasonic vibration energy. By applying a complex processing method, it is now possible to perform processing such as drilling, engraving, cutting, and forming grooves on ceramic workpieces, as well as processing using diamond-free grindstones, which was previously considered impossible, and can be applied to a wide range of areas. This makes it possible to easily and inexpensively provide ceramic products that are expected to be used in

In addition, when the electrolytic machining fluid is supplied in a certain amount or more, if the stage for the ceramic workpiece is used as one electrode and the ultrasonic machining tool is used as the other electrode and electricity is applied, the ultrasonic machining will be performed. Since the object of the present invention can be achieved by generating a micro discharge mainly around the tip of the tool near the workpiece, the electrodes 2, 4, etc. are not essential components of the present invention.

[Brief explanation of drawings]

The drawing is an explanatory diagram showing one embodiment of a processing device used when carrying out the method of the present invention. 1... Machining liquid supply nozzle, 2... One electrode,
3... Arm, 4... Other electrode, 5... Ultrasonic vibrator, 6... Horn, 7... Ultrasonic machining tool, 8... Workpiece.

Claims (1)

[Scope of Claims] 1. The above-mentioned processing is carried out by supplying an electrolytic processing liquid to the surface region of the desired processing portion of the ceramic workpiece and applying electrical energy to the surface region of the processing portion with the electrolytic processing fluid interposed therein by dipping or the like. 1. A method for processing ceramics, which comprises altering a portion of the ceramic, and then subjecting the altered portion to ultrasonic machining using an ultrasonic vibration machining tool that applies ultrasonic vibration energy to the altered portion. 2. The method of processing ceramics according to claim 1, wherein the electrolytic processing fluid is a processing fluid in which an electrolyte is dissolved in water. 3. The method of processing ceramics according to claim 1, wherein the electrolytic processing fluid is a dissolved salt heated and melted. 4. The method for processing ceramics according to claim 1, wherein the electrolytic processing fluid is an acid. 5. The method of processing ceramics according to claim 1, wherein the electrolytic processing fluid is a base. 6. The method of processing ceramics according to claim 1, wherein the electrolytic processing fluid is a salt. 7. The method of processing ceramics according to any one of claims 1 to 6, wherein the electrical energy applied to the surface area of the processed part is a current passed through the electrolytic processing fluid. 8. The ceramic according to any one of claims 1 to 6, wherein the electrical energy applied to the surface area of the processed part is energy provided by electric discharge between a pair of electrodes provided close to the surface of the processed part. processing method.