JP4749993B2 - Tungsten alloy - Google Patents

Description

  The present invention relates to a tungsten material imparted with oxidation resistance, and preferably relates to a tungsten material used for high-temperature applications such as a filament of a halogen lamp, a tungsten mesh heater or the like.

  Since tungsten having the highest melting point among metals is suitable for use under severe high temperatures, it is typically widely used as a material for lamp filaments (also called coils). As a tungsten material used for such a lamp filament, a doped tungsten wire containing an additive such as aluminum oxide, silicon oxide, or potassium oxide is known.

  However, in this doped tungsten wire, recrystallization proceeds during use, and crystal grains become extremely coarse, so that it becomes extremely fragile even at room temperature. For this reason, the doped tungsten wire does not have sufficient strength against vibration. Conventionally, a tungsten wire in which a doped tungsten material contains rhenium, thorium, tantalum carbide, and gadolinium in several percent to several tenths of a percent is used. Has been developed. (See Patent Document 1 and Patent Document 2).

  Halogen lamps add a small amount of halogen compounds to the gas sealed inside the lamp so that the inside of the miniaturized quartz tube is not blackened by tungsten evaporated from filaments made of tungsten wire, and the temperature of the light emitting part and the tube wall Purification by the tungsten halogenation cycle due to the difference is performed. The halogen lamp repeatedly flashes and lights up, and the filament repeats contraction in the axial direction, thereby reaching a life due to disconnection accompanying a decrease in grain boundary strength.

  Here, the lifetime of the lamp includes blackening in the bulb and breakage of the filament. As described above, blackening refers to a decrease in luminance due to deposition of evaporated tungsten on the glass surface. Also, the filament breakage is a phenomenon in which the lamp is not energized at all due to the consumption of tungsten or destruction due to vibration, and the lamp is not energized at all and does not emit light.

  In the halogen lamp, a small amount of oxygen is enclosed in the tube in order to prevent blackening, that is, to activate the halogen cycle. However, although this oxygen is useful for reducing the normal blackening, there is a problem that the tungsten filament is oxidized and its life is shortened.

JP-A 61-135445 JP-A-3-44443

  Therefore, in view of the above problems, the technical problem of the present invention is to improve the characteristics of tungsten, which is a refractory metal, to have oxidation resistance, and extend its life even when a small amount of oxygen is present. It is to provide a tungsten alloy that can be used.

  In order to solve the above-mentioned problems, the present inventors have conducted extensive research. As a result, at least one of titanium and titanium oxide is mixed with a tungsten raw material, and the tungsten material is mixed with at least one of titanium and titanium oxide. It has been found that by dispersing seeds, the oxidation resistance can be improved while strengthening the high-temperature strength, and the present invention has been completed.

That is, according to the present invention, a tungsten alloy having oxidation resistance, containing titanium oxide in the range of 10 ppm to 1% by mass as the amount of metal titanium , the balance being composed of tungsten and inevitable impurities. A characteristic tungsten alloy is obtained. Further, according to the present invention, the tungsten alloy has oxidation resistance, and the total amount of metal titanium and titanium oxide in the range of 35.6 ppm to 1 mass% as the amount of metal titanium is used as the amount of metal titanium. A tungsten alloy containing 95 mass ppm or more and 1 mass% or less in which the balance is made of tungsten and inevitable impurities is obtained.

Further, according to the present invention, there is provided a tungsten alloy having oxidation resistance, titanium oxide, metal titanium amount, 10 ppm by mass or more, contained in a range of 1 mass%, further, 0 in weight ratio. A tungsten alloy containing 003 to 0.1% of at least one of aluminum, potassium, and silicon oxides, the balance being tungsten and unavoidable impurities can be obtained. Further, according to the present invention, the tungsten alloy has oxidation resistance, and the total amount of metal titanium and titanium oxide in the range of 35.6 ppm to 1 mass% as the amount of metal titanium is used as the amount of metal titanium. Containing at least 95 ppm by mass and not more than 1% by mass, and further containing at least one of 0.003 to 0.1% by mass of aluminum, potassium, and silicon oxides, A tungsten alloy characterized in that the balance consists of tungsten and inevitable impurities is obtained.

  ADVANTAGE OF THE INVENTION According to this invention, the tungsten alloy which improved the characteristic so that it might have oxidation resistance by making tungsten which is a high melting point metal contain at least 1 sort (s) of titanium and titanium oxide can be provided.

  Further, according to the present invention, since the tungsten alloy is excellent in oxidation resistance, it is possible to provide a member having excellent oxidation resistance characteristics as a high-temperature furnace part such as a heater and a reflector.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1A is a view showing an example of a halogen lamp according to the embodiment of the present invention, and FIG. 1B is a view showing another example of the halogen lamp according to the embodiment of the present invention. Referring to FIG. 1A, a halogen lamp 101 includes a cylindrical quartz glass tube 7 having a protrusion on the upper end surface, a coil portion 1 and leg portions 2 connected to both ends of the coil portion 1, and externally. The two external leads 6 to be led out, the molybdenum foil 5 for connecting the end of the leg 2 and one end of the external lead 6, respectively, and the quartz glass tube 7 are provided around the connecting portion near the molybdenum foil. Therefore, the coil part 1 is enclosed together with a part of the leg part 2 inside the quartz glass tube 7. Incidentally, a halogen gas is sealed inside. This filament type is called C-6.

  Referring to FIG. 1B, the halogen lamp 102 has a cylindrical quartz glass tube 16 having a rounded upper end surface and a sharp projection on the front end surface, a tungsten filament 11 made of a tungsten wire, and tungsten. L-shaped struts 12 and 13 for supporting the filament 11 in the axial direction of the tube and supporting the tip portion and the base portion, respectively. The strut is further externally connected from the sealed portion sealed together with the opening of the tube 16. The external leads 15 and 15 are formed. Incidentally, a halogen gas is sealed inside. This filament type is shown in JIS C7711.

  The present invention will be described in more detail. In the present invention, titanium tungsten is contained in a tungsten filament by introducing metal titanium powder as a doping material to a tungsten material produced by a usual powder metallurgy method. This improves the oxidation resistance.

  The tungsten wire constituting the coil part 1 or the tungsten filament 11 of the halogen lamp 101 or 102 according to the present invention contains titanium. Since the titanium content is very small, it is very difficult to analyze the bonding state with tungsten. However, there is a possibility that metal titanium reacts with titanium hydride in a reducing atmosphere in the production process. However, calculation of free energy of formation revealed that titanium hydride reacts with titanium oxide in an oxidizing atmosphere.

For example, in the reaction of TiH ₂ + O ₂ → TiO ₂ (rutile) + H ₂ , the free energy of formation is −775000 J / mol at 500K.

For example, in the reaction of TiH ₂ + O ₂ → TiO ₂ (anatase) + H ₂ , the free energy of formation is −771000 J / mol at 500K.

  If the sign of the calculation result is negative, a chemical reaction occurs in the direction of the arrow.

Accordingly, titanium hydride itself has a reducing action when oxidized, and titanium oxide having a small number of oxygen bonds, such as TiO, Ti ₂ O ₃ , Ti ₃ O ₅ , Ti ₄ O _7, etc. There is room for oxidation reaction to TiO ₂ , that is, reducing action of the lamp and tungsten filament. Further, even in the case of TiO _{2 having} a rutile structure, there is a reducing ability even when changing to an anatase structure. In the present invention, the same effect was obtained even when TiO ₂ was added at the time of charging because titanium dioxide was partially reduced by the hydrogen reduction atmosphere during high-temperature sintering during the manufacturing process of tungsten wire. It is presumed that the particles can be present as dispersed particles having a reducing action by a reaction that undergoes thermal decomposition. Note that the reduction action of titanium in tungsten is not so great as to hinder the activation of the halogen cycle, but it is considered that the range of the present invention has a suitable range that hinders the oxidation of tungsten itself.

  In the present invention, an extremely long-life tungsten filament can be obtained by doping with titanium or titanium oxide.

  Here, when the doping amount of titanium in tungsten is less than 10 mass ppm, the effect of preventing oxidation cannot be obtained. On the other hand, when the doping amount of titanium exceeds 1% by mass, the high temperature strength of tungsten is lowered, and the processing yield during production is extremely lowered. Accordingly, a sufficient effect is obtained if it is 10 mass ppm or more to 1 mass% or less, and the lamp life (lamp blackening, filament breakage), preferably 30 mass ppm or more to 100 mass ppm or less, It is advantageous because of the interlocking structure.

  In applications that do not require earthquake resistance, an interlock structure by adding oxides of aluminum, potassium, and silicon that promote blackening as an impurity element is unnecessary.

  Hereinafter, a specific example of manufacturing a tungsten wire according to an embodiment of the present invention will be described.

(Example 1)
First, as a first step, a metal titanium powder and a titanium oxide powder that were sieved to a predetermined amount of purity 99.9% or more and 70 μm or less were prepared. The particle size of the titanium powder is not particularly limited. This metal titanium powder and titanium oxide powder are dry-mixed with pure tungsten having an Fsss particle size of 5 μm or tungsten powder having an Fsss particle size of 5 μm containing 0.01% by mass of oxides of aluminum, potassium and silicon for 5 hours, and pressing. After molding, ingots were produced by sintering in a hydrogen atmosphere at 1800 ° C. to 2500 ° C. for 3 hours. The ingot was heated in the range of 1000 ° C. to 1600 ° C. and swaged. Here, the reason for sintering in a hydrogen atmosphere (non-oxidizing atmosphere) is that tungsten cannot be manufactured due to oxidation and sublimation when sintering is performed in an oxidizing atmosphere.

  A tungsten rod was formed by hot drawing using a carbide die and a diamond die. Table 1 shows the results of measuring the amount of titanium after manufacturing a tungsten wire having a diameter of 1.0 mm based on JIS H 1403 by ICP emission spectroscopic analysis and the results of lifetime.

(Characteristic evaluation)
The results of the corrosion resistance test and the high temperature tensile test are shown in the accompanying drawings.

  FIG. 2 shows the results of a tensile test in which the tungsten material of the present invention and the material with the titanium remaining amount of 90 ppm of Example 1 of the present invention were drawn to a diameter of 0.5 mm and heated to each temperature for 20 seconds. In FIG. 2, it has been found that the material of the present invention has a strength comparable to that of the conventional tungsten material containing oxides of aluminum, potassium and silicon. Moreover, it became clear from FIG. 2 that the material of the present invention has a high temperature strength that exceeds that of a conventional tungsten material because the grain boundary strength is improved. The tensile speed of the tensile test was 1.0 mm per minute.

  FIG. 3 shows a sample of the tungsten wire of the present invention having a diameter of 1.0 mm, the material of Example 1 having a titanium remaining amount of 90 ppm cut into 200 mm, heated to 1100 ° C. in the atmosphere and oxidized to obtain 20% NaOH. The result of measuring the weight loss (oxidation amount) by boiling in an aqueous solution to dissolve the oxide is shown. In FIG. 3, the oxidation state is difficult to discriminate the oxidation state by weight measurement because the increase due to surface oxidation and the decrease in oxide proceed simultaneously. Therefore, the weight loss obtained by boiling a sample oxidized at 1100 ° C. in the atmosphere in a 20% aqueous solution of NaOH was graphed with the weight loss after 660 seconds of the tungsten rod as 100. From the results of FIG. 3, it can be seen that the tungsten rod of the present invention is superior in oxidation resistance as compared with conventional tungsten.

  Table 1 below shows the results of a life test in which tungsten filaments of the present invention were used and a tungsten filament produced by a conventional method was mounted on a general 100 V 1000 W halogen lamp and turned on for 2 seconds and turned off for 2 seconds repeatedly. . The filament type was C-8 type, according to JIS C7711. FIG. 1 shows the structure.

  As shown in Table 1 above, Samples 1 to 4, 6 to 10, and 12 to 14 containing metal titanium or titanium oxide of the present invention in tungsten have a lifespan of blinking times as compared with Comparative Examples 17 to 20. It turns out that it has improved markedly. In addition, the number of breaks during filament processing can be greatly reduced, and it was confirmed that the material is excellent in productivity.

  In the above description, a technique for obtaining a tungsten wire specifically used for a halogen lamp has been described. However, the present invention has a tungsten electrode inside a glass tube, and a metal halide lamp, Of course, the present invention can also be applied to a xenon discharge lamp, a xenon mercury discharge lamp, a discharge lamp in which cadmium or zinc is sealed in an arc tube or a high pressure mercury lamp.

  Also, based on the idea of the present invention, even if the high temperature strength of tungsten is slightly reduced, when it is desired to obtain an application material that gives priority to corrosion resistance and oxidation resistance, it is possible to increase the titanium content appropriately. Of course.

  The tungsten alloy according to the present invention is most suitable for a member requiring corrosion resistance, such as a tungsten filament used for a filament of a halogen lamp.

(A) is explanatory drawing which shows an example of the halogen lamp by embodiment of this invention. (B) is explanatory drawing which shows another example of the halogen lamp by embodiment of this invention. It is a figure which shows the result of the high temperature tensile test of the tungsten wire by embodiment of this invention. It is a figure which shows the oxidation resistance test result of the tungsten wire by embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Coil part 2 Leg part 3 Tungsten wire 4 Sealing part 5 Molybdenum foil 6 External lead 7 Quartz glass tube 11 Tungsten filament 12, 13 Support | pillar 15 External lead 16 Quartz glass tube 101, 102 Tungsten filament

Claims (4)

A tungsten alloy having oxidation resistance, characterized in that it contains titanium oxide in the range of 10 ppm or more and 1% by mass or less as the amount of metal titanium , and the balance consists of tungsten and inevitable impurities. It is a tungsten alloy having oxidation resistance, and the total amount of metal titanium and titanium oxide in the range of 35.6 ppm to 1 mass% as the amount of metal titanium is 95 mass ppm to 1 mass% as the amount of metal titanium. A tungsten alloy containing in the following range , the balance being tungsten and inevitable impurities. A tungsten alloy having oxidation resistance, containing titanium oxide in the range of 10 ppm by mass or more and 1% by mass or less as the amount of titanium metal, and 0.003 to 0.1% aluminum by mass ratio, A tungsten alloy comprising at least one of potassium and silicon oxides, the balance being tungsten and inevitable impurities . It is a tungsten alloy having oxidation resistance, and the total amount of metal titanium and titanium oxide in the range of 35.6 ppm to 1 mass% as the amount of metal titanium is 95 mass ppm to 1 mass% as the amount of metal titanium. It is contained in the following range, and further contains 0.003 to 0.1% by mass ratio of at least one of aluminum, potassium, and silicon oxides, with the balance being tungsten and inevitable impurities. A tungsten alloy characterized by

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