JP2016144827A - End tab for welding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an end tab for welding, which can be removed after the welding and which has high durability.SOLUTION: An end tab for welding, in which a contact part abutting on at least a member to be welded is made of a ceramic sintered body predominantly composed of silicon nitride, is provided.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a welding end tab.

  Conventionally, when welding the members to be welded, steel end tabs have generally been used as welding end tabs attached to both ends of the welded portion in order to fix the relative positions of the members to be welded. The reason for this is that the welding continuity is maintained, good welding without interruption is possible, and after the end of welding, the steel tab end tab is cut at a position about 5 to 10 mm away from the member to be welded. Because it is good.

  However, steel end tabs must be temporarily fixed to the welded member by welding in advance, and this work is cumbersome and the cutting work after the end of welding takes time and effort. Ceramic end tabs are used.

As such a welding end tab, for example, Patent Document 1 proposes a welding end tab made of a solid flux or a high melting point ceramic, such as a cordierite or a steatite ceramic, or a SiO ₂ —MnO—CaO system. It is described that the flux is used.

JP 61-119398 A

  However, even if the welding end tab proposed in Patent Document 1 is formed of any component, it is easily wetted with the molten metal, so that the molten metal adheres to both the welded portion and the welding end tab. As a result, the welding end tab and the part to be joined are joined, and an extra step such as a step of cutting the adhesion portion is necessary to remove the welding end tab. In addition, the welding end tab described in Patent Document 1 has a problem of low mechanical strength, large changes in shape and strength due to repeated use, and a small number of times of repeated use (low durability). The present invention has been devised in view of the above problems.

  Provided is a welding end tab characterized in that at least a contact portion in contact with a member to be welded is made of a ceramic sintered body mainly composed of silicon nitride.

  The welding end tab of the present invention is easy to remove after welding and has high durability.

It is a perspective view which shows an example of the end tab for welding of this embodiment. It is a perspective view which shows the other example of the end tab for welding of this embodiment. It is a schematic diagram which shows the structure of the ceramic sintered compact which comprises the end tab for welding of this embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, in all the drawings in this specification, the same reference numerals are given to the same parts unless the confusion occurs, and the description thereof is omitted as appropriate.

  FIG. 1 is a perspective view showing an example of a welding end tab of the present embodiment. FIG. 2 is a perspective view showing another example of the welding end tab of the present embodiment. The welding end tab 10 of the example shown in FIG. 1 is used for welding the respective end faces of the first metal member 1 and the second metal member 2 which are plate-like members to be welded. In addition, the end tab 11 for welding in the example shown in FIG. 2 has an end surface of the fourth metal member 4 that is a plate-like member to be welded on one main surface of the third metal member 3 that is a plate-like member to be welded. It is used for welding.

  These welding end tabs 10 and 11 fix the relative positions of the members to be welded and prevent leakage of molten metal to the outside, and both are pressed and supported by the clamp wire 5. The fourth metal member 4 is supported by a backing metal 6 temporarily fixed to the third metal member 3.

  The welding end tabs 10 and 11 are made of a ceramic sintered body whose main component is silicon nitride at least at the contact portion that comes into contact with the member to be welded. Such a ceramic sintered body containing silicon nitride as a main component is difficult to get wet with the molten metal, so that the molten metal is less likely to adhere to the welding end tabs 10, 11. Is difficult to be joined. For this reason, the welding end tabs 10 and 11 can be peeled off with a relatively small force without performing an extra step such as a step of cutting the adhesion portion in order to remove the welding end tabs 10 and 11. Moreover, the ceramic sintered body which has silicon nitride as a main component also has high mechanical strength, and the change of the shape and intensity | strength by repeated use is small. Moreover, the ceramic sintered body which has silicon nitride as a main component has high corrosion resistance with respect to the molten metal. The welding end tab of the present embodiment made of a ceramic sintered body containing silicon nitride as a main component has a small change in shape and strength due to repeated use, and can be used many times (high durability).

  As shown in FIGS. 1 and 2, in particular, the welding end tabs 10 and 11 of the present embodiment are a pair of welding end tabs arranged so as to be in close contact with the members to be welded 1, 2, 3, and 4. The contact portion for sandwiching the members to be welded 1, 2, 3 and 4 is made of a ceramic sintered body mainly composed of silicon nitride.

  Ceramic sintered bodies have low wettability with molten metal. Moreover, if the surface roughness of the welding end tab 10 is large, the wettability is further reduced. In order to lower the wettability to the molten metal, the surface roughness of the ceramic sintered body is preferably larger. In order to further lower the wettability with respect to the molten metal, it is preferable to set the arithmetic average roughness (Ra) of the surface of the ceramic sintered body to, for example, about 1 to 50 μm.

  As a method of increasing the surface roughness of a welding end tab made of a ceramic sintered body containing silicon nitride as a main component, when molding a powder containing silicon nitride as a main component into a desired shape, By applying so-called discharge texture processing on the pressing and pressing surface side, the transfer surface is adjusted to an appropriate surface roughness, and when a ceramic sintered body mainly composed of silicon nitride is baked and hardened, it is several tens of μm higher. What is necessary is just to use the method etc. which adjust to suitable surface roughness by laying a rough covering powder on a shelf board. Also, a method of adjusting the surface roughness by performing blasting using coarse abrasive grains of several tens of μm or more may be used, and the method of adjusting the surface roughness is not particularly limited.

[Embodiment 1 of Ceramic Sintered Body] Further, the ceramic sintered body constituting the contact portion of the welding end tabs 10 and 11 of this embodiment is composed of a silicon nitride crystal and a grain boundary phase between the silicon nitride crystals. Y ₂ SiAlO ₅ N crystals and an amorphous phase are present, the silicon nitride content is 80% by mass or more, and 2θ = 32 to 33 ° of Y ₂ SiAlO ₅ N in the X-ray diffraction chart. When the peak intensity of the crystal is X, 2θ = 33.2 to 34.2 °, and the peak intensity of the silicon nitride crystal is Y, the ratio X / Y is preferably 0.1 or more and 0.5 or less. is there.

In the case where the above-described configuration is satisfied, the occupancy of the Y ₂ SiAlO ₅ N crystal is increased while the amorphous phase that bonds the silicon nitride crystal is present in the grain boundary phase, and the grain boundary phase is increased. There are fewer voids formed. Thus, when there are few space | gap produced in a grain boundary phase, the mechanical strength of a ceramic sintered compact becomes comparatively high. The portion where the voids generated in the grain boundary phase are densely observed in the ceramic sintered body can be confirmed by magnifying with a microscope or the like, and the portion where the voids are densely packed can be confirmed visually. . For example, when the surface of the ceramic sintered body is observed by magnifying it 100 times, a portion where voids are densely seen appears as white spots (white spots). Further, if the white spot has an equivalent circle diameter of 1 μm or more and 5 μm or less, it appears white even when viewed in an area where there are more than 2200 per 0.15 mm ² .

  In addition, the main component in a ceramic sintered compact means the component which occupies 70 mass% or more with respect to 100 mass% of components which comprise a ceramic sintered compact.

The content of silicon nitride can be determined by an X-ray diffractometer (XRD). Specifically, the content of silicon nitride can be determined by identifying the components constituting the ceramic sintered body by XRD and analyzing the identified components by Rietveld. Further, the ratio X / Y can be obtained from the X-ray diffraction chart obtained by XRD. The presence or absence of silicon nitride crystals and Y ₂ SiAlO ₅ N crystals can be confirmed by identification using XRD or a transmission electron microscope (TEM). Furthermore, the presence of the amorphous phase can be confirmed by the presence or absence of a halo pattern.

In addition to the Y ₂ SiAlO ₅ N crystals, Y ₅ (Si ₄ ) ₃ N (apatite), Y ₂ Si ₂ O ₇ (disilicate), and Y ₂ SiO ₅ are included in the grain boundary phase of the ceramic sintered body. At least one kind of crystal may be present among (monosilicate).

Here, the structure of the ceramic sintered body will be described with reference to the schematic view of FIG. As shown in FIG. 3, the ceramic sintered body has a plurality of columnar silicon nitride crystals 12 without orientation, and a grain boundary phase 13 exists between the silicon nitride crystals 12. The grain boundary phase 13 includes an amorphous phase and a Y ₂ SiAlO ₅ N crystal (not shown). When the Y ₂ SiAlO ₅ N crystals are few in the grain boundary phase, voids are likely to occur.

In particular, the number of white spots having an equivalent circle diameter of 1 μm or more and 5 μm or less on the surface of the ceramic sintered body is preferably 2000 or less per 0.15 mm ² . For example, when the number of white spots having an equivalent circle diameter of 1 μm or more and 5 μm or less is 2000 or less, there are few voids generated in the grain boundary phase, and the mechanical strength can be made relatively high. The surface is the surface that forms the outside of the ceramic sintered body, but the number of white spots can be measured by measuring the surface of the ceramic sintered body as a mirror surface. Good.

Next, a method for measuring the white spot on the surface of the ceramic sintered body will be described. First, the surface of the ceramic sintered body is polished. And after washing | cleaning the mirror surface obtained by grinding | polishing, it observed with 100 time magnification using an optical microscope, and an area was 0.15 mm < ² > (the length of a horizontal direction is 1000 micrometers, the length of a vertical direction is 150 micrometers). A range is photographed in a dark field using a CCD camera attached to an optical microscope, and image data is acquired. By using the obtained image data and performing particle analysis using image analysis software “A image-kun” (registered trademark, manufactured by Asahi Kasei Engineering Co., Ltd.), the equivalent circle diameter and number of white spots can be obtained. As the setting conditions for particle analysis, for example, the brightness is set to light, the binarization method is manually set, the small figure removal area is 1 μm ² , and a threshold value that is an index indicating the brightness of the image is set in the image. The peak value of the histogram indicating the brightness of each point (each pixel) is 1.2 times or less.

Next, an example of the composition of the ceramic sintered body will be described. The ceramic sintered body contains 80% by mass or more of silicon nitride, and examples of components other than silicon nitride include yttrium (Y), aluminum (Al), and silicon (Si). Then, the content of these components, Y is _Y 2 _{O 3} 14 wt% 7 wt% or more in terms of less, Al is _Al 2 _{O 3} 5 wt% or more 2% by mass in terms of less, Si is in terms of SiO ₂ And 0.5 mass% or more and 2 mass% or less.

  Next, an example of a method for measuring the content in the ceramic sintered body will be described. First, the oxygen content in the ceramic sintered body is determined by an infrared absorption method using an oxygen analyzer (EMGA-650FA manufactured by Horiba, Ltd.).

Next, ICP (Inductively Coupled Plasma) emission spectroscopic analyzer (IC manufactured by Shimadzu Corporation)
Quantitative analysis of Y and Al is performed using PS-8100). Then, to convert the quantitative value of the resulting Y and Al by quantitative analysis, each _Y 2 _{O 3} and _Al 2 _{O 3.} Thus, the Y to _Y 2 _{O 3,} it is possible to determine the content when converted to Al to _Al 2 _{O 3.} Next, the amount of oxygen required in terms of this oxide was subtracted from the oxygen content in the ceramic sintered body, and this subtracted amount of oxygen was converted to SiO ₂ , and this value was converted to SiO ₂ . When content.

  In addition to yttrium, aluminum and silicon, the ceramic sintered body may contain chromium, manganese, iron, copper, tungsten, molybdenum, etc., and in particular, any one of chromium, manganese, iron and copper. It is preferable to include a first silicide which is a silicide including one kind.

When each of the silicides of chromium, manganese, iron and copper is included, the ceramic sintered body can be colored with a lower brightness, so that contamination due to welding can be made inconspicuous. Chromium, manganese, as each of the silicide of iron and copper, for example, composition _formula, a component represented as CrSi _2, MnSi _2, FeSi ₂ and CuSi ₂ or the like.

  In addition, it is suitable that content of chromium, manganese, iron, or copper is 0.02 mass% or more and 2 mass% or less among 100 mass% of all the components which comprise a ceramic sintered compact.

Furthermore, it is preferable that the ceramic sintered body of the present embodiment includes a second silicide which is a silicide of tungsten or molybdenum. By containing the second silicide, it is possible to make the ceramic sintered body have a color tone with lower brightness, so that contamination due to welding can be made less noticeable. For example, tungsten or molybdenum silicide is a component whose composition formula is expressed as W ₅ Si ₃ (JCPDS # 81-1916), MoSi ₂ or the like.

  In addition, it is suitable that content of tungsten or molybdenum is 0.02 mass% or more and 2 mass% or less among 100 mass% of the total mass of a ceramic sintered compact.

[Embodiment 2 of Ceramic Sintered Body] The ceramic sintered body constituting the contact portion of the welding end tabs 10 and 11 contains oxides of calcium, aluminum and rare earth elements, and is oxidized of calcium, aluminum and rare earth elements. The total content of calcium and aluminum in 100% by mass of the product is 0.3% to 1.5% by mass, 14.2% to 48.8% by mass in terms of oxides, The remainder is an oxide of a rare earth element, and silicon nitride has a composition formula of Si _6-Z Al _Z O _Z N _8-Z (z = 0.1-1).
It is also preferable that the average crystal grain size is 20 μm or less (excluding 0 μm).

When the above-described configuration is satisfied, the number of crystal grains that have grown abnormally is not small, so the variation in crystal grain size is small, the bulk density of the ceramic sintered body is high, and the rigidity is high. Deformation can be suppressed. Further, even if the temperature of the member to be welded is high, the number of abnormally grown crystal particles is small, so that the strength is hardly lowered and the crystal symmetry of β-Si ₃ N ₄ is hardly impaired, so that heat conduction The rate is not easily lowered, and the thermal shock resistance can be maintained.

Here, the solid solution amount z can be calculated as follows. First, a sample was pulverized until it passed through a mesh having a particle size number of 200, and the obtained powder was subjected to high-purity α-silicon nitride powder (E-product manufactured by Ube Industries) as a sample for correcting the diffraction angle in the powder X-ray diffraction method. 10 grade, aluminum content of 20 mass ppm or less) is added 60 mass% and mixed uniformly in a mortar, the analysis range 2θ is 33-37 ° by the powder X-ray diffraction method, and the scanning step width is The profile intensity is measured at a Cu-Kα line (λ = 1.54056 Å) at 0.002 °. Note that the angle is corrected using the maximum peak value obtained from the angle correction sample. And the difference (Δ2θ ₁ ) between the average 2θ of the top 10 points of the peak intensity obtained every 0.002 ° of α (102) appearing in the vicinity of 2θ = 34.565 ° (Δ2θ ₁ ), and 2θ = 35 The difference (Δ2θ ₂ ) between the average 2θ of the top 10 peak intensities obtained every 0.002 ° of α (210) appearing near .333 ° and Δ35.333 ° (Δ2θ ₂ ) is obtained, respectively, Let ₁ + Δ2θ ₂ ) / 2 be the correction Δ2θ.

Next, the angle obtained by correcting the average 2θ of the top 10 points of the peak intensity obtained every 0.002 ° of β (210) appearing in the vicinity of 2θ = 36.055 ° by the correction Δ2θ is the peak of β (210) of the sample. Let it be the position (2θ _β ). Then, the lattice constant a (Å) is calculated by substituting the lattice constant in the peak position (2θ _β ), λ = 1.54056Å, (hkl) = (210), c = c-axis direction into the following equation. sin ² θ _β = λ ² (h ² + hk + k ² ) / (3a ² ) + λ ² l ² / (4c ² ) The lattice constant a (Å) calculated by this equation, H. Jack, J.M. Mater. Sci. 11 (1976) 1135-1158, FIG. From the graph of lattice constant a (Å) −solid solution amount z described in FIG. 13, the solid solution amount z can be obtained. In particular, the solid solution amount z is more preferably from 0.35 to 0.70.

  The average crystal grain size of silicon nitride is obtained from an image obtained by photographing a fracture surface of a ceramic sintered body in accordance with JIS R 1670-2006, using a scanning electron microscope, with a magnification of, for example, 2000 to 4000 times. be able to.

  [Embodiment 3 of Ceramic Sintered Body] Further, the ceramic sintered body constituting the contact portion of the welding end tabs 10 and 11 contains gehlenite in the grain boundary phase, and has a diffraction angle of 31 obtained by the X-ray diffraction method. It is also preferable that the half-value width of the peak intensity of gehlenite at ˜32 ° is 0.5 ° or less. When gehlenite is included in the grain boundary phase, the amorphous phase that is easily corroded by an acid or alkali component in the grain boundary phase is relatively reduced, so that the mechanical strength can be maintained higher. In addition, since the amorphous phase is relatively less in the grain boundary phase, it becomes more difficult to deform even when exposed to high temperatures.

And when the half value width of the peak intensity of gehlenite at a diffraction angle of 31 ° to 32 ° obtained by the X-ray diffraction method is 0.5 ° or less, the distortion of gehlenite crystals becomes small, and the ceramic sintered body Both thermal conductivity and rigidity can be increased. The composition formula of Gehlenite, for _example, are shown as Ca ₂ Al ₂ SiO _7, it is not limited to the stoichiometric composition. Moreover, it is suitable for the ceramic sintered body that magnesium and sodium are dissolved in gehlenite. When magnesium and sodium are dissolved in gehlenite, the abundance of crystals (gehlenite) in the grain boundary phase is increased, and the abundance ratio of the amorphous phase is reduced, so that deformation of the grain boundary phase is suppressed, The rigidity of the ceramic sintered body can be increased.

The composition formula of gehlenite magnesium and sodium are dissolved in, for _{example, ((Ca 1- (a +} b), Na a, Mg b) 2 (Al 1- (c + d), Si c, Mg d) 2 _{(Si 1- (e + f)} , Al e, Mg f) O 7) ( where it can be expressed as 0 <a + b <1,0 < c + d <1,0 <e + f <1). Further, the presence of gehlenite in the grain boundary phase of the ceramic sintered body can be confirmed using XRD. The solid solution of magnesium and sodium in gehlenite should be confirmed using a transmission electron microscope (TEM) equipped with an energy dispersive X-ray spectrometer (EDS) or a wavelength dispersive X-ray spectrometer (WDS). Can do.

  [Embodiment 3 of Ceramic Sintered Body] The ceramic sintered body constituting the contact portion of the welding end tabs 10 and 11 has a contact surface containing carbon, and the content thereof is 40 atomic% or more. Preferably it is. Since the electrical conductivity in the contact surface is increased and the arc can be generated stably, the occurrence of welding defects can be suppressed. The carbon content in the contact surface of the contact portion can be measured using an X-ray photoelectron spectrometer.

  [Embodiment 4 of Ceramic Sintered Body] Further, in the ceramic sintered body constituting the contact portion of the welding end tabs 10, 11, the contact surface of the contact portion contains boron nitride, and the content thereof is 3% by mass or more. It is suitable that it is 20 mass% or less. When the above-described configuration is satisfied, the contact surface can be a dense surface, and the glass component is less likely to adhere due to the high adhesion preventing action of boron nitride. The crystal structure of boron nitride is preferably rhombohedral.

  Here, boron nitride has a hexagonal crystal and a rhombohedral crystal as a crystal structure at normal pressure, and rhombohedral boron nitride is a nitride having a c-axis lattice constant (1.000 nm) in a unit cell of hexagonal crystal. It is larger than the lattice constant (0.66813 nm) on the c-axis of the boron unit cell.

  And, since the crystal structure of boron nitride is rhombohedral, a part of the unit cell constituting the columnar crystal particles of silicon nitride penetrates into the unit cell of rhombohedral boron nitride at the time of sintering, It is considered that the rhombohedral boron nitride and silicon nitride are firmly bonded, and the bonded crystal has a complicated shape, so that the bonding force is increased.

  Here, the content of each component in the contact surface is determined by using the X-ray diffractometer (XRD) to identify the component in the contact surface, and then using the X-ray fluorescence analyzer (XRF). What is necessary is just to obtain | require quantity and to convert into content of the identified component. Alternatively, the polishing powder obtained by polishing the contact surface in the depth direction to a depth of about 30 μm to 50 μm was used as a sample, and the content of the element was determined by using an ICP emission spectrometer (ICP). You may convert into content of a component.

  When the rhombohedral only boron nitride is identified when measured using XRD, the boron nitride content obtained by the above-described method is the rhombohedral boron nitride content. When hexagonal and rhombohedral boron nitride has been identified, a polishing powder obtained by polishing from the contact surface to a depth of about 30 μm to 50 μm as a sample is used as a sample. The mass percentage of each crystal structure may be obtained by the belt method, and the boron nitride content may be calculated by multiplying the rhombohedral mass percentage.

  Next, an example of the manufacturing method of the welding end tab of this embodiment is demonstrated.

[Manufacturing Method of First Embodiment of Ceramic Sintered Body] First, as a first starting material, silicon powder (average particle diameter D ₅₀ = 0.5 to ₁₀₀ μm) and silicon nitride powder (α conversion 50) %, Average particle diameter D ₅₀ = 0.5 to 10 μm), and as a sintering aid, yttrium oxide powder (average particle diameter D ₅₀ = 0.5 to 10 μm) and aluminum oxide powder (average particle diameter D) ₅₀ = 0.5-10 μm). Then, each powder of the first starting material and the sintering aid is mixed to produce a mixed powder. The mass ratio of the silicon powder to the silicon nitride powder is 80:20 to 90:10.

  And each powder of yttrium oxide, aluminum oxide, and silicon dioxide is 10.2 mass% or more and 20 mass% or less of the powder of yttrium oxide, and 2.9 mass of the powder of aluminum oxide among the total 100 mass% of the mixed powder. % To 7.3% by mass or less.

  Moreover, in order to obtain the ceramic sintered compact containing the 1st silicide which is a silicide containing at least any 1 type of chromium, manganese, iron, and copper, chromium oxide, manganese oxide, ferric oxide, and copper oxide are obtained. Any one of these powders may be appropriately weighed and added to the mixed powder together with the sintering aid. The added chromium oxide, manganese oxide, ferric oxide and copper oxide powder reacts with silicon during firing, desorbs oxygen, and becomes a thermodynamically stable silicide. A low color tone can be obtained.

  Further, in order to obtain a ceramic sintered body containing a second silicide which is a silicide of tungsten or molybdenum, a powder of tungsten oxide or molybdenum oxide may be appropriately weighed and added to the mixed powder together with a sintering aid. . The added tungsten oxide or molybdenum oxide powder reacts with silicon during firing, desorbs oxygen, and exists in the grain boundary phase as silicide.

  Then, powders such as mixed powder and sintering aid are put together with various binders such as polyvinyl alcohol (PVA) and polyethylene glycol (PEG), for example, barrel mill, rotary mill, vibration mill, bead mill, sand mill or agitator mill. Mix and pulverize by wet to make slurry. Furthermore, you may add a thickening stabilizer, a dispersing agent, a pH adjuster, an antifoamer, etc. In order to obtain a welding end tab in which the contact surface of the contact portion contains carbon and the content thereof is 40 atomic% or more, the ceramic sintered body may be added with a pH adjusting agent containing sodium.

  Next, the slurry is spray-dried into granules by using a spray-drying apparatus.

  Then, the granules are filled in a mold and pressed using a uniaxial pressing method to obtain a molded body having a predetermined shape.

  Next, the molded body is degreased in a nitrogen atmosphere or a vacuum atmosphere, for example, at a holding time of 15 hours to 48 hours to obtain a degreased body. In addition, although the degreasing temperature at this time changes with kinds of the added binder, 900 degreeC or less is good, and it is especially preferable to set it as 400 degreeC or more and 800 degrees C or less.

  Next, this degreased body is nitrided at a temperature of 1000 ° C. to 1400 ° C. at a nitrogen partial pressure of 50 kPa to 1.1 MPa to obtain a nitride.

The nitride is fired by holding it at a nitrogen partial pressure of 50 kPa to 300 kPa at a temperature of 1640 ° C. or more and less than 1800 ° C. for 10 to 15 hours, and then left to cool to room temperature, thereby being used for welding according to this embodiment. You can get an end tab. In addition, in order to obtain a welding end tab made of a ceramic sintered body having a ratio X / Y of 0.1 or more and 0.5 or less, the welding obtained by the above-described method in a hermetic firing vessel made of silicon nitride. An end tab is mounted, heat-treated in a nitrogen atmosphere at a temperature of 1750 ° C. to 1900 ° C., cooled at a rate of temperature decrease from the maximum temperature of 800 ° C. to 10 ° C./min to 11.2 ° C./min, and then released to room temperature. It can be obtained by cooling.

Further, in order to obtain a welding end tab made of a ceramic sintered body in which the number of white spots having a circle-equivalent diameter of 1 μm or more and 5 μm or less on the surface is 2000 or less per 0.15 mm ² , welding to the unit volume of the firing container is performed. The mass of the end tab for use may be 0.4 g / cm ³ or less.

  Examples of the present invention will be specifically described below, but the present invention is not limited to these examples.

[Method for Manufacturing Second Embodiment of Ceramic Sintered Body] In order to obtain the second embodiment of the ceramic sintered body, the second starting material may be used instead of the first starting material. As a second starting material, a silicon nitride powder represented by a composition formula of Si _6-Z Al _Z O _Z N _8-Z and having a solid solution amount z of 0.5 or less (alpha conversion ratio of 50% or more, (Average particle diameter D ₅₀ = 0.5 to 4 μm) and powders of calcium oxide, aluminum oxide, and rare earth element oxide are prepared as sintering aids. The composition formula _{Si 6-Z Al Z O Z} N 8-Z to obtain the crystals of silicon nitride is that represented by β- SiAlON by (z = 0.1 to 1), solid solution amount z is 0 A silicon nitride powder of .05 or more and 0.5 or less may be used.

  Here, the sum of the powders of calcium oxide, aluminum oxide and rare earth element oxides, which are sintering aids, is the sum of the silicon nitride powder and the sum of these sintering aid powders being 100% by mass. In some cases, the content may be 3% by mass or more and 19.2% by mass or less, and the content of each sintering aid is 100% by mass with respect to the total of 100% by mass of the oxides of calcium oxide, aluminum oxide, and rare earth elements. Thus, the content of calcium oxide and aluminum oxide may be 0.3% by mass or more and 1.5% by mass or less, 14.2% by mass or more and 48.8% by mass or less, and the balance may be an oxide of a rare earth element.

  These mixed powders and powders such as sintering aids are wetted together with various binders such as polyvinyl alcohol (PVA) and polyethylene glycol (PEG), for example, barrel mill, rotary mill, vibration mill, bead mill, sand mill or agitator mill. The slurry can be mixed and pulverized to obtain a slurry, which can be manufactured through the same steps as in the manufacturing method of the first embodiment.

[Method for Producing Third Embodiment of Ceramic Sintered Body] In order to obtain the third embodiment of the ceramic sintered body, the third starting material is used instead of the first starting material and the second starting material. May be used. As a third starting material, first, a metal silicon powder and a silicon nitride powder having a β conversion rate of 20% or less are prepared, and a mass ratio of (metal silicon powder) / (silicon nitride powder) Is mixed so as to be 1 or more and 10 or less to obtain a first powder. Here, depending on the particle size of the metal silicon powder, there is a risk of insufficient nitriding and insufficient sintering. Therefore, the metal silicon powder is cumulative when the total volume of the particle size distribution curve is 100%. A particle diameter (D ₉₀ ) with a volume of 90% is 10 μm or less, preferably 6 μm or less.

  Further, a second powder obtained by weighing magnesium aluminate powder and metal compound powder is obtained as a sintering aid.

  The first powder and the second powder are powders weighed so that the second powder is 10% by mass to 23% by mass when the total of the first powder and the second powder is 100% by mass. Use as starting material. The metal compound is aluminum oxide, silicon dioxide, calcium carbonate, or the like. Moreover, you may use powders, such as magnesium hydroxide, magnesium oxide, and magnesium carbonate, instead of the powder of magnesium aluminate. These mixed powders and powders such as sintering aids are wetted together with various binders such as polyvinyl alcohol (PVA) and polyethylene glycol (PEG), for example, barrel mill, rotary mill, vibration mill, bead mill, sand mill or agitator mill. The slurry can be mixed and pulverized to obtain a slurry, which can be manufactured through the same steps as in the manufacturing method of the first embodiment.

  [Manufacturing Method of Ceramic Sintered Body According to Fourth Embodiment] To obtain the fourth embodiment of the ceramic sintered body, the first starting material, the first The paste obtained by adding the starting material 2 or the third starting material and rhombohedral boron nitride powder to a solvent such as ethanol together with a binder is applied by screen printing, and the temperature is set to, for example, 60 ° C. or more and 100 ° C. What is necessary is just to perform the process made to dry below ℃. By this step, a silicon nitride-based molded body having rhombohedral boron nitride on the surface is obtained. Note that the amount of rhombohedral boron nitride powder added may be 3% by mass or more and 20% by mass or less in the total of 100% by mass of the above powders.

Alternatively, instead of the above method, a silicon nitride-based molded body is arranged at a predetermined position in the reaction vessel, and boron source gas is BCl ₃ , BF ₃ , BBr ₃ , B ₂ H ₆ , B ₃ N ₃ H ₃ , B _{At least one of 3} N ₃ H ₃ C ₁₃ and B (C ₂ H ₅ ) ₃ , and HN ₃ , NH ₃ , N ₂ H ₂ , NH ₄ Cl, NH ₄ Br, NH as a nitrogen source gas _At least one of ₄ F, NH ₄ Hf _2, and NH ₄ I and at least one of Ar, He, and H ₂ are introduced into the reaction vessel as a diluted carrier gas (carrier gas). The vapor phase synthesis may be performed at a temperature of 600 to 800 ° C. and for a time of 1 to 3 hours. By this vapor phase synthesis, it is possible to obtain a silicon nitride-based molded body in which silicon nitride particles and boron nitride particles are mixed on the surface.

The first embodiment will be described. First, silicon powder (average particle size D ₅₀ = 10 μm) and silicon nitride powder (α conversion 90%, average particle size D ₅₀ = 1 μm) as starting materials, and yttrium oxide powder as a sintering aid (Average particle diameter D ₅₀ = 1 μm), aluminum oxide powder (average particle diameter D ₅₀ = 1 μm) and silicon dioxide powder (average particle diameter D ₅₀ = 1)
μm) were prepared, and each powder of the starting material and the sintering aid was mixed to prepare a mixed powder. The mass ratio of the silicon powder to the silicon nitride powder was 84:16, and each of the yttrium oxide, aluminum oxide, and silicon dioxide powders was 13.3% of the total 100 mass% of the mixed powder. 8% by mass and aluminum oxide powder were weighed to 3.7% by mass.

  Furthermore, 1.4 parts by mass of ferric oxide powder and 0.7 parts by mass of tungsten oxide powder were weighed and added to 100 parts by mass of the mixed powder.

  Then, grinding media composed of the respective powders, PVA, water and silicon nitride were put in a barrel mill and mixed and pulverized in a wet manner to obtain a slurry.

  The slurry was then granulated by spray drying using a spray dryer.

  The granules were filled in a mold and pressed using a uniaxial pressing method to obtain a molded body having a predetermined shape.

  Next, degreasing was carried out by holding for 20 hours in a nitrogen atmosphere at 600 ° C. to obtain a degreased body. Thereafter, the degreased body was placed in a firing furnace in which a graphite resistance heating element was installed, and nitrided at a temperature of 1300 ° C. at a nitrogen partial pressure of 120 kPa, thereby obtaining a nitride. The obtained nitride was held at a nitrogen partial pressure of 200 kPa and a firing temperature of 1750 ° C. for 10 hours, and then allowed to cool to room temperature, whereby sample No. which was an end tab for welding was used. 1 was obtained.

In addition to the above sample, as a comparative example, a sample No. 1 which is a welding end tab made of a ceramic sintered body of the main component shown in Table 1 was used. 2 and 3 were produced.
Here, the components constituting the ceramic sintered body of each sample were identified by XRD, the principal component was determined by Rietveld analysis of the identified components, and the principal components are shown in Table 1.

  And as shown in FIG. 2, the end surface of the 4th metal member 5 whose thickness is 25 mm was welded to one main surface of the 3rd metal member 4 by the carbon dioxide arc welding method. For welding, main welding and finish welding were sequentially performed using a welding wire for low current thin plate as a welding material. In the main welding, the current was 300 A and the voltage was 38 V, and in finish welding, the current was 250 A and the voltage was 32 V. And the end tab for welding was removed after completion | finish of welding.

  When removing the welding end tab, the evaluation in Table 1 is 1 for a sample that can be easily removed by hand, and 2 for a sample that cannot be removed by hand and can be removed by hitting with a hammer. Fill in the column. In addition, in the sample in which 1 was entered in the evaluation column of Table 1, no omission was observed in the contact portion that abuts on the member to be welded, and in the sample in which 2 was entered, partial omission was observed in the contact portion.

  As shown in Table 1, sample no. 1 has at least a contact portion that comes into contact with a member to be welded made of a ceramic sintered body containing silicon nitride as a main component. Therefore, the wettability with respect to molten metal is smaller than that of sample Nos. 2 and 3; Can do. In addition, sintered ceramics mainly composed of silicon nitride have high mechanical strength and high corrosion resistance against molten metal, so there is little change in shape and strength due to repeated use, and there are many times that can be used repeatedly (durability). High).

  By the same method as shown in Example 1, a welding end tab made of a ceramic sintered body containing silicon nitride as a main component was produced.

Next, an end tab for welding was placed in a closed type firing vessel made of silicon nitride, heat-treated at a temperature of 1750 ° C. in a nitrogen atmosphere, and then cooled to 800 ° C. at a temperature lowering rate shown in Table 2. The end tab for welding was obtained by standing to cool. The mass of the ceramic sintered body with respect to the volume of the firing container was set to 0.5 g / cm ³ .

Next, each sample was measured by XRD, and the silicon nitride content and the crystal were identified. As a result, in each sample, the silicon nitride content was 80% by mass or more, and it was confirmed that the silicon nitride crystal and the crystal having the composition formula Y ₂ SiAlO ₅ N were confirmed. Moreover, since a halo pattern was observed, it was confirmed that an amorphous phase was present.

Further, from the X-ray diffraction chart of each sample obtained, the peak intensity X of the Y ₂ SiAlO ₅ N crystal at 2θ = 32 to 33 ° and the silicon nitride crystal 12 at 2θ = 33.2 to 34.2 ° The ratio X / Y with the peak intensity Y was calculated, and the value is shown in Table 2.

  Next, the surface of each sample was visually observed to confirm the presence or absence of a white portion. The results are shown in Table 3.

Further, after polishing the surface of each sample and washing the mirror surface obtained by polishing, the surface was observed with an optical microscope at a magnification of 100 times, and the area was 0.15 mm ² (the horizontal length was 1000 μm, the vertical length was The image was obtained by capturing a dark field image taken with a CCD camera over a range with a direction length of 150 μm), and by analyzing the particles using image analysis software “A Image-kun” (registered trademark, manufactured by Asahi Kasei Engineering Corp.). Table 2 shows the number of white spots having an equivalent circle diameter of 1 μm to 5 μm. Here, as the setting conditions for particle analysis, the brightness is set to light, the binarization method is manually set, the small figure removal area is 1 μm ² , and the threshold value which is an index indicating the brightness of the image is set in the image. The peak value of the histogram indicating the brightness of each point (each pixel) was 1.1 times.

  Next, a test piece is prepared by the same method as that used to prepare each sample, and the four-point bending strength is conformed to JIS R 1601-2008, and the relative method defined by JIS R 1648-2002 is also conformed. Thus, the thermal shock temperature was determined, and the values are shown in Table 2.

As shown in Table 2, sample no. Nos. 6 to 14 include silicon nitride crystals and Y ₂ SiAlO ₅ N crystals and an amorphous phase in the grain boundary phase between the silicon nitride crystals, and the silicon nitride content is 80% by mass or more. Yes, since the ratio X / Y is 0.1 or more and 0.5 or less, there is no portion that looks white. That is, sample no. Nos. 6 to 14 were found to have relatively few voids in the grain boundary phase, and had both excellent mechanical strength and high thermal shock resistance.

1: 1st metal member 2: 2nd metal member 3: 3rd metal member 4: 4th metal member 5: Wire for clamping 6: Back metal 10, 11: End tab for welding 12: Crystal of silicon nitride 13: Grain Minister

Claims (8)

  An end tab for welding, wherein at least a contact portion in contact with a member to be welded is made of a ceramic sintered body mainly composed of silicon nitride. The ceramic sintered body includes silicon nitride crystals, Y ₂ SiAlO ₅ N crystals and an amorphous phase in the grain boundary phase between the silicon nitride crystals, and the silicon nitride content is 80 The peak intensity of the Y ₂ SiAlO ₅ N crystal at 2θ = 32 to 33 ° in the X-ray diffraction chart is X% or more, and the peak intensity of the silicon nitride crystal at 2θ = 33.2 to 34.2 ° 2. The welding end tab according to claim 1, wherein when the peak intensity is Y, the ratio X / Y is 0.1 or more and 0.5 or less. 3. The end tab for welding according to claim 1, wherein the number of white spots having an equivalent circle diameter of 1 μm to 5 μm on the surface of the ceramic sintered body is 2000 or less per 0.15 mm ^2. . The ceramic sintered body contains calcium, aluminum and rare earth element oxides, and the total content of calcium and aluminum in 100% by mass of calcium, aluminum and rare earth element oxides is 0 in terms of oxides. 3 mass% or more and 1.5 mass% or less, 14.2 mass% or more and 48.8 mass% or less, and the balance is an oxide of a rare earth element, and silicon nitride has a composition formula of Si _6-Z Al _{Z O Z N 8-Z (} z = 0.1~1) in a represented β- sialon claim, wherein the average crystal grain size of 20μm or less (excluding 0 .mu.m.) The end tab for welding according to 1.   The ceramic sintered body contains gehlenite and is obtained by an X-ray diffraction method, and the half-value width of gehlenite peak intensity at a diffraction angle of 31 ° to 32 ° is 0.5 ° or less. The end tab for welding according to 1.   2. The end tab for welding according to claim 1, wherein the ceramic sintered body has a contact surface of the contact portion containing carbon and a content of 40 atomic% or more.   7. The ceramic sintered body according to claim 1, wherein the contact surface of the contact portion contains boron nitride, and the content thereof is 3 mass% or more and 20 mass% or less. End tab for welding as described in 1.   8. The welding end tab according to claim 7, wherein the boron nitride has a rhombohedral crystal structure.