JP2016144829A - 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: Preferably, in an end tab for welding, at least a contact part arranged in the state of facing a member to be welded is made of a ceramic sintered body predominantly composed of silicon nitride. In addition, preferably, an opposed surface of the contact part has an open blowhole, and a plurality of columnar crystals of silicon nitride are positioned within the open blowhole in such a manner as to cross one another.SELECTED DRAWING: Figure 1

Description

  The present disclosure relates to a welding end tab.

  Conventionally, when welding the members to be welded together, the relative positions of the members to be welded are fixed, and in order to suppress a molten metal dripping caused by welding, End tabs are used. Conventionally, steel welding end tabs have been used, but steel welding end tabs must be preliminarily fixed to the member to be welded by welding in advance, which is cumbersome and ends the welding. The subsequent cutting work took time and effort.

For example, Patent Document 1 proposes a welding end tab made of a solid flux or a high melting point ceramic, and uses a ceramic such as cordierite or steatite, or a flux of SiO ₂ —MnO—CaO. Have been described.

JP 61-119398 A

  However, even if the welding end tab proposed in Patent Document 1 is formed of any component, it is easy to wet the molten metal, so that the molten metal easily adheres to both the welded portion and the welding end tab. It was. When such adhesion occurs, the welding end tab and the joined portion are joined, and an extra step such as a step of cutting the adhesion portion is required 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, wherein at least a contact portion arranged to face a member to be welded is made of a ceramic sintered body mainly composed of silicon nitride.

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

It is a perspective view which shows an example of the welding operation | work using the welding end tab of this embodiment. It is a perspective view which shows the other example of the welding operation | work using the end tab for welding. It is the microscope picture which expanded the open pore in the opposing surface 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 operation using the welding end tab of the present embodiment. The welding end tab 10 of the example shown in FIG. 1 is used for welding respective end faces of the first metal member 1 and the second metal member 2 which are members to be welded. In the example shown in FIG. 1, all the members to be welded are plate-shaped, but the shape of the members to be welded is not limited to this.

  The welding end tab 10 of this embodiment is used for fixing the relative position of the member to be welded and preventing leakage of molten metal to the outside during welding. In the example shown in FIG. 1, two welding end tabs 10 are arranged. The two end tabs 10 for welding are arrange | positioned in the part to which the end surface of the 1st metal member 1 and the end surface of the 2nd metal member 2 are welded. The two welding end tabs 10 are fixed to the side surfaces of the first metal member 1 and the second metal member 2 in a state where they are pressed by the clamping wire 5. Thus, the welding end tab 10 has a contact portion with the member to be welded, and the contact portion has a facing surface 10a that faces and contacts the side surfaces of the first metal member 11 and the second metal member 2. ing.

  FIG. 2 is a perspective view showing another example of a state of welding work using the welding end tab 10 of the present embodiment. In the example shown in FIG. 2, the welding end tab 10 is used to weld the end surface of the fourth metal member 4 that is the member to be welded to one main surface of the third metal member 3 that is the member to be welded. The fourth metal member 4 is supported by a backing metal 6 temporarily fixed to the third metal member 3.

  The welding end tab 10 is formed of a ceramic sintered body (hereinafter, also simply referred to as a ceramic sintered body) in which at least a contact portion disposed to face a member to be welded has silicon nitride as a main component. The welding end tab 10 of the present embodiment has a contact portion made of a ceramic sintered body. Therefore, the facing surface 10a of the contact portion is also made of a ceramic sintered body. The entire welding end tab 10 may be made of a ceramic sintered body. And the main component in a ceramic sintered compact means the component which occupies 70 mass% or more among 100 mass% of components which comprise a ceramic sintered compact, and it is suitable that it is especially 80 mass% or more.

  In the following description, the entire welding end tab 10 is described as being made of a ceramic sintered body. Since the ceramic sintered body constituting the welding end tab 10 of the present embodiment is difficult to wet with the molten metal, the molten metal hardly adheres to the welding end tab 10, and the welding end tab 10 and the joined portion are joined. It is hard to be done. For this reason, the welding end tab 10 can be peeled off with a relatively small force without performing an extra costly step such as a step of cutting the adhesive portion to remove the welding end tab 10. Moreover, the ceramic sintered body has high mechanical strength, and changes in shape and strength due to repeated use are small. Further, the welding end tab 10 made of a ceramic sintered body has higher corrosion resistance to molten metal than a steel welding end tab. The welding end tab 10 of the present embodiment made of a ceramic sintered body has a small change in shape and strength due to repeated use, and can be used repeatedly (high durability).

  FIG. 3 is an enlarged micrograph of the vicinity of the facing surface 10a of the welding end tab 10 of the present embodiment. The welding end tab 10 may have open pores 9 on the facing surface 10a of the contact portion, and a plurality of silicon nitride columnar crystals 7 may be located inside the open pores 9 so as to cross each other.

In the ceramic sintered body, the columnar crystal 7 of silicon nitride is more difficult to wet with the molten metal than the grain boundary phase 8. Therefore, when the silicon nitride columnar crystal 7 has a plurality of open pores 9 intersecting each other on the opposing surface 10a, the grain boundary phase 8 existing inside the open pores 9 is covered with the columnar crystal, Since there are many areas in the facing surface 10a that are difficult to wet with the molten metal, the molten metal is less likely to adhere to the welding end tab 10, and the welding end tab 10 and the joined portion are less likely to be joined.

  Next, an example of a composition of the ceramic sintered body which comprises the contact part of the welding end tab 10 of this embodiment is demonstrated. This ceramic sintered body is mainly composed of silicon nitride, and examples of components contained in addition to silicon nitride include yttrium, aluminum, and silicon.

  The ceramic sintered body may contain chromium, manganese, iron, copper, tungsten, molybdenum, etc. in addition to yttrium, aluminum, and silicon, and in particular, any one of chromium, manganese, iron, and copper. It is preferable to contain the 1st silicide which is a silicide containing.

When the above-mentioned first silicide is included, the ceramic sintered body can be made to have a lighter color tone, so that contamination due to welding can be made inconspicuous. The first silicide, for example, composition _formula, a component represented as CrSi _2, MnSi _2, FeSi ₂ and CuSi ₂ or the like. In addition, content of chromium, manganese, iron, or copper which comprises a 1st silicide is 0.02 mass% or more and 2 mass% or less among 100 mass% of all the components which comprise a ceramic sintered compact. Is preferred.

It is also preferable that the ceramic sintered body 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.

  The first silicide and the second silicide can be identified by an X-ray diffractometer (XRD). Moreover, about each content of these silicides, what is necessary is just to convert each said element obtained by the fluorescent X ray analyzer (XRF) or the ICP (Inductively Coupled Plasma) emission analyzer (ICP) into the silicide.

  Moreover, it is suitable that the opposing surface 10a contains carbon, and the content is 40 atomic% or more. In this case, the electrical conductivity in the facing surface 10a is increased and an arc can be generated stably, so that the occurrence of welding defects can be suppressed. The carbon content in the facing surface 10a can be measured using an X-ray photoelectron spectrometer. Moreover, when the opposing surface 10a contains carbon, it is suitable that the content is 70 atomic% or less.

  In order to lower the wettability to the molten metal, it is preferable that the surface roughness of the facing surface 10a of the ceramic sintered body is larger. In order to further lower the wettability with respect to the molten metal, it is preferable that the arithmetic average roughness (Ra) of the facing surface 10a of the ceramic sintered body is, for example, about 1 to 50 μm.

  As a method of increasing the surface roughness of the welding end tab 10 made of a ceramic sintered body, when forming a powder containing silicon nitride as a main component into a desired shape, a so-called pressing and pressing surface side of the mold is so-called. By applying discharge texture processing, the transfer surface can be adjusted to an appropriate surface roughness, and when sintering ceramic molded bodies, a relatively rough powder is placed on the shelf board to achieve an appropriate surface roughness. An adjustment method or the like may be used. Further, a method of adjusting the surface roughness by performing blasting using relatively coarse abrasive grains may be used, and the method of adjusting the surface roughness is not particularly limited.

[Embodiment 1 of Ceramic Sintered Body] The ceramic sintered body constituting the contact portion of the welding end tab 10 of this embodiment has Y ₂ SiAlO ₅ N in the grain boundary phase 8 and the silicon nitride content. The peak intensity of Y ₂ SiAlO ₅ N at 2θ = 32 to 33 ° in the X-ray diffraction chart is X and the peak intensity of silicon nitride at 2θ = 33.2 to 34.2 ° is Y In this case, it is also preferable that the ratio X / Y is 0.1 or more and 0.5 or less.

When the above-described configuration is satisfied, the occupancy ratio of Y ₂ SiAlO ₅ N is increased while an amorphous phase that bonds silicon nitride crystals is present in the grain boundary phase 8, and the grain boundary phase 8 There are fewer voids formed. Thus, when there are few voids generated in the grain boundary phase 8, the mechanical strength of the ceramic sintered body becomes relatively high. The portion where the voids generated in the grain boundary phase 8 are densely observed in the ceramic sintered body can be confirmed by magnifying and observing with a microscope or the like, and the portion where the voids are densely packed densely can also be visually confirmed. I can confirm. 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 .

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. Silicon nitride and Y ₂ SiAlO ₅ N can be identified using XRD or transmission electron microscope (TEM). Furthermore, the amorphous phase can be confirmed by the presence or absence of a halo pattern.

In addition to Y ₂ SiAlO ₅ N, Y ₅ (Si ₄ ) ₃ N (apatite), Y ₂ Si ₂ O ₇ (disilicate), and Y ₂ SiO ₅ ( At least one of monosilicate) may be present.

Here, the structure of the ceramic sintered body will be described with reference to the schematic view of FIG. As shown in FIG. 4, the ceramic sintered body has a plurality of silicon nitride columnar crystals 7 without being oriented, and a grain boundary phase 8 exists between the silicon nitride columnar crystals 7. The grain boundary phase 8 includes an amorphous phase and Y ₂ SiAlO ₅ N (not shown). When the grain boundary phase 8 has a small amount of Y ₂ SiAlO ₅ N, 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 facing surface 10a 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 8 and the mechanical strength can be made relatively high. In addition, what is necessary is just to measure the mirror surface obtained by grind | polishing the opposing surface 10a of a ceramic sintered compact for the measurement of the number of white spots.

Next, a method for measuring the white spot on the facing surface 10a of the ceramic sintered body will be described. First, the facing surface 10a 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 of each component 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, quantitative analysis of Y and Al is performed using ICP. 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.

[Embodiment 2 of Ceramic Sintered Body] The ceramic sintered body constituting the contact portion of the welding end tab 10 includes oxides of calcium, aluminum, and rare earth elements, and includes oxides of calcium, aluminum, and rare earth elements. Of the total 100% by mass, the content of calcium converted to oxide is 0.3% by mass to 1.5% by mass, and the content of aluminum converted to oxide is 14.2% by mass to 48.8% by mass. %, And the remainder is an oxide of a rare earth element, and silicon nitride has a composition formula of β − represented by Si _{6 -Z} Al _Z O _Z N ₈ -Z (z = 0.1-1). A sialon having an average crystal grain size of 20 μm or less (excluding 0 μm) is also suitable.

When the above-described configuration is satisfied, there are few abnormally grown crystal grains, so the variation in crystal grain size is small, and the bulk density of the ceramic sintered body is high and the rigidity is high. 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 mechanical strength is hardly lowered and the crystal symmetry of β-Si ₃ N ₄ is hardly impaired. Thermal conductivity is unlikely to decrease, and 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.

  Further, the average crystal grain size of silicon nitride is based on JIS R 1670-2006, and a surface obtained by breaking and polishing a ceramic sintered body with a scanning electron microscope at a magnification of 2000 to 4000 times, for example. Can be obtained from the obtained image.

  [Embodiment 3 of Ceramic Sintered Body] Further, the ceramic sintered body constituting the contact portion of the welding end tab 10 includes gehlenite in the grain boundary phase 8, and at 2θ = 31 ° to 32 ° in the X-ray diffraction chart. It is also preferable that the half width of the peak intensity of gehlenite is 0.5 ° or less. If the grain boundary phase 8 contains gehlenite, the amorphous phase that is easily corroded by an acid or alkali component in the grain boundary phase 8 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 8, it is more difficult to be deformed even when exposed to high temperatures.

And when the half-value width of the peak intensity of gehlenite at 2θ = 31 ° to 32 ° in the X-ray diffraction chart is 0.5 ° or less, the distortion of gehlenite crystals is reduced, and the thermal conductivity of the ceramic sintered body is reduced. Both 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 in solid solution in gehlenite, the presence of crystals (gehlenite) in the grain boundary phase 8 is increased and the abundance ratio of the amorphous phase is lowered, so that deformation of the grain boundary phase 8 is suppressed. Thus, 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 8 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 4 of Ceramic Sintered Body] The ceramic sintered body constituting the welding end tab 10 includes rare earth elements, magnesium and aluminum oxides, and the aluminum content is 0 in terms of oxides. It is preferable that the amount is not more than 6% by mass (excluding 0% by mass).

If the ceramic sintered body contains oxides of rare earth elements, magnesium and aluminum, this oxide can act as a sintering aid to enhance the mechanical properties of the ceramic sintered body, When the content is 0.6% by mass or less (excluding 0% by mass), the corrosion resistance of the ceramic sintered body to acid can be increased, and thus a lot of acid slag is generated during welding. Can be suitably used over a long period of time.

  Further, the ceramic sintered body includes rare earth elements, oxides of magnesium and aluminum, and the oxides of magnesium and aluminum may be magnesium aluminate. With such a configuration, the mechanical properties of the ceramic sintered body can be enhanced, and the corrosion resistance of the ceramic sintered body against alkali can be enhanced. Therefore, when a lot of basic slag is generated during welding. Can be suitably used over a long period of time.

  The oxide content of rare earth elements, magnesium and aluminum is converted to oxide from the content of each element obtained by XRF (Inductively Coupled Plasma) emission analyzer (ICP). do it.

The grain boundary phase 8 preferably contains at least one of RESiO ₂ N, RE ₂ Si ₃ O ₃ N ₄ , RE ₄ Si ₂ O ₇ N ₂ and RE ₅ Si ₃ O ₁₂ N (RE: rare earth element). It is.

  When these silicon oxynitrides are contained in the grain boundary phase 8, the ratio of the amorphous phase composed of the metal element oxide that is easily deformed is relatively reduced in the grain boundary phase 8. Since the deformation of the field phase 8 can be suppressed, the rigidity of the molten metal end tab can be increased.

  Further, since the heat resistance is improved as compared with the case where the grain boundary phase 8 includes only an amorphous phase and an oxide, deformation at a high temperature can be suppressed.

  The form of magnesium aluminate and silicic acid nitride can be confirmed by measuring with an X-ray diffractometer (XRD) or an X-ray microanalyzer (EPMA).

  [Embodiment 5 of Ceramic Sintered Body] Further, it is preferable that the end tab 10 for welding has a boron nitride content of 3 mass% or more and 20 mass% or less. In the case where the above-described configuration is satisfied, the opposing surface can be a dense surface, and the high adhesion preventing action of boron nitride makes it difficult for the molten metal to adhere. 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.

  Since the crystal structure of boron nitride is rhombohedral, a part of the unit cell constituting the columnar crystal of silicon nitride penetrates into the unit cell of rhombohedral boron nitride at the time of sintering. It is considered that the bond strength is increased because the plane crystal boron nitride and silicon nitride are firmly bonded and the bonded crystal has a complicated shape.

  Here, the content of each component in the facing surface 10a is determined by identifying the components in the facing surface 10a using an X-ray diffractometer (XRD) and then using an 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 from the opposing surface 10a in the depth direction to a depth of about 30 μm to 50 μm was used as a sample, and the element content was determined using an ICP emission spectroscopic analyzer (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 facing surface 10a to a depth of about 30 μm to 50 μm is used as a sample, and a reit using XRD 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, a silicon powder (average particle size D ₅₀ = 0.5 to ₁₀₀ μm) and a silicon nitride powder (α conversion ratio of 50% or more, average particle size D) ₅₀ = 0.5-10 μm), and yttrium oxide powder (average particle diameter D ₅₀ = 0.5-10 μm) and aluminum oxide powder (average particle diameter D ₅₀ = 0.5-10 μm) as a sintering aid. ) And prepare. Then, the first starting material is obtained by mixing the silicon nitride powder and the sintering aid 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 yttrium oxide powder and 2 powders of aluminum oxide out of the total 100 mass% of the first starting material. Weigh so that it becomes 9 mass% or more and 7.3 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 first starting material. 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.

  In addition, in order to obtain a ceramic sintered body containing a second silicide which is a silicide of tungsten or molybdenum, powder of tungsten oxide or molybdenum oxide may be appropriately weighed and added to the first starting material. 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, the first starting material is mixed with various binders such as polyvinyl alcohol (PVA) and polyethylene glycol (PEG) together with, for example, a barrel mill, a rotating mill, a vibration mill, a bead mill, a sand mill or an agitator mill and mixed in a wet manner.・ Crush into slurry. Furthermore, you may add a thickening stabilizer, a dispersing agent, a pH adjuster, an antifoamer, etc.

  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 in which the opposing surface contains more silicide than at least one of chromium, manganese, iron and copper, the inside of chromium oxide, manganese oxide, ferric oxide and copper oxide can be obtained. A nitride using the first starting material to which any one kind of powder is added is placed in a closed firing container, and a degreased body made of metal silicon and silicon dioxide is also placed in the firing container. By doing so, the atmosphere may be controlled. In addition, the molar ratio of metal silicon to silicon dioxide in the degreased body is set to Si: SiO ₂ = 0.6 to 1.4: 1.

  Further, in order to obtain a welding end tab having a carbon content of 40 atomic% or more on the opposite surface, the nitride is placed in a closed firing container made of carbon and fired by the method described above. do it.

  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 an equivalent circle diameter of 1 μm or more and 5 μm or less on the facing surface is 2000 or less per 0.15 mm ² , The mass of the welding end tab may be 0.4 g / cm ³ or less.

[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. Note that the composition formula to obtain a _{Si 6-Z Al Z O Z} N 8-Z (z = 0.1~1) silicon nitride is a β- sialon represented by the solid solution amount z is 0.05 A silicon nitride powder of 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 second starting materials are mixed 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, etc. It can grind | pulverize to make a slurry and can manufacture through the process similar to the manufacturing method of 1st 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. First, a metal silicon powder and a silicon nitride powder having a β conversion ratio of 20% or less are prepared, and a mass ratio of (metal silicon powder) / (silicon nitride powder) is 1 or more and 10 or less. So as 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.

  Moreover, the 2nd powder which weighed the powder of magnesium aluminate and the powder of the 1st metal compound as a sintering auxiliary agent is obtained.

  Here, when the total of the first powder and the second powder is 100% by mass, the powder weighed so that the second powder is 10% by mass to 23% by mass is used as the third starting material. The first 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.

  [Method for Producing Ceramic Sintered Fourth Embodiment] To obtain the fourth embodiment of the ceramic sintered body, first, a third metal compound powder was weighed as a sintering aid. Obtain a powder. Here, when the sum total of the 3rd powder and the 1st powder used with the manufacturing method of a 3rd embodiment is 100 mass%, the 3rd powder will be 8.6 mass% or more and 18.6 mass% or less. Is used as the fourth starting material. The second metal compound is a rare earth oxide, a magnesium compound such as magnesium hydroxide, magnesium oxide or magnesium carbonate, aluminum oxide, or the like. More specifically, when the total of the first powder and the third powder is 100% by mass, the rare earth oxide powder is 7% by mass to 14% by mass, and the magnesium hydroxide, magnesium oxide or magnesium carbonate powder is 1 mass% or more and 4 mass% or less, and aluminum oxide powder may be 0.6 mass% or less (however, 0 mass% is not included).

  The fourth starting material is mixed and pulverized wet 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 manufactured through the same steps as the manufacturing method of the first embodiment.

  [Manufacturing Method of Ceramic Sintered Body in Fifth Embodiment] To obtain the ceramic sintered body in the fifth embodiment, the first starting material and the second material are formed on the surface of the molded body that becomes the opposing surface after firing. The paste obtained by adding the starting material, the third starting material or the fourth 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, for example, The step of drying at 60 ° C. or higher and 100 ° C. or lower may be performed. 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 as a nitrogen source gas
, NH ₃ , N ₂ H ₂ , NH ₄ Cl, NH ₄ Br, NH ₄ F, NH ₄ Hf ₂ and NH ₄ I, and Ar, He as a diluted carrier gas (carrier gas) Alternatively, at least one of H ₂ and H ₂ may be introduced into the reaction vessel, and gas phase synthesis may be performed at a temperature of 600 to 800 ° C. and 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.

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

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 4 whose thickness is 25 mm was welded to one main surface of the 3rd metal member 3 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 facing 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 is because the contact portion arranged at least facing the member to be welded is made of a ceramic sintered body containing silicon nitride as a main component, so that the wettability with respect to the molten metal is lower than that of Samples Nos. 2 and 3; Easy to remove. 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, for each sample, the components constituting the ceramic sintered body were identified by XRD, and the identified components were subjected to Rietveld analysis to determine the silicon nitride content. As a result, the silicon nitride content of each sample was 80% by mass or more, and silicon nitride and Y ₂ SiAlO ₅ 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 Y ₂ SiAlO ₅ N at 2θ = 32 to 33 ° and the peak intensity Y of silicon nitride at 2θ = 33.2 to 34.2 ° The ratio X / Y was calculated and the value is shown in Table 2.

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

Moreover, after grind | polishing the opposing surface of each sample and wash | cleaning the mirror surface obtained by grinding | polishing, it observed at 100 time magnification using an optical microscope, area was 0.15 mm < ² > (the length of a horizontal direction is 1000 micrometers, Obtained by particle analysis using image analysis software “A Image-kun” (registered trademark, manufactured by Asahi Kasei Engineering Corp.), taking a dark field image taken with a CCD camera over a range that is 150 μm in length. 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. 6 to 14 have a silicon nitride content of 80% by mass or more, Y ₂ SiAlO ₅ N is present in the grain boundary phase, and the ratio X / Y is 0.1 or more and 0.5 or less. There is no visible part. 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: First metal member 2: Second metal member 3: Third metal member 4: Fourth metal member 5: Wire for clamping 6: Back metal 7: Crystal of silicon nitride 8: Grain boundary phase 9: Open pores 10 : End tab for welding

Claims (12)

  A welding end tab, wherein at least a contact portion disposed to face a member to be welded is made of a ceramic sintered body containing silicon nitride as a main component. The facing surface of the contact portion has open pores,
2. The welding end tab according to claim 1, wherein a plurality of columnar crystals of silicon nitride are located inside the open pores so as to cross each other.   3. The welding tab according to claim 1, wherein the facing surface includes a larger amount of silicide including at least one of chromium, manganese, iron, and copper than the inside. 4.   The welding end tab according to any one of claims 1 to 3, wherein the facing surface has a carbon content of 40 atomic% or more. Wherein and the content of silicon nitride in the ceramic sintered body 80 mass% or more, there are _Y 2 SiAlO ₅ N in the grain boundary phase, wherein _Y 2 SiAlO ₅ N of 2 [Theta] = 32-33 ° in X-ray diffraction chart The ratio X / Y is 0.1 or more and 0.5 or less, where Y is the peak intensity of the silicon nitride having a peak intensity of X, 2θ = 33.2 to 34.2 °, and Y. The welding end tab according to any one of claims 1 to 4. 6. The white surface having an equivalent circle diameter of 1 μm or more and 5 μm or less exists on the facing surface, and the number of white spots is 2000 or less per 0.15 mm ² . End tab for welding as described in 1. The ceramic sintered body contains calcium, aluminum and rare earth element oxides, and the calcium content is 0.3% in terms of oxides out of a total of 100% by mass of calcium, aluminum and rare earth element oxides. Mass% or more and 1.5 mass% or less, the aluminum content is 14.2 mass% or more and 48.8 mass% or less in terms of oxide, and the balance is a rare earth element oxide,
Silicon nitride is β-sialon whose composition formula is represented by Si _6-Z Al _Z O _Z N _8-Z (z = 0.1-1), and the average crystal grain size is 20 μm or less (however, 0 μm The welding end tab according to any one of claims 1 to 6, wherein the end tab for welding is provided.   The ceramic sintered body contains gehlenite, and a half width of a peak intensity of gehlenite at 2θ = 31 ° to 32 ° in an X-ray diffraction chart is 0.5 ° or less. The welding end tab according to any one of 4.   The ceramic sintered body contains an oxide of rare earth elements, magnesium and aluminum, and the aluminum content is 0.6% by mass or less (excluding 0% by mass) in terms of oxide. The welding end tab according to any one of claims 1 to 4, wherein the welding end tab is provided. The grain boundary phase contains at least one of RESiO ₂ N, RE ₂ Si ₃ O ₃ N ₄ , RE ₄ Si ₂ O ₇ N ₂ and RE ₅ Si ₃ O ₁₂ N (RE: rare earth element). The welding end tab according to claim 9.   The welding end tab according to any one of claims 1 to 10, wherein the facing surface has a boron nitride content of 3 mass% or more and 20 mass% or less.   The end tab for welding according to claim 11, wherein the crystal structure of boron nitride is rhombohedral.