JP2016078041A - Joining method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve joining quality of large sized silicon carbide ceramic.SOLUTION: In a method for irradiating a joining portion 210 of a plurality of substrates 110 with a laser 220 to join the substrates 110, at least one of the substrates 110 is a ceramic substrate containing silicon carbide, irradiation width of the laser 220 for irradiating the joining portion 210 is not more than 1 mm, and output of the laser 220 is 100 W/mm2 or more and less than 180 W/mm2.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a method for joining silicon carbide ceramic materials.

  Silicon carbide ceramics are excellent in heat resistance and corrosion resistance, and are applied to high-temperature structural members and wear-resistant members. Furthermore, in recent years, application to members such as semiconductors and nuclear power has been studied.

  Ceramic members such as silicon carbide are generally produced by a powder sintering method, and it is technically and costly difficult to produce large-sized members, long members, complicated shape members, etc. by a powder sintering method. Is expensive. For this reason, it has been studied to produce a simple-shaped product and to apply it to a large member, a long member, a complicated-shaped member, etc. by joining them.

  As a bonding method of the silicon carbide ceramic material, a solid phase bonding method using a hot press or a brazing bonding using an active metal such as copper or titanium as a brazing material has been reported.

  In the case of a solid phase bonding method using a hot press, bonding is performed while pressurizing at a high temperature, so that the shape and size of the ceramic material that can be bonded are limited. On the other hand, in the case of brazing joining using an active metal as a brazing material, it is possible to join at a relatively low temperature by using a brazing material having excellent wettability, and it is often used as a joining method for ceramic materials. Yes.

  By the way, when producing a large member or a long member by joining, since a member is put in a heating furnace and joining is performed, a large heating furnace is required. Further, when a brazing material is used, the heat resistance temperature of the bonding material depends on the heat resistance temperature of the brazing material.

  Therefore, when a large, long member intended for application at high temperature is produced by a joining method, a high melting point brazing material is applied, and a method of locally heating only the part to be joined is required. ing.

Japanese Patent Laid-Open No. 7-24177

Hisayoshi Okamura, Brazing ceramics and metal, welding technology, July 1992, 87

  The problem to be solved by the present invention is to improve the bonding quality of large silicon carbide ceramics.

  In order to solve the above problems, for example, the configuration described in the claims is adopted.

  According to the present invention, the bonding quality of large silicon carbide ceramics can be improved.

Schematic diagram of junction structure Schematic diagram of laser irradiation method Laser irradiation result Joining test results Schematic diagram of laser irradiation width Results of SEM-EDX analysis of joints

  Hereinafter, embodiments of the present invention will be described in more detail with reference to the drawings. In addition, this invention is not limited to embodiment taken up here, A combination and improvement are possible suitably in the range which does not change a summary.

  Examples of the ceramic substrate include ceramics mainly composed of silicon carbide, composite ceramics composed of a matrix phase mainly composed of silicon carbide, and composite ceramics composed of fibers composed mainly of silicon carbide. . Moreover, although a zirconium alloy and the composite material of a zirconium alloy and silicon carbide are mentioned, if it is a base material containing silicon carbide, it will not be limited to these. Further, at least one of the base materials to be joined may be a base material containing silicon carbide, and the other base material may be a metal base material.

  Ceramics containing silicon carbide as a main component are generally produced by a reaction sintering method, a normal pressure sintering method, a hot press method, or the like. Among these, the hot press method needs to be pressurized at the time of sintering, and is not suitable for producing a member having a complicated shape. In the case of the reactive sintering method, sintering can be performed at a relatively low temperature of about 1600 ° C., and the dimensional change during sintering can be suppressed. However, the sintered body contains free Si and pores. In comparison with the other two methods, the mechanical properties are inferior. In the case of a normal pressure sintered body, although depending on the type of sintering aid, the sintering temperature is as high as about 2000 ° C, and the dimensions change during sintering. Need to be considered. The method for producing ceramics mainly composed of silicon carbide and the sintering aid can be appropriately selected depending on the shape of the member to be applied and the environmental conditions to be applied.

  Fibers mainly composed of silicon carbide include fibers produced by depositing silicon carbide on a carbon core wire by chemical vapor deposition (CVD), and organic silicon polymers such as polycarbosilane as precursors. Fiber (Nicaron (registered trademark)) obtained by crystallization, spinning by adding titanium alkoxide or zirconium alkoxide to an organosilicon polymer such as polycarbosilane, fiber containing titanium or zirconium obtained by mineralization (tyranno fiber), Examples thereof include fibers (SA fibers) obtained by adding aluminum alkoxide to an organosilicon polymer such as polycarbosilane and spinning and mineralizing. Of these, the use limit temperature of Tyranno fiber containing titanium is 1300 ° C, and the use limit temperature of Tyranno fiber containing zirconium is 1500 ° C, indicating high heat resistance. Preferred for use in the present invention for application purposes. Nicalon has been reported to take up oxygen in the infusibilization stage during production and cause a decrease in strength at 1300 ° C. or higher. For this reason, silicon carbide fibers (Hinicalon (registered trademark)) in which infusibilization is performed by an electron beam irradiation method or the like and the heat resistance is improved by reducing the amount of oxygen are more preferable. In addition, comparing the room temperature strength after heat treatment in Ar gas, Nicalon, hynicalon, Tyranno fiber, etc. show a decrease in strength by heat treatment at 1000 ° C. or higher, but SA fiber has strength even at 2000 ° C. It is more preferable because it does not show a decrease.

  As a method for producing a silicon carbide composite material in which silicon carbide fibers are combined, a chemical vapor immersion method (CVI method) in which a CVD gas is allowed to flow in the voids of a silicon carbide fiber preform to deposit a silicon carbide matrix on the fiber surface, Polymer impregnation firing (PIP method) method in which silicon carbide fiber fabric is densified and fired repeatedly into a slurry in which organosilicon polymer and silicon carbide powder are mixed, and silicon carbide nanoparticles and organosilicon compounds are slurried as silicon carbide fibers A nano-infiltration transition eutectic phase process method (NITE method) in which coating and firing are performed has been reported. Among these, the CVI method, the NITE method, and the like are preferable because a circular tube shape, a rod-shaped large member, a long member, and the like can be manufactured.

  The bonding material is bonded with a brazing material interposed between the base materials. As the brazing material to be used, a brazing material that does not form a mechanically and thermally fragile reaction phase with silicon carbide such as silicon, a silicon alloy, or a silicon compound is preferable from the viewpoint of reactivity with silicon carbide. Moreover, when assuming use at a high temperature of 1000 ° C. or higher, the melting point of the brazing material is preferably 1200 ° C. or higher.

  Examples of the shape of the base material include, but are not limited to, a plate material, a square material, a disk, a cylindrical tube, and a round bar. In addition, examples of the joint structure include a lap joint, a butt joint, and a fillet joint, but are not limited thereto. The shape and joining structure of these base materials can be appropriately selected according to the application and shape of the member to be applied.

  Examples of lasers include CO2 laser, YAG laser, excimer laser, fiber laser, disk laser, semiconductor laser, picosecond laser, nanosecond laser, and femtosecond laser. A laser beam having a wavelength of can be used. These can be appropriately selected according to the material and shape of the member to be applied and the brazing material.

  As the beam shape of the laser beam, a circular beam, an elliptical beam, a linear beam, or the like can be used. As for the beam shape, an optimum shape can be selected according to the shape and size of the joint.

  Hereinafter, specific examples will be described.

  FIG. 1 shows a schematic diagram of a joining structure. A butt joint structure was studied as a joint structure. Cobalt SiC (model CERASIC-B) was used for the base material 110, and a silicon (Si) wafer made by Niraco (model 5000045, φ100 × 0.5 mm thickness) was used for the brazing material 120. The size of the SiC material used for joining is 15 mm × 15 mm × thickness 2 mm.

  The butt joint material shown in FIG. 1 was joined by laser. The laser oscillator used is a fiber laser oscillator (model YLR-2000, maximum output 2 kW, wavelength 1070 nm) manufactured by IPG Photonics. A sample was placed in a vacuum chamber, and after reducing the atmosphere to 10 Pa or less, laser irradiation was performed.

  FIG. 2 shows a schematic diagram of laser irradiation. The laser beam 220 was irradiated to the joint portion 210 of the butt joint material shown in FIG. The laser irradiation conditions are: laser output: 200 to 1200 W, laser irradiation time: 5 to 180 seconds, and the shape of the laser beam 210 is circular (φ0.5 mm to φ15 mm) or linear (13 mm × 0.2 mm). The moving speed is 0 to 20 mm / s.

  FIG. 3 shows an example of the result of laser bonding. Depending on the laser irradiation conditions, results such as (a) bonding, (b) cracking of the base material, and (c) disappearance of the brazing material were obtained.

  FIG. 4 shows the bonding results when the laser output and the irradiation width on the substrate are changed. In FIG. 4, the laser irradiation width is a length 520 from the bonding interface (butting portion of the base material) to a region 510 where the laser is irradiated on the base material, as shown in FIG. 5. A circle mark indicates a case where bonding is possible, a triangle mark indicates a case where the base material is cracked, a square mark indicates a case where the brazing material has not melted, and a cross mark indicates a case where the brazing material has disappeared.

  As shown in FIG. 4, as the laser irradiation width on the substrate increases, cracks occur in the substrate even under conditions where the laser output per unit area is small. This is probably because the larger the irradiation width, the greater the energy applied to the base material and the greater the non-uniformity of the thermal stress generated in the base material, leading to destruction. On the other hand, as the irradiation width becomes smaller, cracking of the base material is suppressed. This is considered to be because the nonuniformity of the thermal stress is reduced by reducing the irradiation to the base material. When the irradiation width was 1 mm or less, cracking of the substrate was avoided, but when the laser output was less than 100 W / mm2, the brazing material did not melt and was not joined. Further, at 180 W / mm 2, the brazing material disappeared, so that joining was not possible. For this reason, the laser output is preferably 100 W / mm 2 or more and less than 180 W / mm 2.

  FIG. 6 shows the SEM-EDX analysis result of the joined portion of the joined body produced by the butt joint material (800 W) produced by laser heating. As shown in the SEM image of (a), cracks and peeling are not seen at the bonding interface between the brazing material Si and the SiC material. Further, as shown in the distribution of Si in (b) and the distribution of C in (c), no interface phase other than Si and SiC was detected at the bonding interface.

110 Base material
120 Brazing material
210 joints
220 Laser beam
310 crack
510 Laser irradiation area
520 Laser irradiation width

Claims (3)

  In the method of joining a plurality of base materials by irradiating a laser, at least one of the plurality of base materials is a ceramic base material containing silicon carbide, and an irradiation width of the laser irradiating the joint portions is 1 mm. The joining method is characterized in that the laser output is 100 W / mm 2 or more and less than 180 W / mm 2.   The bonding method according to claim 1, wherein a bonding material is sandwiched between the plurality of base materials, and the laser is irradiated to the bonding portion including the bonding material.   The bonding method according to claim 1, wherein at least one of the plurality of base materials is a silicon carbide composite material including a fiber containing silicon carbide.