Method for producing joined ceramic-member object, joined ceramic-member object, and ceramic member

Abstract

Provided are: a method for producing a joined ceramic-member object, the method making it possible to efficiently produce a joined ceramic-member object which has high joint strength and is less apt to suffer joint separation at a joint interface; the joined ceramic-member object; and a ceramic member. The method for producing a joined ceramic-member object comprises: a planarization step in which surfaces to be bonded of two or more ceramic members are subjected to a planarization treatment; a stacking step in which the surfaces to be bonded of the two or more ceramic members are brought into contact with each other to form a ceramic-member stack; a roughening heat treatment condition determination step in which the ceramic members that have undergone the planarization step are separately subjected to heat treatments to determine roughening heat treatment conditions that make the surface to be bonded of each ceramic member, after the heat treatment, have a surface roughness Sa1 that is greater than the surface roughness Sa0 thereof before the heat treatment; and a joining step in which the ceramic-member stack is subjected to a heat treatment under the roughening heat treatment conditions, thereby forming the joined ceramic-member object.

Description

Method for manufacturing joined ceramic members, joined ceramic members, and ceramic members

[0001] The present invention relates to a method for manufacturing a joined ceramic member, a joined ceramic member, and a ceramic member.

[0002] Ceramics have properties such as high temperature resistance, high hardness, heat resistance, high chemical resistance, and a density lower than that of metals, and are used in a wide range of fields such as the electronics, automotive, space, medical, and chemical industries. In particular, when ceramics are translucent, they are used in optical applications such as solid-state laser media, X-ray scintillator materials, gamma-ray scintillator materials, magneto-optical device materials, light-emitting tubes, optical window materials, optical shutters, optical recording elements, and translucent bulletproof materials.

[0003] If the size and shape of ceramics could be adjusted to desired specifications, it would be possible to further enhance the functionality and expand the range of applications of ceramics. A technology for joining ceramic members to control such specifications has been proposed (Japanese Patent Laid-Open Publication No. 2003-48783).

[0004] Japanese Patent Application Laid-Open No. 2003-48783

[0005] However, the resulting bonded body may have insufficient bonding strength, and in some cases, separation may occur at the bonded interface due to insufficient bonding strength, making it impossible to achieve the desired function. Furthermore, bonding ceramics is generally not easy, and in order to find the optimal bonding conditions, it is necessary to repeatedly conduct trial and error, in which the bonded body is formed, the bonding strength is evaluated, and the results are then fed back to the setting of the bonding conditions. Therefore, a method for easily setting the bonding conditions is desired.

[0006] An object of the present invention is to provide a method for efficiently producing a joined ceramic member having high joining strength and being less susceptible to peeling at the joining interface, a joined ceramic member, and a ceramic member.

[0007] As a result of extensive research, the present inventors have found that the above-mentioned problems can be solved by the following configuration, and have thus completed the present invention.

[0008] In one embodiment, the present invention relates to a method for manufacturing a ceramic member joined body, the method including: a planarizing step of applying a planarizing treatment to respective surfaces to be joined of two or more ceramic members; a stacking step of bringing the two or more ceramic members into contact with each other at their surfaces to be joined to form a ceramic member laminate; a roughening heat treatment condition determination step, after the planarizing step, of heat treating the ceramic members individually to determine roughening heat treatment conditions such that the surface roughness Sa1 of the surfaces to be joined of the ceramic members after the planarizing treatment becomes larger than the surface roughness Sa0 of the surfaces before the heat treatment; and a joining step of heat treating the ceramic member laminate under the roughening heat treatment conditions to form a ceramic member joined body.

[0009] The inventors hypothesized that sufficient diffusion of the constituent elements of the ceramic members at the bonding interface would improve the bonding strength of a bonded ceramic member. However, precise measurement of temperature and concentration distributions near the bonding interface, which can affect the diffusion phenomenon, as well as direct observation of the diffusion phenomenon of the constituent elements at the bonding interface, are difficult. Therefore, as an alternative evaluation method, they focused on the change in surface roughness of the ceramic members before and after heat treatment before bonding. They hypothesized that if the surface roughness of the ceramic members increases upon heat treatment, the mobility of the constituent atoms on the surface will also increase, and as a result, the degree of diffusion of the constituent elements at the bonding interface will also increase. The inventors formed a bonded ceramic member using ceramic members whose surface roughness was confirmed to increase upon heat treatment, and found that the bonding strength was improved. The present invention is based on the novel finding that the change in surface roughness of the ceramic members during heat treatment correlates with the bonding strength.

[0010] In this method for manufacturing a joined ceramic member, roughening heat treatment conditions are determined in advance such that, when the ceramic members before joining are individually heat-treated, the surface roughness Sa1 of the to-be-joined surfaces after planarization treatment of the ceramic members becomes greater than the surface roughness Sa0 before heat treatment, and the ceramic members are joined based on these roughening heat treatment conditions, thereby making it possible to manufacture a joined ceramic member with high joining strength. Furthermore, without the need for trial and error, which involves evaluating the joining strength of the joined ceramic member and then resetting the joining conditions, the roughening heat treatment conditions determined in advance for the ceramic members before joining can be used as the joining conditions in the joining step, thereby further improving the yield from design to manufacturing of joined ceramic members regardless of the material or composition of the ceramic members.

[0011] In one embodiment, the planarization treatment is preferably a polishing treatment, which allows the surface roughness of the intended joining surfaces of the ceramic members to be efficiently adjusted to a desired range.

[0012] In one embodiment, the surface roughness Sa0 of the joining surfaces after the planarization treatment is preferably 0.6 nm or less, thereby increasing the adhesion (contact area) between the joining surfaces of the ceramic members and further improving the joining strength of the joined ceramic members.

[0013] In one embodiment, in the step of determining roughening heat treatment conditions, it is preferable to determine roughening heat treatment conditions such that the surface roughness Sa0 of the planarized bonding surfaces of the ceramic members before the heat treatment and the surface roughness Sa1 of the planarized bonding surfaces before the heat treatment satisfy the relationship Sa1 ≥ 2.0 × Sa0. By setting roughening heat treatment conditions that further roughen the bonding surfaces of the ceramic members, it is possible to promote diffusion of constituent elements at the bonding interface, thereby achieving further improvement in bonding strength.

[0014] In one embodiment, the roughening heat treatment conditions may be a heat treatment at a heat treatment temperature of 1100° C. or higher. According to the manufacturing method, appropriate roughening heat treatment conditions can be set depending on the material, composition, etc. of the ceramic member.

[0015] In one embodiment, the heat treatment in the bonding step is 1×10 －４ It is preferable to perform the bonding in a reduced pressure atmosphere of not more than Pa. This can eliminate the entrapment of air bubbles at the bonding interface of the ceramic members, thereby increasing the adhesion and further improving the bonding strength of the bonded ceramic members.

[0016] In one embodiment, after the heat treatment under the reduced pressure atmosphere, it is preferable to further perform a heat treatment under a pressurized atmosphere of 50 MPa or more, which can further promote the diffusion of the constituent elements at the bonding interface and can also remove pores (voids), thereby further improving the bonding strength.

[0017] In one embodiment, the ceramic member may be made of a translucent ceramic having a garnet-type crystal structure.

[0018] In one embodiment, the ceramic member may be rectangular parallelepiped, and the sum of its width, depth, and height may be 210 mm or more.

[0019] In one embodiment, the present invention relates to a joined ceramic member having a three-point bending strength of 340 MPa or more.

[0020] If the bonding strength of a ceramic member bonded body is low, the three-point bending strength will also be low. The ceramic member bonded body has a three-point bending strength of 340 MPa or more, which is comparable to the three-point bending strength of ceramic members that have not undergone a bonding process, and can exhibit excellent bonding strength. The three-point bending strength was measured according to the method described in the Examples.

[0021] In one embodiment, it is preferable that the transmitted wavefront distortion per inch in transmitted wavefront measurement at a wavelength of 633 nm is 63.3 nm or less. Also, in one embodiment, the optical loss coefficient determined by in-line transmittance measurement at a wavelength of 400 nm or more and 2000 nm or less is 0.002 cm －１ It is preferable that the following conditions are satisfied: In a joined ceramic member having one or both of these optical properties, the degree of diffusion of the constituent elements at the joining interface is high, and it can be said that the integration of the ceramic members has progressed to a high degree.

[0022] In one embodiment, the present invention relates to a ceramic member having a planarized surface, wherein, when heat treated at 1200°C or higher, the surface roughness Sa0 of the planarized surface before the heat treatment and the surface roughness Sa1 of the planarized surface after the heat treatment satisfy the relationship Sa1≧2.0×Sa0.

[0023] The ceramic members have surfaces that are roughened to a certain degree after heat treatment, and can therefore be suitably used to form a ceramic member bonded body.

[0024] A method for manufacturing a ceramic member bonded body, a ceramic member bonded body, and a ceramic member according to one embodiment of the present invention will be described below. The present invention is not limited to these embodiments. Combinations of preferred aspects are also preferred.

[0025] <Method for manufacturing joined ceramic members> The method for manufacturing joined ceramic members according to this embodiment (hereinafter also simply referred to as "manufacturing method") includes a planarizing step, a stacking step, a roughening heat treatment condition determining step, and a joining step. The manufacturing method may include other steps.

[0026] (Planarization Step) In the planarization step, the surfaces of two or more ceramic members to be joined are subjected to planarization treatment.

[0027] The material of the ceramic member is not particularly limited, and sintered bodies of various ceramic materials can be used. Examples of ceramic materials include YSZ (yttria stabilized zirconia), spinel (Al ２ O ３ -26 mass% MgO), PLZT (lead lanthanum zirconate titanate), Al ２ O ３ , ZrO ２ , YAG (Y ３ Al ５ O １２ ), LuAG (Lu ３ Al ５ O １２ ), TGG(Tb ３ Ga ５ O １２ ), TAG(Tb ３ Al ５ O １２), various sesquioxides, BGO (Bi ４ Ge ３ O １２ ), GAG (Gd ３ Al ５ O １２ ), Y ２ Zr ２ O ７ Translucent ceramics such as AlN, SiC, TiC / TiN (cermet), Si ３ N ４ , 2MgO.SiO ２ (Forsterite), MgO.SiO ２ (steatite), 2MgO.2Al ２ O ３ 5SiO ２ (Cordierite), Si ３ N ４ ・Al ２ O ３ (Sialon), BaTiO ３ , PZT (lead zirconate titanate), ferrite, 3Al ２ O ３ 2SiO ２ Among them, YAG (yttrium aluminum garnet) is a composite oxide of yttrium and aluminum (Y ３ Al ５ O １２ ) crystals with a garnet structure, which when doped with certain elements are suitable for use as phosphors and laser media, and even when undoped, are transparent in the visible light range and hard, making them suitable for use in windows that can be used in harsh environments (such as plasma), as well as optical materials such as mirrors and prisms.

[0028] The shape of the ceramic member is not particularly limited as long as it can form a joining surface, and any shape such as a rectangular parallelepiped, cube, prism, or cylinder can be used.

[0029] The size of the ceramic member can be appropriately set depending on the intended use, shape, size, etc. of the ceramic member bonded body. When the ceramic member is rectangular, the sum of the width, depth, and height may be 150 mm or more, 160 mm or more, 170 mm or more, 180 mm or more, 190 mm or more, 200 mm or more, 210 mm or more, 220 mm or more, 230 mm or more, 240 mm or more, or 250 mm or more. The sum of the width, depth, and height may be 2000 mm or less, 1500 mm or less, 1200 mm or less, or 1000 mm or less.

[0030] The number of ceramic members is not particularly limited as long as it is two or more, and may be three, four, five, six, seven, eight or more.

[0031] The two or more ceramic members may be the same or different in material, shape, size, etc. If the ceramic members have surfaces that are roughened by heat treatment, diffusion of constituent elements can occur at the joining interface, making it possible to join a variety of ceramic members.

[0032] Depending on the number of ceramic members (number of layers), the number of planned joining surfaces in one ceramic member may be 1, 2, or 3 or more. For example, when rectangular parallelepiped ceramic members are stacked in the height direction (thickness direction), the number of planned joining surfaces of the ceramic members located at the bottom and top is 1, and the number of planned joining surfaces of the ceramic members located in the middle is 2.

[0033] The planarization treatment for the intended joining surfaces of each ceramic member is not particularly limited as long as the desired surface roughness of the intended joining surfaces, adhesion and bonding strength between the ceramic members can be obtained. Specific examples of planarization treatment include polishing, grinding, cutting, etching, or a combination thereof. Among these, polishing, which can efficiently perform a high level of planarization, is preferred, and lapping, polishing (mirror polishing), or a combination thereof is more preferred. Polishing may be wet or dry, but wet is preferred. Known polishing methods can be used.

[0034] The surface roughness Sa0 of the intended joining surface after the planarization treatment is preferably 0.6 nm or less, more preferably 0.5 nm or less, and even more preferably 0.4 nm or less, taking into consideration the adhesion and bonding strength between the ceramic members. The lower limit of the surface roughness Sa0 is preferably as small as possible, but may be 0.1 nm. The method for measuring the surface roughness Sa is as described in the Examples.

[0035] After the planarization treatment, cleaning is preferably performed to remove abrasives, organic substances, inorganic substances, metal compounds, etc. adhering to the surface (surface to be joined) of the ceramic member. Examples of cleaning liquids include ultrapure water, basic cleaning liquids, acidic cleaning liquids, and combinations thereof. Sequential cleaning with multiple cleaning liquids may be performed. A basic cleaning liquid is a liquid in which a basic substance such as sodium hydroxide, sodium carbonate, or sodium phosphate is dissolved or dispersed in water. An acidic cleaning liquid is a liquid in which an acidic substance such as hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, citric acid, or acetic acid is dissolved or dispersed in water. Ultrasonic treatment or heating may be performed during cleaning.

[0036] Furthermore, heat treatment may be performed to remove moisture and hydroxyl groups present on the surfaces (surfaces to be joined) of the ceramic members. The heat treatment temperature is set within a range above the temperature at which moisture and hydroxyl groups are removed and below the temperature at which the surface roughness Sa0 of the surfaces to be joined of the ceramic members before the heat treatment is maintained even after the heat treatment. The heat treatment temperature is preferably 800°C or higher and 1000°C or lower. Thereafter, the ceramic members are cooled to a predetermined temperature and subjected to the next lamination process.

[0037] (Laminating Process) In the laminating process, the two or more ceramic members are brought into contact with each other at their intended joining surfaces to form a ceramic member laminate. Since the intended joining surfaces of the ceramic members have been subjected to a planarization treatment, the intended joining surfaces of the ceramic members can be adhered to each other by intermolecular forces. The required number of ceramic members are laminated to form a ceramic member laminate.

[0038] The fact that the ceramic members are in close contact can be confirmed by the fact that Newton's rings (interference fringes) that appear at the bonded interface immediately after lamination can no longer be visually observed.

[0039] (Roughening Heat Treatment Condition Determination Step) A roughening heat treatment condition determination step is performed at any stage after the planarization step and before the bonding step. In the roughening heat treatment condition determination step, the ceramic members are heat-treated individually, and roughening heat treatment conditions are determined such that the surface roughness Sa1 of the bonding surfaces of the ceramic members after the planarization treatment is greater than the surface roughness Sa0 before the heat treatment. By determining in advance, before the bonding step, roughening heat treatment conditions that provide a degree of change in the surface roughness of the bonding surfaces that is correlated with the bonding strength, the bonding strength of the ceramic member bonded body can be efficiently improved. Furthermore, since the bonding strength can be controlled simply by determining the degree of change in the surface roughness of the bonding surfaces due to the heat treatment of the ceramic members without actually bonding the ceramic members, the manufacturing efficiency of the ceramic member bonded body can be significantly improved.

[0040] Elements of the roughening heat treatment conditions include the heat treatment temperature, heat treatment time, heat treatment atmosphere, etc. These elements can be appropriately adjusted and set depending on the material, shape, size, etc. of the ceramic member so that the surface roughness Sa1 of the intended joining surface after the planarization treatment of the ceramic member is greater than the surface roughness Sa0 before the heat treatment. The higher the heat treatment temperature and the longer the heat treatment time, the more the roughening of the intended joining surface can be promoted. Among these, the heat treatment temperature is dominant in roughening the intended joining surface, so the roughening heat treatment conditions can be determined mainly from the perspective of the heat treatment temperature.

[0041] The roughening heat treatment conditions may be set depending on the properties of the ceramic member, etc. The heat treatment temperature is preferably 1100° C. or higher. The upper limit of the heat treatment temperature can be any temperature within the temperature range that does not exceed the melting point of the constituent material of the ceramic member.

[0042] The heat treatment time (the time for which the maximum temperature is maintained) is not particularly limited, and may be from 1 hour to 24 hours, or from 5 hours to 10 hours. The heat treatment atmosphere may be an air atmosphere or an inert gas atmosphere such as nitrogen gas or argon gas.

[0043] In this step, it is sufficient to determine the roughening heat treatment conditions such that the surface roughness Sa0 of the planarized joining surface of the ceramic member before heat treatment and the surface roughness Sa1 after heat treatment satisfy the relationship Sa1 > Sa0, but it is preferable to determine the roughening heat treatment conditions such that the relationship Sa1 ≥ 2.0 × Sa0 is satisfied. The rate of change in surface roughness Sa before and after heat treatment more preferably satisfies the relationship Sa1 ≥ 2.5 × Sa0, and even more preferably satisfies the relationship Sa1 ≥ 3.0 × Sa0. By increasing the rate of change in surface roughness Sa before and after heat treatment, the diffusion of constituent elements at the joining interface can be further promoted, and the joining strength can be further improved.

[0044] In the joining step, the ceramic member laminate is heat-treated under the roughening heat treatment conditions to form a ceramic member bonded body. By heat-treating the ceramic member laminate in accordance with the roughening heat treatment conditions (heat treatment temperature) determined in the roughening heat treatment condition determination step, a ceramic member bonded body with high bonding strength can be efficiently manufactured.

[0045] In this step, the heat treatment is preferably carried out under a reduced pressure atmosphere. －３ Pa or less is preferable, and 5 × 10 －４ Pa or less is more preferable, and 1×10 －４ It is more preferable that the bonding strength is not more than 100 Pa. This can eliminate the entrapment of air bubbles at the bonding interface of the ceramic members, thereby increasing the adhesion, and further improving the bonding strength of the bonded body of ceramic members.

[0046] The heat treatment time under reduced pressure (the time for which the maximum temperature is maintained) is preferably 1 hour or more and 24 hours or less, and more preferably 5 hours or more and 10 hours or less.

[0047] In this step, after the heat treatment under reduced pressure, it is preferable to further perform the heat treatment under a pressurized atmosphere of 50 MPa or more. The lower limit of the pressure during pressurization is more preferably 80 MPa, even more preferably 100 MPa, and particularly preferably 120 MPa. The upper limit of the pressure during pressurization is more preferably 200 MPa, even more preferably 180 MPa, and particularly preferably 160 MPa. This can further promote the diffusion of the constituent elements at the bonding interface and can remove pores (voids), thereby further improving the bonding strength.

[0048] The heat treatment time under a pressurized atmosphere (the time during which the maximum temperature is maintained) is preferably from 1 hour to 24 hours, more preferably from 5 hours to 10 hours.

[0049] The heat treatment under a pressurized atmosphere can be suitably carried out by hot isostatic pressing (HIP).

[0050] <Ceramic Member Bonded Body> The ceramic member bonded body according to this embodiment is a bonded body having a three-point bending strength of 340 MPa or more. The lower limit of the three-point bending strength is preferably 350 MPa, more preferably 360 MPa, even more preferably 370 MPa, and particularly preferably 380 MPa. The upper limit of the three-point bending strength is preferably as high as possible, but may be 500 MPa, 480 MPa, 460 MPa, or 450 MPa. The ceramic member bonded body has a three-point bending strength of 340 MPa or more and can exhibit excellent bonding strength.

[0051] In a transmitted wavefront measurement of a ceramic member bonded body at a wavelength of 633 nm, the transmitted wavefront distortion per inch is preferably 63.3 nm or less, more preferably 42.2 nm or less, and even more preferably 31.7 nm or less. In a ceramic member bonded body that satisfies these optical properties, the degree of diffusion of the constituent elements at the bonded interface is high, and it can be said that the integration of the ceramic members has progressed to a high degree.

[0052] The optical loss coefficient obtained by measuring the linear transmittance of the ceramic member bonded body at wavelengths of 400 nm to 2000 nm is 0.002 cm －１ Preferably, it is 0.0018 cm or less. －１ More preferably, it is 0.0016 cm or less. －１ It is even more preferable that the optical loss coefficient is less than 1 / 2. In a ceramic member bonded body having these optical properties, the degree of diffusion of the constituent elements at the bonded interface is high, and it can be said that the integration of the ceramic members is highly advanced. When YAG is used as a phosphor or laser medium, the Y element constituting YAG may be replaced by a rare earth element from Ce (atomic number 58) to Yb (atomic number 70) to form a solid solution, or the Al element constituting YAG may be replaced by a transition metal element from Ti (atomic number 22) to Ni (atomic number 28) to form a solid solution. The optical loss coefficient obtained by the in-line transmittance measurement is defined as a value at a wavelength excluding the specific absorption by the element doped into the ceramic member.

[0053] <Ceramic Member> The ceramic member according to this embodiment has a planarized surface, and when heat-treated at 1200° C. or higher, the surface roughness Sa0 of the planarized surface before heat treatment and the surface roughness Sa1 of the planarized surface after heat treatment satisfy the relationship Sa1 ≧ 2.0 × Sa0. The surface roughness Sa0 of the planarized surface before heat treatment and the surface roughness Sa1 of the planarized surface after heat treatment preferably satisfy the relationship Sa1 ≧ 2.5 × Sa0, and more preferably satisfy the relationship Sa1 ≧ 3.0 × Sa0.

[0054] The ceramic member can be suitably used for forming a ceramic member bonded body by being a ceramic member whose surface is roughened to a certain degree after heat treatment. As such a ceramic member, the ceramic member described in the manufacturing method of the ceramic member bonded body can be suitably used, except that when heat treated at 1200° C. or higher, the surface roughness Sa0 of the planarized surface before heat treatment and the surface roughness Sa1 after heat treatment satisfy the relationship Sa1≧2.0×Sa0.

[0055] The present invention will be described in detail below using examples, but the present invention is not limited to the following examples as long as it does not depart from the gist of the invention.

[0056] Example 1-1: Production of Ceramic Member (Synthesis of YAG Powder) An aqueous yttrium chloride solution and an aqueous aluminum chloride solution, each with a molar concentration of metal ions of 0.5 mol / L, were mixed at a volume ratio of 3:5. The mixed aqueous solution was added to ammonium bicarbonate (2 mol / L) adjusted to pH 8.2, and the mixture was stirred and cured at a liquid temperature of 30°C for 48 hours to precipitate a precipitate that would become a YAG precursor. The YAG precursor precipitate obtained after stirring and curing was washed with ultrapure water and the precipitate was filtered by suction filtration. This process was repeated six times. After six washings and filtrations, the YAG precursor precipitate was dried at 200°C to obtain a dry YAG precursor powder. The dry YAG precursor powder was heat-treated in air at 1200°C to obtain a YAG powder.

[0057] (Preparation of YAG Molded Body) YAG powder, alcohol, and a dispersant were placed in a nylon resin container, followed by addition of nylon balls for grinding. The YAG powder was then wet-milled using a ball mill to prepare a YAG slurry. The particle size of the YAG powder in the slurry was measured using a laser diffraction / scattering particle size distribution analyzer, and it was confirmed that the 50% particle size was less than 1 μm. The slurry was removed from the nylon resin container, and the air in the slurry was stirred and degassed at a gauge pressure of -90 kPa. The degassed slurry was poured into a plaster mold, and a rectangular YAG molded body was produced by slip casting under a pressure of approximately 0.5 MPa.

[0058] (Sintering of YAG molded body) The YAG molded body was dried at 30°C until there was no change in weight, and then degreasing treatment was carried out in air at 750°C. The degreasing YAG molded body was heat treated in air at 1000°C to obtain a calcined body. －５ The sintered body was sintered at 1600°C in a reduced pressure atmosphere of 100 MPa or less to obtain a sintered body with a relative density of 90% or more. The sintered body was then heat treated at 1700°C in a pressurized atmosphere of 100 MPa or more to obtain a rectangular parallelepiped ceramic member (width 105 mm, depth 105 mm, and height 10.5 mm) made of a YAG sintered body with a relative density of 100%.

[0059] <Measurement of Surface Roughness Sa of Ceramic Members Before and After Heat Treatment (Determination of Roughening Heat Treatment Conditions)> Ceramic members (Samples 1 to 3) having planarized surfaces (surfaces to be joined) as described below were prepared, and the surface roughness Sa0 of the surfaces before heat treatment was measured. Next, the heat treatment temperatures were set to 1000°C, 1200°C, and 1400°C, the heat treatment time was set to 10 hours, and the heat treatment atmosphere was set to air. The ceramic members were then heat-treated at each heat treatment temperature. Thereafter, the surface roughness Sa1 of the surfaces after heat treatment was measured. The surface roughness Sa was measured using a scanning probe microscope (Hitachi High-Tech Corporation, "AFM-5100N") using the DMF method over an area of ​​10 micrometers x 10 micrometers. In addition, the surface roughness ratio Sa1 / Sa0 was calculated from the surface roughness Sa0 of the surfaces before heat treatment and the surface roughness Sa1 of the surfaces after heat treatment. The results are shown in Table 1. From this result, it was found that the heat treatment temperature of 1200° C. or higher was preferable as the roughening heat treatment condition in this example.

[0060]

[0061] Examples 2-1 to 2-2 and Comparative Example 2-1: Production of Ceramic Member Joints (Polishing of YAG Sintered Body) Two sintered bodies measuring 30 mm in width, 105 mm in depth, and 10.5 mm in height were cut from a YAG sintered body serving as a ceramic member. The surface of each sintered body (the surface to be joined: a 105 mm x 10.5 mm surface perpendicular to the width direction) was polished with a slurry containing alumina fine particles as an abrasive to achieve a mirror-like finish with a surface roughness Sa of 0.5 nm or less. The polished ceramics were washed with ultrapure water, alkaline, and acid while irradiating them with ultrasound to remove abrasives, organic matter, and metal deposits from the surface. The washed YAG sintered body was heat-treated in air at 900°C to remove moisture and hydroxyl groups present on the surface. The washed and heat-treated sintered body was removed from the heat treatment furnace at a temperature of 100°C or higher. The removed sintered body was then moved to a temperature- and humidity-controlled room at 25°C or lower and a relative humidity of less than 30%.

[0062] (Determination of Roughening Heat Treatment Conditions) The YAG sintered body that had undergone the polishing treatment was used as a sample for measuring the surface roughness Sa.

[0063] (Lamination of YAG sintered bodies) The polished surfaces (surfaces to be joined: 105 mm × 10.5 mm) of the two YAG sintered bodies that had undergone the above steps were brought into contact with each other, and the polished surfaces were adhered to each other by intermolecular forces. Whether the polished surfaces were adhered to each other was judged visually by the disappearance of Newton's rings.

[0064] (Joining of YAG sintered bodies) The YAG sintered body laminate with the polished surfaces in close contact with each other was heat-treated for 10 hours at the heat treatment temperature of 1000°C, as well as at the heat treatment temperatures of 1200°C and 1400°C determined in the determination of the roughening heat treatment conditions. －４ The atmosphere was reduced to a pressure of 100 MPa or less. Further, while maintaining the heat treatment temperature, the YAG sintered body laminate after the heat treatment was heat treated in a pressurized atmosphere of 100 MPa or more for 10 hours, thereby obtaining a YAG sintered body bonded body (ceramic member bonded body; width 60 mm, depth 105 mm, and height 10.5 mm).

[0065] <Measurement of three-point bending strength of bonded ceramic members and evaluation of delamination> A bonded ceramic member was processed into a shape (length (L) 40 mm × width (W) 4 mm × thickness (T) 3 mm, with a bonded interface centered in the longitudinal direction so as to be perpendicular to the longitudinal direction) in accordance with JIS R 1601:2008 (external support distance 30±0.1 mm) to obtain a bonded sample. The three-point bending strength of the obtained bonded sample was measured in a configuration in which a load was applied from above to the bonded interface. In addition, if the bonded interface (flat surface) was exposed on the fracture surface in the three-point bending test, it was determined that delamination occurred at the interface, and if the bonded interface (flat surface) was not exposed, it was determined that no delamination occurred at the interface.

[0066] <Measurement of transmitted wavefront distortion of bonded ceramic members> Two opposing surfaces (two surfaces parallel to the bonded interface) of the bonded sample obtained by the three-point bending strength measurement procedure were mirror-polished to parallel surfaces (surface roughness Sa of 0.5 nm or less), and the transmitted wavefront distortion of the bonded ceramic members was measured using an interferometer (Zygo, Verifire) in a configuration in which light was transmitted perpendicular to the bonded interface. At this time, the light source wavelength was set to 633 nm, and the value of the transmitted wavefront distortion per inch of optical path length was evaluated.

[0067] <Measurement of optical loss coefficient of bonded ceramic members> The two opposing surfaces (two surfaces parallel to the bonded interface) of the bonded sample obtained by the three-point bending strength measurement procedure were mirror-polished (surface roughness Sa of 0.5 nm or less), and the transmittance of the bonded ceramic members in the wavelength range of 400 nm to 2000 nm was measured using a spectrophotometer (U-4100) in a configuration in which light was transmitted perpendicular to the bonded interface. The optical loss coefficient was calculated using the transmittance T of the bonded sample (optical path length L = 4.0 cm) and the transmittance T0 measured in the same wavelength range for a plate-like sample (optical path length L = 0.5 mm) obtained by mirror-polishing the two surfaces of the largest area of ​​a plate (length (L) 0.5 mm × width (W) 4 mm × thickness (T) 3 mm) made from the ceramic members prepared above. Light loss coefficient = ln(T0 [%] / T [%]) / L [cm] (*ln represents the natural logarithm.)

[0068]

[0069] As can be seen from the results in Table 2, the ceramic member bonded bodies obtained in the examples were superior to the ceramic member bonded bodies of the comparative examples in all of the three-point bending strength, the presence or absence of delamination, the transmitted wavefront distortion, and the optical loss coefficient.

Claims

1. A method for manufacturing a ceramic member joint, comprising: a planarizing step of applying planarization treatment to the respective surfaces to be joined of two or more ceramic members; a stacking step of contacting the two or more ceramic members at their surfaces to be joined to form a ceramic member laminate; a roughening heat treatment condition determination step, after the planarizing step, of heat treating the ceramic members individually and determining roughening heat treatment conditions such that the surface roughness Sa1 of the surfaces to be joined of the ceramic members after the planarizing treatment becomes greater than the surface roughness Sa0 of the surfaces before the heat treatment; and a joining step of heat treating the ceramic member laminate under the roughening heat treatment conditions to form a ceramic member joint.

2. The method for producing a ceramic member assembly according to claim 1, wherein the planarization treatment is a polishing treatment.

3. The method for producing a ceramic member joint according to claim 1, wherein the surface roughness Sa0 of the intended joining surfaces after the planarization treatment is 0.6 nm or less.

4. A method for manufacturing a ceramic member joint as described in claim 1, wherein in the roughening heat treatment condition determination process, roughening heat treatment conditions are determined such that the surface roughness Sa0 before heat treatment and the surface roughness Sa1 after heat treatment of the planarized joining surfaces of the ceramic members satisfy the relationship Sa1 ≧ 2.0 × Sa0.

5. A method for producing a ceramic member joint according to any one of claims 1 to 4, wherein the roughening heat treatment conditions are a heat treatment at a heat treatment temperature of 1100°C or higher.

6. The heat treatment in the joining process is 1×10 －４ The method for producing a ceramic member bonded body according to any one of claims 1 to 4, wherein the method is performed in a reduced pressure atmosphere of 0.1 Pa or less.

7. The method for producing a ceramic member joint according to claim 6, wherein after the heat treatment under the reduced pressure atmosphere, a further heat treatment is carried out under a pressurized atmosphere of 50 MPa or more.

8. A method for producing a ceramic member joint according to any one of claims 1 to 4, wherein the ceramic members are formed from a translucent ceramic having a garnet-type crystal structure.

9. A method for producing a ceramic member joint according to any one of claims 1 to 4, wherein the ceramic member is a rectangular parallelepiped having a total of width, depth and height of 210 mm or more.

10. A ceramic member joint having a three-point bending strength of 340 MPa or more.

11. A ceramic member bonded assembly according to claim 10, wherein the transmitted wavefront distortion per inch when measured at a wavelength of 633 nm is 63.3 nm or less.

12. The light loss coefficient obtained by measuring the linear transmittance at wavelengths of 400 nm to 2000 nm is 0.002 cm －１ The ceramic member joint according to claim 10, wherein:

13. A ceramic member having a planarized surface, wherein when heat treated at 1200°C or higher, the surface roughness Sa0 of the planarized surface before the heat treatment and the surface roughness Sa1 of the planarized surface after the heat treatment satisfy the relationship Sa1≧2.0×Sa0.

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