JPS6220143B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention provides a low-expansion powder composition for bonding, particularly between non-oxide parts (parts), especially between silicon nitride parts (parts), between silicon carbide parts (parts), or between silicon nitride parts (parts). The present invention relates to a low-expansion powder composition suitable for bonding silicon parts (parts). In recent years, engineering ceramics whose main composition is silicon nitride or silicon carbide are being researched and developed. However, since these engineering ceramics are used for, for example, rotors and stators of gas turbines, cylinders, pistons, and fuel injection valves of internal combustion engines and diesel engines, there are strict requirements regarding their shape, dimensions, precision, etc. It is often difficult to manufacture the shape. Therefore, it may be possible to create parts with simple shapes and then glue them together to create parts with complex shapes, and several specific methods have been proposed. For example, JP-A-47-
As described in Japanese Patent Publication No. 34410, powdered glass is sandwiched between silicon nitride members to be bonded and heated under pressure, and as described in Japanese Patent Application Laid-Open No. 1982-25008, crystal powder is bonded. Examples include those that apply pressure and heat by sandwiching a sandwich between members. In any case, in the known methods, it is necessary or desirable to heat-treat while applying pressure in order to increase the strength of the bonded portion. However, as mentioned above, parts used as engineering ceramics often have complex shapes, and it is not always possible to heat-treat them while applying uniform pressure to the bonding surface.
It is often desirable to perform heat treatment without applying pressure. Therefore, the present inventors conducted various studies in order to make it possible to bond with sufficient strength for handling and excellent thermal shock resistance without applying pressure during heat treatment. It has moderate reactivity with silicon ceramics and silicon carbide ceramics, and is highly reactive with silicon nitride,
Having discovered a new adhesive composition with excellent wettability with silicon carbide, we hereby propose it as the present invention, the gist of which is as follows: SiO ₂ 30 ~65% Al ₂ O ₃ 0.5 ~ 25 B ₂ O ₃ 0.1 ~ 25 PbO 0.5 ~ 45 CaO 0 ~ 20 TiO _{2 0} ~ 18 ZnO 0.1 ~ 30 MgO 0 ~ 10 BaO 0 ~ 10 SrO 0 ~ 10 Na ₂ O 0 10-55% by weight _{of a} glass powder having a composition _{of ~ 10 Li2O0-10K2O0-10Sb2O30-3As2O30-3SnO20-5F0-3 ;} Cordierite, β as a low expansion filler powder
- A low-expansion powder composition for bonding non-oxide ceramics comprising 45 to 90% by weight of at least one of spodumene, aluminum titanate, and zircon. The reason for limiting the composition of the low-expansion glass powder will be explained. SiO ₂ : If it is less than 30%, the softening temperature of the glass may become too low and the coefficient of thermal expansion may become too large. When it is more than 65%, the softening temperature of the glass becomes too high and the solubility becomes poor. Preferably it is in the range of 35 to 60%. Al ₂ O ₃ : If it is less than 0.5%, the glass will devitrify and its solubility will be poor. If it is more than 25%, the softening point of the glass becomes too high, which is not preferable in terms of solubility. Preferably it is in the range of 1 to 20%. B ₂ O ₃ ; This component is used as a fluxing agent. 0.1
If it is less than %, it will be difficult to vitrify, and even if vitrified, the softening point will be too high. On the other hand, if it exceeds 25%, the softening point becomes too low and the coefficient of thermal expansion increases, which is not preferable. The preferred range is 0.5 to 20%. PbO: Used as a flux agent in the same way as the above components. If it is less than 0.5%, vitrification is difficult. Moreover, if it exceeds 45%, the coefficient of thermal expansion increases and the contact reaction with non-oxide ceramics causes significant reduction, which may impair the original properties. Preferably it is in the range of 1 to 40%. ZnO: Used as a flux agent and also has the effect of regulating crystallization in part, and is an essential component. Furthermore, it is more effective than PbO in terms of contact reactions with non-oxide ceramics. If it is less than 0.1%, the solubility of the glass deteriorates, and crystallization types become difficult to crystallize, which is not preferable. If it exceeds 30%, devitrification occurs during glass melting, which is undesirable. A preferred range is 0.5-25%. CaO, TiO ₂ , BaO, SrO, MgO} Although not essential components, the solubility and viscosity properties of the glass as well as the coefficient of thermal expansion can be adjusted by introducing these components. CaO: If it exceeds 20%, devitrification may occur during glass melting. Preferably 0-18%
It is. TiO ₂ : If it exceeds 18%, devitrification may occur during glass melting. Preferably 0-15%
is within the range of MgO, BaO, SrO: All are used to improve glass meltability. However, both
If it exceeds 10%, the expansion coefficient becomes too large. Preferably it is in the range of 0 to 8%. Na ₂ O, Li ₂ O, K ₂ O} Although not essential components, they can be used as fluxing agents to improve the solubility of glass. However, if it exceeds 10%, the softening point becomes too low and the coefficient of thermal expansion becomes too large. Preferably it is 0 to 8%. Sb ₂ O ₃ , As ₂ O ₃ , F} It is also possible to introduce these components that have solubility and a clarifying effect during glass melting. However, there is no effect if it is introduced more than necessary, and the preferable range is 0 to 0.
It is 2%. SnO ₂ ; Although not an essential component, the introduction of this component improves water resistance among glass properties. Therefore, it is effective when the purpose is to improve water resistance. However, if it is introduced in an amount of 5% or more, devitrification occurs during glass melting, making it impossible to obtain a homogeneous glass. Preferably it is in the range of 0 to 4%. The low expansion glass powder having the above composition has a softening point of 500 to 900℃ and a thermal expansion coefficient of 30 to 60×10 ^-7 /
℃, and when brought into contact with silicon nitride ceramics or silicon carbide ceramics,
Because the reaction at the interface is relatively good, there is almost no foaming, and the adhesion is extremely good. However, most of the
The thermal expansion coefficient of the glass composition as it is is too large (in the case of silicon nitride ceramics, the thermal expansion coefficient is approx.
34×10 ^-7 /℃, and in the case of silicon carbide ceramics it is about 45×10 ^-7 /℃), so excessive thermal stress will occur on the bonding surface, making it impossible to obtain good bond strength. . In order to control the above-mentioned thermal expansion coefficient mismatch and fluidity upon heating, the present invention uses 45 to 90% of at least one of cordierite, β-spodium, titanium-brown aluminum, and zircon as a low-expansion filler powder. In addition, it constitutes a low expansion powder composition for adhesive use. As a filler powder, cordierite is excellent in terms of thermal expansion and heat resistance. Similarly, β-spodumene (Li ₂ O, Al ₂ O ₃ , 4SiO ₂ ) is produced by melting and vitrifying a stoichiometric raw material mixture at about 1500°C, cooling it, pulverizing it, and then reheating it at 900°C. Manufacture. Zircon (ZrO ₂ , SiO ₂ ) is usually a natural product, but it is also possible to use one synthesized by solid-phase reaction of ZrO ₂ powder and SiO ₂ powder. Aluminum titanate (Al ₂ O ₃ , TiO ₂ ) is
SiO ₂ in an equimolar mixture of Al ₂ O ₃ powder and TiO ₂ powder,
It is manufactured by adding a sintering aid such as Fe ₂ O ₃ and firing at a high temperature of 1400 to 1500°C, synthesizing it by an inherent reaction, and pulverizing the obtained sintered body. The coefficient of thermal expansion of these fillers is as follows. β-spodiumen 5～15×10 ^-7 ℃ ^-1 Zircon 40～48 〃 Aluminum titanate -10～15×10 ^-7 ℃ ^-1 Cordierite is pure
It is represented by the chemical formulas of 2MgO, 2Al ₂ O ₃ and 5SiO ₂ , and naturally occurring ones do not necessarily have stoichiometric MgO, Al ₂ O ₃ and SiO ₂ as shown in the above chemical formula. In addition, cordierite is heated to 1500℃
After melting, it becomes amorphous when rapidly cooled.
This amorphous cordierite has a large coefficient of thermal expansion. 1300~1400 of this amorphous cordierite
When heat treated at ℃, it becomes crystalline cordierite. Crystalline cordierite is famous for its low coefficient of thermal expansion, and its coefficient of thermal expansion depends on the above heat treatment conditions (heat treatment temperature, heating rate to the heat treatment temperature, holding time to the heat treatment temperature, atmosphere during heat treatment) etc.), but approximately 10~
Many of them fall within the range of 20×10 ^-7 /°C, and they can be used effectively as long as they fall within this range. The low-expansion filler used in the present invention has a thermal expansion coefficient of 10 to 20× synthesized by the above method.
Crystalline cordierite with a temperature of 10 ^-7 /°C is optimal, but natural crystalline cordierite can also be used. The crystalline cordierite used in the present invention does not necessarily have to be stoichiometric, but only needs to have a coefficient of thermal expansion within the range of 10 to 25 x 10 ^-7 /°C. In the present invention, as mentioned above, the above filler is
It is used 90% of the time. The type and amount of filler is determined depending on the thermal expansion coefficient of the adhered object and the operating temperature, but from the fluidity point of view, if the amount exceeds the upper limit, the fluidity during heating will decrease too much and it will not wet the adhered object. Adhesive force will be reduced. If the amount is less than the lower limit, the fluidity during heating will increase, the stability of the adhesive layer will decrease, and foaming will increase. More preferably it is 55-85%. If the low-expansion glass powder and low-expansion filler powder explained above are too fine,
When melted at high temperatures, it is difficult for the contained gas to escape, creating an adhesive force that envelops air bubbles, and shrinkage is large due to heating. The particle size of these particles is preferably 0.5 to 44μ, preferably 1 to 10μ. Next, the present invention will be explained in more detail with reference to Examples. Example (1) First step First, each raw material such as silica sand, aluminum hydroxide, boric anhydride, antimony oxide, arsenous acid, red lead, limestone, magnesium hydroxide, alkali metal carbonate, etc. is mixed according to the target composition. The mixture is mixed to prepare a batch, and the batch is placed in a platinum crucible and heated and melted at 1300 to 1500°C for 2 to 4 hours in an electric furnace. Then, this molten glass is pulverized or formed into a plate shape, and then ground in a ball mill to a particle size of about 1 to 10 μm. (2) Second step Next, magnesium hydroxide, alumina, and silica sand are blended to produce stoichiometric cordierite. After mixing, the mixture is placed in a platinum crucible and heated to 1500°C or higher in an electric furnace. Heat and melt at a temperature above. Then, amorphous cordierite of about 1 to 10 mm obtained by crushing this molten glass was heat-treated at about 1350° C. for 5 to 20 hours to obtain crystalline cordierite. Next, this crystalline cordierite was ground into fine particles of 10 to 70μ in size using a ball mill. (3) Third step The low expansion glass powder obtained in the first step and the low expansion filler powder obtained in the second step, or
A predetermined amount of natural cordierite pulverized to a particle size of 10 to 70 μm was blended, and the mixture was mixed and further finely pulverized in a pot to obtain a low-expansion powder composition for adhesive use. Table 1 shows the compositions of the low-expansion glass powder and low-expansion filler powder obtained in the first and second steps. Table 2 shows the results of adhesion tests using these powders. In addition, the average particle size of the low expansion powder composition for adhesive obtained in the third step was 1 to 10μ, and all
It was between 0.5 and 44μ.

【table】

【table】

【table】

[Table] The tests and evaluations in Table 2 were based on the following. (1) Flow button test 1.5g of the low expansion powder composition for adhesive obtained in the third step was press-molded at 20Kg/cm ² to 12.5mmφ x 5
I made a mm flow button. Next, this was placed on a silicon nitride fired body 1 or a silicon carbide fired body 2 whose surface had been polished to a smooth surface, and heat-treated at 1200° C. for 30 minutes in a nitrogen atmosphere or in air. 〓1 A mixture consisting of 5wt% _{Y 2} O ₃ , 5wt% Al ₂ O ₃ , and the rest silicon nitride powder was hot pressed at 1750°C for 5 hours in a nitrogen atmosphere, resulting in a 50mmφ x 10mm piece with a 99% density. body. _〓2B4 A mixture consisting of 0.5wt% C, 1wt% C, and the rest silicon carbide powder was heated to 2000% in an Ar atmosphere.
99 obtained by hot pressing for 1 hour at ℃
% density 50mmφ x 10mm fired body. (b) Fluidity evaluation: 〇…The corners of the flow button are rounded and there is considerable wetting against the adhered object. Δ...Intermediate between 〇 and × ×...The shape of the flow button melts and completely collapses, or does not change and no wetting is observed against the adhered object. (b) Evaluation of adhesion: 〇…Does not peel off easily. △...Although it is adhered for a while, it peels off when a wedge is driven into the adhesive interface. ×...Although it is glued for now, it can be removed by hand. (c) Foaming property 〇…Visible to the naked eye, almost no bubbles are observed. △: Some bubbles are observed by naked eye observation. ×...Many bubbles are observed by visual observation. (2) Coefficient of Thermal Expansion The low expansion powder composition for adhesive obtained in the third step was press-molded at 200 kg/cm ² , a 20 x 2.0 x 35 mm compact was placed in a platinum crucible, and the firing temperature was as shown in Table 2. As shown in the firing time column, a 5 mmφ x 20 mm cylinder was cut out from the glass obtained by firing under the firing conditions, and the average value was measured using a coefficient of thermal expansion measuring device in the range of room temperature to 1000°C. (3) Adhesive bending strength On the 6 mm x 6 mm surface of a 6 mm x 6 mm x 12.5 mm silicon nitride fired body and a silicon carbide fired body manufactured using the same process as that used in the flow button test,
A slurry made by adding a vehicle containing isoamyl acetate and nitrocellulose or water (all examples are water additions) to the low expansion powder composition for adhesive obtained in the third step is applied to a thickness of 0.1 mm or less. The silicon nitride fired bodies and the silicon carbide fired bodies were then bonded together and fired under the firing conditions shown in the firing temperature and firing time columns of Table 2. A load was applied to the central part (ie, the bonded part) of the 6 mm x 6 mm x 25 mm bonded body thus obtained at a crosshead speed of 0.5 mm/min, and a bending strength test was conducted over a 20 mm span. All samples exhibited peeling from the adhesive portion. The adhesive bending strength was calculated using the following formula. R=3Wl/2bd ² R: Adhesive bending strength (Kg/cm ² ) W: Load (Kg) l: 〃 Span (cm) b: Sample width (cm) d: 〃 Thickness (cm) What has been explained above As can be seen, the low expansion powder composition for adhesives of the present invention exhibits excellent performance.

Claims (1)

[Claims] 1 Essentially in weight%: SiO ₂ 30-65% Al ₂ O ₃ 0.5-25 B ₂ O ₃ 0.1-25 PbO 0.5-45 CaO 0-20 TiO ₂ 0-18 ZnO 0.1 〜30 MgO 0〜10 BaO 0〜10 SrO 0〜10 Na ₂ O 0〜10 Li ₂ O 0〜10 K ₂ O 0〜10 Sb ₂ O ₃ 0〜3 As ₂ O ₃ 0〜3 SnO ₂ 0〜 10-55% by weight of glass powder with a composition of 5 F 0-3 and cordierite, β as a low expansion filler powder.
- A low-expansion powder composition for bonding non-oxide ceramics, comprising 45 to 90% by weight of at least one of spodumene, aluminum titanate, and zircon. 2 Essentially in weight%: SiO ₂ 35-60% Al ₂ O ₃ 1-20 B ₂ O ₃ 0.5-20 PbO 1-40 CaO 0-18 TiO ₂ 1-15 ZnO 0.5-25 MgO 0-8 BaO 0-8 SrO 0-8 Na ₂ O 0-8 Li ₂ O 0-8 K ₂ O 0-8 Sb ₂ O ₃ 0-2 As ₂ O ₃ 0-2 SnO ₂ 0-4 F 0-2 A low-expansion powder composition for bonding non-oxide ceramics according to claim 1, having a glass powder composition having a weight of 15 to 50%.