JPS6221861B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a low thermal expansion composite material, and by combining a metal with a Li ₂ O-Al ₂ O ₃ -SiO ₂ mineral powder having a low coefficient of expansion, The present invention relates to a low thermal expansion composite material whose coefficient of thermal expansion is reduced. [Prior Art] Conventionally, low thermal expansion materials include amber alloys, which are used as materials for parts of various measuring instruments, bimetals, watches, and the like. However, this amber alloy has a high specific gravity of 8 to 8.5, is expensive, and has problems in workability. Aluminum titanate, Indialite, and Petalite are known as low thermal expansion materials for ceramics, but all of these have low mechanical strength and thermal history, making it difficult to use them as precision machine parts. be. By the way, it is generally said that in a composite made of two or more materials, the characteristics of the composite are determined in proportion to the volume fraction of the characteristics of the individual materials. This is the so-called composite rule. For example, the coefficient of thermal expansion α _c of a composite made of n materials is expressed as follows. α _c =K ₁ α ₁ V ₁ +K ₂ α ₂ V ₂ +……+K _o α _o V
_o /K ₁ V ₁ +K ₂ V ₂ +...+K _{o Vo} ...... (1) In formula (1), α is the coefficient of thermal expansion, V is the volume fraction,
K represents the bulk modulus, and subscripts 1 to n indicate that it relates to the 1st to nth materials. Therefore, mineral powders with low coefficients of thermal expansion, metals and/or
or its alloy, formula (1) can be used, and it is thought that a metallic composite material with low thermal expansion can be obtained. [Problems to be solved by the invention] However, the above compounding law assumes that there is no interaction between the constituent materials, and in actual composite materials, there are interfacial diffusion phases and residual stress phases that occur during the manufacturing process. In addition, factors such as thermal stress at the interface due to the difference in coefficient of thermal expansion and modulus of elasticity between the constituent materials of the composite material act, and it is not easy to obtain a composite material with targeted properties. For example, even if metal and low thermal expansion mineral powder are combined, it is difficult to obtain a low thermal expansion metal composite material with excellent workability and high strength.
There have been few attempts to produce a composite material that combines the characteristics of metal and mineral powder with low thermal expansion. [Means for solving the problems] The low thermal expansion composite material of the present invention contains Fe, Cu,
40-90% of one or more of the following metals: Ni, Co, Mo, Ti, Cr, Al, Mn, Si, Zn, Be and W;
A low thermal expansion composite material characterized by containing 10 to 60% of Li ₂ O-Al ₂ O ₃ -SiO ₂ mineral powder (However, one or more of the above metals may be Fe, Cu,
Excludes one or more of the following metals: Ni, Co, Mo, Ti, Cr, and Al. ). Hereinafter, % indicates weight %. Note that the applicant has already developed Fe, Cu, Ni,
One or more metals selected from the group consisting of Co, Mo, Ti, Cr, and Al, and Li ₂ O−Al ₂ O ₃ −SiO ₂
An application has been filed for a low thermal expansion composite material containing mineral powder (Japanese Patent Application No. 59-72110. Hereinafter referred to as the earlier application) The present invention was completed by further research based on the invention of the earlier application. It is. When manufacturing the low thermal expansion composite material of the present invention, powders of these metals and alloys are usually mixed with mineral powder, molded and sintered, as described below. In doing so,
The grain size of the metal or alloy used is preferably 50 μm or less, particularly preferably an average grain size of 20 μm or less. If metal or alloy powder containing a large amount of particles with a particle size of 50 μm or more is used, it is difficult to obtain a high-density composite material. Note that it is not preferable to contain too much metal or alloy powder with a particle size of 5 μm or less because the metal or alloy powder is likely to be oxidized. In addition, the Li ₂ O-Al ₂ O ₃ -SiO ₂ mineral powder that can be used in the present invention has a molar ratio of Li ₂ O: Al ₂ O ₃ : SiO ₂ =
1:1:2 to 10 can be used, specifically, for example, Li ₂ O−Al ₂ O ₃ −2SiO ₂ (β-eucryptite), Li ₂ O−Al ₂ O ₃ −4SiO ₂ (β -spodiemene), _{Li2O - Al2O3-8SiO2} ( _petalite ), and the like. Note that any type of Li ₂ O−Al ₂ O ₃ −SiO ₂ mineral powder can be selected depending on the target properties of the composite material. When producing a composite material, the mineral powder preferably has a particle size of 500 μm or less, particularly preferably an average particle size of 10 μm to 200 μm. If a large amount of particles with a particle size exceeding 500 μm is contained, the sinterability will be adversely affected. Also, if the average particle size is less than 10 μm, the average particle size of the metal is 5 μm.
This is not desirable. (This is because, as will be described later, when manufacturing the low thermal expansion composite material of the present invention, it is preferable that the particle size of the mineral powder is at least twice the particle size of the metal or alloy powder.) Generally, metals are used. Or, in a composite material consisting of an alloy and mineral powder, thermal stress at the interface, which is the product of the strain between mutual crystal grains due to the difference in thermal expansion between the metal or alloy and the mineral powder, and the elastic modulus of the metal or alloy; Due to causes such as residual stress generated during the manufacturing process,
The thermal expansion differences between the constituent materials are no longer constant. That is, Li ₂ O−Al ₂ O ₃ − for metals or alloys.
There is a tendency that the effect of reducing the thermal expansion coefficient of SiO ₂ -based mineral powder is difficult to appear. However, as a result of extensive research by the present inventors, we found that metals or alloys and Li ₂ O−
Controlling the particle size of Al ₂ O ₃ -SiO ₂ based mineral powder (specifically, the larger the particle size of mineral powder relative to the metal or alloy, the more the thermal expansion coefficient of the mineral powder on the metal or alloy is reduced. It has been found that the influence of thermal stress and residual stress on the thermal expansion effect can be overcome by increasing the grain size of the mineral powder (preferably at least twice the grain size of the metal or alloy). It is. In other words, the larger the particle size of the mineral powder is compared to the particle size of the metal or alloy powder, the greater the effect of the mineral powder on reducing the coefficient of thermal expansion of the metal or alloy. This becomes noticeable when the grain size of the alloy is preferably twice or more. (If the particle size is less than twice, the effect of reducing thermal expansion will be small due to the effects of thermal stress and residual stress at the interface of the metal composite material as described above.) In addition, the particle size of the mineral powder may be smaller than that of the metal or alloy powder. It has also been found that if the particle diameter exceeds 10 times, the particle size of the Li ₂ O−Al ₂ O ₃ −SiO ₂ mineral powder becomes excessively large, making it difficult to obtain a high-density metal composite material. For this reason, when manufacturing the low thermal expansion composite material of the present invention, when blending the metal and/or alloy with the Li ₂ O-Al ₂ O ₃ -SiO ₂ mineral powder, it is necessary to It is preferable that the average particle size of the mineral powder is at least twice the average particle size and at most 10 times the average particle size. The compounding ratio for manufacturing the metal composite material of the present invention is 40 _{to 90% by weight of metal and 10 to 60% by weight of Li2O-Al2O3-SiO2 mineral powder .} If the content of the metal and/or its alloy is less than 40%, or if the content of the Li ₂ O−Al ₂ O ₃ −SiO ₂ mineral powder exceeds 60%, there is a The amount of intervening metal or alloy is reduced, and the metallic properties of the composite material are extremely reduced, resulting in lower strength and poor workability. Furthermore, if the content of the metal and/or alloy exceeds 90%, or if the content of the mineral powder is less than 10%, the effect of reducing the coefficient of thermal expansion by combining the mineral powder will hardly appear. . In the low thermal expansion composite material of the present invention,
Although there is some diffusion reaction between Li ₂ O−Al ₂ O ₃ −SiO ₂ minerals and the above metals or alloys, the amount of reaction is small and the metal, alloy, or Li ₂ O−Al ₂ O ₃ −
It does not affect the properties of the SiO ₂ -based mineral powder, and in a broad sense, the physical bond between the crystals of the constituent materials is the main one, and the crystal phase is metal or alloy and Li ₂ O.
-Al ₂ O ₃ -SiO ₂ mineral powder only. Therefore,
There is no formation of interfacial diffusion phases that would cause a shift in the combined effect of thermal expansion coefficients. To produce the low thermal expansion composite material of the present invention,
In general, the composition is manufactured by forming a uniformly dispersed mixture in advance by a known method and heating the mixture at 600 to 1300°C in a vacuum or in a non-oxidizing atmosphere. Of course, a high-density, high-strength composite material can be easily obtained by other means such as well-known hot pressing, hot isostatic pressing, and the like. Alternatively, the mineral powder may be dispersed in the molten metal and then cooled and solidified. [Effect] Metals and/or their alloys have low expansion coefficients.
By combining _Li2O - _Al2O3 - _{SiO2 -} based mineral powder, it is possible to reduce the coefficient of thermal expansion of the metal. [Examples of the Invention] The present invention will be explained in more detail below using Examples, Reference Examples, and Comparative Examples, but the present invention is not limited to the following Examples unless the gist thereof is exceeded. Example 1 Metal or alloy shown in Table 1 (average particle size 5 μm)
and β-eucryptite (purity 99% or more, average particle size 15 μm) are mixed in the proportions shown in Table 1, and isopropyl alcohol is added as a solvent and sodium hexametaphosphate (addition amount 1% by weight) is added as a dispersant. The mixture was mixed in a ball mill (alumina pot and alumina ball) for 3 hours. The obtained mixed powders were individually molded at a molding pressure of 1500 kg/cm ² , and the molded bodies were placed in a hot isostatic press machine (hereinafter referred to as
(referred to as HIP apparatus) under the processing conditions shown in Table 1 (Nos. 1 to 10 and No. 31). Table 1 shows the characteristics of the obtained sample. Reference Example 1 The formulation shown in Table 2 was prepared in the same manner as in Example 1 except that Fe, Cu, Ti, Co, Ni, Cr or Al or Ti-Fe alloy or Mo-Fe alloy with a particle size of 5 μm was used. They were mixed and molded in the proportions, and the resulting molded bodies were subjected to HIP treatment under the conditions shown in Table 2 (Nos. 11 to 21). Note that this reference example 1 is related to the earlier application mentioned above. The properties of the obtained sample are shown in Table 2. Comparative Example 1 Mixing and molding were carried out in the same manner as in Example 1, except that Fe or Cu with a particle size of 5 μm was used at the proportions shown in Table 3, and the obtained molded product was molded under the conditions shown in Table 3. HIP treated (No. 22-27). The properties of the obtained sample are shown in Table 3. From Tables 1 to 3, it can be seen that the low thermal expansion composite material of the present invention is lightweight and has high strength, as well as the material according to Reference Example 1, and has low thermal expansion.

【table】

【table】

[Table] [Effects] As detailed above, according to the present invention, a composite material having an arbitrary coefficient of thermal expansion in the range from near the coefficient of thermal expansion of metals and their alloys to close to zero is provided. . This low thermal expansion composite material and materials containing it have lower thermal expansion and weight than invar alloys, and can be manufactured at lower cost. Furthermore, it has higher strength than aluminum titanate (approximately 10 kg/mm ² or more). Therefore, it is ideal for parts to be attached to various equipment, particularly measuring instruments and precision instruments, which require a certain level of strength, light weight, and low thermal expansion. Also, it can be tightened well with other metals. If this metal composite material has a complicated shape and requires dimensional accuracy, it may be applied after processing such as cutting. At that time, since the exposed surface is metal, a glossy surface can be obtained. It is also possible to apply plating or coating to the outer surface. As described above, the low thermal expansion composite material of the present invention is lightweight, inexpensive, has high strength, and has extremely good workability, so it is suitable for parts for measurement and precision instruments, and has great utility value.

Claims (1)

[Claims] 1 Fe, Cu, Ni, Co, Mo, Ti, Cr, Al, Mn,
40-90% of one or more of the metals Si, Zn, Be and W, Li ₂ O-Al ₂ O ₃ -SiO ₂ mineral powder 10-90%
A low thermal expansion composite material characterized by containing 60% (however, one or more of the above metals is Fe, Cu, Ni, Co, Mo, Ti, Cr, Al) (Excluding those that are one type or two or more types.)