JPS6225737B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention uses novel alumina fiber as a reinforcing material,
This invention relates to a fiber-reinforced metal matrix composite material (hereinafter abbreviated as FRM) that uses an aluminum-based metal as a matrix. The aim is to provide a metallic material that is lightweight, has heat resistance, and has excellent mechanical and mechanical properties such as strength, elastic modulus, and fatigue strength in tension, bending, and compression. It is. In recent years, due to rapid technological developments in many industrial fields such as aerospace, nuclear power, and automobiles, materials have become lighter and have superior mechanical properties such as strength and elastic modulus compared to conventional materials, and can be used in high or low temperature ranges. There is a strong desire for materials that can last a long time. However, with existing techniques, it has been difficult to supply materials that fully satisfy all of these conditions. As one of the materials that can meet these demands,
Reinforcement material is inorganic fiber with relatively low specific gravity.
FRM is being actively researched. As inorganic fibers used for these reinforcing materials, boron fibers, carbon fibers, silicon carbide fibers, whiskers such as alumina, etc. have been used so far. Furthermore, the matrix metal differs depending on the use of FRM. For example, when weight reduction is particularly required, magnesium, aluminum, or an alloy thereof is mainly used, and when heat resistance is particularly required, copper, nickel, titanium, or an alloy thereof is mainly used. Among these, FRMs using aluminum or aluminum alloy as the matrix metal are the most studied and prototyped. However, FRM reinforced with this aluminum
The reality is that it still has many drawbacks and cannot be used as a highly reliable material. For example, boron fibers are known as high-strength fibers for reinforcing matrix metals. These fibers easily react with aluminum and easily generate boron compounds at the interface between the fibers and the matrix at relatively high temperatures, resulting in a decrease in the strength of the FRM. For this reason, the above reaction is usually controlled by coating the fiber surface with silicon carbide, but this is still insufficient. Furthermore, boron fibers or silicon carbide-coated boron fibers have a large fiber diameter of around 100 μm, and therefore have the disadvantage of poor flexibility and poor moldability. Next, carbon fibers are easily oxidized in the air, and due to a reaction at the interface with the matrix metal Al.
Produces a brittle layer of Al ₄ O ₃ and reduces the strength of the composite material. Furthermore, since carbon fibers have good electrical conductivity, an electrolytic corrosion reaction occurs at the interface between the fibers and the matrix metal, resulting in a decrease in fiber strength. For this reason, it has the disadvantage of being susceptible to corrosion, such as salt water resistance. By the way, wetting between carbon and liquid phase aluminum is poor. Therefore, it has been proposed to coat the fiber surface for the purpose of improving wetting and suppressing the reaction at the interface between the fiber and the matrix. However, carbon fibers generally have a thin fiber diameter of 10 μm or less, and it is difficult to coat the entire surface of the fiber reliably and evenly. Furthermore, it is known to coat the surface of carbon fiber with silicon or titanium carbide (Japanese Patent Laid-Open No. 52
-27826, 52-28433) have the disadvantage that the coating is made of ceramic and does not have good wettability with aluminum, which limits the manufacturing method. There is also a method (Japanese Patent Publication No. 37803/1983) in which the surface of carbon fiber is coated with an organometallic compound and then composited with aluminum. This method requires (1) time and expense because it is coated with an organometallic compound that is not easy to handle industrially, such as triethylaluminum, and (2) carbon dioxide is coated with triethylaluminum or diethylaluminum hydride. Even if the fibers are surface-treated and coated with aluminum, an oxide film is immediately formed on this surface, so when composited with aluminum, interfacial bonding occurs due to the oxide film that exists at the interface between the fibers and the matrix metal. The strength is too low to fully demonstrate the strength of the composite material,
It has drawbacks such as: Furthermore, a method of coating the surface of carbon fibers with silicon oxide and silicon carbide is also known (Japanese Patent Laid-Open No. 52-36502). This method also has the disadvantage that it is difficult to reliably and evenly coat the entire surface of a large number of carbon fibers, and when reinforcing aluminum, the coated silicon oxide and silicon carbide are heated to a relatively high temperature to This has the disadvantage of causing a decrease in the strength of the composite material because it reacts with the metal and forms a discontinuous brittle layer at the interface between the coated fiber and the matrix metal. Furthermore, whiskers such as alumina and silicon carbide have extremely high tensile strength and elastic modulus. However, it is difficult to mass-produce whiskers with uniform diameter and length, which is the main reason why whiskers are expensive. Furthermore, when alumina whiskers are composited with a metal, since this structure is α-Al ₂ O ₃ , there is no disadvantage of reaction with the matrix metal as described above, but on the contrary, there is no reaction between the alumina whisker and the aluminum matrix. It has the disadvantage that it has poor wettability and tends to form pores in the composite material, resulting in poor physical properties of the composite material. The inventors of the present invention have made intensive studies to solve the various drawbacks of the above-mentioned reinforcing fibers, and have found that a composite material in which aluminum or aluminum alloy is reinforced with alumina fibers coated with a metal or an intermetallic compound described below is It was discovered that it is lightweight, highly heat resistant, and has extremely excellent mechanical and mechanical properties. The alumina fibers used in the present invention are continuous fibers having an alumina (Al ₂ O ₃ ) content of 72% by weight or more and 100% by weight or less, preferably 75% by weight or more and 98% by weight or less, and According to the results of studies conducted by the inventors, it has extremely high tensile strength and elastic modulus. Alumina fibers are much more flexible than boron fibers, and have greater oxidation resistance even at high temperatures than boron fibers or carbon fibers, so they can be used to create metal composite materials. Not only does it offer the manufacturing advantage of being extremely easy to manufacture, but it also does not easily react with a wide variety of metals and has excellent mechanical properties, allowing it to withstand temperatures from room temperature to high temperatures. Composite materials that have high specific strength and specific modulus over a wide temperature range up to It has completely new features that cannot be expected from conventionally used reinforcing fibers. Furthermore, unlike conventionally used reinforcing fibers, the alumina fibers have a large surface area, and therefore various coatings can be efficiently applied to improve the interfacial bonding between the fibers and the matrix. It has advantages. In other words, regarding the above-mentioned properties of the alumina fiber, its strength and elastic modulus are
In μm, these values are 20t/cm ² and 2200t/cm ² or more, respectively, and these values are 1250°C in an oxidizing atmosphere.
It will not be lost even if it is kept in For example, a fiber with a diameter of 10μ consisting of a composition of 75% by weight of alumina and 25% by weight of silica exhibits a tensile strength of 29t/cm ² and a tensile modulus of 2400t/cm ² .
It still has a tensile strength of 20t/cm ² or more even after being held at ℃ for 1 hour. Furthermore, the surface area of the alumina fibers, as measured by the Bett method, is approximately 100 m ² /g to ^{600 m 2} /g in the above composition range. The present invention improves the wettability between the fibers and aluminum by coating the fibers with such a large surface area with a metal or metal compound that wets well with aluminum and is difficult to dissolve in the liquid phase of aluminum. The aim is to provide an FRM that suppresses the reaction at the interface between fibers and aluminum, and has unprecedented strength and elastic modulus at all temperatures up to just below the melting point of the matrix metal. By the way, the composite material of alumina fiber and metal having a melting point of 1700° C. or less used in the present invention is already known (Japanese Unexamined Patent Publication No. 109903/1982), and various FRMs can be obtained. However, when aluminum or aluminum alloy is used as the matrix metal, it is difficult for the alumina fibers and the matrix metal to get wet relatively easily unless the fibers are surface-treated. In this case, relatively high impregnation pressure is required. Furthermore, in order to eliminate this drawback in the manufacturing method, a method is known in which the surface of alumina fiber is coated with metal nickel and composited with a metal whose melting point is 1700°C or less (Japanese Patent Application Laid-Open No. 109904/1983). When aluminum or an aluminum alloy is used as the matrix metal, intermetallic compounds such as Al ₃ Ni are formed at the interface between aluminum and nickel, and since these intermetallic compounds are brittle, the resulting composite material Mechanical properties such as tensile strength remain at lower values than those according to the invention. In order to obtain good fibers for reinforcing the conventional aluminum or aluminum alloys described above, the present inventors have developed a new alumina fiber with a type of aluminum having a maximum dissolution amount of 1% by weight or less in the liquid phase on the surface of the new alumina fiber. If the above metals or intermetallic compounds of these two types are coated and this is composited with aluminum or an alloy containing aluminum, the FRM manufacturing method will be simplified because the fibers and matrix metal will have good wetting. It was discovered that the resulting composite material is lightweight, highly heat resistant, and has extremely excellent mechanical and mechanical properties, leading to the present invention. The present invention will be explained in more detail below. First, the alumina fiber used in the present invention has an alumina (Al ₂ O ₃ ) content of 72% by weight or more and 100% by weight.
The content of silica (SiO 2 ) is preferably 75% by weight or more and 98% by weight or less, and the silica (SiO ₂ ) content is preferably 0% by weight or more, 28% by weight or less.
Less than 2% by weight, preferably 2% by weight or more, 25% by weight
It has the following composition. In addition, in the silica content, lithium, beryllium, boron, sodium, magnesium, silicon, phosphorus, potassium, calcium, titanium, Chromium, manganese, yttrium, zirconium,
It may be replaced with one or more oxides of lanthanum, tungsten, and barium. In addition, in the X-ray structure of the alumina fiber, α
- It is desirable that the material exhibits substantially no alumina reflection. Generally, in inorganic fibers, crystal grains of the inorganic substance that form fibers grow within the fibers at high temperatures, and fiber strength is significantly reduced due to grain boundary destruction between these crystal grains. According to the results of studies conducted by the present inventors, this phenomenon is characterized by the appearance of reflection by α-alumina in the X-ray diffraction image of the alumina fiber. Therefore, the alumina fiber used in the present invention must be manufactured so that reflection of α-alumina does not appear in its X-ray diffraction image. According to the findings of the present inventors, such alumina fibers have excellent properties as composite reinforcing fibers, as described below. first
It has a high tensile strength of 10t/cm2 or ^more and a high tensile modulus of 1000t/cm2 ^or more. Also, since it is made of stable oxide, it will not deteriorate even if exposed to high temperatures of over 1000℃ in the air for a long time. Since the main component is alumina, it is stable and does not react easily even when it comes into contact with various molten metals. Furthermore, it has a density of 2.5 to 3.5 g/cm ³ and is light. These performances depend on the silica content in the fiber, but the inventors have found that when the silica content is 28% by weight or less, preferably 2% by weight or more, 25
The best performance is achieved when the amount is less than % by weight. The alumina fibers described above can be produced by various methods. For example, a precursor fiber is obtained by spinning a viscous solution containing an aluminum compound (alumina sol, aluminum salt, etc.), a silicon compound (silica gel, ethyl silicate, etc.), and an organic polymer (polyethylene oxide, polyvinyl alcohol, etc.). in air at a temperature below the temperature at which reflections of α-alumina are visible in the X-ray structure. Alternatively, it can be produced by immersing organic fibers in a solution containing an aluminum compound and a silicon compound and then firing them in air. The most preferable alumina fiber is
Manufactured by the method described in No. 13768. That is, this method involves spinning a solution containing polyaluminoxane and a silicon compound to obtain precursor fibers, which are then fired in air to produce alumina fibers. The polyaluminoxane used here has the general formula A polymer having a structural unit represented by, for example, Y consists of one or more of the following residues. In other words, alkyl groups such as methyl, ethyl, propyl, and butyl groups, alkoxy groups such as ethoxy, propoxy, and butoxy groups, carboxyl groups such as formyloxy and acetoxy groups, halogens such as fluorine and chlorine, and hydroxyl groups. , phenoxy group, etc. Particularly preferred are polyaluminoxanes that do not soften or melt at temperatures below 300° C. during the step of firing the alumina precursor fibers. Examples of such aluminoxane include polyisopropoxyaluminoxane, polyacetoxyaluminoxane, polybutoxyaluminoxane, and polypropionyloxyaluminoxane. These polyaluminoxanes are produced by partial hydrolysis of organoaluminum compounds such as triethylaluminum, triisopropylaluminum, tributylaluminum, aluminum triethoxide, and aluminum tributoxide, and by substituting the organic residues of the resulting polyaluminoxane with other suitable groups. obtained by doing. It is sufficient that the degree of polymerization of the polyaluminoxane used here is 2 or more, and there is no particular upper limit, but from the viewpoint of ease of polymerization reaction, polyaluminoxane having a degree of polymerization of 1000 or less is generally used. Polyaluminoxane is generally ethyl ether,
It is soluble in organic solvents such as tetrahydrofuran, benzene, and toluene, and at appropriate concentrations becomes a viscous liquid with excellent stringiness. The relationship between the concentration of polyaluminoxane and the stringiness of its solution varies depending on the type of polyaluminoxane used, its degree of polymerization, the solvent, and the type and amount of the silicon-containing compound mixed as described below. Although it cannot be stated, the viscosity at room temperature is generally 1 poise or more.
Solutions below 5000 poise are suitable for spinning. The spinning solution must therefore be adjusted to provide a viscosity within this range. Adding a small amount of organic polymers such as polyethylene glycol, polyvinyl formal, and polyvinyl acetate, aliphatic carboxylic acids such as stearic acid and palmitic acid, and other appropriate organic substances to the spinning solution can improve spinnability. desirable. On the other hand, as a compound containing silicon to be mixed with

Polyorganosine having the structural unit of [Formula] Roxane,

A polysilicate ester having the structural unit of [Formula] (R ₁ and R ₂ are organic atomic groups) is suitable, but an organosilane having the structure R _o SiX _4-o (X is OH, OR, etc.) is suitable. Yes, R
is an organic atomic group, n is an integer of 4 or less), a silicate ester having a structure of Si(OR) ₄ (R is an organic atomic group), and other silicon-containing compounds in general can be used. It is desirable that the silicon-containing compound to be mixed has a high silica content, but one with a low silica content may also be used. In particular, when producing alumina fibers with a low silica content, the silica content of the silicon-containing compound to be mixed may be small. Further, it is desirable that the silicon-containing compound to be mixed is uniformly dissolved and mixed in the polyaluminoxane solution, but it may be dispersed and mixed without being dissolved. In some cases, it may be effective to mix two or more silicon-containing compounds into the polyaluminoxane solution. Furthermore, a small amount of lithium, beryllium,
Adding one or more compounds containing boron, sodium, magnesium, phosphorus, potassium, calcium, titanium, chromium, manganese, yttrium, zirconium, lanthanum, tungsten, etc. will improve the quality of the alumina fibers obtained. This is desirable for improving physical properties. For spinning from a mixed solution of a compound containing polyaluminoxane and silicon, so-called dry spinning is convenient, but other suitable spinning methods such as centrifugal spinning and blow spinning may be used. Spinning is carried out at room temperature, but the spinning solution can be heated if necessary. It is also desirable to control the atmosphere surrounding the spun fibers to obtain good results. Dry removal of the solvent contained in the fibers is not particularly necessary when the fibers are thin, but
This can also be done during or after spinning. The precursor fibers produced here are usually 1 to 600μ
It has an average diameter of However, it is not limited to this range. The alumina fiber precursor obtained in this way is formed into a fiber with a high concentration of alumina formed and uniformly continuous, which is extremely convenient for improving the physical properties of the alumina fiber after firing. It is something. The alumina fiber precursor obtained in this way is infusible to heat, and if it is fired as it is in an atmosphere containing oxygen such as air, it can be easily converted into alumina fiber without changing the fiber shape. Can be done. That is, if the precursor fiber is fired in an oxygen-containing atmosphere, for example, air, it will substantially change to an alumina fiber at about 700°C, with an
A transparent and strong alumina fiber can be obtained at ℃. In order to obtain these various alumina fibers, the precursor fibers may be fired in an inert atmosphere such as nitrogen or in vacuum, and then exposed to an oxygen-containing atmosphere to remove organic or carbonaceous materials. . Further, it is desirable to further sinter the obtained alumina fiber in a reducing atmosphere such as hydrogen in order to improve various physical properties of the alumina fiber. It is also desirable to maintain tension on the precursor fibers or alumina fibers during these firing steps in order to produce strong alumina fibers. In either case, the maximum firing temperature is set so that no reflection of α-alumina is seen in X-rays. In this way, by the method described in Japanese Patent Publication No. 51-13768, the fiber diameter is from 0.6 to 400 μ and the tensile strength is from 10 to
30t/cm ² , elastic modulus 1000 to 3000t/cm ² , in air
Alumina fibers are produced that are stable for long periods of time at temperatures above 1000°C, and such fibers are most suitable for use in the present invention. Next, the material, form, and method for forming a metal or intermetallic compound coating on the surface of the alumina fiber will be described. First, the covering material is
The maximum amount dissolved in aluminum in liquid phase is 1
It must be less than or equal to % by weight of one or more metals or an intermetallic compound of these two. This is because the conditions for the covering material of the alumina fibers include (1) good wetting with the matrix metal (aluminum and aluminum alloy), and (2) low reactivity with the matrix metal. First, as an evaluation of condition (1), when looking at the contact angle with liquid phase aluminum for ceramics such as oxides, carbides, nitrogen compounds, and borides, it is found that unless the temperature is significantly higher than the melting point of aluminum or aluminum alloy, the contact angle with liquid phase aluminum is If the angle is 90° or more, wetting is poor. Therefore, it is preferable that the coating material be a metal or an intermetallic compound that has good wettability with liquid phase aluminum, since it can easily form a composite of FRM. Next, condition (2) is that the solubility of the coating metal or intermetallic compound in liquid phase aluminum is low. This solubility can be evaluated from the binary phase diagram with aluminum. For example, Ni with a maximum dissolution amount of 6.1% by weight in liquid phase Al
If 33.2% by weight of Cu is coated on alumina fibers and composited with aluminum, wetting of the fibers and matrix metal can certainly be improved, and the impregnation pressure can be significantly lowered using liquid metal impregnation methods. However, as mentioned above, the coating diffuses into the matrix, forming a brittle intermetallic compound layer of Al-Ni and Al-Cu at the interface between the fibers and the matrix metal, and the coating is also used to suppress the reaction with aluminum. The layer is removed from the fiber surface and a reaction between the fiber and the aluminum occurs, leading to a decrease in the strength of the fiber and the resulting brittle material. Therefore, as coating materials, B (0.022), Zr (0.11), and Ti with a maximum dissolution amount of 1% by weight or less in the liquid phase are recommended.
(0.15), V (0.25), Cr (0.41), Hf (0.49), Ru
(0.69), Be (0.87), Co (1.0) [The weight percentage in parentheses is the maximum dissolution], preferably 0.5% by weight of the above
The following metals, more preferably 0.15% by weight or less of one or more elemental metals, or the above-mentioned two types of intermetallic compounds such as Ti/B and Zr/B can be applied to the present invention. In addition, when it is particularly required to reduce the weight of the composite material, a metal coating having a density of 10 g/cm ² or less is preferable. More preferably, metals (Be, B, Ti, Zr, Co) or intermetallic compounds thereof having a density of 7 g/cm ² or less are suitable for the present invention. Next, regarding the coating form, as long as the coating layer can improve wetting with the matrix metal and suppress the reaction between the fibers and the matrix, it is desirable that the thickness of this layer be as thin as possible. This is because if the coating thickness increases relative to the fiber diameter, the fiber volume content of the composite material cannot be increased, and sometimes the specific gravity of the composite material increases. The order of this thickness varies depending on the diameter of the alumina fiber, but in the case of a fiber diameter of 15 μm, it is 0.01 to 5 μm.
μm, preferably 0.05 to 1 μm, more preferably
The present inventors have confirmed that when the thickness is in the range of 0.1 to 0.5 μm, wetting between the fibers and the matrix metal can be improved and reactions at these interfaces can be suppressed. Furthermore, regarding the coating method, in order to form a coating of one or more metals or an intermetallic compound of these two types in which the maximum amount of aluminum dissolved in the liquid phase is 1% by weight or less on the surface of the alumina fiber,
(1) Melt plating method, (2) Thermal spray method (flame spraying, plasma spray), (3) Evaporation method (vacuum deposition, chemical vapor deposition, sputtering, ion plating), (4) Electrodeposition method (chemical plating), etc. The following method can be used. Although the fibers may be in the form of continuous alumina fibers, the present invention can be applied to either long fibers or short fibers. However, when short fibers are used, the aspect ratio (ratio of fiber length to fiber diameter) must be 10 or more, preferably 50 or more, considering the composite theory. Furthermore, in order to obtain metal matrix composite materials that meet various purposes, alumina fibers can be used in combination with other inorganic or metal fibers such as boron fibers, graphite fibers, and whiskers, such as in woven fabrics. . On the other hand, in the present invention, aluminum or an aluminum alloy is used as the matrix. An aluminum alloy is an alloy containing 40% by weight or more of aluminum and 1 to 5 of the following elements. The additive elements include lithium,
Examples include silver, copper, silicon, zinc, gallium, germanium, magnesium, manganese, chromium, nickel, lead, and tin. In aluminum alloys, the content of aluminum in the alloy composition is 40
The reason why the alloy is made to be more than % by weight is as follows. It is desirable that the coating material be applied to the surface of the alumina fibers evenly and as thinly as possible. Therefore, it is desirable that the coating material has extremely low solubility in molten aluminum. The bonding force generated by the interfacial reaction between the coating material and aluminum creates a composite material with excellent mechanical properties. However, as the content ratio of aluminum in the aluminum alloy decreases, the bonding strength at the interface between the coating material and aluminum continuously decreases. This means that titanium coating (coating thickness 0.3μ
m) Zn made by changing the composition ratio of alumina fibers as appropriate
- Composite with Al-based binary alloy (fiber volume content 50
It was confirmed that the aluminum content ratio was 40% by weight or more, as determined from the tensile and bending strength of the composite material and the state of the interface between the fiber and matrix at the fracture surface. To manufacture the metal composite material of the present invention in which aluminum or aluminum alloy is reinforced with alumina fibers coated with a metal or an intermetallic compound, all known manufacturing methods that have been proposed so far for FRM materials are used. be able to. The main methods are (1) liquid phase methods such as liquid metal impregnation, (2) solid phase methods such as diffusion bonding, (3) powder metallurgy (sintering, welding), and (4) thermal spraying. , deposition methods such as electrodeposition and vapor deposition, and (5) plastic processing methods such as extrusion and rolling. As the fiber volume content of alumina fibers in the composite material used in the present invention increases, the strength and
The elastic modulus increases. However, the upper limit of this volume fraction was 68% for composites made of continuous fibers or long fibers arranged in one direction, and 45% for composites made of randomly arranged short fibers. This is because when the fiber content exceeds these values, the tensile strength and bending strength tend to decrease. The meaning of the present invention is that the surface of the alumina fiber is coated with one or more single metals, or an intermetallic compound of two of these metals, in which the maximum amount of aluminum dissolved in the liquid phase is 1% by weight or less. In particular, this is an advantage of the composite material manufacturing method in that the wetting of the alumina fibers with aluminum or aluminum alloy is improved, and the impregnation pressure can be significantly reduced in FRM production methods such as the liquid metal injection method. The first thing to mention is that there is. Next, although it is possible to obtain a good composite material without surface treatment of the fibers, when alumina fibers coated with a metal or an intermetallic compound are used as in the present invention, aluminum or an aluminum alloy as a matrix metal becomes a metal. In order to cause an appropriate amount of interfacial reaction, the interface between the fibers and the matrix in the composite material must have an appropriate bonding strength, neither too strong nor too weak, and as expected from the fracture mechanics theory of composite materials, This system has the advantage of being able to exhibit even better mechanical properties such as strength. The alumina fiber-reinforced aluminum or aluminum-based metal composite material thus obtained according to the present invention has a density of 2.9 g/cm ³ , which is approximately 1/3 that of steel, when the fiber volume content is 50%. It is a lightweight material. The tensile strength is 100Kg/ ^mm2 or more, which is higher than that of carbon steel.
The specific elastic modulus (Young's modulus/density) is approximately twice that of steel. Regarding fatigue strength,
10 The stress at the time of fatigue failure after ⁷ cycles is equal to the static tensile strength.
It exhibits an extremely high value of 69-73%, and is a material with features not found in other metal alloys. Furthermore, since alumina fibers are electrically insulating, the product will not deteriorate due to electrolytic corrosion at the interface between the fibers and the matrix, which occurs when aluminum or aluminum alloy is reinforced with carbon fibers or boron fibers. This is a major feature of metal materials reinforced with alumina fibers. Another advantage of the present invention is that it is possible to obtain a product that is superior in weather resistance and oil resistance compared to fiber-reinforced resins, and is also heat resistant at high or low temperatures. EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited thereto. Example 1 Continuous alumina fibers with an average fiber diameter of 15 μm, a density of 3.05 g/cm ³ with a number of filaments of 200 (Al ₂ O ₃ content 85% by weight, SiO ₂ content 15% by weight, tensile strength
26.3t/cm ² , tensile modulus 2350t/cm ² ) into a chemical vapor deposition furnace heated to 800°C (soaking length: 10cm in the temperature range of 800±7°C), and 1cm/cm away from the other side.
While winding the fiber at a speed of
A mixed gas was fed at a rate of 10 min, and the surface of the fiber was coated with metallic titanium by the reducing action of hydrogen at around 800°C. It was confirmed by observation using a scanning electron microscope that the coating thickness on the fibers was as thin as 0.3 μm on average, and that the coating was uniform and even over the entire surface of the fibers. Furthermore, the fact that the titanium is coated means that the
Confirmed using ESCA650B). This metal titanium coated continuous alumina fiber is 150
They were cut into lengths of mm, bundled, and drawn in parallel into a mold tube with an inner diameter of 8 mm. Next, molten aluminum (purity 99.9
%), and the other end was vacuum degassed to achieve infiltration of aluminum between the alumina fibers. The system was then cooled from one direction to solidify the aluminum, yielding a unidirectionally strengthened FRM. This method reduces the fiber volume content in composite materials.
Ten pieces each of 30, 40, 50, and 60% composite materials were made. The tensile strength, tensile modulus, flexural strength, and flexural rigidity of the aluminum material reinforced with titanium-coated alumina fibers obtained in this way increase linearly at room temperature when the fiber volume content reaches 60%. I understood. For example, fiber volume content 50
% composite material had an average tensile strength of 102 Kg/mm ² , a bending strength of 138 Kg/mm ² , a compressive strength of 230 Kg/mm ² and a tensile modulus of 1.4×10 ⁴ Kg/mm ² . Example 2 The surface of the alumina fiber described in Example 1 was coated with metallic titanium by sputtering. Titanium sputtering was performed using an IB-3 type Eiko ion coater manufactured by Eiko Engineering, under an argon gas atmosphere, at a sputtering speed of 20 Å/min, to a thickness of 0.5 μ.
The fiber surface was uniformly coated with titanium. This was confirmed using a scanning electron microscope and an X-ray photoelectron spectrometer. The titanium-coated alumina fiber thus produced was composited with aluminum (purity 99.9%) by the liquid metal impregnation method described in Example 1. As a result of measuring the tensile strength and tensile modulus of FRM with a fiber volume content of 50% in the range of -200℃ to 600℃, it was found that aluminum composites reinforced with titanium-coated alumina fibers showed high resistance from low temperatures to near the melting point of aluminum. It was found that the tensile strength and tensile modulus were hardly changed. For example, the tensile strength is −
103Kg/mm ² at 200℃, 110Kg/mm ² at 25℃, 630℃
101Kg/ ^mm2 , and tensile modulus even at 630℃
1.26×10 ⁴ Kg/mm ² and the value at 25℃ (1.40×10 ⁴ Kg/mm 2
mm ² ) was confirmed to be maintained at 90%. Example 3 The surface of the alumina fibers described in Example 1 was coated with a titanium-boron intermetallic compound, and an aluminum alloy [Al-12Si (Silumin composition)] was prepared by the liquid metal infiltration method described in Example 1. It became complex. In other words, alumina fibers are heated in a chemical vapor deposition furnace (900℃ constant temperature) in which a mixed reaction gas of titanium tetrachloride (20ml/min), boron tribromide (20ml/min), and hydrogen gas (60ml/min) is flowing. , Soaking length [900~
890℃] area is 12cm) and 0.5cm/
Wind the fiber at a speed of min and apply the average amount to the surface of the fiber.
A titanium-boron intermetallic coating was applied to a thickness of 0.6μ. The coating thickness and the presence of titanium-boron were confirmed using a scanning electron microscope and an X-ray photoelectron spectrometer, respectively. A composite material was obtained by applying the liquid metal impregnation method shown in Example 1 with molten silmin maintained at 620° C. between the coated alumina fiber bundles. When the resulting composite material was subjected to a tensile test, it was found that the tensile strength was 110 at a fiber volume content of 50%.
Kg/mm ² and tensile modulus of 1400t/cm ² . In addition, tensile fatigue test pieces were cut from the remaining samples to measure fatigue strength. The measuring device is a Shimadzu servo pulser EHF-E5 type, and the measurement conditions are 25℃,
The output waveform is a sine wave with a repetition frequency of 30Hz and load control. The amplitude of the repeated stress (S) was varied, the number of repetitions (N) until fatigue failure was measured, and an SN curve was obtained. The results revealed that the stress at the time of fatigue failure at N= ¹⁰⁷ cycles was 69 to 73% of the static tensile strength, which was a very high value. This led to the discovery of features not found in other metal alloys.

Claims (1)

[Claims] 1 On the surface of the alumina fiber, which has a component of 72% by weight or more of Al ₂ O 3 and 28% by weight or less of SiO ₂ , and does not substantially show α- _{Al 2 O 3} reflection in the X-ray structure,
The reinforcing material is fibers coated with one or more single metals or intermetallic compounds of two types that have a maximum dissolution amount of 1% by weight or less in aluminum in the liquid phase, and aluminum or aluminum components with 40%
An alumina fiber-reinforced aluminum-based metal matrix composite material whose matrix is an alloy containing more than % by weight.