JPH0382725A - Metal matrix composite for sliding - Google Patents

Abstract

PURPOSE:To easily offer the composite having excellent mechanical characteristics such as wear resistance, strength and dimensional stability at a low cost, in a potassium titanate fiber reinforced aluminum light alloy, by mixedly using titanium oxide. CONSTITUTION:The metal matrix composite for sliding can be obtd. by subjecting a mixture including an aluminum light alloy, titanium oxide and potassium titanate fibers to hot forming. As the titanium oxide, those of rutile- type, anatase-type or the lower ones obtd. by reducing the above such as Ti2O3 and TiO are available. As the titanium oxide, fibers or grains are used, and their shape and size are not particularly limited. At this time, the uniform mixing of potassium titanate fibers with titanium oxide is easily executed and they are not made ununiform in the stage of compounding, by which the objective composite can easily be obtd. at a low cost.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention relates to a metal matrix composite material, and more particularly to a metal matrix composite material using titanium oxide and potassium titanate fibers as reinforcing materials and an aluminum light alloy as a matrix metal. This invention relates to matrix composite materials.

[Prior Art] In recent years, the method of controlling the rotation speed of the compressor has become the mainstream method for controlling room temperature in near conditioners, but as the demand for higher speed rotary compressors increases, High-strength, lightweight materials are required for vane materials, which are the main sliding parts.

Under these circumstances, recently, aluminum light alloy reinforced with silicon carbide whiskers, which has excellent mechanical properties such as abrasion resistance, strength, and dimensional stability, which are necessary for the sliding members of rotary compressors, has been developed for large-scale rotary compression. There are reports of its use in aircraft vanes.

However, since silicon carbide whiskers are expensive, the price of aluminum light alloy reinforced with silicon carbide whiskers will also inevitably be high, and it is said that reducing the price of the material will be an issue in order to increase the number of models that will be used in the future. ing.

Potassium titanate fiber-reinforced aluminum light alloy is known as a fiber-reinforced aluminum light alloy that is inexpensive and has excellent mechanical properties such as strength and dimensional stability. However, this light alloy does not have good wear resistance, which is one of the mechanical properties necessary for a sliding member of a rotary compressor.

One way to improve the wear resistance of the matrix using potassium titanate fibers as a reinforcing material is to mix fibers or particles with high Mohs hardness such as silicon carbide, silicon nitride, or alumina with potassium titanate fibers. JP-A-63-190127 and JP-A-83-190
No. 128. However, the above method has the drawback that it is difficult to uniformly mix the potassium titanate fibers and the above fibers or particles. As a result, when a light alloy and an inorganic material are composited, non-uniformity in the mixing ratio of fibers or fibers and particles of different sizes and shapes is promoted, making it difficult to reproducibly produce composite materials with constant physical properties. It was difficult.

[Problems to be Solved by the Invention] As described above, conventional metal matrix composites have excellent mechanical properties such as wear resistance, strength, and dimensional stability necessary for use as sliding members of rotary compressors, for example. The material is expensive or has problems with manufacturing technology, so it is not desirable as an industrial material, and there has been a desire to develop a new composite material.

An object of the present invention is to provide a metal matrix composite material that does not have the drawbacks of conventional composite materials, is inexpensive and easy to manufacture, and has excellent mechanical properties such as wear resistance, strength, and dimensional stability. .

[Means for Solving the Problems] The present inventors have conducted intensive research to solve the above problems, and as a result, have found that it is effective to use titanium oxide and potassium titanate fibers as reinforcing materials. , completed the present invention.

That is, the present invention provides a metal matrix composite material containing titanium oxide, potassium titanate fiber, and aluminum light alloy and having excellent mechanical properties such as wear resistance, strength, and dimensional stability.

The present invention will be explained in detail below. Potassium titanate fibers that can be used in the present invention include conventional potassium titanate fibers and potassium hexatitanate fibers (K2T) in which the amount of free potassium that can be eluted from the crystal structure is 15 ppm or less.
i60 engineering. ), and preferably potassium hexatitanate whiskers in which the amount of free potassium that can be eluted from the crystal structure is 15 ppm or less, particularly preferably 5 ppm or less, are effectively used. Potassium hexatitanate whiskers in which the amount of free potassium that can be eluted from the crystal structure is 15 ppm or less, preferably 5 ppm or less, are those that extremely reduce the amount of layered potassium titanate present inside the potassium hexatitanate crystal. It is a potassium titanate fiber made of aluminum, so it has low reactivity when composited with light alloys and has a good reinforcing effect. Such potassium titanate fibers are typically produced by the following method.

That is, a mixture of a titanium raw material compound and a potassium raw material compound blended in a ratio represented by the general formula K0-nTi02 (where n = 2 to 4) is fired at 900 to 1200°C to obtain bulk potassium titanate fibers. After the bulk product is soaked in water or hot water to separate the potassium titanate fibers into single fibers, acid is added to the slurry to adjust the pH to 9.3-9.7. By this, the composition of potassium titanate fiber is 20 (molar ratio) to TiO27 and 5
．． 95-6. The composition is converted to the composition of OO,
After further heating at 900 to 1150° C. for 1 hour or more, acid washing may be performed.

In the production of potassium titanate fibers, examples of titanium raw compounds include hydrous titanium oxide, titanium dioxide, and rutile ore, and examples of potassium raw compounds include compounds that yield 20 during firing, such as K O, K
Examples of OH include 2Co3 and KNO3.

Incidentally, the amount of free potassium in potassium titanate fibers can be measured by the following method.

That is, after dispersing a predetermined amount of potassium titanate fibers in water, the potassium eluted by boiling may be measured by high frequency inductively coupled plasma emission spectrometry, tip spectroscopy, atomic absorption spectroscopy, etc. . Further, since potassium liberated from the crystal structure of potassium titanate exists as potassium hydroxide in the aqueous solution after boiling, it is also possible to measure and calculate 9H of the solution.

In addition, the shape of the potassium titanate fiber has an average fiber length of 5
um or more, and the average aspect ratio (average fiber length/average fiber diameter) is preferably 10 or more.

The titanium oxide used in the present invention includes rutile titanium oxide, anatase titanium oxide, and lower titanium oxides obtained by reducing these, such as Ti2O3 and TiO.

The shape and size of titanium oxide are not particularly limited, but when performing composite formation using the molten metal casting method, it is better to use fibrous titanium oxide because it produces a preformed body in which potassium titanate fibers and titanium oxide are uniformly mixed. (preform) is easy to produce and practical.

Fibrous titanium oxide includes anatase-type titanium oxide fibers and rutile-type titanium oxide fibers, which are manufactured by extracting alkali ions in the crystal structure of layered alkali titanate fibers through an ion exchange reaction and then heating the fibers to 400°C or higher. Fibers and mixed phase fibers thereof are particularly advantageously used.

That is, since the titanium oxide fibers produced by the above method have almost the same shape and size as the potassium titanate fibers, it is easy to produce a uniform mixture with the potassium titanate fibers. Also, there is no possibility of non-uniformity when compounding.

Furthermore, even when titanium oxide particles are used, their surface properties are relatively similar to those of potassium titanate fibers, so when using reinforcing materials with completely different surface properties such as silicon carbide or alumina, It has the advantage that uniform mixing can be achieved much more easily than with other methods.

Furthermore, it was surprisingly found that titanium oxide reacts with aluminum light alloys during the forming process to form new compounds. Titanium oxide remains in the composite material as it is, and does not contribute to improving wear resistance with its original hardness, but forms a new substance with high hardness with the light aluminum alloy, which improves wear resistance. This contributed to improving wear resistance.

That is, in the composite material according to the present invention, the potassium titanate fiber acts as a fiber-shaped reinforcing material to improve the strength and dimensional stability of the aluminum light alloy, and the titanium oxide acts as a reinforcing material in the aluminum light alloy when combined with the aluminum light alloy. By reacting to form a highly hard substance, it functions to impart wear resistance to aluminum light alloys.

Note that the aluminum light alloy used in the present invention includes, for example, Al-Mg series, A(1-Mn series, 1-81 series,
AN -Mg-81 series, Al2-Cu series, Al1-Cu
-81 series, or AfI-Cu-Mg-Ni series, etc.
In the present invention, commonly used aluminum light alloys are
It can be used without any problems.

Further, the composite material according to the present invention can be obtained by molding the above-mentioned reinforcing material and an aluminum light alloy under heating.

Regarding the composition of the composite material of the present invention, the volume fraction of the matrix light alloy is preferably 94 to 50 Vo 1%, more preferably 88 to 60 Vo 1%, and the volume fraction of titanium oxide is preferably 1 to 15 Vo 1%, more preferably is 2~
10Vo1%, and the volume fraction of the potassium titanate fiber is preferably 5 to 35Vo1%, more preferably 10 to 3Vo1%.
The range is 0Vo1%. The volume fraction of the titanium oxide is IV
If o is less than 1%, the effect of improving wear resistance is insufficient;
If it exceeds 5Vo1%, the composite material becomes too hard,
This is not preferable because the processability, which is a characteristic of potassium titanate fiber-reinforced light alloys, is impaired. Furthermore, if the volume fraction of the potassium titanate fibers is less than 5Vo1%, the improvement effect on strength and dimensional stability is poor, and if it exceeds 35Vo1%, the degree of strength improvement of the composite material due to the increase in the volume fraction of the potassium titanate fibers will be reduced. It is small and undesirable from the cost standpoint.

The metal matrix composite material according to the present invention obtained as described above has excellent strength and wear resistance, and is used not only for vane materials of rotary compressors but also for sliding parts such as piston wear-resistant rings, piston rings, bearings, etc. Suitable for manufacturing moving parts.

The present invention will be explained in more detail with reference to Examples below. The following examples are given for illustrative purposes only and are not intended to limit the scope of the invention.

[Example] Example 1 1400 g of anatase-type titanium oxide and 8 g of potassium carbonate
After dry mixing with 00g, put it in an alumina crucible,
Temperature increase rate 250°C/hour in electric furnace, holding temperature 950°C,
After firing under conditions of a holding time of 2 hours, the temperature was lowered at a rate of 150° C./hour. The product is referred to as baked product I.

10. Place the baked product I in a stainless steel container. After putting it in warm water of Q and immersing it for 5 hours, stirring was started at 800 rpm and the water temperature was adjusted to 60°C. The pH was adjusted to O by dropping 5N sulfuric acid. After filtration, it was calcined at 500°C for 1 hour.

This fiber was identified by X-ray diffraction and was found to be a single phase of anatase titanium oxide. Furthermore, when the fibers were observed using a scanning electron microscope, the average fiber length was 40 parts.
The average fiber diameter was 0.6 part.

After putting the baked product I into 1ON hot water in a stainless steel container and soaking it for 5 hours, stirring was started at 800 rpm,
The water temperature was adjusted to 60°C. The pH was adjusted to 9.5 by dropwise addition of 5N hydrochloric acid. After this, if stirring is continued further, potassium ions will be eluted from between the layers of potassium tetratitanate, so p
Although H increased, hydrochloric acid was added dropwise at 30 minute intervals to adjust the pH to 9.5 until the pH increase was 0.1 or less when stirring was continued for 30 minutes after the addition of hydrochloric acid.

After filtration, it was calcined at 1000°C for 2 hours. 10 pieces of the fired product
After dispersing in hot water of fI, 1-N hydrochloric acid was added dropwise to
H was adjusted to 4. It was filtered and dried to obtain potassium titanate fibers.

This fiber was identified by X-ray diffraction and was found to have a tunnel structure and a single phase of potassium hexatitanate. Further, when the fibers were observed using a scanning electron microscope, the average fiber length was 40- and the average fiber diameter was 0.6-. Next, the potassium titanate fibers were pulverized using an Ishikawa-type milling machine, a predetermined amount was collected, dispersed in water, and boiled for 10 minutes, and the amount of potassium titanate in the aqueous solution was determined using I
The analysis was performed using a CAP-505 model high frequency inductively coupled plasma emission spectrometer, and the amount of chlorine ions in the aqueous solution was analyzed using a spectrophotometer 100-0101 manufactured by Hitachi, Ltd.

As a result, the potassium content contained as potassium chloride was removed and the free potassium eluted from the crystal structure of potassium titanate was calculated, and 3. It was ippm.

After dispersing the mixture consisting of 20Vo1% anatase type titanium oxide fiber and 80Vo1% potassium titanate fiber obtained as above in water, 5% by weight of colloidal silica based on the fiber weight was added and mixed, followed by filtration and processing. After pressure,
It was dried at 80° C. to produce a preform with a fiber content of 30 VOI%.

Next, the preform was preheated to about 600°C, then heated to 250°C, placed in a mold, and then heated to about 740°C.
Pour the molten metal of JIS standard AC8A material and immediately
A is rapidly cooled and solidified while applying a pressure of kg/cd.
A composite material consisting of C8A, anatase type titanium oxide fiber, and potassium titanate fiber was manufactured.

Note that the fiber content of the composite material is between the preform and the path, and the same applies to the following examples and comparative examples.

Comparative Example 1 After dispersing the same potassium titanate fibers as in Example 1 in water,
After adding and mixing 5% by weight of colloidal silica based on the weight of the fibers, the mixture was filtered, pressurized, and dried at 80° C. to produce a preform having a fiber content of 30Vo and 1%. Thereafter, an AC8A/potassium titanate fiber composite material was manufactured under the same conditions as in Example 1.

Composite material JIS T obtained in Example 1 and Comparative Example 1
6 After heat treatment, a prismatic piece is cut out in the width direction of the preform using a cutting wheel, and a JI3 4 piece with threaded portions at both ends is cut out.
A test piece corresponding to No. 1 was prepared, and its tensile strength and elastic modulus at room temperature were measured.

Further, the coefficient of thermal expansion was measured using a TMA measuring device.

In the abrasion resistance test, a disk-shaped test piece with a diameter of 50 m + n and a thickness of 4 mm was prepared from each of the above composite materials, and after setting it on the rotary disk 3 of the test apparatus shown in Fig. 1, a test piece was placed on the top of the test piece. Place the mating material 2 and rotate the test piece 1 at a rotational speed of 380 rpm for 3 hours while applying a load F of 150 kg/cJ.
The amount of wear of each test piece was measured. The mating material 2 at this time had a shape as shown in FIG. 2, and two types of materials were used: SCr420m and chrome steel. Note that the notch in FIG. 2 is for fixing the movement of the mating member 2. The test results are shown in Figure 1. For comparison, this table also shows the physical property values for AC8A alone (Comparative Example 2).

No. table The symbols in the wear amount column are as follows.

Ds = Amount of wear on mating material (uses 5Cr420 steel as material)D
c: Amount of wear on mating material (hard chrome steel is used as material) C5:
Composite wear amount (when the mating material is S Cr420 steel) Cc:
Composite wear ff1 (when the mating material is hard chromium steel) As shown in Table 1, AC8A, a composite material made of anatase type titanium oxide fiber and potassium titanate fiber, is different from the conventional AC8A/potassium titanate fiber composite. The material has tensile strength, elastic modulus, and thermal expansion coefficient between the material and the road, and there is no particular difference in the amount of wear of the mating material between the two composite materials, but the amount of wear of the composite material is AC8A of the present invention, The composite material made of anatase titanium oxide fibers and potassium titanate fibers is significantly smaller. The Mohs hardness of anatase titanium oxide is said to be 5.5 to 6, but it is surprising that the wear resistance is significantly improved by filling a small amount of such a relatively soft material. It is thought that a reaction product between aluminum and aluminum light alloy components is involved in improving wear resistance, but this substance has not been identified at present.

Example 2 1400 g of anatase-type titanium oxide and 7 g of potassium carbonate
After dry mixing with 80g, put it in an alumina crucible,
Temperature increase rate 250℃/hour in electric furnace, holding temperature 900℃,
The temperature was lowered at a rate of 150° C./hour under the conditions of a holding time of 2 hours.

10. Place the baked product in a stainless steel container. After putting it in warm water of Q and soaking it for 4 hours, stirring was started at 400 rpm and the water temperature was adjusted to 60°C. Add 4N hydrochloric acid dropwise to adjust the pH to 1.
Adjusted to 0. After filtration, it was baked at 800°C for 1 hour.

This fiber was identified by X-ray diffraction and was found to be a single phase of rutile titanium oxide. Furthermore, when the fibers were observed using a scanning electron microscope, the average fiber length was 15 IEB.
The average fiber diameter was 0.4 un.

The above rutile type titanium oxide fiber 15Vo 1% and potassium titanate fiber (Titan Kogyo: HT-200) 85Vo
[4% based on the fiber weight after dispersing the mixture in water]
After adding and mixing colloidal silica in an amount of % by weight, the mixture was filtered and pressurized, and then dried at 80° C. to produce a preform having a fiber content of 25Vo1%. Next, about 600 pieces of the preform
After preheating to 250°C, place it in a mold, pour in molten JIS AC7B material at about 750°C, and immediately cool and solidify it while applying a pressure of 1000kg/cd. A composite material consisting of AC7B, rutile titanium oxide, and potassium titanate fibers was manufactured.

Comparative Example 3 Potassium titanate fiber (Titan Kogyo: HT-200)
After dispersing in water, 4% by weight of colloidal silica based on the fiber weight was added and mixed, filtered and pressurized, and then dried at 80° C. to produce a preform with a fiber content of 25Vo1%. Thereafter, an AC7B/potassium titanate fiber composite material was manufactured under the same conditions as in Example 2.

After subjecting the composite materials obtained in Example 2 and Comparative Example 3 to JIST4 heat treatment, strength, coefficient of thermal expansion, and abrasion resistance were measured in the same manner as in Example 1. The results are shown in Table 2. For comparison, this table also shows the case of AC7B alone (Comparative Example 4).

No. 2 table The symbols in the wear amount column are as follows.

Ds: Amount of wear on mating material (uses 5Cr420 steel as material)D
C: Amount of wear on mating material (Hard chrome steel is used as material) C8:
Composite wear amount (when the mating material is S Cr420 steel) Cc:
Composite wear amount (when the mating material is hard chromium steel) As is clear from Table 2, the composite material consisting of AC7B, rutile-type titanium oxide fiber, and potassium titanate fiber is lower than the conventional AC7
B/Potassium titanate fiber composite material has tensile strength, elastic modulus, and coefficient of thermal expansion between the paths, etc., and there is no particular difference in the amount of wear of the opposing material between the two composite materials, but the amount of wear of the composite material The wear amount of the composite material comprising AC7B, rutile titanium oxide fibers and potassium titanate fibers of the present invention is significantly smaller, and is less than 1/1000 of the wear amount of the conventional AC7B/potassium titanate fiber composite material.

Example 3 While stirring 2000 g of a hydrous titanium oxide slurry containing 10229.1% T and 1% SOs, 310 g of sodium carbonate powder was added. This slurry was spray-dried under conditions of an inlet temperature of 240 to 250°C and an outlet temperature of 90 to 100°C. Next, this dried product was placed in an alumina crucible and fired in an electric furnace at a heating rate of 200°C/hour, a firing temperature of 950°C, and a holding time of 3 hours.
The temperature was lowered at a rate of 0°C/hour.

After putting the baked product into 8g of warm water in a stainless steel container,
After stirring with a homomixer for 30 minutes, 24N sulfuric acid was added dropwise to adjust 9H to 1.2. After filtering and washing, it was baked at 850°C for 1 hour.

This fiber was identified by X-ray diffraction and was found to be a single phase of rutile titanium oxide. Further, when observed with a scanning electron microscope, it was found to be needle-shaped crystals with an average length of 4□□□ and an average diameter of 0.7 parts.

The above rutile type acicular titanium oxide 20Vo1% and Example 1
After dispersing in water a mixture consisting of 80Vo1% of potassium titanate fibers used in
A preform having a fiber content of 25Vo1% was produced. Next, after preheating the preform to about 600°C,
After preheating to 250℃ and placing it in a mold,
A molten metal of JIS standard ACIA material at about 720°C was poured and immediately cooled and solidified while applying a pressure of 1000 kg/ad to produce a composite material consisting of ACIA, rutile titanium oxide, and potassium titanate fibers.

Comparative Example 5 After dispersing the potassium titanate fibers used in Example 1 in water, adding and mixing 6% by weight of colloidal silica based on the fiber weight, filtering and pressurizing, drying at 80 ° C. A preform with a ratio of 25Vo1% was produced. Thereafter, an ACIA/potassium titanate am composite material was manufactured under the same conditions as in Example 3.

After subjecting the composite materials obtained in Example 3 and Comparative Example 5 to T6 heat treatment, strength, coefficient of thermal expansion, and abrasion resistance were measured in the same manner as in Example 1.

The results are shown in Table 3. For comparison, this table includes ACI
The case of A alone is also shown (Comparative Example 6).

No. 3 table The symbols of the wear shelf are as follows.

Ds: Amount of wear on mating material (S Cr420m is used as the material)
Dc: Amount of wear on mating material (hard chrome steel is used as material) C8
: Composite wear amount (when the mating material is S Cr420 steel) Cc
: Composite wear amount (when the mating material is hard chromium steel) As is clear from Table 3, the composite material made of ACIA, rutile type titanium oxide fiber, and potassium titanate fiber is less than the conventional AC
It has the same tensile strength, elastic modulus, and coefficient of thermal expansion as the IA/potassium titanate fiber composite material, and there is no particular difference in the amount of wear on the other material between the two composite materials, but the amount of wear on the composite material The composite material made of the ACIA of the present invention, rutile type titanium oxide fiber, and potassium titanate fiber is significantly smaller in terms of diameter.

Reference Example 1 In order to identify the reactants generated when combining light aluminum alloy and titanium oxide, anatase-type titanium oxide powder (KA-10 manufactured by Titan Kogyo) was pressure-molded using a press machine, and then the test was carried out. An AC8A/anatase type titanium oxide composite material was produced under the same conditions as in Example 1, and the composite material was
It was investigated using a line powder diffractometer. FIG. 1 shows the X-ray powder diffraction patterns of AC8A and AC8A/anatase type titanium oxide composite materials. As is clear from this figure, the X-ray powder diffraction pattern of the AC8A/anatase type titanium oxide composite material contains AC8
New diffraction lines other than those of the constituent components of A and anatase titanium oxide are observed.

In addition, when the Mohs hardness of the composite material was investigated, it was found to be 8 to 9.
showed the value of

The Mohs hardness of anatase-type titanium oxide is said to be 5.5 to 6, so the Mohs hardness of the reaction product generated when AC8A and anatase-type titanium oxide are combined is high, so the Mohs hardness of the composite material is high. It is judged that it has become.

[Effects of the Invention] The metal matrix composite material of the present invention has excellent mechanical properties such as wear resistance, strength, and dimensional stability, and is useful for piston wear-resistant rings, piston rings, bearings, vanes and rollers for rotary compressors, etc. Demonstrates effectiveness in sliding member applications such as

[Brief explanation of drawings]

Figure 1 is a diagram showing the results of X-ray powder diffraction intensity measurements of AC8A and AC8A/anatase type titanium oxide composite materials, Figure 2 is an explanatory diagram of the main parts showing the abrasion resistance test method, and Figure 3 is a diagram showing the results of the measurement of the X-ray powder diffraction intensity of AC8A and AC8A/anatase type titanium oxide composite materials. FIG. 1...Test piece 2...Mating material 3...
Turntable diagram 2

Claims (1)

[Claims] A sliding metal matrix composite material obtained by heat forming a mixture containing aluminum light alloy, titanium oxide, and potassium titanate fibers.