JPS6274034A - Production of fiber reinforced metal - Google Patents

Abstract

PURPOSE:To obtain a fiber reinforced metal in which reinforcing materials are uniformly distributed and which has excellent characteristics by using a mixture composed of a comps. which is consumed by heating and compsn. which is not consumed by the same aas a fibrous reinforcing material, forming the mixture by a binder diluted with a volatile solvent to a preform and filling a martix metal therein. CONSTITUTION:For example, K2O.6TiO2 fibers 1 are weighed into a vessel 2. A soln. prepd. by diluting sodium silicate as an inorg. binder and a soln. 4 prepd. by diluting a PVA with water or ethanol as an org. binder is added to the fibers 1. The above-mentioned mixture is thoroughly kneaded by a stirring rod 5 and further the mixture 9 which is made granular is calssified by using a sieve 8. The prescribed amt. of the classified mixture 9a is put into a molding tool 10 and the fibers 1 are compressively molded by the pressurizing force of a punch 11. After the molding is dried, the molding is heated to >=300 deg.C to decompose and consume the PVA, by which the preform 14 is obtd. The preform 14 is put into a metallic mold and molten Al is poured into the mold; thereafter, the molten alloy is pressurized by a punch. The molding is removed from the mold after cooling and the intended fiber reinforced metal is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for manufacturing a fiber-reinforced metal in which reinforcing materials such as fibers and whiskers are dispersed in a matrix metal.

[Conventional technology]

Various methods have been known for manufacturing fiber-reinforced metals, but high-pressure casting is the most practical method with high productivity. In this method, fibers and whiskers that serve as reinforcing materials are preformed using a binder so that they have a predetermined shape and content of reinforcing materials, and a metal such as aluminum that serves as a matrix is added to this preform in a molten state. The reinforcing material and matrix metal are composited by pressure impregnation. As the binder in this method, as disclosed in JP-A No. 57-1) 8855, a method using an organic compound binder (hereinafter referred to as organic binder) that can be eliminated by heating wax or the like; As disclosed in Japanese Unexamined Patent Publication No. 58-34150, a method using an inorganic compound binder (hereinafter referred to as inorganic binder) that does not disappear even when heated, such as water glass, is known.

[Problem that the invention seeks to solve]

By the way, fiber-reinforced metal is a metal material with excellent fracture resistance, low coefficient of thermal expansion, and wear resistance, but it is generally known that a lower content of reinforcing material is better in terms of wear resistance, for example. In addition, if you want to make the coefficient of thermal expansion slightly smaller than that of the matrix metal itself, or if the reinforcing fibers or whiskers are expensive, a preform with a low reinforcing material content is manufactured. There is a need.

When a preform with a low reinforcing material content as described above is molded using an organic binder, the strength to maintain the shape after the organic binder is heated and disappears after molding is very small, so it is difficult to apply compressive force during high-pressure casting. On the other hand, the predetermined shape is not maintained, making it impossible to uniformly disperse the reinforcing material.

In addition, when molding using an inorganic binder,
The binder must be diluted with water, etc., but when the preform is dried after forming, the diluent evaporates and moves to the surface of the preform, and this movement also causes the inorganic binder to move to the surface of the preform. As a result, the internal strength is extremely reduced and the shape cannot be maintained against compressive force during high-pressure casting. Furthermore, if a large amount of inorganic binder is used to prevent this, the strength properties of the fiber-reinforced metal itself will be significantly reduced because the inorganic binder will prevent the bonding of the reinforcing fibers or whiskers with the matrix metal. There was a problem of causing

[Means for solving problems]

Therefore, in order to solve the above-mentioned problems, the present invention involves mixing a composition that disappears by heating with a composition that does not disappear by heating, and then forming a preform using a binder obtained by diluting the mixture with a volatile solvent. This method employs a manufacturing method for fiber-reinforced metal.

[Effect]

According to the above means, even if the volatile solvent diluting the binder moves to the surface of the preform during drying, the inorganic binder is inhibited from moving to the surface of the preform due to the presence of the organic binder. Since the inorganic binder is almost uniformly present inside the preform even after drying, a preformed body that maintains almost uniform strength throughout the inside even if the organic binder is eliminated by heating is formed.

〔Effect of the invention〕

Therefore, the present invention has the excellent effect that a fiber-reinforced metal with excellent properties in which the reinforcing material is uniformly distributed can be manufactured with high productivity while maintaining the predetermined shape of the preform.

〔Example〕

The present invention will be explained in detail below based on embodiments shown in the drawings. FIG. 1 is a flowchart explaining the manufacturing method of fiber-reinforced metal of the present invention step by step, where l is potassium titanate fiber (K2O.6TiOz) weighed in a predetermined amount in a container 2, (average diameter 0.1 μm). , average length 20μ). Then, to this potassium titanate fiber 1, a solution 3 in which sodium silicate was diluted 5 to 20 times with water was added as an inorganic binder to 2 wt% of the potassium titanate fiber in terms of sodium silicate, and polyvinyl as an organic binder. Alcohol (PVA)
Solution 4, which was diluted 5 to 20 times with water or ethyl alcohol, was added in an amount of 3 wt % in terms of PVA per 1 fl:1 potassium titanate fiber. The reason for diluting the binder here is to ensure that the binder is uniformly dispersed and adhered to the potassium titanate thermal fibers 1.

Next, thoroughly knead this with a stirring rod 5.1. In order to further obtain a uniform preform, the granulated mixture 9 is classified using a sieve 8 having a mesh size of 30 mesh/inch.

A predetermined amount of the classified mixture 9a (passed through the sieve 8) is put into the mold 10 and punched 1) to give about 10 kg/
Compression molding was carried out under a pressure of - so that the volume content Vf of the potassium titanate fibers was 8%.

Next, this molded body 12 is demolded, and after being sufficiently dried in a drying oven 13 kept at 100 to 120°C, the furnace temperature is raised to 300°C or higher to decompose and eliminate PVA, thereby making the preformed body 12.
4 was manufactured.

Next, in order to composite this preform into potassium titanate fiber-reinforced aluminum, the preform is heated to approximately 500°C.
After pouring molten aluminum at 850-900℃ into a preheated mold, immediately punch it to 500k.
It could be produced by pressurizing at a pressure of g/aa or more, holding the pressure until it was sufficiently cooled, and then removing the pressure and demolding.

Table 1 shows the compressive strength and bending strength of preforms and potassium titanate fiber-reinforced aluminum produced by the method described above by varying the amounts of sodium silicate, an inorganic binder, and PVA, an organic binder. This shows the results of measuring strength.

As is clear from the margin table below, when using only sodium silicate, which is an inorganic binder, increasing the amount of binder improves the compressive strength of the preform, but the bending strength of the fiber reinforced metal does not improve much, and when the amount of inorganic binder increases. This suggests that the bond between the fibers and the matrix metal is inhibited. In addition, when using 2 and 4 t% of sodium silicate and 2 to 5 wt% of PVA, which is a mechanical binder, the compressive strength of the preform improves, and the bending strength of the fiber-reinforced metal also significantly improves. This is because, as already explained, even if the water diluting the binder moves to the surface of the preform during drying, the presence of PVA prevents the movement of sodium silicate to the surface of the preform. Even after drying, sodium silicate is almost uniformly present inside the interior, so PV is heated.
This is thought to be because even if A is eliminated, a preformed body is formed that maintains substantially uniform strength throughout the interior. When the amount of PVA reaches 7wt%, the bending strength of the fiber-reinforced metal decreases rapidly, but this is because amorphous carbon, which is converted by thermal decomposition of PVA, remains, similar to when a large amount of inorganic binder is used. This is thought to be because the bond between the fibers and the matrix metal is inhibited.

From the above results, the amount of inorganic binder used is 2 to 3 wt% of the fiber, which is a reinforcing material, and the amount of organic binder used is 2 to 3 wt% of the fiber, which is a reinforcing material.
It is concluded that 4 wt% is appropriate.

Tables 2 and 3 show the results of measuring the volume content, friction, and Pj wear characteristics of potassium titanate fiber-reinforced aluminum and StC whisker-reinforced aluminum produced by the method of the present invention.

As can be seen from Tables 2 and 3, the fiber-reinforced metal produced by the method of the present invention has a coefficient of friction at a volume content of 5 to 15%.

It can be seen that the amount of wear is small and the seizure load against cast iron CFCD70) is large, making it effective when applied to such low content fiber reinforced metals. The conditions for each experiment were: the seizure load was surface contact with cast iron (FCD70), and the circumferential speed was 2 m/see.

The load was increased every 10 kg every 30 seconds under oil lubrication, and the seizure load was determined when the friction coefficient exceeded 0.5.

In addition, the friction coefficient and wear amount were measured at 80 kg/kg using the same test equipment.
CD load, the former is from the rotational torque during the 30 minute test,
The latter was calculated by converting it into volume from the weight tjJ2 less after 30 minutes.

Reinforcing materials that can be applied in the present invention include SiC whiskers in addition to the above-mentioned potassium titanate fibers.

Si, N, whiskers, short carbon fiber.

There are fibers such as short fiber silica aluminum fibers, which can be effectively used for fiber-reinforced metals with a low volume content of Vf 5 to 15%.As matrix metals, in addition to aluminum, aluminum alloys, magnesium, zinc, lead,
Copper etc. can be used.

In addition, as a band which disappears by heating in the present invention, PV
In addition to A, polyacetal, polybutyral, wax,
In addition to sodium silicate, organic binders such as starch that do not disappear when heated include ethyl silicate,
Colloidal silica.

Inorganic binders made of silicates such as lithium silicate can be effectively used.

[Brief explanation of drawings]

FIG. 1 is a process diagram illustrating the method for manufacturing fiber-reinforced metal of the present invention. ■... Potassium titanate fiber, 3... Inorganic binder. 4... Organic binder, 14... Preformed body.

Claims (3)

[Claims] (1) A method for producing a fiber reinforced metal in which a reinforcing material in the form of fibers or whiskers is preformed using a binder and the preform is filled with a matrix metal, which comprises: a composition that disappears upon heating; 1. A method for producing a fiber-reinforced metal, which comprises forming a preform using a binder prepared by mixing a binder with a composition that does not disappear with a volatile solvent and diluting the binder with a volatile solvent. (2) Claims characterized in that the composition that disappears upon heating is 2 to 4 wt% based on the reinforcing material, and the composition that does not disappear upon heating is 2 to 3 wt% based on the reinforcing material. 2. The method for producing a fiber-reinforced metal according to item 1. (3) The method for producing a fiber-reinforced metal according to claim 1, wherein the volume content of the reinforcing material is 5 to 15%.