JPH02188473A - Production of ceramic composite material - Google Patents

Abstract

PURPOSE:To prevent the damage and embrittlement of a ceramic composite material due to the reaction of the reinforcing fibers with the matrix, to render superior strength and toughness and to utilize the material for automotive engine parts, etc., by impregnating ceramic fibers preheated to a specified temp. with an oxidized compd. of Ti and Cu melted by heating and by rapidly cooling them. CONSTITUTION:An oxidized compd. of Ti and Cu is melted by heating and ceramic fibers or whiskers are preheated to >=800 deg.C, preferably to the m.p. of the compd. or above and impregnated with the molten compd. in several sec to several min by pouring, dipping or other method. They are rapidly cooled to <=900 deg.C and slowly cooled to obtain a ceramic composite material using the oxidized compd. of Ti and Cu as the matrix.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method of manufacturing a ceramic composite material reinforced with ceramic fibers.

[Conventional technology]

Regarding composite materials with a matrix of titanium and copper oxide compounds, Japanese Patent Laid-Open No. 156972/1983 proposed a ceramic composite material in which reinforcing fibers such as alumina fibers were integrally embedded in a titanate steel matrix. There is only one.

According to the above publication, this ceramic composite material is CuO
After heating a mixture of and TiO to 1000-1050C to obtain titanate steel, water and a dispersant are added to this titanate steel to form a slurry, and this slurry is mixed with alumina (A/O
) It is manufactured by impregnating reinforcing fibers such as tlA fibers and heating them in the atmosphere to melt and impregnate titanate steel.

However, titanium and copper oxide compounds such as titanate steel are extremely reactive, so if you try to heat them to form a composite with, for example, AIO fibers, the reaction will proceed immediately.
Since the O fibers are lost or damaged and become brittle, it has not been possible to obtain a ceramic composite with high strength and high toughness suitable as a structural ceramic material.

[Problem to be solved by the invention]

Oxidized compounds of titanium and copper, such as titanate steel, have good wettability with ceramics and have the potential to be easily composited with ceramic fibers.

However, on the other hand, the oxidized compounds of titanium and steel are highly reactive;
Since it reacts when it comes into contact with ceramic fibers such as alumina fibers, when the two are combined, the ceramic fibers react in a short period of time, causing them to disappear, be damaged, or become brittle.

Therefore, in the above-mentioned conventional technology, a sample of silver titanate and ceramic fibers is heated at 1100 C during compositing.
It usually takes several hours to heat the sample to a certain degree and soak it up to the inside of the sample, and during this time it is inevitable that the ceramic fibers will react with the silver titanate and become damaged or brittle, so the ceramic fibers will be strengthened. It does not function well as a fiber,
Only ceramic composites with low strength and toughness were obtained.

In view of such conventional circumstances, an object of the present invention is to provide a method for suppressing the reaction between a titanium and copper oxide compound and ceramic fibers and manufacturing a ceramic composite having excellent strength and toughness.

[Means to solve the problem]

In order to achieve the above object, in the method for manufacturing a ceramic composite material of the present invention, ceramic fibers or whiskers preheated to 800C or higher are impregnated with a heat-molten titanium and copper oxide compound for several seconds to several minutes, and then It is characterized by immediate rapid cooling to a temperature of 900C or less.

In the present invention, the titanium and steel oxide compound refers to TiG
It refers to a compound obtained by heating T1o2 and OuO and/or CuO to 1000 tZ' or more, such as silver titanate, which is a compound of OuO and CuO.

Furthermore, the composition of the ceramic fibers or whiskers is not limited, and these may be used as fibers or whiskers, but
It is also possible to use a preformed product such as a woven fabric or a pressure molded product.

[Effect]

In order to suppress the reaction between the titanium and copper oxide compound and the ceramic fibers or whiskers, the method of the invention takes a solution to shorten the heat treatment time for composite formation.

In other words, in order to compound a sample of silver titanate and ceramic fibers by heating them to about 1100 r as in the past, it usually takes several hours to soak the inside of the sample, so there is no reaction during that time. It progresses. Therefore, in the method of the present invention, ceramic fibers or whiskers are directly impregnated with an oxidized compound of titanium and copper in a molten state to form a composite.

However, when a titanium and copper oxide compound heated and melted at 1000C or higher is brought into contact with ceramic fibers or whiskers at room temperature, the titanium and copper oxide compound solidifies and impregnates the surface of the ceramic fiber, fiber, or whisker upon contact. Since the channels are buried, it becomes difficult to impregnate the inside, and only a low-density composite with unimpregnated parts remaining inside can be obtained.

To solve this problem, in the method of the present invention, the ceramic fibers or whiskers are preheated to a temperature above 800C, preferably above the melting temperature of the titanium and copper oxide compound. That is, the fiber or whisker itself is placed in a mold, or its preform is preheated to the above temperature, and a molten titanium and copper oxide compound is poured into it or impregnated by dipping. Ceramic fiber etc. 5o
If the oxide compound of molten titanium and copper is preheated to a temperature above or above, it can easily penetrate into the interior without solidifying even if it comes into contact with it, and in an extremely short time compared to conventional methods, specifically from several seconds to several minutes. This completes the impregnation and compositing process to the inside. As a result, the reaction between the titanium and copper oxide compound and the ceramic fibers or whiskers can be effectively suppressed. In addition, after impregnating ceramic fibers or whiskers with titanium and copper oxide compounds in a short period of time,
If the mixture is cooled to room temperature over a long period of time, the reaction between the two will proceed during cooling, so it is necessary to rapidly cool the mixture to a temperature at which the reaction is suppressed, specifically to 900C or lower. If the temperature is below the above temperature, there is no risk of damage or embrittlement of the ceramic fibers or whiskers due to the reaction, but if the temperature is rapidly cooled, there is a risk that the ceramic fibers or whiskers will be damaged by thermal shock. Cool down.

〔Example〕

Example 1 40 g of continuous fiber woven fabric of ceramics containing 80% or more of klO was laminated in a mold made of a heat-resistant alloy.
Preheated at r for 1 hour. Next, 345 g of a mixture of TlO2 and OuO at a molar ratio of 1:3 was heated to 1050° C. to melt it, and poured into the mold preheated to the same temperature to impregnate the woven fabric. The time required for this impregnation composite was only 3.
It was 0 seconds. Thereafter, it was immediately rapidly cooled to 800C in 5 minutes, and then slowly cooled to room temperature.

When the obtained composite material was observed under an electron microscope, the ceramic continuous fibers were observed in perfect form, confirming that the reaction had not proceeded. Furthermore, the composite material is 3X4
When processed into a test piece of X40 mm and measured for four-point bending strength at room temperature and fracture toughness value (K) by the indentation method, the strength C was 49φm and the fracture toughness value was 9.5 MN7'm"/2
A high value was obtained.

Example 2 TiO:CuO:CuO was mixed at a molar ratio of 11:1, melted and reacted at 1100 C, and the obtained T1 and Higashi oxide compounds were ground and adjusted to an average particle size of 3.0 μm. . On the other hand, SIC whiskers (average diameter 1.5 μm x average length 25 μm) were used as a compact with a porosity of 65%, and 1050
Preheated at C for 30 minutes. Next, the preheated powder compact 75
g was dipped in the above-mentioned oxidized compound of T1 and Cu heated and melted at <1050 C to form an impregnated composite. The time required for this impregnation and composite formation was only 20 seconds. Immediately after the impregnation and composite formation, the mixture was rapidly cooled to 800C for 10 minutes, and then slowly cooled to room temperature.

For comparison, the oxidized compound of T1 and Cu synthesized as described above and SiC whiskers were mixed in a ball mill, and the green compact of the mixture was heated at 10 C/min and held at 1050 C for 30 minutes to form a composite. Thereafter, it was slowly cooled to obtain a composite material of a comparative example.

For each composite material, the X-ray diffraction peaks of the S1C whiskers before and after the composite heat treatment were measured using the X-ray diffraction method, and the X-ray diffraction peak ratio (where the value before heat treatment was taken as 100)
For the present invention example, T1 after impregnation (corrected for the increase in the oxidized compound of u) was determined. In addition, the mechanical properties of each of the obtained composite materials were evaluated in the same manner as in Example 1, and the results are summarized below.

Therefore, it is extremely useful in the field of structural ceramic materials such as automobile engine parts, which have not been widely applied in the past.

In the example of the present invention, the X-ray diffraction peak ratio is close to 100, and the SiC whisker hardly reacts before and after compounding.
Therefore, it can be seen that excellent values for both strength and fracture toughness were obtained.

〔Effect of the invention〕

According to the present invention, since compositing can be completed in a short time,
Ceramic fibers, which are reinforcing fibers, do not react with the oxidized compound of titanium and copper, which is a matrix, and are not damaged or become brittle, making it possible to easily produce a ceramic composite material with excellent strength and toughness.

Claims (2)

[Claims] (1) Ceramics characterized by impregnating ceramic fibers or whiskers preheated to 800°C or higher with a heated and molten titanium and copper oxide compound for several seconds to several minutes, and then immediately rapidly cooling to a temperature of 900°C or lower. Method of manufacturing composite materials. (2) A method for producing a ceramic composite material according to claim (1), characterized in that the material is rapidly cooled to a temperature of 900° C. or less and then slowly cooled.