JPS63282131A - Production of whisker-reinforced glass - Google Patents

Abstract

PURPOSE:To obtain the title high-strength glass without any crack and capable of easily providing a large bulky molded product by mixing whiskers and glass powder into a silica sol with the viscosity adjusted, converting the sol into a wet gel, heating the wet gel, and sintering the dry gel in an inert atmosphere. CONSTITUTION:Orthosilicic acid is hydrolyzed with water and/or ethanol, etc., to obtain a silica sol contg. >=20wt.% colloidal SiO2, an aq. acidic soln. of HC, etc., or an aq. soln. of NaC, etc., is added to the sol to regulate the pH, and 5-45vol.% whiskers of SiC, Si3N4, Al2O3, C, etc., and 5-70vol.% glass powder contg. >=45wt.% SiO2 having 3-200mu particle diameter are mixed into the sol when the viscosity reaches 0.05-2.0 poise to convert the sol into a wet gel. The wet gel is then slowly heated at a rate of 10-100 deg.C/day, and the obtained dry gel composite is sintered, for example, in an inert atmosphere of gaseous N2, etc., under high pressure or under the high temp. of 1,550 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for manufacturing whisker tempered glass.

[Conventional technology]

Composite materials made of glass reinforced with whiskers have an elastic modulus of 9 and strength compared to materials made only of glass.

It is attracting attention in various fields because it improves mechanical properties such as fracture toughness and thermal properties such as coefficient of thermal expansion and thermal conductivity.

As a method of manufacturing such composite materials.

A commonly used method is to mix rice powder and glass powder and then hot press the mixture. For example, publications (Fra
nk D, GBc et al. Performance of
Commercial and Reae4rch G
rade SiOWhiskersin a Boro
silicate Glass Matrix “Ce”
ramic engineering and 5ci
ence ProceedingsVo7? ,7. C
7-8], (1986), PP978-982) describes a method for producing 91G whisker-reinforced glass by mixing whiskers and glass powder using a ball mill method and hot pressing the mixture. However, such conventional methods have drawbacks as described below.

That is, in the conventional method described above, the whiskers tend to be damaged in the process of mixing the whiskers and the glass powder (therefore, the whiskers have the disadvantage that the original characteristics of the whiskers cannot be exhibited in the matrix after compositing.

Recently, in order to prevent damage to the reinforcement, i.e. whiskers, which occurs during the manufacturing process.

Attempts have also been made to produce whisker-reinforced ceramics using the sol Φ-gel method. For example, publications (J,
J, L51nnutti and D, R,01ark
Report on “Sol-Gem Deired Coa”
tings On 5iCand 5ilicate
Ceramic Engineer
ingand ScienceProceedings
, Voll, 5, [7-8].

1 (1986), PP574-582), SiC whiskers and Al2O2 were
) method, and it is possible to easily produce whisker-reinforced glass by using 5lo2 instead of hz2o5 as the raw material for the sol.

[Problem that the invention seeks to solve]

In the method using the above-mentioned sol-gel method, the sol shrinks significantly during the process in which the sol solution containing whiskers passes through the wet gel complex and becomes a dry gel. ) When using 4), the volume shrinks by several tens of percent, creating a large tensile stress between the non-shrinking whiskers and creating a crank in the glass strings. It had the fatal drawback of not being able to produce composite materials.

This invention was made to solve this problem, and minimizes damage to the whiskers.

The purpose of the present invention is to provide a method for manufacturing whisker-strengthened glass that has a high strengthening effect (and can easily produce large bulk molded products).

[Means for solving problems]

A method for manufacturing whisker tempered glass according to the present invention.

A viscosity adjustment step to adjust the viscosity of the silica sol to 0.05 to 2.0 poise, resulting in a viscosity-adjusted silica sol.

Mixing process to mix whiskers and glass powder.

Wet gelling process that turns the mixed liquid into a wet gel.

A dry gelling process in which the wet gel is heated to obtain a dry gel composite, and a sintering process in which the dry gel composite is sintered in an inert atmosphere are performed.

[Effect]

In this invention, whiskers, which are reinforcing materials, and glass powder, which will become part of the matrix, are simultaneously added to a silica sol liquid in a low viscosity sol state.

Mixing and stirring to disperse the whiskers can minimize whisker damage. By adding the glass powder, it is possible to reduce the shrinkage rate during the process of drying the silica sol solution containing whiskers and glass powder from wet glue to dry glue. Together with the added whiskers, they also have the effect of strengthening the dry gel itself, making it possible to obtain a dry gel composite that does not contain cranks, and also to prevent cracks from forming in large composites. It has an effect that lasts until the final sintering process, and it is also possible to easily produce large pulg-shaped molded bodies of whisker-reinforced glass with excellent mechanical properties.

〔Example〕

FIG. 1 is a process diagram showing the steps of a method for manufacturing whisker-strengthened glass according to an embodiment of the present invention.

The silica sol liquid according to the present invention preferably contains 20% by weight or more of a silica component.

The silica sol used is one in which orthosilicic acid (H2S10a) is hydrolyzed with water, ethanol, isopropanol, ethyl cellosolve, or a mixture of these alcohols, and the solution contains 8102 in colloidal form. Alternatively, a product obtained by partially hydrolyzing the orthosilicic acid to remove 40% by weight of the silica component in the aqueous solution and hydrolyzing it by the above method so that the aqueous solution contains colloidal particles of 8102 may be used. Furthermore, a colloidal silica aqueous solution prepared in such a manner that the aqueous solution contains colloidal silica may be used. An aqueous solution containing such colloidal silica is available from DuPont in the United States, for example.
A product commercially available under the trade name ucLox■ may be used.

As the colloidal silica aqueous solution for mixing the whiskers and the glass powder, the silica sol solution containing the hydrolyzed colloidal silica mentioned above or the colloidal silica aqueous solution sold by DuPont and others may be used as is, but the whiskers and the glass powder In order to obtain a uniform dispersion or to adjust the gelation rate, an acidic aqueous solution such as HCI or H2SO4, hydrochloric acid such as NaCAT, or an aqueous solution thereof is further added to the aqueous solution containing colloidal silica. be adjusted. At this time, the concentration of the aqueous solution of acid and salt and the amount added to the aqueous solution containing colloidal silica are appropriately determined in consideration of the temperature during production and gelation time.

The viscosity of the aqueous sol solution of colloidal silica is 0.05 to 2.
When the poise is preferably in the range of 0.1 to 1.0 poise, whiskers and glass powder are added to the colloidal silica sol solution and mixed and stirred.

At this time, in order to improve the wettability between rice car and colloidal silica sol, an anionic or nonionic surfactant is added as a surfactant before or during the addition of whiskers and glass powder to the sol. It's okay to be. Further, when the silica sol liquid foams due to the addition of a surfactant, an antifoaming agent may be used at the same time. In addition,
When adding whiskers and glass powder to the colloidal silica sol solution, whiskers and glass powder may be added separately as long as the sol viscosity is in the range of 0.05 to 2.0 poise (in this case, Either the whiskers or the glass powder may be added first.The whiskers and the glass powder may also be added at the same time.

If the viscosity of the colloidal silica sol is 0.05 poise or less, it will take a long time to gel the sol after whiskers and glass powder are added, and the whiskers and glass powder will precipitate in the sol. Furthermore, if you continue to stir to prevent precipitation, the whiskers are likely to be damaged.Also, if the viscosity of the sol is 2.0 poise or more, a large force will be applied to the whiskers when mixing and stirring the whiskers and glass powder. This may cause the whiskers to break.

Therefore, the viscosity of the sol aqueous solution at the time of mixing the whiskers and the glass powder into the sol is preferably a low viscosity io of 0.5 to 2.0 poise, particularly a range of 0.1 to 1.0 poise.

Whisker iS used for reinforcement related to this invention
Any inorganic material such as iC, 5i3N4, Az2o3, carbon, etc. may be used (.

Two or more types of these inorganic whiskers may be combined. The total volume fraction of the whiskers in the glass matrix is desirably set between 5 and 45% by volume in the whisker-strengthened glass after final sintering. If the total volume fraction of whiskers is less than 5%, it is difficult to obtain a composite effect by adding whiskers. Also, the total volume ratio of whiskers is 4
If the whiskers exceed 5% in the glass matrix, contact between the whiskers will not occur, and it will be difficult to sufficiently combine the whiskers with the glass matrix in the final composite, resulting in the formation of minute pores. In addition, when the total volume of whiskers is large, a large amount of force is required to mix and stir the whiskers and glass powder added to the sol solution, making it difficult for the whiskers to be uniformly dispersed (
(The more the damage to the whiskers increases, the more the damage to the whiskers increases. Therefore, it is desirable that the total volume fraction of the whiskers in the glass matrix is set between 5% and 45%.

The glass powder according to this invention has an average particle size of 3 μm.
It is desirable to use a material with a diameter of m to 200 μm. When the average particle size of the glass powder is 200 μm or more, it is difficult to obtain uniform dispersion when mixing the whiskers and the glass powder because the size is large compared to the whiskers, and it may cause damage to the whiskers. When the average particle size of glass particles is 3 μm or less, uniform dispersion can be obtained when whiskers and sol are mixed together, but when converted to the volume of sol per unit volume, the total glass particle size is The extremely large surface area has a large effect on the reaction process of the sol-gel, which is the target of this invention, and makes it difficult to maintain a stable state of the sol solution suitable for mixing whiskers and glass powder. It will become more difficult and difficult to industrialize.

In addition, as the glass powder, amorphous and crystalline ones may be used (and the chemical composition is preferably Si).
A material containing 45% by weight or more of O2 is used. For example, powdered glasses include quartz glass, silicate glass, aluminosilicate glass, β-eucryptite, β-
Glue aluminosilicate glass such as spodumene, and cordierite (magnesium aluminosilicate glass) powder are used.

The amount of glass powder added to the colloidal silica sol solution is defined by the volume percentage of the added glass powder in the glass matrix in the whisker-reinforced glass finally obtained. Therefore, the volume fraction of the added glass powder is preferably 5% to 70%, regardless of the whisker volume fraction. When the volume ratio of glass powder is 5% or less, the effect of adding glass powder is obvious at the stage of drying the wet kale composite to obtain a dry gel. When the volume percentage of glass powder exceeds 70%, it is difficult to stir the colloidal silica sol containing whiskers and glass powder, and it is difficult to obtain uniform dispersion of whiskers (and it is difficult to prevent whisker damage). becomes.

The dry gelled composite according to the present invention obtained by the above method is sintered at a temperature at or below the temperature at which, for example, ordinary glass powder is sintered.

It is elaborated. For example, when sintering, use a real press.

Pressurized with a hot isostatic pressurization device, high temperature and high pressure? (In this case, densification is further promoted.)

This invention will be explained below with reference to Examples.

5isN4 whiskers and SiC whiskers manufactured by Tateho Chemical Co., Ltd. were used as reinforcing materials.
~5 μm, aspect ratio is 5-100. The sol is colloidal silica (Du
pon't LuaoFI'lS-4C1) was used. This colloidal silica has a temperature of 1.2 at 156°C.
9g/c! It has a density of I. The glass powder is 96% by weight silicate glass (Corning Company).

Code number 7913) with a particle size of 325 mesh or less was used.

Colloidal silica (Ludox”, HS-40)
ni o, o 1N.

An aqueous HCl solution was added at 20°C, and when the viscosity of the aqueous solution of colloidal silica and HOA' reached 0.2 poise or more, whiskers and glass powder were added to the mixed aqueous solution and stirred thoroughly. At this time, the volume fraction of whiskers in the glass matrix of the whisker-reinforced glass composite structure finally obtained is 0.05. 0.1. 0.15
．． 0.2. 0.25. Adjust the weight percent of the whisker to be added so that it is 0.3, and the weight of the glass powder to be added so that the volume percent of the added glass powder to the total glass volume of the matrix is from zero (0) to 0.7. adjusted.

In order to obtain a wet gel containing whiskers by gelling a colloidal silica mixed aqueous solution containing whiskers and glass powder, the above mixed solution was placed in a water bath at 50°C with great care so as not to damage the whiskers. While stirring gently.

The gelation reaction of the colloidal silica solution was allowed to proceed until the viscosity of the mixed solution reached 1.0 poise.

After that, stirring of the mixed solution was stopped, and the mixed solution was
The temperature was gradually raised from 50°C to 180°C at a temperature increase rate of °C/hour to obtain a dry gel composite containing whiskers.

The temperature was gradually raised to suppress the occurrence of cranking, and a temperature of 10 to b is preferable.

The dry gel composite containing the whiskers was then sintered at a temperature of 1550° C. for 1 hour in an N2 atmosphere to obtain the final whisker-reinforced glass. Also.

A portion of the dry gel composite was hot pressed under a pressure of 1 to 9/- at a humidity of 1550°C to obtain the final whisker-strengthened glass.

FIG. 2 is a partial external view of a glass dreigle composite including whiskers before sintering according to an embodiment of the present invention. FIG. 2 shows a case where the composite contains 20% by volume of Si3N4 whiskers and the added volume% of glass powder is 20% with respect to the total glass matrix volume.

A composite was obtained in which no cranking occurred in the dry gel containing whiskers. Figure 3 shows the dry gel composite containing SiC whiskers shown in Figure 2 in a N2 atmosphere using TSS.

It is a scanning electron micrograph showing the structure of the fracture surface after a bending test piece was cut out from a piece sintered at a temperature of 1 hour at a temperature of 0.degree. C. and fractured by one bend.

The SIC whiskers are randomly and approximately uniformly distributed in three dimensions within the glass matrix.

Figure 4 shows the dry gel composite containing the 815N4 whiskers shown in Figure 2 at 1k at tsso℃ in N2 atmosphere.
This is an optical micrograph showing the microstructure of a cross section of a product hot-pressed under a pressure of 111 g/l. Si3N4 whiskers are two-dimensionally randomly arranged in a plane perpendicular to the pressing direction of the hot press.

In this way, the final sintering was performed using the hot press method51
Typical mechanical properties of SN4 Wiss-strengthened glass, such as strength and fracture toughness, were investigated. Figures 5 and 6 show the results of these measurements. In addition, the fifth
6 and 6 are a characteristic diagram showing the bending strength change depending on the whisker volume ratio and a characteristic diagram showing the change in the critical stress intensity factor depending on the whisker volume ratio of the whisker-strengthened glass according to the embodiment of the present invention, respectively. , (AI)~
(A6).

(B~(B6) shows the average value of the measurement results of the above characteristics of each of 15 test pieces of whisker-reinforced glass according to the example of this invention. Also, (X) and (Y) For comparison, the same measurement results as above are shown for a single glass matrix obtained in the same manner as in the examples of the present invention except that the whiskers of the present invention are not included. The whisker-strengthened glass according to the example shows far superior mechanical properties compared to glass without whisker reinforcement.

As explained above with reference to Examples, according to the Examples of the present invention, the total volume % of whiskers in the final composite material is in the range of 5% to 45% in W. If the volume fraction of the added glass powder to the total volume of the glass matrix in the final composite side is in the range of 5% to 70%, the formation of cracks containing whiskers in good condition (in the bulk dry gel composite) (and the whisker-containing dry gel composite thus obtained.

It was not confirmed that no cracking would occur even after sintering.

〔Effect of the invention〕

As explained above, the present invention is a viscosity adjustment process in which the viscosity of a silica sol liquid is adjusted to 0.05 to 2.0 poise.

A mixing step of mixing whiskers and glass powder into a viscosity-adjusted silica sol solution, a wet gelling step of turning the mixed solution into a wet gel, a dry gelling step of raising the temperature of the wet gel to obtain a dry gel composite, and a dry gelling step of forming a dry gel composite. To obtain a method for manufacturing whisker-strengthened glass that minimizes damage to whiskers, has a high strengthening effect, and can easily produce large bulk molded products by performing a sintering process in which the glass is sintered in an inert atmosphere. Can be done.

[Brief explanation of the drawing]

Claims (9)

[Claims] (1) A viscosity adjustment step to adjust the viscosity of the silica sol solution to 0.05 to 2.0 poise, a mixing step of mixing whiskers and glass powder into the viscosity-adjusted silica sol solution, and a wet gelling step of turning the mixed solution into a wet gel. A method for producing whisker-strengthened glass, which comprises: a dry gelling step of heating a wet gel to obtain a dry gel composite; and a sintering step of sintering the dry gel composite in an inert atmosphere. (2) The method for producing whisker-strengthened glass according to claim 1, wherein the silica sol contains 20% by weight or more of a silica component. (3) The method for producing whisker-strengthened glass according to claim 1 or 2, wherein the total volume ratio of whiskers to the whisker-strengthened glass is in the range of 5 to 45%. (4) Whiskers are SiC, Si_3N_4, Al_2
The method for producing whisker tempered glass according to any one of claims 1 to 3, wherein the whisker tempered glass is at least one of O_3 and carbon. (5) The method for producing tempered glass according to any one of claims 1 to 4, wherein the glass powder has an average particle size in the range of 3 to 200 μm. (6) The volume fraction of glass powder is 5% as a proportion to the glass matrix in the whisker-strengthened glass.
70% of the whisker tempered glass according to any one of claims 1 to 5. (7) A method for producing whisker-strengthened glass according to any one of claims 1 to 6, using glass having a composition containing 45% by weight or more of SiO_2 as glass powder. (8) The method for producing whisker-strengthened glass according to any one of claims 1 to 7, in which the mixed silica sol liquid is dry-gelled while gradually heating the mixed silica sol solution at a rate of 10 to 100°C/day. (9) A method for producing whisker-strengthened glass according to any one of claims 1 to 8, which comprises sintering the dry gelled composite at high temperature and high pressure.