JPS61201679A - Lightweight heat resistant tray and manufacture - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a lightweight heat-resistant tray for firing thin plate-like molded products of ceramics, glass, and various metal oxides.

[Conventional technology]

In recent information, in the electronics industry, functional parts such as sensors, capacitors, and IC boards are transitioning to ceramics. Among them, fine ceramics such as alumina and silicon nitride, dielectric elements such as barium titanate, and magnetic materials such as composite oxides such as iron, barium, or strontium are considered promising. These ceramics and metal oxides have excellent properties such as electrical insulation, semiconductivity, heat resistance, wear resistance, high strength, and high magnetic force, and their uses will continue to expand in the future. After mixing raw materials, these functional parts are molded into various shapes by extrusion molding, injection molding, cast molding, press molding, etc., and then placed on a firing tray and fired to become a product. This firing tray uses mullite, alumina, zirconia, cordierite, silicon carbide, and silica refractories.

[Problem that the invention seeks to solve]

Conventionally, all of the trays for firing functional parts such as ceramics are formed by a method such as pressing, and then fired at a high temperature. However, conventionally used baking trays have a high bulk density, so a large amount of energy is required to heat them, and they are also heavy, so there is a limit to stacking them when baking in multiple stages. there were. Furthermore, it was difficult to make the temperature distribution uniform between the upper and lower stages in the furnace. Furthermore, if the firing speed was increased or the cooling/heating cycle was increased, the firing tray would crack, resulting in poor productivity. Furthermore, even if we tried to reduce the volume occupied by the baking tray in order to increase thermal efficiency by making the baking zone smaller, conventional baking trays could not be manufactured below a certain thickness due to problems such as warping. . On the other hand, lightweight molded products are known that are made by making a slurry of heat-resistant inorganic fibers such as ceramic fibers and an inorganic binder (for example, silica sol, clay, Sevioly, etc.) and a large amount of water and molding them using a wet papermaking method. However, this molded product does not have a smooth surface, and although the inorganic binder is filled between the lattices of the heat-resistant inorganic fibers, it falls off and becomes powder, making it unsuitable for use as a tray for firing precision ceramics. Met.

As described above, conventional heat-resistant firing trays are not unsuitable for firing precision ceramics because their energy costs and consumables costs account for a large portion of the product cost.

SUMMARY OF THE INVENTION In order to solve these drawbacks, it is an object of the present invention to provide a lightweight heat-resistant tray for firing precision ceramics that is energy-saving, lightweight, extremely thin, and excellent against thermal changes.

[Failure to solve the problem]

The lightweight heat-resistant tray of the present invention substantially contains three heat-resistant inorganic fibers.
5 to 85% by weight, 15 to 50% by weight of one or more refractory powders selected from alumina, alumina-silica, and zirconia, and silica-soda yarn, boric acid yarn, and silica yarn. It consists of 5 to 40% by weight of an easy-sintering aid selected from frit, and the total amount is 100% by weight.
The present invention relates to a lightweight tray for firing ceramics, which is formed by sintering and bonding the contact points of the inorganic fibers in a molded plate with a heat-resistant inorganic fiber and a material selected from alumina, alumina-silica, and zirconia. One or more types of refractory powder, an easy-to-burn auxiliary agent selected from silica-soda yarn, boric acid pneumatic yarn, and silica-based frit, and organic or inorganic molding auxiliary agents as necessary are mixed with water. heat-resistant inorganic fibers in terms of solid content.
5-85 heavy fi%, alumina, alumina-silica.

15-50% by weight of one or more types of refractory powder selected from zirconia materials and 5-40% by weight of an easy-to-burn auxiliary agent selected from silica-soda yarn, boric acid lucium yarn, and silica-based frit. , and water content 100-150% by weight
The present invention relates to a method for producing a lightweight heat-resistant tray for firing ceramics, which comprises forming a molded body, compressing the molded body, then drying it, and firing it at a temperature range of 1200 to 1500°C.

0 effect Conventionally, molded products made mainly of heat-resistant inorganic fibers are generally made into a slurry by mixing an inorganic binder such as colloidal phosphoric acid or/and an organic binder such as starch, and then agglomerated using a flocculant such as sulfuric acid. It is obtained by molding and drying using the papermaking method. However, since these molded products are unfired molded products, they may shrink when heated, become weaker if the organic binder is burnt out, and because the inorganic binder is not sintered, the inorganic fibers may soften. Large deformations often occurred during sintering or sintering.

Therefore, the present inventors investigated a method of sintering and bonding the joints of conventionally used inorganic heat-resistant fibers using an inorganic binder.
It has been found that by firing at a temperature of 0.degree. C., it is possible to obtain a tray for firing ceramics that is extremely lightweight and has a high strength and heat resistance that was previously unobtainable. The method will be explained in detail below.

At least one type of heat-resistant inorganic fiber used in the present invention is effective, such as silica-alumina fiber (hereinafter abbreviated as CF), alumina crystalline fiber (hereinafter abbreviated as AF), mullite crystallized fiber (hereinafter abbreviated as MF), etc. be. However, the non-fibrous materials in these heat-resistant inorganic fibers do not only reduce the smoothness of the surface of the molded product, but also add weight, so in order to obtain the lightweight heat-resistant tray of the present invention, the content must be 20% by weight or less. There is. Since these heat-resistant inorganic fibers are the main structure of the lightweight heat-resistant tray of the present invention, the fibers are at least 35 to 85
% by weight is necessary, and preferably 40 to 60% by weight is suitably selected.

If 35% by weight is ungrooved, the amount of inorganic binder will be relatively large, making it heavier and more likely to break. On the other hand, if it exceeds 85% by weight, the ratio of sintering and bonding the contact points of the fibers will decrease, and although the weight will be reduced, the strength will be low and deformation will occur.

In addition, the inorganic binder of the present invention is a refractory powder such as silica/alumina-based or alumia-based or zirconia-based clay, kaolin, alumina, or zirconia, feldspar, or boric acid.

It is also possible to use a combination of at least one kind of easy-to-burn auxiliary agents such as limestone, betalite, glass powder, and ridges. These inorganic binders are mixed in advance into a formulation that sinters at a predetermined temperature, and then the Bo! It is used after being ground to approximately 50 μm or less using a grinder such as Remill. As a result, the bonded portions of the heat-resistant inorganic fibers can be reliably sintered and bonded.

The heat-resistant inorganic fiber and the inorganic binder are conventionally kneaded or made into a slurry liquid and formed into a sheet by suction molding, pour molding, paper forming, etc., but preferably, a method of preparing a slurry liquid and forming it into a sheet by paper forming is preferable. desirable.

In order to improve the yield when forming a composition comprising the inorganic fibers and an inorganic binder, a flocculant such as general polyacrylamide thread or polybasic aluminum is added. Further, in order to improve the handling strength at room temperature, general organic binders such as starch and latex are suitable, and organic fibers such as pulp and hemp can also be used. If you want to create more interference, CM
It is also possible to add a small amount of a thickener such as C or sodium alginate.

The above composition is molded by a press molding method in which compression is approximately 30 to 6096 degrees using a flat plate having a hydraulic cylinder, and after drying, the molded product has a bulk density of 0.4 to 1.0. The light weight heat-resistant tray of the present invention can be obtained by baking at a temperature of 1200 to 1500°C for 2 hours or more in a heating furnace equipped with a heating element or burner, and after cooling.The baking temperature depends on the blending ratio of the inorganic binder. Although it can be changed arbitrarily, considering the temperature actually used for firing ceramics, at least 1200 tr or more is required, and preferably a firing temperature of 1400 to 1500° C. is economically suitable.

The lightweight heat-resistant tray of the present invention will be explained in detail in the following examples.

〔Example〕

Example 1 Calcined alumina powder 2251 and calcium borate 40J' were mixed and passed through a commercially available ball mill to pass through a 250-mesh standard sieve specified in JIS Z-8801, and this was used as an inorganic binder. To this inorganic binder, AF 4001 and 30 ml of acinitrile getadiene latex (4296 solution) were mixed and stirred in 20 μm of water. Then sulfuric acid band (10% solution) 2
4.

A slurry-like mixture was prepared by adding 1 liter of waste. This slurry liquid was transferred to a 35×40α rectangular paper making machine, and excess water was removed using a nutsch pump to obtain a molded plate with a thickness of about 10 g111. This molded plate was inserted into a hydraulic flat plate press and pressed at a pressure of 20 koji to form a molded product with a thickness of 6 JIB. The bulk density of the molded product after drying was 0.80 to 0.80. After polishing the surface of this molded body, it was placed in a furnace at 1400°C for 24 hours.
Time firing was performed. The physical properties of the obtained molded product were as shown in Table 1. Example 2 A mixture of calcined alumina 300, kaolin 185J', glass free, ) 115/ was pulverized and sorted in the same manner as in Example 1 to obtain an inorganic binder. Separately, CF4001 and cationized starch (2096 solution) were previously washed with water to reduce the non-fibrous content to 1896.
The mixture was mixed into a total of 20 μm of water and stirred. Next, a polyacrylamide flocculant (0.5% solution) was added and flocculated to form a slurry mixture. This slurry liquid was paper-formed and pressed in the same manner as in Example 1 to obtain a molded article with a thickness of 6 m. After the surface of this molded body was polished, it was fired in a furnace at 1300° C. for 24 hours. The physical properties of the obtained molded product were as shown in Table 1.

Example 3 Similar to Example 1, the inorganic binder was kaolin 110,
AF 200 J' as a crushed product of a mixture of quartz 607' and soda feldspar 95/CF200 used in Example 2
P and snalene butadiene rubber latex (solid content 42%
) 30'l/and 20! The mixture was mixed and stirred in water. Then polyacrylamide bath M (1596g liquid) 80a/
,! :200m of aluminum sulfate solution (10% solution)
The mixture was added to form a slurry-like mixture. From this slurry liquid, paper was made and pressed in the same manner as in Example 1 to obtain a thickness of 5.
A molded body of m was obtained. 1350℃ after surface polishing to this molded body
Firing was performed in a furnace for 24 hours. The physical properties of the obtained molded product were as shown in Table 1.

Example 4 Calcined alumina fine powder 2 was used as an inorganic binder in the same manner as in Example 1.
00 J', Kibushi clay 120P, boric acid lucium 8
The pulverized mixture of MF400 and cationized starch (2051) was mixed into 40d1r2 (l) of water and stirred.

Next, polyacrylamide flocculant 180d (0,5
96 solution) to form a slurry mixture, and the same procedure as in Example 1 was carried out to form a molded product with a thickness of 6 mm. The physical properties of this molded body after firing in a furnace at 1400° C. for 10 hours were as shown in Table 1.

Example 5 Similar to Example 1, kaolin 75J' was used as an inorganic binder,
CF4001 and 30d of nitrile butadiene latex (4296 solution) obtained in the same manner as in Example 2 using a mixed and pulverized mixture of montmorillonite 10P1 calcium borate 357' and 20! The mixture was dispersed in water and mixed and stirred. Then aluminum sulfate (109if
After adding 240 ml of liquid n) to form a slurry liquid, a 6 m molded body was obtained in the same manner as in Example 1. After firing this molded body in a furnace at 1350°C, a molded body having physical properties as shown in Table 1 was obtained.

[Comparative Example 1] 20 J' of methylcellulose powder and 120 J' of water were added to a mixture 2 consisting of 13% by weight of calcined alumina fine powder, 48% by weight of kaolin, and 39% by weight of talc, and thoroughly kneaded in a clay kneader. The kneaded product thus obtained was transferred into a mold previously made with Ceracola and press-molded to obtain a molded product having a thickness of iom after drying.

This molded product was heated in a furnace at 1350° C. for 24 hours and then slowly cooled to room temperature to obtain a baking tray. The physical properties of the molded article thus obtained were as shown in Table 1.

Table 1 Table 2 [Effects of the Invention] As described above, the tray obtained in Example 1, in which the surface of the lightweight heat-resistant tray was coated mainly with zirconia oxide, and the tray obtained in Comparative Example 1 were compared. An electronic ceramic part formed by hot pressing with Pariwam titanate as the main component and a small amount of organic binder added thereto was fired for 10 hours in an electric furnace with an internal furnace temperature of 1350°C. The results are shown in Table 2.

Similarly, an alumina substrate formed from a slurry made by adding a small amount of magnesia and an organic binder to alumina powder by the Doctor Plaid method was fired for 12 hours in an electric furnace at an internal temperature of 1400°C. The results are shown in Table 2. As a result, compared to conventional heat-resistant trays, the weight reduction increases the amount of baking per batch by 3.3 to 1.4 times. Furthermore, the amount of heat taken out by the tray itself is approximately 1.1%, which is effective for energy saving, and is approximately 1.1% per tray.
Since the product can be made 2.8 times as large, it is possible to reduce costs as a consumable item.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing the mixing state of the fibers and binder in a conventional heat-resistant fiber molded board, and FIG. 2 is a schematic diagram showing the bonding state of the fibers and binder in the molded board of the heat-resistant tray of the present invention. be. 1...Heat-resistant inorganic fiber

Claims (1)

[Claims] 1. Substantially 35 to 85% by weight of heat-resistant inorganic fibers and 15 to 50% by weight of one or more refractory powders selected from alumina, alumina-silica, and zirconia. The contacts of the inorganic fibers are sintered in a molded plate containing 5 to 40% by weight of an easy-sintering aid selected from silica/soda-based, calcium borate thread, and silica thread frit, and the total amount is 100% by weight. A lightweight tray for firing ceramics made by bonding. 2. Heat-resistant inorganic fibers, one or more refractory powders selected from alumina, alumina-silica, and zirconia, and easy-to-burn frits selected from silica-soda, calcium borate, and silica frits. The auxiliary agent and, if necessary, an organic or inorganic molding auxiliary agent are dispersed in water and molded to form a heat-resistant inorganic fiber of 35 to 85% by weight in terms of solid content, alumina, and alumina-silica. 15. One or more types of refractory powder selected from zirconia and zirconia.
~50% by weight and an easy-to-scorch aid selected from silica-soda, calcium borate, and silica frits 5 to 40% by weight
% by weight, and a water content of 100 to 150% by weight, the molded object was compressed, and then dried, and the moisture content was 100 to 150% by weight.
A method for manufacturing a lightweight heat-resistant tray for firing ceramics, characterized by firing at a temperature range of 500°C.