JPS59468B2 - High expansion porcelain composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to high expansion porcelain compositions that have good compatibility with high expansion objects such as metals, metal oxides and glasses.

Conventionally, it is known that ceramics are used in many electron tubes such as vacuum envelope tubes (see Japanese Patent Application Laid-Open No. 115164/1983), but the shapes are simple, such as cylinders or flat plates. Limited.

This is because the sintering shrinkage factor of ceramics reduces the finished dimensional accuracy of the parts, and in order to improve the finished dimensional accuracy, it is necessary to cause a certain amount of sintering shrinkage through sintering, and then grind it to the specified dimensions by rough sintering. It is necessary to use a complicated manufacturing method of tying the product.

Therefore, it has been difficult to use ceramics for products that have complex shapes and require mass production, such as the funnel portion of a television cathode ray tube.

However, since ceramics have superior mechanical strength and electrical insulation properties compared to glass, and also have less adsorbed gas, it has been proposed to use ceramic funnels, which are superior in terms of safety and reliability.

(For example, JP-A No. 52-99064, same No. 115164)
No., same No. 115657, same No. 115659, same No. 1
No. 24854, same No. 124855, same No. 126163
(Refer to No. 152155, etc.) In particular, a material containing one or two of forsterite, steatite, titania, and alumina and having a coefficient of thermal expansion that is the same as or similar to that of the glass of the panel, e.g. 84 to 99 (XIO-7) It is known to form a funnel part using ceramics.

(Refer to Japanese Unexamined Patent Publication No. 52-115164) Similar to such known techniques, the present invention aims to provide a highly expansible porcelain composition useful, for example, as a funnel part.

That is, in the first invention, the raw material composition is 35 to 55% by weight of calcium pyrophosphate and 14 to 37% by weight of calcium carbonate.
%, 5 to 35% of feldspar and sericite clay, and 5 to 40% of kaolinic clay, in which CaO, /P2O5
The weight ratio of is 12 to 15, and the essential components are 5IO2,A
g2O3, P2O5, CaO2MgO, 20 and N
It is made of a2O, and the expansion coefficient of porcelain is 85 to 120 (X1
0-7) (40 to 400°C).

And, in the second invention, the calcium pyrophosphate is Ca
Calcium phosphates with HPO4, less than 12, such as calcium hydrogen phosphate trihydrate (CaHPO, 2H2
0] Calcium hydrogen phosphate (CaHPO4),]] Calcium phosphate - hydrate CaH2PO4) 2.H20],
Calcium metaphosphate (Ca(PO3)2,1, calcium phosphate CCa3(PO,)2), hydroxyapatite CCa5(PO4)3(OH)), bone phosphorus, bone ash, etc. are substituted.

Calcium carbonate may also be replaced with calcium- and magnesium-containing minerals such as limestone or dolomite.

The composition of the present invention is characterized in that, first, by keeping the weight ratio of CaO/P2O5 constant, the amount of calcium phosphate blended and the coefficient of expansion of the porcelain exhibit a constant linear relationship.

FIG. 1 is an example of this, and shows that the relationship between the amount of calcium pyrophosphate and the expansion coefficient of porcelain in the case of CaHPO4.about.1.4 is linear.

Therefore, for example, if a material with an expansion coefficient suitable for a funnel portion is to be manufactured in the range of 85 to 120 (XIO-7) [40 to 400°C], the amount of calcium pyrophosphate may be appropriately selected.

Secondly, when porcelain having an arbitrary expansion coefficient is manufactured according to the above-mentioned first feature, various physical property values other than the expansion coefficient do not change significantly, as shown in Examples described later.

Thirdly, the porcelain made of the present composition has superior physical properties when compared with general silicate alumina porcelain.

Next, details of the composition of each material in the present invention will be explained.The expansion coefficient of porcelain is 85 to 120 (X
10-7) (40 to 4000C) because below 85 it is difficult to say that the expansion is high, and above 120 is the upper limit for stably obtaining the base material obtained by this method.

Calcium pyrophosphate reacts with CaO component to form tricalcium phosphate (Ca3(PO,)2), which is the main component of porcelain.
It is involved in the generation of

From the relationship shown in Figure 1, the expansion coefficient of porcelain is 85
~120 (X 10'-7) [: 40-400'C
) The amount required for the conditions is 35 to 55%.

In addition, calcium phosphates other than calcium pyrophosphate in the second invention with a CaO/P2O5 ratio of less than 1.2 are easily tricalcium phosphate CCa3 in porcelain by reaction with the CaO component and kaolinic clay described below.
(PO4)2] is generated.

Therefore, calcium hydrogen phosphate trihydrate [CaHPO
4.2H20], calcium hydrogen phosphate CCaHPO4
), calcium phosphate-hydrate CCa(H2PO4)2
・H2O), calcium metaphosphate [Ca(PO3)2
], tricalcium phosphate (Ca3 (PO4) 2 )
Hydroxyapatite (Ca5(po,)3(oH)) bone phosphorus,
Bone ash or the like can be used as a substitute in an amount corresponding to the amount equivalent to the phosphoric acid component of the above-mentioned calcium pyrophosphate.

Calcium carbonate has a Cab/P205=1.2-1.
If the range of condition 5 is used as a standard, a range of 14 to 37% is inevitably required.

This calcium carbonate reacts with calcium phosphate to participate in the production of tricalcium phosphate (Ca3 (PO4) 2 :), and at the same time reacts with kaolinic clay to participate in sintering of the composition.

The above CaO/P205 = 1 to obtain sintered porcelain
．． Conditions 2 to 15 apply.

When CaO/P2O5 is less than 12, the glass component of the sintered porcelain becomes excessive and a porcelain structure cannot be stably obtained.When it exceeds 15, the CaO component becomes excessive and the sinterability worsens, while at the same time the coefficient of expansion becomes unstable. I can't get it.

Although there is a risk that the magnesium oxide component may interfere with the production of tricalcium phosphate or may not show a stable relationship, as a sintering aid it can achieve the same effect as the CaO component, so the amount of CaO component added is Ca within 10% of
It is possible to place it with O.

Feldspar and sericite clay supply 20& and Na2O components behind the essential components and are essential components for porcelain formation of the composition.

If the blending amount is less than 5%, the desired effect cannot be obtained, and 35
% or more, the effect becomes excessive and becomes impractical.

The relationship between feldspar and sericite is interchangeable in that the firing temperature can be selected arbitrarily.

Kaolin clay is a component** that controls the moldability of the composition, and if it is less than 5%, it is not effective even in press molding.
Furthermore, no effect can be obtained in the reaction with the above-mentioned calcium phosphate and CaO component.

Moreover, if it exceeds 40%, the moldability becomes poor even in the case of slurry casting, resulting in excessive content.

The composition of the present invention is made into porcelain at a temperature of 1,200 to 1,350°C.

The mineral composition of the porcelain is mainly composed of a Ca3(PO4)2 crystal phase and a silicate alumina glass phase, and may sometimes contain trace amounts of anorthite and mullite.

Next, examples and test results will be shown.

As is clear from the table above, according to the present invention, it is possible to obtain porcelain that has high expansibility, has little change in physical property values, and has superior physical property values compared to general silicate alumina porcelain. It is useful as a material for industrial use.

In addition, in the above example, calcium pyrophosphate was used.
However, even when this was replaced with the above-mentioned calcium phosphate in the second invention, substantially the same results were obtained.

[Brief explanation of the drawing]

Figure 1 is a graph showing the relationship between the amount of calcium pyrophosphate and the expansion coefficient of porcelain.

Claims (1)

[Scope of Claims] 1 Raw material composition is calcium pyrophosphate 35 to 5% by weight
5%, calcium carbonate 14-37%, feldspar and sericite clay 5-35%, kaolin clay 5-40%, and the weight ratio of CaO/P2O5 in these components is 1.2-15.
and the essential components are S102, Al2O3, P2O5
, Cab, consisting of MgO1 and Na20,
The expansion coefficient of porcelain is 85 to 120 (X10-7)l'-4
A high expansion porcelain composition characterized in that the temperature is 0 to 400°C. 2 Calcium hydrogen phosphate trihydrate, calcium hydrogen phosphate, calcium phosphate hydrate, calcium metaphosphate, tricalcium phosphate, hydroxyapatite, bone phosphorus, bone ash with a raw material composition of less than 12 in weight percent CaO/P2O5 Calcium phosphates such as 35-55%, calcium carbonate 14-37%, feldspar and sericite clays 5-35%,
Consisting of 5 to 40% kaolin clay, CaO/
The weight ratio of P2O5 is 1.2 to 15, and the essential component is S.
i O2, Al2O3, P2O5, Cab, MgO
, is composed of 2O and Na20, and the expansion coefficient of porcelain is 8.
5 to 120 (X10-7) "40 to 400° C." A high expansion porcelain composition.