JPH0818880B2 - High zirconia heat melting refractory - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a hot-melt refractory having high corrosion resistance, and more particularly to a high-zirconia hot-melt refractory suitable for a glass melting furnace.

[Prior Art] A heat-melting refractory material is usually obtained by pouring molten metal into which a refractory material having a predetermined composition is completely melted in an electric furnace into a mold having a predetermined shape, cooling to room temperature while keeping the temperature constant, and then re-solidifying. Thus, it is widely known as a high-grade refractory having a completely different structure and manufacturing method from a fired or unfired bonded refractory.

Among such heat-melting refractories, ZrO ₂ has excellent corrosion resistance against molten glass, etc., so high-zirconia heat-melting refractories containing about 90% ZrO ₂ are widely used as glass furnace refractories. It is used. However, because most of them are composed of ZrO ₂ (badellite) crystals in terms of structure, it is difficult to suppress the abnormal expansion and contraction around 1100 ° C, which is peculiar to ZrO ₂ , and as a block-shaped cast product without cracks. Is known not to be obtained.

Therefore, as a casting refractory containing ZrO _{2 of} about 90% or more, a method of adding SiO ₂ and other components has been disclosed in JP-B-47-15689 and JP-A-48-85610. Kaisho
No. 53-121012, Japanese Patent Publication No. 59-12619, and Japanese Patent Laid-Open No. 62-59576.

JP-B-47-15689 aims to stabilize ZrO ₂ by adding a rare earth oxide, and JP-A-48-85610 discloses that SiO ₂ , Al ₂ O
_3, CuO, was added B ₂ O _3, by forming a glassy phase at the grain boundaries of the ZrO _2, expansion of the ZrO _2, shrinkage and to absorb, likewise JP 53-121012, SiO _2, CaO, glassy phase MgO, SiO ₂ in _{JP-B-59-12619, Al 2 O 3, P} 2 glassy phase _{O 5, SiO 2, Al 2} O 3 in JP 62-59576 , by forming the P ₂ O _5, glassy phase B ₂ O _3, it has a ingot to take without cracking.

[Problems to be Solved by the Invention] In the conventional high-zirconia heat-melting refractory, a small amount of glassy phase is formed in the matrix in order to absorb expansion and contraction of ZrO _2. Since it is desirable, the main component of the glass matrix is SiO ₂
Other than that, additives are needed. For example, JP-A-48
-85610, CuO or B ₂ O ₃ is added, and the method disclosed in JP-A-53-53
-121012, CaO, MgO, in Japanese Patent Publication No. 59-12619,
P ₂ O ₅ and, in JP-A-62-59576, P ₂ O ₅ and B ₂ O ₃ are added. Among them, Japanese Patent Laid-Open No. 53-121012 discloses that the glass matrix component is composed of only SiO ₂ and CaO, MgO components, and the matrix glass phase inevitably becomes hard, which allows the ingot to be obtained without cracking. Is considered difficult.

In JP-A-48-85610, CuO is used as a matrix component.
Alternatively, B ₂ O ₃ is an essential component, but the Al ₂ O ₃ / SiO ₂ ratio is 0.
When it is 5 or more, it is said that the viscous phase of the vitreous phase is not sufficient and cracks cannot be sufficiently prevented. Also, CuO
When used as a glass kiln, there is a problem that the glass material is colored, and it is not suitable for applications such as soda lime-based glass, which does not like coloring.

In Japanese Examined Patent Publication No. 59-12619, by adding a P ₂ O ₅ component, by forming a so-called soft glass matrix, the Al ₂ O ₃ / SiO ₂ ratio is not limited to 0.5 or less It is made so as to obtain an ingot that does not have gravel on the glass or coloring even when used as a refractory for a glass melting furnace.

In JP-A-62-59576, an alkali metal oxide of 0.1% is used.
While maintaining the content below, by adding the P ₂ O ₅ and B ₂ O ₃ components, a so-called soft glass matrix is formed to obtain a crack-free ingot.

However, after that, JP-A-59-12619 and JP-A-62-595.
When using many of the components corresponding to No. 76 as lining bricks such as glass kilns, due to the difference in operating conditions such as heating conditions, in a relatively low temperature range of 400 to 600 ° C,
Occasionally, a phenomenon in which the brick surface was peeled off like a clam (hereinafter referred to as chip-off) was observed.

[Means for Solving Problems] In view of these points, the present invention has conventional extremely excellent corrosion resistance, and generates gravel on glass as a refractory for molten glass, or colors the dough. We have succeeded in producing crack-free high zirconia refractory that is not only a cast product but also can prevent the chip-off phenomenon in the relatively low temperature range of 400 to 600 ℃ during heating. It is a thing.

That is, according to the present invention, the chemical analysis value is ZrO ₂ in wt%.
85-97%, the SiO ₂ 2 to 10% of B ₂ O _{3 2%} or less, the Al ₂ O ₃ containing less than 3%, and, P ₂ O ₅ is 0.05 to 0.15%, alkali metal oxides ( high ZrO ₂ quality hot melt refractory characterized by containing R ₂ O) less than 1.0% 0.11% or more is intended to be subject matter.

The refractory of the present invention is required to be limited by a strict chemical analysis value for the reason described later, and as the refractory structure, the grain boundary of the coarse crystal of baddelite is P
_It has a dense and homogeneous structure filled with a small amount of a soft glass matrix component, with the ₂ O ₅ and B ₂ O ₃ components as important components.

Here, it is as follows when the gravimetric analysis value of this invention is described together with a preferable range. (weight%) Next, preferred ranges and reasons for each component will be described.

First, if ZrO ₂ is too small, high corrosion resistance cannot be achieved, but if it is too much and the glass matrix component is too small,
It is very difficult to obtain a block-shaped casting without cracks.

As a glass matrix component, P ₂ O ₅ has been found to bring about an effect as what can form a so-called soft glass matrix. Therefore, as a whole glass component, even a small amount of glass component is cracked. In addition to making it possible to obtain castings without
Even if the obtained casting is used as a refractory for a glass melting furnace, there is no fear of gravel generation or coloring on the glass. Further, the P ₂ O ₅ component has an advantage of reducing power consumption because it facilitates melting, and is an excellent additive as a high zirconia refractory additive.

B ₂ O ₃ is P ₂ O ₅ instead of the alkali metal oxide.
It has also been found to work in conjunction with to soften the glass matrix.

Here, as a result of investigating the chip-off phenomenon and P ₂ O ₅ , B ₂ O ₃ content at the time of heating, which is the main object of the present invention, the cause is unknown, but for the P ₂ O ₅ amount, 0.15% It was found that the above content occurred when it was contained, and it was found that it is necessary to suppress it to 0.15% or less in order to prevent the chip-off phenomenon. Further, when P ₂ O ₅ is too small, it is difficult to form a so-called soft glass matrix and it is difficult to produce a cast product without cracks, but here, another object of the invention is B ₂ O ₃ the addition of, because soft glass matrix cooperates with _{P 2 O 5, P 2 O} 5 is also in a small amount of 0.05%, without particular about the Al ₂ O ₃ / SiO ₂ ratio below 0.5 ingot Can be cast without cracks. However, if the content of B ₂ O ₃ is too large, it becomes difficult to obtain a dense cast product, so the required amount of B ₂ O ₃ is usually 2% or less, and it cooperates with P ₂ O _5. Since it works with 0.03
It should be ~ 0.2%. Speaking of SiO ₂ , at least 2% is necessary as a basic component forming a glass matrix, but if too much, it causes a decrease in corrosion resistance, so it is necessary to limit it to 10% or less, and preferably 6% or less. %
It is the following.

Al ₂ O ₃ is an essential component in the refractory material of the present invention, but if it is too much, it hardens the glass matrix and causes cracks. Therefore, the content is limited to less than 3%, preferably less than 1%. However, the Al ₂ O ₃ / SiO ₂ ratio is obtained by the effect of the addition of P ₂ O ₅ , particularly as shown in JP-A-48-85610, to obtain a crack-free ingot even if it is not limited to 0.5 or less. be able to.

The content of alkali metal oxides such as Na ₂ O and K ₂ O is 0.11% or more and less than 1%, preferably 0.11% or more and less than 0.6%.
In particular, it is preferable to limit the amount of alkaline earth metal oxides to the amount of impurities that are inevitably included in the raw materials. In any case, the total amount of alkali and alkaline earth metal oxides is preferably less than 1%, and less than 0.6% is the best.

[Examples] Examples of the present invention will be described below.

Baderite ore and ZrO ₂ raw materials such as desiliconized zirconia and P ₂
A batch mixture of O ₅ and B ₂ O ₃ raw materials adjusted to a predetermined amount was charged into a 500 kV single-phase electric arc furnace, and a melting temperature of 220
It melted completely at 0 to 2400 ° C. This hot water has an internal volume of 200 m / m x 3
It was poured into a graphite mold, which was surrounded by Bayer alumina around 00 m / m × 700 m / m, and cast, and then cooled to near room temperature.

The chemical analysis values and various properties of the obtained casting are shown in Table 1. (Samples P1 to P8 are for comparison.) [Effects of the Invention] As described above, the refractory material of the present invention is a conventional ZrO ₂
About 40% of the ZrO ₂ -Al ₂ O ₃ -SiO ₂ cast material can be obtained as a cast without cracks, with high corrosion resistance and high ZrO ₂ quality bricks. Depending on the raising conditions, it is possible to prevent the chip-off phenomenon that the brick surface sometimes peels off like a clam, and there is no fear of gravel on the glass from the brick scraping pieces due to chip-off, coloring, and as a refractory material for glass kilns. It's very good.

Claims (4)

[Claims] 1. As a chemical analysis value, 85 to 97% by weight of ZrO ₂ is used.
%, SiO ₂ is ₂ to 10%, B ₂ O ₃ is 2% or less, Al ₂ O ₃ is less than 3%, and P ₂ O ₅ is 0.05 to 0.15% and alkali metal oxide is 0.11% or more. A high-zirconia hot melt refractory material characterized by containing less than 1%. _2. The refractory material according to claim 1, wherein ZrO ₂ is 90 to 96% and SiO ₂ is 3 to 6%. 3. The refractory material according to claim 1 or 2, wherein B ₂ O ₃ is 0.03 to 0.2%. 4. The total amount of alkali metal oxides and alkaline earth oxides is less than 1%.
Refractory according to Item 3 or Item 3.