JP2017165631A - Zirconium composition and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a zirconium composition excellent in heat resistance when made as a refractory compared to a conventionally used aggregate derived from zircon sand and capable of being used as an aggregate having desired particle diameter and a manufacturing method therefor.SOLUTION: There is provided a zirconium composition containing 50 wt.% or more of zirconium oxide, 25 to 40 wt.% of silicon oxide and 0.1 to 1 wt.% of magnesium oxide based on the zirconium oxide and the silicon oxide, and having variation width of thermal expansion coefficient during a heat cycle with cooling to 30°C after increasing temperature from 30°C to 1500°C within 1.0%, variation width of thermal shrinkage within 1.2% and variation of the thermal expansion coefficient and thermal shrinkage with phase transition or zirconia of 0.2% or less in thermal behavior of a sintered body by molding at a pressure of 1.0 t/cmand burning at 1600°C.SELECTED DRAWING: None

Description

  The present invention relates to a zirconium-based composition mainly composed of zirconium oxide and silicon oxide having excellent thermal shock resistance and a method for producing the same.

Refractories are indispensable for the steel industry and are important components that affect the steelmaking process and cost. Since the refractory consumed in the steelmaking process occupies a large part of the total consumption, the improvement in quality and technology of the refractory directly leads to improvement in process efficiency and cost reduction.
In recent years, in the steelmaking process, the temperature of the molten steel is further increased and the residence time of the molten steel is increased, and the environment for using the refractory is becoming increasingly severe.

  On the other hand, zircon, which is a zirconium silicate ore, is used as a refractory raw material because it has low thermal expansion and is inexpensive. Zircon is generally present as sandy zircon sand having a particle size distribution of about 30 to 300 μm and an average particle size of about 100 μm, most of which is finely divided by pulverization. Yes. For this reason, when making the zircon aggregate used as a refractory raw material, the method of carrying out the sintering granulation of the pulverized zircon, such as a zircon flower, and grind | pulverizing is common. However, such a method increases the cost, and cannot meet various particle size demands as an aggregate as a core material of a refractory brick, and further, it is difficult to obtain a desired thermal shock resistance as a refractory. It has become.

  Patent Document 1 describes a composition obtained by adding a small amount of an oxide of an alkaline earth metal or an oxide of a transition metal to finely pulverized plasma dissociated zircon. Patent Document 1 also describes a composition in which magnesium oxide as an alkaline earth metal oxide as a sintering aid is mixed in an amount of 1 to 3% by weight with respect to plasma dissociated zircon. . However, since the zircon-containing composition described in Patent Document 1 is a mixed powder and fine particles, the function as an aggregate for which coarse particles are required is insufficient.

In Patent Document 2, a diameter of 10 mm or more and less than 50 mm of the same or similar composition as that of the base material with respect to 100 parts by weight of the base material consisting of 35 to 85 parts by weight of zircon, 11 to 65 parts by weight of silica, 3 to 10 parts by weight of clay and others. And 5 to 60 parts by weight of coarse aggregate particles, and 0.05 to 5.0 parts by weight of a siliceous chemical binder not containing Na ₂ O such as silica sol, amine silicate, and ethyl silicate in terms of solid SiO ₂ It describes an irregular refractory for molten metal containers. However, the amorphous refractory for a molten metal container described in Patent Document 2 lacks the function as an aggregate for which coarse particles are required, like the zircon-containing composition described in Patent Document 1.

Patent Document 3 discloses that 0.02 to 2.0% by weight of silica sol in terms of SiO ₂ and 0.08 to 2.0% of light-fired magnesia 0.005% with respect to 100% by weight of a refractory compound mainly composed of a zircon raw material. It describes a zircon-shaped amorphous refractory for casting construction to which 1.0% by weight is added. In addition, according to the description of Patent Document 3, such a zircon amorphous refractory for casting construction is made of Al ₂ O ₃ , CaO, MgO, Na ₂ O, etc. By reducing the components as much as possible, the hot strength is improved, and by giving appropriate fluidity and curability, the problem of a decrease in corrosion resistance due to a decrease in the hot strength can be eliminated. However, the above-mentioned zircon amorphous refractory does not yet have sufficient durability, and requires a production cost because it is necessary to add silica sol or the like.

JP 52-117912 A Japanese Patent Publication No. 4-020870 JP-A-6-157150

  As described above, zircon generally exists as sandy zircon sand having a particle size distribution of about 30 to 300 μm, and as a zircon refractory, a crushed product of zircon sand is usually used. .

  As a method of producing a zircon aggregate as a refractory raw material, in addition to the method of granulating and sintering the zircon pulverized product as described above and re-pulverizing it, in particular, as a method of producing a zircon aggregate having a large particle size, There is a method in which zircon sand is melted by an electromelting method, an ingot is produced, and the particle size is adjusted. When zircon is electrofused, the crystal phase is mainly a mixed phase of monoclinic zirconia and amorphous silica. Since silica is amorphous rather than quartz, rapid thermal expansion around 570 ° C. ( It is known that the phase transition of α quartz to β quartz can be suppressed. However, for zirconia, the volume change resulting from the phase transition to the monoclinic phase and the tetragonal phase cannot be suppressed even by rapid temperature rise, and the volume change becomes large. For this reason, when zirconia is present in the electrofused zircon aggregate, the thermal behavior as a refractory shows a thermal behavior different from that of zircon, resulting in inferior thermal cycle resistance and thermal shock resistance. Then, there is a problem that it is difficult to use as an aggregate. Moreover, since the synthesis | combination temperature of zircon is high, there also exists a subject that synthesis | combination costs.

  The present invention has been made in view of the above problems, and has superior heat resistance when used as a refractory and has a desired particle size as compared with a conventionally used zircon sand-derived aggregate. It is an object of the present invention to provide a zirconium-based composition that can be used as a method and a method for producing the same.

  As a result of intensive studies to solve the above-mentioned problems and achieve the object, the present inventors have added and mixed a magnesium compound to a raw material powder containing a zirconium compound and a silicon compound, melt-treated, By sizing, it was found that a zirconium-based composition serving as a raw material for a refractory exhibiting the same thermal behavior as zircon was obtained, and the present invention was completed.

That is, the present invention is as follows.
[1] A zirconium-based composition comprising 50 wt% or more of zirconium oxide, 25 to 40 wt% of silicon oxide, and 0.1 to 1 wt% of magnesium oxide based on zirconium oxide and silicon oxide. In the thermal behavior of the sintered body when molded at a pressure of 0 t / cm ² and fired at 1600 ° C., the coefficient of thermal expansion during the thermal cycle is raised from 30 ° C. to 1500 ° C. and then cooled to 30 ° C. The change width is within 1.0%, the change width of the thermal shrinkage rate is within 1.2%, and the change of the thermal expansion coefficient and the thermal shrinkage rate due to the phase transition of zirconia is 0.2% or less. A zirconium-based composition characterized by the above.
[2] The zirconium-based composition as described in [1] above, wherein 70% or more on a volume basis in the particle size distribution is 0.1 mm or more.
[3] A method for producing a zirconium-based composition as described in [1] or [2] above, wherein a mixing step of mixing a magnesium compound with a silicon compound and a zirconium compound or zirconium silicate, and the mixing step A method for producing a zirconium-based composition, comprising: a melting step for melting the mixed powder obtained in step 1 above a melting point; and a granulation step for cooling and sizing the melt obtained in the melting step .
[4] A refractory comprising the zirconium-based composition according to [1] or [2] as a raw material.
[5] A method for producing a refractory, comprising molding a powder containing the zirconium-based composition according to [1] or [2], and firing the molded body.

  According to the zirconium-based composition of the present invention, in addition to being able to synthesize zircon at a relatively low temperature, it exhibits thermal behavior close to that of zircon as compared with conventional aggregates derived from zircon sand, excellent thermal shock resistance, and desired Aggregates of particle size can be provided. Further, by using the zirconium-based composition of the present invention as a refractory material, the strength of the refractory can be improved, and mass production is easy, so that it is excellent in cost competitiveness and can be suitably used in this field. .

3 is a graph showing TMA measurement results of the powder obtained in Example 1. FIG. 6 is a graph showing the TMA measurement result of the powder obtained in Example 2. 6 is a graph showing TMA measurement results of the powder obtained in Example 3. 6 is a graph showing TMA measurement results of the powder obtained in Comparative Example 1. 6 is a graph showing a TMA measurement result of the powder obtained in Comparative Example 2. 10 is a graph showing TMA measurement results of the powder obtained in Comparative Example 3. 10 is a graph showing TMA measurement results of the powder obtained in Comparative Example 4. 10 is a graph showing TMA measurement results of the powder obtained in Comparative Example 5. 10 is a graph showing a TMA measurement result of the powder obtained in Comparative Example 6. 10 is a graph showing a TMA measurement result of the powder obtained in Comparative Example 7. 10 is a graph showing a TMA measurement result of the powder obtained in Comparative Example 8. 10 is a graph showing a TMA measurement result of the powder obtained in Comparative Example 9. It is a graph which shows the TMA measurement result of the zircon shown as a reference example.

The zirconium-based composition of the present invention contains 50 wt% or more of zirconium oxide, 25 to 40 wt% of silicon oxide, and 0.1 to 1 wt% of magnesium oxide based on zirconium oxide and silicon oxide, and contains 1.0 t. In the thermal behavior of the sintered body when it is molded at a pressure of / cm ² and fired at 1600 ° C., and the coefficient of thermal expansion during a heat cycle is increased from 30 ° C. to 1500 ° C. and then cooled to 30 ° C. The width is within 1.0%, the variation range of the thermal shrinkage rate is within 1.2%, and the thermal expansion coefficient and the thermal shrinkage ratio change due to the phase transition of zirconia occurring around 700-1100 ° C. are 0. .2% or less. That is, the change width of the thermal expansion coefficient due to the thermal expansion during the thermal cycle is within 1.0%, the change width of the thermal contraction ratio due to the heat shrinkage is within 1.2%, and the phase transition of zirconia occurring around 700 to 1100 ° C. If the change of the thermal expansion coefficient and thermal contraction rate accompanying this is 0.2% or less, it can be sufficiently put into practical use as a refractory.
Hereinafter, the zirconium-based composition of the present invention and the production method thereof will be described in detail.

Zirconium Composition (1) Composition of the Present Invention The main composition of the zirconium composition of the present invention is zirconium oxide, silicon oxide (silica), and magnesium oxide.
The content of zirconium oxide is 50 wt% or more, preferably 60 wt% or more, more preferably 63 to 72 wt%, and particularly preferably 65 to 70 wt%.
The content of silicon oxide is 25 to 40 wt%, preferably 28 to 37 wt%, more preferably 30 to 35 wt%. In addition, since silicon oxide may partially evaporate as fumed silica (SiO) during the electrofusion treatment, the content may be reduced.

  The content of magnesium oxide is 0.1 to 1 wt%, preferably 0.3 to 0.9 wt%, more preferably 0.5 to 0.8 wt% with respect to zirconium oxide and silicon oxide. When the content of magnesium oxide is less than 0.1 wt%, the effect of addition is not seen, and when it exceeds 1 wt%, excessive addition occurs, and the sintered body made of a zirconium-based composition exhibits thermal behavior close to that of zircon. Therefore, the thermal shock resistance and thermal cycle resistance are inferior. In addition, other alkaline earth metals such as calcium, barium, and strontium other than magnesium cannot obtain the same effect as the effect of the present invention as shown in a comparative example described later.

(2) Thermal behavior The zirconium-based composition of the present invention is characterized in that the thermal behavior (thermal expansion coefficient and thermal contraction rate) of the sintered body is close to that of zircon. For this reason, when the zirconium-based composition of the present invention is used as an aggregate, it can be used as an alternative to zircon, as well as the particle size can be adjusted, thereby improving the durability as a refractory. be able to.
The behavior of thermal expansion / shrinkage can be measured, for example, in the range of 100 to 1500 ° C. using a commercially available apparatus. Although the measurement may be performed at 1500 ° C. or higher, the temperature used as the refractory is usually 1500 ° C. or lower, and 1500 ° C. or lower is sufficient for evaluating the characteristics of the refractory.

The zirconium-based composition of the present invention exhibits a substantially constant thermal expansion behavior when fired to form a sintered body. In a graph showing the thermal expansion behavior, a linear heat similar to that of zircon is obtained. It becomes an expansion behavior. That is, the thermal expansion coefficient up to 1400 ° C. of the sintered body obtained by firing the zirconium-based composition of the present invention is 3.7 to 6.2 × 10 ⁻⁶ / K, and a more suitable range is 4.2 to 5. 7 × ¹⁰ -6 / K, a 4.7~5.2 × ^{10 -6} / K as further suitable range, much like the zircon thermal expansion coefficient of about 5.5 × ^{10 -6} / K Become.

The zirconium-based composition of the present invention is formed at a pressure of 1.0 t / cm ² and fired at 1600 ° C., as shown in Examples described later, from 30 ° C. (room temperature) to 1500 ° C. in the sintered body. As the thermal behavior during the thermal cycle of cooling to 30 ° C. (room temperature) after raising the temperature, the change width of the thermal expansion coefficient is within 1.0%, preferably within 0.9%, more preferably within 0.8%. More preferably, it is within 0.7%, and the change width of the heat shrinkage rate is within 1.2%, preferably within 1.0%, more preferably within 0.8%, and further preferably within 0.6%. The change in the coefficient of thermal expansion and contraction due to the phase transition of zirconia occurring at around 700 to 1100 ° C. at the time of temperature rise and temperature fall is 0.2% or less, preferably 0.15% or less, more preferably 0.1 % Or less. That is, it can be said that the sintered body of the zirconium-based composition of the present invention having such a thermal behavior is a low thermal expansion material comparable to zircon.

  In the present invention, details of the effect of adding magnesium oxide are not necessarily clear, but as shown in the examples described later, a small amount of magnesium oxide of 0.1 to 1 wt% with respect to zirconium oxide and silicon oxide is included in the composition. By adding, compared to the conventional one, ie, the one not added with magnesium oxide, the one added excessively with magnesium oxide, the one added with alkaline earth metal oxide other than magnesium oxide, etc. The volume due to the phase transition from monoclinic phase to tetragonal phase during the temperature rise and phase transition from the tetragonal phase to the monoclinic phase during the temperature fall can be suppressed while the thermal expansion change and thermal shrinkage change can be suppressed. Obviously, the change can be reduced.

(3) Particle size The particle size of the zirconium-based composition of the present invention can obtain a desired particle size in the range of μm order to several mm order, for example, in the range of 1 μm to 10 mm. Although the size of the ingot obtained after melting is derived from the size of the furnace body, ingots ranging from several centimeters to several tens of centimeters or more can be obtained by slow cooling. Usually, zircon sand has a particle size distribution of about 30 to 300 μm and an average particle size of about 100 μm or less, and a particle size larger than this cannot be obtained. For this reason, if the aggregate is about 300 μm or less, particularly 100 μm or less, the sized zircon sand can be used as it is. However, the aggregate having a particle size larger than that can be obtained from the zircon sand-derived aggregate. I can't. On the other hand, with the zirconium-based composition of the present invention, it becomes easy to obtain a powder having a particle size of 100 μm or more, which is a particle size range difficult to obtain from zircon. The particle size of the zirconium composition of the present invention is preferably such that 70% or more, preferably 80% or more, more preferably 90% or more of the particle size distribution is 100 μm or more. A specific particle size range that is easy to use as an aggregate is 100 μm or more, in the range 100 μm to 1000 μm, preferably 200 μm to 900 μm, more preferably 300 μm to 700 μm, and particularly preferably 400 μm to 600 μm. Of course, depending on the application, it may be 1000 μm or more, 2000 μm or more, 3000 μm or more.

  Moreover, what was controlled by the average particle diameter can also be used for the zirconium-based composition of this invention according to a use. For example, the sinterability and durability may be improved by combining fine particles and coarse particles. As the average particle size (D50), the same range as the above-mentioned particle size can be mentioned. That is, the specific average particle diameter is 100 μm to 1000 μm, preferably 200 μm to 900 μm, more preferably 300 μm to 700 μm, and particularly preferably 400 μm to 600 μm. Even in this case, the thickness may be 1000 μm or more, 2000 μm or more, 3000 μm or more depending on the application.

  Therefore, according to the zirconium-based composition of the present invention, the particle size can be arbitrarily adjusted, so that the aggregate can meet various particle size demands.

Method for producing zirconium-based composition of the present invention The method for producing a zirconium-based composition of the present invention was obtained by mixing a magnesium compound with a silicon compound and a zirconium compound or zirconium silicate, and the mixing step. It includes a melting step of melting the mixed powder at a melting point or higher, and a sizing step of cooling and sizing the melt obtained in the melting step.
(1) Raw Material The zirconium compound used in the zirconium-based composition of the present invention is not particularly limited, but is preferably a raw material containing zirconium oxide such as badelite, desiliconized zirconia and zirconium oxide. Further, as the zirconium oxide, oxides obtained from hydroxide, chloride, nitrate, carbonate, sulfate, acetate, bromide and the like can also be used.
The silicon compound is preferably a raw material containing silicon oxide. The silicon oxide may be an oxide obtained from hydroxide, nitride, carbide, chloride or the like, and raw materials can be appropriately selected in consideration of impurities and cost.
As zirconium silicate, zircon sand or a pulverized product of zircon sand can be used. Since zircon sand and pulverized products thereof can be obtained from the market at low cost, it is preferable to use them in the aggregate market.
These particle sizes are not particularly limited because they are melted, but those having a maximum particle size of 500 μm or less are desirable for suppressing unevenness during melting. Although not particularly limited, in the case of particles having a size of 1 μm or less, the particles are likely to be scattered due to a fusion arc impact, and should be avoided.
The magnesium compound is preferably a raw material containing magnesium oxide. Examples of magnesium oxide include oxides obtained from hydroxides, fluorides, chlorides, bromides, hydrides, borides, nitrides, and the like. Regarding the magnesium compound, the particle size when used as a raw material is not particularly limited because it melts, but is preferably 500 μm or less in order to suppress segregation due to the raw material.
The purity of the zirconium compound, silicon compound, zirconium silicate, and magnesium compound is not particularly limited, but is preferably 99% or more, and more preferably 99.5% or more.

When mixing a zirconium compound, a silicon compound, and a magnesium compound in the mixing step, the compounding ratio of the zirconium compound is, for example, 50% by weight or more, preferably 60% by weight or more, more preferably 63 to 72% by weight, particularly preferably as zirconium oxide. Is 65 to 70 wt%. The compounding ratio of the silicon compound is 25 to 40 wt%, preferably 28 to 37 wt%, more preferably 30 to 35 wt% as silicon oxide, and the compounding ratio of the magnesium compound is zirconium oxide and oxide as magnesium oxide. It is 0.1-1 wt% with respect to silicon, preferably 0.3-0.9 wt%, more preferably 0.5-0.8 wt%.
When using a material derived from zircon sand as a raw material, the composition of zirconium oxide and silicon oxide is generally determined, and the composition ratio depends on the production area, but zirconium oxide is 60 to 70 wt%, silicon oxide is Since it is about 30-40 wt%, it can be used as it is. That is, the raw material mixed powder of the zirconium compound of the present invention can be obtained by mixing zircon sand and magnesium oxide.
Since silicon oxide and magnesium oxide may partially evaporate during melting in the next melting step, the blending ratio may not be the composition ratio of the zirconium-based composition as it is.

(2) Granulation The raw material mixed powder can be granulated as necessary. For the production of the granulated material, general granulation methods of dry type and wet type can be used. For example, in the dry type, the mechanical alloying method in which compression and shearing force are applied, or the powders are fastened with each other in an air stream. There is a hybridization method for collision. In addition, in a wet process, a spray dryer method or an electroless plating method can be used alone or in combination. When producing a granulated material, a binder can also be added as needed. The binder is not particularly limited, but an organic binder is preferable to an inorganic binder from the viewpoint of impurities.

  Although the magnitude | size of a granulated material is not specifically limited, About 3-30 mm is preferable and about 10-20 mm is more preferable. The shape of the granulated product can be an arbitrary shape such as a cylindrical shape as well as a spherical shape.

(3) Melting The raw material mixed powder or granulated material is charged into a melting device in the melting step. Thereafter, the raw material mixed powder or granulated material is melted in the apparatus, and examples of the melting method include an arc method and a high-frequency thermal plasma method. Among them, a general electromelting method, that is, a melting method using an arc electric furnace can be preferably used.

In the case of a melting method using an arc electric furnace, the amount varies depending on the mixing ratio of the raw materials, but a predetermined amount of coke as a conductive material is required as necessary to promote initial energization of the raw material mixed powder or granulated material. Can be added. The atmosphere at the time of melting is not particularly limited, and may be an inert gas such as nitrogen, argon, or helium in addition to the air. For example, argon gas can be used to generate argon plasma and melt at a higher temperature. The argon plasma is a highly stable plasma that is also used for inductively coupled plasma emission analysis, and is extremely high in temperature, as reported to reach a temperature of 8000 ° C. or higher. For this reason, when argon plasma is generated using argon gas, the entire interior of the furnace can be maintained at a temperature higher than that obtained by an arc electric furnace alone, and the zirconium-based composition can be stably and efficiently produced. You can get an ingot.
Moreover, the pressure at the time of melting is not particularly limited, and any of normal pressure, pressurization, and depressurization may be used, but it can usually be performed under atmospheric pressure.
In the above granulation, when an organic binder is used, it is not an essential requirement, but the granulated product is preferably calcined at about 300 to 500 ° C. before the melting step. In the case of electromelting without calcination, scattering of the raw material powder occurs due to the impact when the organic binder burns instantaneously by application of arc plasma, and the composition deviation and yield of the resulting composition are reduced. May occur.

(4) Granulation In the granulation step, an ingot obtained by cooling after melting can be pulverized and classified to obtain a powder having a desired particle size. The ingot is not particularly limited, but it can be pulverized by a crusher such as a jaw crusher or a roll crusher, and is pulverized and classified to a powder of 20 mm or less, and if necessary, 1 to 10 mm or less. You can also.
In the sizing step, the powder obtained by the above method may be further finely pulverized according to the intended use. Although it does not specifically limit about fine pulverization, It can pulverize by processing for 5 to 30 minutes with grinders, such as a planetary mill, a ball mill, or a jet mill. The average particle size can be measured by a sieve particle size measurement for coarse particles of 25 μm or more, and can be analyzed by a laser diffraction scattering apparatus or the like for fine particles smaller than that.

Use of the Zirconium Composition of the Present Invention The zirconium composition of the present invention can be used as a refractory raw material. In particular, since the zirconium-based composition of the present invention can have a desired particle size, the aggregate can meet various particle size demands.
In addition, the refractory using the zirconium-based composition of the present invention as a raw material exhibits thermal behavior close to that of zircon compared to conventional refractories using aggregates derived from zircon sand, such as strength, heat resistance, thermal shock, etc. The characteristics required for the refractory can be improved. Such a refractory can be suitably used for applications such as a special metal melting crucible, for example.
The refractory using the zirconium-based composition of the present invention as a raw material can be produced by molding the zirconium-based composition of the present invention and firing the resulting molded body.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the examples. Moreover, in the material obtained in each Example and the comparative example, 1 to 2 weight% of hafnium oxide is contained as an inevitable impurity in zirconium oxide.

The TMA measurement conditions are as follows.
・ Device name: TD5000SA, manufactured by BRUKER ・ Temperature raising conditions: Room temperature to 1500 ° C. (5 ° C./min)
・ Cooling conditions: 1500 ° C to 50 ° C (5 ° C / min)
-Holding time at 1500 ° C: None (0 minutes)
Standard sample: Al ₂ O ₃
・ Atmosphere: Air
・ Weight: 10gf
-Pellet molding pressure: 1.0 t / cm ²

Example 1
As raw materials, 9.943 kg of zircon sand (Premium Zircon manufactured by ILUKA) was used as the zirconium compound and silicon compound, and 0.073 kg of magnesium oxide (Starmag U manufactured by Kamishima Chemical Co., Ltd.) was used as the magnesium compound. They were mixed for 30 minutes in a V-type mixer (MgO / ZrSiO ₄ mixing ratio: 0.7 wt%).
The obtained mixture was spread in an electromelting furnace and applied in the atmosphere at a voltage of 125 V and a current of 400 A for 1 hour to melt at or above the melting point of zircon. After the completion of melting, the mixture was allowed to stand for 30 hours and gradually cooled to obtain an ingot of the zirconium-based composition of the present invention.
The ingot was sized using a jaw crusher, a roll crusher, and a planetary mill, and a powder having an average particle diameter of 1 μm was prepared for evaluation of thermal behavior. When this powder was used for a fire resistance test, it was SK38.
Further, using 0.8 g of the above powder, a pellet was formed at a pressure of 1.0 t / cm ² and fired at 1600 ° C. for 3 hours to prepare a sintered body. This sintered body was measured by TMA, and the result is shown in FIG. According to this result, the change width of the thermal expansion coefficient is within 1.0%, the change width of the thermal shrinkage ratio is within 1.2%, and the change in the thermal expansion coefficient and the thermal shrinkage ratio in the vicinity of 700 ° C. to 1100 ° C. All were 0.2% or less.
For comparison, the dotted line shown in FIG. 1 is drawn corresponding to the position of the maximum expansion point of zircon shown in a reference example (FIG. 13) described later. The same applies to FIGS.

(Example 2)
The same operation as in Example 1 was conducted except that magnesium oxide was added so that the MgO / ZrSiO ₄ mixing ratio was 1.0 wt%.
Using the powder thus obtained, a sintered body was produced in the same manner as in Example 1. The TMA measurement result of this sintered body is shown in FIG. According to this result, the change width of the thermal expansion coefficient is within 1.0%, the change width of the thermal shrinkage ratio is within 1.2%, and the change in the thermal expansion coefficient and the thermal shrinkage ratio in the vicinity of 700 ° C. to 1100 ° C. All were 0.2% or less.

(Example 3)
The same operation as in Example 1 was carried out except that magnesium oxide was added so that the MgO / ZrSiO ₄ mixing ratio was 0.1 wt%.
Using the powder thus obtained, a sintered body was produced in the same manner as in Example 1. The TMA measurement result of this sintered body is shown in FIG. According to this result, the change width of the thermal expansion coefficient is within 1.0%, the change width of the thermal shrinkage ratio is within 1.2%, and the change in the thermal expansion coefficient and the thermal shrinkage ratio in the vicinity of 700 ° C. to 1100 ° C. All were 0.2% or less.

(Comparative Example 1)
The same procedure as in Example 1 was performed except that magnesium oxide was not added.
Using the powder thus obtained, a sintered body was produced in the same manner as in Example 1. The TMA measurement result of this sintered body is shown in FIG. According to this result, although the change width of the thermal expansion coefficient was within 1.0%, the change width of the thermal shrinkage ratio exceeded 1.2%, and the thermal expansion coefficient around 700 ° C. to 1100 ° C. and The change in heat shrinkage rate exceeded 0.2% in all cases.

(Comparative Example 2)
The same operation as in Example 1 was carried out except that magnesium oxide was added so that the MgO / ZrSiO ₄ mixing ratio was 1.3 wt%.
Using the powder thus obtained, a sintered body was produced in the same manner as in Example 1. The TMA measurement result of this sintered body is shown in FIG. According to this result, the change width of the thermal expansion coefficient is within 1.0%, the change width of the heat shrinkage ratio is within 1.2%, and the change in the heat shrinkage ratio between 700 ° C. and 1100 ° C. is 0.2%. %, The change in the coefficient of thermal expansion exceeded 0.2%.

(Comparative Example 3)
The same operation as in Example 1 was carried out except that magnesium oxide was added so that the MgO / ZrSiO ₄ mixing ratio was 1.5 wt%.
Using the powder thus obtained, a sintered body was produced in the same manner as in Example 1. The TMA measurement result of this sintered body is shown in FIG. According to this result, although the change width of the thermal expansion coefficient was within 1.0%, the change width of the thermal shrinkage ratio exceeded 1.2%, and the heat shrinkage near 700 ° C. to 1100 ° C. Although the change in the rate was 0.2% or less, the change in the coefficient of thermal expansion exceeded 0.2%.

(Comparative Example 4)
The same operation as in Example 1 was carried out except that magnesium oxide was added so that the mixing ratio of MgO / ZrSiO ₄ was 1.74 wt%.
Using the powder thus obtained, a sintered body was produced in the same manner as in Example 1. The TMA measurement result of this sintered body is shown in FIG. According to this result, the change width of the thermal expansion coefficient is within 1.0%, and the change of the thermal expansion coefficient and the thermal shrinkage ratio in the vicinity of 700 ° C. to 1100 ° C. were both 0.2% or less. The range of change in the shrinkage rate exceeded 1.2%.

(Comparative Example 5)
Instead of magnesium oxide, calcium oxide, CaO / ZrSiO ₄ mixing ratio, except that was added to a 0.94Wt%, was performed in the same manner as in Example 1.
Using the powder thus obtained, a sintered body was produced in the same manner as in Example 1. The TMA measurement result of this sintered body is shown in FIG. According to this result, although the change width of the thermal expansion coefficient was within 1.0%, the change width of the thermal shrinkage ratio exceeded 1.2%, and the thermal expansion around 700 ° C. to 1100 ° C. Although the change in rate was 0.2% or less, the change in heat shrinkage rate was more than 0.2%.

(Comparative Example 6)
Instead of magnesium oxide, barium oxide, BaO / ZrSiO ₄ mixing ratio, except that was added to a 1.5 wt%, was performed in the same manner as in Example 1.
Using the powder thus obtained, a sintered body was produced in the same manner as in Example 1. The TMA measurement result of this sintered body is shown in FIG. According to this result, the change width of the thermal expansion coefficient is within 1.0%, the change width of the heat shrinkage ratio is within 1.2%, and the change in the heat shrinkage ratio between 700 ° C. and 1100 ° C. is 0.2 %, The change in the coefficient of thermal expansion exceeded 0.2%.

(Comparative Example 7)
Instead of magnesium oxide, strontium oxide, SrO / ZrSiO ₄ mixing ratio, except that was added to a 0.7 wt%, was performed in the same manner as in Example 1.
Using the powder thus obtained, a sintered body was produced in the same manner as in Example 1. The TMA measurement result of this sintered body is shown in FIG. According to this result, although the change width of the thermal expansion coefficient was within 1.0%, the change width of the thermal shrinkage ratio exceeded 1.2%, and the heat shrinkage near 700 ° C. to 1100 ° C. Although the change in the rate was 0.2% or less, the change in the coefficient of thermal expansion exceeded 0.2%.

(Comparative Example 8)
Instead of magnesium oxide, aluminum _oxide, Al ₂ O 3 / ZrSiO ₄ mixing ratio, except that was added to a 0.7 wt%, was performed in the same manner as in Example 1.
Using the powder thus obtained, a sintered body was produced in the same manner as in Example 1. The TMA measurement result of this sintered body is shown in FIG. According to this result, although the change width of the thermal expansion coefficient was within 1.0% and the change width of the thermal shrinkage ratio was within 1.2%, the change in the thermal expansion coefficient and the thermal shrinkage ratio was both 0. It was over 2%.

(Comparative Example 9)
Instead of magnesium oxide, titanium _oxide, except that TiO 2 / ZrSiO ₄ mixing ratio was added to a 0.7 wt% was performed in the same manner as in Example 1.
Using the powder thus obtained, a sintered body was produced in the same manner as in Example 1. The TMA measurement result of this sintered body is shown in FIG. According to this result, although the change width of the thermal expansion coefficient was within 1.0% and the change width of the thermal shrinkage ratio was within 1.2%, the change in the thermal expansion coefficient and the thermal shrinkage ratio was both 0. It was over 2%.

(Reference example)
Using the zircon sand used as the raw material of Example 1, a sintered body was produced in the same manner as in Example 1. The TMA measurement result of this sintered body is shown in FIG.

Comparing the TMA measurement results of the example and the comparative example, the thermal behavior of the example is significantly different from the thermal behavior of the comparative example, and it is found that the thermal behavior of the zircon shown in the reference example is close. It was.
From the above, in the present invention, the effect of adding 0.1 to 1.0 wt% magnesium oxide was confirmed.

Claims (5)

50 wt% or more of zirconium oxide,
25-40 wt% silicon oxide;
A zirconium-based composition comprising 0.1 to 1 wt% magnesium oxide based on zirconium oxide and silicon oxide,
In the thermal behavior of the sintered body when molded at a pressure of 1.0 t / cm ² and fired at 1600 ° C., the thermal expansion during the thermal cycle of raising the temperature from 30 ° C. to 1500 ° C. and then cooling to 30 ° C. The rate of change in rate is within 1.0%, the rate of change in thermal shrinkage is within 1.2%, and the change in thermal expansion rate and thermal shrinkage due to the phase transition of zirconia is 0.2% or less. A zirconium-based composition characterized in that   2. The zirconium-based composition according to claim 1, wherein 70% or more on a volume basis in the particle size distribution is 0.1 mm or more. A method for producing a zirconium-based composition according to claim 1 or 2,
A mixing step of mixing a magnesium compound with a silicon compound and a zirconium compound or zirconium silicate;
A melting step of melting the mixed powder obtained in the mixing step above the melting point;
A sizing step for cooling and sizing the melt obtained in the melting step;
A process for producing a zirconium-based composition comprising:   A refractory containing the zirconium-based composition according to claim 1 as a raw material.   A method for producing a refractory, comprising: molding a powder containing the zirconium-based composition according to claim 1 or 2; and firing the molded article.

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