JP2014073932A - Thermal shock-resistant member, vessel for heat treatment and sliding nozzle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal shock-resistant member having excellent thermal shock resistance, a vessel for heat treatment, and a sliding nozzle.SOLUTION: Provided is a thermal shock-resistant member essentially consisting of magnesium oxide, comprising metal acid magnesium as an assistant component, and in which the average particle diameter of the crystal particles of the magnesium oxide in the surface is smaller than the average particle diameter of the crystal particles of the metal acid magnesium. By such constitution, owing to the presence of the crystal particles of the magnesium oxide having a relatively small particle diameter between the crystal particles of the metal acid magnesium, when heat stress is generated, it is dispersed in the grain boundary phase between the crystal particles of the magnesium oxide to increase a thermal shock resistance of the member.

Description

  The present invention relates to a thermal shock resistant member, a heat treatment container, and a sliding nozzle.

In heat treatment containers used for heat treating electronic components such as positive electrode materials (for example, LiMnO ₂ , LiCoO ₂ , LiNiO ₂ ), varistors, thermistors, piezoelectric elements and ceramic capacitors of lithium ion secondary batteries, For example, magnesium metalate such as magnesium aluminate is known as a material for a thermal shock-resistant member used for a sliding nozzle for controlling the flow rate of the molten metal when the molten metal flows out of the container.

  As magnesium oxide metal used as a thermal shock-resistant member, for example, Patent Document 1 proposes magnesium oxide metal having a maximum particle size of 3 mm or less and whose main components are magnesia and magnesia spinel.

Moreover, as a thermal shock-resistant member that can be used for a sliding nozzle, Patent Document 2 discloses a magnesium metalate comprising MgO particles having a particle size of d ₉₀ > 300 μm and magnesium aluminate having a particle size of d ₉₀ <100 μm. Has been proposed.

JP 2007-112670 A Special Table 2010-501462

  However, the magnesium metalate proposed in Patent Document 1 and Patent Document 2 has room for improvement in terms of thermal shock resistance.

  In view of such problems, the present invention provides a thermal shock-resistant member having improved thermal shock resistance, a heat treatment container, and a sliding nozzle.

  The thermal shock-resistant member of the present invention comprises magnesium oxide as a main component and magnesium oxide as a subcomponent, and the average particle size of the magnesium oxide crystal particles on the surface is the average particle size of the magnesium oxide crystal particles. It is characterized by being smaller than.

  The heat treatment container of the present invention is characterized in that the above-mentioned thermal shock resistant member is used as a support for the object to be fired.

  Moreover, the sliding nozzle of the present invention is characterized by using the above thermal shock resistant member.

According to the thermal shock-resistant member of the present invention, magnesium oxide is the main component, magnesium metalate is a minor component, and the average particle size of magnesium oxide crystal particles on the surface is the average particle size of magnesium metal crystal particles. The grain boundary phase between the magnesium oxide crystal particles when thermal stress occurs due to the presence of magnesium oxide crystal particles having a relatively small particle size between the crystal particles of magnesium metalate. The thermal shock resistance can be improved.

  In addition, according to the heat treatment container of the present invention, since the thermal shock resistant member of the present invention is used as a support for an object to be fired, it can be used for a long time.

  Moreover, according to the sliding nozzle of this invention, since it uses the thermal shock-resistant member of this invention, it can be used over a long period of time.

An example of the heat treatment container of the present embodiment is shown, (a) is a perspective view, and (b) is a cross-sectional view taken along line A-A ′. It is sectional drawing which shows typically the sliding nozzle of this embodiment.

  Hereinafter, the thermal shock resistant member of this embodiment will be described in detail.

  The thermal shock resistant member of the present embodiment has magnesium oxide as a main component and magnesium oxide metal as a subcomponent, and the average particle diameter of magnesium oxide crystal particles on the surface is larger than the average particle diameter of magnesium metal oxide crystal particles. Is also small. With such a configuration, when thermal stress occurs due to the presence of magnesium oxide crystal particles having a relatively small particle size between the magnesium metalate crystal particles, the particles between the magnesium oxide crystal particles Since thermal stress is dispersed in the boundary phase, the thermal shock resistance is enhanced.

  Furthermore, the magnesium oxide crystal particles have an average particle size smaller than the average particle size of the magnesium oxide crystal particles, in other words, there are magnesium oxide crystal particles larger than the average particle size of the magnesium oxide crystal particles. As a result, voids may occur between the magnesium metalate crystal particles and the magnesium oxide crystal particles along the magnesium metalate crystal particles. When thermal stress is generated, the voids are buffered. Since it functions as a part, the thermal shock resistance tends to increase.

  The thermal shock resistant member of the present embodiment contains more than 50% by mass of the main component magnesium oxide, and particularly when 60% by mass or more is contained, the heat resistance and the corrosion resistance to the alkali component are increased. Therefore, it is preferable. In addition, the main component and subcomponent in this embodiment mean the component with the largest content after the component with the largest content and the component with the largest content among the components contained in the thermal shock resistant member.

  The composition of the component contained in the thermal shock resistant member can be identified using an X-ray diffraction method. The amount of each element contained in the thermal shock resistant member can be determined by fluorescent X-ray analysis or ICP (Inductively Coupled Plasma) emission spectroscopy. For example, the content of magnesium oxide as the main component is obtained by calculating the total content of magnesium in the thermal shock-resistant member, converting it to magnesium oxide, and the amount of magnesium oxide constituting magnesium metalate (calculation method will be described later). ) Is the content of magnesium oxide, the main component.

  In addition, the component amount of magnesium oxide composing the metal acid magnesium can be calculated as described below. First, the content of a metal other than magnesium (excluding inevitable impurities) is obtained, and the value converted from this content into an oxide is regarded as the component amount of a metal oxide other than magnesium constituting the metal acid magnesium. Then, from the composition of the magnesium metalate identified by the above method, the ratio of the oxide component of the metal other than magnesium and the magnesium oxide component is obtained, and the amount of the magnesium oxide component constituting the magnesium metalate is calculated. Good.

Here, as magnesium metalate, for example, magnesium aluminate, magnesium titanate, magnesium tantalate, or magnesium tungstate can be used. In addition, the composition formula of magnesium aluminate is expressed as MgAl ₂ O ₄ , and the molar ratio of MgO and Al ₂ O ₃ is preferably a constant ratio of 1: 1, but MgO and Al ₂ O ₃ and For example, the molar ratio is in the range of 1: 0.8 to 1: 1.2. Further, the composition formula of magnesium titanate is expressed as MgTiO ₃ , and the molar ratio of MgO and TiO ₂ is preferably a constant ratio of 1: 1, but the molar ratio of MgO and TiO ₂ is, for example, 1: 0.8 ~
If it is in the range of 1: 1.2, there is no problem. Magnesium tantalate has the composition formula M
It is expressed as g ₄ Ta ₂ O ₉ and the molar ratio of MgO to Ta ₂ O ₅ is preferably a constant ratio of 4: 1, but the molar ratio of MgO to Ta ₂ O ₅ is, for example, 4 : Any value within the range of 0.8 to 4: 1.2 is acceptable. In addition, the magnesium tungstate is represented by the composition formula MgWO ₃ , and the molar ratio of MgO and WO ₃ is preferably a constant ratio of 1: 1, but the molar ratio of MgO and WO ₃ is, for example, There is no problem as long as it is in the range of 1: 0.8 to 1: 1.2. The magnesium metalate, which is a subcomponent of the thermal shock resistant member, may be appropriately selected from magnesium aluminate, magnesium titanate, magnesium tantalate or magnesium tungstate depending on the application, but in terms of cost reduction, aluminate It is preferred to select magnesium.

Moreover, the average particle diameter of each crystal particle of magnesium oxide and magnesium metal oxide on the surface of the thermal shock resistant member can be obtained by the following procedure. A cylindrical sample is prepared by embedding a part of the thermal shock-resistant member in a cold embedding resin such as polyester resin so that the surface becomes an observation surface, and the surface of this sample is, for example, a polishing machine (Ecomet 3 , Polished using a Bühler (manufactured)) to obtain an observation surface. Then, using a scanning electron microscope, the reflected electron composition image obtained by photographing the observation surface of the thermal shock-resistant member at a magnification of, for example, 20 times, and an electron beam is irradiated onto the observation surface using an X-ray microanalyzer. By comparing image data representing the abundance ratio of elements analyzed by detecting generated characteristic X-rays, it is possible to specify the components of the crystal particles constituting the observation surface. For example, in a thermal shock-resistant member containing magnesium oxide as the main component and magnesium metalate as the accessory component, the crystal particles in which the presence of magnesium is recognized more than other components are magnesium oxide crystal particles, and the metal acid The crystal particles in which the presence of magnesium constituting magnesium and a metal other than magnesium are observed more than the other components are crystal particles of magnesium metalate. The average particle size of each crystal particle of magnesium oxide and magnesium metal oxide is, for example, image analysis software “IMAGE-PRO PLUS” (registered trademark, MEDIA).
Using CYBERNETICS, the number of samples is 30 and the equivalent circle diameter is calculated, and the average value is obtained.

  Further, the thermal shock resistant member of the present embodiment is a ratio (p75 / p25) of the pore volume (p75) of 75 volume% to the pore diameter (p25) of 25 volume% in the cumulative distribution curve of pore diameter (hereinafter referred to as “p75 / p25”). The ratio (p75 / p25) is preferably 1.1 or more and 1.5 or less.

  When the ratio (p75 / p25) is 1.1 or more and 1.5 or less, the variation in pore diameter is reduced, so both the thermal shock resistance and mechanical properties can be improved. It is possible to make it difficult for cracks to occur in the adhesive member.

The pore diameters (p25) and (p75) of the thermal shock resistant member are obtained by, for example, obtaining the pore diameter of the thermal shock resistant member by the following formula (1), and accumulating 25 volume% and 75 volume% in the cumulative distribution curve. Can be obtained as pore diameters (p25) and (p75), respectively. The pore size cumulative distribution curve is a curve showing the cumulative distribution of pore diameters, where the horizontal axis in the two-dimensional graph is the pore diameter and the vertical axis is the percentage of the cumulative pore volume of the pore diameter. It shows the distribution range of.

  What is necessary is just to obtain | require about the pore diameter (p25) and (p75) of the pore of this thermal shock-resistant member based on the mercury intrusion method. Specifically, first, a sample is cut out from the thermal shock resistant member so that the mass is 2 g or more and 3 g or less. Next, using a mercury intrusion porosimeter, mercury is injected into the pores of the sample, and the pressure applied to the mercury and the volume of mercury that has entered the pores are measured.

The volume of mercury is equal to the volume of pores, and the following formula (1) (Washburn's relational expression) is established for the pressure applied to mercury and the pore diameter.
p = -4σ cos θ / P (1)
Where p: pore diameter (m)
P: Pressure applied to mercury (Pa)
σ: Surface tension of mercury (0.485N / m)
θ: Contact angle between mercury and pore surface (130 °)
From the equation (1), each pore diameter p for each pressure P is obtained, and distribution of each pore diameter p and cumulative pore volume can be derived. And what is necessary is just to obtain | require each pore diameter (p25) and (p75) in which the percentage of a cumulative pore volume corresponds to 25 volume% and 75 volume%.

  In addition, the thermal shock resistant member of this embodiment preferably has a porosity of 15% by volume to 30% by volume. When the porosity is within this range, the thermal shock resistance and mechanical strength can be kept high. The porosity of the thermal shock resistant member can be determined according to the Archimedes method.

The thermal shock-resistant member of the present embodiment is suitable when the average particle diameter of the magnesium oxide crystal particles is 52 μm or more and 300 μm or less because, for example, both corrosion resistance and thermal shock resistance against alkali components can be maintained high. is there. Further, it is preferable that the average particle diameter of the magnesium oxide crystal particles is 52 μm or more and 204 μm or less because the thermal shock resistance can be maintained higher.

Furthermore, it is preferable that the thermal shock-resistant member of the present embodiment has an average particle diameter of magnesium metal oxide crystal particles of 1 mm or less (excluding 0 mm). When the average particle size of the magnesium oxide crystal particles is 52 μm or more and 300 μm or less, the spalling resistance of the metal acid magnesium can be improved by setting the average particle size of the metal particle magnesium oxide within the above range. it can. In addition, the spalling resistance in the present embodiment refers to a characteristic that when a thermal shock resistant member is subjected to a thermal shock, a crack is generated and a magnesium oxide or magnesium metal oxide crystal is hardly peeled off. The thermal shock-resistant member having such a structure is, for example, a heat treatment container for heat-treating an object to be fired containing an alkaline component such as a positive electrode material, a varistor, a thermistor, a piezoelectric element and a ceramic capacitor of a lithium ion secondary battery. It can be suitably used as a member. The average particle size of the magnesium oxide crystal particles is 52 μm or more and 300
In the case of μm or less, it is preferable that the average particle size of the magnesium metalate crystal particles is 600 μm or less because the spalling resistance can be further improved.

  Hereinafter, the heat treatment container of the present embodiment will be described with reference to the drawings.

  1A and 1B show an example of a heat treatment container according to the present embodiment. FIG. 1A is a perspective view, and FIG. 1B is a cross-sectional view taken along line A-A ′.

The heat treatment container of the example shown in FIG. 1 supports the thermal shock-resistant member of this embodiment described above to support an object to be fired (for example, a positive electrode material of a lithium ion secondary battery, a varistor, a thermistor, a piezoelectric element, and a ceramic capacitor). A heat treatment container 10 provided as a body, which includes a support 1 made of a thermal shock-resistant member and a frame 2 placed on the support 1. For example, the frame 2 is preferably made of a ceramic porous body mainly composed of alumina, mullite, or cordierite. In particular, it is more preferable from the viewpoint of heat resistance that the frame body 2 is made of a ceramic porous body containing cordierite as a main component, a content of 60 mass% or more, and mullite as a subcomponent. Note that the thermal shock-resistant member of this embodiment can be used as the frame 2.

  The heat treatment container 10 of the present embodiment uses the thermal shock resistant member of the present embodiment as a support for the object to be fired. Can do. Furthermore, even if an alkali component is contained in the object to be fired, the support 1 containing magnesium oxide that is not easily eroded by the alkali component is hardly eroded by the alkali component.

  In addition to the heat treatment container 10 described above, the thermal shock resistant member of the present embodiment described above can also be suitably used as a member that constitutes a rotary retort furnace or a rotary heat treatment furnace.

The thermal shock resistant member of the present embodiment can maintain both high corrosion resistance and thermal shock resistance against alkali components when the average particle diameter of the magnesium oxide crystal particles is 1 mm to 1.5 mm. Even if it is exposed to a high temperature environment of 1500 ° C. or higher, it can be used for a long time. Furthermore, the thermal shock-resistant member of the present embodiment has an average particle diameter of magnesium metal crystal particles of 2.5 mm or less (however, 0 mm) when the average particle diameter of magnesium oxide crystal particles is 1 mm or more and 1.5 mm or less. In this case, the spalling resistance of the magnesium metalate can be improved. The thermal shock-resistant member having such a configuration can be suitably used as a member for a sliding nozzle that is exposed to a molten metal containing an alkali component and used in a high temperature environment of 1500 ° C. or higher. Further, when the average particle diameter of the magnesium oxide crystal particles is 1 mm or more and 1.5 mm or less, the average particle diameter of the magnesium metalate crystal particles is preferably 2 mm or less because the spalling resistance can be further improved. is there.

  Hereinafter, the sliding nozzle of this embodiment will be described with reference to the drawings.

  FIG. 2 is a cross-sectional view schematically showing the sliding nozzle of the present embodiment.

  The sliding nozzle 20 of the example shown in FIG. 2 is for controlling the flow rate of the molten metal to be supplied from the ladle 3 to a tundish (not shown) that is a receiving tray for holding the molten metal. . The sliding nozzle 20 is inserted into the opening 3a at the bottom of the ladle 3 and fixed to the inner hole 4a of the tuyere brick 4, and the sliding nozzle whose inlet side is connected to the lower end of the upper nozzle 5. A plate 6 and a lower nozzle 7 having an upper end connected to the outlet side of the sliding nozzle plate 6 are provided.

  The sliding nozzle plate 6 includes an upper plate 6a attached to the bottom lower surface of the ladle 3 via a metal frame (not shown), and a lower plate 6b slidably contacting the upper plate 6a. 7 moves together with the lower plate 6b when the lower plate 6b moves. The sliding nozzle 20 controls the flow rate of the molten metal by communicating or blocking the outflow holes 6c and 6d by sliding the lower plate 6b in the horizontal direction. Sometimes, when the lower nozzle 7 is in the position shown in FIG. 2, hot molten metal is supplied from the ladle 3 to the tundish (not shown) through the upper nozzle 5, the sliding nozzle plate 6 and the lower nozzle 7 in sequence.

Here, it is preferable that the upper nozzle 5, the sliding nozzle plate 6 and the lower nozzle 7 constituting the sliding nozzle 20 are made of the thermal shock resistant member of this embodiment, but the upper nozzle 5, the sliding nozzle plate 6 and the lower nozzle At least one of 7 may be made of the thermal shock resistant member of the present embodiment. Since the thermal shock-resistant member of this embodiment is not easily broken by thermal stress even when repeatedly exposed to a high-temperature molten metal, the sliding nozzle 20 using the thermal shock-resistant member can be used for a long period of time.

  Next, a method for manufacturing the thermal shock resistant member and the heat treatment container of this embodiment will be described.

First, magnesium oxide powder and at least one of aluminum oxide, titanium oxide, tantalum oxide and tungsten oxide so that the main component and subcomponent constituting the thermal shock resistant member are magnesium oxide and magnesium metalate, respectively. For example, 65% by weight to 80% by weight and 20% by weight to 35% by weight. Here, the average grain size of the crystal grains of magnesium oxide in the surface to obtain a small heat shock resistance member than the average grain size of crystal grains of magnesium metal acid, average particle diameter (D ₅₀₎ having a larger particle size distribution The average particle size of the magnesium oxide powder (D ₅₀ ) is smaller than the average particle size (D ₅₀ ) of the oxide powder selected from at least one of aluminum oxide, titanium oxide, tantalum oxide, and tungsten oxide. That's fine.

Here, in order to obtain a thermal shock resistant member in which the average particle diameter of the magnesium oxide crystal particles is 52 μm or more and 300 μm or less, the average particle diameter (D ₅₀ ) of aluminum oxide, titanium oxide, tantalum oxide and tungsten oxide powder is 52 μm. The thickness may be 300 μm or less.

In addition, in order to obtain a thermal shock resistant member in which the average particle diameter of magnesium metalate crystal particles is 1 mm or less, the average particle diameter (D ₅₀ ) of the magnesium metalate powder may be 1 mm or less.

In addition, in order to obtain a thermal shock resistant member having an average particle diameter of magnesium oxide crystal particles of 1 mm or more and 1.5 mm or less, the average particle diameter (D ₅₀ ) of aluminum oxide, titanium oxide, tantalum oxide and tungsten oxide powder is 1 mm. It may be set to 1.5 mm or less.

In addition, in order to obtain a thermal shock resistant member in which the average particle diameter of magnesium metalate crystal particles is 1 mm or less, the average particle diameter (D ₅₀ ) of the magnesium metalate powder may be 1 mm or less.

  Then, a plasticizer, a slip agent, a dispersant, an organic binder, water, and the like are added to the prepared powder, and a kneaded product is prepared using a universal stirrer, a rotary mill, a V-type stirrer, or the like. And this kneaded material is knead | mixed using a three roll mill, a kneader, etc., and the plasticized clay is obtained.

  Next, this clay is put into an extrusion molding machine equipped with a mold and pressed to obtain a green sheet. The green sheet is dried and then cut to obtain a molded body. In addition, when the sliding nozzle plate 6 is obtained, the green sheet may be perforated to form a molded body.

  The obtained molded body is placed in a firing furnace such as an electric furnace or a gas furnace. In order to obtain a thermal shock-resistant member whose subcomponent is magnesium aluminate, the temperature may be set to 1620 ° C. or higher and 1680 ° C. or lower in the air atmosphere and held for 5 to 15 hours.

  Here, in order to obtain a thermal shock-resistant member having a porosity of 15% by volume or more and 30% by volume or less, the temperature is set to, for example, 1625 ° C. or more and 1675 ° C. or less, and held for 5 to 15 hours, whereby the above-described heat resistance An impact member can be obtained.

In order to obtain a thermal shock-resistant member whose subcomponent is magnesium titanate, the temperature may be kept at 1250 ° C. or higher and 1380 ° C. or lower in the air atmosphere for 5 to 15 hours.

  In order to obtain a thermal shock resistant member in which the subcomponent is magnesium tantalate, the temperature is set to 1400 ° C. or higher and 1600 ° C. or lower in the air atmosphere and held for 5 to 15 hours.

  In order to obtain a thermal shock-resistant member whose subcomponent is magnesium tungstate, the temperature may be kept at 975 ° C. or higher and 1050 ° C. or lower in the air atmosphere for 5 to 15 hours.

In addition, in order to obtain a thermal shock resistant member having a pore diameter ratio (p75 / p25) of 1.1 or more and 1.5 or less, the cumulative particle size of the prepared powder is 25% by volume (d ₂₅ ) in the cumulative distribution curve. The ratio (d ₇₅ / d ₂₅ ) of the particle size (d ₇₅ ) of cumulative 75 volume% may be 1.05 or more and 1.45 or less.

  By shaping the obtained thermal shock-resistant member with abrasive paper or a polishing cloth, the support 1 made of the thermal shock-resistant member of this embodiment can be obtained.

  Then, by placing the frame 2 mainly composed of alumina, mullite or cordierite produced by a known manufacturing method on the support 1, the heat treatment container 10 of the present embodiment can be obtained.

  Next, a method for manufacturing the sliding nozzle 20 of this embodiment will be described.

First, the average particle diameter (D ₅₀ ) of the powder is changed, the average particle diameter of the magnesium oxide crystal particles of the thermal shock resistant member is 1 mm to 1.5 mm, and the average particle diameter of the magnesium metalate crystal particles is 2.5 mm. A sliding plate 6 is produced in the same manner as the support 1 except that the following is achieved.

Then, the average particle diameter (D ₅₀ ) of the powder is changed, the average particle diameter of the magnesium oxide crystal particles of the thermal shock-resistant member is 1 mm to 1.5 mm, and the average particle diameter of the magnesium metalate crystal particles is 2.5 mm. To the powder prepared by the same manufacturing method as the support 1 except that the following:
Using a barrel mill, rotating mill, vibration mill, bead mill, or attritor, etc., wet-mixed with 2-propanol and pulverized to obtain a slurry. The obtained slurry is dried using a spray drying method to obtain granules. Next, after the obtained granule is filled in a mold, it is pressed at a pressure of 60 MPa or more and 100 MPa or less by a pressure molding method to obtain a cylindrical molded body. The obtained molded body is placed in a firing furnace such as an electric furnace or a gas furnace. When the accessory component is magnesium aluminate, magnesium titanate, magnesium tantalate, or magnesium tungstate, the temperature is 1550 ° C to 1620 ° C, 1250 ° C to 1380 ° C, 1400 ° C to 1600 ° C, respectively. The precursors of the upper nozzle 5 and the lower nozzle 7 can be obtained by baking at 5 ° C. or lower and 975 ° C. or higher and 1050 ° C. or lower and 1050 ° C. or lower.

  And the upper nozzle 5 and the lower nozzle 7 can be obtained by shaping the precursor of the obtained upper nozzle 5 and the lower nozzle 7 by a well-known method.

  Then, the sliding nozzle 20 of the present embodiment can be obtained by combining the upper nozzle 5, the sliding plate 6 and the lower nozzle 7 as shown in FIG.

  Examples of the present invention will be specifically described below, but the present invention is not limited to these examples.

  First, magnesium oxide and magnesium aluminate, which are components constituting the thermal shock-resistant member, were 67 mass% and 33 mass%, respectively, and the average particle diameters of the crystal grains of magnesium oxide and magnesium aluminate of each sample are shown in Table 1. Each powder of magnesium oxide and aluminum oxide was prepared so as to have the value shown in FIG.

  And the plasticizer, the slip agent, the dispersing agent, the organic binder, and water were added to the prepared powder, and the kneaded material was produced using the universal stirrer. And this kneaded material was kneaded by a three-roll mill to obtain a plasticized clay.

Next, clay was put into an extruder and pressed to obtain a green sheet having a thickness of 0.65 mm. The green sheet was dried and then cut to obtain a square substrate-like molded body having a side of 330 mm.

  Next, the clay was put into an extruder and pressurized to obtain a green sheet. The green sheet was dried and then cut to obtain prismatic shaped bodies having widths, thicknesses and lengths of 4.4 mm, 3.3 mm, and 40 mm, respectively, which became test pieces specified in JIS R 1601-2008.

  Then, after placing the substrate-like and columnar shaped bodies in an electric furnace, a thermal shock resistant member was obtained by setting the maximum temperature and holding time in air atmosphere to 1560 ° C. and 10 hours, respectively. These thermal shock-resistant members are shaped with abrasive paper, and the substrate-shaped and prismatic sample Nos. 1 to 10 were obtained, respectively.

  Furthermore, prismatic sample No. The thermal shock damage resistance R of 1 to 10, the longitudinal elastic modulus (E) and Poisson's ratio (ν) of each sample according to the ultrasonic pulse method described in JIS R 1602-1995, and 3 points The bending strength (S) was calculated according to JIS R 1601-2008, and the obtained value was calculated by substituting into the following formula (2).

R = E / (S ² × (1−ν)) (2)
Note that the thermal shock damage resistance R is a parameter indicating the thermal shock performance of a sample by paying attention to how much cracks generated when a thermal shock is applied. This indicates that cracks due to thermal shock are unlikely to develop and that the thermal shock resistance is excellent.

  Furthermore, the thermal shock resistance of the thermal shock resistant member after being exposed to a strongly alkaline gas was evaluated by the following method.

First, 5 g of a powder obtained by mixing lithium oxide and cobalt oxide powder, which is a raw material of lithium cobaltate, which is one of the components constituting the positive electrode material of a lithium ion secondary battery, and a substrate-like thermal shock-resistant member are fired in a furnace Placed in. In addition, this powder is a powder for generating gas with strong alkalinity, and was disposed at a position away from the thermal shock resistant member. This cycle is defined as a temperature rising and cooling process in which the maximum temperature and holding time are held as 1000 ° C. and 3 hours, respectively, and then cooled to 420 ° C. in a firing furnace and then air-cooled outside the firing furnace. Was repeated 30 cycles.

  Then, after 30 cycles, the main surface of the thermal shock-resistant member was observed using an optical microscope at a magnification of 50 times, and the sample in which cracks were observed on the main surface was acceptable, and the sample that was not observed was superior. As shown in Table 1.

  As can be seen from the results shown in Table 1, Sample No. 2 to 9 are composed of magnesium oxide as a main component, magnesium aluminate as a subcomponent, and a thermal shock-resistant member in which the average particle size of magnesium oxide crystal particles on the surface is smaller than the average particle size of magnesium aluminate crystal particles Therefore, sample no. It can be said that the thermal shock damage resistance R is larger than those of 1 and 10, cracks due to thermal shock hardly propagate, and the entire thermal shock resistant member is difficult to crack.

In particular, sample no. 3-8, the average particle size of magnesium oxide crystal particles that are not easily eroded by alkali components is 52 μm or more and 300 μm or less. It can be said that it is a thermal shock resistant member having excellent impact properties.

  First, magnesium oxide and magnesium aluminate, which are components constituting the thermal shock-resistant member, are 67% by mass and 33% by mass, respectively, and the average particle diameters of magnesium oxide and magnesium aluminate of each sample are the values shown in Table 2. Thus, each powder of magnesium oxide and aluminum oxide was weighed and prepared.

  Then, a substrate-like molded body was obtained by the same method as shown in Example 1.

  And after arrange | positioning this molded object in an electric furnace, the thermal shock member was obtained by making the maximum temperature and holding time into 1560 degreeC and 10 hours, respectively in air | atmosphere. These thermal shock resistant members are shaped with abrasive paper, and sample No. 11-14 were obtained.

  Sample No. For the thermal shock resistance of 11 to 14, the temperature rise and cooling process shown in Example 1 was repeated using the above thermal shock resistant member, and the number of cycles in which cracks were first observed on the main surface of the thermal shock resistant member was shown. It was shown in 2.

  As can be seen from the results shown in Table 2, the sample No. 1 in which the average particle size of the magnesium aluminate crystal particles is 1 mm or less is used. In Nos. 11 to 13, the number of cycles in which cracks were observed was 42 cycles or more. Compared to 14, it can be said that cracks are less likely to occur even when thermal shock is repeatedly applied. Sample No. Nos. 11 to 13 are considered to have high spalling resistance because the crystal grains of magnesium oxide and magnesium aluminate are not easily peeled off because cracks are hardly generated even when repeated thermal shocks are applied.

  First, magnesium oxide and magnesium aluminate, which are components constituting the thermal shock-resistant member, are 67% by mass and 33% by mass, respectively, and the ratio (p75 / p25) of the pore diameters (p25) and (p75) of each sample is shown. Each powder of magnesium oxide and aluminum oxide was weighed and prepared so that the value shown in 3 was obtained. The powder particles were adjusted so that the average particle diameters of magnesium oxide and magnesium aluminate in each sample were 148 μm and 420 μm.

  Then, in the same manner as in Example 2, the substrate-like sample No. 1 that becomes the support 1 shown in FIG. 15-20 were produced.

  Then, 20 g of the powder obtained by mixing the lithium oxide and cobalt oxide powders, which are components of the lithium cobalt oxide raw material powder, was added to each of the substrate-like sample Nos. Place on the upper surface of 15-20, set the maximum temperature and holding time in the continuous firing furnace (roller hearth kiln) to 1000 ° C for 3 hours respectively, then cool to room temperature, then put the placed powder This cycle was repeated with the process of removing as one cycle. Table 3 shows the number of cycles in which cracks were first observed visually in each sample.

  As can be seen from the results shown in Table 3, the sample No. 1 in which the ratio (p75 / p25) of the pore diameters (p25) and (p75) is 1.1 or more and 1.5 or less. Nos. 15 to 19 are sample Nos. In which the variation in pores is suppressed, and the ratio (p75 / p25) of the pore diameters (p25) and (p75) is outside the range of 1.1 to 1.5. Compared to 1620, it can be said that cracks are less likely to occur even when used repeatedly for heat treatment.

  First, magnesium oxide and magnesium aluminate, which are components constituting the thermal shock-resistant member, are 67% by mass and 33% by mass, respectively, and the average particle diameters of magnesium oxide and magnesium aluminate of each sample are the values shown in Table 4. Thus, each powder of magnesium oxide and aluminum oxide was weighed and prepared.

  Then, in the same manner as in Example 2, the substrate-like sample No. 1 that becomes the support 1 shown in FIG. 21-29 were produced.

  Next, the thermal shock resistance after being exposed to a high-temperature molten metal was evaluated by the following method.

First, sample no. Width, thickness and length from 21 to 29 are 40mm, 40mm and 180mm respectively
A test piece was cut out. Then, after immersing these test pieces in molten pig iron at 1600 ° C. for 3 minutes, and taking them out and cooling with water as one cycle, the presence or absence of cracks was visually observed every cycle. Table 4 shows the number of cycles in which cracks were first observed. In Table 4, “> 5” indicates that no cracks were observed after 5 cycles.

  As can be seen from the results shown in Table 4, sample No. 21 to 28 are composed mainly of magnesium oxide and magnesium aluminate as a subsidiary component, and the average particle size of magnesium oxide crystal particles on the surface is smaller than the average particle size of magnesium aluminate crystal particles, so that Even if a thermal shock is applied, cracking hardly occurs and the thermal shock resistance is high.

In particular, Sample N in which the average particle diameter of magnesium oxide crystal particles is 1 mm or more and 1.5 mm or less.
o. It can be said that 22 to 27 are less susceptible to cracking even when repeated thermal shocks are applied.

  First, magnesium oxide and magnesium aluminate, which are components constituting the thermal shock-resistant member, were made 67 mass% and 33 mass%, respectively, and the average particle diameters of magnesium oxide and magnesium aluminate of each sample were as shown in Table 5. Thus, each powder of magnesium oxide and aluminum oxide was weighed and prepared.

  Then, in the same manner as in Example 2, the substrate-like sample No. 1 that becomes the support 1 shown in FIG. 30-33 were produced.

  Sample No. 30 to 33 show the number of cycles in which the process shown in Example 4 was repeated and cracks were first observed on the main surface of the thermal shock resistant member.

As can be seen from the results shown in Table 5, the sample No. 1 in which the average particle diameter of the magnesium aluminate crystal particles is 2.5 mm or less is used. Samples Nos. 30 to 32 had a number of cycles in which cracks were observed of 10 or more. Compared to 33, cracks are less likely to occur even when repeated thermal shocks are applied. Sample No. Nos. 30 to 32 are considered to have high spalling resistance because the crystal particles of magnesium oxide and magnesium metal oxide are not easily peeled off because cracks are hardly generated even when repeated thermal shocks are applied.

1: Support body 2: Frame body 3: Ladle 4: Tail brick 5: Upper nozzle 6: Sliding nozzle plate 7: Lower nozzle
10: Container for heat treatment
20: Sliding nozzle

Claims (8)

  Heat resistance characterized by comprising magnesium oxide as a main component and magnesium metalate as a subcomponent, wherein the average particle size of the magnesium oxide crystal particles on the surface is smaller than the average particle size of the magnesium metalate crystal particles Impact member.   The ratio (P75 / P25) of the pore volume (P75) of the cumulative 75 volume% to the pore diameter (P25) of the cumulative 25 volume% in the cumulative distribution curve of the pore diameter is 1.1 or more and 1.5 or less. The thermal shock resistant member according to claim 1.   The thermal shock-resistant member according to claim 1 or 2, wherein an average particle diameter of the magnesium oxide crystal particles is 52 µm or more and 300 µm or less.   The thermal shock-resistant member according to claim 3, wherein an average particle diameter of the magnesium metal crystal crystal particles is 1 mm or less.   A heat treatment container comprising the thermal shock resistant member according to any one of claims 1 to 4 as a support for an object to be fired.   The thermal shock-resistant member according to claim 1 or 2, wherein an average particle diameter of the magnesium oxide crystal particles is 1 mm or more and 1.5 mm or less.   The thermal shock-resistant member according to claim 6, wherein an average particle diameter of the magnesium metalate crystal particles is 2.5 mm or less.   A sliding nozzle comprising the thermal shock resistant member according to claim 6 or 7.

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