KR910009890B1 - Novel solid solution heat-resistant sintered body and method of producing the same - Google Patents

Abstract

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Description

New solid solution phase, heat resistant sintered body and manufacturing method thereof

The relationship between the first turning _{CaZr 4 P 6 O 24 -SrZr 4} P 6 O 24 system (system) and _{CaZr 4 P 6 O 24 -BaZr 4} P 6 O chemical composition and the crystal lattice constant in the employment of the system ₂₄ Graph showing.

2 shows the chemical composition of the solid-state sintered compact of CaZr ₄ P ₆ O ₂₄ -SrZr ₄ P ₆ O ₂₄ system and the coefficient of thermal expansion and four-point bending strength in the temperature range from room temperature to 1400 ° C. Graph showing the relationship.

3 shows the chemical composition of the solid-state sintered compact of CaZr ₄ P ₆ O ₂₄ -BaZr ₄ P ₆ O ₂₄ system and the coefficient of thermal expansion and four-point bending strength in the temperature range from room temperature to 1400 ° C. Graph showing the relationship.

4 is a bar graph showing the weight loss rate in Examples 1-10 and 14-18 and Comparative Examples 21-25 after heat treatment at 1400 ° C. for 100 hours.

5 is a graph showing the relationship between the chemical composition of the solid _- state sintered body of RyZr ₄ Si _X P _6-X O ₂₄ system and the coefficient of thermal expansion in the temperature range from room temperature to 1400 ℃.

6 is a graph showing the relationship between the open porosdity and the four-point bending strength in a solid-state sintered compact of RyZr ₄ Si _X P _6-X O ₂₄ system.

7 is a graph showing a powder x-ray diffraction pattern at room temperature in Example 16.

8 is a graph showing the weight loss rate during heat treatment at 1400 ° C. for 100 hours when various oxides are added to the sintered phosphate compound.

9 is a graph showing the relationship between the amount of PyZr ₄ Si _X P _6υ O phase (phase) in the sintered phosphate compound and the weight loss rate during heat treatment at 1400 ° C. for 100 hours.

10 is a graph showing the relationship between the amount of PyZr ₄ Si _X P _6-X O ₂₄ crystal phase in the sintered phosphate compound and the dimensional change rate during heat treatment at 1400 ° C. for 100 hours.

11 is a graph showing the relationship between the open porosity and the four-point bending strength in the sintered phosphate compound.

12 is a graph showing an x-ray diffraction pattern of the phosphate compound of Example 33.

FIG. 13 shows a method for measuring a self-weight softening percentage.

In the present invention, PyZr ₄ Si _X P _6-X O ₂₄ system (R is one or more elements capable of forming a divalent or trivalent cation, x is a numerical value of 0 or less, y is the electrical neutrality of the formula And a heat-resistant sintered body and a heat-resistant phosphate compound sintered body including the solid solution phase satisfying the conditions of 2/3 or more and 2 or less, respectively, and a method of manufacturing the same, particularly having excellent heat resistance and high temperature stability. RyZr ₄ Si _X P _6-X O ₂₄ A solid solution phase comprising the solid solution phase and the heat-resistant high-strength sintered body having low expansion and high temperature thermal stability and the solid solution phase and having excellent heat resistance, high temperature stability, low expansion, and the like. A sintered phosphate compound and a method for producing the same.

In recent years, with the development of industrial technology, the development of materials having excellent heat resistance and low expandability is strongly demanded.

In response to these demands, zirconyl phosphate [(ZrO) ₂ P ₂ O ₇ ] has been produced as a material having heat resistance and low expandability.

Recently, zirconium phosphates of alkali metals such as sodium and the like have been proposed as materials having heat resistance and coefficient of thermal expansion.

Mat Res. Bull., Vol. 19, 11451-1456 (1984); Journal of Materials Science, 16, 1633-1642 (1981); And 95 (5), 531-537 (1987).

It has also been proposed to have low expansion properties in phosphate compounds of alkaline earth metals with special compositions.

Mat Res. Bull., Vol. 20, 99-160 (1985); And J. Am, Ceram. Soc., 70 [10] C-232 to C-236 (1987).

In addition, US Pat. No. 4,675,302 describes that ceramic materials having a basic composition of Ca _0.5 Ti ₂ P ₃ O ₁₂ have excellent low expansion properties.

However, even though the phosphate compounds such as zirconyl phosphate have the advantage of excellent low expandability, these phosphate compounds have a common problem in that they are pyrolyzed at a high temperature of 1200 ° C. or higher to evaporate phosphorus (P) components.

For example, when the heat treatment is performed at 1400 ° C. for 100 hours, zirconyl phosphate 195 and zirconium phosphate 36 are reduced by 5 by weight.

In addition, the ceramic material described in US Pat. No. 4,675,302 is mainly used as a substrate for low-expansion optical reflectors in which satellites do not undergo deformation or the like under any temperature change.

As shown in FIG. 2 of the patent, the temperature change is about 500 ° C. at most, so that there is no need to consider problems such as stability and heat resistance even at a high temperature of 1200 ° C. or higher. Phosphate compounds such as CaZr ₄ P ₆ O ₂₄ , SrZr ₄ P ₆ O ₂₄ , and Bazr ₄ P ₆ O ₂₄ are superior to zirconyl phosphate in high temperature stability, and the weight loss after heat treatment at 1400 ° C. for 100 hours is 10 % Or less

However, CaZr ₄ P ₆ O ₂₄ has a negative (-) coefficient of thermal expansion and is low in strength, whereas SrZr ₄ P ₆ O ₂₄ is high in strength but relatively high due to a coefficient of thermal expansion of 25 × 10 ⁻⁷ / ° C. It is expandable.

Accordingly, there is a need for development of heat resistant ceramic materials having high strength and low expansion properties.

Meanwhile, Na ₂ CO ₃ , ZrO ₂ , ZrOCl ₂ 8H ₂ O, SiO ₂ , (NH ₄ ) ₂ HPO ₄ , H ₃ PO ₄ , Nb ₂ O ₅ , Y ₂ O ₃ , SrCO ₃ , K ₂ CO ₃ A method using a combination of materials selected from, CaCO ₃ , and the like is known as a method for producing phosphate compounds [T. Oota and I. Yamai, Journal of the American Ceramin Society, 69, 1, (1986)].

In this method, the P ₂ O ₅ component is produced solely during the decomposition of ammonium phosphate to form a locally high concentration of phosphorus and generate a low melting point compound during sintering. As a result, a large space is formed in the binding, which causes a serious defect.

The present inventor has made various studies to solve the problems as described above of the conventional techniques, and is effective in suppressing weight loss due to evaporation of phosphorus (P) component during firing by adding a constant oxide, and in this case, It was found that the crystal phase of was formed in the sintered body.

y

1, R은 2가 또는 3가의 양이온을 형성할 수 있는 하나이상의 원소)의 여러가지 화합물이 전체 고용상을 형성하고, 또한 내열성 및 고온 안정성이 있는 고강도 및 저팽창성 소결체가 고용상을 통하여 열팽창 거동, 열적성질들 등과 같은 RyZr₄P₆O₂₄의 성질들을 제어함으로서 얻어질 수 있을때 우수하다는 것이 발견되었다.In addition, the heat resistance and high temperature stability of the crystalline phase are elements in which R of PyZr ₄ Si _X P _6-X O ₂₄ system can form divalent or trivalent cations such as Ca, Sr, Ba, and Y, and CaZr ₄ P ₆ O RyZr ₄ P ₆ O ₂₄ (2/3), such as ₂₄ , SrZr ₄ P ₆ O ₂₄ , BaZr ₄ P ₆ O _24, etc.

y

1, R is one or more elements that can form divalent or trivalent cations) forms a solid solution phase, and a high-strength and low-expansion sintered body having heat resistance and high temperature stability thermal expansion behavior through the solid solution phase, It has been found to be excellent when it can be obtained by controlling the properties of RyZr ₄ P ₆ O ₂₄ such as thermal properties.

In addition, as shown by the following reaction formula (1), it is possible to form a solid solution in which a part of the P ions are simultaneously substituted with Si ions and R ions,

[n is the valence number of R]

It has been found that heat resistant low expansion materials with heat resistance and strength maintenance and high temperature stability can be obtained by controlling the properties of RyZ ₄ Si _X P _6-X O ₂₄ itself such as thermal expansion behavior, thermal properties, etc. through solid solution dissolution.

As a result, the present invention has been completed.

That is, the present invention is RyZr ₄ Si _X P _6-X O ₂₄ (R is at least one element x capable of forming a divalent or trivalent cation is a numerical value between 0 and 2, y is an electrical neutral condition of the formula A solid solution phase having a composition of 2/3 or more and 2 or less satisfies a value of 2), and a heat-resistant sintered body including the solid solution phase and at least 10% by weight of the solid solution and after heat treatment at 1400 ° C. for 100 hours or less. Sintered heat-resistant phosphate compound having a weight loss ratio of ZrP ₂ O ₇ , (ZrO) ₂ P ₂ O ₂ , ZrO ₂ , Zr (OH) ₄ , ZrSiO ₄ , SiO ₂ , R phosphate, R silicate, and RO (R is an element capable of forming a divalent or trivalent cation) A method for producing a heat-resistant sintered body comprising a solid phase of RyZr ₄ Si _X P _6-X O ₂₄ system comprising molding and firing of a batch mixture selected from ZrP ₂ O ₇ , (ZrO) ₂ P ₂ O ₇ , ZrO ₂ , ZrSiO ₄ , SiO ₂ , Phosphate of R, Silicate of R, and RO (R is divalent or trivalent Provided is a method for producing a heat resistant phosphate compound sintered body comprising molding and firing of a batch mixture selected from elements capable of forming cations).

Preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The solid solution phase of the RyZr ₄ Si _X P _6-X O ₂₄ system according to the present invention can be used not only as a sintered body alone but also as a compound constituting a composite of a heat resistant compound such as zircon, zirconium oxide and the like.

In the solid solution phase of RyZr ₄ Si _X P _6-X O ₂₄ according to the present invention, R is one or more elements capable of forming a divalent or trivalent cation, x is a numerical value of 0 or more and 2 or less, and Y Must be a numerical value between 2/3 and 2 below.

In particular, R is one or more elements belonging to group IIa of the periodicity, that is, elements in barium (Ba), strontium (Sr) and calcium (Ca).

When R contains a monovalent cation, high temperature stability is weakened, while when x is 2 or more, heat resistance is weakened.

When the system meets the above requirements, a solid solution phase having improved heat resistance and high temperature stability and a sintered body comprising the solid solution phase are obtained.

In the phosphate compound according to the present invention, it is necessary to include a substance having a general formula of RyZr ₄ Si _X P _6-X O ₂₄ as a crystal phase.

The thermal stability at high temperature will vary greatly depending on the presence or absence of the above-described crystal phase.

In the sintered body of the present invention, the weight reduction rate and the four-point bending strength due to evaporation of phosphorus (P) components are 10% or less and 100 kg / cm 2 or more at an open porosity of 50% or less after heat treatment at 1400 ° C. for 100 hours. Can be.

In other words, when the open porosity exceeds 50%, the four-point bending strength is less than 100 kg / cm 2, which does not satisfy the required essential bending strength as a practical ceramic material.

In addition, after heat treatment at 1400 ° C. for 5 hours, the self-weight softening rate of the sintered compact was 0.3% or less, which did not satisfy the requirements as a heat resistant material.

In addition, the sintered compact has a small dimensional change rate.

That is, the rate of dimensional change becomes 1% or less after heat treatment at 1400 ° C. for 100 hours, and also does not satisfy the requirements as a heat resistant material. In addition, the thermal expansion coefficient of the sintered body through the temperature range from room temperature to 1400 ° C. is not higher than 25 × 10 ⁻⁷ / ° C., which is a value that can withstand excellent thermal shock.

Accordingly, the sintered bodies according to the present invention having the above properties include, for example, ceramic hexagonal structures such as automobile exhaust purification catalyst carriers; Suitable for materials requiring heat resistance and thermal stability at high temperatures such as rotary heat storage ceramic heat exchangers, heat recovery ceramic heat exchangers, housings for turbocharger rotors, engine manifolds, and heat shields for diesel particulate filters. Lose.

In the method for producing a heat resistant sintered body according to the present invention, the raw material is ZrP ₂ O ₇ , (ZrO) ₂ P ₂ O ₇ , ZrO ₂ , Zr (OH) ₄ , ZrSiO ₄ , SiO ₂ , R phosphate, R and RO Consisting of a mixture of a group of powders selected from silicates (R is an element capable of forming divalent or trivalent cations).

In addition, in the method for producing a sintered phosphate compound according to the present invention, the raw material is ZrP ₂ O ₇ , (ZrO) ₂ P ₂ O ₇ , ZrO ₂ , ZrSiO ₄ , SiO ₂ , R phosphate, R and RO silicates (R Is an element capable of forming divalent or trivalent cations).

Powder materials such as ZrP ₂ O ₇ , (ZrO) ₂ P ₂ O ₇ , ZrO ₂ , Zr (OH) ₄ , ZrSiO ₄ , SiO ₂ , R phosphate, and R and RO silicates are stable compounds and are molded and fired. In the process, it produces little ceramic irregularities and gives excellent heat resistance.

On the other hand, in the case where conventionally used phosphoric acid is used as a P ₂ O ₅ source, since phosphoric acid is a liquid, a nonuniformity causes a high concentration portion of phosphorus to be formed locally during the mixing process, and thus a compound having a low melting point To form.

In addition, when the hexagonal structure is obtained by extruding a structure including phosphoric acid, the extrusion die or cylinder of the extruder is corroded due to the corrosiveness of the phosphoric acid, and as a result, the extrusion becomes difficult.

It is also inherently impossible to mold the structure as a powder due to the presence of phosphoric acid when such a structure is used for press molding.

In the method for producing a heat-resistant sintered body according to the present invention, the batch mixture is usually 0-82.9% by weight of ZrP ₂ O ₇ , 0-79.5% by weight of (ZrO) ₂ P ₂ O ₇ , 0-50.4% by weight of ZrO ₂ , 0-56.8 wt% Zr (OH) ₄ , 0-38.0 wt% ZrSiO ₄ , 0-12.5 wt% SiO ₂ , 0-44.9 wt% R phosphate, 0-35.5 wt% R silicate , And 0-37.3 weight percent RO and the like.

In this case, the batch mixture needs to contain at least one of ZrP ₂ O ₇ , (ZrO) ₂ P ₂ O ₇ , and R phosphate as well as RO, R silicate and R phosphate.

In the method for producing a heat-resistant phosphate compound sintered body according to the present invention, the batch mixture is usually 0-84.2% by weight ZrP ₂ O ₇ , 0-82.3% by weight (ZrO) ₂ P ₂ O ₇ , 0-51.7 weight % ZrO ₂ , 0-77.2 wt% ZrSiO ₄ , 0-37.8 wt% SiO ₂ , 0-44.6 wt% R phosphate, 0-53.0 wt% R silicate, and 0-42.1 wt% It includes RO.

In this case the batch mixture needs to contain not only one or more of ZrP ₂ O ₇ , (ZrO) ₂ P ₂ O ₇ and R phosphate, but also silicates of R and phosphates of R and the like.

RO as a raw material component may be selected and used from stable compounds such as hydroxides, carbonates, sulfates and the like which are converted to RO or oxide during firing.

In addition, raw materials having an average particle size of 50 μm or less are generally used, and a suitable size is 100 μm or less.

As the firing conditions of the sintered compact according to the present invention, the firing temperature is 1400 ° C. or more, the suitable temperature is 1400-1800 ° C., the firing time is 1-24 hours, and the suitable time is 2-10 hours. When the firing temperature is limited to 1400 ° C. or more, a sintered phosphate compound containing 10 wt% or more of RyZr ₄ Si _X P _6-X O ₂₄ as a crystal according to the present invention can be obtained.

In addition, when the firing time is less than 1 hour, the sintering is insufficient, and when the firing time exceeds 24 hours, the strength is lowered due to the growth of abnormal particles, and the precipitation of different phases is caused by the evaporation of phosphorus (P) component. Will occur.

As mentioned above, preferred specific embodiments of the present invention are summarized as follows.

(a) R is two or more elements capable of forming a divalent or trivalent cation, and y is a solid solution of RyZr ₄ P ₆ O _{24 with} a numerical value between 2/3 and 2, satisfying the electrical neutral conditions of the formula. And a heat resistant sintered body and a heat resistant phosphate compound sintered body comprising the solid solution phase.

(b) R is at least one element of Ba, Sr and Ca, x is a numerical value of 0 or more and 2 or less, and y is a solid solution of RyZr ₄ Si _X P _6-X O ₂₄ , which is a numerical value of 1 or more and 2 or less. And a heat resistant sintered body and a heat resistant phosphate compound sintered body comprising the solid solution phase.

(c) A heat resistant sintered body comprising a solid phase of RyZr ₄ Si _X P _6-X O ₂₄ system and having a weight loss rate of 10% or less after heat treatment at 1400 ° C. for 100 hours.

(d) A heat resistant sintered body and a heat resistant phosphate compound sintered body, each containing a solid phase of RyZr ₄ Si _X P _6-X O ₂₄ , having an open porosity of 50% or less and a four-point bending strength of 100 kg / cm 2.

(e) a heat-resistant sintered body and a heat-resistant phosphate compound sintered body each containing a solid phase of RyZr ₄ Si _X P _6-X O ₂₄ system and having a self-softening rate of 0.3% or less after heat treatment at 1400 ° C. for 5 hours.

(f) Heat-resistant sintered bodies and heat-resistant phosphate compound sintered bodies each containing a solid phase of RyZr ₄ Si _X P _6-X O ₂₄ system and having a dimensional change rate of less than 1% after heat treatment at 1400 ° C. for 100 hours.

(g) Heat-resistant sintered bodies and heat-resistant phosphates each containing a solid phase of RyZr ₄ Si _X P _6-X O ₂₄ system and having a coefficient of thermal expansion of 25 x 10 ^-7 / ° C or less over a temperature range from room temperature to 1400 ° C; Compound sintered body.

(h) Heat-resistant sintered bodies and heat-resistant phosphate compound sintered bodies each containing a solid solution phase of RyZr ₄ Si _X P _6-X O ₂₄ for use in a hexagonal structure.

(i) A heat resistant composite comprising a heat-resistant compound such as zircon, zirconium oxide, or the like as a solid crystal phase of the RyZr ₄ Si _X P _6-X O ₂₄ system as the main crystal phase and the second crystal phase.

(j) A method for producing a heat-resistant sintered body and a heat-resistant phosphate compound sintered body comprising a solid _-solution phase of RyZr ₄ Si _X P _6-X O ₂₄ system wherein R is at least one of Ba, Sr and Ca.

(k) A method for producing a heat resistant sintered body and a heat resistant phosphate compound sintered body comprising a solid solution phase of RyZr ₄ Si _X P _6-X O ₂₄ system selected from hydroxides, carbonates, and sulfates in which RO is converted to RO during firing.

(l) A method for producing a heat-resistant sintered body and a heat-resistant phosphate compound sintered body comprising a solid _-solution phase of RyZr ₄ Si _X P _6-X O ₂₄ system having a firing temperature of 1400 ° C. or higher and a firing time of 1-24 hours.

Embodiments of the present invention are described with reference to the table and accompanying drawings, and the present invention is not limited only to the embodiments.

Zirconyl phosphate [(ZrO) ₂ P ₂ O ₇ ], ZrP ₂ O ₇ , calcium carbonate, strontium carbonate, barium carbonate, yttria, which have already been adjusted to a given particle size according to the combination method as shown in Table 1 and Table 2 Nickel oxide, zircon, sodium carbonate, ammonium dihydrogen phosphate, ceria titania, silica, calcium phosphate, zirconia and the like are mixed.

In Comparative Example 25, the mixture shown in Table 1 was charged to an alumina crucible and kept in an electric furnace for 12 hours at 1000 ° C. in the air, and ground to form a batch mixture.

The adjustment of the particle size for zirconyl phosphate is carried out by using a vibration mill full of pebbles of ZrO ₂ sintered body of about 5 mm in diameter, but in a pot and / or attriter It may be done.

The stones of the ZrO ₂ sintered body are used to stabilize MgO and Y ₂ O ₃ .

The chemical composition of the gemstones used is shown in Table 3.

Chemical analyzes of the raw materials used are also shown in Table 4.

100 parts by weight of the batch mixtures shown in Table 1 and Table 2 were added and thoroughly mixed with 5 parts by weight of a 10% PVA aqueous solution and molded at a pressure of 100 kg / cm in a mold of 25 × 80 × 6 mm. After that, the rubber is pressed under a pressure of 2 tons / cm 2 and then dried.

After drying, the molded product is fired in an electric furnace in the air under the conditions shown in Tables 1 and 2.

Heating rate (temperature rise rate) is 5-1700 degreeC / hr.

After firing, the fired sintered body was processed into test pieces of 3 × 4 × 40 mm indicated in JIS R1601 (1981), and then heat-treated at 1400 ° C. for 100 hours, then weight loss rate and dimensional change rate, from room temperature (RT) to 1400 ° C. The coefficient of thermal expansion, four-point bending strength, self-weight softening rate, open porosity, and melting point over the temperature range are measured.

Measurement of the coefficient of thermal expansion is carried out with a push rod type differential expansion system using a high purity alumina sintered body in the temperature range from room temperature (RT) to 1400 ℃.

Four-point bending strength is measured according to the method shown by JISR1601.

) 30㎜의 양 지지점 위에 상기 시험편을 위치시키고 대기중의 1400℃에서 5시간동안 열처리하여 자중 변형량 △X를 측정한 다음 다음의 식에 따라 측정되어지는데 이때:The self-weight softening rate is the length (

) Place the specimens on both support points of 30 mm and heat-treat at 1400 ° C for 5 hours in the air to measure the strain amount ΔX and then measure according to the following equation:

Open porosity is measured by the Archimedes method.

Melting | fusing point is measured by visually observing whether the cut sample of the sintered compact of 3x4x5 mm melts by heat-processing at 1700 degreeC for 10 minutes in an electric furnace.

Also, the amounts of crystal phases in the sintered body are the (200) surface reflection peak value of the zirconyl phosphate (β- (ZrO) ₂ P ₂ O ₇ ) [Communications of the American Ceramic Society, C-80 (1984)], RyZr ₄ Si _X P (113) plane reflection peak value of _6-X O ₂₄ [The index of the composition crystal phase is JCPDS 33-321 of CaZr (PO ₄ ) ₆ , JCPDS 33-1360 of SrSr ₄ (PO) ₆ and BaZr ₄ (PO ₄ ) ₆ After the numerical value is determined according to JCPDS 34-95, it is judged that it is possible to create a solid solution if it is possible to attach an exponent value.] The zircon's (312) plane reflection peak value of JCPDS 6-266, and m-ZrO ₂ It is measured quantitatively by using the (011) plane reflection peak value of JCPDS 34-95, but since the relative intensity of the (011) plane reflection of m-ZrO ₂ is as low as 18/100, the value of 5.6 times this intensity is It is used as the peak value.

As for other kinds of crystal phases, their presence is only identified by the X-ray diffraction pattern.

The lattice constants of the solid solution phases were determined from the (018) plane reflection peak angles 2θ and (208) plane reflection peak angles of RyZr ₄ Si _X P _6-X O ₂₄ , and then the distances d ₁₈ and (d ₂₀₈ ) were measured. It is calculated by calculating a and c according to the system of equations:

TABLE 1a

TABLE 1b

TABLE 1c

TABLE 1d

TABLE 1e

TABLE 1f

Table 1g

Table 1h

TABLE 2a

TABLE 2b

TABLE 3

TABLE 4

As can be seen from the results of Examples 1-19 and Comparative Examples 21-26 of Table 1, the solid solution phase and the solid solution phase of the R _y Zr ₄ Si _X P _6-X O ₂₄ system according to the present invention are included. The heat resistant sintered compact is obtained when R is one or more elements capable of forming a divalent or trivalent cation, and x is a numerical value of 0 or more and 2 or less.

In addition, the solid phase and the sintered body is ZrP ₂ O ₇ , (ZrO) ₂ P ₂ O ₇ , ZrO ₂ , Zr (OH) ₄ , ZrSiO ₄ , SiO ₂ , phosphate of R, silicate of R, and RO (R is 2 A batch mixture of materials selected from valent or trivalent cations) is obtained by sintering under the predetermined conditions shown in Table 1.

1 shows the relationship between chemical composition and lattice constant in solid solution phases of CaZr ₄ P ₆ O ₂₄ -SrZr ₄ P ₆ O ₂₄ and CaZr ₄ P ₆ O ₂₄ -BaZr ₄ P ₆ O ₂₄ have.

FIG. 2 shows the relationship between the chemical composition of the solid solution phase of CaZr ₄ P ₆ O ₂₄ -SrZr ₄ P ₆ P ₂₄ system and the four-point bending strength and thermal expansion coefficient of the sintered compact including the solid solution phase.

3 shows the relationship between the chemical composition in the solid solution phase of CaZr ₄ P ₆ O ₂₄ -BaZr ₄ P ₆ P ₂₄ system and the four-point bending strength and thermal expansion coefficient of the sintered compact including the solid solution phase.

4 shows the relationship between the chemical composition of the solid solution phase of R _y Zr ₄ Si _X P _6-X O ₂₄ system and the weight reduction rate when the sintered compact including the solid solution phase is maintained at 1400 ° C. for 100 hours. In Fig. 5, the relationship between the chemical composition in the solid solution phase of the R _y Zr ₄ Si _X P _6-X O ₂₄ system and the thermal expansion coefficient of the sintered compact including the solid solution phase is shown.

y

1) 고용상 자체의 특성들이 유지되어질 수 있으며 또한 우수한 내열성 및 고온 안정성을 갖는 고강도 저팽창 소결체들이 얻어질 수 있다.As described above, when R is at least one element capable of forming a divalent or trivalent cation, it is excellent in heat resistance and high temperature stability of the crystalline phase, and furthermore, R _y Zr ₄ P ₆ O ₂₄ (2/3

y

1) The properties of solid solution itself can be maintained and high strength low expansion sintered bodies with excellent heat resistance and high temperature stability can be obtained.

In addition, the solid solution phase in which a portion of P ions are simultaneously substituted with Sr ions and R ions is more excellent in high temperature stability, and the characteristics of the solid solution phase of R _y Zr ₄ Si _X P _6-X O ₂₄ system can be controlled. A heat resistant sintered body having further improved high temperature stability, high strength and low expansion properties is obtained.

6 shows the relationship between the open porosity and the four-point bending strength in the sintered compact including the solid solution phase of R _y Zr ₄ Si _X P _6-X -O ₂₄ system.

FIG. 7 shows a powder X-ray diffraction pattern at room temperature (RT) of the sintered compact of Example 16 and shows that it is a sintered compact composed only of a solid-phase single phase of Sr _1.5 Zr ₄ SiP ₆ O ₂₄ .

As can be seen from the results of Examples 2, 6, 9, 10, 16 of Table 1 and Comparative Examples 21-24, and Examples 31-37 and Comparative Examples 41-48 of Table 2, R _y Zr ₄ When Si _X P _6-X O ₂₄ (R is one or more elements capable of forming a divalent or trivalent cation) is contained in an amount of 10% by weight or more as a crystalline phase, after heat treatment at 1400 ° C. for 100 hours, 10 Phosphate compound sintered bodies having a weight reduction rate of less than or equal to% are obtained.

These sinters were also selected from ZrP ₂ O ₇ , (ZrO) ₂ P ₂ O ₇ , ZrO ₂ , ZrSiO ₄ , SiO ₂ , phosphates of R, silicates of R and RO under the sintering conditions shown in Tables 1 and 2 Obtained by sintering a batch mixture of materials.

FIG. 8 shows the weight reduction rate when various oxides are added to the phosphate compound, and FIG. 9 shows the weight percentage of the R _y Zr ₄ Si _X P _6-X O ₂₄ system and the sintered body contained in the phosphate compound. The relationship between the weight loss rates is shown.

In FIG. 10, the relationship between the weight percentage of the R _y Zr ₄ Si _X P _6-X O ₂₄ crystal phase and the dimensional change rate in the sintered phosphate compound is shown.

As described above, when more than 10 wt% of R _y Zr ₄ Si _X P _6-X O ₂₄ crystal phase is included in the sintered phosphate compound, the rate of dimensional change and weight loss after heat treatment at 1400 ° C. for 100 hours are considerably small and the heat resistance is high. It is excellent in the sintered phosphate compound.

11 shows the relationship between the open porosity and the four-point bending strength in the sintered phosphate compound.

FIG. 12 shows an X-ray diffraction pattern of a sintered phosphate compound sintered to clearly include (ZrO) ₂ P ₂ O ₇ and CaZr ₄ (PO ₄ ) ₆ as crystal phases in Example 33. FIG.

As described above, according to the present invention, R _y Zr ₄ Si _X P _6-X O ₂₄ system (R is one or more elements capable of forming a divalent or trivalent cation, and x is a numerical value of 0 or more and 2 or less. and y is a numerical value of 2/3 or more to satisfy the electrical neutral condition of the chemical formula), and a heat-resistant sintered body including the solid solution phase and the high strength, low expandability and excellent high temperature stability, etc. A heat resistant phosphate compound sintered body including at least% by weight and having a weight reduction rate of 10% or less after heat treatment at 1400 ° C. for 100 hours can be obtained.

Therefore, the solid heat phase of the R _y Zr ₄ Si _X P _6-X O ₂₄ system and the heat-resistant sintered body and the phosphate compound sintered body including the solid-solution phase are formed in a hexagonal structure by extrusion molding. Heat-resistant, low-expansion and high temperatures, such as diesel particulate filters and housings for ceramic turbocharger rotors or thermal barriers for engine manifolds, are also used when molded through slip molding, compression and injection molding. It can be widely applied to products requiring stability.

Claims (6)

R is one or more elements capable of forming a divalent or trivalent cation, x is a numerical value of 0 or more and 2 or less, and R is a numerical value of 2/3 or more and 2 or less that satisfies the electrical neutral condition of the chemical formula _y Zr ₄ Si _X P _6-X O ₂₄ A solid solution characterized by having a composition. R is one or more elements capable of forming a divalent or trivalent cation, x is a numerical value of 0 or more and 2 or less, and R is a numerical value of 2/3 or more and 2 or less that satisfies the electrical neutral condition of the chemical formula _y A heat resistant sintered compact comprising a solid solution phase of Zr ₄ Si _X P _6-X O ₂₄ system. R is one or more elements capable of forming a divalent or trivalent cation, x is a numerical value of 0 or more and 2 or less, and R is a numerical value of 2/3 or more and 2 or less that satisfies the electrical neutral condition of the chemical formula _y Zr ₄ Si _X P _6-X O _{24 It} comprises a solid solution of more than 10% by weight, heat-resistant phosphate compound sintered body characterized in that having a weight loss rate of less than 10% after heat treatment at 1400 ℃ for 100 hours. As the main crystalline phase of the sintered body, R is one or more elements capable of forming a divalent or trivalent cation, x is a numerical value of 0 or more and 2 or less, and y is 2/3 or more and 2 or less which satisfies the electrical neutral condition of the chemical formula ZrP ₂ O ₇ , (ZrO) ₂ P ₂ O ₇ , ZrO ₂ , Zr (OH) ₄ , ZrSiO ₄ , to precipitate the solid solution phase of R _y Zr ₄ Si _X P _6-X O ₂₄ A heat-resistant sintered body comprising the steps of forming and firing a batch mixture of materials selected from SiO ₂ , phosphates of R, silicates of R, and RO (R is an element capable of forming divalent or trivalent cations). Manufacturing method. R is one or more elements capable of forming a divalent or trivalent cation, x is a numerical value of 0 or more and 2 or less, and R is a numerical value of 2/3 or more and 2 or less that satisfies the electrical neutral condition of the chemical formula _y Zr ₄ Si _X P _6-X O ₂₄ ZrP ₂ O ₇ , (ZrO) ₂ P ₂ O ₇ , ZrO ₂ , ZrSiO ₄ , SiO ₂ , Preparation of a heat resistant phosphate compound sintered body comprising the step of forming and firing a batch mixture of materials selected from phosphates of R, silicates of R, and RO (R is an element capable of forming divalent or trivalent cations) Way. The method according to claim 4 or 5, wherein the firing step is performed at a temperature of 1400 ° C or higher for 1 hour to 24 hours.

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