阅读说明：本技术 一种硅酸锆复合陶瓷辊棒及其制备方法 (Zirconium silicate composite ceramic roller and preparation method thereof ) 是由 刘溧 钱东琴 章杰 于 2021-10-08 设计创作，主要内容包括：本发明公开了一种硅酸锆复合陶瓷辊棒及其制备方法,该陶瓷辊棒由改性硅酸锆颗粒和强化纤维共混压制制得,改性硅酸锆颗粒通过改性剂处理,使岛状结构变形,[SiO-(4)]四面体和[ZrO-(8)]十二面体脱离。SiO-(2)-Al-(2)O-(3)复合氧化物具有更稳定的结构,通过添加剂的控制,使[SiO-(4)]四面体,[AlO-(6)]八面体在一定条件下形成紧密连接的球形结构,这种球形结构与[ZrO-(8)]十二面体重新复合,形成环[ZrO-(8)]十二面体岛状结构,硅酸锆的岛状结构不变,增加了辊棒的耐高温性、耐磨性、韧性,强化纤维表面的十七氟癸基层为疏水层,能够有效地防止陶瓷辊棒吸收空气中水分,避免了陶瓷辊棒在使用时出现裂痕。(The invention discloses a zirconium silicate composite ceramic roller and a preparation method thereof, the ceramic roller is prepared by blending and pressing modified zirconium silicate particles and reinforcing fibers, the modified zirconium silicate particles are treated by a modifier to deform island-shaped structures, [ SiO ] 4 ]Tetrahedra and [ ZrO ] 8 ]The dodecahedron is detached. SiO 2 2 ‑Al 2 O 3 The composite oxide has a more stable structure, and the [ SiO ] is controlled by the additive 4 ]Tetrahedron, [ AlO 6 ]Octahedron forms a tightly connected spherical structure under certain conditions, and the spherical structure is connected with [ ZrO ] 8 ]The dodecahedron is recombined to form the ring [ ZrO ] 8 ]Island-shaped structure of dodecahedron, island-shaped structure of zirconium silicateAnd the high temperature resistance, the wear resistance and the toughness of the roller rod are improved, and the heptadecafluorodecyl base layer on the surface of the reinforcing fiber is a hydrophobic layer, so that the ceramic roller rod can be effectively prevented from absorbing moisture in the air, and cracks are avoided when the ceramic roller rod is used.)

1. The zirconium silicate composite ceramic roller is characterized in that: the feed comprises the following raw materials in parts by weight: 95-100 parts of modified zirconium silicate particles and 3-5 parts of reinforcing fibers;

the reinforced fiber is prepared by the following steps:

step B1: uniformly mixing potassium persulfate, phosphorus pentoxide and concentrated sulfuric acid, adding graphite, stirring, washing with deionized water to be neutral, performing vacuum drying to obtain pre-oxidized graphite, dissolving the pre-oxidized graphite in the concentrated sulfuric acid, adding potassium permanganate, reacting, adding deionized water, standing, adding hydrogen peroxide until the reaction solution is bright yellow, washing with the deionized water to be neutral, washing with acetone and concentrated hydrochloric acid for 3 times in sequence, washing again to be neutral, and performing vacuum drying to obtain graphene oxide;

step B2: dispersing graphene oxide in deionized water, carrying out ultrasonic treatment, adding tetrabutyl titanate and ethanol, stirring, adding acetic acid, heating for reaction, filtering to remove filtrate, and roasting a filter cake to obtain pre-modified graphene;

step B3: dispersing pre-modified graphene in ethanol, stirring, adding heptadecafluorodecyltriethoxysilane and deionized water, adjusting the pH value of a reaction solution, reacting to obtain modified graphene, mixing and reacting carbon fiber, potassium persulfate, silver nitrate and deionized water, adding ethylenediamine, modified graphene and 1-hydroxybenzotriazole, and performing ultrasonic treatment to obtain the reinforced fiber.

2. The zirconium silicate composite ceramic roller of claim 1, wherein: the using amount ratio of the potassium persulfate, the phosphorus pentoxide, the concentrated sulfuric acid and the graphite in the step B1 is 1g to 5mL to 0.5g, the using amount ratio of the pre-oxidized graphite, the concentrated sulfuric acid, the potassium permanganate, the deionized water and the hydrogen peroxide is 1.5g to 30mL to 3g to 50mL to 3mL, the mass fractions of the concentrated sulfuric acid, the concentrated hydrochloric acid and the hydrogen peroxide are 98%, 36% and 30%.

3. The zirconium silicate composite ceramic roller of claim 1, wherein: the dosage ratio of the graphene oxide, the deionized water, the tetrabutyl titanate, the ethanol and the acetic acid in the step B2 is 1g:80mL:6mL:30mL:5 mL.

4. The zirconium silicate composite ceramic roller of claim 1, wherein: the dosage ratio of the pre-modified graphene and the heptadecafluorodecyltriethoxysilane in the step B3 is 1g:3mL, and the dosage ratio of the carbon fiber, the potassium persulfate, the silver nitrate, the deionized water, the ethylenediamine, the modified graphene and the 1-hydroxybenzotriazole is 1g:2g:2g:20mL:1.5mL:0.8g:1.2 g.

5. The preparation method of the zirconium silicate composite ceramic roller rod according to claim 1, characterized in that: the method specifically comprises the following steps:

uniformly blending the modified zirconium silicate particles, the reinforcing fibers and the polyvinyl alcohol, then pressing and molding under the condition that the pressure is 25-35MPa, and then sintering and preserving heat for 2-3h under the condition that the temperature is 1570-1580 ℃ to obtain the high-temperature resistant roller.

Technical Field

The invention relates to the technical field of roller rod preparation, in particular to a zirconium silicate composite ceramic roller rod and a preparation method thereof.

Background

The roller kiln has the characteristics of small firing temperature difference, short firing period, high yield, low energy consumption, easy control and the like, and is widely applied to the industries of building sanitary ceramics (particularly wall and floor tiles and sanitary wares), household ceramics, special ceramics and ferrite, glass, metal annealing and the like. With the increasing expansion of the application range of roller kilns, the requirements on the manufacturing technology and the used refractory materials of the roller kilns are continuously increased.

In the roller kiln, the roller is the most critical refractory material and plays a role in bearing and conveying products in the kiln, namely the strength and high-temperature mechanical property of the roller determine the service temperature and the loading capacity of the roller kiln, and further determine the service range of the roller kiln, so that the key point for further popularization and application of the roller kiln is to research the performance of the roller by using materials for manufacturing the roller to improve the performance of the roller.

Disclosure of Invention

The invention aims to provide a zirconium silicate composite ceramic roller and a preparation method thereof, which solve the problem that the mechanical property of the ceramic roller used at the present stage is reduced under the high-temperature condition through modified zirconium silicate particles and reinforcing fibers, and simultaneously, the ceramic roller is easy to crack at the high temperature due to higher water absorption.

The purpose of the invention can be realized by the following technical scheme:

a zirconium silicate composite ceramic roller comprises the following raw materials in parts by weight: 95-100 parts of modified zirconium silicate particles and 3-5 parts of reinforcing fibers;

the zirconium silicate composite ceramic roller is prepared by the following steps:

uniformly blending the modified zirconium silicate particles, the reinforcing fibers and the polyvinyl alcohol, then pressing and molding under the condition that the pressure is 25-35MPa, and then sintering and preserving heat for 2-3h under the condition that the temperature is 1570-1580 ℃ to obtain the high-temperature resistant roller.

The modified zirconium silicate particles are prepared by the following steps:

step A1: uniformly mixing zirconium silicate, a modifier and a sodium chloride aqueous solution, and performing ball milling for 3-5 hours to prepare a mixture;

step A2: and (3) firing the mixture at the temperature of 1570-.

Furthermore, the size of the modified zirconium silicate particles is D50:1.6-2.0 μm, D97:2.0-3.0 μm, the number of particles smaller than 2 μm is more than or equal to 85 percent, and the specific surface area of the modified zirconium silicate particles is 5.0-10.0m²/c.c.。

Further, the modifier comprises the following raw materials: ZrO (ZrO)₂≥64.0%、SiO₂≤35.0%、Al₂O₃≤3.0%、CaO+MgO≤0.1%、K₂O≤0.1%、Na₂O≤0.1%、Fe₂O₃+TiO₂≤0.5%。

Further, the reinforced fiber is prepared by the following steps:

step B1: adding potassium persulfate, phosphorus pentoxide and concentrated sulfuric acid into a reaction kettle, stirring at the rotation speed of 200-90 ℃ until the potassium persulfate and the phosphorus pentoxide are completely dissolved, adding graphite, continuously stirring for 5-8h, cooling to the temperature of 25-30 ℃, washing with deionized water to neutrality, vacuum drying to obtain pre-oxidized graphite, dissolving the pre-oxidized graphite in the concentrated sulfuric acid, adding potassium permanganate at the temperature of 3-5 ℃, reacting at the temperature of 35-40 ℃ for 2-3h, adding deionized water, standing for 5-10min, adding hydrogen peroxide until the reaction solution is bright yellow, washing with deionized water to neutrality, washing with acetone and concentrated hydrochloric acid for 3 times in sequence, washing again to neutrality, vacuum drying to obtain graphene oxide;

step B2: dispersing graphene oxide in deionized water, carrying out ultrasonic treatment for 2-3h under the condition of frequency of 40-60kHz, adding tetrabutyl titanate and ethanol, stirring for 5-10min under the condition of rotation speed of 200-70 ℃ and 300r/min, adding acetic acid, reacting for 2-3h under the condition of temperature of 60-70 ℃, filtering to remove filtrate, and roasting a filter cake for 2-3h under the condition of temperature of 500-550 ℃ to obtain pre-modified graphene;

step B3: dispersing pre-modified graphene in ethanol, stirring and adding heptadecafluorodecyltriethoxysilane and deionized water under the conditions of a rotation speed of 200-80 ℃ and a temperature of 70-80 ℃, adjusting the pH value of a reaction solution to 3-4, reacting for 2-4h, filtering to remove filtrate to obtain modified graphene, adding carbon fiber, potassium persulfate, silver nitrate and deionized water into a reaction kettle, reacting for 2-3h under the conditions of a rotation speed of 150-200r/min and a temperature of 80-90 ℃, adding ethylenediamine, modified graphene and 1-hydroxybenzotriazole, and ultrasonically treating for 3-4h under the conditions of a temperature of 50-60 ℃ and a frequency of 60-80kHz to remove the filtrate to obtain the reinforced fiber.

Further, in the step B1, the dosage ratio of the potassium persulfate, the phosphorus pentoxide, the concentrated sulfuric acid and the graphite is 1g:1g:5mL:0.5g, the dosage ratio of the pre-oxidized graphite, the concentrated sulfuric acid, the potassium permanganate, the deionized water and the hydrogen peroxide is 1.5g:30mL:3g:50mL:3mL, the mass fractions of the concentrated sulfuric acids are 98%, the mass fraction of the concentrated hydrochloric acid is 36%, and the mass fraction of the hydrogen peroxide is 30%.

Further, the dosage ratio of the graphene oxide, the deionized water, the tetrabutyl titanate, the ethanol and the acetic acid in the step B2 is 1g:80mL:6mL:30mL:5 mL.

Further, the dosage ratio of the pre-modified graphene and the heptadecafluorodecyltriethoxysilane in the step B3 is 1g:3mL, and the dosage ratio of the carbon fiber, the potassium persulfate, the silver nitrate, the deionized water, the ethylenediamine, the modified graphene and the 1-hydroxybenzotriazole is 1g:2g:2g:20mL:1.5mL:0.8g:1.2 g.

The invention has the beneficial effects that:

the zirconium silicate composite ceramic roller prepared by the invention is prepared by blending and pressing modified zirconium silicate particles and reinforcing fibers, wherein the modified zirconium silicate particles are treated by a modifier to deform island-shaped structures, [ SiO ]₄]Tetrahedra and [ ZrO ]₈]The dodecahedron is detached. SiO 2₂-Al₂O₃The composite oxide has a more stable structure, and the [ SiO ] is controlled by the additive₄]Tetrahedron, [ AlO₆]The octahedron forms a tightly connected spherical structure under certain conditions, and the structure isSpherical structure and [ ZrO ]₈]The dodecahedron is recombined to form the ring [ ZrO ]₈]The roll rod is provided with a dodecahedron island-shaped structure, the island-shaped structure of zirconium silicate is unchanged, the high temperature resistance, the wear resistance and the toughness of the roll rod are improved, the reinforced fiber is prepared, graphite is used as a raw material for oxidation treatment to prepare graphene oxide, the graphene oxide is treated by tetrabutyl titanate to enable the surface of the graphene oxide to be embedded with nano titanium dioxide to prepare pre-modified graphene, heptadecafluorodecyltriethoxysilane is hydrolyzed to react with active hydroxyl on the surface of the nano titanium dioxide on the modified graphene to enable the surface to form a heptadecafluorodecyl base layer, then carbon fiber is treated to prepare carbon oxide fiber, ethylene diamine is used for crosslinking and blending the carbon fiber and the modified graphene to prepare the reinforced fiber, the toughness of the ceramic roll rod is further improved, and meanwhile, the heptadecafluorodecyl layer on the surface is a hydrophobic layer, so that the ceramic roll rod can effectively prevent the water in the air from being absorbed, the ceramic roller is prevented from cracking in use.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

A zirconium silicate composite ceramic roller comprises the following raw materials in parts by weight: 95 parts of modified zirconium silicate particles and 3 parts of reinforcing fibers;

the zirconium silicate composite ceramic roller is prepared by the following steps:

uniformly blending the modified zirconium silicate particles, the reinforcing fibers and the polyvinyl alcohol, pressing and molding under the condition that the pressure is 25MPa, and sintering and keeping the temperature for 2 hours at the temperature of 1570 ℃ to obtain the high-temperature resistant roller rod.

The modified zirconium silicate particles are prepared by the following steps:

step A1: uniformly mixing zirconium silicate, a modifier and a sodium chloride aqueous solution, and performing ball milling for 3 hours to prepare a mixture;

step A2: and firing the mixture at 1570 ℃ for 1h to obtain the modified zirconium silicate particles.

The modifier comprises the following raw materials: ZrO (ZrO)₂ 64.0%、SiO₂ 35.0、Al₂O₃ 0.2%、CaO+MgO 0.1%、K₂O 0.1%、Na₂O 0.1%、Fe₂O₃+TiO₂ 0.5%。

The reinforced fiber is prepared by the following steps:

step B1: adding potassium persulfate, phosphorus pentoxide and concentrated sulfuric acid into a reaction kettle, stirring at the rotation speed of 200r/min and the temperature of 80 ℃ until the potassium persulfate and the phosphorus pentoxide are completely dissolved, adding graphite, continuously stirring for 5h, cooling to the temperature of 25 ℃, washing with deionized water to be neutral, carrying out vacuum drying to obtain pre-oxidized graphite, dissolving the pre-oxidized graphite in the concentrated sulfuric acid, adding potassium permanganate at the temperature of 3 ℃, reacting for 2h at the temperature of 35 ℃, adding deionized water, standing for 5min, adding hydrogen peroxide until the reaction liquid is bright yellow, washing with the deionized water to be neutral, washing with acetone and concentrated hydrochloric acid for 3 times in sequence, washing again to be neutral, and carrying out vacuum drying to obtain graphene oxide;

step B2: dispersing graphene oxide in deionized water, carrying out ultrasonic treatment for 2h under the condition of 40kHz frequency, adding tetrabutyl titanate and ethanol, stirring for 5min under the condition of 200r/min of rotation speed, adding acetic acid, reacting for 2h under the condition of 60 ℃, filtering to remove filtrate, and roasting a filter cake for 2h under the condition of 500 ℃ to obtain pre-modified graphene;

step B3: dispersing pre-modified graphene in ethanol, stirring and adding heptadecafluorodecyltriethoxysilane and deionized water under the conditions of a rotating speed of 200r/min and a temperature of 70 ℃, adjusting the pH value of a reaction solution to be 3, reacting for 2 hours, filtering to remove filtrate to obtain modified graphene, adding carbon fiber, potassium persulfate, silver nitrate and deionized water into a reaction kettle, reacting for 2 hours under the conditions of a rotating speed of 150r/min and a temperature of 80 ℃, adding ethylenediamine, modified graphene and 1-hydroxybenzotriazole, ultrasonically treating for 3 hours under the conditions of a temperature of 50 ℃ and a frequency of 60kHz, filtering to remove filtrate, and obtaining the reinforced fiber.

Example 2

A zirconium silicate composite ceramic roller comprises the following raw materials in parts by weight: 98 parts of modified zirconium silicate particles and 4 parts of reinforcing fibers;

the zirconium silicate composite ceramic roller is prepared by the following steps:

after uniformly blending the modified zirconium silicate particles, the reinforcing fibers and the polyvinyl alcohol, pressing and forming under the condition that the pressure is 30MPa, and preparing the modified zirconium silicate particles at the temperature of 1575 by the following steps:

step A1: uniformly mixing zirconium silicate, a modifier and a sodium chloride aqueous solution, and performing ball milling for 4 hours to prepare a mixture;

step A2: and firing the mixture at 1575 ℃ for 2h to obtain the modified zirconium silicate particles.

The modifier comprises the following raw materials: ZrO (ZrO)₂ 76.2%、SiO₂ 20.0%、Al₂O₃ 3.0%、CaO+MgO 0.1%、K₂O 0.1%、Na₂O 0.1%、Fe₂O₃+TiO₂ 0.5%。

The reinforced fiber is prepared by the following steps:

step B1: adding potassium persulfate, phosphorus pentoxide and concentrated sulfuric acid into a reaction kettle, stirring at the rotation speed of 300r/min and at the temperature of 85 ℃ until the potassium persulfate and the phosphorus pentoxide are completely dissolved, adding graphite, continuously stirring for 6 hours, cooling to the temperature of 28 ℃, washing with deionized water to be neutral, carrying out vacuum drying to obtain pre-oxidized graphite, dissolving the pre-oxidized graphite in the concentrated sulfuric acid, adding potassium permanganate at the temperature of 4 ℃, reacting at the temperature of 38 ℃ for 2.5 hours, adding deionized water, standing for 8 minutes, adding hydrogen peroxide until the reaction solution is bright yellow, washing with the deionized water to be neutral, washing with acetone and concentrated hydrochloric acid for 3 times in sequence, washing again to be neutral, and carrying out vacuum drying to obtain graphene oxide;

step B2: dispersing graphene oxide in deionized water, carrying out ultrasonic treatment for 2.5h under the condition of 50kHz, adding tetrabutyl titanate and ethanol, stirring for 8min under the condition of 200r/min of rotation speed, adding acetic acid, reacting for 2.5h under the condition of 65 ℃, filtering to remove filtrate, and roasting a filter cake for 2.5h under the condition of 530 ℃ to obtain pre-modified graphene;

step B3: dispersing pre-modified graphene in ethanol, stirring and adding heptadecafluorodecyltriethoxysilane and deionized water under the conditions of the rotating speed of 300r/min and the temperature of 75 ℃, adjusting the pH value of a reaction solution to be 4, reacting for 3 hours, filtering to remove filtrate to obtain modified graphene, adding carbon fiber, potassium persulfate, silver nitrate and deionized water into a reaction kettle, reacting for 2.5 hours under the conditions of the rotating speed of 180r/min and the temperature of 85 ℃, adding ethylenediamine, modified graphene and 1-hydroxybenzotriazole, ultrasonically treating for 3.5 hours under the conditions of the temperature of 55 ℃ and the frequency of 70kHz, filtering to remove filtrate, and obtaining the reinforced fiber.

Example 3

A zirconium silicate composite ceramic roller comprises the following raw materials in parts by weight: 100 parts of modified zirconium silicate particles and 5 parts of reinforcing fibers;

the zirconium silicate composite ceramic roller is prepared by the following steps:

uniformly blending the modified zirconium silicate particles, the reinforcing fibers and the polyvinyl alcohol, pressing and molding under the condition that the pressure is 35MPa, and then sintering and preserving heat for 3 hours at the temperature of 1580 ℃ to obtain the high-temperature resistant roller.

The modified zirconium silicate particles are prepared by the following steps:

step A1: uniformly mixing zirconium silicate, a modifier and a sodium chloride aqueous solution, and performing ball milling for 5 hours to prepare a mixture;

step A2: and (3) firing the mixture at 1580 ℃ for 3h to obtain the modified zirconium silicate particles.

The modifier comprises the following raw materials: ZrO (ZrO)₂ 87.2%、SiO₂ 10.0%、Al₂O₃ 2.0%、CaO+MgO 0.1%、K₂O 0.1%、Na₂O 0.1%、Fe₂O₃+TiO₂ 0.5%。

The reinforced fiber is prepared by the following steps:

step B1: adding potassium persulfate, phosphorus pentoxide and concentrated sulfuric acid into a reaction kettle, stirring at the rotation speed of 300r/min and the temperature of 90 ℃ until the potassium persulfate and the phosphorus pentoxide are completely dissolved, adding graphite, continuously stirring for 8h, cooling to the temperature of 30 ℃, washing with deionized water to be neutral, carrying out vacuum drying to obtain pre-oxidized graphite, dissolving the pre-oxidized graphite in the concentrated sulfuric acid, adding potassium permanganate at the temperature of 5 ℃, reacting at the temperature of 40 ℃ for 3h, adding deionized water, standing for 10min, adding hydrogen peroxide until the reaction liquid is bright yellow, washing with the deionized water to be neutral, washing with acetone and concentrated hydrochloric acid for 3 times in sequence, washing again to be neutral, and carrying out vacuum drying to obtain graphene oxide;

step B2: dispersing graphene oxide in deionized water, carrying out ultrasonic treatment for 3h under the condition of 60kHz, adding tetrabutyl titanate and ethanol, stirring for 10min under the condition of 300r/min of rotation speed, adding acetic acid, reacting for 3h under the condition of 70 ℃, filtering to remove filtrate, and roasting a filter cake for 3h under the condition of 550 ℃ to obtain pre-modified graphene;

step B3: dispersing pre-modified graphene in ethanol, stirring and adding heptadecafluorodecyltriethoxysilane and deionized water under the conditions of a rotating speed of 300r/min and a temperature of 80 ℃, adjusting the pH value of a reaction solution to be 4, reacting for 4 hours, filtering to remove filtrate to obtain modified graphene, adding carbon fiber, potassium persulfate, silver nitrate and deionized water into a reaction kettle, reacting for 3 hours under the conditions of a rotating speed of 200r/min and a temperature of 90 ℃, adding ethylenediamine, modified graphene and 1-hydroxybenzotriazole, ultrasonically treating for 4 hours under the conditions of a temperature of 60 ℃ and a frequency of 80kHz, filtering to remove filtrate, and obtaining the reinforced fiber.

Comparative example 1

This comparative example compared with example 1, in which zirconium silicate particles were used instead of the modified zirconium silicate particles, the remaining steps were the same.

Comparative example 2

This comparative example compared to example 1, in which carbon fibers were used instead of reinforcing fibers, the rest of the procedure was the same.

Comparative example 3

This comparative example is a ceramic stick disclosed in chinese patent CN 108975923A.

The roll rods of examples 1-3 and comparative examples 1-3 were tested for flexural strength in the environment of 1200, 1300 and 1400 ℃ according to the GB/T4741-1999 standard, rapidly heated to 1200 ℃ and then cooled to room temperature in the environment of 50% air humidity, and then cycled for 20, 30 and 50 times to observe whether cracks appear in the ceramic roll rods, the results are shown in the following table;

example 1

Example 2

Example 3

Comparative example 1

Comparative example 2

Comparative example 3

Flexural Strength (MPa) at 1200 DEG C

56

55

57

42

37

47

Bending Strength (MPa) at 1300 ℃

57

56

57

38

31

45

Flexural Strength (MPa) at 1400 ℃

57

57

56

35

28

36

Circulating for 20 times

No occurrence of cracks

No occurrence of cracks

No occurrence of cracks

Occurrence of cracks

Occurrence of cracks

No occurrence of cracks

Circulating for 30 times

No occurrence of cracks

No occurrence of cracks

No occurrence of cracks

Occurrence of cracks

Occurrence of cracks

Occurrence of cracks

Circulating for 50 times

No occurrence of cracks

No occurrence of cracks

No occurrence of cracks

Occurrence of cracks

Occurrence of cracks

Occurrence of cracks

From the above table, it is understood that the bending strengths of the ceramic rods obtained in examples 1 to 3 at temperatures of 1200, 1300 and 1400 ℃ respectively do not change significantly, while the bending strengths of the ceramic rods obtained in comparative examples 1 to 3 decrease significantly, and sudden heating does not affect the ceramic rods obtained in examples 1 to 3 at a high air humidity, indicating that the ceramic rods of the present invention have good mechanical properties and do not absorb water.

The foregoing is merely exemplary and illustrative of the principles of the present invention and various modifications, additions and substitutions of the specific embodiments described herein may be made by those skilled in the art without departing from the principles of the present invention or exceeding the scope of the claims set forth herein.