Self-healing ceramic material with reduced porosity and method for preparing the same

Abstract

The present invention provides a self-healing ceramic material with reduced porosity and a method for preparing the same. The self-healing ceramic material comprises the following components by volume: 60-85 parts by volume of Al.sub.2O.sub.3, 10-20 parts by volume of TiN, 10-20 parts by volume of TiSi.sub.2, 0.1-1 parts by volume of MgO, and 0.1-1 parts by volume of Y.sub.2O.sub.3. Wherein, Al.sub.2O.sub.3 serves as a matrix, TiN and TiSi.sub.2 act as repair agents, and MgO and Y.sub.2O.sub.3 function as sintering aids. The repair function is realized by adding TiN and TiSi.sub.2, which have repair capabilities, to the ceramic matrix, enabling the ceramic material to heal cracks. TiN plays the main role of repair function, and TiSi.sub.2 assists in the repair and helps reduce the formation of surface pores.

Claims

1. A self-healing ceramic material with reduced porosity, comprising the following components by volume: 60-85 parts by volume of Al.sub.2O.sub.3, 10-20 parts by volume of TiN, 10-20 parts by volume of TiSi.sub.2, 0.1-1 parts by volume of MgO, and 0.1-1 parts by volume of Y.sub.2O.sub.3.

2. The self-healing ceramic material according to claim 1, wherein comprising the following components by volume: 65-70 parts by volume of Al.sub.2O.sub.3, 15-20 parts by volume of TiN, 13-18 parts by volume of TiSi.sub.2, 0.3-0.8 parts by volume of MgO, and 0.3-0.8 parts by volume of Y.sub.2O.sub.3.

3. The self-healing ceramic material according to claim 1, wherein comprising the following components by volume: 67-68 parts by volume of Al.sub.2O.sub.3, 16-17 parts by volume of TiN, 14-16 parts by volume of TiSi.sub.2, 0.4-0.6 parts by volume of MgO, and 0.4-0.6 parts by volume of Y.sub.2O.sub.3.

4. The self-healing ceramic material according to claim 1, wherein comprising the following components by volume: 67.2 parts by volume of Al.sub.2O.sub.3, 16.8 parts by volume of TiN, 15 parts by volume of TiSi.sub.2, 0.5 parts by volume of MgO, and 0.5 parts by volume of Y.sub.2O.sub.3.

5. The self-healing ceramic material according to claim 1, wherein an average particle size of Al.sub.2O.sub.3 powder is 0.5-1 m, an average particle size of TiN powder is 0.5-1 m, an average particle size of Y.sub.2O.sub.3 powder is 1-3 m, and an average particle size of MgO powder is 0.4-0.7 m.

6. A method for preparing the self-healing ceramic material according to claim 1, comprising: proportionally measuring Al.sub.2O.sub.3, TiN, and TiSi.sub.2 powders and adding anhydrous ethanol and a dispersant to each component, ultrasonically dispersing the components to prepare individual suspensions of Al.sub.2O.sub.3, TiN, and TiSi.sub.2, mixing the three suspensions to form a composite phase suspension; and proportionally adding MgO and Y.sub.2O.sub.3 powders to the composite phase suspension, ultrasonically dispersing, then ball milling in an inert atmosphere, followed by drying, sieving, pre-pressing, and sintering in a spark plasma sintering furnace.

7. The method according to claim 6, wherein the dispersant is polyethylene glycol 6000.

8. The method according to claim 6, wherein the ball milling is conducted for 40-50 hours.

9. The method according to claim 6, wherein the sintering uses the following heating program: maintaining a heating rate of 100 C./min when a temperature of sintering is below 800 C., controlling the heating rate to 80 C./min when the temperature of sintering is 800-1200 C., and reducing the heating rate to 50 C./min when the temperature of sintering is 1200-1400 C.; with an axial pressure of 30 MPa during the sintering process, and holding for 6 minutes after the temperature reaches 1400 C.

10. The method according to claim 6, wherein the sieving is performed using a 200 mesh screen.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) The accompanying drawings to the specification, which form part of the present invention, are used to provide a further understanding of the present invention, and the illustrative examples of the present invention and the description thereof are used to explain the present invention and are not unduly limiting the present invention.

(2) FIG. 1: (a) SEM image of the oxide layer observed on the repaired surface in Example 2; (b) elemental analysis of the repaired surface for silicon; (c) elemental analysis of the repaired surface for aluminum.

(3) FIG. 2: Cross-sectional SEM image of the Al.sub.2O.sub.3/TiN/TiSi.sub.2 ceramic material prepared in Example 2 of the present invention.

(4) FIG. 3: Morphology of the cracks in the Al.sub.2O.sub.3/TiN/TiSi.sub.2 ceramic material prepared in Example 2 of the present invention.

(5) FIG. 4: Morphology of the surface cracks after healing in the Al.sub.2O.sub.3/TiN/TiSi.sub.2 ceramic material prepared in Example 2 of the present invention.

(6) FIG. 5: XRD phase analysis of the repaired surface of the Al.sub.2O.sub.3/TiN/TiSi.sub.2 ceramic material prepared in Example 2 of the present invention.

(7) FIG. 6: Morphology of surface cracks after healing in the Al.sub.2O.sub.3/TiN ceramic material subjected to heat treatment in Comparative Example 2 of the present invention.

(8) FIG. 7: Cross-sectional SEM image of the Al.sub.2O.sub.3/TiN ceramic material prepared in Comparative Example 2 of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

(9) It should be noted that the following detailed descriptions are all illustrative and intended to provide further clarification of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention belongs.

(10) The present invention will be further described below in conjunction with the following examples.

Example 1

(11) A self-healing ceramic material, consisting of 67.20 vol % Al.sub.2O.sub.3, 16.80 vol % TiN, 15 vol % TiSi.sub.2, 0.5 vol % MgO, and 0.5 vol % Y.sub.2O.sub.3.

(12) A method for preparing the self-healing ceramic material, including the following steps: S1: Considering the density of the materials, Al.sub.2O.sub.3, TiN, and TiSi.sub.2 powders were proportionally weighed, and an appropriate amount of anhydrous ethanol and polyethylene glycol 6000 were added to each ceramic material component, followed by ultrasonic stirring for 30 minutes. Al.sub.2O.sub.3 suspension, TiN suspension, and TiSi.sub.2 suspension were prepared. S2: The aforementioned three suspensions were mixed to obtain a composite phase suspension; then, MgO and Y.sub.2O.sub.3 powders were added proportionally, ultrasonically dispersed, and mechanically stirred for 30 minutes. S3: After the ultrasonication, the obtained mixed liquid was placed into a ball mill jar, and alumina corundum balls weighing five times the mass of the powder were added, along with nitrogen as a protective gas. S4: The ball mill jar was placed in a jar mill and ball milled for 48 hours. The ball-milled ceramic material was then placed in a vacuum drying oven for drying. The powder obtained after drying was sieved through a 200 mesh sieve. The sieved powder was placed into a graphite mold and pre-pressed. S5: The material was sintered in a spark plasma sintering (SPS) furnace. The sintering process of the self-healing ceramic material was adjusted in three stages of heating rates: the heating rate was set at 100 C./min until reaching 800 C.; from 800 C. to 1200 C., the heating rate was adjusted to 80 C./min; and from 1200 C. to 1250 C., the heating rate was further reduced to 50 C./min; with an axial pressure of 30 MPa during the sintering process, and holding for 6 minutes after the temperature reaches 1400 C.

(13) The ceramic material prepared in this example was cut into standard bar samples measuring 3 mm4 mm35 mm, which were then rough ground, fine ground, chamfered, and polished. The mechanical properties were tested, and the results showed that the material had a flexural strength of 685.19 MPa, a hardness of 9.28 GPa and a fracture toughness of 1.75 MPa.Math.m1/2. The performance was relatively good.

Example 2

(14) The composition and sintering process of the self-healing ceramic material were the same as in Example 1, with the following differences: the sintering process of the self-healing ceramic material was adjusted in three stages of heating rates: the heating rate was set at 100 C./min until reaching 800 C.; from 800 C. to 1200 C., the heating rate was adjusted to 80 C./min; and from 1200 C. to 1300 C., the heating rate was further reduced to 50 C./min; with an axial pressure of 30 MPa during the sintering process, and holding for 6 minutes after the temperature reaches 1400 C.

(15) The Al.sub.2O.sub.3/TiN/TiSi.sub.2 ceramic material prepared in this example was cut into standard bar samples measuring 3 mm4 mm35 mm, which were then rough ground, fine ground, chamfered, and polished. The mechanical properties were tested, and the results showed that the material had a flexural strength of 719.31 MPa, a hardness of 16.55 GPa and a fracture toughness of 4.73 MPa.Math.m1/2. The overall performance was the best.

(16) Using a Vickers hardness tester, a pre-crack was created on the smooth ceramic surface under a load of 196 N with a dwell time of 15 seconds, as shown in FIG. 3.

(17) The cracked samples were subjected to different heat treatments in a high-temperature air furnace. When the heat treatment temperature was 600 C. with a hold time of 60 minutes, the degree of crack repair was low. This was due to the formation of an oxide layer by TiSi.sub.2 on the repair surface, which hindered the interaction between the repair phase and O.sub.2, reducing the effectiveness of the repair, as shown in FIG. 1. When the heat treatment temperature was 700 C. with a hold time of 60 minutes, the crack repair was more effective. When the heat treatment temperature was 800 C. with a hold time of 60 minutes, the cracks were almost completely repaired, and the surface porosity was low, as shown in FIG. 4.

(18) XRD phase analysis of the surface of the Al.sub.2O.sub.3/TiN/TiSi.sub.2 ceramic material was shown in FIG. 5. Observing FIG. 5, distinct peaks of Al.sub.2O.sub.3, TiN, TiSi.sub.2, and TiO.sub.2 were evident, with no other impurity peaks detected, indicating that no impurities were introduced during the preparation and sintering processes, and no reactions occurred between the phases. No peaks of MgO, Y.sub.2O.sub.3, and SiO.sub.2 were detected, suggesting that the content of these materials was low. The presence of TiO.sub.2 indicated the oxidation of TiN to form the repair phase TiO.sub.2, which filled the cracks.

(19) By observing and comparing FIG. 2 and FIG. 7, it was found that TiSi.sub.2 reduced the porosity during the sintering process. Similarly, comparing FIG. 4 and FIG. 6 revealed that TiSi.sub.2 reduced the porosity on the repair surface.

Example 3

(20) The composition and sintering process of the self-healing ceramic material were the same as in Example 1, with the following differences:

(21) The sintering process of the self-healing ceramic material was adjusted in three stages of heating rates: the heating rate was set at 100 C./min until reaching 800 C.; from 800 C. to 1200 C., the heating rate was adjusted to 80 C./min; and from 1200 C. to 1350 C., the heating rate was further reduced to 50 C./min; with an axial pressure of 30 MPa during the sintering process, and holding for 6 minutes after the temperature reaches 1400 C. The cross-sectional SEM image of the prepared Al.sub.2O.sub.3/TiN/TiSi.sub.2 ceramic material was shown in FIG. 2.

(22) The ceramic material prepared in this example was cut into standard bar samples measuring 3 mm4 mm35 mm, which were then rough ground, fine ground, chamfered, and polished. The mechanical properties were tested, and the results showed that the material had a flexural strength of 709.70 MPa, a hardness of 15.74 GPa and a fracture toughness of 4.34 MPa.Math.m1/2.

(23) In Comparative Examples 1-3, the composition of the self-healing ceramic material consisted of Al.sub.2O.sub.3 as the matrix, TiN as the repair agent, and MgO and Y.sub.2O.sub.3 as sintering aids. The volume percentages of each component were 79.20 vol % for Al.sub.2O.sub.3, 19.80 vol % for TiN, 0.5 vol % for MgO, and 0.5 vol % for Y.sub.2O.sub.3.

(24) The average particle sizes of Al.sub.2O.sub.3 and TiN powders were 0.5-1 m, the average particle size of Y.sub.2O.sub.3 powder was 1-3 m, and the average particle size of MgO powder was 0.5 m.

(25) Al.sub.2O.sub.3 and TiN powders were weighed proportionally, and each component of the ceramic materials was mixed with an appropriate amount of anhydrous ethanol and polyethylene glycol dispersant, followed by ultrasonic stirring for 30 minutes. Al.sub.2O.sub.3 suspension and TiN suspension were prepared.

(26) The aforementioned suspensions were mixed to obtain a composite phase suspension. MgO and Y.sub.2O.sub.3 powders were then added proportionally, followed by ultrasonic dispersion and mechanical stirring for 30 minutes. After ultrasonication, the mixture was transferred into a ball mill jar, and alumina corundum balls weighing five times the mass of the powder were added, along with nitrogen as a protective gas. The ball mill jar was placed in a jar mill and ball milled for 48 hours.

(27) Afterwards, the ball-milled ceramic material was placed in a vacuum drying oven and dried for 24 hours. The powder obtained after drying was sieved through a 200 mesh sieve. The sieved powder was placed into a graphite mold and pre-pressed. The material was sintered in a spark plasma sintering (SPS) furnace.

Comparative Example 1

(28) The sintering process of the self-healing ceramic material was adjusted in three stages of heating rates: the heating rate was set at 100 C./min until reaching 800 C.; from 800 C. to 1200 C., the heating rate was adjusted to 80 C./min; and from 1200 C. to 1450 C., the heating rate was further reduced to 50 C./min; with an axial pressure of 30 MPa during the sintering process, and holding for 6 minutes after the temperature reaches 1400 C.

(29) The ceramic material prepared in this example was cut into standard bar samples measuring 3 mm4 mm35 mm, which were then rough ground, fine ground, chamfered, and polished. The mechanical properties were tested, and the results showed that the material had a flexural strength of 530.30 MPa, a hardness of 18.35 GPa and a fracture toughness of 4.29 MPa.Math.m1/2. The overall performance was relatively low.

Comparative Example 2

(30) The sintering process of the self-healing ceramic material was adjusted in three stages of heating rates: the heating rate was set at 100 C./min until reaching 800 C.; from 800 C. to 1200 C., the heating rate was adjusted to 80 C./min; and from 1200 C. to 1475 C., the heating rate was further reduced to 50 C./min; with an axial pressure of 30 MPa during the sintering process, and holding for 6 minutes after the temperature reaches 1400 C.

(31) The cross-sectional SEM image of the prepared Al.sub.2O.sub.3/TiN ceramic material was shown in FIG. 7. The grains are uniform without any abnormal growth, and there are few pores, indicating good sintering results.

(32) The ceramic material prepared in this example was cut into standard bar samples measuring 3 mm4 mm35 mm, which were then rough ground, fine ground, chamfered, and polished. The mechanical properties were tested, and the results showed that the material had a flexural strength of 574.51 MPa, a hardness of 18.74 GPa and a fracture toughness of 4.51 MPa.Math.m1/2. The overall performance was good. Using a Vickers hardness tester, a pre-crack was created on the smooth ceramic surface under a load of 196 N with a dwell time of 15 seconds.

(33) The cracked samples were subjected to different heat treatments in a high-temperature air furnace. When the heat treatment temperature was 600 C. with a hold time of 60 minutes, the degree of crack repair was low. When the heat treatment temperature was 700 C. with a hold time of 60 minutes, the crack repair was more effective. When the heat treatment temperature was 800 C. with a hold time of 60 minutes, the cracks were almost completely repaired, but the surface porosity was high, as shown in FIG. 6.

Comparative Example 3

(34) The sintering process of the self-healing ceramic material was adjusted in three stages of heating rates: the heating rate was set at 100 C./min until reaching 800 C.; from 800 C. to 1200 C., the heating rate was adjusted to 80 C./min; and from 1200 C. to 1500 C., the heating rate was further reduced to 50 C./min; with an axial pressure of 30 MPa during the sintering process, and holding for 6 minutes after the temperature reaches 1400 C.

(35) The ceramic material prepared in this example was cut into standard bar samples measuring 3 mm4 mm35 mm, which were then rough ground, fine ground, chamfered, and polished. The mechanical properties were tested, and the results showed that the material had a flexural strength of 537.50 MPa, a hardness of 18.40 GPa and a fracture toughness of 4.37 MPa.Math.m1/2. The overall performance was decreased.

(36) The above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, various changes and modifications can be made to the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principles of the present invention should be included within the scope of the present invention's protection.