PREPARATION METHOD FOR ALUMINA/TITANIUM SILICON CARBIDE COMPOSITE MATERIAL

Abstract

An alumina/titanium silicon carbide composite material is prepared by making titanium aluminum carbide (Ti.sub.3AlC.sub.2) in uniform contact with silicon monoxide (SiO), and carrying out vacuum sintering. The composite material is obtained through mutual diffusion of aluminum and silicon and has high compactness and stable performance. In the composite material, the alumina is generated by means of a reaction between the titanium aluminum carbide and the silicon monoxide, and can be uniformly wrapped around surfaces of titanium silicon carbide crystals to form a relatively compact oxide film, such that substance exchange between a matrix and the outside is hindered, and overall antioxidation of the composite material is improved. Toughness of the composite material is enhanced by means of the titanium silicon carbide. The prepared composite material has relatively high purity, relatively low sintering temperature, and relatively high bending strength. The process is simple and convenient for industrial production.

Claims

1. A preparation method for an alumina/titanium silicon carbide composite material, wherein the alumina/titanium silicon carbide composite material is prepared with a titanium aluminum carbide Ti.sub.3AlC.sub.2 powder and a silicon monoxide SiO powder as a raw material; and wherein the method comprises the following steps: (1) mixing the titanium aluminum carbide Ti.sub.3AlC.sub.2 powder and the silicon monoxide SiO powder uniformly to obtain a mixture, wherein a molar ratio of titanium aluminum carbide to silicon monoxide is 1: 0.5-1.5; and (2) sintering the mixture under conditions of a heat preservation and a pressurization, carrying out a cooling along with a furnace after the heat preservation and the pressurization, and turning off a vacuum system after the cooling to obtain a pancake-shaped alumina/titanium silicon carbide composite material, wherein sintering under the heat preservation comprises: carrying out a first heating to 1200° C. at a first heating rate of 1° C.-10° C. first, then carrying out a second heating to 1250° C.-1350° C. at a second heating rate of 5° C./min-20° C./min, and carrying out the heat preservation for 1.5 h - 3 h; and a sintering pressure is 25 MPa-35 MPa.

2. The preparation method according to claim 1, wherein in the step (1), the titanium aluminum carbide has a grain size of 3 μm-15 μm, the silicon monoxide has a grain size of 0.5 μm-5 μm, and a purity is 99.9%.

3. The preparation method according to claim 1, wherein in the step (1), the mixture is mixed through a ball milling method.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] FIG. 1 is an X-ray diffraction pattern of a titanium silicon carbide/alumina composite material prepared by means of sintering through a mixing method in the present disclosure.

[0019] FIG. 2 is a microscopic image of a titanium silicon carbide/alumina composite material prepared by means of sintering through a mixing method in the present disclosure.

[0020] FIGS. 3A-3F are elemental analysis diagrams of a titanium silicon carbide/alumina composite material prepared by means of sintering through a mixing method in the present disclosure.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0021] The present disclosure will be further illustrated below by means of examples, and it needs to be emphasized that the following description is only used for explaining the present disclosure, and is not intended to limit the contents thereof.

Embodiment 1

[0022] (1) 44.22 g of titanium aluminum carbide (Ti.sub.3AlC.sub.2) having a grain size of about 10 μm and 10.01 g of silicon monoxide (SiO) having a grain size of 1 μm-5 μm are added into a steel tank of a planetary ball mill to form totally about 54.23 g of mixture, a molar ratio of titanium aluminum carbide to silicon monoxide being about 1:1, the mixture is stirred with a glass rod so as to be more uniform, and then, 108.81 g of steel balls are put in, a mass ratio of the mixture to the balls being about 1:2.

[0023] (2) The steel tank of the planetary ball mill filled with the mixture in the step (1) is put into the planetary ball mill, a ball milling speed is set as 70 r/min, ball milling pauses for 10 min after being carried out 30 min each time, ball milling time is totally 2 h, and pause time is 30 min. After ball milling is finished, the mixture is taken out.

[0024] (3) The mixture obtained in the step (2) is loaded, in a structure of “lower pressure head-gasket-carbon paper-mixture-carbon paper-gasket-upper pressure head”, into a hollow cylindrical graphite mold having a diameter of about 45 mm, the mold is put into a vacuum hot-pressing furnace, a vacuum system is turned on for vacuumizing, heating is carried out to 1200° C. at a heating rate of 10° C./min, then heating is carried to 1300° C. at a heating rate of 5° C./min, heat preservation is carried out at 1300° C. for 120 min, a sintering pressure is 30 Mpa, pressurization is started before heating is carried out to 1300° C., and a pressure is maintained for 120 min. After heat preservation and pressurization are finished, cooling is carried out along with a furnace, and when cooling is carried out to 200° C., the vacuum system is turned off to obtain a pancake-shaped alumina/titanium silicon carbide composite material.

[0025] (4) A surface of the pancake-shaped alumina/titanium silicon carbide composite material in the step (3) is polished by means of sand paper and a polishing machine to remove the carbon paper combined with the surface of the sample, so as to obtain a usable sample.

Embodiment 2

[0026] (1) 43.92 g of titanium aluminum carbide (Ti.sub.3AlC.sub.2) having a grain size of about 8 μm and 9.99 g of silicon monoxide (SiO) having a grain size of 1 μm-5 μm are added into a steel tank of a planetary ball mill to form totally about 53.91 g of mixture, a molar ratio of titanium aluminum carbide to silicon monoxide being about 1:1, and the mixture is stirred with a glass rod so as to be more uniform. Then, 107.54 g of steel balls are put in, a mass ratio of the mixture to the balls being about 1:2.

[0027] (2) The steel tank of the planetary ball mill filled with the mixture in the step (1) is put into the planetary ball mill, a ball milling speed is set as 70 r/min, ball milling pauses for 10 min after being carried out 30 min each time, ball milling time is totally 2 h, and pause time is 30 min. After ball milling is finished, the mixture is taken out.

[0028] (3) The mixture obtained in the step (2) is loaded, in a structure of “lower pressure head-gasket-carbon paper-mixture-carbon paper-gasket-upper pressure head”, into a hollow cylindrical graphite mold having a diameter of about 45 mm, the mold is put into a vacuum hot-pressing furnace, a vacuum system is turned on for vacuumizing, heating is carried out to 1200° C. at a heating rate of 8° C./min, then heating is carried to 1340° C. at a heating rate of 5° C./min, heat preservation is carried out at 1340° C. for 120 min, a sintering pressure is 30 Mpa, pressurization is started before heating is carried out to 1340° C., and a pressure is maintained for 120 min. After heat preservation and pressurization are finished, cooling is carried out along with a furnace, and when cooling is carried out to 200° C., the vacuum system is turned off to obtain a pancake-shaped alumina/titanium silicon carbide composite material.

[0029] (4) A surface of the pancake-shaped alumina/titanium silicon carbide composite material in the step (3) is polished by means of sand paper and a polishing machine to remove the carbon paper combined with the surface of the sample, so as to obtain a usable sample.

Embodiment 3

[0030] (1) 44.13 g of titanium aluminum carbide (Ti.sub.3AlC.sub.2) having a grain size of about 10 μm and 10.82 g of silicon monoxide (SiO) having a grain size of 1 μm-5 μm are added into a steel tank of a planetary ball mill to form totally about 54.95 g of mixture, a molar ratio of titanium aluminum carbide to silicon monoxide being about 1:1, and the mixture is stirred with a glass rod so as to be more uniform. Then, 110.69 g of steel balls are put in, a mass ratio of the mixture to the balls being about 1:2.

[0031] (2) The steel tank of the planetary ball mill filled with the mixture in the step (1) is put into the planetary ball mill, a ball milling speed is set as 70 r/min, ball milling pauses for 10 min after being carried out 30 min each time, ball milling time is totally 2 h, and pause time is 30 min. After ball milling is finished, the mixture is taken out.

[0032] (3) The mixture obtained in the step (2) is loaded, in a structure of “lower pressure head-gasket-carbon paper-mixture-carbon paper-gasket-upper pressure head”, into a hollow cylindrical graphite mold having a diameter of about 45 mm, the mold is put into a vacuum hot-pressing furnace, a vacuum system is turned on for vacuumizing, heating is carried out to 1200° C. at a heating rate of 12° C./min, then heating is carried to 1280° C. at a heating rate of 5° C./min, heat preservation is carried out at 1280° C. for 120 min, a sintering pressure is 35 Mpa, pressurization is started before heating is carried out to 1280° C., and a pressure is maintained for 120 min. After heat preservation and pressurization are finished, cooling is carried out along with a furnace, and when cooling is carried out to 200° C., the vacuum system is turned off to obtain a pancake-shaped alumina/titanium silicon carbide composite material.

[0033] (4) A surface of the pancake-shaped alumina/titanium silicon carbide composite material in the step (3) is polished by means of sand paper and a polishing machine to remove the carbon paper combined with the surface of the sample, so as to obtain a usable sample.

Embodiment 4

[0034] (1) 44.03 g of titanium aluminum carbide (Ti.sub.3AlC.sub.2) having a grain size of about 12 μm and 10.55 g of silicon monoxide (SiO) having a grain size of 0.5-3 μm are added into a steel tank of a planetary ball mill to form totally about 54.58 g of mixture, a molar ratio of titanium aluminum carbide to silicon monoxide being about 1:1, and the mixture is stirred with a glass rod so as to be more uniform. Then, 109.9 g of steel balls are put in, a mass ratio of the mixture to the balls being about 1:2.

[0035] (2) The steel tank of the planetary ball mill filled with the mixture in the step (1) is put into the planetary ball mill, a ball milling speed is set as 70 r/min, ball milling pauses for 10 min after being carried out 30 min each time, ball milling time is totally 2 h, and pause time is 30 min. After ball milling is finished, the mixture is taken out.

[0036] (3) The mixture obtained in the step (2) is loaded, in a structure of “lower pressure head-gasket-carbon paper-mixture-carbon paper-gasket-upper pressure head”, into a hollow cylindrical graphite mold having a diameter of about 45 mm, the mold is put into a vacuum hot-pressing furnace, a vacuum system is turned on for vacuumizing, heating is carried out to 1200° C. at a heating rate of 1° C./min, then heating is carried to 1280° C. at a heating rate of 5° C./min, heat preservation is carried out at 1280° C. for 100 min, a sintering pressure is 30 Mpa, pressurization is started before heating is carried out to 1280° C., and a pressure is maintained for 100 min. After heat preservation and pressurization are finished, cooling is carried out along with a furnace, and when cooling is carried out to 200° C., the vacuum system is turned off to obtain a pancake-shaped alumina/titanium silicon carbide composite material.

[0037] (4) A surface of the pancake-shaped alumina/titanium silicon carbide composite material in the step (3) is polished by means of sand paper and a polishing machine to remove the carbon paper combined with the surface of the sample, so as to obtain a usable sample.

Effect Embodiments

[0038] (1) The composite material prepared in embodiments 1-4 is subjected to a bending strength test, and specific test results are shown in Table 1.

[0039] The bending strength test is used for testing bending strength of a sample through a three-point bending method. Firstly, a sintered ceramic wafer is put on a grinding machine for coarse grinding, so as to remove graphite paper and impurities covering a surface of a sample, and the surface of the sample is roughly ground to be flat; then the roughly ground sample is polished; and finally the polished sample is cut into required sample strips by a wire cutting machine. Surfaces of the sample strips are smooth without visible defects, and each sample strip has a length of 36 mm, a width of 4 mm, and a height of 3 mm. An actual span in the sample test is 30 mm. The bending strength of the prepared sample is tested by an electronic universal material testing machine, and a pressing speed of an upper pressure head of the testing machine is 0.5 mm/min. A load P is recorded, and the bending strength is computed. Each sample is prepared into three sample strips to be tested three times, and finally a mean value is computed.

[0040] The bending strength is computed according to bending strength formulas of the following materials:

[00001]${\sigma }_f=\frac{3\mathrm{PL}}{2{\mathrm{bh}}^2}$

[0041] σ.sub.f—bending strength (Mpa);

[0042] P—fracture load (N);

[0043] L—fulcrum span (mm);

[0044] b, h—width and thickness of a sample (mm).

TABLE-US-00001 TABLE 1 Bending Strength (Mpa) Embodiment 1 Embodiment 2 Embodiment 3 Embodiment 4 Mean value 349.5 347.9 371.6 386.3

[0045] (2) An X-ray diffraction pattern of a titanium silicon carbide/alumina composite material prepared by mixing, by means of ball milling, and sintering titanium aluminum carbide/silicon monoxide prepared in the present disclosure is shown in FIG. 1, and a microscopic image and elemental analysis are shown in FIGS. 2 and 3A-3F.

[0046] FIG. 1 is an X-ray diffraction pattern of a titanium silicon carbide/alumina composite material prepared by mixing, by means of ball milling, and sintering titanium aluminum carbide/silicon monoxide. X-ray peaks reveal a Ti.sub.3SiC.sub.2 phase (*), a Al.sub.2O.sub.3 phase (.diamond-solid.) and an amorphous phase (Δ) in the composite material. The amorphous phase corresponds to a protrusion at a left side of FIG. 1. The Ti.sub.3SiC.sub.2 phase and the Al.sub.2O.sub.3 phase have clear XRD (X-ray diffraction) peaks.

[0047] FIG. 2 is a microscopic image shown in a scanning electron microscope of a fracture surface generated in a bending strength test of a titanium silicon carbide/alumina composite material prepared by mixing, by means of ball milling, and sintering titanium aluminum carbide/silicon monoxide. An SEM (scanning electron microscope) micrograph of the fracture surface generated in a bending strength test contains layered crystal structures, each of the layered crystal structure having a length of about 10 μm, and crystal structures in other shapes around the layered crystal structures. The silicon monoxide phase may be removed during fracture test and ultrasonic treatment.

[0048] FIGS. 3A-3F are element distribution diagrams corresponding to FIG. 2. Distribution of Ti—Si—C is consistent with distribution of Al—O, and carbon from a decomposed Ti.sub.3—C.sub.2 layer is found. Thus, it is determined that in the SEM micrograph, a plurality of layers of Ti.sub.3SiC.sub.2 is tightly surrounded by Al.sub.2O.sub.3 (FIG. 2). There is no obvious Al signals in broken MAX grains, which implies that SiO may convert Ti.sub.3AlC.sub.2 having a grain size of 10 μm into layered Ti.sub.3SiC.sub.2.