Toughened ceramic material

Abstract

A toughened ceramic material includes at least one boride and a refractory metal, or at least two borides, one carbide at least, and a refractory metal. The toughened ceramic material is by means of heating and smelting the above materials. During the process of preparing the toughened ceramic material by heating and smelting, substantially all the refractory metal reacts with the boride and/or the carbide to form a toughened ceramic material with a high toughness and substantially without metallic cemented phase.

Claims

1. A toughened ceramic material, comprising two borides, at least one carbide, and a refractory metal; wherein the said two borides are TiB.sub.2 and ZrB.sub.2; the said carbide is from the group of SiC, B.sub.4C, TiC, NbC, TaC and WC; and the said refractory metal is tungsten, with a toughened ceramic material being prepared by smelting the two borides, the at least one carbide and the refractory metal together; and when the two borides, the at least one carbide and the refractory metal are heated and smelted, substantially all the refractory metal reacts with the two borides and/or the at least one carbide to form a pure ceramic structure without any metallic cemented phase.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a flow chart of the process for preparing the toughened ceramic material of the disclosure;

(2) FIG. 2 is a schematic view of the XRD analysis of the toughened ceramic material according to the first embodiment of the disclosure;

(3) FIG. 3 is a schematic view of the XRD analysis of the toughened ceramic material according to the second embodiment of the disclosure;

(4) FIG. 4 is a schematic view of the XRD analysis of the toughened ceramic material according to the third embodiment of the disclosure;

(5) FIG. 5 is a schematic view of the XRD analysis of the toughened ceramic material according to the fourth embodiment of the disclosure;

(6) FIG. 6 is a schematic view of the XRD analysis of the toughened ceramic material according to the fifth embodiment of the disclosure;

(7) FIG. 7 is a schematic view of the XRD analysis of the toughened ceramic material according to the sixth embodiment of the disclosure;

(8) FIG. 8 is a schematic view of the XRD analysis of the toughened ceramic material according to the seventh embodiment of the disclosure;

(9) FIG. 9 is a schematic view of the XRD analysis of the toughened ceramic material according to the eighth embodiment of the disclosure;

(10) FIG. 10 is a schematic view of the XRD analysis of the toughened ceramic material according to the ninth embodiment of the disclosure;

(11) FIG. 11 is a schematic view of the XRD analysis of the toughened ceramic material according to the tenth embodiment of the disclosure;

(12) FIG. 12 is a schematic view of the XRD analysis of the toughened ceramic material according to the eleventh embodiment of the disclosure;

(13) FIG. 13 is a schematic view of the XRD analysis of the toughened ceramic material according to the twelfth embodiment of the disclosure;

(14) FIG. 14 is a schematic view of the XRD analysis of the toughened ceramic material according to the thirteenth embodiment of the disclosure; and

(15) FIG. 15 is a schematic view of the XRD analysis of the toughened ceramic material according to the fourteenth embodiment of the disclosure.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(16) The technical solutions, features and effects of the disclosure are clearly the description of disclosed embodiments with reference to the drawings.

(17) Referring to FIG. 1, the preparation is as the following:

(18) (1) At least one boride and a refractory metal (or at least two borides, one or more carbide, and a refractory metal) are mixed properly, and then the mixed could be disposed in a groove of a water-cooled copper mold of a vacuum arc the smelting furnace (101);

(19) (2) After the pressure of the vacuum arc smelting furnace reduces to vacuum (the pressure of the furnace is 2.410.sup.2 torr), pure argon (Ar) incorporates until the pressure elevates to about 8.0 torr, and then the pressure reduces to vacuum again (reduced to 2.410.sup.2 ton). The process of incorporating Ar and then reducing the pressure is purge. The above process repeats for several times; and then argon incorporates until the pressure is back to about 8.0 torr and smelting is performing (102); and

(20) (3) After the performance of smelting and the specimen completely cools, the specimen repeats turning upside down and smelting again. This process repeats for several times to ensure the uniformity of the specimen. As the above was done and the specimen is completely cooled one more time, the pressure of the furnace is elevated to 1 atm; and the formed specimen of the toughened cermet material is obtained (103).

(21) The composition of the first embodiment (B1B2+Ta) is (TiB.sub.2).sub.0.3(ZrB.sub.2).sub.0.3Ta.sub.0.4, and the XRD analysis is shown in FIG. 2, which is indicative of the phase composition of MB, MB.sub.2 and M.sub.2B with the peaks, without significant signals of cemented phase Ta solid solution. In other words, the toughened ceramic material disclosed in the first embodiment is substantially a pure ceramic. The fraction of M.sub.2B phase is high, such that its mechanical properties are hard and brittle, the hardness is 184274 HV, and the fracture toughness is 6.440.99 MPa m.sup.1/2.

(22) The composition of the second embodiment (SB4) is (NbB.sub.2).sub.0.6W.sub.0.4, and the corresponding XRD analysis is shown in FIG. 3, which shows three phases, i.e. M.sub.2B, MB and MB.sub.2 with three peak patterns, respectively. Since almost all the W in the second embodiment reacts with B and forms MB or M.sub.2B, the formed pure ceramic structure is without the cemented phase of the refractory metal. In this embodiment the hardness is 194456 HV and the toughness is 7.720.72 MPa m.sup.1/2.

(23) The composition of the third embodiment (B3B5) is [(HfB.sub.2)(TaB.sub.2)].sub.0.6W.sub.0.4, and the corresponding XRD analysis is shown in FIG. 4. Three peak patterns in FIG. 4 correspond to three phases, i.e. M.sub.2B, MB and MB.sub.2, respectively. In the third embodiment, the hardness is 191193 HV, and the fracture toughness is 5.120.34 MPa m.sup.1/2.

(24) The composition of the fourth embodiment (B3B6) is [(HfB.sub.2)(W.sub.2B.sub.5).sub.0.5].sub.0.6W.sub.0.4, and the corresponding XRD analysis is shown in FIG. 5. Two peak patterns correspond to two phases of MB and MB.sub.2, respectively. The fourth embodiment has hardness of 184187 HV, and its fracture toughness is 5.660.34 MPa m.sup.1/2.

(25) The composition of the fifth embodiment (B4B5) is [(NbB.sub.2)(TaB.sub.2)].sub.0.6W.sub.0.4, and the corresponding XRD analysis is shown in FIG. 6. Two peak patterns in FIG. 6 show that there are two phases of MB and MB.sub.2. The fifth embodiment shows virtually nowhere the cemented phase and merely a pure ceramic structure with the hardness of 199681 HV and the fracture toughness of 6.060.24 MPa m.sup.1/2.

(26) The composition of the sixth embodiment (B4B6) is [(NbB.sub.2)(W.sub.2B.sub.5)].sub.0.6W.sub.0.4, and the corresponding XRD analysis is shown in FIG. 7. FIG. 7 shows three peak patterns indicative of three phases of M.sub.2B, MB and MB.sub.2, respectively. The hardness is 216528 HV, and the fracture toughness is 7.880.17 MPa m.sup.1/2.

(27) [(TiB.sub.2)(ZrB.sub.2)(HfB.sub.2)(NbB.sub.2)(TaB.sub.2)(W.sub.2B.sub.5).sub.0.5].sub.0.6W.sub.0.4 is the composition of the seventh embodiment ((6B)6W4) and the corresponding XRD analysis is shown in FIG. 8 indicates there are two phases of MB and MB.sub.2. The seventh embodiment has the hardness of 184187 HV, and the fracture toughness of 5.060.41 MPa m.sup.1/2.

(28) The composition of the eighth embodiment (B3B4+W) is [(HfB.sub.2)(NbB.sub.2)].sub.0.4W.sub.0.6, and the corresponding XRD analysis is shown in FIG. 9. Three peak patterns correspond to three phases of M.sub.2B, MB and MB.sub.2, respectively. Similarly, in the eighth embodiment, metallic cemented phase substantially appears nowhere once after most of W reacts and forms the hard and brittle phase while part of W forms MB. For the eighth embodiment the hardness is 174248 HV, and the fracture toughness is 6.880.44 MPa m.sup.1/2.

(29) The composition of the ninth embodiment (B3B5+W) is [(HfB.sub.2)(TaB.sub.2)].sub.0.4W.sub.0.6, and the corresponding XRD analysis is shown in FIG. 10. Two patterns of peaks correspond to two phases of W.sub.2B and MB, respectively. In the ninth embodiment, there are no significant cemented phase residues, the hardness is 186366 HV, and the fracture toughness is 6.560.44 MPa m.sup.1/2.

(30) [(TiB.sub.2)(ZrB.sub.2)(HfB.sub.2)(NbB.sub.2)(TaB.sub.2)].sub.0.5W.sub.0.5 is the composition of the tenth embodiment ((5B)5W5), and the corresponding XRD analysis is shown in FIG. 11 where three patterns of peaks correspond to three phases of W.sub.2B, MB and MB.sub.2, respectively. In the tenth embodiment, the hardness is 207656 HV, and the fracture toughness is 5.990.50 MPa m.sup.1/2.

(31) The eleventh embodiment ((4B)4W6) has [(TiB.sub.2)(ZrB.sub.2)(NbB.sub.2)(TaB.sub.2)].sub.0.4W.sub.0.6 in composition and the corresponding XRD analysis is shown in FIG. 12 in which three patterns of peaks correspond to three phases of W.sub.2B, MB and MB.sub.2, respectively. The mechanical properties of the eleventh embodiment are similar to those of (5B)5W5, the hardness is 204547 HV, and the fracture toughness is 5.770.37 MPa m.sup.1/2.

(32) The twelfth embodiment (+SiC) has [(TiB.sub.2)(ZrB.sub.2)(SiC)].sub.0.6W.sub.0.4 in composition and the corresponding XRD analysis is shown in FIG. 13 in which four patterns of peaks correspond to four phases of SiC, MSi.sub.2, MB and MB.sub.2, respectively. The specimen shows a hardness of 189865 HV, and the fracture toughness of 5.890.53 MPa m.sup.1/2.

(33) The thirteenth embodiment (+B.sub.4C) is [(TiB.sub.2)(ZrB.sub.2)(B.sub.4C)].sub.0.6W.sub.0.4, and the corresponding XRD analysis is shown in FIG. 14 where four peak patterns simply correspond to three phases of MC, MB and MB.sub.2, respectively. In the embodiment, there are numerous coarse MB.sub.2 phase and a small amount of MB phase present, because all the cemented phase of W reacts and forms the ceramic-like boride such that no metallic solid solutions appear.

(34) [(TiC)(NbC)(TaC)(WC)(TiB.sub.2)(ZrB.sub.2)].sub.0.6W.sub.0.4 is the fourteenth embodiment (+TZ), and its corresponding XRD analysis is shown in FIG. 15 where three peak patterns correspond to three phases of MC, MB and M.sub.2B, respectively. In this embodiment, no cemented phases, W solid solutions, appear in microstructure, and there are no layered structures as in the original NbTa series. There are only numerous dispersed particles of M.sub.2B accompanied with MC therein. The hardness is 220383 HV, and the fracture toughness is 6.030.25 MPa m.sup.1/2.

(35) In the above embodiments, there are no metallic cemented phase residues in microstructure because there are many boron atoms in the composition. In addition, metallic cemented phase is reactive with boron, rendering the cemented phase W solid solution difficult to be present, and therefore resulting in the structure similar to pure ceramics.

(36) As compared to traditional technologies, the toughened ceramic material of the disclosure has the following advantages:

(37) 1. According to the disclosure, the material is prepared by smelting. During the preparation of the toughened ceramic material, if the refractory metal can only react with the boride or/and the carbide at different planned composition ratios, metallic cemented phase appear virtually nowhere resulting in ae pure ceramic structure with a high toughness.

(38) 2. According to the disclosure, the toughened ceramic is a smelted material, and a higher density results in a better toughness. Thus, the hardness and the toughness of the prepared material improve, the hardness stability under high temperatures is better. Therefore, it is suitable for general industry.

(39) Note that the specifications relating to the above embodiments should be construed as exemplary rather than as limitative of the present disclosure. The equivalent variations and modifications on the structures or the process by reference to the specification and the drawings of the disclosure, or application to the other relevant technology fields directly or indirectly should be construed similarly as falling within the protection scope of the disclosure.