KR101860477B1 - Composition used for manufacturing SiC-Zr2CN composites and method for manufacturing SiC-Zr2CN composites using the same - Google Patents

Abstract

The present invention relates to a composition for manufacturing a silicon carbide-zirconium carbonitride composite material, and a method for manufacturing a silicon carbide-zirconium carbonitride composite material using the same. According to an embodiment of the present invention, the composition for manufacturing a silicon carbide-zirconium carbonitride composite material using the same comprises 41.0-91.0 wt% of β-silicon carbide (β-SiC), 8.0-55.0 wt% of zirconium nitride (ZrN), and 1.0-4.0 wt% of a sintering additive. According to the present invention, the composition for manufacturing a silicon carbide-zirconium carbonitride composite material, and the method for a manufacturing silicon carbide-zirconium carbonitride composite material using the same can manufacture an electrical conductivity ceramic composite material having high electrical conductivity.

Description

[0001] The present invention relates to a composition for producing a silicon carbide-zirconium carbonitride composite material and a process for producing a silicon carbide-zirconium carbonitride composite material using the same,

The present invention relates to a composition for preparing a ceramic composite material, a method for manufacturing a ceramic composite material using the same, and a ceramic composite material produced thereby.

Ceramics are used to manufacture products in various industrial fields due to excellent physical and mechanical properties, which is a general term for non-metallic inorganic materials made by applying heat.

In recent years, there has been a great deal of research on structural ceramics having high strength as the demands of industry for lightweight, high strength, or high heat resistant materials are increasing. Materials for such structural ceramics include silicon carbide (SiC) Alumina (Al ₂ O ₃ ), zirconia (MgO stb. ZrO ₂ / Y ₂ O ₃ stb. ZrO ₂ ), boron nitride (BN) or silicon nitride (Si ₃ N ₄ ) are widely used.

Among them, silicon carbide (SiC) is used for manufacturing semiconductor process parts and chemical resistant machine parts because it has various advantages such as high strength and hardness, excellent high temperature property, radiation resistance characteristic and plasma plasma corrosion characteristic.

Zirconium nitride (ZrN), on the other hand, has a wide range of structural and functional properties such as high melting point, high electrical conductivity, excellent chemical stability, low neutron capture ability, and corrosion resistance to molten iron and steel. It is an important ceramics material having use.

However, despite the fact that silicon carbide and zirconium nitride are attractive materials having different merits as described above, a technology for a binary composite in which silicon carbide and zirconium nitride are combined as materials having respective merits to date Is not known.

Korean Patent Publication No. 10-2015-0114942 (Publication date: October 13, 2015) Korean Patent Publication No. 10-2015-0135690 (Publication date: December 3, 2015). Korean Patent Publication No. 10-2014-0106777 (Publication date: 2014.09.04.) Korean Patent Laid-Open No. 10-1397153 (Registered on May 13, 2014). Korean Patent Laid-Open No. 10-2014-0073091 (Publication date: June 16, 2014).

Disclosure of the Invention The present invention has been conceived to solve the problems of the prior art as described above, and provides a composition for the production of a novel binary composite in which silicon carbide and zirconium nitride are combined, and a method for producing a composite using the composite .

In order to accomplish the above-mentioned technical object, the present invention provides a method of manufacturing a silicon carbide semiconductor device, 8.0 to 55.0 wt% zirconium nitride (ZrN); Zirconium carbonitride (SiC-Zr ₂ CN) composite material, which comprises a sintering additive and a sintering additive in an amount of 1.0 to 4.0% by weight.

Also, the present invention provides a composition for producing a silicon carbide-zirconium carbonitride (SiC-Zr ₂ CN) composite material, wherein the β-silicon carbide is a micron or a sub-micron powder.

The sintering additive may include silicon carbide-zirconium carbonitride (SiC-zirconium carbonitride) in a molar ratio of yttrium oxide (Y ₂ O ₃ ) and scandium oxide (III) (Sc ₂ O ₃ ) Zr ₂ CN) composite material.

In another aspect of the present invention, the present invention provides a process for producing a silicon carbide powder, comprising the steps of: (a) blending 41.0 to 91.0% by weight of? -Silicon carbide (? -SiC) powder; 8.0 to 55.0% by weight of zirconium nitride (ZrN) powder; And 1.0 to 4.0% by weight of a sintering additive powder; And (b) sintering the mixed powder obtained in the step (a) under a nitrogen (N ₂ ) atmosphere to produce a composite material of silicon carbide-zirconium carbonitride (SiC-Zr ₂ CN) A method for producing a carbonitride (SiC-Zr ₂ CN) composite material is provided.

(SiC-Zr ₂ CN) composite material in the step (b) is characterized by press-sintering at a temperature of 1900 to 2050 ° C. and a pressure of 20 to 60 MPa for 1 to 12 hours. And a manufacturing method thereof.

In the step (b), a liquid phase of Y-Sc-Zr-Si-OCN is formed and densified by a liquid phase sintering mechanism. The silicon carbide-zirconium carbonitride (SiC-Zr ₂ CN) composite material.

Further, in step (b), silicon nitride doped with nitrogen atoms (N) is precipitated and grown from the Y-Sc-Zr-Si-OCN-based liquid phase through a dissolution-reprecipitation mechanism Zirconium carbonitride (SiC-Zr ₂ CN) composite material.

In another aspect of the present invention, there is provided a silicon carbide-zirconium carbonitride (SiC-Zr ₂ CN) composite material produced by the above method.

It is also preferable that the electrical resistivity at room temperature is 4.4 x 10 ^-4 to 1.1 x 10 ^-2 Ωcm and the thermal conductivity at room temperature is 96 to 190 W / Silicon-zirconium carbonitride (SiC-Zr ₂ CN) composite material.

The present invention also provides a silicon carbide-zirconium carbonitride (SiC-Zr ₂ CN) composite material having a relative density of 98% or more.

According to the method for producing a composite material of silicon carbide-zirconium carbonitride (SiC-Zr ₂ CN) according to the present invention, yttrium oxide (Y ₂ O 3) is added as a sintering additive to β-SiC and zirconium nitride powders, Sc-Zr-Si-OCN is formed by sintering in a nitrogen (N ₂ ) atmosphere by adding a mixed powder of zirconium oxide (ZrO ₃ ) and scandium oxide (Sc ₂ O ₃ ) beta phase to the alpha phase and promotes densification by means of a liquid phase sintering mechanism and further promotes densification by means of a dissolution-precipitation mechanism by introducing nitrogen doped (N-doped) silicon carbide particles And zirconium carbonitride (Zr ₂ CN) grains excellent in electric conductivity are synthesized in-situ to provide excellent electric conductivity having electric conductivity improved by at least 10 times compared with monolithic silicon carbide Manufacture of ceramic composite materials Can.

1 is an X-ray diffraction (XRD) pattern of a silicon carbide (SiC) composite specimen to which monolithic silicon carbide (SiC) specimen and zirconium nitride (ZrN) are added.
2 is an image showing the microstructure of a silicon carbide (SiC) composite specimen to which monolithic silicon carbide (SiC) specimen and zirconium nitride (ZrN) are added.
Figure 3 shows a dot mapping image for Si, Zr, Y, Sc, C and N through SEM images and energy dispersive spectroscopy (EDS) on SZN35 specimens.
Figures 4 (a) and 4 (b) show the carrier concentration, carrier mobility and electrical conductivity of monolithic silicon carbide (SiC) specimens and zirconium nitride (ZrN) added silicon carbide As a function of the initial zirconium nitride (ZrN) content in the starting material composition.
5 shows the thermal conductivity and phonon mean free path of a silicon carbide (SiC) composite specimen to which a monolithic silicon carbide (SiC) specimen and zirconium nitride (ZrN) Graph.

In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

Embodiments in accordance with the concepts of the present invention can make various changes and have various forms, so that specific embodiments are illustrated in the drawings and described in detail in this specification or application. It should be understood, however, that the embodiments according to the concepts of the present invention are not intended to be limited to any particular mode of disclosure, but rather all variations, equivalents, and alternatives falling within the spirit and scope of the present invention.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In this specification, the terms "comprises ", or" having ", or the like, specify that there is a stated feature, number, step, operation, , Steps, operations, components, parts, or combinations thereof, as a matter of principle.

Hereinafter, the present invention will be described in detail.

The composition for preparing an electrically conductive silicon carbide-zirconium carbonitride composite material according to the present invention comprises 41.0 to 91.0% by weight of? -Carbide (? -SiC); 8.0 to 55.0 wt% zirconium nitride (ZrN); And 1.0 to 4.0% by weight of a sintering additive.

The β-silicon carbide exhibits excellent properties such as abrasion resistance, corrosion resistance, high thermal conductivity and chemical stability, and is mainly composed of ceramic composite material and is contained in a mixed powder for producing ceramic composite material in an amount of 41.0 to 91.0 wt% desirable.

On the other hand, the particle size of the β-silicon carbide is not particularly limited. However, in order to reduce the content of the sintering additive which causes the sintering property and the volume resistivity to increase depending on the high specific surface area, a micron or sub- ) ≪ / RTI > size.

It is preferable that the zirconium nitride (ZrN) is contained in the composition according to the present invention in an amount of 8.0 to 55.0% by weight in the mixed powder for producing the ceramic composite material.

The sintering additive is a mixture of yttrium oxide (Y ₂ O ₃ ) and scandium oxide (Sc ₃ O ₃ ), wherein yttrium oxide and scandium oxide (III) are mixed in a molar ratio of 1: 0.5 to 3 It is further preferable that the molar ratio of yttrium oxide: scandium oxide (III) is 1: 1.

Since yttrium oxide and scandium oxide are included in the composition according to the present invention as a sintering additive, a glassy liquid phase composed of Y-Sc-Zr-Si-OCN is formed during the sintering process to perfectly convert the silicon carbide into? Doped silicon carbide grains are grown by a dissolution-precipitation mechanism, and a high-conductivity zirconium-silicon carbide grains are grown by a liquid-phase sintering mechanism, The carbonitride (Zr ₂ CN) crystal grains are synthesized in-situ, so that a composite material with remarkably improved electrical conductivity can be produced.

In order to achieve the above effect, the sintering additive is preferably contained in an amount of 1.0 to 4.0% by weight in the composition for preparing an electrically conductive silicon carbide-zirconium carbonitride composite material according to the present invention. If the content of the sintering additive is less than 1.0% by weight, sintering is insufficient and the sintering property is poor due to insufficient sintering density, so that a dense ceramic composite material can not be manufactured. Thus, porosity is formed in the ceramic composite material and electrical conductivity and mechanical properties Can be lowered. If the content of the sintering additive exceeds 4.0% by weight, excess sintering additive remains in the silicon carbide grain boundary without a significant increase in the sintering density, thereby increasing the specific resistivity and decreasing the electric conductivity It is preferable to adjust the content of the sintering additive to the above range.

Next, a method of manufacturing the electrically conductive silicon carbide-zirconium carbonitride composite material according to the present invention will be described below.

A method for manufacturing an electrically conductive composite material of silicon carbide-zirconium carbonitride according to the present invention comprises the steps of: (a) mixing 41.0 to 91.0% by weight of? -Silicon carbide (? -SiC) powder; 8.0 to 55.0% by weight of zirconium nitride (ZrN) powder; And 1.0 to 4.0% by weight of a sintering additive powder; And (b) sintering the mixed powder obtained in the step (a) under a nitrogen (N ₂ ) atmosphere to produce a silicon carbide-zirconium carbonitride (SiC-Zr ₂ CN) composite material.

In step (a), β-silicon carbide (β-SiC) powder, zirconium nitride (ZrN) powder; And 1.0 to 4.0% by weight of a sintering additive powder to prepare a mixed powder composition for preparing the silicon carbide-zirconium carbonitride composite material.

Further, in this step, the step of grinding the mixed powder may be further carried out as necessary to form a mixed powder having a uniform particle size and a high specific surface area. In order to crush the mixed powder, various well-known powder crushing methods may be used. For example, an oil-based ball milling method in which a mixed powder is mixed and dispersed in an organic solvent such as ethanol and pulverized using zirconia balls or the like is used But can be configured to crush the powder using various methods without being limited to these methods.

Next, the step (b) is a step of producing a sintered body composed of a silicon carbide-zirconium carbonitride composite material under a nitrogen (N ₂ ) atmosphere using the mixed powder obtained in the step (a).

In the present invention, the mixed powder of the above-mentioned composition is sintered in a nitrogen (N ₂ ) atmosphere to grow silicon carbide particles doped with nitrogen, and zirconium carbonitride (Zr ₂ CN) situ and synthesized to produce an excellent electroconductive ceramic composite material having an electrical conductivity up to 10 times higher than that of monolithic silicon carbide.

More specifically, when sintering in a nitrogen (N ₂ ) atmosphere using the mixed powder, the sintering additive composed of Y ₂ O ₃ -Sc ₂ O ₃ is composed of silicon carbide (SiC), silicon dioxide on the surface of silicon carbide Zr-Si-OCN liquid phase is formed by reacting with zirconium (ZrO ₂ ) on the surface of zirconium nitride, zirconium nitride (ZrN ₂ ), and zirconium nitride, and the liquid phase is mixed with a silicon carbide-zirconium carbonitride composite It is possible to densify the material and induce grain growth of the electrically conductive silicon carbide doped with nitrogen atoms (N) by a dissolution-precipitation mechanism in the course of densification, and to induce the growth of zirconium carbonitride (Zr ₂ CN) is formed, whereby a silicon carbide-zirconium carbonitride composite material having high electrical conductivity can be obtained.

Meanwhile, the step (b) is preferably, but not necessarily, performed by pressure sintering under a nitrogen atmosphere at a temperature of 1900 to 2050 ° C and a pressure of 20 to 60 MPa for 1 to 12 hours.

According to the method for producing a composite material of silicon carbide-zirconium carbonitride (SiC-Zr ₂ CN) according to the present invention, which is described in detail above, yttrium oxide (SiC) is added as a sintering additive to? -Silicon carbide (? SiC) and zirconium nitride A glassy liquid phase composed of Y-Sc-Zr-Si-OCN is formed by adding a mixed powder of Y ₂ O ₃ and scandium oxide (Sc ₂ O ₃ ) and sintering in a nitrogen (N ₂ ) atmosphere It is possible to completely suppress the phase transformation of silicon carbide from? Phase to? Phase, accelerate densification by means of a liquid phase sintering mechanism, and further promote the N-doped by dissolution-precipitation mechanism. Silicon carbide grains are grown and zirconium carbonitride (Zr ₂ CN) grains with excellent electrical conductivity are synthesized in-situ to have an electrical conductivity of at least 10 times higher than that of monolithic silicon carbide Superior Electrical Conductivity Cera It is possible to manufacture a composite material.

Hereinafter, the present invention will be described in more detail with reference to examples.

The embodiments presented are only a concrete example of the present invention and are not intended to limit the scope of the present invention.

<Examples>

Y ₂ O ₃ powder (99.99%) was added to a commercial β-SiC powder (~ 0.5 μm, Grade BF-17, HC Starck, Berlin, Germany), ZrN powder (Kojundo Chemical Laboratory Co., Ltd., Sakado- , Kojundo Chemical Laboratory Co., Ltd.) and ScO ₃ powder (99.9%, Kojundo Chemical Laboratory Co., Ltd.) were used as starting materials.

The five mixed powder batches listed in Table 1 below were mixed in ethanol for 24 hours using SiC balls and polypropylene containers. As can be seen in Table 1 below, the ZrN contents of the five batches were 0, 4, 10, 20, and 35 vol%, respectively. The content of the additive was 2 vol%, and the molar ratio of Sc ₂ O ₃ and Y ₂ O was fixed at 1: 1.

The milled slurry was dried and sieved using a sieve (60 mesh) and sintered by hot press at a pressure of 40 MPa at 2000 ^° C for 3 hours under a nitrogen atmosphere.

Psalm name Batch composition (vol%) Batch composition (wt%) theory
density
(g / cm ³ ) opponent
density
(%) Room temperature heat capacity
(J / (gK)) Room temperature thermal diffusivity
(mm ² / s) SZN0 98.00% SiC
+ 1.13% Y ₂ O ₃
+ 0.87% Sc ₂ O ₃ 97.280% SiC
+ 1.026% Sc ₂ O ₃
+ 1.694% Y ₂ O ₃ 3.240 98.9 0.667
± 0.000 92.0
± 1.3 SZN4 96.00% SiC
+ 4.00% ZrN
+ 1.13% Y ₂ O ₃
+ 0.87% Sc ₂ O ₃ 88.832% SiC
+ 8.567% ZrN
+ 0.986% Sc ₂ O ₃ + 1.615% Y ₂ O ₃ 3.403 98.5 0.689
± 0.000 82.4
± 0.3 SZN10 88.00% SiC
+ 10.00% ZrN
+ 1.13% Y ₂ O ₃
+ 0.87% Sc ₂ O ₃ 77.590% β-SiC
+ 19.984% ZrN + 0.920% Sc 2 O 3 + 1.506% Y 2 O 3 3.647 98.7 0.605
± 0.000 75.8
± 0.2 SZN20 78.00% SiC
+ 20.00% ZrN
+ 1.13% Y ₂ O ₃
+ 0.87% Sc ₂ O ₃ 61.864% beta-SiC
+ 35.953% ZrN
+ 0.828% Sc ₂ O ₃ + 1.355% Y ₂ O ₃ 4.055 99.5 0.715
± 0.000 55.1
± 0.1 SZN35 63.00% SiC
+ 35.00% ZrN
+ 1.13% Y ₂ O ₃
+ 0.87% Sc ₂ O ₃ 43.425% β-SiC
+ 54.678% ZrN + 0.719% Sc 2 O 3 + 1.178% Y 2 O 3 4.666 99.0 0.570
± 0.000 38.1
± 0.1

<Experimental Example 1> Microstructure and phase analysis

The relative density of the monolithic SiC specimen (SZN0) prepared by the hot press process from the mixed powder of SiC-2 vol% Y ₂ O ₃ -Sc ₂ O ₃ was 98.9% and the relative density of ZrN Were also densified to have a relative density of 98.5% or more (see Table 1 above). These results indicate that the addition of ZrN in an amount of 4 to 35 vol% does not adversely affect the densification of the SiC-Zr ₂ CN composite.

In monolithic SiC specimens, the Y ₂ O ₃ -Sc ₂ O ₃ additive reacts with the SiO ₂ formed on the surface of the SiC particles to form a Y-Sc-Si oxide liquid phase during the heating process. Y-Sc-Si - Oxycarbonitride (OCN) liquid phase is formed by dissolving nitrogen and SiC forming sintering atmosphere with increasing temperature. The Y-Sc-Si-OCN liquid phase can improve the density of the specimen through liquid-phase sintering.

Similarly, in the case of the SiC-Zr ₂ CN composite, the Y ₂ O ₃ -Sc ₂ O ₃ additive reacts with SiO ₂ and ZrO ₂ derived from SiC and ZrN, respectively, in the heating process to form a Y-Sc-Zr- . As the temperature increases, the Y-Sc-Zr-Si-OCN liquid phase is formed by dissolving nitrogen, SiC and ZrN forming the sintering atmosphere as the temperature increases. The Y-Sc-Zr-Si-OCN liquid phase improved the density of the specimen through liquid phase sintering.

1 is an X-ray diffraction (XRD) pattern of a monolithic SiC specimen and a ZrN added SiC composite specimen. The XRD analysis results can be summarized as follows. That is, (1) the monolithic SiC (SZNO) is composed of only β-SiC (3C, JCPDS 29-1129) and (2) the phase transformation from β to α phase of SiC is completely inhibited during the hot pressing process in all the specimens . And (3) ZrN particles were converted to Zr ₂ CN phases (JCPDS 71-6065, represented by triangles in FIG. 1) by bonding with carbon particles from neighboring β-SiC particles during sintering.

The result is a monolithic SiC (SZN0) in the Y-Sc-Si-OCN liquid, SiC-Zr ₂ CN complex in the Y-Sc-Zr-Si- OCN liquid phase is formed, and a temperature of 2000 ^o C under the environment of 40 MPa pressure , The nitrogen atmosphere suppresses the phase transformation from β phase to α phase of SiC. Meanwhile, the reaction in which Zr ₂ CN is formed in situ can be expressed by the following chemical reaction formula.

_{4ZrN + 2SiC → 2Zr 2 CN +} 2Si (liquid) + N 2 (gas)

In this reaction, Si in liquid phase and N ₂ in gaseous phase are soluble in Y-Sc-Zr-Si-OCN liquid phase. Another possible mechanism is that the Zr ₂ CN phase precipitates from the Y-Sc-Zr-Si-OCN liquid phase during sintering and cooling. According to the chemical equation ZrN as the content of 4, 10, 20, and increased to 35 vol% on the content of Zr ₂ CN can be calculated as 8.5, 19.8, 35.6 and 54.2%, respectively. On the other hand, the content of Zr ₂ CN measured by the Rietveld refinement method was 10.2%, 20.6%, 35.6% and 54.4%, respectively, as the ZrN content increased to 4, 10, 20 and 35 vol% appear. In other words, the Zr ₂ CN contents in the SZN 20 and SZN 35 specimens were almost the same as the measured values and the calculated values, while the SZN 4 and SZN 10 specimens had relatively low Zr ₂ CN peaks. As a result, the Zr ₂ CN content Respectively. Similar results have been reported for SiC-Ti ₂ CN composites made from β-SiC, TiN, and 2 vol% Y ₂ O ₃ -Sc ₂ O ₃ additives.

Fig. 2 shows the microstructure of the monolithic SiC and SiC-Zr ₂ CN composite specimens, the characteristics of which can be summarized as follows.

(1) Both monolithic SiC and SiC-Zr ₂ CN composites showed equiaxed SiC grains, indicating that no phase transformation of β-phase to α-phase of SiC occurred in all specimens. For reference, the phase transformation from Si phase to beta phase is generally known to cause faceting of SiC grains. The results are consistent with the XRD analysis results (see FIG. 1).

(2) As the ZrN content increased from 0 to 35 vol% in the mixed powder, the average particle size of SiC decreased from 5.3 to 2.7 ㎛, indicating that ZrN acted as a grain growth inhibitor.

(3) The average particle size of Zr ₂ CN increased from 2.0 to 3.8 ㎛ as the ZrN content increased from 0 to 35 vol% in the raw mixed powder, indicating that the Zr ₂ CN grain growth occurred during the hot pressing process do.

(4) The size and shape of Zr ₂ CN grains were different depending on the position of the grains. Small and spherical Zr ₂ CN grains (<1 μm) were mostly trapped in SiC grains while large and irregular Zr ₂ CN grains ≥ 1 μm) were located at grain boundaries or at multigrain junctions. This phenomenon is presumably due to the fact that the small and spherical Zr ₂ CN crystal grains are formed by precipitation from the liquid phase and are trapped in the growing SiC crystal grains, and large and irregular Zr ₂ CN grains are formed through the reaction according to the above chemical reaction formula, This is because it is caused by deformation. Like ZrN, Zr ₂ CN also has a flexible (ductility) at a temperature to perform a hot press process. The size and shape of Zr ₂ CN grains observed in SiC-Zr ₂ CN composites are supported by similar results for other composites such as SiC-Ti ₂ CN composite and SiC-Si ₃ N ₄ nano / micro composite.

Figure 3 shows a dot mapping image for Si, Zr, Y, Sc, C and N through SEM images and energy dispersive spectroscopy (EDS) on SZN35 specimens. The EDS results show that (1) the light gray grains correspond to the Zr ₂ CN phase consisting of Zr, C and N, and (2) the dark gray grains are mainly N-doped, consisting mainly of Si and C, SiC &lt; / RTI &gt; From these results, it can be seen that the SZN35 specimen consists of N-doped SiC grains and Zr ₂ CN grains. Y and Sc are located on or near Zr ₂ CN grains, and these elements appear to have affinity for Zr ₂ CN grains. As the N-doped SiC grains grow during the sintering process, the N atoms are substituted at the C-positions to form a donor level (N _c ) near the conduction band, so that the SiC-Zr ₂ CN complexes contain nitrogen Doping can have a high carrier density.

<Experimental Example 2> Examination of Electrical Properties

Figures 4 (a) and 4 (b) show the carrier concentration, carrier mobility and electrical conductivity of monolithic SiC and SiC-Zr ₂ CN composites as a function of initial ZrN content. The monolithic SiC and SiC-Zr ₂ CN composites obtained by sintering together with Y ₂ O ₃ -Sc ₂ O ₃ were found to be n-type semiconductors. The carrier concentration of the monolithic SiC (SZNO) obtained by sintering with the Y ₂ O ₃ -Sc ₂ O ₃ additive was 7.4 × 10 ¹⁹ cm ^-3 . As the ZrN content increased from 4 vol% to 35 vol%, the carrier concentration Was increased from 2.6 x 10 ²⁰ cm ^-3 to 7.9 x 10 ²⁰ cm ^-3 . The carrier concentration of SZNO is selected from the group consisting of N-doped 4H-SiC epitaxial layer and Y ₂ O ₃ , AlN-Y ₂ O ₃ , AlN-Er ₂ O ₃ , and Y ₂ O ₃ -RE SiC ceramics sintered with ₂ O ₃ (RE = Sm, Gd, Lu) were higher than those reported previously. During the hot pressing process of the SZNO specimen, the nitrogen which forms the sintering atmosphere is dissolved to form the Y-Sc-Si-OCN liquid phase. Under current sintering conditions, effective nitrogen doping is carried out in the SiC lattice through grain growth of β-SiC by dissolution-precipitation in the Y-Sc-Si-OCN liquid phase. These results Y-Si-OCN liquid, AlN-Er SiC ceramics sintered by adding ₂ O ₃ in the Y-Sc-Si-OCN liquid phase, SiC ceramics sintered by the addition of Y ₂ O ₃ formed on SZN0 specimen (OCN) liquid phase, such as the Er-Al-Si-OCN liquid phase in the SiC ceramics and the Dy-Al-Si-OCN liquid phase in the SiC ceramics sintered with AlN-Dy ₂ O ₃ . The electrical conductivity (3.8 x 10 ³ (Ωm) ^-1 ) of the SiC specimen (SZN 0) in this study was calculated as the electrical conductivity (7.7 × 10 ² Ωm ^-1 ) of the SiC ceramics sintered with Y ₂ O ₃ ), Electrical conductivity of SiC ceramics sintered with AlN-Y ₂ O ₃ (1.3 x 10 ³ (Ωm) ^-1 ), electrical conductivity of SiC ceramics sintered with AlN-Er ₂ O ₃ ^{3 (Ωm) -1), AlN} -Dy 2 O electric conductivity _(1.3 x 10 ³ _(Ωm) of the SiC ceramics sintered by the addition of ₃ ^-1), Y ₂ O ₃ -Sm ₂ O ₃ sintered by the addition of (1.8 x 10 ³ (Ωm) ^-1 ) of the SiC ceramics sintered with addition of Y ₂ O ₃ -Gd ₂ O ₃ and the electrical conductivity of the SiC ceramics (2.5 x 10 ³ (Ωm) ^-1 ) Respectively.

The high electrical conductivity of SZNO is (1) effective nitrogen doping in the SiC lattice by grain growth through dissolution-precipitation in the Y-Sc-Si-OCN liquid phase, (2) very low electrical conductivity (2 vol%) was added to the sintering additive.

ZrN is added to SiC together with the Y ₂ O ₃ -Sc ₂ O ₃ additive to change the liquid phase composition from Y-Sc-Si-OCN to Y-Sc-Zr-Si-OCN in the hot pressing process . The reason why the SiC-Zr ₂ CN composite has a higher carrier concentration than the monolithic SiC specimen (SZNO) is that the Y-Sc-Zr-Si-OCN liquid phase is composed of Y-Sc-Si Suggesting that it has a higher nitrogen content than the -OCN liquid phase. Therefore, the SZN35 specimen has the highest carrier concentration (7.9 × 10 ²⁰ cm ^-3 ) compared to other specimens. Interestingly, the carrier concentration of the SZN35 specimen is close to the upper limit of nitrogen solubility (8.0 x 10 ²⁰ cm ^-3 ) of SiC. These results indicate that the SiC grains in the composite under the sintering conditions of this embodiment were effectively doped with nitrogen in the Y-Sc-Zr-Si-OCN liquid phase. The carrier mobility of monolithic SiC was 3.2 cm ² / Vs. On the other hand, the carrier mobility of the composite specimen increased from 2.2 to 18 cm ² / Vs as the ZrN content increased from 4 to 35 vol%. As a result, the electrical conductivity of SiC-Zr ₂ CN composite specimens increased from 9.1 x 10 ³ to 2.3 x 10 ⁵ (Ωm) ^-1 as the ZrN content increased from 4 to 35 vol% Which is higher than the electrical conductivity of the specimen (3.8 x 10 ³ (Ωm) ^-1 ).

The SiC-Zr ₂ CN composite exhibits high electrical conductivity as described above because (1) the nitrogen-doped (N- doped SiC crystal grains grow, (2) electrically conductive Zr ₂ CN grains are included, and (3) electrically insulating additives are included in small amounts.

According to previous _{studies, SiC-MoSi 2, SiC-} NbC-Ti, SiC-Ti 2 complex is 10 ² to 10 ⁵ at room temperature containing the SiC and a conductive (phase), such as CN, and SiC-graphene (Ωm) ^{- 1} , and the electrical conductivity values are comparable to the electrical conductivity values of the SiC-Zr ₂ CN composite specimens of this embodiment. However, the electric conductivity (2.3 x 10 ⁵ (Ωm) ^-1 ) of the SZN 35 specimen in this embodiment is higher than the electric conductivity of the SiC-MoSi ₂ , SiC-NbC-Ti, and SiC-graphene complexes, It shows a high value similar to the SiC-Ti ₂ CN complex comprising the% TiN. These results indicate that the addition of ZrN to SiC can effectively improve the electrical conductivity of SiC ceramics.

<Experimental Example 3> Consideration of thermal properties

Figure 5 shows the thermal properties, i.e., thermal conductivity and phonon mean free path, of the monolithic SiC and SiC-Zr ₂ CN composite specimens. Table 1 shows the heat capacity and thermal diffusivity of the specimen measured at room temperature (RT).

Monolithic SiC the thermal conductivity of the sample is 199.6 W / mK, increasing the ZrN content up to 35 vol% the thermal conductivity of the composite specimens were gradually reduced to 96.7 W / mK, which (1) the thermal conductivity of the Zr ₂ CN degrees ( 43W / mK) is lower than that of SiC, (2) the grain size of SiC decreases (5.3 → 2.7 μm), and (3) the interfacial area between SiC and Zr ₂ CN increases. Generally, in semiconducting SiC ceramics, heat is conducted mainly by phonons and only partly by electrons, although both phonons and electrons can conduct heat in the material. In order to investigate the effect of electron contribution on the thermal conductivity of monolithic SiC and SiC-Zr ₂ CN composites, the electron contribution to thermal conductivity was evaluated using the Wiedemann-Franz law according to the following equation .

Wherein, σ, T, and L represents a respective electrical conductivity, temperature and number of Lorentz ^{(Lorenz number, 2.44 x 10 -8} WΩK -2). According to Bidemann-Franz's law, the electron contribution to thermal conductivity increases from 0.01 to 1.71% as the ZrN content increases from 0 to 35 vol%, but this electron contribution is negligible compared to the contribution of phonons. Therefore, heat is mostly conducted by phonons in monolithic SiC and SiC-Zr ₂ CN composites. In polycrystalline ceramics, phonons can be scattered by chemical or structural defects. Representatively, phonon-defect scattering and phonon-grain boundary scattering are examples. In SiC and Zr ₂ CN ceramics, oxygen is a major impurity in the lattice that affects the thermal conductivity of the non-oxide ceramics.

The phonon mean free path of monolithic SiC and SiC-Zr ₂ CN composites at room temperature was measured as 24.0 (SZN0), 21.5 (SZN4), 20.0 (SZN10), 14.7 (SZN20) and 10.7 nm (SZN35) The decreasing tendency of thermal conductivity with increasing ZrN content was confirmed to be consistent with the tendency of phonon mean free path in each specimen. Since the average particle sizes of SiC and Zr ₂ CN in monolithic SiC and SiC-Zr ₂ CN composites are 2.7 to 5.3 μm and 2.0 to 3.8 μm, respectively, the phonon average free path of the monolithic SiC and SiC-Zr ₂ CN composite is SiC and Zr ₂ CN grain size, thermal conductivity is mainly affected by lattice defects and secondarily by phonon-grain boundary scattering.

Claims (10)

41.0 to 91.0% by weight of beta -silicon carbide (beta -SiC); 8.0 to 55.0 wt% zirconium nitride (ZrN); And 1.0 to 4.0% by weight of a sintering additive,
Wherein the sintering additive comprises silicon carbide-zirconium carbonitride (SiC-Zr ₂ (Y ₂ O ₃ )), wherein the sintering additive comprises yttria (Y ₂ O ₃ ) and scandium oxide (Sc ₂ O ₃ ) in a molar ratio of 1: CN) composites. The method of claim 1, wherein the β- silicon carbide micron (micron) or sub-micron (sub-micron) powder of the silicon carbide which is characterized-zirconium carbonitride _(Zr-2 CN SiC) composite material for producing the composition. delete (a) 41.0 to 91.0% by weight of? -silicon carbide (? -SiC) powder; 8.0 to 55.0% by weight of zirconium nitride (ZrN) powder; And 1.0 to 4.0% by weight of a sintering additive powder; And
(b) sintering the mixed powder obtained in the step (a) under a nitrogen (N ₂ ) atmosphere to produce a silicon carbide-zirconium carbonitride (SiC-Zr ₂ CN)
Wherein the sintering additive comprises silicon carbide-zirconium carbonitride (SiC-Zr ₂ (Y ₂ O ₃ )), wherein the sintering additive comprises yttria (Y ₂ O ₃ ) and scandium oxide (Sc ₂ O ₃ ) in a molar ratio of 1: CN) composite material. 5. The method of claim 4,
Zirconium carbonitride (SiC-Zr ₂ CN) composite material in the step (b) is characterized by press-sintering at a temperature of 1900 to 2050 ° C. and a pressure of 20 to 60 MPa for 1 to 12 hours . 6. The method of claim 5,
Zirconium carbonitride (SiC-Zr ₂ CN) is formed by forming a Y-Sc-Zr-Si-OCN-based liquid phase in the step (b) and densifying it through a liquid phase sintering mechanism. Method of manufacturing composite material. The method according to claim 6,
Wherein the silicon carbide doped with nitrogen atoms (N) is precipitated and grown from the Y-Sc-Zr-Si-OCN-based liquid phase in the step (b) through a dissolution-precipitation mechanism. (SiC-Zr ₂ CN) composite material. A silicon carbide-zirconium carbonitride (SiC-Zr ₂ CN) composite material produced by the method according to any one of claims 4 to 7. 9. The method of claim 8,
Characterized in that the electrical resistivity at room temperature is 4.4 x 10 ^-4 to 1.1 x 10 ^-2 ? Cm and the thermal conductivity at room temperature is 96 to 190 W / mK. Zirconium carbonitride (SiC-Zr ₂ CN) composite material. 9. The method of claim 8,
(SiC-Zr ₂ CN) composite material having a relative density of 98% or more.

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