KR20150082790A - MANUFACTURING METHOD AND APPARATUS OF SiC COATING LAYERS - Google Patents

Abstract

Disclosed are a method and an apparatus to form a silicon carbide coating layer. According to the present invention, the method to form a silicon carbide coating layer comprises: a powder forming step of forming a silicon carbide powder coating layer; a drying step of drying powder formed in the powder forming step; and a coating layer forming step of coating powder dried in the drying step to a base metal in a deposition chamber using an aerosol deposition method. Additionally, in the coating layer forming step, the base metal may be a zirconium alloy and a feeding gas consisting of helium. According to the present invention, in forming a silicon carbide coating layer, the aerosol deposition method is used based on the feeding gas consisting of helium in a base metal of zirconium alloy; thereby forming a coating layer having a thickness of more than 90 μm and a low porosity while minimizing a generation of oxides and changes in phase, and accordingly forming a coating layer with excellent wear and corrosion resistance.

Description

TECHNICAL FIELD [0001] The present invention relates to a method of forming a silicon carbide coating layer,

More particularly, the present invention relates to a method of forming a silicon carbide coating layer on the surface of a base material so as to improve heat resistance, corrosion resistance or wear resistance of components constituting a machine and mechanism, And more particularly, to a method and apparatus for forming a silicon carbide coating layer capable of minimizing oxide formation or phase change during formation and increasing the thickness of a coating layer quickly.

Silicon Carbide (SiC) has been used for insulation materials, engine parts, cutting tools, and precision machine tools because of its excellent heat resistance, corrosion resistance and abrasion resistance. Various kinds of ceramic thin films including SiC are introduced on the surface of parts to improve wear resistance and corrosion resistance of parts.

Specifically, such a ceramic thin film can be manufactured through a thin film manufacturing process such as plasma spraying and chemical vapor deposition (CVD).

Korean Patent No. 10-1158343 discloses a " silicon carbide structure and its manufacturing method ", and specifically discloses a method of manufacturing a silicon carbide structure by depositing silicon carbide on a base plate by chemical vapor deposition to form a silicon carbide layer, Removing the silicon carbide structure to obtain a silicon carbide structure; annealing the silicon carbide structure to lower electrical conductivity; and removing the silicon carbide structure to a thickness of 200 mu m or more by machining the upper and lower surfaces of the silicon carbide structure, respectively In this case, the silicon carbide is deposited by CVD and is then formed through post-processing and post-processing to lower the electric conductivity level required for the protection ring of the plasma apparatus, so that the electric conductivity can be adjusted without using any additive. .

However, in the case of forming the silicon carbide by using the plasma spray method, it is usually possible to form a thin coating layer having a thickness of 3 to 5 占 퐉, but it is difficult to form a coating layer having a thickness of 100 占 퐉 or more and a powder sprayed with a plasma flame close to 10,000 占 폚 is dissolved There is a problem that oxides are present in the coating layer or phase decomposition occurs.

Also, in the case of CVD, it is only possible to obtain a thin coating layer having a thickness of 0.5 to 2 占 퐉, and it takes much time to manufacture the coating layer.

(0001) Korean Patent No. 10-1158343 (Published on June 22, 2012)

It is an object of the present invention to provide a method and apparatus for forming a silicon carbide coating layer capable of minimizing oxide formation or phase change during formation of a coating layer, lowering porosity, and forming a thick coating layer of 100 탆 or more.

This object is achieved by a method for manufacturing a silicon carbide powder, comprising: a powder forming step of forming a silicon carbide powder; A drying step of drying the powder formed in the powder forming step; And a coating layer forming step of coating the base material with the powder dried in the drying step by an aerosol deposition method inside the deposition chamber.

In the coating layer forming step, the base material may be composed of an Fe-based, Al-based, Cu-based, Ni-based, Zr-based or Mg-based metal.

In the coating layer formation step, the feed gas may be composed of helium, nitrogen or air.

The powder formed in the powder forming step may be ball milled with an ingot manufactured by the following formula to have an average particle size of 1 to 40 탆.

The drying step may be performed in a vacuum drier at 100 to 200 ° C for 1 to 2 hours.

In the coating layer forming step, a flow rate of the supplied gas into the deposition chamber is 1 to 30 L / min, a distance between the nozzle and the base material is 3 to 10 mm, and a moving speed of the nozzle is 0.5 to 5 mm / sec.

The pressure of the deposition chamber may be in the range of 10 * 10 ^-2 to 20 torr.

The above object can also be accomplished by a method of manufacturing a semiconductor device, comprising: a powder forming part in which a silicon carbide powder is formed; A drying unit for drying the powder formed in the powder forming unit; A powder storage tank in which powder dried in the drying unit is stored; A feed gas storage tank in which the feed gas path is stored; A deposition chamber in which the powder stored in the powder storage tank and the feed gas stored in the feed gas storage tank are mixed and discharged to the base material; And a vacuum pump for reducing the pressure inside the deposition chamber to a vacuum state.

And a control unit for controlling a flow rate of the ink ejected through the nozzle, a distance between the nozzle and the base material, and a movement of the nozzle.

According to the present invention, an aerosol deposition method is used to form a silicon carbide coating layer, and an aerosol deposition method based on a carrier gas composed of helium is used for a metallic base material. A coating layer having a low porosity can be formed, and thus a coating layer having excellent abrasion resistance and corrosion resistance can be formed.

Further, by forming a silicon carbide coating layer using zirconium as a base material, it is possible to form a reactor having excellent abrasion resistance and corrosion resistance.

1 is a flowchart showing a method of forming a silicon carbide coating layer according to an embodiment of the present invention;
2 is a schematic view of an apparatus for forming a silicon carbide coating layer according to another embodiment of the present invention,
FIG. 3 is a graph showing the shape of the silicon carbide powder used in the present invention, (b) the particle size distribution, (c) the XRD phase analysis result,
FIG. 4 is a SEM observation of a silicon carbide coating layer prepared according to the present invention after preparation of a specimen in a cross-section direction,
5 shows porosity of a silicon carbide coating layer produced according to the present invention,
6 is a view showing a silicon carbide coating layer manufactured according to the present invention at high magnification using FE-SEM,
7 is a graph showing the results of comparative analysis of XRD (X-ray diffraction) peaks of an initial powder, a prepared coating layer, and a base material Zr,
8 is a graph showing a result of performing a peak gator test of a silicon carbide coating layer produced according to the present invention,
FIG. 9 is a view showing a surface of a coating layer prepared according to the present invention as an image of the surface roughness using a scanning probe microscope (SPM)
10 is a view showing a wear surface of the coating layer and the base material after the wear test,
11 is a view showing a state in which a coating layer and an oxide layer are formed on a base material.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description of the present invention, the well-known functions or constructions are not described in order to simplify the gist of the present invention.

FIG. 1 is a flow chart showing a method of forming a silicon carbide coating layer according to an embodiment of the present invention, and FIG. 2 is a schematic view of a silicon carbide coating layer forming apparatus according to another embodiment of the present invention.

The apparatus for forming a silicon carbide coating layer according to the present invention includes a powder forming unit 20, a drying unit 30, a powder storage tank 40, a feed gas storage tank 10, a deposition chamber 50 and a vacuum pump 60, .

The powder forming part 20 is a constitution for forming the silicon carbide in powder form. In the powder forming part 20, the silicon carbide powder can be formed by various conventional methods. However, the Acheson method (3C + SiO ₂ → SiC + 2CO), and then ball milling the ingot to form a silicon carbide powder.

The drying part 30 is for drying the formed silicon carbide powder and may be formed by a vacuum drying oven.

In the feed gas storage tank 10, helium (He), nitrogen (N ₂ ) or air (Air) may be stored and used as the feed gas. In particular, helium is preferably used as the feed gas, 40) so as to form an aerosolized powder.

The powder storage tank 40 stores the powder dried in the drying unit 30 and is connected to the drying unit 30 and the feed gas storage tank 10. The aerosol powder in the powder storage tank 40 is accelerated by the pressure difference between the powder storage tank 40 and the deposition chamber 50 to be supplied into the deposition chamber 50.

Inside the deposition chamber 50, there is provided a nozzle 51 formed so as to discharge the aerosolized powder toward the base material.

The deposition chamber 50 is also connected to a control unit for controlling the flow rate of the gas ejected through the nozzle 51, the distance between the nozzle 51 and the base material, and the movement of the nozzle 51, So that the flow rate of the powder in the aerosol state to be moved and sprayed can be adjusted.

The vacuum pump 60 decompresses the inside of the deposition chamber 50 to be in a vacuum state so that the powder is rapidly injected into the deposition chamber 50 by the pressure difference between the nozzle 51 and the deposition chamber 50 .

Hereinafter, a method of forming a silicon carbide coating layer will be described based on such a silicon carbide coating layer forming apparatus.

The method for forming a silicon carbide coating layer according to the present invention includes a powder forming step (S10), a drying step (S20) and a coating layer forming step (S30).

In the powder forming step S10, silicon carbide (SiC) powder is formed in the powder forming part 20 and the silicon carbide powder formed in the powder forming step S10 is formed of an ingot Ingot is ball milled to have an average particle size of 30 to 40 mu m.

Fig. 3 shows (a) shape, (b) particle size distribution, and (c) XRD phase analysis results of the silicon carbide powder used in the present invention. The average particle size was 37.4 ㎛ and it had an angular shape. As a result of XRD analysis, it was found that the powder other than α-SiC and β-SiC did not appear.

The drying step S20 is performed after the powder forming step S10 and the silicon carbide powder formed in the powder forming step S10 is dried in the drying step S20. Since the process according to the aerosol deposition to be described later is performed inside the chamber (the deposition chamber 50) in the vacuum atmosphere, it is sensitive to the moisture of the powder or the apparatus, and therefore, It may be carried out at 100 to 200 ° C for 1 to 2 hours, and particularly preferably at 100 ° C for 1 hour.

The coating layer forming step S30 is performed after the drying step S20 and the silicon carbide powder dried in the drying step S20 is coated on the base material by the aerosol deposition method in the deposition chamber 50. [ As described above, as the vacuum pressure is formed inside the deposition chamber 50, helium (He) stored in the feed gas storage tank 10 is fed toward the powder storage tank 40, and the powder in the aerosol state is supplied to the nozzle Is supplied to the inside of the deposition chamber (50) through the through hole (51).

In the method of forming a silicon carbide coating layer according to the present invention, the experiment is performed by adjusting the flow rate, the feed gas, the distance between the nozzle 51 and the base material in the process parameters in order to obtain optimum process conditions, Are shown in Table 1 below. The base material may be a metal or ceramic base material, but it is preferable that a Fe, Al, Cu, Ni, Zr or Mg base metal is used as the base material. In particular, (Zr) alloy used as a main material of the reactor (forming a silicon carbide coating layer by using zirconium as a base material to form a reactor material excellent in abrasion resistance and corrosion resistance), and blasting blasting was not performed, and the feed gas was made of Helium.

In the coating layer forming step S30, the flow rate of the supplied gas into the deposition chamber 50 is 10 to 30 L / min, the distance between the nozzle 51 and the base material is 5 to 6 mm, the moving speed of the nozzle 51 is 1 to 5 mm / sec < / RTI > However, as shown in Table 1, when manufactured at a flow rate of 10 L / min, a distance of 5 mm between the nozzle 51 and the base material, a moving speed of the nozzle 51 at 1 mm / sec, A coating layer having a thickness of 90 탆 or more and a low porosity can be formed while minimizing formation and phase change.

#One #2 Substrate Zr alloy (30 mm * 30 mm) Blasting No Carrier Gas He Gas Flow rate (L / min) 10 10 Chamber Pressure (torr) 4.0 * 10 ^-1 4.0 * 10 ^-1 Distance (mm) 5 5 Gun Traveling Speed (mm / sec) One One Pass 10 10

The prepared coating layer was mounted on a cross section, polished to SiC paper # 2000, and finely polished to a diamond paste (1 μm) level. SEM (Scanning Electron Microscope, Tescan, VEGA Ⅱ LMU) was used to confirm the formation of the coating layer, and the inside of the coating layer was observed while increasing the magnification. The coating layer was measured for porosity of the coating layer by using an image analyzer.

The initial powder, coating layer and Zr alloy were analyzed using micro-beam XRD (X-ray diffraction, D / MAX RAPID-S) to determine whether there was any oxide formation or phase change before and after the coating process. Respectively.

In addition, the shape and size of the initial powder were compared by observing the coating layer formed using FE-SEM (Field Emission Scanning Electron Microscope, Jeol, JSM-6700F) at a high magnification.

In addition, ball crater test was conducted to investigate the wear resistance characteristics of the prepared coating layer, and the wear amount of the coating layer and the base material was compared and analyzed. Silicon carbide powder having a size of 2 탆 was formed into slurry (water: powder = 4: 3) on a ball having a radius of 12.5 mm made of stainless steel and supplied at a rate of 1.15 g / min. Sliding distance 3 m , And a load of 0.2 N, respectively. The abrasion marks were observed with SEM, and the radius was measured three times using an image analyzer. The abrasion loss was calculated by the following equation and the wear resistance characteristics of the coating layer were investigated.

b: radius of abrasion (mm), R: radius of ball (mm)

In addition, the average roughness and surface shape of the surface were obtained by using SPM (Scanning Probe Microscopy, Seiko SPA-400), and the correlation between the amount of wear and the surface roughness was confirmed.

FIG. 4 shows the thicknesses of the prepared silicon carbide coating layers through SEM observation after preparation of specimens in the cross-section direction. FIGS. 4 (a) and 4 (b) 2 < / RTI > As a result of measurement with an image analyzer, it can be seen that a thick coating layer having a thickness of 90 탆 for # 1 and 150 탆 for # 2 was formed. In the case of a chemical vapor deposition (CVD) process, a coating layer is usually formed at a slow speed of 1 占 퐉 per hour, and in the case of plasma spraying, a thin film of usually 3 to 5 占 퐉 is formed. In the case of using the aerosol deposition method, it is easy to control the thickness of the coating layer and the forming speed (30 탆 / min) is faster than other steps.

Fig. 5 shows porosity of the produced silicon carbide coating layer.

As shown in FIG. 5, it can be seen that the size and shape of the initial powder and the powders that are stacked and broken are present as extreme fine particles which are not visible in the SEM image. In the coating layer formation step (S30) by the aerosol deposition, the ceramic material having high brittleness is laminated in a very fine particle state by fracture, and impact energy is transmitted to the inside of the particle due to collision with the base material, so that fracture and plastic deformation , Followed by the formation of a bond between the coating layer and the powder due to the collision, thereby forming a dense ceramic coating layer free from cracks.

The porosity of the prepared coating layer was 0.41% in case of # 1 and 0.50% in case of # 2 in Table 1, indicating that a high-density coating layer was formed. The porosity is the most basic and important measure in evaluating the properties of the coating layer. The lower the pressure of the deposition chamber 50 is, the higher the powder injection speed is, and the impact energy of the base material and the powder is increased, It is possible to form a coating layer having high porosity and low porosity.

FIG. 6 is a view of the silicon carbide coating layer observed at a high magnification using an FE-SEM, and FIGS. 6 (a) and 6 (b) show cases of # 1 and # 2 in Table 1, respectively. It can be seen that the powder having the initial size of 37.4 탆 and the angular shape has the size of several nanometers and the coating layer is formed in the form of very fine particles so that the initial shape can not be seen. In the coating layer forming step (S30), the powder is injected at a speed of 300 to 500 m / s to have a large kinetic energy. When the injected powder collides with the base material, the kinetic energy is converted into impact energy and the powder is broken. The coating layer is formed to form a dense coating layer.

7 is a comparative analysis result of the XRD (X-ray diffraction) peaks of the initial powder, the prepared coating layer, and the base material Zr. The XRD of the coating layer was measured with the cross section specimen, and not only the silicon carbide but also the base material (Zr) was also detected. In addition, only the base material was measured and compared with the coating layer peak.

The initial powder had α-SiC (Hexagonal structure) and β-Sic (Cubic structure) phases coexisting (α-SiC single phase and β-SiC single phase powders could be coated in addition to the two phases) The coating layer appeared the same as the initial powder phase. In the plasma spray process, X-ray diffraction (XRD) analysis of the coating layer simultaneously detects oxides (SiO ₂ ) together with α-SiC, β-SiC, and stainless steel. This is because when the silicon carbide powder is moved in a plasma jet SiC is decomposed into Si and C, and there is a part where the plasma is oxidized and stacked by the high temperature of the plasma jet.

On the contrary, the aerosol deposition process is performed through the coating process by RTIC (Room Temperature Impact Consolidation) phenomenon and does not cause oxide formation or phase change, but keeps the phase of the initial powder as it is. Can not be created.

FIG. 8 shows the results of performing a bolk gate test in order to confirm the wear resistance characteristics of the silicon carbide coating layer, and the average value obtained by performing three times for each specimen.

As a result of the experiment, the abrasion amount of 3.9 * 10 ^-5 [mm ³ ] for # 1, 3.10 * 10 ^-5 [mm ³ ] for # 2 and 12.9 * 10 ^-5 [mm ³ ] for the base material Zr appeared. Thus, it was found that the produced silicon carbide is superior in wear resistance even though it is a thin coating material as compared with a bulk form.

FIG. 9 is an image of the surface roughness of the coating layer obtained by SPM (Scanning Probe Microscopy), and FIG. 9 (a) and FIG. 9 (b) are the cases of # 1 and # 2 in Table 1, respectively. Roughness average (Ra) values were used as a way to quantify the surface roughness of the coating layer. The Ra value is an average within the measurement range of the absolute values of the length from the center line to the cross-sectional curve of the surface. (a) It can be seen that Ra is larger than # 2 in (b) # 2, and Ra means that the difference between the mountain and the bone is large and the roughness is large.

Fig. 10 is a view of the wear surface of the coating layer and the base material after the abrasion test, and Figs. 1 (a), 1 (c), 1 (b) and 1 (d) show the cases of # 1 and # 2 in Table 1, respectively. (a) Since # 1 has a large surface roughness, it appears to be in the form of abrasion and adhesion with a silicon carbide slurry, and it can be confirmed that debris is generated and aggregated. (b) The worn surface of # 2 has fewer debris than # 1, and only cracks are formed. It can be seen from (c) and (d) that the wear depth of # 1 is deeper than that of # 2 at high magnification. If the surface roughness of the abrasive surface is large, the portions where the stress is concentrated are broken, and these portions are broken and fall off with the abraded particles, resulting in deeper and worn-out wounds. Thus, although the porosity in the coating layer was lower than # 2 in # 1, it was found that the wear amount was increased by the surface roughness.

11 is a view showing a state in which a coating layer and an oxide layer are formed on a base material.

As shown in FIG. 11, it can be seen that the oxide layer (upper portion of the base material) is formed by the minute pores inside the silicon carbide coating layer, but the oxide layer is thinner than the uncoated portion (lower portion of the base material) As a result, it is possible to confirm the prevention of oxidation and the improvement of corrosion resistance by the silicon carbide thin film.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It is obvious to those who have. Accordingly, it should be understood that such modifications or alterations should not be understood individually from the technical spirit and viewpoint of the present invention, and that modified embodiments fall within the scope of the claims of the present invention.

10: Feed gas storage tank 20: Powder forming part
30: Drying section 40: Powder storage tank
50: deposition chamber 51: nozzle
60: Vacuum pump
S10: Powder forming step S20: Drying step
S30: Coating layer formation step

Claims (9)

A powder forming step of forming a silicon carbide powder;
A drying step of drying the powder formed in the powder forming step; And
And a coating layer forming step of coating the base material with the powder dried in the drying step by an aerosol deposition method inside the deposition chamber. The method according to claim 1,
Wherein the base material is an Fe-based, Al-based, Cu-based, Ni-based, Zr-based or Mg-based metal in the coating layer forming step. The method according to claim 1,
Wherein the feed gas in the coating layer forming step is helium, nitrogen, or air. The method according to claim 1,
Wherein the powder formed in the powder forming step is ball milled with an ingot manufactured by the following formula to have an average particle size of 1 to 40 占 퐉.

The method according to claim 1,
Wherein the drying step is performed in a vacuum drier at 100 to 200 DEG C for 1 to 2 hours. The method according to claim 1,
Wherein a flow rate of the supplied silicon into the deposition chamber is 1 to 30 L / min, a distance between the nozzle and the base material is 3 to 10 mm, and a moving speed of the nozzle is 0.5 to 5 mm / sec. A method of forming a carbide coating layer. 5. The method of claim 4,
Wherein the pressure of the deposition chamber is 10 * 10 < ^{-2 &} gt ^; to 20 torr. A powder forming portion in which a silicon carbide powder is formed;
A drying unit for drying the powder formed in the powder forming unit;
A powder storage tank in which powder dried in the drying unit is stored;
A feed gas storage tank in which the feed gas path is stored;
A deposition chamber in which the powder stored in the powder storage tank and the feed gas stored in the feed gas storage tank are mixed and discharged to the base material; And
And a vacuum pump for reducing the pressure inside the deposition chamber to a vacuum state. 9. The method of claim 8,
Further comprising a control unit for controlling a flow rate of the fluid discharged through the nozzle, a distance between the nozzle and the base material, and a movement of the nozzle.

Images