Silicon carbide abrasive and method of making same

Abstract

The present application relates to the technical field of silicon carbide preparation, and particularly relates to a silicon carbide abrasive and a preparation method thereof. The present application provides a preparation method of the silicon carbide abrasive, which comprises the following steps: uniformly mixing quartz sand, a carbon source and aluminum to obtain a mixture; and performing calcination treatment on the mixture to obtain the silicon carbide abrasive. The present application provides the silicon carbide abrasive and the preparation method thereof, and can provide a high-hardness silicon carbide abrasive.

Description

Technical Field

[0001] This invention relates to the field of silicon carbide preparation technology, and in particular to a silicon carbide abrasive and its preparation method. Background Technology

[0002] Silicon carbide abrasive is an advanced wear-resistant material. Its high hardness, stable chemical properties, and good thermal conductivity make it widely used in many fields such as electronics, metal processing, medical, and ceramics.

[0003] However, when silicon carbide abrasives are used to polish wafers with high hardness, their insufficient hardness leads to faster wear and shorter service life.

[0004] Therefore, in order to address the above-mentioned shortcomings, there is an urgent need for a silicon carbide abrasive with high hardness. Summary of the Invention

[0005] This invention provides a silicon carbide abrasive and its preparation method, which can provide a silicon carbide abrasive with high hardness.

[0006] In a first aspect, embodiments of the present invention provide a method for preparing silicon carbide abrasive, comprising:

[0007] Quartz sand, carbon source, and metallic aluminum are mixed evenly to obtain a mixture;

[0008] The mixture is calcined to obtain the silicon carbide abrasive.

[0009] In one possible design, the aluminum metal accounts for 0.5% to 5% of the mass of the mixture.

[0010] In one possible design, the carbon source includes petroleum tar.

[0011] In one possible design, the mass ratio of the quartz sand to the petroleum tar in the mixture is 1:(1-5).

[0012] In one possible design, the carbon source also includes wood chips.

[0013] In one possible design, the wood chips account for 2 to 8% of the mass of the mixture.

[0014] In one possible design, the calcination temperature is 1800–2000°C.

[0015] In one possible design, the calcination treatment time is 100-120 hours.

[0016] In one possible design, the calcination process is carried out in an inert gas.

[0017] The calcination process includes the following steps:

[0018] Calcination at 1000–2000 Pa for 60–80 h;

[0019] Calcination at 8–12 MPa for 20–40 h.

[0020] Secondly, embodiments of the present invention also provide a silicon carbide abrasive, prepared according to any of the methods described above.

[0021] Compared with the prior art, the present invention has at least the following beneficial effects:

[0022] In this embodiment, the main component of the silica sand is silicon dioxide. Silica and a carbon source can react at high temperatures to form silicon carbide. Silica sand and carbon sources are abundant and inexpensive, making them suitable for large-scale industrial production. During the reaction of silica and carbon source, aluminum atoms in the mixture replace some silicon atoms in the silicon carbide, resulting in aluminum-doped silicon carbide. The atomic radius of aluminum atoms is larger than that of silicon atoms. The substitution of silicon atoms by aluminum atoms reduces the interatomic gaps in the crystal lattice and generates compressive stress within the unit cell, thereby increasing the hardness of the resulting silicon carbide abrasive.

[0023] It should be noted that excessive aluminum doping of silicon carbide will damage the structure of silicon carbide and will instead lead to a decrease in the hardness of silicon carbide. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a flowchart of a method for preparing silicon carbide abrasive provided in an embodiment of the present invention. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0027] like Figure 1 As shown, this embodiment of the invention provides a method for preparing silicon carbide abrasive, comprising:

[0028] Quartz sand, carbon source, and metallic aluminum are mixed evenly to obtain a mixture;

[0029] The mixture was calcined to obtain silicon carbide abrasive.

[0030] In this embodiment, the main component of the silica sand is silicon dioxide. Silica and a carbon source can react at high temperatures to form silicon carbide. Silica sand and carbon sources are abundant and inexpensive, making them suitable for large-scale industrial production. During the reaction of silica and carbon source, aluminum atoms in the mixture replace some silicon atoms in the silicon carbide, resulting in aluminum-doped silicon carbide. The atomic radius of aluminum atoms is larger than that of silicon atoms. The substitution of silicon atoms by aluminum atoms reduces the interatomic gaps in the crystal lattice and generates compressive stress within the unit cell, thereby increasing the hardness of the resulting silicon carbide abrasive.

[0031] It should be noted that excessive aluminum doping of silicon carbide will damage the structure of silicon carbide and will instead lead to a decrease in the hardness of silicon carbide.

[0032] In some embodiments of the present invention, metallic aluminum accounts for 0.5% to 5% of the mass of the mixture (for example, it may be 0.5%, 0.8%, 1.0%, 1.2%, 1.4%, 1.8%, 2.0%, 2.2%, 2.4%, 2.6%, 2.8%, 3.0%, 3.2%, 3.4%, 3.6%, 3.8%, 4.0%, 4.2%, 4.4%, 4.6%, 4.8%, or 5.0%).

[0033] In this embodiment, too little aluminum doping (aluminum accounting for less than 0.5% of the mixture by mass) results in a low aluminum content in the silicon carbide crystals, thus failing to significantly improve the hardness of the silicon carbide abrasive. Excessive aluminum doping (aluminum accounting for more than 5% of the mixture by mass) damages the structure of the silicon carbide, leading to a decrease in its hardness.

[0034] In some embodiments of the present invention, the carbon source includes rock tar.

[0035] In this embodiment, in addition to providing a high-quality carbon source, stone tar also has the advantage of low cost. Furthermore, stone tar is liquid at room temperature and has a certain viscosity, which facilitates the coating of quartz sand to ensure uniform mixing.

[0036] It should be noted that when the mixture contains other solid substances, stone tar can also coat and mix all solid substances, including quartz sand, evenly.

[0037] In some embodiments of the present invention, the mass ratio of quartz sand to petroleum tar in the mixture is 1:(1 to 5) (for example, it can be 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5 or 1:5).

[0038] In this embodiment, to ensure a thorough reaction between the quartz sand and the stone tar, the quartz sand and stone tar need to be mixed evenly so that each grain of quartz sand is coated with stone tar. To achieve this effect, the mass ratio of quartz sand to stone tar needs to be limited to the aforementioned range, preferably 1:3. The reaction between the quartz sand and the carbon source is as follows:

[0039] SiO2 + 3C → SiC + 2CO

[0040] In some embodiments of the present invention, the carbon source also includes wood chips.

[0041] In this embodiment, adding sawdust to the mixture can adjust its permeability. This is because sawdust itself has a loose structure, and the evenly distributed sawdust in the mixture allows it to form a porous sintered body during calcination. Since gas is generated during the reaction of silicon dioxide and carbon to form silicon carbide, the porous sintered body allows the generated gas to escape in a timely manner, preventing the formation of pores and bubbles inside the resulting silicon carbide abrasive. At the same time, it also prevents gas from accumulating inside the sintered body and creating an internal pressure difference, which would otherwise make the formed silicon carbide abrasive prone to cracking.

[0042] In some embodiments of the present invention, the wood chips account for 2 to 8% of the mass of the mixture (e.g., 2%, 3%, 4%, 5%, 6%, 7% or 8%).

[0043] In this embodiment, extensive experimental verification has shown that the mass percentage of wood chips needs to be limited to between 2% and 8% of the mixture's mass. If the mass percentage of wood chips is less than 2%, the sintered body cannot form an effective porous structure. If the mass percentage of wood chips is higher than 8%, the sintered body will have too many pores, resulting in brittle silicon carbide abrasives that are prone to breakage.

[0044] In some embodiments of the present invention, the calcination temperature is 1800–2000°C (for example, it may be 1800°C, 1850°C, 1900°C, 1950°C or 2000°C).

[0045] In this embodiment, to allow the raw materials in the mixture to melt further at high temperatures and make the mixture more homogeneous, the calcination temperature needs to be limited to above 1800°C. To prevent the aluminum in the mixture from vaporizing and evaporating, the temperature needs to be controlled below 2000°C.

[0046] In some embodiments of the present invention, the calcination time is 100 to 120 hours (for example, it can be 100 hours, 105 hours, 110 hours, 115 hours or 120 hours).

[0047] In this embodiment, in order to allow the various raw materials in the mixture to react fully and improve the utilization rate of the raw materials, it is necessary to calcine for at least 100 to 120 hours.

[0048] In some embodiments of the present invention, the calcination process is carried out in an inert gas;

[0049] Calcination treatment includes the following steps:

[0050] Calcination treatment at 1000-2000 Pa (e.g., 1000 Pa, 1200 Pa, 1400 Pa, 1600 Pa, 1800 Pa or 2000 Pa) for 60-80 h (e.g., 60 h, 62 h, 64 h, 66 h, 68 h, 70 h, 72 h, 74 h, 76 h, 78 h or 80 h);

[0051] Calcination treatment at 8–12 MPa (e.g., 8 MPa, 9 MPa, 10 MPa, 11 MPa or 12 MPa) for 20–40 h (e.g., 20 h, 22 h, 24 h, 26 h, 28 h, 30 h, 32 h, 34 h, 36 h, 38 h or 40 h).

[0052] In this embodiment, the reaction needs to be carried out in an oxygen-free environment. Therefore, an inert gas needs to be introduced into the calcination furnace to protect the reactants from oxidation. To promptly remove the carbon monoxide generated during the initial stage of calcination, the reaction pressure needs to be limited to 1000–2000 Pa. As the reaction proceeds, the sintered body basically forms silicon carbide, but retains some porous structure. The porous structure affects the quality of the silicon carbide abrasive. Therefore, in the later stage of the reaction, the sintered body needs to be subjected to high-pressure treatment at 8–12 MPa to break down and compact the porous structure, further improving the density of the sintered body and thus further increasing its hardness.

[0053] This invention also provides a silicon carbide abrasive, prepared according to any of the methods described above.

[0054] To more clearly illustrate the technical solution and advantages of the present invention, a method for preparing silicon carbide abrasive is described in detail below through several embodiments.

[0055] Example 1

[0056] Quartz sand, stone tar, and metallic aluminum are mixed evenly to obtain a mixture; wherein the mass ratio of quartz sand to stone tar is 1:1, and metallic aluminum accounts for 0.5% of the mass of the mixture;

[0057] The mixture was calcined to obtain silicon carbide abrasive; the calcination temperature was 1800℃, first calcined at 1000Pa for 60h, and then calcined at 8MPa for 40h.

[0058] Example 2

[0059] Example 2 is basically the same as Example 1, except that the mass ratio of quartz sand and stone tar is 1:3, and the mass of metallic aluminum accounts for 3% of the mixture. It is first calcined at 1500 Pa for 75 h, and then calcined at 10 MPa for 35 h. The calcination temperature is 1900 °C.

[0060] Example 3

[0061] Example 3 is basically the same as Example 1, except that the mass ratio of quartz sand and stone tar is 1:5, and the mass of metallic aluminum accounts for 5% of the mixture. It is first calcined at 2000 Pa for 80 h, and then calcined at 12 MPa for 40 h. The calcination temperature is 2000℃.

[0062] Example 4

[0063] Example 4 is basically the same as Example 1, except that the mixture also includes 2% by weight of wood chips.

[0064] Example 5

[0065] Example 5 is basically the same as Example 1, except that the mixture also includes 5% by weight of wood chips.

[0066] Example 6

[0067] Example 6 is basically the same as Example 1, except that the mixture also includes 8% by weight of wood chips.

[0068] Example 7

[0069] Example 7 is basically the same as Example 1, except that it is calcined at normal pressure for 100 hours.

[0070] Comparative Example 1

[0071] Comparative Example 1 is basically the same as Example 2, except that no metallic aluminum is added to the mixture.

[0072] Comparative Example 2

[0073] Comparative Example 2 is basically the same as Example 2, except that the metallic aluminum in the mixture accounts for 0.3% of the mass of the mixture.

[0074] Comparative Example 3

[0075] Comparative Example 3 is basically the same as Example 2, except that the metallic aluminum in the mixture accounts for 8% of the mass of the mixture.

[0076] Comparative Example 4

[0077] Comparative Example 4 is basically the same as Example 5, except that the mass percentage of sawdust in the mixture is 1%.

[0078] Comparative Example 5

[0079] Comparative Example 5 is basically the same as Example 5, except that the mass percentage of sawdust in the mixture is 10%.

[0080] Comparative Example 6

[0081] Comparative Example 6 is basically the same as Example 2, except that the calcination temperature is 1600°C.

[0082] Comparative Example 7

[0083] Comparative Example 7 is basically the same as Example 2, except that the calcination temperature is 2200℃.

[0084] Hardness tests were performed on the products of Examples 1-7 and Comparative Examples 1-3, and the results are shown in the table below:

[0085] hardness Polishing efficiency in 1 hour Polishing efficiency in 4 hours Example 1 30.2 GPa 0.76μm / min 0.72μm / min Example 2 31.3 GPa 0.77μm / min 0.73 μm / min Example 3 30.9 GPa 0.75μm / min 0.72μm / min Example 4 33.9 GPa 0.79μm / min 0.76μm / min Example 5 34.4 GPa 0.8μm / min 0.75μm / min Example 6 34.2 GPa 0.78μm / min 0.72μm / min Example 7 29.8 GPa 0.69μm / min 0.61 μm / min Comparative Example 1 27.7 GPa 0.64μm / min 0.57μm / min Comparative Example 2 28.1 GPa 0.66μm / min 0.58μm / min Comparative Example 3 27.9 GPa 0.67μm / min 0.53 μm / min

[0086] The products obtained from Comparative Examples 4 and 5 were sliced ​​and observed under a microscope. Large air bubbles were observed in the product of Comparative Example 4, while residual sawdust structure was observed in the product of Comparative Example 5.

[0087] The products of Comparative Examples 6 and 7 were crushed to obtain powders, and the crystalline phase composition of the powders obtained from Comparative Examples 6 and 7 was analyzed. The silicon carbide phase accounted for a small proportion in the product of Comparative Example 6; the aluminum content in the product of Comparative Example 7 was extremely low, less than 0.1%.

[0088] In this invention, the hardness testing method is as follows:

[0089] Using a German KB5 hardness tester, the load pressure F was set to 0.49, 0.98, 1.47, 1.96, 2.45, 2.94, 3.43, 3.92, 4.41 and 4.9 N respectively. The set load was applied to the sample with a diamond indenter and held for 14 seconds. The diagonal lengths d1 and d2 of the indentation were measured. Five tests were performed under each load, and the Vickers hardness of the material was calculated.

[0090] The formula for calculating Vickers hardness is as follows:

[0091]

[0092] Among them, H v d1 and d2 are the hardness, d1 and d2 are the diagonal lengths of the indentation, and F is the load pressure.

[0093] The polishing efficiency is calculated as follows:

[0094] Twelve 4-inch sapphire wafers were selected and divided into two groups of six. The polishing removal efficiency was calculated. The formula for calculating the wafer removal efficiency is as follows:

[0095] MRR=Δm / (ρπr 2 t)

[0096] Where MRR is the removal efficiency, m is the mass, ρ is the density, r is the wafer radius, and t is the time.

[0097] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method of making a silicon carbide abrasive, characterized by, The application relates to a preparation method of a silicon carbide abrasive material. The quartz sand, a carbon source and aluminum are uniformly mixed to obtain a mixture; The mixture is subjected to calcination treatment to obtain the silicon carbide abrasive material; The carbon source comprises stone tar, the mass ratio of the quartz sand to the stone tar in the mixture is 1: (1-5), and the carbon source further comprises wood chips, the mass of the wood chips accounts for 2-8% of the mass of the mixture; The temperature of the calcination treatment is 1800-2000 DEG C; The time of the calcination treatment is 100-120 h; The calcination treatment is carried out in an inert gas; The calcination treatment comprises the following steps: The calcination treatment is carried out at 1000-2000 Pa for 60-80 h; The calcination treatment is carried out at 8-12 MPa for 20-40 h; The mass of the aluminum accounts for 0.5-5% of the mass of the mixture.

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