CN112548344A

CN112548344A - Efficient clean thinning method applied to silicon carbide ceramic

Info

Publication number: CN112548344A
Application number: CN202011295353.0A
Authority: CN
Inventors: 李晓鹏; 支新涛; 王大森; 袁松梅; 王克鸿
Original assignee: Nanjing University of Science and Technology
Current assignee: Nanjing University of Science and Technology
Priority date: 2020-11-18
Filing date: 2020-11-18
Publication date: 2021-03-26

Abstract

The invention relates to a high-efficiency clean thinning method applied to silicon carbide ceramics. The method is characterized in that laser irradiation treatment is carried out on a fixed silicon carbide workpiece, the characteristics of short pulse laser, high energy and short action time are utilized, the silicon carbide ceramic is induced to generate coulomb explosion in an action area, the ceramic in the action area is subjected to plasma and gasification, and the thinning effect is realized. The method adopts pulse laser as an energy source, is safe and clean, has controllable thinning position, small residual stress and unlimited thinning shape. The invention is suitable for silicon carbide products with the surface needing to be thinned or locally processed.

Description

Efficient clean thinning method applied to silicon carbide ceramic

Technical Field

The invention relates to the technical field of silicon carbide material reduction processing, in particular to a high-efficiency clean thinning method applied to silicon carbide ceramics.

Background

The SiC material has a series of advantages of good physical and chemical properties, such as stable chemical properties, small thermal expansion coefficient, corrosion resistance, abrasion resistance, high strength, high hardness and the like, so the SiC material has wide application prospects in the fields of mechatronics, composite materials, aerospace and the like. For example, in the manufacture of jet and automotive engines, there are a large number of micro-porous structures; the material becomes the preferred material for preparing the reflector and has been applied in a certain range; meanwhile, in the field of chip manufacturing, a large number of processing tasks of micro structures, such as through holes or non-through holes, are also faced. Although many ceramic materials are used for the structure, SiC is the preferred material due to the excellent performance of SiC. But due to the particularity of the crystal structure and high hardness, SiC is a recognized typical difficult-to-machine material.

For the material reduction processing of silicon carbide, the grinding means is mainly adopted for processing and removing at present, but the problems of quick abrasion of a grinding wheel, environmental pollution of cutting fluid, limited processing area, low processing efficiency and the like exist. Although the magnetorheological processing has higher surface precision, the problems of low processing efficiency, pollution of cutting fluid and the like exist. Although ion beam machining has high accuracy, the efficiency of removing material is low, about 1.9mm³Min, cannot meet the processing of a large number of elements.

Therefore, the realization of efficient, pollution-free, local precision machining of silicon carbide workpieces has become a key technology of high-precision equipment.

Disclosure of Invention

The invention aims to solve the defects of the prior art and provides a high-efficiency clean thinning method applied to silicon carbide ceramics. The method adopts clean high-power laser irradiation to realize local thinning of the silicon carbide workpiece.

The technical scheme adopted by the invention for solving the technical problems is as follows:

the efficient cleaning and thinning method applied to the silicon carbide ceramic comprises the steps of pumping, fixing, adjusting laser parameters, drawing a scanning path and adjusting a processing technological procedure.

The efficient clean thinning method of the silicon carbide comprises the following specific steps:

step 1, placing a silicon carbide workpiece on a laser workbench, wherein the part to be processed corresponds to the laser direction.

And 2, turning on the vacuum pump to fix the workpiece on the workbench.

And 3, drawing a processing track graph and leading the processing track graph into a laser control system.

And 4, opening the air pump.

And 5, adjusting laser parameters, setting a processing process rule, and enabling the focus to move according to the scanning track pattern to realize material thinning of the preset area.

The laser in the invention refers to nanosecond, picosecond and femtosecond pulse width level infrared laser.

In the invention, the laser workbench in the step 2 is connected with the vacuum pump in the step 3, so that the vacuum fixing and adsorption of the workpiece are realized.

In the invention, the trace graph is scanned in the step 3, and drawing is needed according to the processing part and the shape.

The laser parameters in step 5 of the present invention include pulse width, frequency and power.

The processing process rule in the step 5 of the invention comprises defocusing amount, scanning speed, repeated scanning times and feeding depth.

Specifically, the pulse width of the laser is 300 fs-100 ns, the wavelength is 800 nm-1064 nm, the power is 2W-40W, the frequency is 0.2 MHz-1 MHz, the defocusing amount is-0.5 mm-3 mm, and the scanning speed is 100 mm/s-1000 mm/s;

the processing track is required to meet the condition that the overlapping rate of light spots is 50-90 percent, and the distance between adjacent tracks is 0.1-0.6 times of the diameter of the light spots; the processing technical procedure comprises the following steps: repeating for 1-50 times; the feeding amount is 0.01-0.3 mm.

The principle and basis of the invention are as follows: the short pulse laser has very high instantaneous power, the electromagnetic field intensity at the focus is far greater than the coulomb field intensity of atoms to electrons, the electrons are instantly changed into free electrons to form plasma, the plasma absorbs the laser to explode under the action of subsequent laser, the material is removed, and the sputtered material is sucked away by the air suction pump.

Compared with the prior art, the invention has the following remarkable advantages:

1. the silicon carbide material is thinned by adopting short pulse laser, so that a heat affected area is small;

2. the silicon carbide material is thinned by short pulse laser, so that the material at a key position can be removed, and the overall performance is improved;

3. the silicon carbide material is thinned by adopting short pulse laser, so that the surface thinning of a complex shape can be realized, and the application range of the silicon carbide material is expanded;

4. the silicon carbide material is thinned by adopting short pulse laser, and the cutting fluid is not required to be used for cooling and lubricating, so that the environment is protected, and the cost is reduced.

Drawings

FIG. 1 is a schematic diagram of the efficient and clean thinning method of silicon carbide according to the present invention.

FIG. 2 is a schematic diagram of a scanning track of the efficient and clean thinning method for silicon carbide according to the present invention.

Fig. 3 is a topography after laser machining.

In the figure, 1 is a vacuum pump, 2 is an air pump, 3 is a pulse laser control system, 4 is laser, 5 is a silicon carbide workpiece, and 6 is a workbench.

Detailed Description

The invention is further described below with reference to the accompanying drawings:

example 1

And carrying out high-efficiency clean thinning processing on the vapor deposition silicon carbide by using pulse laser. Placing a silicon carbide workpiece 5 on a workbench 6, starting a vacuum pump 1 to enable the silicon carbide workpiece 5 to be adsorbed and fixed on the workbench 6, then adjusting a pulse laser control system 3 to enable the focus of laser 4 to be positioned on the upper surface of the silicon carbide workpiece, starting an air suction pump 2, adjusting laser parameters to 35W, the pulse width to 300fs, the repetition frequency to 1MHz, the scanning speed to 300mm/s and the track interval to 0.01mm, and adopting 25 times in the processing process rules. Scanning is performed by irradiation with the S-shaped track 1 in fig. 2. The removal of the silicon carbide workpiece is realized, and meanwhile, the time for scanning is recorded. The thinned area is detected and calculated by using a confocal microscope, and the material removal rate is about 6.8mm³/min。

The efficient and clean thinning method for the silicon carbide is applicable to reactive sintering of the silicon carbide, hot-pressing sintering of the silicon carbide and chemical vapor deposition of the silicon carbide.

The method adopts nanosecond, picosecond and femtosecond laser to irradiate the silicon carbide surface, and further adjusts the removal effect of the silicon carbide surface by changing parameters such as laser power, defocusing amount, scanning speed, scanning track, repetition times and the like. By adjusting relevant parameters of pulse laser, laser energy is focused on the surface of silicon carbide, a strong electric field is formed by utilizing the high energy density of short pulses, the nonlinear absorption of materials at a focus is directly caused, heat cannot be diffused in time in a very short time, plasma is formed, the plasma is exploded after absorbing the laser energy at the back, and explosives are pumped away by an air pump, so that the efficient clean thinning of the silicon carbide is realized.

The efficient and clean thinning method for the silicon carbide can obtain higher material removal rate and better surface quality. The scanning method adopted in the process steps of the efficient and clean silicon carbide thinning method is simple and reliable, and the thinning position is accurate and controllable. By changing the trajectory, local thinning of the irregular plane can be easily achieved. The application range of the silicon carbide material is enlarged, the product cost is reduced, and the environmental pollution is reduced.

Claims

1. The efficient cleaning and thinning method for the silicon carbide ceramic is characterized in that laser irradiation is carried out on the fixed silicon carbide surface, the laser energy density is higher than the damage threshold of the silicon carbide, high-energy laser induces the silicon carbide to form plasma by controlling laser parameters and according to a scanning path, the plasma explodes under the action of the laser energy to remove materials, and the materials directly leave the surface of a sample piece under the action of an air pump.

2. The method for efficient clean thinning of silicon carbide as claimed in claim 1 wherein said laser comprises a nanosecond laser, a picosecond laser or a femtosecond laser.

3. The efficient and clean thinning method for silicon carbide according to claim 1, characterized in that the fixing is performed by vacuum adsorption.

4. The efficient clean thinning method for silicon carbide according to any one of claims 1 to 3, characterized by comprising the steps of:

step 1, placing a silicon carbide workpiece on a workbench, wherein a processing part is opposite to the direction of a laser source;

step 2, starting a vacuum pump to realize workpiece adsorption;

step 3, drawing a processing path and leading the processing path into a laser control system;

step 4, opening an air pump;

and 5, adjusting laser parameters, enabling the focus to move according to the drawn scanning path, setting a processing technological procedure, and realizing efficient and clean processing of the area to be processed.

5. The efficient and clean thinning method for silicon carbide according to claim 4, characterized in that in the step 5, the irradiation adopts laser parameters including: the pulse width of the laser is 300 fs-100 ns, the wavelength is 800 nm-1064 nm, the power is 2W-40W, the frequency is 0.2 MHz-1 MHz, the defocusing amount is-0.5 mm-3 mm, and the scanning speed is 100 mm/s-1000 mm/s.

6. The efficient and clean thinning method for silicon carbide according to claim 4, wherein in the step 5, the track pattern adopted by irradiation comprises S-shaped tracks and parallel tracks.

7. The efficient and clean silicon carbide thinning method according to claim 6, characterized in that the processing tracks have a spot overlap ratio of 50% -90%, and the distance between adjacent tracks is 0.1-0.6 times the diameter of a spot; the processing technical procedure comprises the following steps: repeating for 1-50 times; the feeding amount is 0.01-0.3 mm.