SiC whisker toughened Si3N4Ceramic pneumatic motor blade, preparation method and pneumatic motor
1. SiC whisker toughened Si3N4The ceramic pneumatic motor blade is characterized in that the raw materials consist of the following components: si3N4Ceramic base powder, SiC whisker, Y2O3，A12O3And epoxy resins; with Si3N4The mass of the ceramic-based powder is 8-12 wt% of SiC whisker and Y2O35-7 wt%, A12O3Accounting for 2-4 wt%, and the amount of the epoxy resin is 30-40 vol% of the composite powder.
2. The SiC whisker toughened Si of claim 13N4A ceramic air motor blade characterized in that the outermost layer of the composite powder is coated with an epoxy resin by a solvent evaporation method.
3. The SiC whisker toughened Si of claim 13N4Ceramic pneumatic motor blade, characterized in that said Si3N4The ceramic base powder is beta-Si3N4，D50＝3-10μm。
4. The SiC whisker toughened Si of claim 13N4The ceramic pneumatic motor blade is characterized in that the SiC crystal whisker has the diameter of 0.1-1.0 mu m and the length-diameter ratio>20。
5. The SiC whisker toughened Si of claim 13N4The ceramic pneumatic motor blade is characterized in that the epoxy resin is bisphenol A type epoxy resin.
6. The SiC whisker toughened Si of any one of claims 1 to 53N4The preparation method of the ceramic pneumatic motor blade is characterized by comprising the following steps of:
s1, taking the components in proportion, and mixing Si3N4Ceramic base powder, SiC whisker, Y2O3，A12O3Uniformly mixing, coating the epoxy resin by a solvent evaporation method to prepare Si3N4/SiC(w)Epoxy resin composite powder;
s2, obtaining a biscuit by SLS according to preset molding parameters for the composite powder;
s3, vacuumizing the biscuit and carrying out cold isostatic pressing treatment;
and S4, removing the glue and sintering at high temperature to obtain the product.
7. The SiC whisker toughened Si of claim 63N4The preparation method of the ceramic pneumatic motor blade is characterized in that in step S3, the pressure maintaining parameters of the cold isostatic pressing are as follows: 200 MPa, pressure maintaining for 1-10min, pressure raising rate of 1-3MPa/s and pressure relieving rate of 0.5-2 MPa/s.
8. The SiC whisker toughened Si of claim 63N4The preparation method of the ceramic pneumatic motor blade is characterized in that in the step S4, when the glue is discharged, the temperature is raised to 550-650 ℃ from room temperature at the speed of 1-2 ℃/min, and the temperature is kept for 1-2h and then the ceramic pneumatic motor blade is cooled to a greenhouse along with a furnace.
9. The SiC whisker toughened Si of claim 63N4The preparation method of the ceramic pneumatic motor blade is characterized in that in the step S4, during high-temperature sintering, the temperature is raised to 1600-2000 ℃ from room temperature at the speed of 2-8 ℃/min under the nitrogen pressure of 0.1-0.3MPa, and the temperature is kept for 2-3h and then the ceramic pneumatic motor blade is cooled along with the furnace.
10. An air motor comprising a ceramic blade, wherein the ceramic blade is the SiC whisker-toughened Si according to any one of claims 1 to 53N4Ceramic air motor blades.
Background
A pneumatic motor, also known as a pneumatic motor, is a device that converts the pressure energy of compressed air into rotational mechanical energy, and is generally used as a rotary power source for more complex devices or machines. The pneumatic motors are classified by structure: vane-type pneumatic motors, piston-type pneumatic motors, compact vane-type pneumatic motors, compact piston-type pneumatic motors. Compared with the motor which has the same function as the pneumatic motor, the pneumatic motor is characterized by light outer shell and convenient transportation. The pneumatic motor also has higher starting torque and can be directly started with load. When the overload occurs, the motor only reduces or stops the rotating speed, and when the overload is relieved, the motor can immediately run normally again without generating faults such as machine part damage and the like. And because the working medium is air, the material is easy to obtain, and the discharged waste gas does not influence the environment.
The light-load vane type pneumatic motor is mostly made of metal, and because the metal vanes are sealed with the motor stator through pressure, the vanes need to overcome certain friction force to push the motor rotor to rotate, and the long-term use can cause metal abrasion, and the light-load vane type pneumatic motor needs frequent maintenance and has short service life. In addition, the compressed air in the use environment contains water vapor and oil mist, and metal parts are easy to rust. Some pneumatic motors have low blade strength, poor toughness, difficult blowout during starting, poor starting performance and low working efficiency.
Disclosure of Invention
The invention aims to solve the technical problems that the existing light-load type pneumatic motor blade is made of metal, and the problems of low strength, poor toughness, short service life and the like are easily caused on the premise of ensuring light load.
In order to solve the above problems, the present invention proposes the following technical solutions:
in a first aspect, the present inventionProvides SiC whisker toughened Si3N4The ceramic pneumatic motor blade is prepared from the following raw materials: si3N4Ceramic base powder, SiC whisker, Y2O3，A12O3And epoxy resins; with Si3N4The mass of the ceramic-based powder is 8-12 wt% of SiC whisker and Y2O35-7 wt%, A12O3Accounting for 2-4 wt%, and the amount of the epoxy resin is 30-40 vol% of the composite powder.
The further technical scheme is that the outermost layer of the composite powder is coated with epoxy resin by a solvent evaporation method.
The further technical scheme is that the Si is3N4The ceramic base powder is beta-Si3N4，D503-10 μm, more preferably, D50＝5-8μm。
The further technical proposal is that the diameter of the SiC whisker is 0.1-1.0 μm, and the length-diameter ratio is more than 20.
The further technical scheme is that the epoxy resin is bisphenol A type epoxy resin.
The invention also provides the SiC whisker toughened Si3N4The preparation method of the ceramic pneumatic motor blade comprises the following steps:
s1, taking the components in proportion, and mixing Si3N4Ceramic base powder, SiC whisker, Y2O3，A12O3Uniformly mixing, coating the epoxy resin by a solvent evaporation method to prepare Si3N4/SiC(w)Epoxy resin composite powder;
s2, performing SLS (selective laser sintering) molding on the composite powder according to preset molding parameters to obtain a biscuit;
s3, vacuumizing the biscuit and carrying out cold isostatic pressing treatment;
and S4, removing the glue and sintering at high temperature to obtain the product.
SLS (Selective Laser Sintering) is a technique for Sintering a powder material into a solid article using a high-energy beam Laser. The principle is that a three-dimensional model of a product is divided into a plurality of layers of two-dimensional slices, then powder materials in the slice area are selectively sintered by laser, and then a layer of powder materials is laid for continuous sintering after the sintering is finished. And accumulating layer by layer until the three-dimensional part is finished.
As shown in FIG. 1, a process flow diagram for SLS/CIP integration. The invention adopts preset SLS forming parameters, the powder roller is used for paving the powder on the workbench, then the computer is used for controlling the laser to selectively scan the paved powder layer, and the bonding agent in the scanned powder is melted and flowed to promote the powder particles to be bonded into corresponding shapes. The upper and lower 2 layers are also bonded due to the heat transfer effect, then the powder cylinder is lifted, and the workbench is lowered by 1 layered layer thickness height. And repeating the process until the part is completely molded to obtain a biscuit.
And then covering the biscuit formed by printing with a sheath, pumping out air in the sheath to enable the sheath to be tightly attached to the sample, and putting the sample into a cold isostatic press for Cold Isostatic Pressing (CIP).
The inventors have found that the CIP process can reduce the number of pores in the green body as well as the pore size. The density and the strength of the biscuit body after CIP treatment are improved, and the later-stage sintering is facilitated.
Therefore, the preparation method of the invention has the following advantages after CIP treatment: after CIP treatment, the performance of the biscuit is obviously improved. The porosity of the biscuit is reduced from 36.73% to 29.90%, and the bending strength is increased from 3.16MPa to 6.11MPa, so that the compactness and the bending strength of the product can be obviously improved.
The further technical scheme is that in step S3, the pressure maintaining parameters of the cold isostatic pressing are as follows: 200 MPa, pressure maintaining for 1-10min, pressure raising rate of 1-3MPa/s and pressure relieving rate of 0.5-2 MPa/s.
More preferably, the dwell parameters are: keeping the pressure for 5min at 250MPa, wherein the pressure increasing rate is 2MPa/s, and the pressure relieving rate is 1 MPa/s.
The further technical scheme is that in the step S4, when the glue is discharged, the temperature is raised to 550-650 ℃ from room temperature at the speed of 1-2 ℃/min, and the temperature is kept for 1-2h and then the mixture is cooled to the greenhouse along with the furnace.
More preferably, the glue discharging process is that the temperature is raised to 600 ℃ from room temperature at the speed of 1.5 ℃/min, and the temperature is kept for 1.5h and then the mixture is cooled to a greenhouse along with a furnace.
The further technical scheme is that in the step S4, during high-temperature sintering, the temperature is raised from room temperature to 1600-2000 ℃ at the speed of 2-8 ℃/min under the nitrogen pressure of 0.1-0.3MPa, and the temperature is kept for 2-3h and then cooled along with the furnace.
More preferably, the sample is sintered at high temperature by adopting an atmosphere sintering furnace, the sintering process is that the temperature is raised to 1800 ℃ from room temperature at 5 ℃/min under the nitrogen pressure of 0.15MPa, and the temperature is kept for 2.5h and then the sample is cooled along with the furnace.
In a second aspect, the invention provides a pneumatic motor comprising a ceramic blade, wherein the ceramic blade is the SiC whisker toughened Si3N4Ceramic air motor blades.
Compared with the prior art, the invention can achieve the following technical effects:
the invention adopts Si3N4The ceramic material replaces the existing metal material to manufacture the pneumatic motor blade, the density is lower, the total weight of the motor product can be fully reduced, and the pneumatic motor blade has the characteristic of lighter load; the ceramic blade has good thermal shock resistance stability, and the wear resistance and corrosion resistance performance obviously surpass those of the existing metal materials; the SiC crystal whiskers are added into the ceramic pneumatic motor blade to toughen and modify the material, so that the ceramic blade has the characteristics of bending resistance and more compact texture; effectively improve the defects of low strength and poor toughness of the blades in the existing pneumatic motor and prolong the service life of the blades.
The preparation method provided by the invention adopts the Selective Laser Sintering (SLS) technology to prepare Si3N4The ceramic blade biscuit is used for quickly forming a ceramic component with a complex shape.
Drawings
FIG. 1 is a schematic view of a SLS/CIP integrated process flow of the present invention;
fig. 2 is a schematic structural diagram of an air motor according to an embodiment of the present invention.
Detailed Description
The technical solutions in the examples will be clearly and completely described below. It is apparent that the embodiments to be described below are only a part of the embodiments of the present invention, and not all of them. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1
The invention provides SiC whisker toughened Si3N4The ceramic pneumatic motor blade is prepared from the following raw materials: si3N4Ceramic base powder, SiC whisker, Y2O3，A12O3And epoxy resins; with Si3N4The ceramic base powder is used as a raw material, SiC crystal whisker accounting for 10 wt% of the mass of the raw material and Y accounting for 6 wt% of the mass of the raw material are added2O3，4wt％A12O3The amount of the epoxy resin was 35 vol% based on the total volume of the composite powder.
Si3N4The ceramic base powder is beta-Si3N4，D50＝6.59μm。
The diameter of the SiC crystal whisker is 0.1-1.0 μm, and the length-diameter ratio is more than 20.
The epoxy resin described in this example is bisphenol a type epoxy resin, the molecular structure of the epoxy resin contains hydroxyl and ether bond, and new-OH and-O-are further generated during the curing process, so that the cured product has high cohesive force and adhesive force.
In one embodiment, the epoxy resin is type E12 and has an epoxy value of 0.10 to 0.18.
The embodiment of the invention also provides the SiC whisker toughened Si3N4The preparation method of the ceramic pneumatic motor blade comprises the following steps:
s1, taking the components in proportion, and mixing Si3N4Ceramic base powder, SiC whisker, Y2O3，A12O3Uniformly mixing, coating the epoxy resin by a solvent evaporation method to prepare Si3N4/SiC(w)a/E12 composite powder;
s2, performing SLS (selective laser sintering) molding on the composite powder according to preset molding parameters to obtain a biscuit;
s3, vacuumizing the biscuit, and performing cold isostatic pressing treatment, wherein the pressure maintaining parameters are as follows: keeping the pressure for 5min at 250MPa, wherein the pressure increasing rate is 2MPa/s, and the pressure relieving rate is 1 MPa/s;
s4, removing glue and sintering at high temperature to obtain a product;
specifically, the glue discharging process comprises the steps of heating to 600 ℃ from room temperature at a speed of 1.5 ℃/min, preserving heat for 1.5h, and then cooling to a greenhouse along with a furnace; and during high-temperature sintering, a sample is sintered at high temperature by adopting an atmosphere sintering furnace, the sintering process is that the temperature is raised to 1800 ℃ from room temperature at 5 ℃/min under the nitrogen pressure of 0.15MPa, and the temperature is kept for 2.5h and then the sample is cooled along with the furnace.
The SiC whisker toughened Si obtained in the example3N4The porosity of the ceramic pneumatic motor blade after biscuit sintering is 29.9 percent, and the bending strength is 6.11 MPa.
Example 2
The invention provides SiC whisker toughened Si3N4The ceramic pneumatic motor blade is prepared from the following raw materials: si3N4Ceramic base powder, SiC whisker, Y2O3，A12O3And epoxy resins; with Si3N4Using ceramic base powder as raw material, adding SiC crystal whisker accounting for 9 wt% of the mass of the raw material and Y accounting for 7 wt% of the mass of the raw material2O3，3wt％A12O3The amount of the epoxy resin was 38 vol% based on the total volume of the composite powder.
Si3N4The ceramic base powder is beta-Si3N4，D50＝8.0μm。
The diameter of the SiC crystal whisker is 0.1-1.0 μm, and the length-diameter ratio is more than 20.
The epoxy resin of this example has a type E12 and an epoxy value of 0.10-0.18.
The embodiment of the invention also provides the SiC whisker toughened Si3N4The preparation method of the ceramic pneumatic motor blade comprises the following steps:
s1, taking the components in proportion, and mixing Si3N4Ceramic base powder, SiC whisker, Y2O3，A12O3Uniformly mixing, coating the epoxy resin by a solvent evaporation method to prepare Si3N4/SiC(w)a/E12 composite powder;
s2, forming the composite powder through SLS according to preset forming parameters to obtain a biscuit;
s3, vacuumizing the biscuit, and performing cold isostatic pressing treatment, wherein the pressure maintaining parameters are as follows: keeping the pressure for 5min at 280MPa, wherein the pressure increasing rate is 2MPa/s, and the pressure relieving rate is 1 MPa/s;
s4, removing glue and sintering at high temperature to obtain a product;
specifically, the glue discharging process comprises the steps of heating to 620 ℃ from room temperature at a speed of 1.5 ℃/min, preserving heat for 1.5h, and then cooling to a greenhouse along with a furnace; and during high-temperature sintering, a sample is sintered at high temperature by adopting an atmosphere sintering furnace, the sintering process is that the temperature is raised to 1800 ℃ from room temperature at 5 ℃/min under the nitrogen pressure of 0.15MPa, and the temperature is kept for 2.5h and then the sample is cooled along with the furnace.
Example 3
The invention provides SiC whisker toughened Si3N4The ceramic pneumatic motor blade is prepared from the following raw materials: si3N4Ceramic base powder, SiC whisker, Y2O3，A12O3And epoxy resins; with Si3N4Using ceramic base powder as raw material, adding SiC crystal whisker accounting for 11 wt% of the mass of the raw material and Y accounting for 7 wt% of the mass of the raw material2O3，3wt％A12O3The amount of the epoxy resin was 34 vol% based on the total volume of the composite powder.
Si3N4The ceramic base powder is beta-Si3N4，D50＝4.0μm。
The diameter of the SiC crystal whisker is 0.1-1.0 μm, and the length-diameter ratio is more than 20.
The epoxy resin of this example has a type E12 and an epoxy value of 0.10-0.18.
The embodiment of the invention also provides the SiC whisker toughened Si3N4The preparation method of the ceramic pneumatic motor blade comprises the following steps:
s1, taking the components in proportion, and mixing Si3N4Ceramic base powder, SiC whisker, Y2O3，A12O3Uniformly mixing, coating the epoxy resin by a solvent evaporation method to prepare Si3N4/SiC(w)a/E12 composite powder;
s2, forming the composite powder through SLS according to preset forming parameters to obtain a biscuit;
s3, vacuumizing the biscuit, and performing cold isostatic pressing treatment, wherein the pressure maintaining parameters are as follows: maintaining the pressure for 5min at 240MPa, the pressure increasing rate is 2MPa/s, and the pressure relieving rate is 1 MPa/s;
s4, removing glue and sintering at high temperature to obtain a product;
specifically, the glue discharging process comprises the steps of heating to 580 ℃ from room temperature at a speed of 1.5 ℃/min, preserving heat for 2 hours, and then cooling to a greenhouse along with a furnace; and during high-temperature sintering, a sample is sintered at high temperature by adopting an atmosphere sintering furnace, the sintering process is that the temperature is increased from room temperature to 1900 ℃ at the speed of 5 ℃/min under the nitrogen pressure of 0.15MPa, and the temperature is preserved for 2h and then the sample is cooled along with the furnace.
Comparative example
The comparative example is different from example 1 in that the cold isostatic pressing process of step S3 is not included in the preparation method.
The green compact of the comparative example had a porosity of 36.73% after sintering and a flexural strength of 3.16 MPa.
Referring to fig. 2, an embodiment of the present invention further provides an air motor, including a ceramic blade, where the ceramic blade is the SiC whisker-toughened Si described in any one of embodiments 1 to 3 above3N4Ceramic air motor blades.
It is understood that the pneumatic motor is a prime mover using compressed air as a working medium, and is a power device that converts pressure energy into mechanical energy by using the expansion action of compressed air. As shown in fig. 2, a bi-directional vane-type pneumatic motor is illustrated. The working principle is that compressed air is input from the hole A, a small part of the air enters the bottoms of the blades 3 (not shown in the figure) through the grooves of the sealing covers at the two ends of the stator 2, the blades 3 are pushed out, the blades 3 are attached to the inner wall of the stator 2, and most of the compressed air enters corresponding sealing spaces and acts on the two blades 3. Because the two blades 3 have different extending lengths, a torque difference is generated, so that the blades 3 and the rotor 1 rotate in the counterclockwise direction, and the gas after work is discharged from the holes B, C on the stator 2.
If the direction of the compressed air input is changed (i.e., compressed air enters through hole B and exits through hole a), the direction of rotation of the rotor may be changed.
The light-load vane type pneumatic motor mainly comprises a rotor 1, a stator 2, vanes 3, a shell and the like, wherein A is a compressed air blowing inlet, B is an exhaust port, and C is a secondary exhaust port. In order to ensure that the vanes extend outward and reliably seal with the inner surface of the stator, the roots of the vanes 3 are supplied with compressed air and provided with self-aligning springs. Compressed air is input from the air inlet A and acts on the extending surfaces of the blades on the two sides of the working cavity. Because the rotor 1 and the stator 2 are eccentrically installed, the extending lengths of the two blades 3 are different, and the working areas of the air pressure acting on the blades 3 are different, so that the air pressure generates torque difference on the blades 3 at the two sides to push the rotor to rotate anticlockwise. The gas after work is taken into the exhaust cavity and discharged from the outlet C, and the residual gas is discharged from the outlet B. If the input direction of the compressed air is changed, the rotation direction of the rotor can be changed.
Because the blade 3 is always tightly attached to the inner wall of the cylinder body, the root of the blade 3 is pressed by compressed air and a spring, and therefore the blade 3 is required to have higher antifriction property, wear resistance and bending strength.
The SiC whisker toughened Si provided by the invention3N4Ceramic pneumatic motor blade of Si3N4The motor is made of ceramic materials, has lower density, can fully reduce the total weight of motor products, and has the characteristic of lighter load; the SiC crystal whiskers are added to toughen and modify the material, so that the ceramic blade has the characteristics of higher bending resistance, more compact texture and higher wear resistance; effectively improve the defects of low strength and poor toughness of the blades in the existing pneumatic motor and prolong the service life of the blades.
In the above embodiments, the descriptions of the respective embodiments have respective emphasis, and for parts that are not described in detail in a certain embodiment, reference may be made to related descriptions of other embodiments.
While the invention has been described with reference to specific embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
