CN113956609B - Wear-resistant antistatic polyether ether ketone based composite material and preparation method and application thereof - Google Patents
Wear-resistant antistatic polyether ether ketone based composite material and preparation method and application thereof Download PDFInfo
- Publication number
- CN113956609B CN113956609B CN202111416945.8A CN202111416945A CN113956609B CN 113956609 B CN113956609 B CN 113956609B CN 202111416945 A CN202111416945 A CN 202111416945A CN 113956609 B CN113956609 B CN 113956609B
- Authority
- CN
- China
- Prior art keywords
- composite material
- based composite
- wear
- ether ketone
- preparation
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K7/00—Use of ingredients characterised by shape
- C08K7/02—Fibres or whiskers
- C08K7/04—Fibres or whiskers inorganic
- C08K7/06—Elements
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L2201/00—Properties
- C08L2201/04—Antistatic
Landscapes
- Chemical & Material Sciences (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Compositions Of Macromolecular Compounds (AREA)
- Processes Of Treating Macromolecular Substances (AREA)
Abstract
The invention belongs to the technical field of high polymer materials, and discloses an anti-wear and anti-static polyether ether ketone based composite material, a preparation method and an application thereof, wherein the preparation method comprises the following steps: uniformly mixing self-lubricating polyether-ether-ketone and carbon fiber through mechanical grinding to obtain mixed powder; and then, placing the mixed powder under the vacuum condition with the pressure of 10-20 MPa for hot-pressing sintering treatment to obtain the anti-wear antistatic polyether ether ketone based composite material. The composite material has the characteristics of low friction coefficient, low wear rate, small friction static electricity and the like, and is simple in preparation process and good in controllability. The material is suitable for use at normal temperature and 60-260 ℃. Has important application prospect in the fields of aerospace and automobile manufacturing as a solid lubricating material.
Description
Technical Field
The invention relates to the technical field of high polymer materials, in particular to an anti-wear and anti-static polyether ether ketone based composite material and a preparation method and application thereof.
Background
The polyether-ether-ketone is a thermoplastic resin, has excellent heat resistance, friction resistance, corrosion resistance and good mechanical property as a special high polymer material, so that the polyether-ether-ketone becomes an attractive matrix material of a composite material and is widely applied to the industries of aerospace, medical appliances, automobiles and electronics.
In the prior art, different preparation methods are adopted for polyether ether ketone based composite materials, so that various properties of the materials are different, and the currently mature polymer composite material has good frictional wear performance under the conditions of room temperature, low speed and low load, but the frictional wear performance is rapidly reduced under the severe conditions of high temperature, high speed and heavy load, so that the application range of the material is limited.
Therefore, the invention provides an anti-wear antistatic polyether ether ketone based composite material and a preparation method and application thereof.
Disclosure of Invention
In order to solve the defects in the prior art, the invention provides an anti-wear and anti-static polyether ether ketone based composite material, and a preparation method and application thereof.
The invention relates to an anti-wear antistatic polyether ether ketone based composite material, a preparation method and application thereof, which are realized by the following technical scheme:
the first purpose of the invention is to provide a preparation method of an anti-wear and anti-static polyether ether ketone based composite material, which comprises the following steps:
the self-lubricating polyether-ether-ketone and the carbon fiber are uniformly mixed by mechanical grinding, and then the mixture is placed under the vacuum condition with the pressure of 10-20 MPa for hot-pressing sintering treatment, so that the wear-resistant antistatic polyether-ether-ketone based composite material is obtained.
Further, the hot-pressing sintering treatment comprises the following steps: firstly, the temperature is raised from room temperature to 300 ℃ at the heating rate of 50-60 ℃/min, then the temperature is raised from 300 ℃ to 350 ℃ at the heating rate of 8-10 ℃/min, and the temperature is kept for 5-15 min.
Further, the mass ratio of the self-lubricating polyetheretherketone to the carbon fiber is 4-19.
Further, the self-lubricating polyetheretherketone is PEEK 450G powder, and the particle size thereof is 12.5 μm.
Further, the density of the short carbon fiber is 1.8g/cm 3 The diameter of the cross section of the nano-composite material is 900 meshes, and the length-diameter ratio is 6-8.
Further, the density of the anti-wear antistatic polyether ether ketone based composite material is not more than 1.5g/cm 3 。
Furthermore, the mechanical grinding is dry ball milling, the ball-material ratio is 1-2, the rotating speed is 200-300 r/min, and the ball milling time is 4-8 h.
Furthermore, the grinding pot and the grinding ball of the ball mill are made of tungsten carbide hard alloy.
Further, the self-lubricating polyether-ether-ketone is dried before ball milling, the drying temperature of the drying is 90-110 ℃, and the drying time is 4-12 h.
Further, the vacuum degree of the vacuum condition is 10 -1 ~10 0 Pa。
The second purpose of the invention is to provide an antiwear and antistatic polyether ether ketone based composite material prepared by the preparation method.
The third purpose of the invention is to provide the application of the anti-wear antistatic polyether ether ketone based composite material prepared by the preparation method in anti-wear antistatic materials.
Compared with the prior art, the invention has the following beneficial effects:
according to the invention, the self-lubricating polyether-ether-ketone and the short carbon fibers are firstly dried to remove moisture in the material, so that the carbon fiber powder is better dispersed in the process of mixing with the polyether-ether-ketone matrix powder, and thus, the carbon fiber powder forms a communicated conductive network in the hot-pressing sintering process, and static electricity generated by friction is reduced. In addition, the temperature is increased to 300 ℃ in two stages for sintering in the sintering process, so that the mixed powder is fully heated in a short time to prepare for the reaction of the powder at a high temperature, and then the temperature is slowly increased to 350 ℃, so that the powder in the cavity of the graphite mold is uniformly heated while the instability of the heat preservation temperature caused by the excessively high temperature increase rate is prevented, and the solid material with high density is formed.
The material has low density and high hardness; the friction coefficient is low and stable, the wear rate is low, and the lubricating property is good; the friction static electricity is low, and the antistatic performance is good; the preparation process is simple and easy to operate, and the material performance can be regulated and controlled by adjusting the formula and the process.
Drawings
FIG. 1 is a room temperature friction curve of a polyether ether ketone based composite prepared according to comparative example 1 of the present invention at three temperatures;
FIG. 2 is a graph showing the wear rate at room temperature of polyether ether ketone based composites prepared according to comparative example 1 of the present invention at three temperatures;
FIG. 3 is a room temperature friction curve for a material of the present invention;
FIG. 4 is a graph of the room temperature wear rate of the material of the present invention; wherein the histogram is the materials of comparative example 1, example 2, example 3 and example 4 in order from left to right;
FIG. 5 is a tribostatic diagram of a material of the present invention; wherein the histogram is the materials of comparative example 1, example 2, example 3 and example 4 in order from left to right.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention.
Example 1
The embodiment provides an anti-wear antistatic polyether ether ketone-based composite material, which is prepared by the following steps:
weighing self-lubricating polyether-ether-ketone and short carbon fiber according to the mass ratio of 95.
Loading the obtained mixed powder into graphite mold, and placing under pressure of 15MPa and vacuum degree of less than 1 × 10 -1 And (3) carrying out hot-pressing sintering in a vacuum rapid hot-pressing sintering furnace of Pa, firstly heating from room temperature to 300 ℃ at the heating rate of 55 ℃/min, then heating from 300 ℃ to 350 ℃ at the heating rate of 9 ℃/min, and keeping the temperature for 10min to obtain the wear-resistant antistatic polyether ether ketone based composite material.
Example 2
The embodiment provides an anti-wear antistatic polyether ether ketone based composite material, and the anti-wear antistatic polyether ether ketone based composite material is prepared by the following steps:
weighing self-lubricating polyether ether ketone and short carbon fiber according to the mass ratio of 90.
The obtained mixed powder was charged into a graphite mold having the same dimensions as in example 1 under a pressure of 15MPa and a vacuum degree of less than 1X 10 -1 And (3) heating the mixture from room temperature to 300 ℃ at the heating rate of 55 ℃/min in a vacuum rapid hot-pressing sintering furnace of Pa, subsequently heating the mixture from 300 ℃ to 350 ℃ at the heating rate of 9 ℃/min, and preserving the heat for 10min to obtain the wear-resistant antistatic polyether ether ketone based composite material.
Example 3
The embodiment provides an anti-wear antistatic polyether ether ketone based composite material, and the anti-wear antistatic polyether ether ketone based composite material is prepared by the following steps:
weighing self-lubricating polyether-ether-ketone and short carbon fiber according to the mass ratio of 85 to 15, respectively, placing the self-lubricating polyether-ether-ketone and short carbon fiber in a high-energy ball mill, and mixing for 6 hours at the ball material ratio of 2.
The obtained mixed powder was charged into a graphite mold having the same dimensions as in example 1 under a pressure of 15MPa and a vacuum degree of less than 1X 10 -1 And (3) heating the mixture from room temperature to 300 ℃ at the heating rate of 55 ℃/min in a vacuum rapid hot-pressing sintering furnace of Pa, subsequently heating the mixture from 300 ℃ to 350 ℃ at the heating rate of 9 ℃/min, and preserving the heat for 10min to obtain the wear-resistant antistatic polyether ether ketone based composite material.
Example 4
The embodiment provides an anti-wear antistatic polyether ether ketone-based composite material, which is prepared by the following steps:
the self-lubricating polyether-ether-ketone and the short carbon fiber are respectively weighed according to the mass ratio of 80.
The obtained mixed powder was charged into a graphite mold having the same dimensions as in example 1 under a pressure of 15MPa and a vacuum degree of less than 1X 10 -1 And (3) heating the mixture from room temperature to 300 ℃ at the heating rate of 55 ℃/min in a vacuum rapid hot-pressing sintering furnace of Pa, subsequently heating the mixture from 300 ℃ to 350 ℃ at the heating rate of 9 ℃/min, and preserving the heat for 10min to obtain the wear-resistant antistatic polyether ether ketone based composite material.
Example 5
The embodiment provides an anti-wear antistatic polyether ether ketone based composite material, and the anti-wear antistatic polyether ether ketone based composite material is prepared by the following steps:
weighing self-lubricating polyether-ether-ketone and short carbon fiber according to the mass ratio of 95.
Loading the obtained mixed powder into graphite mold under pressure of 10MPa and vacuum degree of less than 1 × 10 -1 And (3) heating the mixture from room temperature to 300 ℃ at the heating rate of 50 ℃/min in a vacuum rapid hot-pressing sintering furnace of Pa, subsequently heating the mixture from 300 ℃ to 350 ℃ at the heating rate of 8 ℃/min, and preserving the heat for 30min to obtain the wear-resistant antistatic polyether ether ketone based composite material.
Example 6
The embodiment provides an anti-wear antistatic polyether ether ketone based composite material, and the anti-wear antistatic polyether ether ketone based composite material is prepared by the following steps:
weighing self-lubricating polyether-ether-ketone and short carbon fiber according to the mass ratio of 95.
Placing the obtained mixed powder into a graphite mold, and placing under a pressure of 15MPa and a vacuum degree of less than 1 × 10 0 And (2) heating the mixture from room temperature to 300 ℃ at the heating rate of 60 ℃/min in a vacuum rapid hot-pressing sintering furnace of Pa, subsequently heating the mixture from 300 ℃ to 350 ℃ at the heating rate of 10 ℃/min, and preserving the heat for 20min to obtain the wear-resistant antistatic polyether ether ketone based composite material.
Comparative example 1
The only difference from example 1 is:
the polyetheretherketone powder was directly put into a drying oven for 12 hours without adding short carbon fibers, completely dried, and then charged into a graphite mold having the same size as in example 1 to be subjected to a hot press sintering process. The other operations were the same as those in example 1.
Experimental part
In order to verify the properties of the abrasion resistant, antistatic polyether ether ketone based composites of the present invention, the following tests were conducted on the materials of examples 1-4 and comparative example 1.
Density and hardness of material
The density of the materials of the comparative example 1 and the example 1 is measured by adopting an Archimedes principle; the hardness of the materials of comparative example 1 and example 1 was measured using a digital shore durometer, and the results are shown in table 1.
TABLE 1 Density and Shore hardness of the materials
Test examples | Density (g/cm) | Shore Hardness (HD) |
Comparative example 1 | 1.3 | 85 |
Example 1 | 1.5 | 87 |
Coefficient of friction and wear rate of the material
The frictional wear performance of the invention is evaluated by a UMT-2 multifunctional frictional wear testing machine and a three-dimensional profile instrument.
The friction coefficient and the wear rate of the polyetheretherketone material of the comparative example 1 were tested at three molding temperatures (340 ℃, 345 ℃ and 350 ℃) according to the above test conditions to obtain a friction curve (as shown in fig. 1) and a wear rate curve (as shown in fig. 2) at the three molding temperatures, and the average friction coefficient and the wear rate of the material of the comparative example 1 at the three molding temperatures can be obtained according to fig. 1 and 2, and the results are shown in table 2.
It should be noted that the melting point of the polyetheretherketone material is 343 ℃, so the preparation temperature near three melting points is selected for the study. The temperature is too low, the material is not melted, which is equivalent to pressing and forming material powder, and the performance is poor; the material is completely melted when the temperature is too high, and the material completely flows out of the graphite grinding tool through the hot pressing process, so that the forming cannot be carried out.
TABLE 2 Friction coefficient and wear rate of the material of comparative example 1 and GCr15 steel ball matched pair
Temperature (. Degree.C.) | T1(340) | T2(345) | T3(350) |
Average coefficient of friction | 0.34 | 0.27 | 0.26 |
Wear and tearRate (10) -4 mm 3 /Nm) | 13.2 | 3.49 | 0.513 |
In order to verify the effect of different addition amounts of short carbon fibers on the performance of the materials, the friction coefficient and wear rate of the materials of examples 1-4 and comparative example 1 were tested by the present invention, a friction curve (shown in fig. 3) and a wear rate curve (shown in fig. 4) of the materials of examples 1-4 and comparative example 1 were obtained, respectively, and the average friction coefficient and wear rate of the materials of examples 1-4 and comparative example 1 were obtained according to fig. 3 and 4, and the results are shown in table 3.
TABLE 3 coefficient of friction and wear rate of the material of examples 1-4 and comparative example 1 in pairing with the GCr15 steel ball
Test examples | Comparative example 1 | Example 1 | Example 2 | Example 3 | Example 4 |
Average coefficient of friction | 0.272 | 0.255 | 0.256 | 0.250 | 0.247 |
Wear rate (10) -5 mm 3 /Nm) | 18.5 | 2.59 | 1.35 | 0.88 | 0.56 |
(III) antistatic Property test
Antistatic properties of the present invention the materials prepared in examples 1 to 4 and comparative example 1 were respectively subjected to tribostatic measurements using an FMX-003 tribostatic meter, and the test results are shown in fig. 5 and table 4.
Wherein, the testing conditions of the FMX-003 tribostatic electricity meter are as follows:
the dual ball is GCr15 steel ball, the load is 50N, the sliding linear velocity is 0.13m/s, the friction radius is 4mm, and the running time is 30min.
TABLE 4 tribostatic electricity of material of examples 1-4 and comparative example 1 in pairing with GCr15 steel balls
Test examples | Comparative example 1 | Example 1 | Example 2 | Example 3 | Example 4 |
Average friction static electricity (V) | 213.33 | 193.33 | 166.67 | 43.33 | 3.33 |
From the above tables 1 to 4, it can be seen that the hardness of the material prepared according to the present invention is improved and the thermal conductivity is increased by 1.5 times, compared to the comparative example. Because the hardness is improved, the surface of the material has a certain supporting function, so that the frictional wear performance of the material is improved; secondly, due to the fact that the heat conductivity coefficient is increased, the heat of the friction surface is reduced, and abrasion of materials due to friction heat is reduced. The invention selects the high-conductivity carbon fibers to disperse in the matrix material, not only plays a role in supporting and reinforcing, but also forms a communicated conductive network in the matrix material, thereby reducing friction static electricity.
It is to be understood that the above-described embodiments are only some of the embodiments of the present invention, and not all of the embodiments. 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.
Claims (7)
1. The preparation method of the anti-wear antistatic polyether ether ketone based composite material is characterized by comprising the following steps:
uniformly mixing self-lubricating polyether-ether-ketone and carbon fiber through mechanical grinding to obtain mixed powder; then placing the mixed powder under the vacuum condition with the pressure of 10-20 MPa for hot-pressing sintering treatment to obtain the wear-resistant antistatic polyether ether ketone based composite material;
the hot-pressing sintering treatment comprises the following steps: heating from room temperature to 300 ℃ at a heating rate of 50-60 ℃/min, then heating from 300 ℃ to 350 ℃ at a heating rate of 8-10 ℃/min, and preserving heat for 5-15min;
the mass ratio of the self-lubricating polyether-ether-ketone to the carbon fiber is 4 to 19;
the mechanical grinding is dry ball milling;
the self-lubricating polyether-ether-ketone is further dried before ball milling, wherein the drying temperature of the drying is 90-110 ℃, and the drying time is 4-12h.
2. The preparation method according to claim 1, wherein the self-lubricating polyetheretherketone is PEEK 450G powder and has a particle size of 12.5 μm;
the density of the carbon fiber is 1.8g/cm 3 The diameter of the cross section of the steel wire mesh is 900 meshes, and the length-diameter ratio is 6 to 8.
3. The process according to claim 1, wherein the antiwear, antistatic polyether ether ketone based composite has a density not exceeding 1.5g/cm 3 。
4. The preparation method of claim 1, wherein the dry ball milling has a ball-to-material ratio of 1-2, a rotation speed of 200-300 r/min and a ball milling time of 4-8 h.
5. The method of claim 1, wherein the vacuum condition has a vacuum degree of 10 -1 ~10 0 Pa。
6. An abrasion-resistant antistatic polyether ether ketone based composite material prepared by the preparation method of any one of claims 1 to 5.
7. Use of the abrasion resistant antistatic polyether ether ketone based composite material according to claim 6 in an abrasion resistant antistatic material.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
CN202111416945.8A CN113956609B (en) | 2021-11-25 | 2021-11-25 | Wear-resistant antistatic polyether ether ketone based composite material and preparation method and application thereof |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
CN202111416945.8A CN113956609B (en) | 2021-11-25 | 2021-11-25 | Wear-resistant antistatic polyether ether ketone based composite material and preparation method and application thereof |
Publications (2)
Publication Number | Publication Date |
---|---|
CN113956609A CN113956609A (en) | 2022-01-21 |
CN113956609B true CN113956609B (en) | 2023-03-24 |
Family
ID=79472246
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
CN202111416945.8A Active CN113956609B (en) | 2021-11-25 | 2021-11-25 | Wear-resistant antistatic polyether ether ketone based composite material and preparation method and application thereof |
Country Status (1)
Country | Link |
---|---|
CN (1) | CN113956609B (en) |
Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN109880288A (en) * | 2019-03-21 | 2019-06-14 | 中国科学院兰州化学物理研究所 | A kind of polyether ether ketone self-lubricating composite material and preparation method and application |
Family Cites Families (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN106147126A (en) * | 2015-04-16 | 2016-11-23 | 黑龙江鑫达企业集团有限公司 | A kind of preparation method of high-performance poly ether ether ketone/chopped carbon fiber composite |
CN105778407A (en) * | 2016-04-25 | 2016-07-20 | 苏州亚科塑胶有限公司 | Polyether-ether-ketone heat conduction composite material and preparation method thereof |
CN110819065A (en) * | 2019-11-08 | 2020-02-21 | 太原理工大学 | Conductive wear-resistant light polyether ether ketone based composite material and preparation method thereof |
AU2021105894A4 (en) * | 2021-08-19 | 2021-10-21 | Wuhan Research Institute Of Materials Protection | Antifriction and antiwear composite material for marine operation kinematic pair and preparation method thereof |
-
2021
- 2021-11-25 CN CN202111416945.8A patent/CN113956609B/en active Active
Patent Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN109880288A (en) * | 2019-03-21 | 2019-06-14 | 中国科学院兰州化学物理研究所 | A kind of polyether ether ketone self-lubricating composite material and preparation method and application |
Also Published As
Publication number | Publication date |
---|---|
CN113956609A (en) | 2022-01-21 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
CN108658613B (en) | Method for preparing automobile brake disc by short fiber die pressing | |
US3756982A (en) | Antifriction polymer materials and method of producing same | |
US4376710A (en) | High load carrying polyimide lubricative composites | |
CN111909477A (en) | High-performance carbon oxide fiber/graphite/polyimide modified polytetrafluoroethylene high-molecular composite material and preparation method thereof | |
CN113956609B (en) | Wear-resistant antistatic polyether ether ketone based composite material and preparation method and application thereof | |
CN104959608B (en) | A kind of nano silicon carbide granulate copper-base friction plate and preparation method thereof | |
CN106636725A (en) | Copper graphene-based electric contact material and preparation method thereof | |
CN108103348A (en) | A kind of copper-based wear-resistant material available for high-speed train braking | |
CN106939381A (en) | A kind of copper silver-based self-lubricating composite and preparation method thereof | |
CN115260676B (en) | Polytetrafluoroethylene-based composite material, preparation method thereof and application of polytetrafluoroethylene-based composite material as high-speed sealing material | |
CN109027006A (en) | A kind of composite sliding bearing and preparation method thereof | |
CN107177145A (en) | Filling-modified polytetrafluoroethylmaterial material and its application and preparation method | |
CN109354502B (en) | Self-lubricating silicon nitride-based composite material with high wear-resistant surface in high-temperature environment | |
CN111364256A (en) | Self-lubricating fabric composite material and preparation method thereof | |
CN109181208B (en) | Polyformaldehyde composite material and preparation method thereof | |
CN111961944B (en) | Wide-temperature-range self-lubricating VN-AgMoS2Composite material and preparation method thereof | |
CN109705503A (en) | A kind of fluorine-containing wear-resistant material and the preparation method and application thereof | |
CN111906301A (en) | Copper-based graphite self-lubricating gradient functional material and preparation method thereof | |
CN105803297A (en) | Boron carbide particle enhanced aluminum matrix composite and preparation method thereof | |
JP4209484B2 (en) | Sliding carbon material, sealing material using sliding carbon material, and manufacturing method of sliding carbon material | |
CN1114259A (en) | Creep-resistant composite material for valve base and producing process thereof | |
CN109337265A (en) | A kind of automobile shock absorber piston film and preparation method thereof | |
CN116218219B (en) | Wear-resistant self-lubricating composite material based on naphthyridine biphenyl polyarylether resin and preparation method thereof | |
CN107353638A (en) | A kind of resin-matrix friction material for being granulated zirconium oxide filling and preparation method thereof | |
CN103628058B (en) | A kind of preparation method of high-wearing feature metal-based self-lubricating PTFE coating |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
PB01 | Publication | ||
PB01 | Publication | ||
SE01 | Entry into force of request for substantive examination | ||
SE01 | Entry into force of request for substantive examination | ||
GR01 | Patent grant | ||
GR01 | Patent grant |