CN110016229B - Low-oil-outlet-rate microporous core valve material and preparation method thereof - Google Patents

Low-oil-outlet-rate microporous core valve material and preparation method thereof Download PDF

Info

Publication number
CN110016229B
CN110016229B CN201810019389.2A CN201810019389A CN110016229B CN 110016229 B CN110016229 B CN 110016229B CN 201810019389 A CN201810019389 A CN 201810019389A CN 110016229 B CN110016229 B CN 110016229B
Authority
CN
China
Prior art keywords
core valve
valve material
molding
type polyimide
anhydride type
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
Application number
CN201810019389.2A
Other languages
Chinese (zh)
Other versions
CN110016229A (en
Inventor
孙小波
楚婷婷
王枫
李媛媛
宁仲
张亭亭
李江斌
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Luoyang Bearing Research Institute Co Ltd
Original Assignee
Luoyang Bearing Research Institute Co Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Luoyang Bearing Research Institute Co Ltd filed Critical Luoyang Bearing Research Institute Co Ltd
Priority to CN201810019389.2A priority Critical patent/CN110016229B/en
Publication of CN110016229A publication Critical patent/CN110016229A/en
Application granted granted Critical
Publication of CN110016229B publication Critical patent/CN110016229B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L79/00—Compositions of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing nitrogen with or without oxygen or carbon only, not provided for in groups C08L61/00 - C08L77/00
    • C08L79/04—Polycondensates having nitrogen-containing heterocyclic rings in the main chain; Polyhydrazides; Polyamide acids or similar polyimide precursors
    • C08L79/08—Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L2205/00—Polymer mixtures characterised by other features
    • C08L2205/02—Polymer mixtures characterised by other features containing two or more polymers of the same C08L -group
    • C08L2205/025—Polymer mixtures characterised by other features containing two or more polymers of the same C08L -group containing two or more polymers of the same hierarchy C08L, and differing only in parameters such as density, comonomer content, molecular weight, structure
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L2205/00—Polymer mixtures characterised by other features
    • C08L2205/03—Polymer mixtures characterised by other features containing three or more polymers in a blend

Landscapes

  • Chemical & Material Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Organic Chemistry (AREA)
  • Casting Or Compression Moulding Of Plastics Or The Like (AREA)

Abstract

The invention relates to a microporous core valve material with low oil outlet rate and a preparation method thereof. The core valve material is prepared from the following raw materials in percentage by weight: 40-60% of diether anhydride type polyimide, 20-50% of anhydride type polyimide and 10-20% of polytetrafluoroethylene. The low-oil-out-rate microporous core valve material provided by the invention is prepared from the bis-ether-anhydride type polyimide, the homoanhydride type polyimide and the polytetrafluoroethylene according to a certain proportion, and has the advantages of high tensile strength, high hardness and good processability on the basis of meeting the requirements of low porosity and low permeability of the core valve material. The raw materials are selected reasonably and cooperatively, the pore structure of the core valve material is stable and easy to control, and the batch stability of the core valve material production is improved.

Description

Low-oil-outlet-rate microporous core valve material and preparation method thereof
Technical Field
The invention belongs to the technical field of bearing materials, and particularly relates to a low-oil-outlet-rate microporous core valve material and a preparation method thereof.
Background
Along with the continuous extension of bearing assembly life-span, the lubricated oil mass that porous holder contains can not satisfy the demand, has designed the oil feed cavity that has stored quantitative lubricating oil in subassembly internal design, and lubricating oil in the oil feed cavity is carried to the bearing position that needs lubrication through crossing oily passageway. Generally, the oil passage is a circular hole, the core valve material is arranged in the oil passage and matched with the oil passage, and the core valve material has a cylindrical structure. The core valve material requires extremely low oil outlet rate, and also has small pore diameter, low porosity, low permeability and good processability, and the manufacturing difficulty is extremely high.
The traditional core valve material mostly adopts a porous cloth-sandwiched bakelite material, but the material is easy to break when processing threads of the core valve material, and the rejection rate is too high; in addition, the oil supply rate of the porous cloth-sandwiched bakelite material is mainly related to the number, continuity and orientation of cotton threads in the cross section, and the cotton fibers are easy to be soaked by phenolic resin to cause the functional loss of capillary action, so that the stability of the material is poor.
Disclosure of Invention
The invention aims to provide a microporous core valve material with a low oil outlet rate, so that the problems of poor processability and stability of the existing core valve material are solved.
The second purpose of the invention is to provide a preparation method of the microporous core valve material with low oil outlet rate.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows:
a low oil-out rate microporous core valve material is prepared from the following raw materials in percentage by weight: 40-60% of diether anhydride type polyimide, 20-50% of anhydride type polyimide and 10-20% of polytetrafluoroethylene.
The low-oil-out-rate microporous core valve material provided by the invention is prepared from the bis-ether-anhydride type polyimide and the pyromellitic-anhydride type polyimide polytetrafluoroethylene according to a certain proportion, and has the advantages of high tensile strength, high hardness and good processability on the basis of meeting the requirements of low porosity and low permeability of the core valve material. The raw materials are selected reasonably and cooperatively, the pore structure of the core valve material is stable and easy to control, and the batch stability of the core valve material production is improved.
The diether anhydride type polyimide and the homoanhydride type polyimide are conventional varieties of polyimide and can be obtained through conventional channels sold in the market. The density of the bisether anhydride type polyimide molding powder (resin powder) is 1.35 to 1.40g/cm3The glass transition temperature is 325-335 ℃. The density of the homoanhydride type polyimide molding powder (resin powder) is 1.33 to 1.36g/cm3The glass transition temperature is 385-395 ℃. The mesh number of the diether anhydride type polyimide molding powder and the homogeneous anhydride type polyimide molding powder is not less than 400 meshes. The density of the polytetrafluoroethylene molding powder (resin powder) is 2.15-2.20g/cm3The melting point was 327 ℃. The mesh number of the polytetrafluoroethylene molding powder is not less than 100 mesh.
Preferably, the low oil-out rate microporous core valve material is prepared from the following raw materials in percentage by weight: 40% of diether anhydride type polyimide, 45% of anhydride type polyimide and 15% of polytetrafluoroethylene. The microporous core valve material prepared by the proportion has the best comprehensive properties such as permeability, processability, tensile strength and the like.
The preparation method of the low-oil-yielding-rate microporous core valve material adopts the technical scheme that:
a preparation method of a microporous core valve material with low oil outlet rate comprises the following steps:
1) uniformly mixing the diether anhydride type polyimide molding powder, the anhydride type polyimide molding powder and the polytetrafluoroethylene molding powder to obtain a molding material;
2) and (3) putting the molding material into a molding die, pressing the molding material to the designed volume position of the core valve material, and carrying out heat preservation and pressure maintaining molding at 360-400 ℃ to obtain the composite material.
In the step 1), the mesh number of the diether anhydride type polyimide molding powder and the anhydride type polyimide molding powder is not less than 400 meshes, and the mesh number of the polytetrafluoroethylene molding powder is not less than 100 meshes.
In the step 2), the feeding amount of the molding material is calculated according to the designed porosity and the designed volume of the core valve material. Preferably, the forming die comprises a die body and a limiting sleeve, the die body is arranged inside and outside the die body, the die body comprises an outer sleeve, a base and a punch, the base and the punch are matched with the outer sleeve during forming, the outer sleeve, the base and the punch enclose a die cavity for forming the core valve material, and the upper end of the limiting sleeve is provided with a limiting surface in stop fit with a pressure head of a press during pressing. The core valve material has small volume, and the conventional forming die has the phenomena of uneven pressing force and inconvenient operation, so that the limiting and hot-press forming of the core valve material by adopting the pressing die has the advantages of simple structure, good reusability of the die and uniform pressing.
In the step 2), the pressing speed is 3-10 mm/min. The pressure for the heat preservation and pressure maintaining molding is 1200-1500kg/cm2. The time for heating to 360-400 ℃ is 60-90 min. The heat preservation time at 360-400 ℃ is 30-60 min. The limiting-hot press molding is carried out under the molding parameters, so that the pressing process can be uniformly and stably carried out, the pore structure of the core valve material is favorably optimized, and the core valve material is further optimizedOil supply and oil discharge performance of the material.
The low oil-out rate microporous core valve material has the characteristics of small pore diameter, low porosity, higher tensile strength, high hardness and low permeability, and can be used as a core valve material and a bearing retainer material, so that the oil supply and lubrication performance of a bearing assembly is further optimized on the premise of meeting the requirement of easy processing performance of the material.
Drawings
Fig. 1 is a schematic structural view of a molding die used in the present invention.
Detailed Description
The following examples are provided to further illustrate the practice of the invention. In the following examples, the type of the bisether anhydride type polyimide molding powder was HI-P-100, and the density was 1.38g/cm3The glass transition temperature is 330 ℃, and the glass transition temperature is purchased from Kawasaki polyimide materials Co., Ltd; the type of the pyromellitic anhydride type polyimide molding powder is P84NT2, and the density is 1.36g/cm3The glass transition temperature is 393 ℃, and the glass transition temperature is purchased from winning creation company; the polytetrafluoroethylene molding powder was M-18F, and had a density of 2.18g/cm3Melting point 327 ℃ from Dajin.
Example 1
The low oil-out rate microporous core valve material of the embodiment is prepared from the following raw materials in percentage by weight: 40% of bis ether anhydride type polyimide molding powder, 45% of anhydride type polyimide molding powder and 15% of polytetrafluoroethylene molding powder.
The preparation method of the low oil-out rate microporous core valve material of the embodiment comprises the following steps:
1) respectively placing the diether anhydride type polyimide molding powder, the homoanhydride type polyimide molding powder and the polytetrafluoroethylene molding powder in a drying box for drying treatment, wherein the thickness of the raw material powder is not more than 30mm, the drying temperatures of the three raw materials are respectively 150 ℃, 240 ℃ and 100 ℃, drying for 2h, taking out and cooling to room temperature, sieving the diether anhydride type polyimide molding powder and the homoanhydride type polyimide molding powder through a 400-mesh sieve, sieving the polytetrafluoroethylene molding powder through a 100-mesh sieve, and independently sealing and storing in a drying cabinet for later use.
2) Taking raw materials according to the proportion, putting the raw materials into a high-speed mixer, stirring for 3 times, wherein the rotating speed of each stirring is 1440r/min, the stirring time is 2 hours, observing the color difference of the mixed materials by using a forty-fold microscope, obtaining qualified molding materials when no obvious color difference exists, and sealing and storing for later use.
The double-ether anhydride type polyimide molding powder is gray brown, the anhydride type polyimide molding powder is light yellow, the polytetrafluoroethylene molding powder is white, the materials after being uniformly mixed are light yellow, and whether the mixed materials are light yellow with uniform color difference or not can be conveniently observed through a forty-fold microscope.
3) And (2) putting the qualified molding material obtained in the step 2) into a molding die, wherein the structural schematic diagram of the molding die is shown in fig. 1 and comprises a die body 1 and a limiting sleeve 2 which are arranged inside and outside, the die body 1 comprises an outer sleeve 10, a base 11 and a punch 12 which are matched with the outer sleeve 10 during molding, the base 11 is positioned at the lower end inside the outer sleeve, the peripheral surface of the base 11 is in sliding fit with the inner wall surface of the outer sleeve 10, the punch 12 is positioned at the upper end of the outer sleeve, the peripheral surface of the punch 12 is in sliding fit with the inner wall surface of the outer sleeve 10, and the inner wall surface of the outer sleeve, the lower surface of the punch and the upper surface of. The height of the limiting sleeve 2 is larger than that of the outer sleeve 10, the inner diameter of the limiting sleeve 2 is larger than that of the outer sleeve 10, a transverse interval is formed between the inner side wall of the limiting sleeve 2 and the outer side wall of the sleeve 10, and a limiting surface 14 matched with a pressure head of a press in a blocking mode during pressing is formed on the upper end face of the limiting sleeve.
The diameter D of the core valve material is set to be 3.0mm, the height H is 12.0mm, the porosity is 7%, the diameter D 'of the set volume of the core valve material can be set to be D +3mm is 6mm, the height H' H +4mm is 16mm, the density of the core valve material under the porosity is calculated according to the theoretical density of the qualified molding material, and the feeding amount of the qualified molding material is calculated by combining the set volume of the core valve material, specifically: the theoretical density of the synthesized molding material is rho 1.45g/cm3The density of the core valve material is rho' 1.38g/cm3×(1-7％)＝1.35g/cm3The material feeding amount is m ═ pi (D'/2)2Xh '× ρ' is 0.63 g. Height of the limiting sleeve is recorded as hLimiting positionThe height of the base is recorded as hBase seatThe height of the punch is recorded as hPunch headHeight of the core valve material is denoted as hCore valve materialControl hLimiting position＝hBase seat+hPunch head+hCore valve materialWhen the pressure head of the press presses the limiting surface of the limiting sleeve, the set volume position of the core valve material is reached.
Placing the forming die into a programmable hot press, controlling the speed of pressing to a set volume position (namely the upper end surface of a limiting sleeve) of the core valve material to be 5mm/min, and controlling the pressing pressure to be 1200kg/cm2And starting a heating program under the pressure to enable the temperature to reach 360 ℃ after 60min, keeping the pressure and preserving the heat for 50min, ending the program, and demolding when the temperature of a forming mold is lower than 220 ℃ to obtain the low-oil-yielding-rate microporous core valve material.
Example 2
The low oil-out rate microporous core valve material of the embodiment has the same specification as the embodiment 1, and is prepared from the following raw materials in percentage by weight: 40% of bis ether anhydride type polyimide molding powder, 40% of anhydride type polyimide molding powder and 20% of polytetrafluoroethylene molding powder.
The preparation method of the low oil-out rate microporous core valve material of the embodiment can refer to the preparation steps of the embodiment 1, and the difference is only in the step 3).
The diameter D of the core valve material is set to be 3.0mm, the height H is 12.0mm, the porosity is 6%, the diameter D 'of the set volume of the core valve material can be set to be D +3mm is 6mm, the height H' H +4mm is 16mm, the density of the core valve material under the porosity is calculated according to the theoretical density of the qualified molding material, and the feeding amount of the qualified molding material is calculated by combining the set volume of the core valve material, specifically: the theoretical density of the synthesized molding material is rho 1.48g/cm3The density of the core valve material is rho' 1.38g/cm3×(1-6％)＝1.30g/cm3The material feeding amount is m ═ pi (D'/2)2Xh '× ρ' is 0.65 g. Height of the limiting sleeve is recorded as hLimiting positionThe height of the base is recorded as hBase seatThe height of the punch is recorded as hPunch headHeight of the core valve material is denoted as hCore valve materialControl hLimiting position＝hBase seat+hPunch head+hCore valve materialWhen the pressure head of the press presses the limiting surface of the limiting sleeve, the set volume position of the core valve material is reached.
Placing the forming die into a programmable hot press, controlling the speed of pressing to a set volume position (namely the upper end surface of a limiting sleeve) of the core valve material to be 3mm/min, and controlling the pressing pressure to be 1200kg/cm2And starting a heating program under the pressure to enable the temperature to reach 380 ℃ after 60min, keeping the pressure and preserving the heat for 60min, ending the program, and demolding when the temperature of a forming mold is lower than 220 ℃ to obtain the low-oil-yielding-rate microporous core valve material.
Example 3
The low oil-out rate microporous core valve material of the embodiment has the same specification as the embodiment 1, and is prepared from the following raw materials in percentage by weight: 45% of bis ether anhydride type polyimide molding powder, 50% of homogeneous anhydride type polyimide molding powder and 5% of polytetrafluoroethylene molding powder.
The preparation method of the low oil-out rate microporous core valve material of the embodiment can refer to the preparation steps of the embodiment 1, and the difference is only in the step 3).
The diameter D of the core valve material is set to be 3.0mm, the height H is 12.0mm, the porosity is 9%, the diameter D 'of the set volume of the core valve material can be set to be D +3mm to be 6mm, the height H' H +4mm to be 16mm, the density of the core valve material under the porosity is calculated according to the theoretical density of the qualified molding material, and the feeding amount of the qualified molding material is calculated by combining the set volume of the core valve material, specifically: the theoretical density of the synthesized molding material is rho 1.40g/cm3The density of the core valve material is rho' 1.40g/cm3×(1-9％)＝1.27g/cm3The material feeding amount is m ═ pi (D'/2)2Xh '× ρ' is 0.60 g. Height of the limiting sleeve is recorded as hLimiting positionThe height of the base is recorded as hBase seatThe height of the punch is recorded as hPunch headHeight of the core valve material is denoted as hCore valve materialControl hLimiting position＝hBase seat+hPunch head+hCore valve materialWhen the pressure head of the press presses the limiting surface of the limiting sleeve, the set volume position of the core valve material is reached.
The molding die is placed into a programmable hot press,the speed of pressing to the set volume position of the core valve material (namely the upper end surface of the limiting sleeve) is controlled to be 7mm/min, and the pressing pressure reaches 1200kg/cm2And starting a heating program under the pressure to enable the temperature to reach 370 ℃ after 60min, keeping the pressure and preserving the heat for 50min, ending the program, and demolding when the temperature of a forming mold is lower than 220 ℃ to obtain the low-oil-yielding-rate microporous core valve material.
Test examples
The test example tests various performance indexes of the low oil-out rate microporous core valve material of each example, and the specific test results are shown in table 1.
TABLE 1 Performance index of Low oil Rate microporous core valve materials of the examples
Figure BDA0001543062300000051
Figure BDA0001543062300000061
As can be seen from the test results in Table 1, the low oil-out rate microporous core valve materials of examples 1-3 all have the characteristics of small pore size, low porosity, high tensile strength, high hardness, low permeability, good processability, and an oil-out rate of not more than 0.30 mg/day, and satisfy the oil-out rate requirements of the core valve materials for bearing assemblies of users.

Claims (5)

1. The preparation method of the microporous core valve material with the low oil outlet rate is characterized in that the microporous core valve material is prepared from the following raw materials in percentage by weight: 40-60% of diether anhydride type polyimide, 20-50% of anhydride type polyimide and 10-20% of polytetrafluoroethylene; the preparation method of the microporous core valve material comprises the following steps:
1) uniformly mixing the diether anhydride type polyimide molding powder, the anhydride type polyimide molding powder and the polytetrafluoroethylene molding powder to obtain a molding material;
the mesh number of the diether anhydride type polyimide molding powder and the homogeneous anhydride type polyimide molding powder is not less than 400 meshes, and the mesh number of the polytetrafluoroethylene molding powder is not less than 100 meshes;
2) putting the molding material into a molding die, pressing the molding material to the designed volume position of the core valve material, and carrying out heat preservation and pressure maintaining molding at 360-400 ℃ to obtain the material;
the forming die comprises a die body and a limiting sleeve, wherein the die body and the limiting sleeve are arranged inside and outside the die body, the die body comprises an outer sleeve, a base and a punch, the base and the punch are matched with the outer sleeve during forming, the outer sleeve, the base and the punch enclose a die cavity for forming a core valve material, and the upper end of the limiting sleeve is provided with a limiting surface in stop fit with a pressure head of a press during pressing.
2. The method for preparing a low oil-out rate microporous core valve material according to claim 1, wherein in the step 2), the pressing speed is 3 to 10 mm/min.
3. The method for preparing the microporous core valve material with low oil outlet rate of claim 1, wherein in the step 2), the pressure for the heat-preservation pressure-maintaining molding is 1200-1500kg/cm2。
4. The method for preparing a microporous valve core material with a low oil extraction rate as claimed in claim 1, wherein the time for raising the temperature to 360-400 ℃ is 60-90 min.
5. The method for preparing a microporous valve core material with low oil extraction rate as claimed in claim 1, wherein the time for the heat preservation at 360-400 ℃ is 30-60 min.
CN201810019389.2A 2018-01-09 2018-01-09 Low-oil-outlet-rate microporous core valve material and preparation method thereof Active CN110016229B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN201810019389.2A CN110016229B (en) 2018-01-09 2018-01-09 Low-oil-outlet-rate microporous core valve material and preparation method thereof

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN201810019389.2A CN110016229B (en) 2018-01-09 2018-01-09 Low-oil-outlet-rate microporous core valve material and preparation method thereof

Publications (2)

Publication Number Publication Date
CN110016229A CN110016229A (en) 2019-07-16
CN110016229B true CN110016229B (en) 2021-06-01

Family

ID=67187716

Family Applications (1)

Application Number Title Priority Date Filing Date
CN201810019389.2A Active CN110016229B (en) 2018-01-09 2018-01-09 Low-oil-outlet-rate microporous core valve material and preparation method thereof

Country Status (1)

Country Link
CN (1) CN110016229B (en)

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP5012819B2 (en) * 2009-01-14 2012-08-29 Ｄｉｃ株式会社 Polyimide resin composition
CN103160124A (en) * 2013-02-26 2013-06-19 洛阳轴研科技股份有限公司 Method for producing holder blank with ether anhydride type polyimide molding powder composite material
CN103756313A (en) * 2013-12-13 2014-04-30 洛阳轴研科技股份有限公司 Method used for increasing hear resistance of ketone-anhydride type polyimide retainer tube blank
CN105295047A (en) * 2015-11-30 2016-02-03 苏州太湖电工新材料股份有限公司 Polyimide polymer preparation method

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP5012819B2 (en) * 2009-01-14 2012-08-29 Ｄｉｃ株式会社 Polyimide resin composition
CN103160124A (en) * 2013-02-26 2013-06-19 洛阳轴研科技股份有限公司 Method for producing holder blank with ether anhydride type polyimide molding powder composite material
CN103756313A (en) * 2013-12-13 2014-04-30 洛阳轴研科技股份有限公司 Method used for increasing hear resistance of ketone-anhydride type polyimide retainer tube blank
CN105295047A (en) * 2015-11-30 2016-02-03 苏州太湖电工新材料股份有限公司 Polyimide polymer preparation method

Also Published As

Publication number Publication date
CN110016229A (en) 2019-07-16

Similar Documents

Publication Publication Date Title
CN109721344B (en) Porous ceramic material, porous ceramic and preparation method thereof
CN110303153B (en) Method for processing capillary core and method for assembling capillary core and tube shell
CN101425352B (en) Technical process for enhancing stability of NTC heat variable resistor
CN102992766A (en) Production process for high-density isotropic isostatic-pressed round graphite hollow-core blank
CN113603503B (en) Microporous ceramic atomizing core and preparation method thereof
US9196947B2 (en) Method for manufacturing resonant tube, resonant tube and cavity filter
CN110016229B (en) Low-oil-outlet-rate microporous core valve material and preparation method thereof
CN111763429A (en) Porous polyimide composite material for bearing retainer, preparation method of porous polyimide composite material and bearing retainer
CN107321983A (en) A kind of method for adjusting powder metallurgy copper base friction material porosity and pore structure
CA2531435A1 (en) Method of flow forming a metal part
CN113511910A (en) Preparation method of porous ceramic heating element and porous ceramic heating element
CN110028788B (en) Polyimide composite material, porous polyimide retainer, preparation method of porous polyimide retainer and bearing
CN110181059A (en) A kind of method of co-injection near-net-shape ultra-fine cemented carbide cutter green body
CN109808114B (en) Preparation method of bearing retainer material and preparation method of bearing retainer
CN105057668A (en) Sintering method of stainless steel fibre felt
CN112089104A (en) Manufacturing process of atomizing core and electronic atomizer
CN113735555A (en) Porous body, preparation method thereof and electronic cigarette using porous body
CN104708884A (en) Multilayer microporous fiber filter plate production process
CN104496498B (en) A kind of preparation method of bottom casting train wheel graphite jig
CN105837240A (en) Method for preparing carbon-carbon composite material for pantograph
CN210581002U (en) Atomizing core structure and electronic atomizer
US9976486B2 (en) Flow devices and methods of making the same
CN113290759A (en) Forming method of small-size polyimide self-lubricating composite retainer material
CN103992133A (en) Self-lubrication porous ceramic-based composite material and preparation method thereof
CN109774181B (en) Forming method of bar for manufacturing miniature bearing retainer

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