U.S. patent application number 17/134371 was filed with the patent office on 2022-04-21 for method for preparing matrix protective coating.
The applicant listed for this patent is NO. 59 INSTITUTE OF CHINA ORDNANCE INDUSTRY, UNIVERSITY OF SCIENCE AND TECHNOLOGY LIAONING. Invention is credited to Xu GAO, Feng GUO, Suying HU, Bo HUANG, Haiqing NING, Leifang SHEN, Hong SU, Xiaohui WANG, Di WU, Hulin WU, Shuai WU, Lin XIANG, Yunliang XIANG, Hao XIE, Zhiwen XIE, Huan XIONG.
Application Number | 20220119932 17/134371 |
Document ID | / |
Family ID | 1000005495566 |
Filed Date | 2022-04-21 |
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United States Patent
Application |
20220119932 |
Kind Code |
A1 |
WU; Hulin ; et al. |
April 21, 2022 |
METHOD FOR PREPARING MATRIX PROTECTIVE COATING
Abstract
Disclosed a method for preparing a matrix protective coating,
including a preprocessing step and a like transfer membrane coating
preparation step. The like transfer membrane coating preparation
step includes the following steps: mixing, drying and cooling YSZ
powder and polytetrafluoroethylene powder to obtain a mixture, and
then spraying the mixture onto the surface of a preprocessed matrix
by an atmospheric plasma spraying method, wherein spraying
parameters are set as follows: a moving speed of a spray gun is
440-460 mm/s; the current is 550-600 A, the voltage is 40-50 V, and
the power is 24.8-30 kW; the compressed air is 0.6-0.7 MPa; the
powder feeding carrier gas Ar is 3-6 L/min; a powder feeding rate
is 25-28 g/min; and a spraying distance is 108-112 mm. The wear
resistance of the coating of the present invention is significantly
improved; the corrosion resistance is excellent; and the
superhydrophobic property is excellent.
Inventors: |
WU; Hulin; (Chongqing,
CN) ; XIE; Zhiwen; (Anshan, CN) ; XIANG;
Lin; (Chongqing, CN) ; GAO; Xu; (Anshan,
CN) ; GUO; Feng; (Anshan, CN) ; NING;
Haiqing; (Chongqing, CN) ; XIONG; Huan;
(Anshan, CN) ; HU; Suying; (Anshan, CN) ;
WU; Shuai; (Chongqing, CN) ; XIE; Hao;
(Anshan, CN) ; SU; Hong; (Chongqing, CN) ;
WANG; Xiaohui; (Chongqing, CN) ; HUANG; Bo;
(Chongqing, CN) ; WU; Di; (Anshan, CN) ;
XIANG; Yunliang; (Chongqing, CN) ; SHEN; Leifang;
(Chongqing, CN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
NO. 59 INSTITUTE OF CHINA ORDNANCE INDUSTRY
UNIVERSITY OF SCIENCE AND TECHNOLOGY LIAONING |
Chongqing
Anshan |
|
CN
CN |
|
|
Family ID: |
1000005495566 |
Appl. No.: |
17/134371 |
Filed: |
December 26, 2020 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C23C 4/02 20130101; C23C
4/134 20160101; C23C 4/11 20160101 |
International
Class: |
C23C 4/134 20060101
C23C004/134; C23C 4/11 20060101 C23C004/11; C23C 4/02 20060101
C23C004/02 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 20, 2020 |
CN |
202011121503.6 |
Claims
1. A method for preparing a matrix protective coating, comprising a
preprocessing step and a like transfer membrane coating preparation
step, wherein the like transfer membrane coating preparation step
comprises the following steps: mixing, drying and cooling yttria
stabilized zirconia (YSZ) powder and polytetrafluoroethylene powder
to obtain a mixture, and then spraying the mixture onto a surface
of a preprocessed matrix by an atmospheric plasma spraying method;
during spraying, direct current (DC) arc is generated between a
cathode and an anode, which heats and ionizes an working gas into a
plasma and ejects the plasma from a nozzle to form a plasma flame;
the plasma flame includes an inner flame and an outer flame; a
high-temperature zone having a temperature far higher than a
vaporization temperature of the polytetrafluoroethylene powder is
formed in the inner flame and a low-temperature zone having a
temperature lower than the high-temperature zone is formed in the
outer flame; the mixture is fed by the outer flame; the
polytetrafluoroethylene powder is completely melt and the YSZ
powder is partially melt molten polytetrafluoroethylene powder and
molten YSZ powder are sprayed onto the matrix to form a deposited
coating; a surface of the deposited coating is impacted by a
non-molten YSZ powder; the non-molten YSZ forms a continuous
skeleton structure to fix the molten polytetrafluoroethylene
powder; wherein spraying parameters of the atmospheric plasma
spraying are set as follows: a moving speed of a spray gun is
440-460 mm/s; a current is 550-600 A, a voltage is 40-50 V, and a
power is 24.8-30 kW; a intensity of pressure of a compressed air is
0.6-0.7 MPa; the compressed air is used to carry and propel the
mixture; powder feeding carrier gas Ar is 3-6 L/min; a powder
feeding rate is 25-28 g/min; and a spraying distance is 108-112
mm.
2. The method for preparing the matrix protective coating according
to claim 1, wherein the preprocessing step comprises a sand
blasting step.
3. The method for preparing the matrix protective coating according
to claim 2, wherein sand blasting parameters are set as follows:
0.3-0.4 MPa air is taken as power; a spraying distance is 100-130
mm; an injection angle is 70.degree.-90.degree.; the injection
angle is an angle between the surface of the preprocessed matrix
and a blasting stream; and 60-150-mesh white fused alumina abrasive
is injected to the surface of the matrix.
4. The method for preparing the matrix protective coating according
to claim 1, wherein a mixing ratio of YSZ powder to
polytetrafluoroethylene powder is (92%-93%): (7%-8%), by mass
percent.
5. The method for preparing the matrix protective coating according
to claim 1, wherein drying refers to drying for 3 hat 50-90.degree.
C.
6. The method for preparing the matrix protective coating according
to claim 1, wherein a thickness of a like transfer membrane coating
is 20 .mu.m-40 .mu.m.
7. The method for preparing the matrix protective coating according
to claim 1, wherein the matrix is metal or ceramic material.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of priority from Chinese
Patent Application No. 202011121503.6, filed on Oct. 20, 2020. The
content of the aforementioned application, including any
intervening amendments thereto, is incorporated herein by reference
in its entirety.
TECHNICAL FIELD
[0002] The present invention belongs to the technical field of
surface protection, and particularly relates to a method for
preparing a matrix protective coating.
BACKGROUND OF THE PRESENT INVENTION
[0003] Organic polymers generally have low friction coefficient,
but poor wear resistance and high wear rate, and are easy to fall
off.
[0004] Researches show that surface protection is an effective way
to improve the surface wear resistance of an organic polymer
matrix. A patent document with a publication No. CN111701825A
prepares cylindrical porous yttria (Y.sub.2O.sub.3) stabilized
zirconia (YSZ) as a skeleton of a ceramic material by using
suspension plasma spraying (SPS); the skeleton is filled with
polyacrylonitrile (PAN)-modified PTFE self-lubricating polymer; and
then a PAN-PTFE modified coating material is smeared on a YSZ
coating, followed by vacuumizing under negative pressure and
curing. The principle is as follows: YSZ suspension is directly
subjected to plasma spraying as a spraying raw material to prepare
the YSZ coating, so that the problem that nano powder is easy to
grow up under a high temperature condition is solved; moreover,
precursor micelles pass through plasma flame flow at high speed,
the flying time is extremely short (less than 10.sup.-3 seconds),
and nucleation nano crystals collide with the matrix before growing
up and are deposited as the nano coating; secondly,
polyacrylonitrile (PAN) can increase cohesion between a transfer
membrane and a grinding surface, so that the transfer membrane can
adhere completely and firmly to the grinding surface and is not
easy to fall off, thereby reducing a cycling process from formation
of the transfer membrane to falling of the transfer membrane to
re-formation of the transfer membrane, and reducing abrasion loss;
and furthermore, under the negative pressure, the PAN-PTFE modified
coating material can be fully penetrated into the YSZ coating with
conical cylindrical pores, thereby reducing the porosity of the YSZ
coating, improving the compactness, reducing the friction
coefficient and wear rate and improving the wear resistance. The
coating prepared by the method has low friction coefficient and
wear rate, can more efficiently play the corrosion resistance and
hydrophobic property of a polytetrafluoroethylene material, and
solves the problems of large abrasion loss and poor wear
resistance. The wear rate is
80.times.10.sup.-6mm.sup.3N.sup.-1m.sup.-1, and the friction
coefficient is 0.42. However, the coating prepared by the method
cannot meet application needs.
SUMMARY OF THE PRESENT INVENTION
[0005] In view of this, a purpose of the present invention is to
provide a method for preparing a matrix protective coating.
[0006] In order to realize the above purpose, the present invention
adopts the following technical solution:
[0007] The method for preparing the matrix protective coating
includes a preprocessing step and a like transfer membrane coating
preparation step. The like transfer membrane coating preparation
step includes the following steps:
[0008] mixing, drying and cooling YSZ powder and
polytetrafluoroethylene powder to obtain a mixture, and then
spraying the mixture onto the surface of a preprocessed matrix by
an atmospheric plasma spraying method, wherein spraying parameters
are set as follows: a moving speed of a spray gun is 440-460 mm/s;
the current is 550-600 A, the voltage is 40-50 V, and the power is
24.8-30 kW; compressed air is 0.6-0.7 MPa; powder feeding carrier
gas Ar is 3-6 L/min; a powder feeding rate is 25-28 g/min; and a
spraying distance is 108-112 mm.
[0009] Further, the preprocessing step includes a sand blasting
step. Further, sand blasting parameters are set as follows: 0.3-0.4
MPa air is taken as power; a spraying distance is 100-130 mm; an
injection angle is 70.degree. -90.degree.; and multi-angular
60-150-mesh white fused alumina abrasive is injected to the surface
of the matrix.
[0010] Further, a mixing ratio of YSZ powder to
polytetrafluoroethylene powder is (92%-93%): (7%-8%), by mass
percent.
[0011] Further, drying refers to drying for 3 h at 50-90.degree.
C.
[0012] Further, a thickness of the like transfer membrane coating
is 20 .mu.m-40 .mu.m.
[0013] Further, the matrix is metal or ceramic material.
[0014] The present invention has the beneficial effects:
[0015] The wear resistance of the coating prepared by the method of
the present invention is significantly improved. The average
friction coefficient of the coating can be lowered to 0.1392. The
wear rate can be lowered to 8.434.times.10.sup.-6
mm.sup.3N.sup.-1m.sup.-1.
[0016] The coating prepared by the method of the present invention
has excellent corrosion resistance.
[0017] The coating prepared by the method of the present invention
has excellent superhydrophobic property.
[0018] By using the method of the present invention to prepare the
coating, during spraying, DC arc is generated between a cathode and
an anode, which heats and ionizes the introduced working gas into
high-temperature plasma and injects the plasma from a nozzle to
form plasma flame. The central temperature of the plasma flame can
reach 30000.degree. k. The temperature at an outlet of the nozzle
can reach 15000-20000.degree. k. The flame flow velocity at the
outlet of the nozzle can reach 1000-2000 m/s, but is attenuated
rapidly. Mixed powder is delivered by a powder feeder into flame
for melting, and after being accelerated by the flame flow to a
velocity greater than 150 m/s, the mixed powder is injected onto
the matrix material to form the coating. The high-temperature
plasma can completely melte PTFE and partially or completely melt
YSZ powder. Molten elements are solidified, which may impact the
surface of the coating together with the non-molten YSZ powder, and
a firm skeleton structure is formed to reinforce organic
components, so that primary materials are prevented from falling
off, and the coating with excellent cohesion may be formed on the
surface of the matrix.
[0019] The present invention adopts outer flames to feed the
powder, so that the PTFE components can be effectively prevented
from being burned out, and the YSZ particles can arrive at a
high-temperature zone under the effect of gravity to be molten
completely. The YSZ powder that does not enter the high-temperature
zone is kept at a particle state and has an impact effect on the
deposited coating under the effect of the plasma flame flow, so
that PTFE components in a liquid-phase zone are compacter and
smoother, thereby achieving a like transfer membrane structure.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] FIG. 1 is a schematic diagram of a preparation principle of
a like transfer membrane coating.
[0021] FIG. 2 shows a test result of morphology and hydrophobic
properties of surface interface and section structures of the
coating.
[0022] FIG. 3 is a section view of the coating, including the
coating;
[0023] FIG. 4 shows a test result of wear resistance, including
sliding time; friction coefficient; wear rate; samples; and
[0024] FIG. 5 shows a test result of corrosion resistance, wherein
on the horizontal axis, time is in Sec (second), and on the
longitudinal axis, E refers to level, and the unit is volts.
DETAILED DESCRIPTION OF THE PRESENT INVENTION
[0025] Embodiments are provided to better explain the content of
the present invention, and the content of the present invention is
not limited to the provided embodiments. Non-essential improvements
and adjustments made by those killed in the art for the
implementation solutions according to the content of the present
invention still fall within the protection scope of the present
invention.
Embodiment 1
[0026] A method for preparing a matrix protective coating includes
the following steps:
[0027] A, preprocessing, including:
[0028] a) Preparation of base materials: a 316 L stainless steel
workpiece with a dimension of .PHI.25 mm*6 mm is taken and ground
carefully with abrasive paper, and then burrs, welding slag, sharp
corners, etc. on the surface are removed.
[0029] b) Sand blasting: 0.3-0.4 MPa dry and clean compressed air
is used as power, under conditions that a spraying distance is 150
mm and an injection angle is 70.degree.-90.degree., multi-angular
granular 150-mesh white fused alumina abrasive is injected onto the
surface of a matrix at a high speed, so that surface impurities can
be cleaned thoroughly, and the surface is roughened to obtain a
preprocessed surface layer.
[0030] B, Preparation of a wear-resistant coating:
[0031] a) Mixed powder composed of zirconia-yttrium oxide powder,
i.e. YSZ powder (the content of yttrium oxide in the powder is 8 wt
%) and polytetrafluoroethylene powder (PTFE powder) in a ratio of
92% (YSZ): 8% (PTFE) is mixed uniformly by a rolling ball mill for
2 h, and then the mixed powder is dried in a drying box for 3 h at
50.degree. C. and then cooled to the room temperature.
[0032] B) The composite mixed powder cooled to the room temperature
is sprayed uniformly by an F4 spray gun onto the surface of a
preprocessed surface layer through a powder feeder by adopting an
atmospheric plasma spraying technology. Spraying parameters are set
as follows: the moving speed of the spray gun is 450 mm/s; the
current is 600 A, the voltage is 50Y, and power is 30 kW; the
compressed air is 0.6-0.7 MPa; powder feeding carrier gas Ar is 3
L/min; the powder feeding rate is 24 g/min; and the spraying
distance is 110 mm. After the spraying, a finished product can be
obtained, and the matrix does not need heat insulation and
heating.
[0033] A preparation principle of a like transfer membrane coating
is shown in FIG. 1.
[0034] It can be seen from FIG. 1 that YSZ powder and PTFE powder
are quite different in melting points. In the present embodiment,
the outer flame is used to feed the powder, so that the two
materials can be ensured to play good performance. The temperature
of the inner flame is far higher than the vaporization temperature
of PTFE, so there is no PTFE component in the high-temperature
zone. Although the outer flame is used to feed the powder, under
the effect of the gravity, part of YSZ may present in the central
high-temperature zone to reach a good molten state. When leaving
the high-temperature zone and reaching a low-temperature zone far
away from a muzzle, the powder may attain a relatively uniform
state. The well-molten YSZ components and PTFE components may be
deposited on the surface of the matrix. The YSZ forms a continuous
skeleton structure to fix the PTFE components, thereby preventing
primary materials from falling off. The non-molten YSZ has three
states: 1, the non-molten YSZ is deposited together with the
well-molten powder and fills the interior of the coating in a
particle state; 2, the non-molten YSZ adheres to the surface of the
coating; and 3, the non-molten YSZ is bounced off the surface of
the coating due to insufficient impact force, and does not adhere
to the coating, but plays a role in hammering and compacting the
surface of the coating.
[0035] Performance Test
[0036] A Zeiss-.SIGMA.IGMAHD field emission electronic microscope
is used to observe surface interface and sectional microstructures
of the coating and observe whether water drops can form a spherical
shape on the coating prepared in embodiment 1. Results are shown in
FIG. 2.
[0037] It can be seen from FIG. 2 that the surface of the coating
is relatively compact and has uniform bumps. However, the bums are
relatively small in size, so the surface is relatively smooth.
[0038] The molten YSZ has higher energy. The PTFE can obtain a wide
liquid-phase zone, so that the stress can be well released.
Meanwhile, the stacked coating suffers a low impact energy of the
non-molten particles continuously, so that the PTFE is hammed and
compacted continuously in a solidifying process. Therefore, the
coating has good compactness. The spraying angle is changed with
the movement of the muzzle, thereby generating a shelter effect.
Under the joint action of particle impact and shelter effect, the
surface structure that is relatively compact and smooth and has
uniform bumps is formed. This structure has some characteristics of
a transfer membrane to a certain extent and is referred to as a
like transfer membrane. This structure can be instantly transformed
into the transfer membrane under the effect of an external force.
The PTFE components make the coating surface have relatively low
surface energy. The micro-nano bumps on the surface of the coating
may trap air when the water drops are disposed to form a protective
air pad, so that the coating surface may not be wet. Therefore, the
superhydrophobic property is obtained (a water contact angle is
150.58.degree.). This proves that the coating of the present
invention has superhydrophobic property.
[0039] An MS-T3000 friction and wear test machine is used to test
friction and wear properties. A Gcr15 stainless steel ball friction
pair with a diameter of 6 mm is selected. Test parameters are set
as follows: the rotation speed is 200 rap/min; the rotation
diameter is 8 mm; the load is 5 N; and the friction test time is 90
min. Results are shown in FIG. 3.
[0040] It can be seen from FIG. 3 that a thickness of the coating
is about 20 .mu.m. The bump structure on the surface can be clearly
seen, which provides an evidence for the superhydrophobic
properties of the surface micro-nano structure of FIG. 1.
[0041] An ALPHASTEP D-100 step profiler is used to measure a
section contour of a grinding crack. Results are shown in FIG.
4.
[0042] It can be seen from FIG. 4 that the average friction
coefficient of the coating is 0.1392, and the wear rate is
8.434.times.10.sup.-6mm.sup.3N.sup.-1m.sup.-1. This proves that the
coating prepared by the method of the present invention has
excellent wear resistance. Under the load effect, the like transfer
membrane structure is instantly transformed into the transfer
membrane. The transfer membrane has the characteristics of surface
smoothness, continuity and toughness. Therefore, the friction
coefficient of the composite coating has a relatively low value.
The filler YSZ forms a firm skeleton structure in the coating, so
that not only are the PTFE components reinforced, but also the
primary materials are prevented from falling off (the poor bonding
property of the PTFE components severely limits the application
range; and the skeleton structure effectively strains the PTFE
components, so that the cohesion is effectively increased, and the
PTFE components can be prevented from falling off). Moreover, the
transfer membrane is reinforced and protected, so that secondary
materials can be prevented from falling off (the transfer membrane
formed by the PTFE components under the load effect is easy to fall
off, and the YSZ filler can obviously enhance the quality of the
transfer membrane and prevent under-surface damage and separate
fragments). During grinding-in, abrasive dust of the composite
coating is removed and compensated continuously; and after reaching
a transition point, a matching end surface is fully filled with
nano-scale fragments. These fragments exist continuously. The
abrasive surface of the composite coating becomes smooth and
compact, thereby guaranteeing the low friction coefficient and low
wear rate of the coating.
[0043] An electrochemical corrosion open-circuit potential curve is
tested by a CorrTestCS series electrochemical corrosion workstation
designed and manufactured by Wuhan Contest Instruments Co., Ltd.
Results are shown in FIG. 5.
[0044] It can be seen from FIG. 5 that the open-circuit potential
of the coating already becomes a positive value greater than 0
after 8000 s and continues to keep rising. The open-circuit
potential curve in FIG. 5 shows obvious fluctuation because
hydrophobic property of the coating forms a layer of dense bubble
barriers on the surface in a 3.5% NaCl solution environment and
breaks the bubbles under the action of potential. The open-circuit
potential is a positive value, so that the corrosion tendency of
the coating is greatly reduced. This proves that the coating of the
present invention has good corrosion resistance.
[0045] Furthermore, it should be understood that although this
specification is described according to the embodiments, each
embodiment does not include only one independent technical
solution. The description of the specification is only for the sake
of clarity. Those skilled in the art shall take the specification
as a whole, and the technical solutions in each embodiment can be
combined appropriately to form other embodiments that can be
understood by those skilled in the art.
* * * * *