mechanical and erosion properties of cac[o.sub.3]-emaa thermal sprayed coatings.

by:ZHENHUA     2020-09-01
Introduction polymer is a relatively common material in processing and production.
A processing technology that is increasingly used is thermal spraying.
Although the use of materials such as epoxy resin has been carried out for a period of time, the ability of thermal spray thermoplastic has become more and more popular and has opened up a range of potential materials that can be used, this is the subject of the recent extensive review (1).
As a coating technology, thermal spraying has many advantages because it can be used to coat a complex base shape without the need for a solvent that is otherwise eco-friendly (2-4).
The basic process of thermal spraying is simple ---
Using a carrier airflow, the fine particle direction of the polymer is pushed by heating the flame of the polymer (often heated)
They collide, press and assemble to form a coating base from the well-
Flat particles of adhesion (5).
Many spray techniques have been used, and the main difference is the heating source--
Oxygen from high speed-
Fuel Air plasma, vacuum plasma, traditional flame spray, air and (for example)
Propane forms a combustible mixture.
In this study, the flame spraying method was used, and the air was used to stream and transport powder from particles in the powder feeder (Or \"raw material \"(6)
In this field of technology, it is often called
It takes part in the torch that produces a burning flame.
The latter thermal spraying technology is the lowest and most physically portable technology in thermal plastic thermal spraying technology ---
A few hundred micrometers of polymer particles are needed.
The temperature of the flame itself is as high as 3000 [degrees]
Therefore, it is necessary for particles to cross the flame and be heated without suffering catastrophic molecular damage.
In fact, it has been shown that there is only a slight molecular weight change in the process of the usual use of interylene
(Acrylic)
Or related reunion)(7).
The main change is related to the increase in polarity caused by Polymer oxidation, which is advantageous because it encourages adhesion to polar metal substrates (8, 9).
Use of ethylene-polymer
Acrylic is of strategic significance because the acrylic/Poly composition is well combined with the metal base-
The ethylene plant provides moisture and other environmental resistance for the coating--
Make it very suitable for coating pipes, bridges, etc (10-13).
Although the process is simple, there are many variables that affect the integrity of the coating ---
In terms of stickiness and cohesion (14-16).
These include flame mixtures (temperature)
Speed of gas carrier, substrate temperature, torch crossing speed (
When the coating is applied), and so on (17-19).
Recently, we have found that this system can also be used in repair mode (20).
If certain parts of the coating should wear, break or fall off, it is determined that there is good adhesion between the newly sprayed molten polymer powder and the underlying old coating;
In fact, it is twice stronger than the original polymer. steel bond.
Interestingly, it is found that the binding between two related but different polymers is strongest (
Two kinds of polymer and monomer of ethylene-
Acrylic family)
, Compare polymer or polymer materials with themselves.
In many other areas of polymer science, the next
The generated material usually includes a combination of polymers with other materials, whether it is another polymer or some ceramic or metal phase, to form a composite material.
The composite has the advantages of maintaining toughness and coating
The forming properties of the plastic, while allowing the introduction of properties such as modification of modulus and wear resistance.
Another problem with the formation of thermal spray coatings is that for the thermal spray process, the raw material must have an appropriate particle size.
The ability to influence the above properties and other properties, such as surface polarity, results in the current effect on ethylene-
Acrylic polymer with calcium carbonate (a common inorganic filler) on the steel base.
Particle size is an important factor in determining the spraying and final performance of particles; therefore, CaC[O. sub. 3]
Three sizes are used for this work.
An important research area is the adhesion properties of the composite coating to the substrate, because not all inorganic particles pass through the flame and therefore do not melt, but are physically integrated into the coating.
Similarly, the bonding between the filler particles and the matrix material is the key to its integrity.
Therefore, a series of processing problems, as well as the final properties of the coating, were studied to determine the advantages and limitations of spraying mixtures of different material types.
The polymer used in this study is Ethylene Acrylic Acid (EMAA)copolymer (PF111U, 70 mesh;
Average diameter 140]micro]m)
Supplied by a plastic flame coating system (PFS, Texas). Three CaC[O. sub. 3]
Powder with different particle sizes is used as an inorganic additive.
The average particle size is 2. 8 [micro]m, 9 [micro]m, and 36 [micro]
Mi asdetermined uses Mike Saturn Digisizer 5200 (Micromeritics.
Norcross, Georgia).
Density of EMAA and CaC [O. sub. 3]
The gas ratio was determined to be 0. 9392 and 2. 697 g/[cm. sup. 3]
It is inconsistent with the established value of these materials. A blend of CaC[O. sub. 3]
EMAA is prepared by a mechanical mixing process in which the two powders are continuously combined and rolled in a cylindrical plastic container to ensure a uniform mixture.
The powder pistol from PFS 124 is used to preheat the coating and spray the coating. Propane (at 83 kPa)
Compressed air (at 207 kPa)
Used to produce a burning flame.
Compressed air is used to logistics the powder mix and deliver the powder mixture from the boiling bed to the torch, adding the burning gas to the torch to produce the flame.
The principle and process parameters of the plastic flame spraying system have been described before to deposit the EMAA coating (21, 22).
In this work, the final coating temperature is controlled by changing the number of passes of the torch during processing.
Measured the temperature of the sample by hand
Keep the infrared fire detector for a few seconds after spraying.
The substrate for stripping test is ordinary carbon steel (
190mm long, 25mm wide, 10mm high).
Clean the steel bar surface with acetone, but do not sandblasting before spraying.
The determination of the composition of the mixture and the composite coating observed that during the spraying process of the mechanical mixture, the higher density inorganic composition was not fully transferred to the coating.
In order to determine the loss of calcium carbonate filler, after 2 minutes of interval, in the absence of a flame, the mixture is transferred to the container through a flame spray lamp.
The density of the powder collected is determined by the gas specific bottle, as described below.
The density of the spraying material is used to calculate the composition of the mixture after spraying at different times.
Initial combination of three CaC [O. sub. 3]-
EMAA mixture of different packing sizes is 30vol %.
The filler content transferred to the final spray coating is also determined by the gas specific gravity method.
The deposition rate is determined as the volume of the thermal spray coating deposited within 10 minutes.
The deposition rate is then expressed as volume per minute.
The deposition efficiency is determined as the ratio of the powder mixture transmitted through the torch to the amount of material deposited in the coating.
Powder transported through the torch is obtained by collecting the powder in the re-barrier bag without flame.
The coating is obtained by flame around the powder mixture and deposited on apoly GmbH (PTFE)pan.
The coating is easy to remove after the spraying is completed.
Tensile and peel test tensile test samples are produced by spraying the coating on the aflat PTFE resin
It is easy to remove its coated substrate from it.
Then use the Astamping tool to form a dog bone-
Same sample, length 25mm, 3.
Width 5mm, thickness about 1mm.
Tensile Test on Instron 4505 (
Mechanical testing system
At high speed and room temperature of 50 mm/min, about 20 [degrees]C.
The amino groups of five samples were tested under each condition to evaluate the variability of the coating properties.
The modulus is automatically calculated using the cut-line modulus at 1% strain.
The yield stress is determined by stress. strain curve.
The tensile strength is defined as the maximum stress obtained from the curve.
Adhesion of a single coating to carbon steel (
Single layer configuration)
Or a coating deposited on a previously sprayed layer (
Double structure)
Use 90 [OK]degrees]peel test rig(ASTM 3167-97)(23).
The final coating thickness is about 1mm for single-layer samples and about 2mm for double-layer samples, because it was previously used to test the base and top layers of double-layer coatings (20).
The stripping test is carried out at a stripping speed on the inston 4505 mechanical testing system (Speed of Cross)of 50 mm/min.
At least five tests were conducted for each case. Density and X-
X-ray diffraction analysis to determine the density of powder and coating in AccuPyc1300 gas specific flask (Micromeritics)
Under the test conditions of five cleanups, 15 runs, all running at room temperature of 20 [degrees]C.
The powder used for analysis is simply poured into the sample cup, but the coating sprayed on the PTFEpan is removed and cut to be placed in a specific bottle.
Determination of phase composition and crystalline degree of powder and coating by rigorous X-ray diffraction vertical angle measuring instrument (Tokyo, Japan)
Set to 40 kV and 22 kV. 5 mA.
The detector is set to pass 1 of 20 ranges. 5[degrees]to 35[degrees]
The scanning rate is 1 [degrees]
/Min, the size of astep is 0. 05[degrees].
Erosion test and friction test (ASTM G76-95)(24)
Includes conveying metal pipes with an internal diameter of 6mm to the surface of the coating with compressed air.
The metal tube sets the angle of the eloden particle jet to 0 [degrees](horizontal)or 90[degrees](vertical).
The erodent used in this study is garnetwith 200 [micro]m to 600 [micro]m (30~60 mesh)particle size.
All erosion tests were carried out at 180g/min particle flux, 20 m/s particle velocity and about 20 [room temperature]degrees]C.
The cumulative erosion loss is measured by weighing the sample to 0 accuracy.
0001 grams every 5 minutes.
Friction and wear test (ASTMG 133-95)(25)
It was on the aDF. PM (Japan)
Reciprocating sliding friction tester under 1 N or 3 N load friction conditions with a speed of 90mm/min, a stroke of 5mm and a room temperature of 18 [degrees]
Relative humidity of total circulation of C, 37% and 200.
The corresponding ball is bearing steel (SAE 52100)of3-mm diameter.
In this work, the wear trace width measured by a digital recording microscope was used to determine the wear behavior of the composite coating.
SEM observation surface image and fracture cross section of polymer coating were observed on jeol jsm-
840A scanning microscope (Tokyo, Japan).
Prevent plastic deformation of polymer coating at normal temperature.
At the temperature of liquid nitrogen, the SEM sample broke and the gold sputtering
There are 12 short cycles painted, each by a10-
Second coating time and 10-
The second break
During the observation, the acceleration voltage of 15kv was used in SEM.
Composition of the results and discussions of CaC [O. sub. 3]-
The EMAA coating has previously been determined that in the case of the use of a mechanical powder mixture, the composition of the thermal spray composite coating is different from the powder mixture used for spraying (26).
Usually, the amount of heavier filler in the final coating is less than the amount in the powder mixture.
The source of the loss of the filler is considered to be mainly attributable to the difference in morphology, density and size of the filler and polymer powder, and there is no knowledge of the main factors affecting the loss of the filler.
In order to better understand the loss of the filler, it is necessary to track the changes in the composition of the mixture during the spray process.
In this work, the packing loss and dynamics of three different size filler particles were studied.
These are shipped to the collection ship (plastic bag)
In the absence of flames, changes in composition can be monitored over time.
Each powder mixture shows a different CaC [loss]O. sub. 3]
Powder, the degree of loss depends on the size of the filler, as shown in the figure1.
The initial concentration is 30 volume % in all cases.
The powder with the largest inorganic filler has the least loss during powder transportation and produces a relatively constant 25 Volume % inorganic filler within 40 minutes.
Samples containing smaller filler sizes resulted in a decrease in filler content after 2 minutes and greater loss over time.
The minimum filler size mixed with polymer powder produces almost two
The loss in the filler, initially reached 18 volume %, reduced to 10 volume % after 40 minutes.
Some errors in density measurement may be caused by the attraction of CaC [O. sub. 3]
Filling of plastic bags.
However, the results reflect the trend of the composition of the mixture.
The transport of mixed polymers and inorganic powders indicates that a portion of the fine inorganic particles is lost, the lighter particles become more uniform, and the larger, heavier particles are lost 36-[micro]
Polymer powder transfers m particles more effectively. [
Figure 1 slightly]
By checking the fluidized bed powder feeder, it was found that the trend of lower packing transfer was the same.
Occasionally, some filler powders adhere to the inner wall of the fluidized bed powder bucket wall.
The density of the powder accumulated on the inner wall of the boiling bed above the top powder level is higher than the initial powder mixture placed in the powder feeder.
This indicates a high filling content on the inner wall of the feeder.
Small inorganic filler particles with lower weight seem to preferably relocate on the wall of the barrel.
For example, the initial combination of CaC [O. sub. 3]-
EMAA powder and 9-[micro]
The M-grade powder is 30 volume %, but after 30 minutes of powder transportation, the filler content of the transported powder is 16 volume %, while the mixture remaining in the boiling bed is 20 volume %.
However, the powder collected on the wall of the barrel reached a filling amount of up to 46 volume %.
Therefore, the individual filler particles are too light to fully coordinate
Flow of plastic particles.
Therefore, when the filler is mixed with plastic particles, the closer the weight of the filler particles is to the plastic particles, the better the streaming effect of the two powder types in the mixture.
For the EMAA powder used in this study, the average particle size is 40 [micro]
M, average weight-
The particle size is 1. 35 X[10. sup. -6]g.
Average weight of a single CaC [O. sub. 3]
Fillerparticle is month. 10 X [10. sup. -11]g, 1. 03 X [10. sup. -9]g, and 0. 66 X[10. sup. -7]
G of filler with an average particle size of 3, 9 and 36 [micro]
It\'s m, and all the particles are much lighter than the emaa particles.
In order to match this mass, the average size of the inorganic filler must be much larger ,~ 99 [micro]m.
Note that the rounded shape of the filler also provides less buoyancy compared to polymer particles, and reduces the optimal size slightly accordingly.
During the deposition process, additional filler is lost when the material is fed through the flame through the composite material. Fig. 2.
In the fluidized bed powder feeder, the filler in the powder mixture is increased, resulting in a linear increase in the filler added to the coating.
The Alarger filler size creates a steeper gradient on the production line, which indicates that the filler loss is lower during the spraying process.
The high filling loss of small and medium particles during deposition is attributed to the on-board filling loss and rebound from the substrate.
Due to the high particle softness caused by the heating process, the polymer has higher momentum and effective deposition.
The addition of hard filler particles mainly depends on the softness of the lower surface.
The small size is more sensitive to the airflow, approaching the substrate at right angles, but changes occur on the substrate to follow the substrate surface.
It is expected that very small particles will be carried in the gas flow path and may not be able to reach the soft polymer surface and be taken away as part of the wastewater.
It is found that the addition of the filler will affect the coating deposition rate.
In order to keep the filler content about 6 volume % in the coating of all composite coatings, the powder mixture was prepared using the data from Figure 12.
To achieve this, a powder mixture was prepared with a filler of 20, 25 and 30 volume %, with filler particles sizes of 36, 9 and 3 [micro]M respectively.
The deposition rate of various powder mixtures was measured, as shown in Table 1, the amount of coating deposited per unit of time.
The deposition rate decreases with the addition of organic fillers (
Not surprising because of the loss of inorganic particles).
It seems that the addition of a 6 volume % filler to the coating does not comply with the rules of the mixture, and since the deposition rate of the polymer is 94 Volume %, the polymer deposition rate will be reduced by 26% to 24.
4%, the actual decrease in total solid content was 36-21%[micro]
The M filler and 10% are 2. 8-[micro]m filler.
The deposition rate decreases as the size of the filler particles decreases, as smaller particles are more likely to disappear from the substrate-
As mentioned above.
Deposition efficiency (Table 2)
It is a combination of the deposition rate and rate of the substance leaving the boiling bed.
When the filler content in the coating remains at about 6vol %, the deposition efficiency shows the same trend as the deposition rate. Table 2.
As mentioned above, pure PF111 has a deposition efficiency of up to 90%, while the mixed powder shows a lower deposition associated with the size and content of the filled particles. [
Figure 2:X-
The effect of the addition of the filler on the crystal of the matrix was monitored by X-ray diffraction.
The mixture of filler and powder shows the diffraction peaks for both components, but a new peak appears, most likely related to polymer phase.
Diffraction patterns of fillers, polymer powders and coatings are shown in the figure. 3a.
In the composite coating, the new peak is 23. 0[degrees]and 29. 4[degrees]
Because of the filling. Fig. 3b.
A small peak of 23. 0[degrees]
Due to the larger crystal size, the particle size with the larger filler becomes more clear.
The ratio of the Crystal Peak is 21. 2[degrees]
Despite the presence of fillers, the height from polymer to non-crystalline peaks remains unchanged.
The new peak is at 18. 6[degrees]
, This may be due to the influence of calcium carbonate particles encouraging the shape and nucleus of different polymer crystal structures.
Surface of CaC [O. sub. 3]-
As observed by the scanning electron microscope, the EMAA composite coating is still very smooth, the typical thermal spray polymer coating, although it contains the filling particles that are loosely adhered to the surface, fig. 4a.
The filler is more clearly observed on the cross section of the fracture, as a rough area within the coating, fig. 4b.
The fault occurred near the filler particles.
It is not clear whether the polymer between different filler particles provides a minimum resistance path through the material.
The rough appearance of the failure surface indicates that failure can cause the polymer to disengage from the filler particles. [
Figure 3 slightly]
The tensile and peel strength of the composite coating with the change in the mechanical behavior of the filler added to the neatPF111 polymer significantly results in a significant reduction in the tensile and tensile strength of the coating. Table 2.
With the increase of filler content, the 1% cut-line modulus of the composite material increases slightly.
It is well known that the addition of inorganic fillers to the polymer matrix increases its modulus and hardness and reduces the scalability of the polymer.
Strain fracture and tensile strength of pure PF111 were 512% and 12, respectively.
6 MPa, while the content of the filler is 7.
25%, these properties are only 48% and 10. 4 MPa. The filler-
The enriched boundary region of polymer particles deposited in thermal spray coatings results in a significant reduction in mechanical properties compared to compressed-formed composites.
The filling particles in the coating are not evenly distributed as they are when compressed
Molded samples, but are expected to be limited to the outer perimeter of each flat polymer particle.
Filler particles are considered to be deposited on hot polymers to flatten the particles and spread through the heat dissipation of the coating to the periphery of the polymer area during the melting drop deposition process.
This diffusion is supported by a lower molecular weight of the polymer chain in the outer layer of the polymer particles, due to the strong heating conditions exposed to the Flame (7).
In addition, the high heat capacity of the inorganic filler particles promotes diffusion because heat is released during the cooling of the filler particles.
As the filler interacts with a cooled flat polymer core containing a high molecular weight EMAA, the degree of diffusion will decrease.
So a contribution is as small as 2.
5 voln leads to a large change in microstructure, resulting in a significant reduction in fracture elongation. [
Figure 4 slightly]
The exact modulus, hardness and scalability of the coating are expected to be uneven across the entire samplelevel.
In the deposited polymer particles, the modulus and hardness are reduced and the scalability is increased.
The total deformation within these particles will affect the surrounding particles-
Rich areas with high modulus and hardness
If the total deformation applied is too large, the toughness area that may break.
The effect of filler size of various filler particle sizes on the tensile properties of the 5 volume % filler composite coating was determined. Table 3.
All tensile curves show the same shape, except that the scalability of the composite with large particles is slightly lower, which may be due to the greater possibility of weakness in the mixture.
As for the tensile properties of the flame
Effects of spraying composite materials and fillers on the peel strength of steel (
Or any substrate)
No reports have yet been reported.
Composite coating peel strength curves of different packing sizes.
The filling content is about 5 volume %, as shown in the figure5. The 2. 8-[micro]
M-filled composites reach their maximum peel strength earlier in the extension part of the test, while thel-
Ceramic particles-
The filling material shows earlier positioning.
The low initial peel strength may be due to a slightly higher filler content.
With the increase of packing size, there is no significant change in peel strength, providing a value of 1. 46 [+ or -]0. 36, 1. 37 [+ or -]0. 41 and 1. 29 [+ or -]0. 27 N/m. [
Figure 5 Slightly]
Influence of filler content (
In the case of 9-[micro]m powder)
To reduce the adhesive strength and failure strain, fig. 6.
Peel strength of PF111, 2. 54%, 5. 46% and 7.
The packing is determined to be 25%. 2 [+ or -]0. 76, 1. 54 [+ or -]0. 56, 1. 23 [+ or -]0. 41, and 0. 94 [+or -]0.
33 N/m, respectively.
The lower bond strength is attributed to the smaller interaction between the polymer and the substrate.
The filler does not adhere to the substrate like a polymer.
Prevents the interaction between the polymer and the underlying metal substrate.
The observation of the peeling surface showed that some uncovered filler particles were exposed on the sample surface.
There\'s one without these.
As shown in the figure, the sliding phenomenon in the pure plastic coating6.
Stripping the stability of the composite coating creates a smooth fracture surface, as shown in the figure7.
Comparison between graphs5 and Fig.
It is also shown that preheating temperature is an important parameter that affects the adhesion between the coating and the substrate.
The peel strength decreases from about 1 N/mm at a preheated temperature of 100 [degrees]C to 0.
7 N/mm with preheating temperature of 60 [degrees]C.
For pure PF111 coatings, a higher preheating temperature is required to obtain a stronger coating/substrate adhesion (20).
2-layer coating PF111 onCaC [O. sub. 3]-
PF111 was then prepared by thermal spraying to study the adhesion between the composite coating and the pure polymer coating.
The PF111 coating is used as a place for the top layer.
The peel strength of the neatlayer sprayed on the composite decreases with the increase of the filling amount, fig. 8.
This reduction is similar to the decrease in peel strength of a single layer composite coating on the steel body, as shown in the figure6.
Peel strength between PF111 and CaC [O. sub. 3]-
PF111 inside thedouble-
Coating is higher than the coating between CaC [O. sub. 3]-
Between the PF111 single layer and the substrate, even higher than the peel strength between the PF111 individual and the substrate.
Therefore, the addition of an intermediate polymer coating can improve the bonding between the polymer composite coating and the substrate.
The stripping test reveals many \"welding points \"(20).
These points result in higher peel strength of the double coat.
The PF111 double coat on the PF111 composite also shows the welding point on the peeling surface, but the density of the welding point may be lower than the PF111 on the PF111 double coat, reduced by the presence of inorganic particles, figure9.
Although most filler particles are completely covered by polymers, thin polymer coatings on organic particles can be seen in Figure 1
It is easy to peel off to expose the filler particles. [
Figure 6 slightly][
Figure 7 Slightly][
Figure 8:[
Figure 9 omitted
Erosion and friction behavior of composite coatings erosion and wear properties of flame
Spraying polymer coatings has not been widely reported in the literature.
The widespread use of these anti-corrosion coatings has exposed them to mechanical abuse.
The most common erosion environment (27, 28).
Recent workSprayed alumina-
Enhanced nylon coating reveals the improvement of corrosion resistance at low particle speed (29).
At the impact angle of 45 [, material loss in composite coatings with different filling sizes but similar filling volume fractions was studieddegrees].
Figure 10 shows the cumulative volume loss of coatings of different packing sizes due to erosion.
Although the minimum amount of filler content for all composite coatings is low, the minimum amount of filler appears to produce the best corrosion resistance.
It is worth noting that the coating using the minimum filling size is the only one that is more wear-resistant
Than the coating of the polymer itself.
The increase in resistance may be related to a more uniform coating at the micron level, which increases the effective hardness of the coating. [
Figure 10 slightly]
The erosion volume loss of the system by the composite coating with different filling amount was also determined;
The results are shown in the figure. 11.
The increase in filler content in the coating creates a higher material volume loss through erosion.
Erosion is considered to be a complex process related to fatigue, friction behavior, and matrix mechanical properties.
Any reduction in matrix extensibility will result in a decrease in fatigue resistance.
This is harmful to atrix\'s ability to resist erosion.
For materials showing awell, the increase in hardness should
The microstructure of bonded composite materials is conducive to enhancing the erosion resistance of the matrix (30).
These opposite factors coexist in the composite.
When the filler content is low, the effect of hardness will dominate the erosion resistance of the matrix.
When the filler content is high, the reverse effect of fatigue becomes more prominent (31).
The cumulative erosion volume loss of the coating decreased significantly from the [45] angle changedegrees]to90[degrees], Fig. 12.
Carbon steel has the same behavior (32)
It is explained by many aspects of material friction behavior.
Under normal friction conditions, the wear resistance of PF111 is much lower than that of metal.
Since fatigue and wear resistance are two important factors of material erosion resistance, the influence of these two factors will be weakened with the change of angle.
Fatigue resistance is the decisive factor of vertical impact.
With the decrease of the impact angle, the influence of wear resistance becomes the decisive factor (33, 34).
PF111 polymer has poor wear resistance at low impact angle, so the loss of erosion volume is very significant. [
Figure 11 omitted][
Figure 12:
Erosion resistance is also related to other friction properties of the composite coating.
The friction coefficient and wear trajectory width of the composite coating decrease with the increase of the filler content, fig. 13.
This smaller track width indicates that the addition of the filler improves the wear resistance of the polymerization coating.
The wear marks were examined by scanning electron microscopy and serious plastic deformation of the PF111 coating was found. Fig. 14a.
The low deformation of the neat PF111 does not support the load added by the ballon-
The structure of the plate, resulting in high wear and friction coefficient. Inclusion of 2. 54% CaC[O. sub. 3]
In the coating, it is shown that the plastic deformation is small, indicating that the hardness of the coating is improved. 14b.
The ribbon appearance of the edge of the wear marks means that the toughness remains.
Increase the filler content to 7.
Figure 25% shows no visible plastic defects. 14c.
A slight scratch on the surface reveals areas of the separated particles in the patch that may represent a collection of particles and lead to a reduction in plastic deformation. [
Figure 13:
According to the packing load, the microscopic photos of erosion scars show different surfaces. Fig. 15.
Scars on pure pf111 show ripples representing the erosion process of plastic materials, fig. 15a.
Ripples are caused by the plastic deformation capacity of the polymer, which is a response to the force applied by erodentparticles.
In addition, it is easier to capture a large number of particles in the coating.
In the coating containing the filler, many cracks become visible (Fig. 15b)
, This is due to the reduced scalability as the filler is added.
The fatigue resistance and strain of polymer coatings with fillers are reduced at the same time.
As the filler produces more strain, the coating is damaged, and the large erosion debris leaves the surface in the form of debris
Sensitive areas within the coating. Fig. 15c. The strain-
The sensitive area will be formed around the inorganic filler because the inorganic filler cannot be easily deformed compared to the polymer matrix.
Therefore, the erosion process is considered to be a periodic compression deformation process caused by the influence of the erodent flux (35).
The results show that mechanical properties such as elastic modulus, hardness, etc.
The friction coefficient and erosion resistance can be improved;
However, composite coatings made of mechanical mixed fillers and polymer powders appear to be sensitive to the size and content of the fillers.
This behavior is attributed to the localization of filler particles between and within the boundaries of the deposited aggregate particles, in which case the high filler concentration is quickly established.
Further work is needed to study the mechanical properties of a composite coating that uses larger than the filler particles used here, and can flow to the same extent as polymer particles, and it is likely that different microstructure will be established in the composite.
Larger filler particles can change the extrusion of particles from the composite material, thus changing the resistance to erosion (36).
The distribution of this microstructure is expected to be more uniform.
Due to the higher momentum of the filler particles, the soft polymer surface can be embedded more effectively.
The fracture toughness of these coatings will be of further interest.
This property can also be used to calculate the ratio of brittle index, hardness to fracture toughness, which was found to provide a good indicator for the erosion resistance of polymer materials (37).
While the mechanical powder mixture reported in this work provides a way to combine different materials into the spraying material, it should be noted that another potential method for producing the composite material (
Never learned here)
Includes mechanically combining the two materials into each Powder Particle (38).
The powder cost is higher due to the additional cost of powder processing, but can provide higher deposition efficiency.
And ensure that the content of inorganic components is uniform.
One way to combine inorganic materials with Polymer raw materials is mechanical melting.
Previous work shows the stratification of inorganic materials on polymer particles (39).
However, it should be noted that due to the different distribution of unorganized particles in the coating, the results microstructure of mechanical alloys and mechanical powders may be different. [
Figure 14 omitted][
Figure 15 omitted]
Conclusion The Inorganic filler content in the mechanical mixed powder transported by the flame spray lamp through the fluidized bed powder feeder decreases over a period of time.
For finer particles, this reduction is greater because of the different flow properties within the feeder and in the flame fast airflow.
With the increase of filler content in the powder mixture, the deposition rate and efficiency are reduced.
The maximum packing transport properties, deposition efficiency and deposition rate are obtained (36-[micro]m)CaC[O. sub. 3]filler used.
The packing size has no significant effect on the overall tensile properties and peel strength of the coating.
The influence of the filler content is greater, reducing the tensile strain at the time of fracture, but increasing the modulus.
The peel strength of single-layer and double-layer coatings decreases with the increase of filling volume.
However, the adhesion between the composite coating and the pure polymer is significantly higher than that of the composite coating on carbon steel.
Therefore, with the presence of a pure PF111 coating as a bonding layer, the use of the composite coating is enhanced.
When the filler is added in 5 volume %, the filler size also has little effect on the erosion of the composite.
However, the filler content greater than 5vol % will produce a coating with lower erosion resistance than the apure PF111 coating.
At the angle of 90 [degrees]
Fatigue resistance dominates, while fatigue resistance plays a more important role at a lower angle of attack.
Although the efficiency of friction decreases as the filler load increases, when the filler load exceeds 5 volume %, the mechanical properties of the composite are undesirable for erosion.
In general, low filler loads can increase the hardness, modulus and corrosion resistance at the same time.
The authors appreciate the nsf int 9513462, which makes this work possible. Dr. F. Y.
Supported by the National Natural Science Foundation
National Natural Science Foundation of China)
Grant 59925513 and Dr. K. A.
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Cleveland ASM International (1994). F. Y. YAN (1,2), K. A. GROSS (1*), G. P. SIMON (1), and C. C. BERNDT (3)(1)
VIC 3800, School of Physics and Materials Engineering, Monash University, Australia (2)
State Key Laboratory of solid lubrication Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, China (3)
Department of Materials Science and Engineering, Stony Brook University, New York, NY 11794-
2275 * who should be communicated.
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