HVAF vs. HVOF WCCoCr
10-06-2016, 03:52 PM,
#1
Lightbulb  HVAF vs. HVOF WCCoCr

Kermetico Inc claims here that its AK-series HVAF equipment reached WCCoCr coating quality of 1450-1700 HV300 hardness, less than 0,3% porosity, no cracking (ductile). Kermetico even posted a YouTube video showing the HVAF-sprayed carbide tool for turning.
VTT, Finland as well as other researchers support these claims with their academic papers.
That coating quality definitely means huge new market possibilities for the WCCoCr thermal spray applications, but somehow it is not widely accepted by the industry yet.
What is it? Inertia or underestimation?

Please, share your thoughts.
Vig
Reply
10-06-2016, 06:22 PM,
#2
RE: HVAF vs. HVOF WCCoCr
(10-06-2016, 03:52 PM)Vig Wrote: Kermetico Inc claims here that its AK-series HVAF equipment reached WCCoCr coating quality of 1450-1700 HV300 hardness, less than 0,3% porosity, no cracking (ductile). Kermetico even posted a YouTube video showing the HVAF-sprayed carbide tool for turning.
VTT, Finland as well as other researchers support these claims with their academic papers.
That coating quality definitely means huge new market possibilities for the WCCoCr thermal spray applications, but somehow it is not widely accepted by the industry yet.
What is it? Inertia or underestimation?

Please, share your thoughts.
Vig

Hi Vig,
It is not so clear with the HVAF-coatings WC-Co-Cr. What does mean ductile behavior for a brittle material that is not plastically deformable? The ductile behavior of WC-Co-Cr layers has only one explanation: the connections between individual particles are very weak (low cohesion)! This also means that the modulus of elasticity and the strength of such a layer must be low. Low modulus of elasticity explains the advantages of the HVAF layers in the case of thermal shock resistance and possible large layer thickness, which otherwise can not be achieved with HVOF. On the other hand, poor cohesion means that the layer must be less wear- and corrosion-resistant.
Regards
Vadim
Reply
10-06-2016, 07:40 PM,
#3
RE: HVAF vs. HVOF WCCoCr
Hi, Vadim

Thank you for your thought.

There is one more explanation.
What makes sprayed WC-Co-Cr that brittle? W2C, which is present in HVOF coatings and absent in HVAF.
May this lack of W2C be a reason for high ductility?
Check this ITSC-2015 presentation, and you will find that HVAF modulus of elasticity is ... 1,5 higher than HVOF's!
Which leads to much better cavitation and erosion test results.

Could you imagine poor wear- or corrosion resistance of the coating with the micro-cuts you can see at the link I shared in the first post?
And believe me, they are not unique picks.
My last company used Kermetico equipment for 10+ years, so I haven't just heard it on the grapevine.

BR,
Vig
Reply
10-07-2016, 05:43 AM,
#4
RE: HVAF vs. HVOF WCCoCr
Vig,

In my opinion its mostly inertia in the market, moving along the path of HVOF for the last many years. To overcome the inertia will take some champions in the industry, especially those USA or European OEMs to give it acceptance in production. If the cost per mm2 of WCCoCr can drop, the usage will dramatically increase. The powder suppliers and manufacturers of carbides should support the promotion of HVAF coatings.

Its a classic case of the better product struggling to overcome this inertia. Thats looking a from the equipment maker point of view.

However from a user point of view, HVAF can be an incredible advantage compared to other systems used by competitive shops....right?





Stephen James Booth
www.ipsteknokraft.com
www.teknokraft.com
Indonesia WhatsApp +6281905603262

Reply
10-07-2016, 09:35 AM, (This post was last modified: 10-07-2016, 02:31 PM by Vadim Verlotski.)
#5
RE: HVAF vs. HVOF WCCoCr
(10-06-2016, 07:40 PM)Vig Wrote: Hi, Vadim

Thank you for your thought.

There is one more explanation.
What makes sprayed WC-Co-Cr that brittle? W2C, which is present in HVOF coatings and absent in HVAF.
May this lack of W2C be a reason for high ductility?
Check this ITSC-2015 presentation, and you will find that HVAF modulus of elasticity is ... 1,5 higher than HVOF's!
Which leads to much better cavitation and erosion test results.

Could you imagine poor wear- or corrosion resistance of the coating with the micro-cuts you can see at the link I shared in the first post?
And believe me, they are not unique picks.
My last company used Kermetico equipment for 10+ years, so I haven't just heard it on the grapevine.

BR,
Vig

Hi Vig,

In my opinion is the micro-indentation technique for determination of Young’s Modulus absolutely not applicable to the all of spraying layers. In this technique, modulus of elasticity is determined for individual grains in the material, but not for the entire layer, which has other phases, grain boundaries, cracks, pores, and other defects. In reality, no coating layers have Young’s Modulus greater than 300 GPa, otherwise they would not have retained on the steel substrate.
A layer of WC-Co-Cr has a very low thermal expansion coefficient (about 5x10-6K-1). The difference with the steel substrate is greater than 6x10-6K-1 and therefore the layer gets very high mechanical stresses during heating and cooling. If such a layer had the modulus of elasticity above 200 GPa, it would already have peeled off yet at 100°C temperature difference.
Since the real WC-Co-Cr layers can withstand more than 250°C temperature difference, it proves that the all must have Young’s Modulus only about 100-150 GPa. Thick layers which can withstand 350°C warm-up have a modulus of elasticity between 50 and 100 GPa, which means a weak cohesion.

One can not have everything at the same time: high modulus of elasticity (also means high strength, hardness and wear resistance) together with high ductility (also means bigness, great thickness, thermal shock resistance, high temperature application and other).

BR
Vadim
Reply
10-08-2016, 06:33 AM,
#6
RE: HVAF vs. HVOF WCCoCr
(10-07-2016, 09:35 AM)Vadim Verlotski Wrote:
(10-06-2016, 07:40 PM)Vig Wrote: Hi, Vadim

Thank you for your thought.

There is one more explanation.
What makes sprayed WC-Co-Cr that brittle? W2C, which is present in HVOF coatings and absent in HVAF.
May this lack of W2C be a reason for high ductility?
Check this ITSC-2015 presentation, and you will find that HVAF modulus of elasticity is ... 1,5 higher than HVOF's!
Which leads to much better cavitation and erosion test results.

Could you imagine poor wear- or corrosion resistance of the coating with the micro-cuts you can see at the link I shared in the first post?
And believe me, they are not unique picks.
My last company used Kermetico equipment for 10+ years, so I haven't just heard it on the grapevine.

BR,
Vig

Hi Vig,

In my opinion is the micro-indentation technique for determination of Young’s Modulus absolutely not applicable to the all of spraying layers. In this technique, modulus of elasticity is determined for individual grains in the material, but not for the entire layer, which has other phases, grain boundaries, cracks, pores, and other defects. In reality, no coating layers have Young’s Modulus greater than 300 GPa, otherwise they would not have retained on the steel substrate.
A layer of WC-Co-Cr has a very low thermal expansion coefficient (about 5x10-6K-1). The difference with the steel substrate is greater than 6x10-6K-1 and therefore the layer gets very high mechanical stresses during heating and cooling. If such a layer had the modulus of elasticity above 200 GPa, it would already have peeled off yet at 100°C temperature difference.
Since the real WC-Co-Cr layers can withstand more than 250°C temperature difference, it proves that the all must have Young’s Modulus only about 100-150 GPa. Thick layers which can withstand 350°C warm-up have a modulus of elasticity between 50 and 100 GPa, which means a weak cohesion.

One can not have everything at the same time: high modulus of elasticity (also means high strength, hardness and wear resistance) together with high ductility (also means bigness, great thickness, thermal shock resistance, high temperature application and other).

BR
Vadim

Vadim,
I respectfully disagree with majority of your statements.

1) The WC-10Co-4Cr material has no ductility

The WC-10Co-4Cr has 14 wt.% of Co-Cr metal alloy in it, or about 23 vol.%. Well, this alloy is pretty much ductile. Thus, the composite materials itself is ductile. Even if you saturated it with oxygen during HVOF spraying. And even when you dissolved tungsten and carbon in it. Still ductile. The HVAF coating is just more ductile, because of rate of oxidation and decarburization in the process is substantially lower. By the way, WC mono-carbide has some ductility. Contrary to W2C and majority of other carbides and borides.

2) Young modulus measurements technique is "false"

a) Microindentation is performed at loads 1 kg, 2 kg and even10 kg loads. At 1 kg load the indentation diagonal is about 40-50 micron. We are using WC-Co-Cr average particle size below 20 micron. And each particle deforms when forming the coating. Thus, with 1 kg indentation one is covering not individual grains, but several particles in the coating. Thus, 400 GPa modulus "belongs" to the coating.
b) The team from Indian Power Research Institute (Bangalore) was using "scratching technique" for modulus determination, getting 420-460 GPa for different AK-HVAF coatings and about 260 GPa for HVOF ones. Well, scratching through the whole coating thickness. And in different directions. So much for individual grains.

3) Stresses formation during coating deposition should destroy the coating with high modulus of elasticity

You are confusing cooling of the whole coating layer versus substrate AND stresses appearance and buildup during the coating formation which involves cooling of separate particles. And you completely ignore the impact of other particles, including those which did not deposit during spraying. Evidently, at DE 50% half of them strike the surface and bounce back.

Each particle cools down to the surface temperature individually, before next particle strikes it. The particle already formed the bonds to the substrate at higher temperature - somewhere in between the melting temperature of Co-Cr alloy and 1000 deg.C or so. Yes, CTE for the particle is lower than for the substrate, but it formed the bonds at above 1000 deg.C. The substrate was heated to "spray spot" surface temperature only - surely not above 400 deg. C. This minimizes the "shrinkage difference". But does not eliminates it completely.

The remaining "shrinkage difference" creates stresses between the particle and the substrate. Those stresses are substantially relived by plastic deformation and by micro-cracking, i.e. destruction of already formed bonds (yes, it's unavoidable). But the stress relieve requires some time. And here comes "handy" the impact of the next particle, which strikes but may or may not bond. This impact further affects stresses in the particle. Remaining "mismatch" results in formation of residual stresses between the sprayed particle and the substrate (let's call it "Type 1" stresses).

The Type 1 stresses accumulate in the layer, deposited per pass ("Type 2"). And Type 2 stresses from each layer accumulate in the coating, forming its final residual stresses field ("Type 3"). In fact, in all stages this is not just "sum of stresses". Type 1 is changing while the spray layer is formed; and Type 2 in previous layers is changing while applying new layers.
The point is that the structure of the coating is "frozen" at some elevated temperature. If this temperature is found correctly (job for a technology developer), the coating stays. If not - it cracks and/or delaminates.

In such scenario I do not see a direct correlation of cracking and Young modulus. Yes, stresses will be higher in the materials with higher Young modulus. But the cohesion strength will also be higher for such materials.

4) Stresses during heating should destroy the coating with high modulus

Again, the coating accumulate residual stresses (Type 3) at elevated temperature. When you start heating the coating, first thing you would see is a reduction of residual stresses. And only further heating would start building the stresses related to the thermal expansion mismatch between the coating and the substrate. And here comes at play the coating ductility. To the limited extend. Then cracking occurs.

Actually, during thermal cycling the carbide coatings usually crack. The issue is what kind of cracking it is. If cracks are isolated on "micro-level", the coating stays on the substrate and does its job. If micro-cracking results in macro-cracking - the coating fails. The same is true for cycling mechanical loads.

Again, it is more about coating thickness, coating structure and ductility rather then Young modulus.

5) Building of thick layers in HVAF as an evidence of "weakness"

The pinning effect of blasting particles during HVAF spraying is stronger than in HVOF (lower temperature of particles and higher velocity). The direct confirmation of this is that compressive residual stresses in HVAF are higher than in HVOF. Substantially. This is why a thicker layer per pass and a thicker total coating is possible to apply with HVAF. Not because it is "weak" material.

I do not see any logic in calling the same material weaker, when it has higher hardness, higher K1C and higher Young modulus.

Furthermore,there are publication and reports, directly comparing AK-HVAF WC-10C04Cr versus HVOF counterparts (JP5000, DJ2600, K2). The AK-HVAF improvements in testing:
a) Rubber Wheel test, Miller test, Pin-on-Disc test: 1.5-2.0 times
b) Silt erosion and dry erosion: 5+ times
c) Cavitation: 10+ times

I strongly agree with one statement: In the WC-10Co-4Cr coatings (like in majority of others), there are areas between sprayed particles without bonds - voids, micro-cracks, etc. It seems though, there are less of those in the HVAF carbide coatings .

And final remark, related to ductility (I think). In erosion test the WC-10Co-4Cr AK-HVAF coatings performed better at 90 degree angle of attack as compared to 30 degree angle. Data from several sources already. Explain this without using term "ductility".

One can't have it all. But one can have more with HVAF carbides.

Regards,
Andrew Verstak
Kermetico Inc.


Reply
10-08-2016, 04:29 PM, (This post was last modified: 10-08-2016, 04:42 PM by Vig.)
#7
RE: HVAF vs. HVOF WCCoCr
(10-07-2016, 05:43 AM)Stephen Booth Wrote: Vig,

In my opinion its mostly inertia in the market, moving along the path of HVOF for the last many years. To overcome the inertia will take some champions in the industry, especially those USA or European OEMs to give it acceptance in production. If the cost per mm2 of WCCoCr can drop, the usage will dramatically increase. The powder suppliers and manufacturers of carbides should support the promotion of HVAF coatings.

Its a classic case of the better product struggling to overcome this inertia. Thats looking a from the equipment maker point of view.

However from a user point of view, HVAF can be an incredible advantage compared to other systems used by competitive shops....right?

Stephen,

Cost per mm2 of WCCoCr is twice less for HVAF in comparison with industry standard HVOF.Smile
I completely agree with your point that HVAF technology is quite underestimated by powder manufacturers. Well, I understand the big guys, which market HVOF equipment as well as powders, but why "pure" powder manufacturers, like H.C. Starck or C&M are in the shadowQuestion It is their chance to substantially improve their market positions with this rapidly growing HVAF segment.
Well, it looks like another opportunity for East Asian foundries.

BR,
Vig

(10-08-2016, 06:33 AM)Verstak Wrote: And final remark, related to ductility (I think). In erosion test the WC-10Co-4Cr AK-HVAF coatings performed better at 90 degree angle of attack as compared to 30 degree angle. Data from several sources already. Explain this without using term "ductility".

One can't have it all. But one can have more with HVAF carbides.

Regards,
Andrew Verstak
Kermetico Inc.

Thank you, Andrew

I am a big fan of your equipment, and I totally agree that it gives much more value both for a customer and a thermal spray shop.

BR
Vig
Reply
10-09-2016, 12:58 PM,
#8
RE: HVAF vs. HVOF WCCoCr
Hello Vig,

At the beginning of this topic I thought that this is an invitation to a technical discussion on HVAF and HVOF. After your negative rating for my opinion on the grounds: "Trying to deny the results of common evaluation techniques in favor of own viewpoint is not a good method of discussion", I see that it is only the advertising for Kermetico.

Discussions where only one opinion is accepted do not interest me.

BR
Vadim
Reply
10-09-2016, 07:42 PM,
#9
RE: HVAF vs. HVOF WCCoCr
(10-09-2016, 12:58 PM)Vadim Verlotski Wrote: Hello Vig,

At the beginning of this topic I thought that this is an invitation to a technical discussion on HVAF and HVOF. After your negative rating for my opinion on the grounds: "Trying to deny the results of common evaluation techniques in favor of own viewpoint is not a good method of discussion", I see that it is only the advertising for Kermetico.

Discussions where only one opinion is accepted do not interest me.

BR
Vadim

Dear Vadim

It IS an invitation for a technical discussion.

Besides HVOF, I have an experience with one type of HVAF equipment - Kermetico one, that is why I discuss it.

I am sorry that you got it personal.
I appreciate your contribution and would like to read more of your thoughts.

On the rest, I'll reply in a private message.

BR
Vig
Reply
05-07-2017, 12:48 PM,
#10
RE: HVAF vs. HVOF WCCoCr
(10-08-2016, 06:33 AM)Verstak Wrote:
(10-07-2016, 09:35 AM)Vadim Verlotski Wrote:
(10-06-2016, 07:40 PM)Vig Wrote: Hi, Vadim

Thank you for your thought.

There is one more explanation.
What makes sprayed WC-Co-Cr that brittle? W2C, which is present in HVOF coatings and absent in HVAF.
May this lack of W2C be a reason for high ductility?
Check this ITSC-2015 presentation, and you will find that HVAF modulus of elasticity is ... 1,5 higher than HVOF's!
Which leads to much better cavitation and erosion test results.

Could you imagine poor wear- or corrosion resistance of the coating with the micro-cuts you can see at the link I shared in the first post?
And believe me, they are not unique picks.
My last company used Kermetico equipment for 10+ years, so I haven't just heard it on the grapevine.

BR,
Vig

How do you manage to pump 7000 l / min of air through your burner. This is not taking into account propane.

Hi Vig,

In my opinion is the micro-indentation technique for determination of Young’s Modulus absolutely not applicable to the all of spraying layers. In this technique, modulus of elasticity is determined for individual grains in the material, but not for the entire layer, which has other phases, grain boundaries, cracks, pores, and other defects. In reality, no coating layers have Young’s Modulus greater than 300 GPa, otherwise they would not have retained on the steel substrate.
A layer of WC-Co-Cr has a very low thermal expansion coefficient (about 5x10-6K-1). The difference with the steel substrate is greater than 6x10-6K-1 and therefore the layer gets very high mechanical stresses during heating and cooling. If such a layer had the modulus of elasticity above 200 GPa, it would already have peeled off yet at 100°C temperature difference.
Since the real WC-Co-Cr layers can withstand more than 250°C temperature difference, it proves that the all must have Young’s Modulus only about 100-150 GPa. Thick layers which can withstand 350°C warm-up have a modulus of elasticity between 50 and 100 GPa, which means a weak cohesion.

One can not have everything at the same time: high modulus of elasticity (also means high strength, hardness and wear resistance) together with high ductility (also means bigness, great thickness, thermal shock resistance, high temperature application and other).

BR
Vadim

Vadim,
I respectfully disagree with majority of your statements.

1) The WC-10Co-4Cr material has no ductility

The WC-10Co-4Cr has 14 wt.% of Co-Cr metal alloy in it, or about 23 vol.%. Well, this alloy is pretty much ductile. Thus, the composite materials itself is ductile. Even if you saturated it with oxygen during HVOF spraying. And even when you dissolved tungsten and carbon in it. Still ductile. The HVAF coating is just more ductile, because of rate of oxidation and decarburization in the process is substantially lower. By the way, WC mono-carbide has some ductility. Contrary to W2C and majority of other carbides and borides.

2) Young modulus measurements technique is "false"

a) Microindentation is performed at loads 1 kg, 2 kg and even10 kg loads. At 1 kg load the indentation diagonal is about 40-50 micron. We are using WC-Co-Cr average particle size below 20 micron. And each particle deforms when forming the coating. Thus, with 1 kg indentation one is covering not individual grains, but several particles in the coating. Thus, 400 GPa modulus "belongs" to the coating.
b) The team from Indian Power Research Institute (Bangalore) was using "scratching technique" for modulus determination, getting 420-460 GPa for different AK-HVAF coatings and about 260 GPa for HVOF ones. Well, scratching through the whole coating thickness. And in different directions. So much for individual grains.

3) Stresses formation during coating deposition should destroy the coating with high modulus of elasticity

You are confusing cooling of the whole coating layer versus substrate AND stresses appearance and buildup during the coating formation which involves cooling of separate particles. And you completely ignore the impact of other particles, including those which did not deposit during spraying. Evidently, at DE 50% half of them strike the surface and bounce back.

Each particle cools down to the surface temperature individually, before next particle strikes it. The particle already formed the bonds to the substrate at higher temperature - somewhere in between the melting temperature of Co-Cr alloy and 1000 deg.C or so. Yes, CTE for the particle is lower than for the substrate, but it formed the bonds at above 1000 deg.C. The substrate was heated to "spray spot" surface temperature only - surely not above 400 deg. C. This minimizes the "shrinkage difference". But does not eliminates it completely.

The remaining "shrinkage difference" creates stresses between the particle and the substrate. Those stresses are substantially relived by plastic deformation and by micro-cracking, i.e. destruction of already formed bonds (yes, it's unavoidable). But the stress relieve requires some time. And here comes "handy" the impact of the next particle, which strikes but may or may not bond. This impact further affects stresses in the particle. Remaining "mismatch" results in formation of residual stresses between the sprayed particle and the substrate (let's call it "Type 1" stresses).

The Type 1 stresses accumulate in the layer, deposited per pass ("Type 2"). And Type 2 stresses from each layer accumulate in the coating, forming its final residual stresses field ("Type 3"). In fact, in all stages this is not just "sum of stresses". Type 1 is changing while the spray layer is formed; and Type 2 in previous layers is changing while applying new layers.
The point is that the structure of the coating is "frozen" at some elevated temperature. If this temperature is found correctly (job for a technology developer), the coating stays. If not - it cracks and/or delaminates.

In such scenario I do not see a direct correlation of cracking and Young modulus. Yes, stresses will be higher in the materials with higher Young modulus. But the cohesion strength will also be higher for such materials.

4) Stresses during heating should destroy the coating with high modulus

Again, the coating accumulate residual stresses (Type 3) at elevated temperature. When you start heating the coating, first thing you would see is a reduction of residual stresses. And only further heating would start building the stresses related to the thermal expansion mismatch between the coating and the substrate. And here comes at play the coating ductility. To the limited extend. Then cracking occurs.

Actually, during thermal cycling the carbide coatings usually crack. The issue is what kind of cracking it is. If cracks are isolated on "micro-level", the coating stays on the substrate and does its job. If micro-cracking results in macro-cracking - the coating fails. The same is true for cycling mechanical loads.

Again, it is more about coating thickness, coating structure and ductility rather then Young modulus.

5) Building of thick layers in HVAF as an evidence of "weakness"

The pinning effect of blasting particles during HVAF spraying is stronger than in HVOF (lower temperature of particles and higher velocity). The direct confirmation of this is that compressive residual stresses in HVAF are higher than in HVOF. Substantially. This is why a thicker layer per pass and a thicker total coating is possible to apply with HVAF. Not because it is "weak" material.

I do not see any logic in calling the same material weaker, when it has higher hardness, higher K1C and higher Young modulus.

Furthermore,there are publication and reports, directly comparing AK-HVAF WC-10C04Cr versus HVOF counterparts (JP5000, DJ2600, K2). The AK-HVAF improvements in testing:
a) Rubber Wheel test, Miller test, Pin-on-Disc test: 1.5-2.0 times
b) Silt erosion and dry erosion: 5+ times
c) Cavitation: 10+ times

I strongly agree with one statement: In the WC-10Co-4Cr coatings (like in majority of others), there are areas between sprayed particles without bonds - voids, micro-cracks, etc. It seems though, there are less of those in the HVAF carbide coatings .

And final remark, related to ductility (I think). In erosion test the WC-10Co-4Cr AK-HVAF coatings performed better at 90 degree angle of attack as compared to 30 degree angle. Data from several sources already. Explain this without using term "ductility".

One can't have it all. But one can have more with HVAF carbides.

Regards,
Andrew Verstak
Kermetico Inc.

Reply
05-08-2017, 09:29 AM,
#11
Thumbsup  RE: HVAF vs. HVOF WCCoCr
Hi, Nesher,
(05-07-2017, 12:48 PM)Nesher Wrote: How do you manage to pump 7000 l / min of air through your burner? This is not taking into account propane.
Thank you for this brilliant question.

Kermetico does not produce burners, so we do not need to pump anything through it :-)
When Kermetico designer creates an HVOF or HVAF thermal spray system, he thinks of proper heating and acceleration of the feedstock to make the best coating possible. You can read more here .

This results in the different guns for different tasks.
Kermetico has AK7, for spraying massive parts at 550 g/min - and this is a large gun, because you need a lot of energy for this throughput.
Universal AK5 which can spray into 200 mm internal diameter, needs much less air to spray at 250 g/min rate;
And AK-ID which deposits coatings into ID 80 mm and larger, needs less than 3000 l/min to spray at 80 g/min.

Not a high price for the freedom from an oxygen tank and a water cooler - we do not need them with Kermetico equiment to spray high velocity. And we rarely use cooling of the part - the jet is not that hot.

Best Regards,
Vig
Reply
05-18-2017, 12:08 PM,
#12
RE: HVAF vs. HVOF WCCoCr
Kermetico published an impressive webinar regarding Kermetico tungsten carbide coatings.
https://youtu.be/4QCKvOSo3W4
Last several minutes showing sprayed tungsten carbide cutting tool should get any skepticism regarding ductility of this coating out.
It is a masterpiece!
Regards,
Vig
Reply
05-22-2017, 10:37 AM, (This post was last modified: 05-22-2017, 11:07 AM by Nesher.)
#13
RE: HVAF vs. HVOF WCCoCr
(05-08-2017, 09:29 AM)Vig Wrote: Hi, Nesher,
(05-07-2017, 12:48 PM)Nesher Wrote: How do you manage to pump 7000 l / min of air through your burner? This is not taking into account propane.
Thank you for this brilliant question.

Kermetico does not produce burners, so we do not need to pump anything through it :-)
When Kermetico designer creates an HVOF or HVAF thermal spray system, he thinks of proper heating and acceleration of the feedstock to make the best coating possible. You can read more here .

This results in the different guns for different tasks.
Kermetico has AK7, for spraying massive parts at 550 g/min - and this is a large gun, because you need a lot of energy for this throughput.
Universal AK5 which can spray into 200 mm internal diameter, needs much less air to spray at 250 g/min rate;
And AK-ID which deposits coatings into ID 80 mm and larger, needs less than 3000 l/min to spray at 80 g/min.

Not a high price for the freedom from an oxygen tank and a water cooler - we do not need them with Kermetico equiment to spray high velocity. And we rarely use cooling of the part - the jet is not that hot.

Best Regards,
Vig

3000 l/min.......Smile))))) Price of such compressor?The price is comparable to the price of equipment. And if you take into account the cost of maintaining such a compressor ....
All technologies have the right to life. But you do not need to push them into a niche in which they are unprofitable.

(05-22-2017, 10:37 AM)Nesher Wrote:
(05-08-2017, 09:29 AM)Vig Wrote: Hi, Nesher,
(05-07-2017, 12:48 PM)Nesher Wrote: How do you manage to pump 7000 l / min of air through your burner? This is not taking into account propane.
Thank you for this brilliant question.

Kermetico does not produce burners, so we do not need to pump anything through it :-)
When Kermetico designer creates an HVOF or HVAF thermal spray system, he thinks of proper heating and acceleration of the feedstock to make the best coating possible. You can read more here .

This results in the different guns for different tasks.
Kermetico has AK7, for spraying massive parts at 550 g/min - and this is a large gun, because you need a lot of energy for this throughput.
Universal AK5 which can spray into 200 mm internal diameter, needs much less air to spray at 250 g/min rate;
And AK-ID which deposits coatings into ID 80 mm and larger, needs less than 3000 l/min to spray at 80 g/min.

Not a high price for the freedom from an oxygen tank and a water cooler - we do not need them with Kermetico equiment to spray high velocity. And we rarely use cooling of the part - the jet is not that hot.

Best Regards,


Vig

3000 l/min.......Smile))))) Price of such compressor?The price is comparable to the price of equipment. And if you take into account the cost of maintaining such a compressor ....
All technologies have the right to life. But you do not need to push them into a niche in which they are unprofitable.


"Please do not trust a person telling you that HVOF technology has an advantage over HVAF. He would either be unaware of the last five years of HVAF development or just trying to keep his competitive advantage, whatever it is.
Kermetico HVAF technology is MUCH better than HVOF in any aspect, including quality, cost, reliability and safety."
Your statements have no physical basis. You just kill us with such conclusions. Smile))



(05-22-2017, 10:37 AM)Nesher Wrote:
(05-08-2017, 09:29 AM)Vig Wrote: Hi, Nesher,
(05-07-2017, 12:48 PM)Nesher Wrote: How do you manage to pump 7000 l / min of air through your burner? This is not taking into account propane.
Thank you for this brilliant question.

Kermetico does not produce burners, so we do not need to pump anything through it :-)
When Kermetico designer creates an HVOF or HVAF thermal spray system, he thinks of proper heating and acceleration of the feedstock to make the best coating possible. You can read more here .

This results in the different guns for different tasks.
Kermetico has AK7, for spraying massive parts at 550 g/min - and this is a large gun, because you need a lot of energy for this throughput.
Universal AK5 which can spray into 200 mm internal diameter, needs much less air to spray at 250 g/min rate;
And AK-ID which deposits coatings into ID 80 mm and larger, needs less than 3000 l/min to spray at 80 g/min.

Not a high price for the freedom from an oxygen tank and a water cooler - we do not need them with Kermetico equiment to spray high velocity. And we rarely use cooling of the part - the jet is not that hot.

Best Regards,
Vig

3000 l/min.......Smile))))) Price of such compressor?The price is comparable to the price of equipment. And if you take into account the cost of maintaining such a compressor ....
All technologies have the right to life. But you do not need to push them into a niche in which they are unprofitable.

(05-22-2017, 10:37 AM)Nesher Wrote:
(05-08-2017, 09:29 AM)Vig Wrote: Hi, Nesher,
(05-07-2017, 12:48 PM)Nesher Wrote: How do you manage to pump 7000 l / min of air through your burner? This is not taking into account propane.
Thank you for this brilliant question.

Kermetico does not produce burners, so we do not need to pump anything through it :-)
When Kermetico designer creates an HVOF or HVAF thermal spray system, he thinks of proper heating and acceleration of the feedstock to make the best coating possible. You can read more here .

This results in the different guns for different tasks.
Kermetico has AK7, for spraying massive parts at 550 g/min - and this is a large gun, because you need a lot of energy for this throughput.
Universal AK5 which can spray into 200 mm internal diameter, needs much less air to spray at 250 g/min rate;
And AK-ID which deposits coatings into ID 80 mm and larger, needs less than 3000 l/min to spray at 80 g/min.

Not a high price for the freedom from an oxygen tank and a water cooler - we do not need them with Kermetico equiment to spray high velocity. And we rarely use cooling of the part - the jet is not that hot.

Best Regards,


Vig

3000 l/min.......Smile))))) Price of such compressor?The price is comparable to the price of equipment. And if you take into account the cost of maintaining such a compressor ....
All technologies have the right to life. But you do not need to push them into a niche in which they are unprofitable.


"Please do not trust a person telling you that HVOF technology has an advantage over HVAF. He would either be unaware of the last five years of HVAF development or just trying to keep his competitive advantage, whatever it is.
Kermetico HVAF technology is MUCH better than HVOF in any aspect, including quality, cost, reliability and safety."
Your statements have no physical basis. You just kill us with such conclusions. Smile))
It's strange that you do not know this. The name of the burner is used so that there would be no problems for the equipment at the customs. When the gun is written at the customs, problems arise.

(10-06-2016, 03:52 PM)Vig Wrote: Kermetico Inc claims here that its AK-series HVAF equipment reached WCCoCr coating quality of 1450-1700 HV300 hardness, less than 0,3% porosity, no cracking (ductile). Kermetico even posted a YouTube video showing the HVAF-sprayed carbide tool for turning.
VTT, Finland as well as other researchers support these claims with their academic papers.
That coating quality definitely means huge new market possibilities for the WCCoCr thermal spray applications, but somehow it is not widely accepted by the industry yet.
What is it? Inertia or underestimation?

Please, share your thoughts.
Vig

This is a real assessment of the process by practice.The process has the right to life, but .. but .. but

Reply
05-22-2017, 02:21 PM,
#14
RE: HVAF vs. HVOF WCCoCr
Hi, Nesher

A good compressor does not need a lot to service it. Wise sprayers are not rich enough to buy crap. They choose the best equipment and a good compressor and save 50% of HVOF cost on each part sprayed.

One could continue to dream of a "good inexpensive HVOF coating" or join the team of advanced users of HVAF. It's a matter of choice.
Your customers will buy better coatings with the best prices from the one who will make it. Wish it would be you.

Best regards,
Vig
Reply
05-22-2017, 05:54 PM,
#15
RE: HVAF vs. HVOF WCCoCr
Dear Vitaly,
You really mean that your aggressive advertising policy attracts the new customers for Kermetico? One should not be too loud to be heard.
Nobody says that the modern HVAF technique of Andrei Verstak and Slava Baranovski is not good. This technique is very good, but that does not mean that HVOF technology has no more authority. For example, Boris' Termika-3 is also very good for certain applications. You can not compare apples with pears.
It is not just about the gigantic productivity of AK7 or AK6, which is superfluous for coating small parts. For many special cases, the small system with a hot torch is simply more practical.
Although we also produce high-performance HVOF systems that produce carbide layers with do not worse than Ultra HVAF layers from Kermetico, I do not say that all other systems are bad. HVOF also has certain advantages that you do not want to accept.
Regards
Vadim
Reply
05-23-2017, 07:24 AM,
#16
RE: HVAF vs. HVOF WCCoCr
(05-22-2017, 02:21 PM)Vig Wrote: Hi, Nesher

A good compressor does not need a lot to service it. Wise sprayers are not rich enough to buy crap. They choose the best equipment and a good compressor and save 50% of HVOF cost on each part sprayed.

One could continue to dream of a "good inexpensive HVOF coating" or join the team of advanced users of HVAF. It's a matter of choice.
Your customers will buy better coatings with the best prices from the one who will make it. Wish it would be you.

Best regards,
Vig

Dear Sir
Practice and time everything settles into place. I do not see the mass use of HVAF technology. I repeat that it has the right to life, but in a very narrow range of applications. I have already spoken about the reasons.
Negative aspect is a lot.Especially the 45% using of powder.
There are no technologies that are better than all. And you are trying to prove that which is not.

Reply
05-23-2017, 02:23 PM, (This post was last modified: 05-23-2017, 02:53 PM by Vig.)
#17
RE: HVAF vs. HVOF WCCoCr
(05-22-2017, 05:54 PM)Vadim Verlotski Wrote: Dear Vitaly,
This technique is very good, but that does not mean that HVOF technology has no more authority. For example, Boris' Termika-3 is also very good for certain applications. You can not compare apples with pears.
It is not just about the gigantic productivity of AK7 or AK6, which is superfluous for coating small parts. For many special cases, the small system with a hot torch is simply more practical.
Although we also produce high-performance HVOF systems that produce carbide layers with do not worse than Ultra HVAF layers from Kermetico, I do not say that all other systems are bad. HVOF also has certain advantages that you do not want to accept.
Regards
Vadim

Thank you, Vadim
I totally agree, there are some niches, where low productivity and low-quality guns will be in need, but mainstream manufacturing needs higher quality coatings and higher productivity guns.
Well, spraying WCCoCr 550 g/min with AK7 or 450 g/min with AK6 could be too much for many applications, agree again. There is AK5, with spray rate of 250 g/min - 3 times productivity of old-style HVOF guns.
What I like in Kermetico - Andrew Verstak listens to the market and makes systems that the market needs.
Way to go.
King regards,
Vig

(05-23-2017, 07:24 AM)Nesher Wrote: Dear Sir
Practice and time everything settles into place. I do not see the mass use of HVAF technology. I repeat that it has the right to life, but in a very narrow range of applications. I have already spoken about the reasons.
Negative aspect is a lot.Especially the 45% using of powder.
There are no technologies that are better than all. And you are trying to prove that which is not.

Dear Nesher
HVOF systems were rare 20 years ago. A car has not been used massively 100 years ago.
More energy efficient technology kills less effective one. We see it every day.
One can imagine many negative effects (as it was with automobiles many years ago) - people will choose the most convenient instrument.
I do not know why have you stuck with 45% DE.
DE is a side effect of coating quality you need.
With Kermetico AK7 one can spray a coating with the hardness of
1050-1250 HV0.3 with 65% DE
1250-1350 HV0.3 with 48-58% DE
1350-1500 HV0.3 with 38-42% DE

It is the matter of a choice, not something mysterious. Worth trying.

King regards,
Vig
Reply
05-24-2017, 10:31 AM,
#18
RE: HVAF vs. HVOF WCCoCr
(05-23-2017, 02:23 PM)Vig Wrote:
(05-22-2017, 05:54 PM)Vadim Verlotski Wrote: Dear Vitaly,
This technique is very good, but that does not mean that HVOF technology has no more authority. For example, Boris' Termika-3 is also very good for certain applications. You can not compare apples with pears.
It is not just about the gigantic productivity of AK7 or AK6, which is superfluous for coating small parts. For many special cases, the small system with a hot torch is simply more practical.
Although we also produce high-performance HVOF systems that produce carbide layers with do not worse than Ultra HVAF layers from Kermetico, I do not say that all other systems are bad. HVOF also has certain advantages that you do not want to accept.
Regards
Vadim

Thank you, Vadim
I totally agree, there are some niches, where low productivity and low-quality guns will be in need, but mainstream manufacturing needs higher quality coatings and higher productivity guns.
Well, spraying WCCoCr 550 g/min with AK7 or 450 g/min with AK6 could be too much for many applications, agree again. There is AK5, with spray rate of 250 g/min - 3 times productivity of old-style HVOF guns.
What I like in Kermetico - Andrew Verstak listens to the market and makes systems that the market needs.
Way to go.
King regards,
Vig

(05-23-2017, 07:24 AM)Nesher Wrote: Dear Sir
Practice and time everything settles into place. I do not see the mass use of HVAF technology. I repeat that it has the right to life, but in a very narrow range of applications. I have already spoken about the reasons.
Negative aspect is a lot.Especially the 45% using of powder.
There are no technologies that are better than all. And you are trying to prove that which is not.

Dear Nesher
HVOF systems were rare 20 years ago. A car has not been used massively 100 years ago.
More energy efficient technology kills less effective one. We see it every day.
One can imagine many negative effects (as it was with automobiles many years ago) - people will choose the most convenient instrument.
I do not know why have you stuck with 45% DE.
DE is a side effect of coating quality you need.
With Kermetico AK7 one can spray a coating with the hardness of
1050-1250 HV0.3 with 65% DE
1250-1350 HV0.3 with 48-58% DE
1350-1500 HV0.3 with 38-42% DE

It is the matter of a choice, not something mysterious. Worth trying.

King regards,
Vig

Dear Sir
Mr.Vadim Verlotski told you all very professionally. I also wrote to you in the email. Life will show .
Sincerely yours
Dr.Boris A.Eizner (Nesher)
A.Termika Ltd

Reply
05-24-2017, 12:15 PM,
#19
RE: HVAF vs. HVOF WCCoCr
(05-24-2017, 10:31 AM)Nesher Wrote:
(05-23-2017, 02:23 PM)Vig Wrote: [quote='Vadim Verlotski' pid='10759' dateline='1495472070']
Dear Vitaly,
This technique is very good, but that does not mean that HVOF technology has no more authority. For example, Boris' Termika-3 is also very good for certain applications. You can not compare apples with pears.
It is not just about the gigantic productivity of AK7 or AK6, which is superfluous for coating small parts. For many special cases, the small system with a hot torch is simply more practical.
Although we also produce high-performance HVOF systems that produce carbide layers with do not worse than Ultra HVAF layers from Kermetico, I do not say that all other systems are bad. HVOF also has certain advantages that you do not want to accept.
Regards
Vadim

Thank you, Vadim
I totally agree, there are some niches, where low productivity and low-quality guns will be in need, but mainstream manufacturing needs higher quality coatings and higher productivity guns.
Well, spraying WCCoCr 550 g/min with AK7 or 450 g/min with AK6 could be too much for many applications, agree again. There is AK5, with spray rate of 250 g/min - 3 times productivity of old-style HVOF guns.
What I like in Kermetico - Andrew Verstak listens to the market and makes systems that the market needs.
Way to go.
King regards,
Vig

(05-23-2017, 07:24 AM)Nesher Wrote: Dear Sir
Practice and time everything settles into place. I do not see the mass use of HVAF technology. I repeat that it has the right to life, but in a very narrow range of applications. I have already spoken about the reasons.
Negative aspect is a lot.Especially the 45% using of powder.
There are no technologies that are better than all. And you are trying to prove that which is not.

Dear Nesher
HVOF systems were rare 20 years ago. A car has not been used massively 100 years ago.
More energy efficient technology kills less effective one. We see it every day.
One can imagine many negative effects (as it was with automobiles many years ago) - people will choose the most convenient instrument.
I do not know why have you stuck with 45% DE.
DE is a side effect of coating quality you need.
With Kermetico AK7 one can spray a coating with the hardness of
1050-1250 HV0.3 with 65% DE
1250-1350 HV0.3 with 48-58% DE
1350-1500 HV0.3 with 38-42% DE

It is the matter of a choice, not something mysterious. Worth trying.

King regards,
Vig

Dear Sir
Mr.Vadim Verlotski told you all very professionally. I also wrote to you in the email. Life will show .
Sincerely yours
Dr.Boris A.Eizner (Nesher)
A.Termika Ltd

And a little more:

I totally agree, there are some niches, where low productivity and low-quality guns will be in need, but mainstream manufacturing needs higher quality coatings and higher productivity guns.
-There is no connection between the performance of equipment with the quality of the coating.Installations with low capacity give excellent quality coatings. Sorry,but you do not understand what you write.

DE is a side effect of coating quality you need.
-This is not a serious statement.When you throw more than half of the expensive powder into shit, this indicates the imperfection of equipment and technology.



Reply
06-05-2017, 12:05 PM,
#20
Star  RE: HVAF vs. HVOF WCCoCr
One more niche has been filled with HVAF recently:
abrasion resistant coatings for 200-400 mm internal diameters.

Compact AK5-ID sprays 250 g/min WCCoCr into 200 mm IDs and larger.Exclamation
The depth is not limited.

Best Regards
Vig
Reply




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