SS 321 wire for Metallisation
10-20-2008, 09:32 AM,
#1
SS 321 wire for Metallisation
We have a requirement where in the customer requires a deposit of SS321 on Carbon Steel Plate. We would like to know the equivalent TAFA wires for SS321.

The application is for Corrosion protection. Can we deposit TAFA 60 T which primarily is SS420. Will it work?
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10-20-2008, 11:18 AM,
#2
RE: SS 321 wire for Metallisation
Hi Ehasan,
As far as I knew SS420 only chromium content, without nickel, where SS 321 has some amount of nickel, all the first digit with 3, so depend on what kind of corrosion will occurs ? still needed Ni alloy to protect ? cos' corrosion itself was many kind of corrosion, it is wet corrosion or dry corrosion ? what liquid for wet or how high working temperature for dry one ? etc.
That's all, suppose this forum has Corrosion Engineer that can explain more detailed ?
Thanks & Regards,
Iwan Sedaryawan - Website : https://www.ciptaagung.com
Happy0193
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10-22-2008, 06:12 PM,
#3
RE: SS 321 wire for Metallisation
Hi Ehasan,

You need to be careful when a customer specifies a material for a coating. They may have good knowledge of properties of bulk wrought material, but that is not the same as the coating. Better approach would be to find out the actually properties that are required of the coating, and let that be the basis for choice amongst the readily available thermal spray wires.

AISI 321 is an 18Cr/10Ni austenitic stainless, the closest Tafa wires are 80T (AISI 304 series 18Cr/8Ni) or 85T (AISI 316 17Cr/12Ni). For corrosion applications tafa 60T (AISI 420 13Cr steel) will probably not be good enough as iwan-sedaryawan says.

You need to remember that the corrosion resistance say of AISI 316 stainless steel will probably be somewhat better than a coating produced from 316. So sometimes you need to consider selecting a higher Cr, Ni alloy content coating material to compensate.

Tafa wires like 77T (Hastelloy C-276 type), 78T (inconel 718 type) and inconel 625 (not sure of Tafa name) may be worth consideration depending on corrosive environment.

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10-23-2008, 04:01 AM,
#4
RE: SS 321 wire for Metallisation
[quote='Gordon' pid='2639' dateline='1224695546']
Hi Ehasan,

You need to be careful when a customer specifies a material for a coating. They may have good knowledge of properties of bulk wrought material, but that is not the same as the coating. Better approach would be to find out the actually properties that are required of the coating, and let that be the basis for choice amongst the readily available thermal spray wires.

AISI 321 is an 18Cr/10Ni austenitic stainless, the closest Tafa wires are 80T (AISI 304 series 18Cr/8Ni) or 85T (AISI 316 17Cr/12Ni). For corrosion applications tafa 60T (AISI 420 13Cr steel) will probably not be good enough as iwan-sedaryawan says.

You need to remember that the corrosion resistance say of AISI 316 stainless steel will probably be somewhat better than a coating produced from 316. So sometimes you need to consider selecting a higher Cr, Ni alloy content coating material to compensate.

Tafa wires like 77T (Hastelloy C-276 type), 78T (inconel 718 type) and inconel 625 (not sure of Tafa name) may be worth consideration depending on corrosive environment.



Dear Gordon,

We have used 80T & 85T previously as a cladding material on C.S. But the same failed. The entire cladding had a rust like formation within a month. The entire job we had to re-clad with thin sheet cladding.

We have not tried with Hastelloy or Inconel as you suggest. We have asked TAFA ppl for suggestion and they never cam back for the reason of failure.

Could you please throw some light on the reason for the failure.

Thanks
Ehasan
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10-23-2008, 05:25 PM,
#5
RE: SS 321 wire for Metallisation
Hi Ehasan,

It may be difficult to pin point reason for failure, even if I had all the information, history and samples to hand. With the information available here I can only guess at a few possible scenarios:

* Environment too corrosive for selected coatings (try inconel 625, hastelloy c or other)

* Lack of sealing or sealer poorly applied or sealer not up to environment (even if coating is fully resistant corrosion, it needs to be a 100% barrier)

* Poorly applied coating, poor coating quality, coating cracks etc.

* Customer using cleaning/washing treatments that you may not be aware of; bleach, acid, alkali washes etc.
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10-24-2008, 04:55 AM,
#6
RE: SS 321 wire for Metallisation
(10-23-2008, 05:25 PM)Gordon Wrote: Hi Ehasan,

It may be difficult to pin point reason for failure, even if I had all the information, history and samples to hand. With the information available here I can only guess at a few possible scenarios:

* Environment too corrosive for selected coatings (try inconel 625, hastelloy c or other)

* Lack of sealing or sealer poorly applied or sealer not up to environment (even if coating is fully resistant corrosion, it needs to be a 100% barrier)

* Poorly applied coating, poor coating quality, coating cracks etc.

* Customer using cleaning/washing treatments that you may not be aware of; bleach, acid, alkali washes etc.

What normally should be the sealant thickness in such application. Can you tell about any good quality Sealant for Alkali (light) & Acid (light) along with make.

Personally I feel that it was the failure due to Quality/thickness of sealant.

Thanks
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10-24-2008, 10:30 AM,
#7
RE: SS 321 wire for Metallisation
Sealing of coatings should not normally be specified with a thickness. It actually detracts from the purpose of the sealing coat which is to penetrate the porosity in the coating. Therefore, you should apply the sealant until it has filled the pores rather than created a thick coating. At times, the sealant thickness is specified as say 25 microns, just to 'prove' that there has been penetration.
Stuart Milton
Metallisation Ltd
https://www.metallisation.com
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10-24-2008, 08:06 PM,
#8
RE: SS 321 wire for Metallisation
Hi Ehasan,

Stuart is right, sealers are primarily for penetration and sealing Happy0193 and not for producing a paint film, although some systems do serve as both sealer and paint system mainly in anti-corrosion coatings.

Choice of sealer is a difficult one, and often an aspect of thermal spray coatings that is poorly addressed. We have a vast range of coating materials products to choose from, but very few sealer products. The sealer can be a critical part of some coating systems. We spend much effort selecting the best thermal spray coating material for the job, but all to often neglect that the same care is needed in selecting a sealer, an equally important part of some coating systems.

Quote:Can you tell about any good quality Sealant for Alkali (light) & Acid (light) along with make.
I can't really advise on a particular sealer for your application, probably many of the commercially available sealers would claim to be suitable for use as you describe. Selection is a complex issue. Ask your supplier about their range of sealers and their recommendation for your particular application. Then question and research what they recommend to see if there is a better option. Happy0193

If you are machining/grinding coating, it is wise to seal a second time afterwards, as coating removal may expose new pathways through coating. Make sure coating is DRY and clean (avoids sealing in moisture) before sealing. You may say, why seal before machining then? Well this is important to stop ingress of contaminants into coating (water, cutting fluids, grit etc.) and some sealers can improve machining process. Also, ensure sealer has fully cured before being put into service, particularly important with regard to the linseed oil based sealers which can take weeks to cure unaided (like Metcoseal AG). Often neglected nowadays, if service temperature is low, no hydrocarbon sovents, just aqueous water based environment, the old melt on wax sealers can be very effective.
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06-06-2018, 09:43 PM,
#9
RE: SS 321 wire for Metallisation
I have a query to the HVOF application of Chromium Carbide with subsequent densification, thermochemically diffuses a sealant throughout the plating/coating, fi lling the porosity with corrosion resistant, super hard ceramic particles, need to resist temperatures up to 760°C
Does anybody knows what is it, and what is the sealant applyed to obtain this result.
I need to know too where I can find this sealant via import and if the supplier can deliver here to Brazil.
Tks
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06-07-2018, 07:41 AM,
#10
RE: SS 321 wire for Metallisation
(06-06-2018, 09:43 PM)Wagner Martines Wrote: I have a query to the HVOF application of Chromium Carbide with subsequent densification, thermochemically diffuses a sealant throughout the plating/coating, fi lling the porosity with corrosion resistant, super hard ceramic particles, need to resist temperatures up to 760°C
Does anybody knows what is it, and what is the sealant applyed to obtain this result.
I need to know too where I can find this sealant via import and if the supplier can deliver here to Brazil.
Tks
No polymer can withstand temperatures over 350°C, so there is no sealants for high temperature applications. For use at 760°C you need an oxidation-resistant coating that is gas-tight without sealants.
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06-07-2018, 02:14 PM, (This post was last modified: 06-07-2018, 02:15 PM by Wagner Martines.)
#11
RE: SS 321 wire for Metallisation
(06-07-2018, 07:41 AM)Vadim Verlotski Wrote:
(06-06-2018, 09:43 PM)Wagner Martines Wrote: I have a query to the HVOF application of Chromium Carbide with subsequent densification, thermochemically diffuses a sealant throughout the plating/coating, fi lling the porosity with corrosion resistant, super hard ceramic particles, need to resist temperatures up to 760°C
Does anybody knows what is it, and what is the sealant applyed to obtain this result.
I need to know too where I can find this sealant via import and if the supplier can deliver here to Brazil.
Tks
No polymer can withstand temperatures over 350°C, so there is no sealants for high temperature applications. For use at 760°C you need an oxidation-resistant coating that is gas-tight without sealants.


(06-07-2018, 07:41 AM)Vadim Verlotski Wrote:
(06-06-2018, 09:43 PM)Wagner Martines Wrote: I have a query to the HVOF application of Chromium Carbide with subsequent densification, thermochemically diffuses a sealant throughout the plating/coating, fi lling the porosity with corrosion resistant, super hard ceramic particles, need to resist temperatures up to 760°C
Does anybody knows what is it, and what is the sealant applyed to obtain this result.
I need to know too where I can find this sealant via import and if the supplier can deliver here to Brazil.
Tks
No polymer can withstand temperatures over 350°C, so there is no sealants for high temperature applications. For use at 760°C you need an oxidation-resistant coating that is gas-tight without sealants.
Look for this => https://metallisation.com/app/uploads/20...ealht1.pdf

Dear Vadin, look for this => https://metallisation.com/app/uploads/20...ealht1.pdf
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