I have a question, Does any one have experience or know something about the interaction of a thermal spray coating 88 WC-12Co HVOF with Hydrogen (H2) and natural gas at approximately 150 celcius?? Is there a posibility of a chemical reaction??
I read something of mechanical seals and the WC-Ni materials have good performance, what do you think??
I woundering if some drawings of thermal spray equipment are avaible into Internet. I know that most of HVOF and plasma guns are very old (Jetkote/JP5000/3/7/9/MB/F-4/SG-100) and spare parts were copied by many companies. They are not protected by patents. Can anybody tell me where I can find some drawings with dimensions ?
I have a craking problem in the 88-12 HVOF tungsten carbide coating on a wire drawing capstan, Actually we make the coatings with the HVOF thermal spray system using hidrogen- oxygen (gases).
We usually use TWAS 1/16 in carbon steel class ER70s-6 AWS 5.18 like a filling coating, this beacause the wire drawing capstans that we remanufacturing have several wear, approximately 0.090 in (0.180 in diameter) I think its a lot a probably this could be the reason that cause the cracking problem but Im not sure because this is not a problem often arising in the wire drawing, in addition we apply filling coating in the 90% of the capstans.
Do you have experience with this kind of problems??
i've a customer who asked me to apply coating on a 360 mm diameter tube made of Fe430 (s275) for dimensional restoration, weight of the component is about 250-300 kg.
I've tried several times to apply coating by oxy-acetylene flame with my Uni Spray Jet from UTP (similar to castodyn DS 8000) but coating fails to adhere to the substrate and it comes off when cutting it on the lathe. Coating is about 0.5-0.6mm once turned on the lathe (0.8-0.9 mm as sprayed).
Procedure that i followed is:
- Acetone cleaning
- Surface preparation by turning it on the lathe removing few cents of material JUST BEFORE COATING.
- NO grit blasting as job is being done on customer site and i don't have a vacuum blasting equipment to salvage the material being used and not mess everything around. Piece won't fit my gritblasting cabinet as well.
-NO preheating as the surface being coated, if directly heated with the flame, tends to become yellowish (oxidize) pretty quickly but the piece, due to it's big mass, doesn't warm up at all (after 10 minutes of coating it's around 100°C)
- Coating with NiAl 95/5 (45-90um) with neutral flame.
I'm going to give it a last try grit blasting the surface prior to coating as it should be done but i knew, not from experience, that NiAl should be able to bond also to "shiny metal". Isn't that true?
Do you have any suggestione/advice to give me?
Grit blasting should be the final solution but i'd like to have your opinion as well perhaps i'm missing something......
Thanks a lot and sorry for the long post!
have a nice day!
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?
i need help in selecting the correct coating material for our application.
We want to apply a ceramic coating on Vehicle Exhausts by Plasma Spraying.
The actual mechanic attributes of the coating are not important, as we do the coating only for aesthetics.
Important points are only:
- The coating needs to be dark grey-black. The darker the better
- The coating needs to be heat resistant. Our exhausts are usually at around 400 degrees Celcius, but can reach up to 800 degrees for a short time.
- The coating needs to be ready "as sprayed". Due to the shape and tolerances in shape/size of our exhausts, it's not feasible to grind/polish the coating after it has been applied also application of a sealer is not an option.
The manufacturer of our Plasma Spray equipment suggested us a ceramic 60% Aluminium Oxide 40% Titanium Dioxide
We tested it and we're very happy with the surface quality/roughness as well as with it's heat resistance.
The only problem is that this material is rather light gray/blueish, we can not accept the color.
I would greatly appreciate suggestions for other possible coating materials which we could try.