Plasma Spray of Chromium
Plasma Spray of Chromium
(OP)
I have a potential client that plasma sprays print rolls with a chromium oxide feedstock for wear resistance using hydrogen as the reductant? (the fuel as well?) in the presence of an inert argon atmosphere. They complain of low deposition yield rates of the chromium on the print rools with a significant amount going up the vent stack and not reclaimable (sounds like a pollution control problem as well...).
Does anyone know where I can read up on the factors that influence deposition yield rates on the print rolls? I was going to suggest that the target roll be induction heated to bring it up to a temperature suitable for better deposition rates. Does this make sense or is there a better, more effective way?
Does anyone know where I can read up on the factors that influence deposition yield rates on the print rolls? I was going to suggest that the target roll be induction heated to bring it up to a temperature suitable for better deposition rates. Does this make sense or is there a better, more effective way?
RE: Plasma Spray of Chromium
http://www.asminternational.org/MSTemplate.cfm?Section=Email_Discussion_List&Site=Thermal_Spray_Society&Template=/ContentManagement/HTMLDisplay.cfm&ContentID=3074
You'll get a lot of feedback.
Generally, deposition is a function of deposition method and heat.
RE: Plasma Spray of Chromium
The argon is used for its easy ionizability; the hydrogen increases the heat capacity of the gas-plasma. Your low deposition and losses suggest that the plasma core temperature is too low (cf. 30000oC according to Praxair).
General process info is given in 'Thermal Spray Coatings,' pp. 497-509 in ASM Handbook, vol. 5 Surface Engineering.
An overview of 'Plasma and Chromium Oxide Coated Rolls' is given by Praxair: http://praxairsurfacetechnologies.com/pst%5Fprinting%5Fweb/plas%5Fchrom%5Fcoated.html
and a bit of detailed information on 'Plasma Torch & Chromium Oxide Coatings Technology' can be downloaded at
http://praxairsurfacetechnologies.com/pst%5Fprinting%5Fweb/PDFs/HF-06.pdf
[It's not really that detailed; suggests contacting Praxair Surface Technologies technical field sales representatives. Phone nos. given for US, UK, Switz., Germany, Italy, Japan & Japan.]
RE: Plasma Spray of Chromium
MetalMike
Metal Mike
Technology Director - Applied Technology Group
RE: Plasma Spray of Chromium
RE: Plasma Spray of Chromium
RE: Plasma Spray of Chromium
We allow nickel and chrome plated surfaces to be reconditioned with a thin layer of Tungsten Carbide powder M5803 (METCO) spray onto the shaft surface. This process produces a corrosion resistant wear surface with a surface hardness ranging from 68-72 Rc. The HVOF process can obtain higher density coatings and finer surface finishes compared to other coating processes such as chromium plating. Other advantages include, a more simplified application process, no part size restrictions and no hazardous waste products.
info see:
http://www.hcat.org/documents/AESF%20Plating%20Forum%20Mar1998.pdf
and
http://www.dresser-rand.com/services/coatings/eec-tc.htm
RE: Plasma Spray of Chromium
* see honeycomb cell structure of controlled ink capacity at http://www.harperimage.com/LaserKote/laserkote2.htm
**Praxair coats rolls after engraving with epoxy sealer, which certainly affects some of these properties.
RE: Plasma Spray of Chromium
Scott.Lacourse@sulzer.com
was very useful. In any event, the TSS board is for such questions.