sealbond-N vs Nickel eletrolesess

[aracioppi]

I´m trying to find out the relationship between sealbond-N coating and Nickel electrolesess (if there is a relationship)
Otherwise wich is better? in wich cases?

Thanks a lot

 

[kenvlach]

Two very different processes.
SealBond N = nitrocarburise + seal. Nitrocarburizing is a case hardening process in which C and N atoms enter into the steel. There is little or no increase in dimension. I expect it has a dark gray appearance. It doesn’t have any corrosion resistance, so some proprietary type of sealant is added afterwards. Some corrosion test results (salt spray per ASTM B117) resulted in 55% of panel covered with red rust.

http://www.cdcralternatives.ctc.com/getdataaction.cfm?TechID=129

Test exposure hours were not stated, but I found results for SealBond E (also nitrocarburise + seal): ASTM B 117 - 10% of panel covered with black oxide after 150 hrs, 3% of panel covered with red rust after 198 hrs.

http://www.cdcralternatives.ctc.com/getdataaction.cfm?TechID=128

Electroless nickel is a plating process which can be used on just about any metal (or even plastics, with proper pretreatment). There are various types of EN, but the common ones are low-, mid- and high-phosphorous alloys. Corrosion resistance increases (while brightness decreases) with increase in P content. Typical protection vs. salt spray might be 25, 100 and 1000 hours, respectively, for 0.001” thickness. An intro to the different types:

http://www.macindustrialproducts.com/entypes.html

Some properties such as hardness, both as plated and after heat treatment, are given at

http://www.macindustrialproducts.com/properties.html

EN adds thickness. Coatings as thin as 2.5 micrometers (0.1 mil) are commonly applied for electronic components, while those as thick as 75 to 125 micrometers (3 to 5 mils) are typical for corrosive environments. Coatings thicker than 250 micrometers (10 mils) are used for salvage and repair of worn or mismachined parts.

http://www.macindustrialproducts.com/engineering.html

For a little more comparison, nitrocarburizing is usually used where where resistance is needed, such as gears. EN is not as hard, but adds resistance to wear, galling and corrosion as well as giving a bright finish.
Hope this helps,
Ken

 

[aracioppi]

kenvlach:
Ok, I understand what you mean.
A Client is asking me to provide a valve actuator wich shaft pinion coated with Nickel electroless.
I found an actuator with it shaft pinion coated with sealbond-N, so I don´t know of chemistry I decided to ask.
So, in the case I mention, both processes wouldn´t act the same??
Thanks again

 

[kenvlach]

This sounds like a lubricated application inside a valve cover, so high corrosion resistance isn't necessary. For EN, a low-phosphorous type heat-treated for maximum hardness would give the best results. For the Sealbond-N, ask the vendor whether the sealant is resistant to motor oil (or whatever lubricant is used). If not, just carbonitriding alone should give a very wear-resistant surface.

 

[aracioppi]

Ok, I´ll ask wich of them they prefer

Thanks a lot

 

[aracioppi]

one more question
is TFE the same as Chevron type teflon?

 

[kenvlach]

TFE is probably shorthand for PTFE, polytetrafluoroethylene, but you had better verify. PTFE is the generic chemical name for DuPont’s Teflon®. Is this the ‘seal’ in the Sealbond-N? Teflon® is very good at reducing friction, but doesn’t handle high loads, especially at elevated temperature.

To increase the lubricity of EN (which is already better than most metals), you might want to consider an EN coating containing co-deposited PTFE particles.

Any chance of doing comparison testing? Too many variables such as temperature and loading to make a determination from afar.

 

[aracioppi]

Ok, Kenvlach, but I´m asking for a different thing.
They are asking me for a valve with chevron type stem packing, and I found a valve with TFE packing, so I wanted to know if TFE was related with chevron TFE
Thanks