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-----Hard anodize gears for cryogenics
Quickstart:
In the anodizing of aluminum the components are immersed into a tank of acidic solution and connected to the anodic (+) positive pole of a power supply. The current separates some of the water in the solution into positively charged hydrogen and negatively charged oxygen. The oxygen is attracted to the positively charged components and converts the skin of the aluminum to aluminum oxides.
Readers new to anodizing of aluminum may wish to view our "Intro to Aluminum Anodizing".
The coefficient of thermal expansion of anodized coatings differs greatly from that of aluminum, so some readers question the use of anodized aluminum for cryogenic temperatures.
Q. I have small 7075 alum. chassis and tiny electric motor components that need to be cryogenically treated/annealed.
Anyone know anything about these procedures?
(I think) I want my own tanks--and be set up for this service. Thanxks.
Judd Kincaid- Los Banos, California
2000
A. Hi Judd. There are companies who offer cryogenic treatment service. I'm sure they would be happy to explain the service in general terms so that you can decide whether you want to use jobshop services for this vs. install the equipment to do it yourself. Good luck.
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Q. Hello, My name is Rick, I work as a mechanical designer/machinist in a University Physics Department. I am making 15" diameter aluminum gears for use in a cryogenic environment (vacuum and 4 degrees Kelvin). I would like some coating options to improve the strength and wear of the teeth. Something that will not out-gas or flake off in use.
Teeth are 24 DP, 360 teeth,1/8" thickness. This will be a low torque, low rpm application.
Your assistance in this matter will be much appreciated. Thank you.
Research University Designer - Cleveland, Ohio
2007
A. I can think of two options at least for "normal temp ranges", but must confess I know little about operation at such low temperatures. One is hard anodizing. The other one would be electroless nickel plating either hardened or as plated.
Guillermo MarrufoMonterrey, NL, Mexico
A. 4 Kelvin is incredibly cold. I think that the differences in the coefficients of thermal expansion is too great for hard anodize to work. I will question if EN will work for the same reason, especially in a vacuum. I think that you will probably have to go with titanium or stainless steel to work in that environment.
I would cold cycle it a couple of times before I used it as it very well might warp. Some things can be cryogenically hardened.
- Navarre, Florida
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