Designing with Thermal expansion in mind

[_Bd_]

Hi, I am trying to design a tubular probe that's made of stainless steel (304), from what I've read it has a Thermal expansion coefficient of around 9.6 x10^-6 in/in/F give or take on the quality.

I want to fill this tube halfway with an Epoxy, however from what I've read this epoxy has a thermal expansion coefficient of 21 x10^-6 in/in/F

This is more than twice as much expansion, and I'm worried that it will create stress in the part and might even break it.

However, what I want to know is if the expansion would happen side-ways given that it will be inside the tube and taking the shape of the container, I would hope that it would expand upwards mostly, since it would be limited on all other sides. I am not too sure about how things expand when restrictions are applied.

Please advice and thank you!

(Also if you know of some other epoxy that's RoHS and closer to the coefficient of SS that would help as well)

 

[berkeman]

Hi, I am trying to design a tubular probe that's made of stainless steel (304), from what I've read it has a Thermal expansion coefficient of around 9.6 x10^-6 in/in/F give or take on the quality.

I want to fill this tube halfway with an Epoxy, however from what I've read this epoxy has a thermal expansion coefficient of 21 x10^-6 in/in/F

This is more than twice as much expansion, and I'm worried that it will create stress in the part and might even break it.

However, what I want to know is if the expansion would happen side-ways given that it will be inside the tube and taking the shape of the container, I would hope that it would expand upwards mostly, since it would be limited on all other sides. I am not too sure about how things expand when restrictions are applied.

Please advice and thank you!

(Also if you know of some other epoxy that's RoHS and closer to the coefficient of SS that would help as well)

Depending on the application, you can use a buffer material between the epoxy and the SS to absorb the difference in thermal expansion. We have used Sylgard for this application in the past with good results (it's a softer polymer that is used for mechanical buffering in electronic applications):

http://www.dowcorning.com/applications/search/products/details.aspx?prod=01064291