Coefficient Of Thermal Expansion Puns

I was looking at some structural materials for high temperature work and some of them have excellent structural strength at extreme temperatures (tungsten alloys) and some have great resistance to corrosion (pyrolitic boron nitride, various superalloys) or different electrical properties (hexagonal boron nitride is an an electrical insulator at refractory temperatures even when other ceramics become ionic conductors.)

Say you want to coat tungsten or copper tungsten with boron nitride or nickel. How far apart can the coefficient of thermal expansion be between coatings materials and the material being coated without the coating falling off or breaking? Tungsten has a low thermal expansion coefficient for a metal, but it's still significantly higher than some of the most corrosion resistant ceramics while also being significantly lower than a lot of nickel superalloys.

Say we want to coat a pipe that needs to stand up to pressure.

Hello, i have to do a calculation and use the coefficient of thermal expansions of Hg, K and Na. But i don't seem to find in google.And there is a book suggested Liquid Metals by Mitsuo Shimoji but i am not in a place to afford that book at it isn't availale to my place? Can somebody help with the data??

I have an exercise:

Calculate the thermal expansion coefficient of a material that has been compressed to 80% of its original volume, assuming that the ambient pressure value of α is 3 x 10-5 K -1 and that the Anderson-Grüneisen parameter, δT =1.47.

I tried to solve it the following way (I am looking for α0):

α/α0=(V/V0)^δT

Obviously I rearranged it, I know V/V0, δT and α, and I got a final result of 4.16*10^(-5), but according to my professor this is wrong. "Your answer to this was nearly correct - your method was right, but you made a careless mistake in getting the final result - remember that alpha at high P must be smaller than at room P, i.e. as V gets smaller so does alpha (in your answer it did the opposite). "

So what should I do different? I am not a big physics fan so it might be an obvious answer just I am too dumb to understand it. Thanks in advance!

For example the coefficient of volume expansion of aluminum is 7.2 x 10-5 k-1 how can one convert into coefficient linear thermal expansion.

title.

So, science apparently doesn't have a good answer for why invar has such a low thermal expansion coefficient. Since I've been learning about fusion and nuclear binding energies recently, I'm curious if there's any relation between the two phenomena here.

Hey guys,

I have already heard of certain materials that have a negative coefficient of thermal expansion. But are there any metals that shrink when exposed to higher temperatures?

I've been out of the physics/chemistry world too long and my inability to figure this out makes my old TI-89 sad.

I'm installing a composite deck. Due to thermal expansion, the instructions to leave a quarter inch gap on all sides of the planks. Makes perfect sense!

I'm trying to make it fancy and make a square out of a board with mitered 45 degree corners in the center of the deck (about 3 ft wide). I'm trying to calculate the smallest gap I can allow for the mitered corners. The data sheet for the board states that the expansion is 35.2 x 10-6 to 42.7 x 10-6 (inch/inch/°F). The units have me stuck.

Thanks for the help!

The question is for a rod of length 10cm, with no other dimensions given. the length expansion is 1mm, and the expansion is isotropic (i.e. the same in every direction). How can I calculate the volumetric thermal expansion coefficient, without knowing the initial volume?

I was wondering if there was a way at all to set the the above two coefficients in dsmcFoam+ for any of the wall boundary patches. If not, is there is default value already set, or if simply implementing a particular wall patch implied a certain value of these coefficients? Any guidance in pointing me to the right resources to look up would be appreciated. Thanks

Edit: It seems that the reflected molecules in the dsmcDiffuseWall patch are set to be fully accommodated with the wall temperature by default. Looking into the dsmcDiffuseWallPatch.c file, I notice that the setProperties function has the option of setting a fomrationLevelTemperature. Can the thermal accommodation coefficient then be defined with the above quantity set to a fraction of the wall temperature?

Background: I work in a thermal analysis/characterization lab and was just asked if my instruments could measure CME. Doing some research I found that one instrument (DMA) could measure CHE if we bought a humidity accessory for it. They seem to measure the same thing (expansion with moisture absorption), but the CME measurement method I read used a dilatometer and the moisture absorbed was measured by mass change rather than the relative humidity of the test chamber (after the sample is given plenty of time to equalibrate). Is there any difference in CME and CHE? If so what specifically?

Hi, I often switch between PLA and PETG on my FLSUN Q5.

Usually for PLA I use 210/45°C while for PETG 245/90°C.

The Q5 user manual doesn't mention to heat up the nozzle and bed when doing the Z0 calibration. As a beginner I did so and it worked fine for PLA, while I learned the hard way that for PETG the higher temperatures cause larger thermal expansion and so the nozzle will likely drag on the plate.

So, as a lesson learned, I now repeat the Z0 cal. with hot nozzle / bed with the temperatures that I'm going to use for the loaded filament.

This works fine (if you remember to do it) but it requires more time every time you change material.
If you forget to do it, you will end up with the nozzle dragging or printing too high.

I was wondering why FLSUN did not implement a temperature compensation for the Z0 position.

After all the thermal expansion shall be very well predictable for a given printer model.

Do you know other manufacturer implementing such feature?

As I workaround I was thinking to raise a little the first layer in the slicer for the profile that I use for PETG ... but I'm not sure this is a good idea and I have yet to try.

Thanks!

Also I had a doubt, NS sir in his IUPAC nomenclature was talking about new and old IUPAC rules and sometimes it is confusing. Should I ignore the fact whether it is old or new and just Learn what sir teaches ?

So there’s f(x) = (x^3 - x + 1)^187 and I have to find the sum of all coefficients behind even powers (e.g. x^2, x^4). I know that for any given binomial (a-b)^n the sum of all coefficients would be 0, and for (a+b)^n we have to use Pascal’s triangle to find the coefficients, but I’m not sure how to tackle a trinomial expansion like this. I would try the multinomial theorem, but the power is too big to compute with. Any ideas?

I don't know where to go for starting heat transfer coefficients (convective and contacts specifically). It's been a couple years since I sold my heat transfer books.

One set of variables I would like in particular are the contacts between components. Currently we are just using bonded contact, and I know that's a bit of stretch. A resource with some ranges for different contacts between different materials would be great.

If anyone has a resource they can recommend I would greatly appreciate it! A book on amazon perhaps?