Best Flashlight Material

[Flashlight Aficionado]

What is the best flashlight material? You need a conductive material to let the body conduct some electricity. The material has to transfer heat efficiently. Crush and scratch resistance is always a plus. Lighter weight makes EDC easier.

No price limit. I am just asking for amusement and to gain knowledge. Let's have some fun.

Gold - great conductor, easily scratched and crushed, very heavy and a great heat conductor. Not a great flashlight material.

 

[rayman]

Don't know what the best material for the heatsink is. But hard-anodized aluminium is really good for the body of the flashlight as it is relatively light and is really tough.

rayman

 

[Marduke]

In the aerospace world, there is just such a material called Wishalloy. It has all the properties you desire. The price is prohibitively expensive however, to the point of being unobtainable....

 

[Kestrel]

Beryllium (~3%) - copper alloy

• ~200k psi yield (~2x-3x that of 7000-series aluminum) so a very high strength-to-weight ratio
• Very high electrical and thermal conductivity, considerably higher than (precipitation-hardened) 7000-series Al.

I also wanted to drop in a table I put together earlier, since rayman mentioned heatsinks:

Thermal Specific _Den _"Thermal
conduct HeatCap _sity _volume"
(W / mK) (J / gK) (g/cc)_ (J/ccK)
​

Aluminum 250 __0.85 ___2.7__ 2.3
Brass..... 110 __0.38 ___8.6 __3.2
Copper... 400 __0.39__ 10.5__ 4.0
Silver..... 430 __0.23 ___9.0 __2.1
("thermal volume" is the heat that a fixed-size part such as a heatsink will absorb, per degree rise in temperature)

 

[wadus]

Kestrel, how expensive would a light made of that cost for the body? Also, is it corrosion resistant at all? I know copper corrodes pretty badly; the statue of liberty is a good example of why I ask.

 

[mmajunkie]

In the aerospace world, there is just such a material called Wishalloy. It has all the properties you desire. The price is prohibitively expensive however, to the point of being unobtainable....

Do your 7,591 other posts contribute this much?

 

[Kestrel]

Kestrel, how expensive would a light made of that cost for the body? Also, is it corrosion resistant at all? I know copper corrodes pretty badly; the statue of liberty is a good example of why I ask.

Probably pretty spendy, Be-Cu is being phased out of use due to toxicity issues related to the generation of fine Be particulates during machining.

Corrosion would be somewhat worse than pure copper due to the high distortion in the copper lattice from the Be-Cu intermetallic precipitates. However, the oxidized surfaces are pretty inert and are actually rather attractive, in a subdued sort of way.

 

[Gunner12]

What about multi layers? I'm thinking copper(or even silver) inner layer with coating on the very inside for chemical resistance and something and the outer layer will be something that holds heat well and the very outside will be something like Ti or Stainless steel or if the second layer is Al, good HA. I'm not sure how well the thermal transfer will work though. Contacts will be gold plated (and no contact through the threads).

 

[Blindasabat]

It's called unobtanium. The term we use around work for the material we want to use, but doesn't exist. "What's that made of, unobtanium?"

I'll second Beryllium. But more pure, not alloyed with Copper. Lighter than aluminum & less thermal conductivity, but compared to any other material even AL & copper, it has better thermal properties relative to its density (more thermal conductivity & capacity per given mass). It is stronger than AL of the same thickness. But very expensive - $745/kg (!) . And it is a carcinogen, so coat it in something! Don't breathe the machining dust!

From Wikipedia:

Beryllium has one of the highest melting points of the light metals. The modulus of elasticity of beryllium is approximately a third greater than that of steel (stiffer than steel). It has excellent thermal conductivity and is nonmagnetic.
At standard temperature and pressures beryllium resists oxidation when exposed to air.
Due to its stiffness, light weight, and dimensional stability over a wide temperature range (down to -240C), beryllium metal is used for lightweight structural components in the defense and aerospace industries in high-speed aircraft, missiles, space vehicles, and communication satellites. Several liquid-fueled rockets use nozzles of pure beryllium, such as the Saturn V.

"My flashlight is a missile!" :nana:

Beryllium Copper is good for a "normal" material:
"Beryllium copper is a ductile, weldable, and machinable alloy. It is resistant to non-oxidizing acids (for example, hydrochloric acid, or carbonic acid), to plastic decomposition products, to abrasive wear and to galling. Furthermore, it can be heat-treated to improve its strength, durability, and electrical conductivity.

 

[Sub_Umbra]

"Best" might be differemt for different types of lights. The self-lubricating qualities of brass make it nice for small pocket twisties...

 

[nzbazza]

Gold - great conductor, easily scratched and crushed, very heavy and a great heat conductor. Not a great flashlight material.

Gold has some advantages:

Major bling factor
If made from 24K gold, one could easily make the battery tube larger to fit an additional cell in...

What about Al-Li alloys? When compared to more standard 2xxxx and 7xxxx Al alloys, Al-Li alloys have

• 7-10% Lower density.
• 10-15% Higher Modulus.
• Excellent fatigue and cryogenic toughness properties.
• Higher stiffness.
• Superior fatigue crack growth resistance.
• Reduced ductility
• Low fracture toughness

For Al-Li alloy 2090
Density, 2.59 g/cm3
Melting range, 560-650 degC
Elastic modulus, 76 GPa
Poisson's ratio 0.34
Thermal conductivity at 250C, 84-92.3 W/m-k
Specific heat at 1000C, 1203 J/kg-k

 

[kramer5150]

Copper as mentioned above.
In a lot of the designs I review at work, if aluminum heatsinks do not provide sufficient thermal conduction we opt to spend more $$$ and go with copper.

FWIW, 316L and titanium (two very sought after boutique CPF materials) are both relatively poor thermal conductors. IIRC titanium behaves more like a thermal insulator.

 

[Kestrel]

The thing with Aluminum-lithium, yes some of the mechanical properties are improved, but the OP was asking for good thermal conductivity as well. Al-Li has only about 50% of the thermal conductivity of 6000-series Al.

 

[Marduke]

Do your 7,591 other posts contribute this much?

Swing and a miss.....

 

[Marduke]

The thing with Aluminum-lithium, yes it's strong enough, but the OP was asking for good thermal & electrical conductivity as well. Al-Li has only about 50% of the conductivity of 6000-series Al.

Some alloys of it are better than others. It's just harder to find published data on them due to their primary uses

 

[Kestrel]

Some alloys of it are better than others.

Yes, it's very difficult to generalize when talking about various alloy compositions of the same element. A co-worker of mine was one of the original developers of modern Al-Li, when the issue of Lithium diffusing out of the Aluminum lattice was solved.

 

[Patriot]

Some alloys of it are better than others. It's just harder to find published data on them due to their primary uses

Meaning weapons or aerospace....military and such? I noticed there was limited info on some of the metals discussed so far after trying to search them.

 

[Marduke]

Meaning weapons or aerospace....military and such? I noticed there was limited info on some of the metals discussed so far after trying to search them.

If they have not yet been consumerized, and/or used for applications which could be used for military purposes, information is withheld.


Al-Li 2195 is a good example that I have a great deal of experience with.

 

[Big_Ed]

Best can mean different things in different situations. For example, if you work outside in a cold climate, a metal flashlight might not be the best choice. A plastic or rubber one would be much more comfortable to hold. And it'll be lighter too.

 

[american lockpicker]

I like brass and stainless steel.