[time-nuts] Thermal time constant

[Bruce Griffiths]

Beryllium copper parts are also an issue although the beryllium content 
is only 0.3%-0.5% by weight.

Bruce

Bob Camp wrote:
> Hi
>
> The same caution applies to the beryllium in beryllium oxide heat spreaders. You find them in old RF transistors and some RF tubes.
>
> Bob
>
> On Mar 10, 2010, at 6:45 PM, Bruce Griffiths wrote:
>
>    
>> There's at least one known case where someone attempted to grind a beryllium mirror substrate using conventional methods without proper control of dust resulting in his death.
>>
>> Bruce
>>
>> Neville Michie wrote:
>>      
>>> Just in case anyone finds a beryllium brick somewhere and tries to use it:
>>> Beryllium is very very poisonous.
>>> cheers,
>>> Neville Michie
>>>
>>> On 11/03/2010, at 10:08 AM, Bruce Griffiths wrote:
>>>
>>>        
>>>> phil at pseng.org.uk wrote:
>>>>          
>>>>> Looking at the specific heat of metals:
>>>>> http://www.engineeringtoolbox.com/specific-heat-metals-d_152.html
>>>>> Wouldn't Beryllium be better instead of aluminium?
>>>>> I could foresee a few problems though eg machining holes at home, never mind where to get a block from.
>>>>>
>>>>> Phil
>>>>>
>>>>>            
>>>> Actually in this application minimising the volume of the metal block rather than its weight is probably better so one should use specific heat*density as a figure of merit.
>>>>
>>>> METAL            Specific heat*density (W/J/cubic cm)
>>>> Aluminium         2.46
>>>>
>>>> Beryllium            3.29
>>>>
>>>> Copper               3.49
>>>>
>>>> Silver                  2.41
>>>>
>>>> Iron                    3.87
>>>>
>>>> Thus copper and iron are better choices than Beryllium they also poses fewer machining diffculties
>>>>
>>>> Bruce
>>>>
>>>>
>>>> _______________________________________________
>>>> time-nuts mailing list -- time-nuts at febo.com
>>>> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>>>> and follow the instructions there.
>>>>          
>>>
>>> _______________________________________________
>>> time-nuts mailing list -- time-nuts at febo.com
>>> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>>> and follow the instructions there.
>>>
>>>        
>>
>>
>> _______________________________________________
>> time-nuts mailing list -- time-nuts at febo.com
>> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.
>>
>>      
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>
>