more glass tech notes

[wombat1138]

Mostly working notes as I try to hash out the whole COE thing.

COE= coefficient of thermal expansion; usual stats (units?):

Pyrex: 33
Moretti/Effetre: 104
Bullseye: 90

From Wikipedia--

α : coefficient of linear thermal expansion; table scaled as [10⁻⁶/°C @ 20 °C]
α (borosilicate) = 3.3 x 10^-6/K -- is this simply rescaled to 33 X 10^-7/K?

Boro misc stats from here--

150°C - When working above this temperature care should be taken to heat and cool Borosilicate glass in a slow and uniform manner.
500°C - The maximum temperature that Borosilicate glass should be subjected to and then only for short period of no longer than a few minutes.
510°C - Temperature at which thermal stress can be introduced to Borosilicate glassware.
565°C - Annealing temperature. When uniformly heated in controlled conditions, such as a kiln or oven thermal stress’s can be removed.
820°C - Softening point at which Borosilicate may deform.
1252°C - Working point, the temperature that glassblowers need to attain in order to work Borosilicate glass.

boro annealing point ~565°C ; for rt = 20°C, delta(T)= ~545K -> total linear expansion 0.0017985, or ~0.18% from annealing point to rt?

Effetre/Moretti misc stats from here--

Coefficient of Expansion (COE): 104
Annealing range: 920 - 968º F (~968°F = 520°C)
Strain Point: 840º F (448.9°C)
Softening point: 1050º F (565.5°C)
Working Temperature: 1400º F (760°C)

-- COE 104 -> α = 104 X 10^-7/K -> 1.04 X 10^-5??

for delta(T)=500°C, total linear expansion = 0.0055 = 0.55%?

Bullseye site info: COE is range-dependent (~nonlinear?), but usually measured for the solid state from 0-300 C -- not entirely useful because it doesn't extend all the way up to annealing temperature. Standard manufacturers' COE stats tend to be imprecise and mostly useful for internal factory use and giving a *general* sense of compatibility

Bullseye misc stats from here:

	Transparents	Opals	Gold Pink Transparents
Strain point:	920°F (493°C)	865°F (463°C)	820°F (438°C)
Annealing point:	990°F (532°C)	935°F (501°C)	882°F (472°C)
Softening point:	1250°F (677°C)	1270°F (688°C)	1180°F (638°C)

Comments

[http://users.livejournal.com/jane_drew_/]

*reads COE as "Church of England"*

*baffled*

*intrigued*

*baffled some more*

*inexplicable desire for tea and cake or death*

[wombat1138.livejournal.com]

*ponders Henry VIII petitioning for his marriage to be annealed*