GENERAL CATEGORIES OF GLASS Flashcards
Most common type of glass encountered in volume measurements
Borosilicate
Composition of borosilicate
80% silica
13% boric oxide (BORON)
4% sodium oxide
2-3% Aluminum oxide
Characteristics
High degree of thermal resistance and low coefficient of thermal expansion
Borosilicate
– tendency of matter to change in shape, area, and even in volume, in response to a change in the temperature that it is subjected to
Thermal expansion
The low coefficient of thermal expansion also allows the manufacturing of these products –______ glasses – have heavy walls that will give it mechanical strength, even if it has thick or heavy walls, it will still retain reasonable heat-resistance
borosilicate
Low alkali content
Resistant to alkali corrosion
Borosilicate
Free of heavy metals
Free from Mg-lime-zinc group of elements, heavy metals, arsenic, and antimony
Borosilicate
Uses
Heating – open flame or electric heating elements
Borosilicate
It is at this point that all movement of the glass molecules has reached a point where no more strain can be introduced into the glass.
Strain point
Popular brands of borosilicate
Pyrex
Kimax
Pyrex: Strain point –
Kimax: Strain point –
515C (Henry)
513C
Silica fused to____
More expensive than borosilicate glass
quartz
High silica
Strengthened chemically rather than thermally
Alumina-silica or aluminosilicate glass
Aluminosilicate glass
With_____
aluminum oxide
Greater chemical durability and can withstand higher operating temperatures
Aluminosilicate
Compared to borosilicate,________ are more difficult to fabricate – thus it is not very common in the laboratory
aluminosilicates
When coated with an electrically conductive film,_______ glass is used as resistors for electronic circuitry
aluminosilicate
High-impact, extremely strong glass
Common use: manufacture of calibrated centrifuge glass
Centrifugal force tend to pull other glasses, thus_______ glass is utilized for centrifugation.
aluminosilicate
Popular brand/s of aluminosilicate
Corex
Characteristics;
✓ Radiation-resistant
✓ 6x stronger than borosilicate (outlast conventional glassware by 10-fold)
✓ Resist clouding and scratching better
Uses:
✓ High-precision analytical work
✓ Optical reflectors and mirrors
Not used as general type of glassware in the lab – a bit difficult to manufacture
Corex (Corning, N.Y.)
Aluminosilicate
Non-laboratory uses
Outermost layer of our phone screens
Aluminosilicate
Boron-free
AKA “soft glass”
Thermal resistant
Acid/ alkali resistant glass
Acid/ alkali resistant glass popular brand
Vycor (No. 7900)
made up of fused silica
2 in 1 characteristics – heat-resistant and chemically-inert
Unique characteristics
✓ Stable to all acids except hydrofluoric types
✓ Superior in resisting corrosion by alkali than borosilicate glass – no calibration markers
✓ Unlikely contamination by contact with solutions
✓ Relatively inert to acids and neutral salts
✓ Chlorine and acid gasses does not affect it at any temperature
Vycor
Alkali/ acid resistant glass
