Nickel Sulphide Inclusions Flashcards
1
Q
What is Nickel Sulphide inclusion?
A
The mix of nickel and sulphate impurities in toughened or tempered glass. Once heated, the impurities expand and cause rapid failure of the glass.
2
Q
How does spontaneous glass fracturing due to nickel sulphide inclusions occur?
A
- Glass is heat treated the inclusions initially shrink
- Over time, inclusions gradually expand to their original size.
- This expansive force acts on the glass causing cracking.
3
Q
When is spontaneous glass fracturing due to nickel sulphide inclusions likely to occur?
A
- 1 year after manufacture there are few breakages.
- After this, the number increases for several years.
- Thereafter decreasing in frequency.
Fractures have occured more than 20 years after installation.
4
Q
How can Nickel Sulphide inclusion failures be identified?
A
- Pane cracks into small fragments.
- Distinctive butterfly shape at epicenter linked by a central straight crack.
- Inclusion may be visible
5
Q
How is glass tested for nickel sulphide inclusions?
A
Send sample of fractured glass intact with epicentre protected with clear film to a testing lab.
6
Q
How can glass fractures from nickel sulphide inclusions be mitigated?
A
- ‘Heat soaking’ is a quality controlled process.
- Glass is subjected to high temperatures allowing inclusions to expand.
- This allows fractures to occur in a controlled environment.
