Silicate glasses are named as such because it is the empirical SiO2 unit that forms the majority of the glass structure. Silica is there for referred to as the network former. Unlike...
Borosilicate glass formulations give enhanced physical and chemical durability compared to soda-lime glasses commonly encountered as commercial container glasses. Borosilicate glasses are also frequently encountered in everyday life in the form of cookware and have become somewhat synonymous with the original tradename, Pyrex introduced in 1915. Many of us can attest first hand to the remarkable improvement in shatter resistance borosilicate glasses offer.
The addition of boron trioxide (B2O3) into the glass network allows the silica content to be increased in tandem, thus imparting the desired chemical and physical durability while still maintaining more moderate production temperatures. It is typically introduced by decomposition of boric acid (H3BO3) or boraxes.
When we consider the harsh chemical industries in which Glassflake is utilised the corrosion resistance of some of these formulations can still be found wanting. Further chemical resistance can be imparted by addition of materials such as alumina (Al2O3). In a continuous process as in glass manufacturing it is vital not only to consider the properties of the finished product but also the materials processability.
Most modern glass fibres are derived from an archetypical alumino borosilicate glass family known as E (electrical) glass. Named for their early applications based around the high electrical resistivity of the material, they are also commonly used to produce reinforced plastics composites. There are a number benefits to switching from a fibre to the Glassflake morphology in these two application and these are two topics we will revisit in future spotlights.
At Glassflake we have our own range of E-glass products as well as our best-selling ECR (extra chemical resistance) glass products that combines the mechanical strength, and high electrical resistivity of E-glass with greatly enhanced chemical resistance.
Next time we will explore how these different glass additives influence the glass on the molecular level to deliver the desired benefit.