Novel C-Bond coating to enable light weighting of glass products

The production of glass is a highly energy intensive process consuming approximately 7 TWh of energy in the UK annually. Glass is a relatively dense material and therefore also consumes significant energy during transport.

One of the limitations in the use of glass is its strength. Being a brittle material, surface defects with dimensions in the order of microns can lead to catastrophic failure. If glass was stronger, less glass would be required to achieve the same strength in a given glass article, therefore reducing the energy required to make the article, reducing the energy to transport the article and reducing the weight of the structure required to support the article (e.g. building or vehicle support materials) further reducing the energy required for the overall structure.

C-Bond is an American Corporation that has developed a glass surface treatment that, in combination with a laminated film, provides significant increase in ballistic protection. The formulation uses a combination of additives, including modified silane molecules, surfactants with specific size distributions and carbon nanotubes to facilitate both mechanical keying and chemical bonding to the glass substrate. This not only forms a protective layer to prevent defects but 'holds' surface cracks together to prevent them propagating into the bulk.

Experimental work indicates potential strength increases of >200%, implying that the thickness of treated glass articles could be reduced by 50-60% and maintain strength. In reality there are more complex issues involved, for example the need to maintain rigidity, which this treatment would not affect, so the overall reduction is more likely to be 20-30%. However, if an average of 15% reduction could be achieved in all glass products in the UK then approximately 1 TWh would be saved annually.

This project aims to explore a range of glass applications to examine the potential benefit of apply C-Bond material to increase strength and thereby reduce energy use.

The primary focus will be on flat glass (architectural, automotive and aerospace) and containers (bottles and jars); these 2 sectors account for 90% of glass production in the UK. Other potential applications of this technology are domestic glass and pharmaceutical packaging; in both cases the interest will be to reduce breakage, rather than reduce weight.

THE ENERGY TRILEMMA (Security of supply, reduction in emissions, increased affordability) - Glass melting is an energy-intensive practice and rising fuel costs, CO2 emissions and energy consumption are driving innovation in this sector. The UK manufactures over 3MT of glass per year using c. 4.5 TWh of energy (mostly from natural gas, 50% of which is imported) at a cost of £70m, and is responsible for the atmospheric release of 2MT of CO2. If successful, this approach will help deliver against all three aspects of the energy trilemma: (i) by optimising nano-additives within the coating formulation to the scale of flaws within the glass surface, experimental work by Rice University indicates potential strength increases of up to >200% could be possible. Standard fracture mechanics methodologies indicate that this would realise an average of >50% weight reduction could be achieved in all glass products in the UK. If achieved, this would lead to energy savings in the region of 5-10%, equating to annual savings of up to 1 TWh, cost savings of £7-10m; (ii) t have associated reduction in UK CO2 emissions of up to 184kT/yr . Implemented EU-wide, this would give energy savings of c. 10-20TWh and cost savings of c. £38-77m p/a and CO2 savings of up to 1.8MT. (iii) Lighter glass products would result in a reduced drawn on current UK energy reserves in the manufacturing processes through reduced glass volumes requiring melting/greater output of products per furnace, thus improving security of UK energy supplies. The volume of raw materials required per product will also be reduced.