GLASS NANO-CERAMICS

Depending on the size of the crystallites in relation to the wavelength of light, glass–ceramics can be designed to be either transparent (e.g., with nanoscale crystallites) or opaque (e.g., with micro-scale crystallites). 

When it comes to reinforcing any material system, one must look to nature for essential design cues.

Nature always seeks to lower the energy required for any reaction or given event to occur. With this in mind, it is possible to play on this effect, to make it harder for a given process to initiate and propagate. In glass, that would be crack formation and propagation. When a load is applied to a material, it imparts a large amount of energy on the material, creating a situation wherein the material now needs to respond to this energy. Beyond the elastic limit, a brittle material such as a glass or ceramic would normally dissipate this energy through the formation of new surfaces  e.g. through crack formation.

Glass–nanoceramics offer a versatile range of beneficial properties to enhance the fracture toughness glass. The physical presence of ultrafine, well dispersed nanocrystallites serve as prohibitors to crack propagation.  This happens because whenever a propagating crack encounters a nanocrystal interface, the crack must either change its propagation direction to move around the nanocrystal or initiate a new crack through the crystallite phase itself.  

However, when the nanocrystal is small enough to even limit the formation of a grain boundary within its crystal lattice, the probability of a fault site is all the more limited. Such a frustration to the natural process of things creates such a huge energy barrier that the formation of a path for crack propagation, leads to an energetically unfavourable scenario and fracture is limited or prohibited altogether. 

HIGH STRENGTH AT LESS WEIGHT

For the propagation of a crack to be significantly limited around and within a nanoceramic crystal infused in glass (glass-nanoceramic), these fundamentals are essential:

• A uniform and dense dispersion of the nano-ceramic crystals within the glass matrix is crucial

• The nano-ceramic crystals need to be well below 20 nm in dimension, to minimise or prevent grain boundary formation within itself

• The nano-ceramic crystal composition needs to confer versatile functionality e.g.  chemical, optical, electrical properties to the glass that help it obtain and retain durability

A major challenge encountered during the preparation of glass-nanoceramic matrix nanocomposites, is the ability to achieve a homogeneous dispersion of nanocrystals, therein.  Micrometer-sized clump agglomeration of in particular large nanoparticles (often > 30 nm in size) used in heavy loads tend to generate adverse effects on the thermal and mechanical properties of the glass, as a smaller number of reinforcing particles are present in other areas and aggregates may act as defect centers, which can act as crack initiators that lead to structural failure of the glass composite.

NANO-CERAMIC PARTICLE SIZE CONTROL MATTERS

By reducing nano-ceramic particle size well below 20 nm, one can influence the number of dislocations piled up at a grain boundary and enhance the yield strength of a nanoceramic i.e. the maximum stress the nano-ceramic crystal tolerates before deformation begins. 

Distribute a significant amount of these within a glass matrix and one obtains a high density of reinforcement sites, within a glass matrix. This is easy with ultrafine nano-ceramic particles because the average number of them present within a unit volume of material increases exponentially, as the particle size reduces. e.g. a 1 um sized ceramic particle can be replaced by about a thousand  1 nm sized nanoceramic particles. This implies that with less volume and mass, a higher density distribution of nano-ceramic particles can be achieved within a glass matrix, at a significantly lower dose than obtained with micronised or even larger (> 20 nm) particles.

CHEMICALLY NANO-TEMPERED GLASS

Glass fracture inevitably has its origin at the nanoscale (i.e. bond breaking). Chemical tempering is a very effective method of improving strength via the  incorporation of a high compressive stress in the surfaces of the glass. A topologically optimisation design of glass at the nanoscale level can be achieved, using nano-ceramic crystals of varying composition, in combination with the nano-ceramic crystal dimension benefits, to enable energy applied to a glass surface to be dissipated through localised densification around an indenter, rather than through crack formation within the glass itself.

With a core expertise in the design and manufacture of sub 20 nm sized nano-ceramic crystals, NANOARC is well positioned to help the glass industry push the envelope on glass performance in terms of chemical and structural durability. Being in the business of nano-polymorphism as part of a our nanomaterial design process, we make it possible for manufacturers to seamlessly adopt our products, without chemical compatibility concerns.

OUR  SOLUTIONS

Our solutions consist of high surface area nanopowders with carefully chosen chemical compositions, strategically selected nanoparticle size to benefit from quantum effects and redefined crystal structure, to wield the strength of nanoarchitecture, for unique and heightened functionality.

With our atomically-architectured ultrafine nanopowders, we enable the development of high-performance glass systems with feature augmentations such as:

• Enhanced optical transparency for improved microscopy and energy harvest

• Tailored optical properties

• Higher mechanical strength at  lighter weight and low porosity 

• Enhanced thermal transport for energy conservation

• Stain-resistance

• UV filtering with transparency

• Antimicrobial and anti-fungal protection without requiring photo-activation

• Attenuation of ionising nuclear radiation