Toughened

Toughened describes a material that has been made more resistant to fracture and damage by a process that enhances its toughness. In materials engineering, toughness refers to the ability to absorb energy and deform without breaking. Toughened materials are designed to combine strength with improved resistance to crack initiation and propagation, making them safer or more durable in demanding applications. The term is used across glasses, polymers, ceramics, and composites.

In glass, toughened often means tempered glass. Tempering involves heating the glass to a high temperature and then cooling it rapidly. This creates compressive stresses on the surface and a tensile interior, significantly increasing bending strength and impact resistance. Toughened glass is commonly used for automotive windows, safety glazing, shower doors, and architectural facades. It is not possible to rework tempered glass by annealing, and if damaged, it tends to break into small, blunt fragments rather than sharp shards, though edge or surface damage can lead to catastrophic failure.

In polymers, toughening typically employs impact modifiers or dispersed secondary phases that absorb energy and blunt crack growth. This yields materials that are more resistant to impact and fracture, used in engineering plastics such as polycarbonates and modified acrylics, as well as in automotive and consumer applications.

In ceramics and ceramic matrix composites, toughness can be increased through microstructural design and transformation toughening, where phase changes during crack growth help deflect or arrest cracks. These approaches enable ceramic materials to achieve higher damage tolerance while retaining high hardness and heat resistance.