**1.3 Difference between smart and composite material**

Though smart materials and composite materials sound similar, they are fundamentally different. Smart materials have a minimum dual function whereas composite materials consist of dual or more components/phases (thereby being called hybrid materials).

Smart materials serve various functions within one product, some common instances of which include actuator/sensor ability in addition to having form, having the ability to bear structural weight without breaking. The classic example having huge industrial value is Nitinol, an alloy of Nickel-Titanium. This material can be mechanically deformed like bent and can be returned to the pre-deformed shape by heating the material. Another good example of a smart material will be Lead-Zirconate-Titanate (PZT) which is a ceramic that mechanically deforms when an electrical potential is generated. PZT alloy has found an actuator application because a reverse potential produces expansion of the material geometrically (**Figure 2**).

As mentioned previously, composites consist of many different materials in two or more phases, which allow us to specifically engineer the composites to produce desired properties like enhancing mechanical stress, conductivity, etc. The

**Figure 2.** *Classification of composite materials with respect to matrices.*

compound will be considered a composite material as long as the base materials retain their physical morphology and characteristics.

