# Advanced Composite Materials: A Panacea for Improved Electricity Transmission
## 4 Robust Composite Materials for Transmission Conductors
### Al-CNTs  
CNTs have a high thermal conductivity of 4000 Wm\({}^{-1}\) K\({}^{-1}\), high modulus of 1 TP, and very low density of 1.7 g cm\({}^{-3}\). These excellent properties of CNTs can improve the properties of Al when used as its reinforcement. Reinforcing Al alloy with CNTs improves not only the strength but also the tribological, corrosion, thermal, and electrical properties. If the CTE of the two materials are considered, it will be observed that CNTs have CTE of  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Transmission Grid** & & **Manifestation/Damage** & **Prevention/Control** \\ \hline \multirow{4}{*}{Conductor defects} & (i) & Electrical treeing & (i) & Improved fabrication \\  & (ii) & Voltage drop & techniques \\  & (iii) & Frequent power outage & (ii) & Improved and \\  & (iv) & Low ampacity & & advanced nanomaterials \\ \hline \multirow{3}{*}{Overloading} & (i) & Grid instability & Reinforcing Al alloy with \\  & (ii) & Power outage & thermally stable materials \\  & (iii) & Explosion of the line & such as CNTs, BN, and TiC \\ \hline \multirow{4}{*}{Bushfire} & (i) & Lowers ampacity & Fire resistant nanomaterials \\  & (ii) & Speeds up ageing & should be alloyed to Al alloy \\  & (iii) & Reduces durability & in order to withstand high \\  & (iv) & Burns down the & temperature of flames \\  & & wooden supports & \\ \hline \multirow{4}{*}{Lightning} & (i) & Burns down the line & Use of high thermal \\  & (ii) & Power outage & conductive nanomaterials in \\  & (iii) & Explodes the line & alloying of Al to induce \\  & (iv) & Induces creep & speedy heat conduction \\ \hline \multirow{4}{*}{Extreme weather} & (i) & Excessive contraction and & Use of nanomaterials with \\  & & expansion of conductors & very low CTE such as CNTs in \\  & (ii) & Creep and ageing & reinforcing Al alloy as the \\  & (iii) & Decline in ampacity & conductor material \\ \hline \multirow{4}{*}{Short circuit} & (i) & Collapse of grid & Use of refractory material that \\  & (ii) & Explosion & would withstand very high \\  & (iii) & Fire & temperatures of over 200 \({}^{\circ}\)C \\  & (iv) & Power outage & \\ \hline \hline \end{tabular}
\end{table}
Table 3: Summary of transmission grid challenges and control.  
\(10\times 10^{-6}\) K\({}^{-1}\), while Al has CTE of 23.6 \(\times\) 10\({}^{-6}\) K\({}^{-1}\)[92], which is a very wide difference. So, during fabrication of Al-CNT composites, a great thermal mismatch occurs. This provokes huge dislocations at the interfaces that give rise to work hardening/strengthening of the composites. This is one of the basis of CNTs strengthening of Al. [PERSON] et al. [93] investigated the effect of CNTs addition into Al alloy and observed that the corrosion rate was tremendously reduced while the hardness of the composite improved. An increase in tensile strength by 129% was reported when 5 vol % CNTs was dispersed on Al [94]. Another study reported an increase in tensile strength and hardness by 184% and 333%, respectively, when 6.5 vol % CNTs were added to the Al matrix [95]. There was a reduction of corrosion rate by 46% and 47% in NaCl and H2 SO4 media, respectively, when 4 wt % CNTs were dispersed on Al [96]. In another study, when 4 wt % of CNTs were added to Al alloy, the coefficient of friction (COF) improved by 52%, the wear volume reduced by 23%, the thermal conductivity improved by 35%, and the electrical conductivity improved marginally by 2% [61]. Al-CNTs are therefore a potential conductor material capable of performing creditably in increasing power in the grid.