# Investigation of CuTi Alloy for Applications as Non-Sparking Material
## 3 Results and Discussions
### Microhardness and Coefficient of Friction Analysis of Cu\({}_{2}\)Ti and Cu\({}_{3}\)Ti Alloys
The hot rolling process improves the porosity, morphology, inclusion distribution and mechanical properties due to the more uniform grain distribution. The characteristic friction coefficient (COF) of the alloys studied was determined by scratch tests (Figure 9). \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multicolumn{1}{c}{**Alloy/Area/Property**} & \multicolumn{2}{c}{**Young’s Modulus of Indentation (GPa)**} & \multicolumn{1}{c}{**Hardness**} & \multicolumn{1}{c}{**Contact Depth**} & \multicolumn{1}{c}{**Contact Stiffness**} & \multicolumn{1}{c}{**Contact Surface (\(\mu\)m\({}^{2}\))**} \\ \hline \multirow{6}{*}{Cu\({}_{2}\)Ti\_Cast} & 1 & 65.9 & 1.56 & 4.7 & 5.9 & 5773 \\  & 2 & 40.11 & 1.7 & 4.3 & 3.6 & 5312 \\  & 3 & 45.14 & 1.8 & 4.1 & 3.9 & 5072 \\  & 4 & 56.1 & 1.6 & 4.44 & 5 & 5519 \\  & 5 & 57.3 & 1.6 & 4.5 & 5.1 & 5547 \\ \cline{2-6}  & M (StDev) & 52.91 (\(\pm\)9.2) & 1.7 (\(\pm\)0.1) & 4.4 (\(\pm\)0.2) & 4.7 (\(\pm\)0.8) & 5445 (\(\pm\)237) \\ \hline \multirow{6}{*}{Cu\({}_{3}\)Ti\_Cast} & 1 & 107.5 & 1.68 & 4.3 & 9.1 & 5371 \\  & 2 & 80.5 & 1.77 & 4.1 & 6.8 & 5100 \\  & 3 & 73.6 & 1.93 & 3.8 & 5.9 & 4665 \\  & 4 & 107.7 & 1.6 & 4.5 & 9.3 & 5633 \\  & 5 & 111.75 & 1.56 & 4.7 & 9.7 & 5787 \\ \cline{2-6}  & M (StDev) & 96.2 (\(\pm\)15.9) & 1.7 (\(\pm\)0.1) & 4.3 (\(\pm\)0.3) & 8.2 (\(\pm\)1.5) & 5311 (\(\pm\)399) \\ \hline \multirow{6}{*}{Cu\({}_{3}\)Ti\_Hot-rolled} & 1 & 116.6 & 1.59 & 4.58 & 10 & 5679 \\  & 2 & 74.3 & 1.76 & 4.1 & 6.3 & 5122 \\ \cline{1-1}  & 3 & 115.3 & 1.52 & 4.8 & 10.1 & 5926 \\ \cline{1-1}  & 4 & 74.2 & 1.52 & 4.7 & 6.7 & 5909 \\ \cline{1-1}  & 5 & 59.8 & 1.7 & 4.3 & 5.2 & 5294 \\ \cline{1-1} \cline{2-6}  & M (StDev) & 88 (\(\pm\)23.4) & 1.6 (\(\pm\)0.1) & 4.5 (\(\pm\)0.3) & 7.7 (\(\pm\)2) & 5586 (\(\pm\)325) \\ \hline \hline \end{tabular}
\end{table} 
Table 4: The main mechanical characteristics extracted from the indentation test (5 indentations were made in various areas on the surface and averaged in the sixth line and the standard deviation is given in parentheses). Figure 9: Variation of coefficient of friction (COF) (**a**,**b**) for Cu\({}_{2}\)Ti and (**c**,**d**) for Cu\({}_{3}\)Ti. Two types of stress were applied, with the values obtained for the friction coefficient, acoustic emission and friction force being presented in Table 5, with constant force (in the case of this mode of stress, the support will move up and down as it is required to maintain a constant force) and with linear force (when this request mode is selected, a linear force (Fz) is applied as a function of time, the force value will change linearly from the initial value set by the user to final value depending on the duration of the experiment; this mode of application is often used to determine the critical load). The highest friction coefficient was presented by the cast Cu\({}_{2}\)Ti alloy for a constant stress of 10 N. For the Cu\({}_{3}\)Ti alloy, where an increase in stiffness was observed, a significant decrease in the friction coefficient and friction force was noted regardless of the stress type applied. Regarding spark production, materials with a lower friction coefficient can be considered, but the formation of hot sparks does not depend only on this aspect.