# Investigation of CuTi Alloy for Applications as Non-Sparking Material
## 3 Results and Discussions
### Analysis of Cu-Ti Samples After Severe Wear Tests for the Production of Explosive Sparks  
CuTi alloys as plates were clamped on a steel support and subjected to a forced wear resistance test for a number of 16,000 cycles. Material wear occurred in a potentially explosive enclosure between CuTi alloys and a multi-plate carbon steel support. Following the rubbing process, Figure 10a-f, the CuTi plates underwent various forms of wear, from local oxidation of the alloy to material removal both in the direction of wear and perpendicularly to it. Figure 10: _Cont._ \begin{table}
\begin{tabular}{c c c c} \hline \hline \multicolumn{1}{c}{**Alloy/Feature**} & **COF** & **AE** & **Ff** \\ \hline \multirow{2}{*}{Cu\({}_{2}\)Ti\_Cast} & 10N\_constant & 0.77 & 0.008 & 7.7 \\  & 10N\_linear & 0.18 & 0.002 & 1.01 \\ \hline \multirow{2}{*}{Cu\({}_{3}\)Ti\_Cast} & 10N\_constant & 0.16 & 0.001 & 1.6 \\  & 10N\_linear & 0.12 & 0.009 & 0.64 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Values of parameters COF, AE and Ff for experimental samples. Some of the CuTi plates were plastically deformed following the impact, and others were damaged close to the complete destruction of the plate. No hot sparks were formed during the wear process so the main conclusion of the wear resistance test was that this alloy can be considered an anti-sparking alloy for industrial applications in potentially explosive atmospheres. A transition of the CuTi alloy to the steel support is observed through the aggressive wear that occurred as well as the chipping of the steel in some areas following the tests. The tests were conducted under advanced wear conditions simulating all types of contact, from a fine contact at the beginning to an intense one at the end, covering most of the alloy exploitation situations under experimental conditions. At the microscopic level (Figure 11), the surface of the CuTi plates was examined by SEM, and it was found that there were material overlaps due to intense friction, macro and micro cracks, pores and oxidized areas. Figure 11: _Cont._  
Figure 10: Images of the CuTi plate surfaces after the severe wear test (16,000 contacts) for the production of explosive sparks: (**a**) the CuTi strips after wear on the fastening system, (**b**) the 6 rolled CuTi plates after severe wear (three of each Cu\({}_{2}\)Ti and Cu\({}_{3}\)Ti alloy), (**c**) different wear areas on the plates, (**d–f**) details of the differently worn areas and (**g–i**) details of the steel plates used for wear Cu-Ti alloy. From the chemical composition analysis of the CuTi plates, after the wear tests presented in Figure 12, besides the basic elements of the alloy (Cu and Ti), O and C were identified. From the chemical compositions determined, a slight oxidation of the surface of the alloy is observed (Table 6); through the applied accentuated wear, a reduction in Cu percentage on the surface replaced by the appearance of oxygen was observed. The Ti percentage did not decrease, compared to Cu, confirming the superior strength of the titanium oxide formed on the surface. From the element distributions shown in Figure 13, homogeneous surface wear is observed with material breaks, oxides and pores. Material breaks can be caused by the \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Zone/Elements**} & \multicolumn{2}{c}{**Cu\%**} & \multicolumn{2}{c}{**O\%**} & \multicolumn{2}{c}{**Ti\%**} \\ \cline{2-7}  & **wt** & **at** & **wt** & **at** & **wt** & **at** \\ \hline Zone 1 & 94 & 85 & 3.26 & 11.7 & 2.7 & 3.3 \\ Zone 2 & 91.5 & 77.2 & 5.95 & 19.9 & 2.53 & 2.83 \\ \hline EDS detector error \% & 2.2 & & 1.3 & & 0.2 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Chemical composition of severely worn plates. Figure 11: SEM images of CuTi lamellae surfaces after severe wear test for different areas: (**a**) 100\(\times\) and (**b**) 1000\(\times\). Figure 12: The energy spectrum identified by EDS analysis of CuTi plate surfaces after the wear resistance test and the appearance of sparks.