# Study on Wear Resistance of Ti-6 Al-4V Alloy Composite Coating Prepared by Laser Alloying
## 3 Results and Discussion
### Impact of Load Variation on Friction and Wear Properties
#### 3.2.4 Effect on Wear Morphology  
Figure 8a,c,e show the wear surface morphology of Ti-6 Al-4V alloy under 3 N, 6 N and 9 N load, respectively, Figure 8b,d,f are their partial magnification. From Figure 8a,b that the wear marks showed obvious furrow morphology and plastic deformation. In Figure 8c,d, there was not only a clear furrow, but also some wear debris. As the load increased, the normal stress and shear force applied on the surface of the Ti-6 Al-4V alloy increased, the Ti-6 Al-4V titanium alloy underwent significant plastic deformation, and adhered to the Si\({}_{3}\)N\({}_{4}\) ceramic ball, partially plastically deformed soft metal and protrusions. The hard spots were separated from the Ti-6 Al-4V titanium alloy under the action of shear force, which caused abrasive wear during friction during shedding. A deep grinding furrow on the wear surface as shown in Figure 8e,f, and there was some metal stripping near the furrow edge. Figure 9 shows the wear cross-section trajectory curve of Ti-6 Al-4V alloy when the load was 9 N. It was obvious that the wear depth was larger in the middle part, while it was shallow at the edge, because when the load was 9N, the force on the surface of Ti-6 Al-4V alloy was larger. According to the wear cross-section trajectory curve of Ti-6 Al-4V alloy, the wear depth and width increase with the increasing load, and the depth increase was larger. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Load (N)** & **Wear Width b (mm)** & **Wear Depth h (mm)** & **Wear Volume \(V_{W}\) (mm\({}^{3}\))** &
\begin{tabular}{c} **Specific Wear Rate** \\ **(mm\({}^{3}\cdot\)N\({}^{-1}\cdot\)m\({}^{-1}\))** \\ \end{tabular} \\ \hline
3 & 0.833 & 8.240 \(\times\) 10\({}^{-3}\) & 0.0686 & 0.048 \(\times\) 10\({}^{-3}\) \\
6 & 0.878 & 15.961 \(\times\) 10\({}^{-3}\) & 0.1401 & 0.049 \(\times\) 10\({}^{-3}\) \\
9 & 1.144 & 25.376 \(\times\) 10\({}^{-3}\) & 0.2903 & 0.067 \(\times\) 10\({}^{-3}\) \\ \hline \hline \end{tabular}
\end{table} 
Table 4: The wear width, depth, volume, and specific wear rate of alloying coating under different load. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Load (N)** & **Wear Width b (mm)** & **Wear Depth h (mm)** & **Wear Volume \(V_{W}\) (mm\({}^{3}\))** &
\begin{tabular}{c} **Specific Wear Rate** \\ **(mm\({}^{3}\cdot\)N\({}^{-1}\cdot\)m\({}^{-1}\))** \\ \end{tabular} \\ \hline
3 & 0.978 & 11.796 \(\times\) 10\({}^{-3}\) & 0.1154 & 0.080 \(\times\) 10\({}^{-3}\) \\
6 & 1.100 & 23.169 \(\times\) 10\({}^{-3}\) & 0.2549 & 0.089 \(\times\) 10\({}^{-3}\) \\
9 & 1.278 & 37.386 \(\times\) 10\({}^{-3}\) & 0.4800 & 0.111 \(\times\) 10\({}^{-3}\) \\ \hline \hline \end{tabular}
\end{table} 
Table 3: The wear width, depth, volume, and specific wear rate of Ti-6 Al-4V alloy under different load. Figure 10 shows the wear surface morphology of alloying coating under 3 N, 6 N, and 9 N load at room temperature. From Figure 10a,b, it can be seen that when the load was 3 N,  
Figure 8: Wear morphology of Ti-6 Al-4V alloy under different load. (**a,b**): 3 N; (**c,d**): 6 N; (**e,f**): 9 N.  
Figure 9: Wear cross-section trajectory curve of Ti-6 Al-4V alloy under different load. the wear surface was smooth, the furrow was shallow, the degree of plastic deformation was small, and the metal at the furrow edge was not inclined from breaking away from the friction surface. As shown in Figure 10c,d, when the load increased to 6 N, the furrow was deepened, there was a slight plastic deformation on the wear surface, and a small amount of metal broke away from the surface, resulting in increased grinding particles on the wear surface. As shown in Figure 10e,f, the depth of the furrow increased with the increasing load, debris on the wear surface also increased.