**1. Introduction**

Bronze, owing to its superior wear resistance is generally treated as one of the most commonly used engineering materials mainly as a bearing material in aerospace, automotive as well as industrial applications. Researches are being conducted on application of traditional coating methods like PVD, CVD, sputter deposition, electroplating, etc., for improving the surface properties of bronze. Surface modification process (SMP) has become an emerging technique to replace the traditional coating processes to improve the tribological properties of ferrous as well as non-ferrous alloys. In SMP, a heat source is used to melt the substrate surface and thereby a molten pool is formed. Then, the heat source is progressively moved along the length of the substrate so that, upon solidification a modified layer will be formed. In the case of fixed heat source, substrate will be moved. The major advantage of using SMP is that, the modified layer formed after solidification is integral to the substrate Benkisser et al. [1]. The applications of the alloys can be extended to ship propellers, sub-sea weapon ejection system, pumps, bearings and bushes as well. The drawback of traditional coatings getting delaminated on repeated cycles of operation can be omitted by using SMP. The formation of a functionally graded material (FGM) can be expected as a result of SMP. Since FGM is characterized by the gradual variation in composition and structure over volume, SMP with alloying elements results in the formation of an FGM. Wear

#### **Figure 1.**

*Surface modification process.*


#### **Table 1.** *GTA process variables.*

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**Figure 4.**

**Figure 3.**

*Cu-Sn alloy with and without Ni coating.*

*Cu-Sn alloy surface modified with Ni.*

*Development of Functionally Gradient Cu-Sn-Ni Alloy Using GTA Heat Source*

resistance, hardness, corrosion resistance, thermal conductivity, etc., of various alloys can be improved by the application of SMP. C Paul [2]. A schematic of SMP

This chapter discusses an investigation on the effect of Ni content on the hardness, the wear rate and the coefficient of friction of the surface alloyed Cu-Sn bronze alloy. As no previous works have been reported in the literature on the effect of Ni content on the hardness and the wear behavior of the surface alloyed bronze alloy, the present research work is undertaken. In the present study, the Sn content of the alloy was kept constant at 10 wt % and the Ni content was varied. The bronze substrates are coated with Ni of varying coating thickness (80, 120, 160 and 200 μm) using electroplating technique. The surface alloying process was carried out on the Cu-Sn bronze alloy coated with Ni. The GTA was used as the heat source. The GTA process variables, current (I), electrode diameter (eΦ), arc length (l), electrode angle (eθ), traverse speed (u) and argon flow rate are kept constant during the surface alloying process. The GTA process variables used in this study are reported in **Table 1**. The Ni concentration profiling was carried out for the surface alloyed samples. The Ni concentration was measured on the surface as well as along the depth of the modified layer formed in the surface alloying process using EDAX

*DOI: http://dx.doi.org/10.5772/intechopen.86315*

is shown in **Figure 1**.

**Figure 2.** *Experimental setup.*
