| Summary: | 碩士 === 國立臺灣科技大學 === 機械工程系 === 106 === This study elucidates the effect of the percentage of Y2O3 on the microstructure and tribological performance of Ti-6Al-4V that is clad in SiC and Ni powder, using gas tungsten arc welding(GTAW). The microstructure, reinforcing phase, mechanical properties were analyzed using SEM, EDS, XRD, EPMA, Vickers hardness tester and Nanoindenter. In addition, a pin-on-disc rotating tribometer was used to evaluate he wear resistance of the substrate and the clad specimens.
According to the experimental results, TiC and TiSi2 precipitates are formed in situ in the clad layer during the cladding process. Adding a suitable amount of Y2O3 promotes the formation of reinforcing phases, but an excessive amount of Y2O3 reduces the formation of reinforcing phases.
The wear test results indicate that all the clad layers improve the wear resistance of Ti-6Al-4V, and the wear resistance of the clad layer that contained Y2O3 is better than that of the clad layer without Y2O3. Under the condition of contact stress of 263 MPa, the 80%SiC+17.5%Ni+2.5%Y2O3 clad layer has the best wear resistance because the wear loss of 80%SiC+17.5%Ni+2.5%Y2O3 clad layer is the lowest among all the clad layers. Under the condition of a contact stress of 339 MPa, the 80% SiC+15.5%Ni+4.5%Y2O3 clad layer has the best wear resistance because the formation of plenty of reinforcing phases, which reduce the wear loss of the 80%SiC+15.5%Ni+4.5%Y2O3 clad layer.
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