本文將不同比例之稀土元素氧化釔(Y2O3)添加至主要陶瓷粉末碳化矽(SiC)及金屬粉末(Ni)當中混合均勻，進行氬銲被覆(Gas tungsten arc welding；GTAW)於Ti-6Al-4V鈦合金表面，探討不同比例之稀土元素對顯微組織、機械性質的影響，接著使用迴轉式磨耗試驗機以銷對盤(Pin-on-Disc)的線接觸方式進行磨耗試驗，評估被覆層的耐磨耗能力。
研究結果顯示，當碳化矽粉末(SiC)與不同比例(0%、2.5%、4.5%、6.5%)之氧化釔(Y2O3)混合時，所形成的被覆層皆會臨場(in-situ)合成TiC顆粒狀、樹狀析出物及TiSi2塊狀析出物。隨著氧化釔的添加，析出物數量增加且密集，但過量的氧化釔，卻會導致析出物的量減少。
磨耗試驗顯示不同成份的被覆層皆能改善Ti-6Al-4V鈦合金表面的耐磨耗能力，而且添加氧化釔有助於提升耐磨耗能力。在最大接觸應力263MPa的條件下，80%SiC+17.5%Ni+2.5%Y2O3被覆層有最佳的耐磨耗能力，因其H/E值為所有被覆層中最高，意即接觸表面受力後易產生彈性變形，而降低真實接觸應力，因此其磨耗量最低且摩擦係數穩定；在最大接觸應力339MPa的條件下，80%SiC+17.5%Ni+4.5%Y2O3被覆層有最優的耐磨耗能力，因強化相的密集分佈，使其磨耗量最低。

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.

1. K. Holmberg and A. Matthews, “Coatings tribology: properties, techniques and applications in surface engineering”, Amsterdam, Elsevier, 1994.
2. 周長彬、蘇程裕、蔡丕椿、郭央諶，銲接學，全華圖書股份有限公司
3. J.F. Lancaster, “Metallurgy of welding”, London, Chapman & Hall, 1993.
4. S. Lu, H. Fujii, H. Sugiyama, M. Tanaka and K. Nogi, “Weld penetration and Marangoni convection with oxide fluxes in GTA welding”, Materials Transactions, vol. 43, no. 11, pp. 2926-2931, 2002.
5. C.R. Heiple, J.R. Roper, R.T. Stagner and R.J. Aden, “Surface active element effects on the shape of GTA, laser and electron beam welds”, Weld. J., vol. 62, no. 3, p. 72, 1983.
6. J.P. Schaffer, A. Saxena, S.D. Antolovich, T.H. Sanders and S.B. Warner, “The Science and Design of Engineering Materials”, USA, WCB/McGraw-Hill, 1999.
7. “Material Properties Charts”, available at: http://www.micro-ceramics.co.il/Materials_f.htm, Israel, 2012
8. 林育奇，Ti-6Al-4V合金表面被覆陶瓷粉末之微結構及磨耗行為研究，國立臺灣科技大碩士學位論文，2010
9. F. Weng, H. Yu, J. Liu, C. Chen, J. Dai and Z. Zhao, “Microstructure and wear property of the Ti5Si3/TiC reinforced Co-based coatings fabricated by laser cladding on Ti-6Al-4V”, Optics & Laser Technology, vol. 92, pp. 156-162, 2017.
10. 鄭子樵、李紅英，稀土功能材料，曉園出版社，2006
11. J. Li, H. Wang, M. Li and Z. Yu, “Effect of yttrium on microstructure and mechanical properties of laser clad coatings reinforced by in situ synthesized TiB and TiC”, Journal of rare earths, vol. 29, no. 5, pp. 477-483, 2011.
12. 曾士榮，AISI 1020低碳鋼表面被覆氮化矽陶瓷粉末及合金元素添加不同比例稀土元素氧化釹之微結構與耐磨耗研究，國立臺灣科技大學碩士學位論文，2016
13. Y. Ma, H. Zhu, C. Sun, B. Liao, L. Shen, B. He, W. Zhu and X. Wang, “Microstructure and Properties of Y2O3-doped Laser Cladded Composite Coating on TC4 Titanium Alloy”, Surface Technology, vol. 46, pp. 238-243, 2017.
14. T. Chen, D. Liu, F. Wu and H. Wang, “Effect of CeO2 on Microstructure and Wear Resistance of TiC Bioinert Coatings on Ti6Al4V Alloy by Laser Cladding”, Materials, vol. 11, no. 1, p. 58, 2017.
15. G.E. Dieter, “Mechanical metallurgy”, New York, McGraw-Hill, 1988.
16. 劉國雄、林樹均、李勝隆、鄭晃忠、葉鈞蔚，工程材料科學，全華科技圖書股份有限公司，1996
17. D.R. Askeland and P.P. Phule, “Essentials of Materials Science and Engineering”, USA, Cengage learning, 2004.
18. K.H. Zum Gahr, “Microstructure and wear of materials”, Elsevier, 1987.
19. G.W. Stachowiak and A.W. Batchelor, “Engineering TriBology”, Elsevier, 2014.
20. T.F.J. Quinn, J.L. Sullivan and D.M. Rowson, “Origins and development of oxidational wear at low ambient temperatures”, Wear, vol. 94, no. 2, pp. 175-191, 1984.
21. T.F.J. Quinn and W.O. Winer, “An experimental study of the “hot-spots” occurring during the oxidational wear of tool steel on sapphire”, Journal of Tribology, vol. 109, no. 2, pp. 315-319, 1987.
22. C. Lifang, Y. Zhang and S. Likai, “Microstructure and formation mechanism of titanium matrix composites coating on Ti-6Al-4V by laser cladding”, Rare Metals, vol. 26, no. 4, pp. 342-346, 2007.
23. T.F.J. Quinn, “Computational methods applied to oxidational wear”, Wear, vol. 199, no. 2, pp. 169-180, 1996.
24. T.F.J. Quinn, “Oxidational wear modelling: I”, Wear, vol. 153, no. 1, pp. 179-200, 1992.
25. T.F.J. Quinn, “Oxidational wear modelling: Part II. The general theory of oxidational wear”, Wear, vol. 175, no. 1-2, pp. 199-208, 1994.
26. T.F.J. Quinn, “Oxidational wear modelling Part III. The effects of speed and elevated temperatures”, Wear, vol. 216, no. 2, pp. 262-275, 1998.
27. T.F.J. Quinn, “The oxidational wear of low alloy steels”, Tribology International, vol. 35, no. 11, pp. 691-715, 2002.
28. M. Vardavoulias, “The role of hard second phases in the mild oxidational wear mechanism of high-speed steel-based materials”, Wear, vol. 173, no. 1-2, pp. 105-114, 1994.
29. N.P. Suh, “The delamination theory of wear”, Wear, vol. 25, pp. 111-124, 1973.
30. 趙永慶、陳永楠、張學敏、曾衛東、王磊，鈦合金相變及熱處理，中南大學出版社，2012
31. R. Wanhill and S. Barter, “Fatigue of beta processed and beta heat-treated titanium alloys”, Springer Science & Business Media, 2011.
32. Y.C. Lin and Y.H. Cho, “Elucidating the microstructural and tribological characteristics of NiCrAlCoCu and NiCrAlCoMo multicomponent alloy clad layers synthesized in situ”, Surface and Coatings Technology, vol. 203, no. 12, pp. 1694-1701, 2009.
33. 貴重儀器介紹，available at: http://www.cic.ntust.edu.tw/impo.php
34. “TI950 TriboIndenter User Manual”, Hysitron, 2014.
35. 黃靖媛，超深冷處理程序對於不同鋼材微觀結構與硬度及耐磨耗能力，國立臺灣科技大學碩士學位論文，2016
36. X.H. Wang, S.L. Song, S.Y. Qu and Z.D. Zou, “Characterization of in situ synthesized TiC particle reinforced Fe-based composite coatings produced by multi-pass overlapping GTAW melting process”, Surface and Coatings Technology, vol. 201, no. 12, pp. 5899-5905, 2007.
37. Y. Wu, A.H. Wang, Z. Zhang, R.R. Zheng, H.B. Xia and Y.N. Wang, “Laser alloying of Ti–Si compound coating on Ti–6Al–4V alloy for the improvement of bioactivity”, Applied Surface Science, vol. 305, pp. 16-23, 2014.
38. T.B. Massalski, H. Okamoto, P.R. Subramanian and L. Kacprzak, “Binary Alloy Phase Diagrams”, pp.890, pp.3370, USA, 1990.
39. B. Gaspar, “Microstructural characterization of Ti-6Al-4V and its relationship to sample geometry”, 2012.
40. K.L. Wang, Q.B. Zhang, M.L. Sun and X.G. Wei, “Microstructural characteristics of laser clad coatings with rare earth metal elements”, Journal of materials processing technology, vol. 139, no. 1-3, pp. 448-452, 2003.
41. Y.V. Milman, B.A. Galanov and S.I. Chugunova, “Plasticity characteristic obtained through hardness measurement”, Acta metallurgica et materialia, vol. 41, no. 9, pp. 2523-2532, 1993.
42. S. Zhang, D. Sun, Y. Fu and H. Du, “Toughness measurement of thin films: a critical review”, Surface and Coatings Technology, vol. 198, no. 1-3, pp. 74-84, 2005.
43. J. Guo, H. Wang, F. Meng, X. Liu and F. Huang, “Tuning the H/E* ratio and E* of AlN coatings by copper addition”, Surface and Coatings Technology, vol. 228, pp. 68-75, 2013.