本文將氮化矽(Si3N4)混合合金粉末(Ti、Nb、Ni、Fe)並添加不同比例稀土元素氧化釹(Nd2O3)預置於低碳鋼基材上，進行氬銲(gas tungsten arc welding；GTAW)被覆，探討被覆層顯微組織、強化相、晶體結構、機械性質、硬度檢測等進行分析。並以銷對圓盤(Pin-on-Disk)方式使用迴轉式磨耗試驗機來進行磨耗試驗，評估被覆層耐磨耗能力。
研究結果顯示，50%Si3N4與添加不同比例(3%、4.5%、6%)氧化釹(Nd2O3)被覆層皆會臨場(in-situ)合成FCC晶體結構的Ti(C,N)顆粒狀析出物與BCC結構葉脈狀Fe3Si強化相。
添加Nd2O3之被覆層可以降低稀釋率，基材稀釋效應減弱，在被覆層內合金元素濃度就高，相對強化相就比較多，促進硬度值15.6Gpa之初晶長條狀強化相Fe16Nb6Si7的析出，並且使葉脈狀強化相Fe3Si減少。其中以44%Si3N4+6%Nd2O3被覆層有最高的平均硬度，約為HV0.3940.9。
磨耗試驗方面，添加稀土元素氧化釹(Nd2O3)被覆層試片能大幅提升耐磨耗能力，其中以45.5%Si3N4+4.5 %Nd2O3被覆層有較佳的耐磨耗能力，因長條狀析出物Fe16Nb6Si7晶粒無太過細小或粗大的現象，使其在磨耗過程中的衝擊效應下不易破碎，而能有效保護摩擦表面。

In this study, Si3N4 ceramic powder and Ti, Nb, Ni, Fe alloy powders mixed with different percentage of Nd2O3 rare element were applied to clad onto AISI 1020 low carbon steel by gas tungsten arc welding(GTAW) process. The microstructure, strengthening phase, crystal structure, mechanical property and hardness examination of clad layers were investigated. In addition, rotating tribometer with the pin-on-disc method was used to conduct the wear test. It was evaluated with wear resistance performance of clad layers.
The experiment results show that FCC crystal structure of Ti(C,N) particle precipitates which synthesized in-situ and BCC crystal structure of Fe3Si vein-like strengthening phase were had in the clad layers which were mixed with 50%Si3N4 and different percentage Nd2O3.
Mixing with Nd2O3 clad layers can reduce dilution rate because substrate dilution effect was reduced. In the clad layer,when alloy element concentration was higher, strengthening phase was relatively increased. It promoted to separate out Fe16Nb6Si7 long precipitates of primary crystal which hardness value was 15.6GPa, and Fe3Si vein-like strengthening phase were reduced. Among of all clad layers,which the 44%Si3N4+6%Nd2O3 was the highest hardness whose value was HV0.3940.9.
The wear test results indicate that clad layers which were mixed with different percentage Nd2O3 were increased the wear resistance, especially for the 45.5%Si3N4+4.5%Nd2O3 clad layer which was had the best wear resistance.Because Fe16Nb6Si7 long precipitates of grains didn’t have more finer or coarsening phenomenon. During wear test of impact effect, long precipitates were not easily broken so that it can protect the friction surface effectively.

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