本文探討添加不同比例稀土元素(氧化鑭與氧化釔)，對於中碳鋼表面氬焊被覆二硼化鈦(TiB2)與硼化鎢(WB)兩種陶瓷被覆層之顯微結構與磨耗行為的影響。並找出影響耐磨耗能力之主要關鍵，以做為中碳鋼表面耐磨耗改質的依據。
研究結果顯示，TiB2系列之被覆層均屬於散佈強化型機構。添加氧化鑭(La2O3)、氧化釔(Y2O3)皆具有促使TiB2被覆層強化顆粒之叢聚(clustered)效應，而形成較大尺寸之強化相。並且TiB2系列被覆層之耐磨耗能力則以添加氧化釔(Y2O3)之被覆層效果最佳。原因在於其被覆層中擁有數量較多、尺寸較大之強化相，具較佳之基地固守效應所致。
然而，WB系列之被覆層則屬於析出強化型機構。在WB被覆層中添加氧化鑭(La2O3)、氧化釔(Y2O3)可以使基地的顯微組織微細化，並促進析出物之成長。添加氧化鑭(La2O3)、氧化釔(Y2O3)的WB被覆層內的析出相較厚實，具較佳之機械互鎖效應，其中以添加4.5%氧化釔之WB被覆層效果最佳，使其被覆層之耐磨能力有效地提升。

This thesis studies on the effect of rare earth (La2O3 and Y2O3) on microstructure morphology and wear resistance of clad layer for medium carbon steel cladded with TiB2 and WB powder respectively. Additionally, the major factors that influence wear performance of clad layer were found out in this study.
According to the results of this study, the wear performance of all TiB2 clad layer were improved by the dispersion strengthening. The results also show that adding a little La2O3 and Y2O3 that can promote particles of reinforcement clustered and to connect each other forming a bigger reinforcement. However, the bigger reinforcement has better bonding strength with matrix and can increase significantly the wear resistance ability of TiB2 clad layers.
Nevertheless, WB clad layers were strengthened by the precipitation of reinforcing phases. The results show that adding a little La2O3 and Y2O3 can promote microstructure refining and precipitates growing in WB clad layer. However, the bigger precipitates possess better mechanical interlocking effect and can increase significantly the wear-resistance ability in WB cladding specimens. The wear performance of WB-4.5%Y2O3 clad layer was improved obviously.

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