本研究以電鍍技術在Inconel 718合金表面,經過不同溫度及時間熱氧化處理後,再電鍍沉積鎳磷塗層,分析不同塗層結構和硬度值,以及耐腐蝕性和耐磨耗腐蝕性。 實驗中使用Inconel 718合金經過不同溫度(600˚C、700˚C、950˚C)及不同時間(1h、24h、48h、72h)熱氧化處理後,進行電鍍鎳磷塗層,以維克氏硬度量測儀測得塗層之硬度,以燒結氧化鋁(Al2O3)陶瓷環使用塊對環(Block-on-ring)表面磨耗方式,分析耐磨耗腐蝕性,以及使用電化學腐蝕實驗,分析耐腐蝕性,最後用掃描式電子顯微鏡(SEM)和能量散射光譜儀(EDS),分析塗層在腐蝕和磨耗腐蝕前後的表面形態和元素成分。 實驗結果顯示Inconel 718合金,經過不同溫度及不同時間熱氧化處理後再電鍍鎳磷塗層,會有較高的硬度值,較優越的耐磨耗腐蝕性,但也降低了合金鈍態腐蝕保護性而基材經過熱氧化處理後,會提升氧化及鎳磷塗層的緻密性與沉積效率,因此對於表面硬度、耐腐蝕性與耐磨耗腐蝕性,有更好的提升效果。
The purpose of the present study is to evaluate the structure and mechanical properties of the electroplated Ni-P/Oxide composite coatings as well as their effect on the corrosion and wear-corrosion resistance of Inconel 718 alloy in 3.5 wt.% NaCl solution. The thermal oxidation process was performed on Inconel 718 surface with different temperature (600˚C、700˚C、950˚C) and holding time (1h、24h、48h、72h) to enhance the adhesive strength of these composite coatings on Inconel 718 alloy. The surface morphologies and element compositions of the composite coatings before and after all tests are analyzed by scanning electron microscopy (SEM) and X-ray energy dispersive analyzer (EDS). The surface hardness of the specimens was measured by a Vickers′ hardness tester. Electrochemical polarization measurements are performed for analyzing corrosion characteristics, and using the block-on-ring surface friction manner to evaluate the wear-corrosion behavior of these composite coatings in Hanks′ solution. The friction ring counterpart is made of a sintered Al2O3. Experimental results indicated that the anodizing and thermal oxidation treatment could enhance the electroplated Ni-P coating in addition to the electroplated Ni-P/oxide composite coatings. The hardness and wear–corrosion resistance of the electroplated Ni-P/oxide composite coating were improved significantly for Inconel 718 alloy. The thermal oxide treatment during high temperature of 950˚C also enhance the hardness, corrosion and wear-corrosion behavior of Inconel 718 alloy, and were increased with increasing holding time.