Tribocorrosion properties of nickel aluminum bronze coating prepared by cold spraying in different pH environment
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摘要: 鎳鋁青銅合金是鑄造大型艦艇螺旋槳的主要材料,海洋污損生物在合金表面附著引起的pH值變化會加速鎳鋁青銅合金的腐蝕磨損,威脅到艦艇安全航行.采用冷噴涂技術制備了較為致密的鎳鋁青銅涂層,厚度約300 μm,利用掃描電鏡、光學顯微鏡觀察了涂層的微觀形貌,重點研究了涂層在pH值分別為3、7和11,質量分數為3.5%的NaCl溶液中的電化學腐蝕性能和腐蝕磨損行為.實驗結果表明:pH值為3的環境中,鎳鋁青銅基體發生了選相腐蝕,表面疲勞裂紋主要分布在富Cu的α相上,涂層上的犁削溝槽加深發生了磨粒磨損,涂層耐腐蝕性能優于基體;pH值為7的環境中,基體發生了黏著磨損,表面有片層狀金屬剝落,涂層中的孔隙收容了大量磨屑避免了劇烈的三體摩擦,表面犁削溝槽較淺,涂層致鈍電位高于基體,耐腐蝕性能變差.pH值為11的環境中,基體發生了表面疲勞磨損,涂層磨痕上有較深的犁削溝槽,溝槽內有微裂紋,涂層耐腐蝕性能優于基體.總體來說,在不同pH值環境中,涂層由于在冷噴涂過程中發生了冷加工硬化并且涂層上的孔隙收容了磨屑,導致涂層的耐腐蝕磨損性能增強.Abstract: Nickel aluminum bronze is the main material used to cast large ship propellers. However, marine biofouling on the surface of the propeller alters the pH value, thereby accelerating tribocorrosion and threatening ship safety. In this study, a compact nickel aluminum bronze coating with a thickness of approximately 300 μm was deposited by cold spraying. The microstructure of the coating was observed by scanning electron microscopy and optical microscopy. The electrochemical corrosion properties and tribocorrosion behavior of the coating was determined using 3.5% NaCl solution in different pH environments of 3, 7, and 11. Results show that in a pH 3 environment, optional corrosion occurs on the nickel aluminum bronze substrate, cracks mainly containing Cu are mostly distributed on α phases, deep cannelure is observed on the wear trace of the coating, and abrasive wear occurs on the coating. In a pH 7 environment, adhesive wear occurs on the substrate, slice abrasive dust is distributed on the surface of wear trace of the substrate (because porosities on the coating absorb most of the abrasive dust and avoid three body friction), cannelure on the coating is relative shallow. In pH 11 environment, surface fatigue occurs on the surface of the substrate and deep cannelure is observed on the wear trace of coating, which contains cracks. Generally speaking, tribocorrosion resistance of coating enhances during cold spray process in different pH environments, resulting from cold working hardening and abrasive dust entering the coating pores.
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Key words:
- nickel aluminum bronze /
- cold spray /
- pH value /
- tribocorrosion
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參考文獻
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