【摘要】：鎂合金重量輕、比強度高,在航天、軍工和電子行業(yè)的應用受到廣泛關注,如何獲得耐蝕、耐磨性高的鎂合金是鎂合金的研究熱點。本文通過向鎂合金活化液中添加微量Cu2+來改善鎂合金電沉積預處理工藝,進而采用脈沖電沉積的方法在鎂合金表面制備Ni-SiC復合鍍層,對脈沖電沉積工藝參數(shù)進行優(yōu)化,并研究了Ni-SiC復合鍍層的硬度、耐蝕性和耐磨性。以化學鍍Ni作為鎂合金的電沉積預處理,隨后,將化學鍍鎳后的鎂合金置于酸性瓦特鍍液中進行直流電沉積Ni,獲得的Ni鍍層表面粗糙度較大,鍍層與基體結(jié)合力差,出現(xiàn)局部開裂,且鍍層表面出現(xiàn)一些龜裂紋。其次,采用堿式預鍍銅作為鎂合金電沉積預處理工藝,并優(yōu)化了在鎂合金表面堿式預鍍Cu的工藝,將預鍍Cu后的鎂合金在酸性瓦特鍍液中進行直流電沉積,得到了結(jié)構(gòu)完整的Ni鍍層,說明堿式預鍍Cu處理對鎂合金起到了有效的保護作用。采用脈沖電沉積在鎂合金表面制備Ni-SiC復合鍍層,對復合鍍層的微觀形貌、成分和性能進行分析,所獲得Ni-SiC復合鍍層表面結(jié)構(gòu)完整,SiC顆粒均勻地分布于Ni基質(zhì)鍍層中;隨著復合鍍液中SiC添加量的增加,復合鍍層中的SiC含量升高,鍍層的硬度、耐蝕性、耐磨性均呈現(xiàn)先提高后下降的趨勢,當鍍液中SiC的添加量為40 g/L時,復合鍍層的耐蝕性、耐磨性達到最佳。以脈沖電流的占空比為單因素變量,探究了脈沖電流占空比對鎂合金表面脈沖電沉積Ni-SiC復合鍍層的微觀形貌、成分及性能的影響,研究表明,當脈沖占空比為50%時,所制備的Ni-SiC復合鍍層SiC含量最高,鍍層的硬度、耐蝕、耐磨性均達到最佳。
[Abstract]:Magnesium alloys are light in weight and high in specific strength. The applications of magnesium alloys in aerospace, military and electronic industries have been widely concerned. How to obtain corrosion resistant magnesium alloys with high wear resistance is a hot research topic of magnesium alloys. In this paper, the pretreatment process of magnesium alloy electrodeposition was improved by adding trace Cu2 to magnesium alloy activation solution, and then Ni-SiC composite coating was prepared on magnesium alloy surface by pulse electrodeposition, and the parameters of pulse electrodeposition were optimized. The hardness, corrosion resistance and wear resistance of Ni-SiC composite coating were also studied. The electroless Ni was used as the electrodeposition pretreatment of magnesium alloy, and then the electroless nickel plated magnesium alloy was placed in acid watt bath for direct current electrodeposition (Ni,). The surface roughness of the Ni coating was larger, and the adhesion between the coating and the substrate was poor. There are local cracks and some tortoise cracks on the coating surface. Secondly, the basic pre-copper plating was used as the pretreatment process of magnesium alloy electrodeposition, and the process of basic pre-plating of Cu on magnesium alloy surface was optimized. The magnesium alloy after pre-plating Cu was deposited in acid Watt bath. The Ni coating with complete structure was obtained, which shows that the basic preplating Cu treatment has an effective protective effect on magnesium alloy. The Ni-SiC composite coating was prepared on magnesium alloy surface by pulse electrodeposition. The microstructure, composition and properties of the composite coating were analyzed. The surface structure of the Ni-SiC composite coating was complete and the SiC particles were uniformly distributed in the Ni matrix coating. With the increase of SiC content in the composite plating bath, the content of SiC in the composite coating increased, and the hardness, corrosion resistance and wear resistance of the coating increased first and then decreased. When the addition of SiC in the bath was 40 g / L, The corrosion resistance and wear resistance of the composite coating are the best. With the duty cycle of pulse current as a single factor variable, the effects of pulse current duty ratio on the microstructure, composition and properties of pulsed electrodeposition Ni-SiC composite coating on magnesium alloy surface were investigated. The results showed that when the pulse duty ratio was 50, the effect of pulse duty ratio on the microstructure, composition and properties of Ni-SiC composite coating was investigated. The Ni-SiC composite coating has the highest SiC content and the best hardness, corrosion resistance and wear resistance.
【學位授予單位】：西安科技大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TG174.4

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