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利用OM、SEM、EDS、XRD等研究55%Al-43.4%Zn-1.6%Si合金镀层表面锌花特征、合金元素分布规律;通过极化曲线研究镀层不同区域耐腐蚀行为,并探讨热浸镀形成过程及在腐蚀过程中组织演变规律。结果表明:不同尺寸特征的锌花其金相组织均是由垂直网格状树枝晶构成,且晶臂间距大小一致;不同尺寸锌花表面成分均是由Al、Zn组成,且含微量Si元素,Al、Zn元素约为2∶1;大小尺寸锌花的金属化合物层中α-{Fe,Al,Si}相数量不同是造成锌花尺寸不均的主要原因,锌花尺寸数值越小,IMC层中τ5相数量越多,凝固过程中形核点就会越多,形成的锌花尺寸就越细小;采用多点采集统计,不同尺寸特征的锌花其耐蚀性几乎相当。
The characteristics of the bloom and the alloying elements on 55% Al-43.4% Zn-1.6% Si alloy coating were investigated by OM, SEM, EDS and XRD. The polarization curves were used to study the corrosion resistance of the coating in different regions. Formation process and evolution of the organization during the corrosion process. The results showed that the microstructure of Zinc flower with different size was composed of vertical grid dendrite with the same crystal arm spacing. The surface compositions of Zinc flower with different sizes were composed of Al and Zn with trace Si , Al, Zn element is about 2: 1; the number of a- {Fe, Al, Si} phase in the metal compound layer of the size-sized zinc flower is the main reason for the uneven size of the zinc flower, In the IMC layer, the more the number of τ5 phases, the more nucleation sites will be formed during the solidification and the smaller the size of the formed zinc flower. Using the multi-point collection statistics, the corrosion resistance of the zinc flower with different size features is almost equal.