镀铝锌板表面锌灰成因及控制

镀铝锌彩涂板锌灰的明显现象是在铝锌板表面沿细渣带纵向形成条状或点状夹杂物，属轻微缺陷，但发生频率高于其它渣缺陷。

其形成原因是炉头锌表面的浮渣和炉头内腔凝结的固体锌渣产生锌灰。锌渣落在带钢表面，随着带钢通过锌锅沉辊产生轻微的线性压痕，或细渣带在镀铝锌彩涂板表面沿纵向形成条状或点状夹杂物，造成锌灰缺陷。
镀铝锌彩涂板的形成原因
控制措施如下：
1炉鼻氮气加湿系统的优化
加湿系统可提高露点温度，使锌蒸气在锌液表面形成保护膜，抑制锌液的连续蒸发。如果露点温度控制不当，蒸汽过多可能产生缺陷。因此， 镀铝锌彩涂板在实践中应确定炉鼻的最佳露点温度。
2炉头锌渣的清理
1） 制作专用渣勺，每班清洗炉头浮渣2-3次。
2） 炉鼻内增加了锌渣吸附除渣装置，外部热风通过风机吹入密闭炉鼻。
3） 利用停机时间减少锌锅，露出炉鼻处的锌液位，然后手动除渣。
三。带钢入炉温度控制
严格控制带钢进入锌锅的温度，由于带钢温度超过锌液的20℃，不仅锌锅的温度会升高，而且锌渣的量也会增加。

The apparent phenomenon of zinc ash is the formation of strip or point inclusions along the longitudinal direction of the fine slag belt on the surface of aluminum zinc plate, which is a slight defect, but the frequency of occurrence is higher than other slag defects.

The formation reason is that the zinc ash is produced by the dross on the zinc surface at the furnace nose and the solid zinc slag condensed in the inner cavity of the furnace nose. The zinc slag falls on the surface of the strip steel and produces slight linear indentation along with the strip steel passing through the sink roll of the zinc pot, or the fine slag belt forms strip or point inclusions along the longitudinal direction on the surface of the aluminized zinc plate, resulting in zinc ash defects.
Cause of formation of gray and zinc plated aluminum plate
The control measures are as follows:
1. Optimization of nitrogen humidification system for furnace nose
The humidification system can raise the dew point temperature and make the zinc vapor form a protective film on the surface of liquid zinc to inhibit the continuous evaporation of liquid zinc. If the dew point temperature is not controlled properly, too much steam may produce defects. Therefore, the best dew point temperature of the furnace nose should be determined in practice.
2. Cleaning of zinc slag in furnace nose
1) Make special slag scoop and clean the scum in the furnace nose 2-3 times per shift.
2) The zinc slag adsorption and removal device in the furnace nose is added, and the external hot air is blown into the closed furnace nose through the fan.
3) Use the downtime to reduce the zinc pot, expose the zinc liquid level at the furnace nose, and then remove the slag manually.
3. Temperature control of strip steel entering boiler
Strictly control the temperature of the strip into the zinc pot, because the temperature of the strip exceeds 20 ℃ of the liquid zinc, not only the temperature of the zinc pot will be increased, but also the quantity of zinc slag will be increased.