Study Of The Property Of The Dross In GL Pool And The Effect Of Different Elements On The Dross

It could have scientific and practical significance in reducing the bottom dross in GL pool by scientific research.We have studied the effect of cleaning methods and adding elements of Ti and V on the microstructure and phase composition of bottom dross by the micro vickers hardness tester?OM?SEM and EDS.The main conclusions are as follows:Except for aluminum zinc plating solution and aluminium-rich phase,there are two dfferent microstructure of the bottom dross in the GL pool by different bottom dross cleaning methods.One kind of the microstructure consist of FeAl₃ intermetallic compound or Al₈Fe₂Si,and the other one consist of Al₃V.It shows that there are two types of vickers hardness by micro-vickers sclerometer analysis.It does no obvious benefit to reducing the hardress of the bottom dross by different cleaning methods.Before adding Ti alloy ingot,the bottom dross microstructure of Al-Zn liquid solidification is obtained in the position 100 mm and 400 mm off the liquid level,which consist of Al₈Fe₂Si intermetallic compounds.After adding Ti alloy ingot,there two different kinds of the bottom dross microstructure of Al-Zn liquid solidification.One consist of Al₈Fe₂Si intermetallic compound,and the other consist of Al₃V intermetallic compound.It becomes biger and biger with the hot dip process.It produces a large amount of bottom dross in the alloy liquid after 3.0 wt.%Fe being added in the 55%Al-Zn-Si alloy liquid.Therefore Fe is the main element for the formation of bottom dross.The Fe-Al binary phase diagram shows that the microstructure is FeAl₃ intermetallic compound.The size of bottom dross become biger and biger with the increase of Ti after different content of Ti?0.02 wt.%,0.05 wt.%,0.10 wt.%,0.20wt.%?being added to the 55%Al-Zn-Si alloy liquid.When the content of Ti is 0.20 wt.%,TiAl₃ intermetallic compounds was precipitated from the plating solution.It has a high hardness and melting point for TiAl₃.Therefore the content of Ti for decreasing the size of spangle should be controlled under 0.10 wt.%.The size of the precipitation organization become biger and biger with the increase of the content of V after different content of V?0.02 wt.%,0.05 wt.%,0.10 wt.%,0.20 wt.%?being added into the 55%Al-Zn-Si alloy liquid.The size ranges from 80 to 180?m,and the quantity becomes more and more.When the content of V is 0.20 wt.%,the bottom dross consist of three kinds of microstructure.One kind of microstructure consist of FeAl₃intermetallic compound,another one consist of Al₄₅V₇ intermetallic compound,and the other consist of Al₂₁V₂ intermetallic compound.The impurities containing V should be removed on account of it would promote the formation of the bottom dross.