1 Aluminum specific gravity: pure aluminum 2.71g/cm3; die-cast aluminum alloy 2.6-2.71g/cm3;
The alloy aluminum melting range is 520-600 ° C; the die casting temperature range is 670-710 ° C.
2 How to prevent inhalation?
(1) Water gas: it comes from furnace gas, not fully dried charge, refining agent, covering agent, modifier, un-dried lining, enamel and tool coating, and residue on enamel, tools and charge. Aqueous solvent, these water vapor reacts with aluminum to: 2AL+3H2O→←AL2O3+6H Hydrogen is produced, and hydrogen enters the aluminum liquid in an atomic state.
(2) Oil pollution comes from the charge and tools with grease, and the oil reacts with aluminum to form hydrogen.
(3) The charge contains water-containing corrosives. Reduce the absorption of gas by the aluminum alloy liquid, and the alloy raw materials should be properly stored to prevent moisture. It should be fully preheated and dried before use; the smelting crucible and tools should be fully preheated to remove water vapor before use. In order to remove the gas from the aluminum alloy liquid, all aluminum alloy liquids must be degassed before pouring.
3 Nitrogen refining method (also known as inert gas degassing method)
Basic principle: nitrogen is introduced into the bottom of the aluminum liquid through a certain process device, and when nitrogen floats upward from the bottom of the aluminum liquid in the form of bubbles, there is a difference in partial pressure of hydrogen at the interface between the bubble and the aluminum liquid, and the inside of the bubble The partial pressure of hydrogen is very low. During the process of hydrogen partial pressure tending to balance, the hydrogen in the alloy liquid continuously enters the bubble. When the bubble rises to the liquid surface, the hydrogen then escapes into the atmosphere, and the bubble rises. During the process, the oxidized slag and its fixed impurities are simultaneously adsorbed and floated together to the liquid surface. The inert gas should be condensed and dehydrated before use to prevent moisture from entering the aluminum liquid. The quality of refining is good and the pores are inevitably small.