Method for preventing oxidizing fire of magnesium alloy

A magnesium alloy and mixed gas technology, applied in the field of magnesium alloy metallurgy, can solve problems such as environmental equipment and human body hazards, and achieve the effect of preventing oxidative combustion and good protection effect

Inactive Publication Date: 2008-07-16
TSINGHUA UNIV +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] In order to solve the current international magnesium industry using SF with high greenhouse effect 6 and toxic SO 2 The environment, equipment, and human hazards caused by the gas for magnesium alloy smelting and protection, the invention provides a method for preventing high-temperature oxidation and combustion of magnesium alloys by using low-greenhouse effect, non-toxic trifluoroiodomethane gas

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0014] Magnesium alloy AZ91D is smelted in a non-sealed resistance crucible furnace with a volume of 25 liters and a melting temperature of 700°C, using 0.3% iodotrifluoromethane (molecular formula CF 3 I) and 99.7% N 2 The mixed gas, the flow rate of the mixed gas is 0.9L per minute, and the magnesium alloy smelting gas protection is carried out.

[0015] Put the dried charge (3 kg) into the crucible of the resistance crucible furnace, and cover the crucible lid. Turn on the melting furnace, heat the crucible, the heating rate is 10°C / min, and feed a mixed gas at 200°C, the mixed gas composition is 0.3% trifluoroiodomethane and 99.7% N 2 , the flow rate of the mixed gas is 0.9L / min. After heating up to melting, the protective gas quickly forms a dense and well-protective protective film on the surface of the magnesium melt. After melting, continue to heat up to 700°C and keep it warm for 1 hour. , and then cast. During the whole smelting and heat preservation process, the ...

Embodiment 2

[0017] Magnesium alloy AM50 was smelted in an unsealed resistance crucible furnace with a volume of 25 liters and a melting temperature of 700°C using 0.2% trifluoroiodomethane and 99.8% N 2 The mixed gas, the flow rate of the mixed gas is 1.0L per minute, and the magnesium alloy smelting gas protection is carried out.

[0018] Put the dried charge (3 kg) into the crucible of the resistance crucible furnace, and cover the crucible lid. Turn on the melting furnace, heat the crucible, the heating rate is 10°C / min, and feed a mixed gas at 200°C, the mixed gas composition is 0.2% trifluoroiodomethane and 99.8% N 2 , the flow rate of the mixed gas is 1.0L / min. After heating up to melting, the protective gas quickly forms a dense and well-protective protective film on the surface of the magnesium melt. After melting, continue to heat up to 700°C and keep it warm for 1 hour , and then cast. During the whole smelting and heat preservation process, the mixed gas containing iodotriflu...

Embodiment 3

[0020] Magnesium alloy AZ91D was melted in a sealed melting furnace with a volume of 30 liters and a melting temperature of 700°C using 0.1% trifluoroiodomethane and 99.9% N 2 The mixed gas for protection.

[0021] The dried magnesium alloy charge (5 kg) is put into the crucible in the sealed smelting furnace, and then the sealed smelting furnace cover is covered. Open the vacuum system, remove the air in the melting furnace, and turn off the vacuum pump when the pressure in the melting furnace is 1Pa. Fill the sealed melting furnace with 0.1% trifluoroiodomethane and 99.9% N 2 mixed gas, when the furnace pressure is 1×10 5 At Pa, close the inflation port. Turn on the power supply of the heating furnace, start to smelt the magnesium alloy, the smelting temperature is 700°C, and keep warm for 1 hour. During the whole magnesium alloy smelting process, no oxidative combustion phenomenon occurred.

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Abstract

The invention relates to a method for preventing the oxidation and burning of magnesium alloy and belongs to the field of metallurgy technology of magnesium alloy. The method comprises the following steps: the melting protection of the magnesium alloy is made by pumping the mixed gas of trifluoroiodomethane gas and dilute gas into a melting furnace of magnesium alloy; when the magnesium alloy is melted, the gas is dried, mixed and transported to a magnesium alloy surface which is needed to be protected with conventional methods; wherein, the purity of the trifluoroiodomethane and the dilute gas in the mixed gas is the industrial purity, and the dilute gas is one or a plurality of the gases of dry N2, CO2, Ar and compressed air; mixed gas of different proportions and ventilation modes are adopted according to the sealing conditions of the melting furnace of the magnesium alloy; the mixed gas comprising the trifluoroiodomathane is adopted for the melting protection when the magnesium alloy is melted in unsealed melting furnaces or sealed melting furnaces, which has good protecting effect and the advantage of environment-friendliness compared with the protection of sulfur hexafluoride, and the invention is simple in technique of melting protection and has good industrial application prospect.

Description

technical field [0001] The present invention relates to a kind of method that prevents the oxidative combustion when smelting of magnesium alloy, adopt trifluoroiodomethane (molecular formula CF 3 1) The mixed gas with diluent gas is used as protective gas during magnesium alloy smelting, and belongs to the technical field of magnesium alloy metallurgy. Background technique [0002] Magnesium alloy not only has low density, high specific strength and high specific stiffness, but also has the advantages of good damping performance, good cutting performance, good electrical conductivity, stable size, low cost, no pollution, and easy recycling. It has been widely used in fields such as aviation and aerospace, and is one of the important lightweight and high-strength materials in the 21st century. However, some key technologies that hinder the large-scale application of magnesium alloys have not been resolved, such as magnesium alloys are prone to oxidative combustion during sm...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C1/02C22C23/00
Inventor 熊守美陈晓
Owner TSINGHUA UNIV
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