CN102140617A - Method for sulfurizing iron lift tube for low pressure casting - Google Patents

Abstract

The invention discloses a method for sulfurizing iron lift tube for low pressure casting of aluminum and magnesium alloys, which comprises the following steps of: thoroughly removing surface dirt and rust of the lift tube by using a sand blasting method, coating slurry consisting of 70 percent of sulphur powder, 25 percent of boric acid and 5 percent of water glass on the treated surface, wrapping an aluminum foil, putting into an oven with the temperature of between 500 and 550 DEG C, keeping the temperature for 8 to 10 hours, and ensuring that sulphur in the slurry is reacted with iron to form FeS which is not infiltrated with aluminum so as to prevent the aluminum from reacting with the lift tube to protect the lift tube.

Description

Low-pressure casting irony riser pipe vulcanization process

Technical field

What the present invention relates to is a kind of aluminium, magnesium alloy low-pressure casting irony riser pipe sulfurized method of being used for, and belongs to the liquid condition shaping and the field of surface treatment of metallic substance.

Background technology

Riser pipe is a critical part in the low-pressure die casting plant, usually cylinder iron or weldless steel tube and steel plate be welded, because it directly is immersed in the aluminium liquid, be subjected to the etch of high temperature aluminum liquid and wash away, iron and reactive aluminum make the very fast damage of riser pipe, and iron ion directly enters the FeAl3 that aluminium liquid and aluminium generate strip simultaneously, become the most deleterious tissue in the aluminium casting, it isolates matrix, worsens mechanical property, and its tensile strength and elongation sharply descend.

Enterprise takes to brush CaCO3 in producing usually at present, talcum powder stops the iron in the riser pipe directly to contact with aluminium; but aluminium liquid washes away inside and outside riser pipe down repeatedly when long term high temperature (720～750 ℃) and low-pressure casting; this coating is very easy peels off, and does not have provide protection.

Summary of the invention

Studies show that; iron crucible, instrument and riser pipe surface and form certain thickness FeS layer; because FeS and aluminium do not soak into; stopped the etch of aluminium to iron, both protected iron crucible and riser pipe also to avoid the iron that increases of alloy, once the someone attempted adding sulphur iron ore in crucible in the past; in the crucible temperature-rise period; sulphur in the sulfurous iron ore discharges with crucible and generates FeS, facts have proved that this method affect factor is too many, and cure efficiency is not good.

Purpose of the present invention is at the deficiency of sulfurous iron ore method and seek a kind of material and sulfuration process of new sulfidizing.

Technical scheme of the present invention is as follows:

The prescription of irony riser pipe vulcanizing agent is: 70% SULPHUR POWDER, 25% boric acid, 5% water glass water is an amount of.

Vulcanizing agent configuration technology is: SULPHUR POWDER and boric acid are fully mixed, and water glass dissolves in the hot water, then SULPHUR POWDER and boric acid miscellany are added, and it is stand-by to stir.

Irony riser pipe sulfidizing technology: riser pipe is embroidered with the thorough de-iron dirt of method and the iron of sandblast or ball blast, blows clean with pressurized air, and vulcanizing agent is sprayed on surfaces externally and internally, dry in the shade, and then spray one deck, and repeatable operation 2～3 times, coat-thickness reaches 1.5～3.0mm, after drying in the shade, outside surface is tight with 0.5mm aluminium foil parcel, puts into baking oven, and oven temperature is controlled between 500～550 ℃, heated 8～10 hours, and made it generate certain thickness FeS layer.

Embodiment

Riser pipe bore (external diameter) 110mm, wall thickness 5mm, the steel plate of A3 seamless tube and thickness 10mm is welded, and length is 1200mm.Riser pipe has just pressed sand blasting sand to handle with 20～40 purposes palm fibre, thoroughly removes iron and embroiders, and blows clean with clean pressurized air then, riser pipe is placed on is heated to 120～150 ℃ in the box-type furnace.Measured SULPHUR POWDER of scale and boric acid is fully mixed, and water glass dissolves in the hot water, then adds the miscellany of sulphur semi-annular jade pendant powder and boric acid, makes it to become the vulcanizing agent slurry.In box-type furnace, take out riser pipe, spray and spray the second layer again after the first layer vulcanizing agent (slurry) waits its drying, the baking oven of putting into 15 () ℃ makes its drying, and then sprays the 3rd layer, wrap up with the 0.5mm aluminium foil dry back, and two ends of riser pipe are also tight with Aluminium Foil Package.Put into baking oven, be warmed up to 520 ℃, be incubated 8 hours, the vulcanizing agent residue is removed with brush in the cooling back, and is stand-by.This riser pipe uses 120 heats continuously.After testing, this sulfurized layer reaches 0.35mm, illustrates that this method is effective, and is easy to use.

Claims (2)

1. a low-pressure casting is characterized in that its composition is a SULPHUR POWDER 70%, boric acid 25%, water glass 5% and an amount of water with irony riser pipe vulcanizing material.

2. a low-pressure casting is with irony riser pipe sulfuration process; it is characterized in that removing the dirt activating surface with the method for sandblast or ball blast; brush irony riser pipe sulfuration oar material then; the outside wraps foil sealing; Heating temperature to 500～550 ℃ also kept 8～10 hours, made the riser pipe surface reaction generate the FeS protective layer.