CN105014049A - Al2O3-contained paint for aluminum alloy infiltration casting and method for preparing infiltration casting coating through Al2O3-contained paint - Google Patents

Abstract

The invention provides a Al2O3-contained paint for aluminum alloy infiltration casting and a method for preparing a infiltration casting coating through the Al2O3-contained paint. The paint mainly comprises, by weight, 25 parts to 45 parts of Al2O3, 40 parts to 60 parts of CrO3, 3 parts to 10 parts of fused salt, 3 parts to 6 parts of sodium fluoride and 1 part to 3 parts of a binding agent. Compared with the prior art, the Al2O3-contained paint for aluminum alloy infiltration casting and the method for preparing the infiltration casting coating through the Al2O3-contained paint have the beneficial effects that the number of preparing working procedures is fewer, the preparing cycle is short, and the production cost is low; most importantly, as the specific paint is combined with the infiltration casting technology, the corrosion resistance of the prepared coating suitable for an aluminum alloy is greatly improved; and meanwhile, the thickness of the obtained coating ranges from several micrometers to more than ten micrometers, and therefore influences on the heat conductivity of the aluminum alloy are reduced to the maximum degree.

Description

A kind of aluminum alloy cast containing alundum (Al2O3) oozes with coating and utilizes it to prepare the method for casting impregnation coating

Technical field

The present invention relates to a kind of aluminum alloy cast containing alundum (Al2O3) ooze with coating and utilize it to prepare the method for casting impregnation coating, effectively can improve the decay resistance of Cast aluminium alloy gold surface, belong to casting technology field.

Background technology

Aluminium is the active metal of a kind of chemical property, is just easy at normal temperatures react with oxygen, generates the aluminum oxide film that one deck is fine and close and firm. this layer film can stop the aluminium of internal layer to be oxidized further, can meet requirement used in everyday.But under weak acid, alkali condition, the limited use of this tunic, effectively can not stop the corrosion of aluminium alloy, thus, has higher requirement to the decay resistance of aluminium alloy.

As the application of cast aluminium in condensing type water heater.Set up condensing heat exchanger at gas heater afterbody, can reduce exhaust gas temperature, by the water vapor condensation in flue gas while release obvious heat of smoke, make it to discharge latent heat of liquefaction, therefore comparatively conventional hot water's device is high by 10% ~ 15% for its thermal efficiency.Usually its exhaust gas temperature is lower than 110 DEG C, and the thermal efficiency is not less than 96%.Another benefit adopting condensed type combustion gas water heater is that condensed water can by SO in flue gas _xand NO _xdissolve Deng sour gas, effectively can reduce the pollution that fume emission causes, alleviate environmental pollution.

The heat conductivility of cast aluminium is excellent, and thermal conductivity is apparently higher than cast iron, and aluminium is cheap in addition, is applicable to industrial extensive use.Secondly, from design, the Reliable Design of cast aluminium heat exchanger also makes it have sufficient advantage: the wall thickness of aluminium heat-exchange device is large, on the basis ensureing higher heat transfer intensity, can bear higher hydraulic pressure, remains steady in a long-term and runs; And there is good mobility, casting and excellent processability after aluminum alloy melting.Based on these features, cast aluminium condensing heat exchanger is developed rapidly in recent years.

But define because acidic materials are dissolved in condensed water the acidic liquid that pH value is about 3 ~ 5, the aluminium alloy of meeting heat exchanger condensation segment produces serious corrosion, reduces the service life of water heater, the security that impact uses.

Casting is oozed and is also Cast-in-place hardfacing, that the various alloy powders that will form surperficial particularity ergosphere adhere to, paste solid or brush in the particular surface of casting mold, then liquid metals is poured into a mould, utilize its heat that coating material is melted and with base metals physical bond or reaction bonded, thus formed at cast(ing) surface there is the technology of the coating of property.As compared to existing anodic oxidation, plating, chemical plating, laser melting coating, differential arc oxidation and plasma spraying etc., aluminium alloy surface treatment method, casting is oozed and is not needed special equipment, not by the restriction of cast shape, can process arbitrary surface of foundry goods, conventional cast and material surface compound technology combine by it, while casting, carry out surface treatment, and the latent heat taken full advantage of when the waste heat of molten metal and molten metal solidify, without the need to following process, operation is simple, and energy consumption reduces.

At present, the research of existing Infiltration technology, mainly around ferrous metal, also has the research of Mg alloy castings technology of infiltration casting in recent years, and does not also have Infiltration technology to be applied to the research of aluminium alloy at present.

Summary of the invention

Goal of the invention: in order to overcome the deficiencies in the prior art, the invention provides a kind of containing alundum (Al2O3) (hereinafter referred Al ₂o ₃) aluminum alloy cast ooze with coating and utilize its prepare casting impregnation coating method.

Technical scheme: for achieving the above object, the invention provides a kind of containing Al ₂o ₃aluminum alloy cast ooze with coating, its primarily of following weight ratio component made by:

25 ~ 45 parts of Al ₂o ₃, 40 ~ 60 parts of CrO ₃, 3 ~ 10 parts of fused salts, 3 ~ 6 parts of sodium fluorides, 1 ~ 3 part of binding agent.

As preferably, described containing Al ₂o ₃aluminum alloy cast ooze with coating primarily of following weight ratio component made by:

30 ~ 40 parts of Al ₂o ₃, 45 ~ 55 parts of CrO ₃, 5 ~ 8 parts of fused salts, 3 ~ 6 parts of sodium fluorides, 1 ~ 3 part of binding agent.

Preferred as another kind, described contains Al ₂o ₃aluminum alloy cast ooze with coating primarily of following weight ratio component made by:

35 parts of Al ₂o ₃, 52 parts of CrO ₃, 7 parts of fused salts, 4 parts of sodium fluorides, 2 parts of binding agents.

Preferred as another kind, described Al ₂o ₃particle size>=250 order.

Preferred as another kind, described fused salt is by NaCl, KCl and MgCl ₂by mole than being 18:47:35 composition.

Preferred as another kind, described binding agent sodium carboxymethylcellulose or polyvinyl alcohol.

Present invention also offers described in utilizing containing Al ₂o ₃aluminum alloy cast ooze with coating prepare casting impregnation coating method, comprise the following steps:

(1) Al is got ₂o ₃, CrO ₃, fused salt, sodium fluoride and binding agent mix, add pure water and make coating;

(2) above-mentioned coating is coated in casting mold die cavity or core surface, dries under temperature is 100 ~ 120 DEG C of conditions;

(3) melted aluminium liquid is poured into above-mentioned die cavity or core surface, the coating on aluminium liquid and die cavity or core surface interacts, and namely obtains described coating at cast(ing) surface.

As preferably, described casting mold is waterglass sand mold, resin bonded sand mould or core.

Preferred as another kind, described pouring temperature is 720 ~ 750 DEG C.

Beneficial effect: relative to prior art, aluminum alloy cast of the present invention oozes with coating and utilizes it to prepare the method for casting impregnation coating, not only there is manufacturing process few, manufacturing cycle is short, the advantage of the advantages such as production cost is low, the most important thing is by specific coating, in conjunction with Infiltration technology, made by be applicable to the coating of aluminium alloy, its corrosion resistance improves greatly; Meanwhile, the thickness of gained coating, between several microns to more than ten microns, at utmost reduces the impact on aluminium alloy thermal conductivity.

Detailed description of the invention

Below in conjunction with embodiment, the present invention is further described.

Embodiment 1

Component and proportioning:

25 parts of Al ₂o ₃, 60 parts of CrO ₃, 10 parts of fused salts, 6 parts of sodium fluorides, 3 parts of sodium carboxymethylcelluloses;

Described Al ₂o ₃particle size>=250 order;

Described fused salt is by NaCl, KCl and MgCl ₂by mole than being 18:47:35 composition.

Preparation method:

(1) Al is got ₂o ₃, CrO ₃, fused salt, sodium fluoride and sodium carboxymethylcellulose mix, add pure water and make coating;

(2) above-mentioned coating is coated in waterglass sand mold die cavity, dries under temperature is 100 DEG C of conditions;

(3) melted aluminium liquid is poured into above-mentioned die cavity, pouring temperature is 730 DEG C, and the coating of aluminium liquid and mold cavity surface interacts, and namely obtains described coating at cast(ing) surface.

Embodiment 2

Component and proportioning:

45 parts of Al ₂o ₃, 40 parts of CrO ₃, 3 parts of fused salts, 3 parts of sodium fluorides, 1 part of polyvinyl alcohol;

Described Al ₂o ₃particle size>=250 order;

Described fused salt is by NaCl, KCl and MgCl ₂by mole than being 18:47:35 composition.

Preparation method:

(1) Al is got ₂o ₃, CrO ₃, fused salt, sodium fluoride and polyvinyl alcohol mixing evenly, add pure water and make coating;

(2) above-mentioned coating is coated in resin bonded sand mould die cavity, dries under temperature is 120 DEG C of conditions;

(3) melted aluminium liquid is poured into above-mentioned die cavity, pouring temperature is 720 DEG C, and the coating of aluminium liquid and mold cavity surface interacts, and namely obtains described coating at cast(ing) surface.

Embodiment 3

Component and proportioning:

41 parts of Al ₂o ₃, 40 parts of CrO ₃, 10 parts of fused salts, 6 parts of sodium fluorides, 3 parts of sodium carboxymethylcelluloses;

Described Al ₂o ₃particle size>=250 order;

Described fused salt is by NaCl, KCl and MgCl ₂by mole than being 18:47:35 composition.

Preparation method:

(1) Al is got ₂o ₃, CrO ₃, fused salt, sodium fluoride and sodium carboxymethylcellulose mix, add pure water and make coating;

(2) above-mentioned coating is coated in core surface, dries under temperature is 110 DEG C of conditions;

(3) melted aluminium liquid is poured into above-mentioned die cavity, pouring temperature is 730 DEG C, and the coating on aluminium liquid and core surface interacts, and namely obtains described coating at cast(ing) surface.

Embodiment 4

Component and weight ratio:

35 parts of Al ₂o ₃, 52 parts of CrO ₃, 7 parts of fused salts, 4 parts of sodium fluorides, 2 parts of sodium carboxymethylcelluloses;

Described Al ₂o ₃particle size>=250 order;

Described fused salt is by NaCl, KCl and MgCl ₂by mole than being 18:47:35 composition.

Preparation method:

(1) Al is got ₂o ₃, CrO ₃, fused salt, sodium fluoride and sodium carboxymethylcellulose mix, add pure water and make coating;

(2) above-mentioned coating is coated in core surface, dries under temperature is 110 DEG C of conditions;

(3) melted aluminium liquid is poured into above-mentioned die cavity, pouring temperature is 750 DEG C, and the coating on aluminium liquid and core surface interacts, and namely obtains described coating at cast(ing) surface.

Embodiment 5

Component and proportioning:

30 parts of Al ₂o ₃, 60 parts of CrO ₃, 4 parts of fused salts, 4 parts of sodium fluorides, 2 parts of polyvinyl alcohol;

Described Al ₂o ₃particle size>=250 order;

Described fused salt is by NaCl, KCl and MgCl ₂by mole than being 18:47:35 composition.

Preparation method:

(1) Al is got ₂o ₃, CrO ₃, fused salt, sodium fluoride and polyvinyl alcohol mixing evenly, add pure water and make coating;

(2) above-mentioned coating is coated in waterglass sand mold die cavity, dries under temperature is 120 DEG C of conditions;

(3) melted aluminium liquid is poured into above-mentioned die cavity, pouring temperature is 740 DEG C, and the coating of aluminium liquid and mold cavity surface interacts, and namely obtains described coating at cast(ing) surface.

The corrosion resistance of experimental example gained coating of the present invention detects

(1) sample preparation.The prismatic sample of preparation length of side 8mm, long 20mm, cleans post-drying with water.Cylinder top is applied one deck epoxy resin without coat side, solidifies the original weight of rear measurement sample, calculate its surface area.

(2) corrosive medium preparation.Be that the analytical pure sulfuric acid of 98% mixes with the deionized water of certain volume with mass fraction, the corrosive liquid of preparation pH=3.

(3) corrosion test.To try to please the beaker amassed as 500ml, clean post-drying with distilled water, add the H prepared ₂sO4 solution, puts into sample.Beaker is put into the insulating box of 25 DEG C, every other day change a corrosive liquid, take out sample respectively after 72,120,168,240 and 336 hours, cleaning sample surfaces also weighs its weight.

(4) interpretation of result.Adopt weight-loss method to analyze the corrosion resistance of coating, calculate average corrosion rate with following formula:

$v=\frac{m_0-m_1}{S\·t}$

In formula, v is corrosion rate (g/m ²h), m ₀for the weight (g) before sample corrosion, m ₁for the weight (g) after corrosion product removed by sample, S is the long-pending (m of specimen surface ²), t is etching time (h).

Adopt said method to carry out corrosion resistance detection to the embodiment of the present invention 3,4 and 5 gained coating, not add the primary sample product in contrast of coating, testing result is in table 1.

Corrosion rate (the g/m of table 1 each sample different time points ²h)

Can be obtained by table 1 result, gained coating sample of the present invention does not significantly corrode generation in first 72 hours what soak, and at 336 hours, corrosion rate was about 52.4 ~ 60% of primary sample, and corrosion resistant performance significantly improves.

Claims (9)

1. one kind contains Al ₂o ₃aluminum alloy cast ooze with coating, it is characterized in that, its primarily of following weight ratio component made by:

25 ~ 45 parts of Al ₂o ₃, 40 ~ 60 parts of CrO ₃, 3 ~ 10 parts of fused salts, 3 ~ 6 parts of sodium fluorides, 1 ~ 3 part of binding agent.

2. according to claim 1 containing Al ₂o ₃aluminum alloy cast ooze with coating, it is characterized in that, its primarily of following weight ratio component made by:

30 ~ 40 parts of Al ₂o ₃, 45 ~ 55 parts of CrO ₃, 5 ~ 8 parts of fused salts, 3 ~ 6 parts of sodium fluorides, 1 ~ 3 part of binding agent.

3. according to claim 1 containing Al ₂o ₃aluminum alloy cast ooze with coating, it is characterized in that, its primarily of following weight ratio component made by:

35 parts of Al ₂o ₃, 52 parts of CrO ₃, 7 parts of fused salts, 4 parts of sodium fluorides, 2 parts of binding agents.

4. according to claim 1 containing Al ₂o ₃aluminum alloy cast ooze with coating, it is characterized in that, described Al ₂o ₃particle size>=250 order.

5. according to claim 1 containing Al ₂o ₃aluminum alloy cast ooze with coating, it is characterized in that, described fused salt is by NaCl, KCl and MgCl ₂by mole than being 18:47:35 composition.

6. according to claim 1 containing Al ₂o ₃aluminum alloy cast ooze with coating, it is characterized in that, described binding agent is sodium carboxymethylcellulose or polyvinyl alcohol.

7. utilize described in any one of claim 1-6 containing Al ₂o ₃aluminum alloy cast ooze with coating prepare casting impregnation coating method, it is characterized in that, comprise the following steps:

(1) Al is got ₂o ₃, CrO ₃, fused salt, sodium fluoride and binding agent mix, add pure water and make coating;

(2) above-mentioned coating is coated in casting mold die cavity or core surface, dries under temperature is 100 ~ 120 DEG C of conditions;

(3) melted aluminium liquid is poured into above-mentioned die cavity or core surface, the coating on aluminium liquid and die cavity or core surface interacts, and namely obtains described coating at cast(ing) surface.

8. the method preparing casting impregnation coating according to claim 7, it is characterized in that, described casting mold is waterglass sand mold, resin bonded sand mould or core.

9. the method preparing casting impregnation coating according to claim 7, it is characterized in that, described pouring temperature is 720 ~ 750 DEG C.