CN1137942C - Paint for prepn. of aluminium oxide ceramic coating layer and its coating method - Google Patents

Abstract

The present invention relates to paint and a method thereof, which belongs to the technical field of mechanical engineering surface treatment. The method comprises the following steps: firstly, a water solution of phosphoric acid and aluminum hydroxide is prepared; then a water solution of phosphoric acid and sodium silicate is prepared; finally, treated diaspore, ceramic and solid particles of other materials are proportionally mixed with the two solutions to be prepared into the paint. The paint is coated on the surface of aluminium alloy in a brush coating or spray coating mode and is heated at an environmental temperature of 200 DEG C; the coating and heat treatment processes are circularly carried out, and a coating layer is formed on the surface of a basal body. The paint has the advantages of low treatment temperature, relative simple technological condition, low cost, no pollution, wear resistance, corrosion resistance, heat resistance, etc.

Description

The coating and the coating method thereof of preparation aluminium oxide ceramic coating layer

The invention belongs to the mechanical engineering technical field of surface.Be particularly related to the surface strengthening that is used for aluminum alloy materials and a kind of preparation method of surface coating of surface protection.

The known method for preparing ceramic coating on alloy matrix aluminum has the differential arc oxidation method, electrochemical process, laser treatment method, hot-spraying techniques etc. at present.The some of them method needs complex apparatus, and other or technology are restive, and perhaps the coating formation temperature is too high, and it is used and all is subjected to certain limitation.

Original position thermal chemical reaction method is the class novel surface treatment technology that development in recent years is got up.The reaction in type is a lot, comprising decomposition in situ reaction, add in-place and reaction and original position replacement(metathesis)reaction.The proposition of this coat preparing technology provides developing direction for form ceramic coating under relatively lower temp.Its characteristics are: coat preparing technology and processing condition are simple relatively; Low cost, applied range; Temperature required lower; Can obtain the coating good with matrix bond; The coat-thickness may command, coating performance can be optimized as required.Mu Baichun etc. utilize original position displacement reaction method with Al ₂O ₃, MgO and ZrSiO ₄For feedstock production has gone out ZrO ₂, Al ₆Si ₂O ₁₃And MgAl ₂O ₄Deng complex phase ceramic coating.Employing in-situ reactions such as Ceng Aixiang have prepared α-Al ₂O ₃, TiO ₂, Fe ₃B and Al ₄Ti ₂SiO ₁₂Complex phase ceramic coating.But the formation temperature of both coatings is higher, is about 800 ℃.Church applies and heat treated by the chemistry that porose ceramic matrix material is carried out repeatedly in its patent (United State Patent No.3734767), compound as solvent is transformed on the spot, formation has certain thickness new high rigidity stupalith (Mohs' hardness can reach 9) on the surface after repeatedly circulating, treatment temp is generally 316 ℃～538 ℃ (600 °F～1000 °F), and cycle index reaches 11 times.Collis has reported the original position thermochemistry coating production at metal matrix material, and the coating preparation process is similar to the method for aforementioned Church, uses group water solution that matrix is repeatedly applied and heat treated, and treatment temp is 500 ℃.It is too high more with cycle index that the common issue with that both exist remains post-processing temperature.Too high treatment temp will inevitably cause very adverse influence to the performance of alloy matrix aluminum material.At this problem, the present inventor utilizes the valence state transforming principle of chromic oxide to prepare chromic oxide-based ceramic coating on alloy matrix aluminum under 200 ℃ of conditions in invention early, and formation mechanism, coating structure and the coating tribological property under normal temperature and high temperature (400 ℃) condition of coating carried out preliminary study, obtained comparatively satisfied result.But normally contain the chromic soluble chromium compound that can cause severe contamination to environment owing to generate the presoma of chromium oxide coating, this has just limited the range of application of this method greatly.

The objective of the invention is environment to be polluted etc. not enough in order to overcome the too high or coated substance of prior art or coating formation temperature.In order to reach this purpose, the present invention replaces hexavalent chromium compound as presoma with free of contamination diaspore, has developed a kind of novel coating and coating method thereof.Utilize above-mentioned coating and coating method thereof, can on alloy matrix aluminum, prepare aluminium oxide ceramic coating layer.The present invention has advantages such as coating treatment temp low (heat affecting to body material is little), processing condition are simple relatively, cost is low, wear-resisting, anti-corrosion, heat-resisting, pollution-free.

The preparation method for coating that is used for preparing aluminium oxide ceramic coating layer that the present invention proposes in aluminum alloy surface, its feature comprises following concrete steps:

1, obtain solution A

Take by weighing aluminium hydroxide according to following prescription, phosphoric acid and water mix post-heating to more than 100-120 ℃, stir, and insulation got required solution more than 1 hour.

Phosphoric acid (H ₃PO ₄) 60-140ml/l

Aluminium hydroxide (Al (OH) ₃) 20-45g/l

Water (H ₂O) supply surplus

2, obtain solution B

Take by weighing water glass according to following prescription, phosphoric acid and water left standstill after mixing more than 24 hours, got required solution.

Phosphoric acid (H ₃PO ₄) 5-20ml/l

Water glass (Na ₂SiO ₃) 3-12g/l

Water (H ₂O) supply surplus

3, at first take by weighing through pretreated diaspore powder, with solia particle thorough mixing ceramic and other material, add solution A, B then again, stir, obtain needed coating S by following prescription.

Diaspore β-AlOOH 200-500g/l

Aluminium oxide Al ₂O ₃100-400g/l

Titanium oxide TiO ₂0-80g/l

Cerium oxide CeO ₂0-10g/l

Solution A 250-450ml/l

The same volume of solution B and solution A

Water H ₂O supplies surplus

Described diaspore pre-treatment can be adopted following method:

At first clean and remove impurity, under 60 ℃ envrionment temperature, dry then, calcined 10 minutes down at 400 ℃ again with aqueous hydrochloric acid.

The present invention adopts the coating method of above-mentioned coating, it is characterized in that, above-mentioned coating is coated on the aluminum alloy surface heat treated under 200-220 ℃ of envrionment temperature in the mode of brushing or spray.Circulate above-mentioned coating and heat-treatment process form coating at matrix surface.Specifically may further comprise the steps:

1, adopt mechanical grinding and alkali lye oil removing clear base surface, adopt acid wash activation matrix surface then:

2, coating is imposed on matrix surface equably in the mode of brushing or spray, thickness should not be too big, and general each coating thickness is about 20-30 μ m;

3, the test specimen that will scribble coating places the uniform temperature environment (barometric point) about 200 ℃, and the hold-time was generally 2-3 hour;

4, test specimen naturally cools to room temperature in air:

5, repeating step 2-4, multiplicity is decided according to the coat-thickness of design in advance, generally is advisable with 3-6 time;

6, formed coatingsurface is machined to required smooth finish, its method can adopt polishing or add the water polishing with waterproof abrasive paper.

Performance of the present invention and effect:

The present invention is with prepared phosphoric acid, aluminium hydroxide and sodium silicate aqueous solution and diaspore, pottery (aluminum oxide, titanium oxide etc.) and the solia particle of other material (cerium oxide etc.) are mixed and made into coating in advance; above-mentioned solia particle is of a size of micron or submicron order; coating is imposed on aluminium alloy matrix surface repeatedly in the mode of brushing; and heat treated at a certain temperature; by means of in the inner series of chemical that takes place of aluminum alloy surface and coating and original position generates aluminium oxide ceramic coating layer, the solia particle disperse of adding in the coating is distributed in wherein.Coating is to generate new material by chemical reaction to realize that its bonding strength depends on the intensity of resultant of reaction with combining of matrix.

The coating of preparing with the method for the invention, be combined into Chemical bond between coating and the matrix, sem observation is the result show, on coating and basal body interface, owing to the material in the coating and body material generation chemical reaction exist a transitional region, its thickness is approximately 3-5 μ m, in this zone of transition, multiple element coexistence such as oxygen, phosphorus and aluminium, coating and matrix bond are good.Exist the dispersive micropore in the coating, these holes are that the gas evolution that generates owing to chemical reaction in coating forming procedure causes.The existence of micropore can cause coating subsurface defect and unrelieved stress, reduces the intensity of coating.For the coating of repeatedly circulation coating preparation, the micropore that preceding once circulation is produced is clogged by circular treatment coating thereafter, plays " casting anchor " effect, helps the combination of coating.X-ray diffraction analysis is the result show, coating is a heterogeneous structure, and multiple composition is also deposited, and essential substance wherein is α-Al ₂O ₃Coat-thickness can be adjusted by increasing the circular treatment number of times as required, and scope is 50-200 μ m, and the coating micro-hardness is HV300-500, can prepare different coating by adding different solia particles, thereby obtain different coating performances.Compare with at present domestic and international existing similar technology, present technique has advantages such as treatment temp low (heat affecting to body material is little), processing condition are simple relatively, cost is low, pollution-free.

The present invention is workable, both can be applicable to industrial circle, also can be used for the decoration and the protection of aluminium and alloy thereof.Also can further expand and be applied to other light metal alloy materials and ferrous materials etc.

Embodiment one

Formulation for coating material is as follows:

Water solution A 01:

Phosphoric acid (H ₃PO ₄) 120ml/l

Aluminium hydroxide (Al (OH) ₃) 40g/l

Water (H ₂O) supply surplus

Aqueous solution B01:

Phosphoric acid (H ₃PO ₄) 12ml/l

Water glass (Na ₂SiO ₃) 8g/l

Water (H ₂O) supply surplus

Coating S01:

Diaspore (the 400g/l of β-AlOOH)

Aluminum oxide (Al ₂O ₃) 300g/l

Solution A 400ml/l

Solution B 400ml/l

Water (H ₂O) supply surplus

Matrix is selected the LY-12 aluminium alloy for use.Adopt mechanical grinding and alkali lye oil removing to make the smooth cleaning of matrix, and adopt acid wash activation matrix surface.Coating S01 is imposed on matrix surface repeatedly with the method for brushing, prepared coating under 200 ℃ of conditions, after 4 circular treatment, coat-thickness is about 100 μ m, and the average vickers hardness hv of coating is about 400.The appearance of coat color is light chocolate.

Embodiment two

Formulation for coating material is as follows:

Water solution A 02:

Phosphoric acid (H ₃PO ₄) 70ml/l

Aluminium hydroxide (Al (OH) ₃) 25g/l

Water (H ₂O) supply surplus

Aqueous solution B02:

Phosphoric acid (H ₃PO ₄) 10ml/l

Water glass (Na ₂SiO ₃) 5g/l

Water (H ₂O) supply surplus

Coating S02:

Diaspore (the 250g/l of β-AlOOH)

Aluminum oxide (Al ₂O ₃) 150g/l

Solution A 300ml/l

Solution B 300ml/l

Water (H ₂O) supply surplus

Matrix is selected the LY-12 aluminium alloy for use.Adopt mechanical grinding and alkali lye oil removing to make the smooth cleaning of matrix, and adopt acid wash activation matrix surface.Coating S02 is imposed on matrix surface repeatedly with the method that sprays, prepared coating under 200 ℃ of conditions, through 4 circular treatment, coat-thickness is about 80 μ m, and the average vickers hardness hv of coating is about 350.The appearance of coat color is light chocolate.

Embodiment three

Formulation for coating material is as follows:

Water solution A 01:

Phosphoric acid (H ₃PO ₄) 120ml/l

Aluminium hydroxide (Al (OH) ₃) 40g/l

Water (H ₂O) supply surplus

Aqueous solution B01:

Phosphoric acid (H ₃PO ₄) 12ml/l

Water glass (Na ₂SiO ₃) 8g/l

Water (H ₂O) supply surplus

Coating S01:

Diaspore (AlOOH) 300g/l

Aluminum oxide (Al ₂O ₃) 300g/l

Titanium oxide TiO ₂30g/l

Cerium oxide CeO ₂4g/l

Solution A 350ml/l

Solution B 350ml/l

Water (H ₂O) supply surplus

Matrix is selected the LY-12 aluminium alloy for use.Adopt mechanical grinding and alkali lye oil removing to make the smooth cleaning of matrix, and adopt acid wash activation matrix surface.Coating S01 is imposed on matrix surface repeatedly with the method for brushing, prepared coating under 200 ℃ of conditions, after 6 circular treatment, coat-thickness is about 150 μ m, and the average vickers hardness hv of coating is about 400.The appearance of coat color is light chocolate.

Claims (2)

1, a kind of preparation method for coating for preparing aluminium oxide ceramic coating layer is characterized in that:

A, take by weighing aluminium hydroxide according to following prescription, phosphoric acid and water mix post-heating to more than 100-120 ℃, stir, and insulation is more than 1 hour, solution A, wherein:

Phosphoric acid H ₃PO ₄60-140ml/l

Aluminium hydroxide Al (OH) ₃20-45g/l

Water H ₂O supplies surplus;

B, take by weighing water glass according to following prescription, phosphoric acid and water left standstill after mixing more than 24 hours, solution B, wherein:

Phosphoric acid H ₃PO ₄5-20ml/l

Water glass Na ₂SiO ₃3-12g/l

Water H ₂O supplies surplus;

C, at first take by weighing through pretreated diaspore powder, with the solia particle thorough mixing of pottery and other material, add solution A, B then again, stir, obtain needed coating by following prescription, wherein:

Diaspore β-AlOOH 200-500g/l

Aluminium oxide Al ₂O ₃100-400g/l

Titanium oxide TiO ₂0-80g/l

Cerium oxide CeO ₂0-10g/l

Solution A 250-450ml/l

The same volume of solution B and solution A

Water H ₂O supplies surplus;

The pretreatment technology of the described diaspore of step c comprises: at first clean with aqueous hydrochloric acid and remove impurity, dry under 60 ℃ envrionment temperature then, calcined 10 minutes down at 400 ℃.

2, a kind of coating method of the coating according to claim 1 preparation is characterized in that, with above-mentioned coating to brush or the mode of spraying is coated on the aluminum alloy surface heat treated under 200-220 ℃ of envrionment temperature; Circulate above-mentioned coating and heat-treatment process form aluminium oxide ceramic coating layer at matrix surface; Specifically may further comprise the steps:

A, employing mechanical grinding and alkali lye oil removing clear base surface are adopted acid wash activation matrix surface then;

B, with coating to brush or the mode of spraying imposes on matrix surface equably, thickness should not be too big, general each coating thickness is about 20-30 μ m;

C, the test specimen that will scribble coating place 200 ℃ uniform temperature environment (barometric point), and the hold-time was generally 2-3 hour;

D, test specimen naturally cool to room temperature in air;

E, repeating step 2-4, multiplicity is decided according to the coat-thickness of design in advance, generally is advisable with 3-6 time;

F, formed coatingsurface is machined to required smooth finish.