Metal microarc oxidation electrolyte and method for forming black ceramic coating on metal surface by microarc oxidation

Abstract

The invention discloses a metal microarc oxidation electrolyte and a method for forming a black ceramic coating on a metal surface by microarc oxidation, belonging to the technical field of metal surface treatment. The electrolyte comprises sodium silicate, sodium fluoride, potassium hydroxide, sodium citrate, sodium tungstate and pigment, carbon black. The method for forming the black ceramic coating on the metal surface by microarc oxidation comprises the following steps: carrying out pretreatment on a sample, preparing a electrolyte electrolyte, setting electrical parameters, turning of a circulating cooling water device, connecting the sample with a conducting rod, immersing the sample in the electrolyte to be as the anode, using a stainless steel electrolytic tank doubling as the cathode, switching on a bidirectional pulse power supply to carry out microarc oxidation treatment, then washing the treated sample with deionized water to obtain a black ceramic membrane layer, and then carrying out air drying naturally. The prepared metal surface black ceramic membrane layer has high black degree, uniform color, large thickness value, high density and hardness of the membrane layer, and good bonding strength with the metal matrix. The preparation process of the electrolyte is easy to operate, and is beneficial to realize batch production and industrial applications.

Description

technical field

[0001] The invention belongs to the technical field of metal surface treatment, and in particular relates to a metal micro-arc oxidation electrolyte and a method for surface black ceramicization. . Background technique

[0002] Micro-arc oxidation (also known as micro-plasma oxidation) is a kind of instantaneous high-temperature and high-pressure action generated by arc discharge on the surface of aluminum, magnesium, titanium, zirconium, tantalum, niobium and their alloys through the combination of electrolyte and corresponding electrical parameters. A new surface treatment technology that in-situ grows a ceramic film layer based on a matrix metal oxide. The prepared ceramic film layer is firmly combined with the substrate, has a compact structure, high toughness, and has good properties such as wear resistance, corrosion resistance, high temperature impact resistance, electrical insulation and the like. Micro-arc oxidation technology is easy to implement...

Examples

Embodiment 1

[0023] The sample selected is AZ91D magnesium alloy, and its shape is a sheet of 30mm×30mm×5mm. The specific preparation process conditions and operation steps are as follows:

[0024] 1. Sample pretreatment: The surface of the magnesium alloy sample is polished smoothly with 400#, 600#, 800# and 1000# sandpaper, then degreasing in acetone, rinsed with deionized water, and dried for later use;

[0025] 2. Electrolyte preparation: prepare 2L of electrolyte solution, the concentration of each component in the electrolyte is 6.0g / L sodium silicate, 2.0g / L potassium hydroxide, 2.0g / L sodium fluoride, 2.0g / sodium tungstate / L. Sodium citrate 0.5g / L, carbon ink 25.0mL / L;

[0026] 3. Electric parameter setting: adopt constant current mode, current density 2A / dm 2 , Frequency 600Hz, duty ratio 20%, cathode and anode current density ratio 1.0, reaction time 20min;

[0027] 4. Micro-arc oxidation: turn on the circulating cooling water device, connect the magnesium alloy sample to the conductive...

Embodiment 2

[0033] The sample selected is AZ91D magnesium alloy, and its shape is a sheet of 30mm×30mm×5mm. The specific preparation process conditions and operation steps are as follows:

[0034] 1. Sample pretreatment: same as Example 1;

[0035] 2. Electrolyte preparation: prepare 2L of electrolyte solution, the concentration of each component in the electrolyte is sodium silicate 8.0g / L, potassium hydroxide 2.0g / L, sodium fluoride 2.0g / L, sodium tungstate 1.0g / L. Sodium citrate 0.3g / L, carbon ink 20.0mL / L;

[0036] 3. Electric parameter setting: adopt constant current mode, current density 1A / dm 2 , Frequency 600Hz, duty ratio 20%, cathode and anode current density ratio 1.0, reaction time 15min;

[0037] 4. Micro-arc oxidation: same as Example 1;

[0038] 5. Post-processing: the same as in Example 1.

[0039] The prepared samples were evaluated and characterized, and it was found that the surface of the ceramic film of the sample was smooth and the whole body was jet-black, and the blackness ...

Embodiment 3

[0041] The sample selected is AZ91D magnesium alloy, and its shape is a sheet of 30mm×15mm×5mm. The specific preparation process conditions and operation steps are as follows:

[0042] 1. Sample pretreatment: same as Example 1;

[0043] 2. Electrolyte preparation: prepare 2L of electrolyte solution, the concentration of each component in the electrolyte is sodium silicate 10.0g / L, potassium hydroxide 2.0g / L, sodium fluoride 3.0g / L, sodium tungstate 1.5g / L. Sodium citrate 0.9g / L, carbon ink 15.0mL / L;

[0044] 3. Electric parameter setting: adopt constant current mode, current density 3A / dm 2 , Frequency 600Hz, duty ratio 20%, cathode and anode current density ratio 1.0, reaction time 15min;

[0045] 4. Micro-arc oxidation: same as Example 1;

[0046] 5. Post-processing: the same as in Example 1.

[0047] The prepared samples were evaluated and characterized, and it was found that the surface of the ceramic film of the sample was smooth and the whole body was jet black, and the blackness...

technical field

[0001] The invention belongs to the technical field of metal surface treatment, and in particular relates to a metal micro-arc oxidation electrolyte and a method for surface black ceramicization. . Background technique

[0002] Micro-arc oxidation (also known as micro-plasma oxidation) is a kind of instantaneous high-temperature and high-pressure action generated by arc discharge on the surface of aluminum, magnesium, titanium, zirconium, tantalum, niobium and their alloys through the combination of electrolyte and corresponding electrical parameters. A new surface treatment technology that in-situ grows a ceramic film layer based on a matrix metal oxide. The prepared ceramic film layer is firmly combined with the substrate, has a compact structure, high toughness, and has good properties such as wear resistance, corrosion resistance, high temperature impact resistance, electrical insulation and the like. Micro-arc oxidation technology is easy to implement...

Examples

Embodiment 1

[0023] The sample selected is AZ91D magnesium alloy, and its shape is a sheet of 30mm×30mm×5mm. The specific preparation process conditions and operation steps are as follows:

[0024] 1. Sample pretreatment: The surface of the magnesium alloy sample is polished smoothly with 400#, 600#, 800# and 1000# sandpaper, then degreasing in acetone, rinsed with deionized water, and dried for later use;

[0025] 2. Electrolyte preparation: prepare 2L of electrolyte solution, the concentration of each component in the electrolyte is 6.0g / L sodium silicate, 2.0g / L potassium hydroxide, 2.0g / L sodium fluoride, 2.0g / sodium tungstate / L. Sodium citrate 0.5g / L, carbon ink 25.0mL / L;

[0026] 3. Electric parameter setting: adopt constant current mode, current density 2A / dm 2 , Frequency 600Hz, duty ratio 20%, cathode and anode current density ratio 1.0, reaction time 20min;

[0027] 4. Micro-arc oxidation: turn on the circulating cooling water device, connect the magnesium alloy sample to the conductive...

Embodiment 2

[0033] The sample selected is AZ91D magnesium alloy, and its shape is a sheet of 30mm×30mm×5mm. The specific preparation process conditions and operation steps are as follows:

[0034] 1. Sample pretreatment: same as Example 1;

[0035] 2. Electrolyte preparation: prepare 2L of electrolyte solution, the concentration of each component in the electrolyte is sodium silicate 8.0g / L, potassium hydroxide 2.0g / L, sodium fluoride 2.0g / L, sodium tungstate 1.0g / L. Sodium citrate 0.3g / L, carbon ink 20.0mL / L;

[0036] 3. Electric parameter setting: adopt constant current mode, current density 1A / dm 2 , Frequency 600Hz, duty ratio 20%, cathode and anode current density ratio 1.0, reaction time 15min;

[0037] 4. Micro-arc oxidation: same as Example 1;

[0038] 5. Post-processing: the same as in Example 1.

[0039] The prepared samples were evaluated and characterized, and it was found that the surface of the ceramic film of the sample was smooth and the whole body was jet-black, and the blackness ...

Embodiment 3

[0041] The sample selected is AZ91D magnesium alloy, and its shape is a sheet of 30mm×15mm×5mm. The specific preparation process conditions and operation steps are as follows:

[0042] 1. Sample pretreatment: same as Example 1;

[0043] 2. Electrolyte preparation: prepare 2L of electrolyte solution, the concentration of each component in the electrolyte is sodium silicate 10.0g / L, potassium hydroxide 2.0g / L, sodium fluoride 3.0g / L, sodium tungstate 1.5g / L. Sodium citrate 0.9g / L, carbon ink 15.0mL / L;

[0044] 3. Electric parameter setting: adopt constant current mode, current density 3A / dm 2 , Frequency 600Hz, duty ratio 20%, cathode and anode current density ratio 1.0, reaction time 15min;

[0045] 4. Micro-arc oxidation: same as Example 1;

[0046] 5. Post-processing: the same as in Example 1.

[0047] The prepared samples were evaluated and characterized, and it was found that the surface of the ceramic film of the sample was smooth and the whole body was jet black, and the blackness...

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