CN104962911A - Novel process technology method for improving corrosion resistance of magnesium alloy - Google Patents
Novel process technology method for improving corrosion resistance of magnesium alloy Download PDFInfo
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- CN104962911A CN104962911A CN201510391803.9A CN201510391803A CN104962911A CN 104962911 A CN104962911 A CN 104962911A CN 201510391803 A CN201510391803 A CN 201510391803A CN 104962911 A CN104962911 A CN 104962911A
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Abstract
The invention provides a novel process technology method for surface treatment and an application in protection of magnesium-alloy surface. The technology method is characterized in that a compact microcrystallized Ni-Cr alloy layer is prepared and obtained on the magnesium-alloy surface by a high-energy micro-arc alloying technology, a coating layer and a basal body have good bonding strength and can block the permeation of corrosive mediums effectively so as to provide high-quality protection for the magnesium alloy. The process technology method comprises the following main steps of: adopting a Ni-Cr alloy electrode prepared by non-consumable electric-arc smelting under the protection of argon gas as a rotating electrode, adjusting proper deposition process parameters by the high-energy micro-arc alloying technology, and when the set process parameters are as follows: the power is 1500W, the voltage is 70-90V, the frequency is 400-600Hz, the pulse width is 200-400mus, the rotating speed is 1500-3500r/min, the protective-gas flow is 10-15L/min, the deposition time is 2min, and obtaining a uniform and compact Ni-Cr layer with the thickness being 20-40mum on the surface of the magnesium-alloy surface. The novel process technology provided by the invention has the advantages that the problems that the bonding force of the coating layer and the basal body is poor since the magnesium alloy is obtained by adopting surface treatment technologies such as electroplating and chemical plating and the magnesium alloy can be rapidly oxidized in water solution due to high activity and the like are overcome; and the novel process technology method has very-high practical value for improving the protective performance of the magnesium-alloy surface.
Description
Technical field
The invention belongs to the surface modification treatment category of magnesium alloy materials, be related specifically to and adopt metallic coating as the technology method of protective coating at Mg alloy surface.
Background technology
Magnesium alloy due to its density little, specific tenacity is high, larger than Young's modulus, and electrical and thermal conductivity performance is good, and shock absorbing is good, the feature that the loading capacity that withstands shocks is large, has been widely used in the departments such as Aeronautics and Astronautics, transport, chemical industry, automobile, medicine at present.But its corrosion resisting property is poor, make using and develop and being subject to serious obstruction of magnesium alloy.At present, must carry out suitable surface treatment to magnesium alloy in actual applications, this has become indispensable committed step.Conventional surface treatment method of Mg alloy has: chemical treatment; Anodic oxidation; Metallic coating; Laser treatment; Ion implantation etc.Wherein metal plating is carried out to magnesium alloy and be proved to be a kind of efficiently feasible method, but making magnesium alloy become the metal of the most difficult plating due to following reason: (1) Mg alloy surface is very easily oxidized and forms the loose zone of oxidation of one deck, easy-clear is unclean, has a strong impact on coating and basal body binding force; (2) electrochemical activity of magnesium is too high, all can corrode rapidly in all acidic baths, and very strong with the replacement(metathesis)reaction of other metal ion, and the coating after displacement combines very loose; (3) second-phase in magnesium alloy (as equal in rare-earth phase, γ) has different electrochemical properties, and coating may be caused uneven; (4) current potential of magnesium alloy substrate is very low, and the standard potential of coating will much larger than matrix, if there is through hole in coating, can corrosion current be increased, serious galvanic corrosion can be caused, and in magnesium alloy, the existence of impurity may become the source in coating space.The present invention adopts a kind of method of novel raising corrosion stability of magnesium alloy, and obtain the Ni-Cr coating of one deck even compact at magnesium alloy matrix surface, it is simple to operate, and preparation cost is low, practical, and increases significantly to matrix solidity to corrosion.This can provide a kind of new method for improving corrosion stability of magnesium alloy.
Summary of the invention
Technical problem to be solved by this invention is, overcomes magnesium alloy and adopts the process for treating surface such as plating, electroless plating to obtain coating and basal body binding force is poor and due to the high activity problem such as rapid oxidation in aqueous of magnesium alloy itself.There is provided a kind of and form one deck even compact at Mg alloy surface, the strong and a kind of new technological method of the coating of good corrosion resistance of bonding force.
The technical solution used in the present invention detailed process is as follows:
Step one: magnesium alloy is carried out pre-treatment, pre-mill is polished successively with 500 to 2000 order sand paper and removes superficial oxidation layer, then put into acetone soln ultrasonic assistant cleaning 3-5min, dry up with cold wind by washed with de-ionized water, put into moisture eliminator with for subsequent use.
Step 2: select Ni, Cr pure metal (purity: 99.99at%) and (wherein Cr content is 18at.% by non-consumable arc melting method acquisition Ni-18Cr electrode bar, atomic ratio), then, after annealing 24 hours in 850 DEG C of argon gas, take out as rotating electrode.Adopt 200 order sand paperings to remove zone of oxidation to light to the surface treatment of depositing electrode, then put into acetone soln ultrasonic cleaning 3-5min, dry up with cold wind by washed with de-ionized water after taking-up.
Step 3: differential of the arc alloying technology process prepares the process adjustments of Ni-Cr alloy layer: setting deposition voltage is 70-90V; Frequency is 400-600Hz; Pulsewidth is 200-400 μ s; Dutycycle: 5-15%; Power is 1500W.Controlling rotating electrode rotating speed is 1500-3500r/min, and gas flow argon flow amount is under the protection of 10-15L/min.At Mg alloy surface deposition 2min, can obtain a layer thickness on surface the Ni-Cr coating of 20-40 μm, coating uniform is fine and close and bonding strength is high.
Described magnesium alloy to be protected is selected from the AZ series diecast magnesium alloy comprising AZ91, AZ31 trade mark.Its preprocessing process is: polish successively to magnesium alloy with 500 to 2000 order sand paper on pre-mill, then puts into acetone soln ultrasonic assistant cleaning 3-5min, dries up with deionized water rinsing with cold wind.
What described rotating electrode adopted is Ni-Cr alloy, and its preparation process is: select Ni, Cr pure metal, its purity is: 99.99at%.The alloy ratio (wherein Cr content is 18at.%, atomic ratio) of good Ni and the Cr of proportioning, obtains Ni-18Cr electrode bar by non-consumable arc melting method, after then annealing 24 hours in 850 DEG C of argon gas, takes out as rotating electrode.Adopt 200 order sand paperings to remove zone of oxidation to light to the surface treatment of depositing electrode, then put into acetone soln ultrasonic cleaning 3-5min, dry up with cold wind by washed with de-ionized water after taking-up.Described Ni-Cr electrode diameter is Φ 1-5mm, and length is 20-100mm.
Described high energy differential of the arc alloying technology is: deposition power supply selects unidirectional pulse power supply, sets deposition parameter: voltage is 70-90V under rated output 1500W; Electric current pulsewidth is 200-400 μ s; Frequency is 400-600Hz; Dutycycle is 5-15%; Depositing time is 2min; Electrode rotary speed is 1500-3500r/min.
Described protective gas is argon gas, and its purity is greater than 99%, and work output is 10-15L/min.
The micritization Ni-Cr coat-thickness that the present invention is prepared at Mg alloy surface is at 20-40 μm, and effective environmental contaminants and the etchant solution of stoping arrives magnesium alloy substrate, can increase substantially the corrosion resisting property of magnesium alloy.And the Ni-Cr metallic coating that the present invention is obtained by electric spark deposition technology and magnesium alloy bonding force strong, be typical metallurgical binding.To be-0.56V to have shuffled nearly 1000mV compared to the corrosion potential (about-1.5V) of magnesium alloy for the corrosion potential of Ni-Cr coating of preparation, corrosion current also reduces 5 orders of magnitude, and the Ni-Cr coating after modification can provide effective protection for a long time to magnesium alloy substrate.
Accompanying drawing illustrates:
Fig. 1 is Ni-Cr coating cross sections pattern prepared by AZ91D magnesium alloy
Fig. 2 is the dynamic potential polarization curve of surperficial Ni-Cr coating in 3.5%NaCl solution of AZ91D magnesium alloy substrate and preparation
Embodiment:
The matrix of electric spark deposition is sheet magnesium alloy test button, and it adopts size to be: the wide * of long * is high: 10mm*10mm*5mm.
Embodiment 1:
AZ91D magnesium alloy sample is polished successively with 500 to 2000 object sand paper respectively, removes zone of oxidation, and sample is put into acetone soln ultrasonic assistant cleaning 3-5min.Then use washed with de-ionized water, cold wind dries up.Ni, Cr pure metal is carried out proportioning by 0.82:0.18 (atomic ratio), and carry out melting by non-consumable vacuum melting furnace, obtain the long rod of the Ni-18Cr alloy electrode for 3mm*100mm size of diameter *, then after annealing 24 hours in 850 DEG C of argon gas, take out as rotating electrode, and carry out polishing removal zone of oxidation with 200 order sand paper, and put into acetone soln ultrasonic assistant cleaning 3-5min.Then use washed with de-ionized water, cold wind dries up.
Alloy coat forming process: using AZ91D magnesium alloy sample good for pre-treatment as body material, be used as the negative electrode in deposition process and connect the negative electrode of pulse power equipment, Ni-Cr electrode is connected on deposition-gun as anode, rotate after energising, regulate processing parameter: under rated output 1500W, setting deposition voltage is 70V; Frequency is 400Hz; Pulsewidth is 200 μ s; Dutycycle 5%; Argon flow amount is 15L/min, electrode rotary Speed Setting is 1500r/min, depositing time is 2min, during deposition, adjustment deposition-gun and matrix are to guarantee that whole surface of test piece all obtains coating, coat-thickness can be obtained the Ni-18%Cr coating of about 40 μm, coatingsurface dense uniform, has good corrosion resistance.
Embodiment 2
AZ91D magnesium alloy sample is polished successively with 500 to 2000 object sand paper respectively, removes zone of oxidation, and sample is put into acetone soln ultrasonic assistant cleaning 3-5min.Then use washed with de-ionized water, cold wind dries up.Ni, Cr pure metal is carried out proportioning by 0.82:0.18, and carry out melting by non-consumable vacuum melting furnace, obtain the long rod of the Ni-18Cr alloy electrode for 3mm*100mm size of diameter *, then after annealing 24 hours in 850 DEG C of argon gas, take out as rotating electrode, and carry out polishing removal zone of oxidation with 200 order sand paper, and put into acetone soln ultrasonic assistant cleaning 3-5min.Then use washed with de-ionized water, cold wind dries up.
Alloy coat forming process: using AZ91D magnesium alloy sample good for pre-treatment as body material, be used as the negative electrode in deposition process and connect the negative electrode of pulse power equipment, Ni-Cr electrode is connected on deposition-gun as anode, rotate after energising, regulate processing parameter: under rated output 1500W, setting deposition voltage is 80V; Frequency is 500Hz; Pulsewidth is 300 μ s; Dutycycle 10%; Argon flow amount is 15L/min, electrode rotary Speed Setting is 2500r/min, depositing time is 2min, during deposition, adjustment deposition-gun and matrix are to guarantee that whole surface of test piece all obtains coating, coat-thickness can be obtained the Ni-18%Cr coating of about 30 μm, coatingsurface dense uniform, has good corrosion resistance.
Embodiment 3
AZ91D magnesium alloy sample is polished successively with 500 to 2000 object sand paper respectively, removes zone of oxidation, and sample is put into acetone soln ultrasonic assistant cleaning 3-5min.Then use washed with de-ionized water, cold wind dries up.Ni, Cr pure metal is carried out proportioning by 1:0.18, and carry out melting by non-consumable vacuum melting furnace, obtain the long rod of the Ni-18%Cr alloy electrode for 3mm*100mm size of diameter *, then after annealing 24 hours in 850 DEG C of argon gas, take out as rotating electrode, and carry out polishing removal zone of oxidation with 200 order sand paper, and put into acetone soln ultrasonic assistant cleaning 3-5min.Then use washed with de-ionized water, cold wind dries up.
Alloy coat forming process: using AZ91D magnesium alloy sample good for pre-treatment as body material, be used as the negative electrode in deposition process and connect the negative electrode of pulse power equipment, Ni-Cr electrode is connected on deposition-gun as anode, rotate after energising, regulate processing parameter: under rated output 1500W, setting deposition voltage is 90V; Frequency is 600Hz; Pulsewidth is 400 μ s; Dutycycle 15%; Argon flow amount is 15L/min, electrode rotary Speed Setting is 3500r/min, depositing time is 2min, during deposition, adjustment deposition-gun and matrix are to guarantee that whole surface of test piece all obtains coating, coat-thickness can be obtained the Ni-18Cr coating of about 20 μm, coatingsurface dense uniform, has good corrosion resistance.
Claims (5)
1. a technology method for novel raising corrosion stability of magnesium alloy energy, its processing step is:
Step one: magnesium alloy is carried out pre-treatment, pre-mill is polished successively with 500 to 2000 order sand paper and removes superficial oxidation layer, then put into acetone soln ultrasonic assistant cleaning 3-5min, dry up with cold wind by washed with de-ionized water, put into moisture eliminator with for subsequent use.
Step 2: select Ni, Cr pure metal (purity: 99.99at%) and (wherein Cr content is 18at.% by non-consumable arc melting method acquisition Ni-18Cr electrode bar, atomic ratio), then, after annealing 24 hours in 850 DEG C of argon gas, take out as rotating electrode.Adopt 200 order sand paperings to remove zone of oxidation to light to the surface treatment of depositing electrode, then put into acetone soln ultrasonic cleaning 3-5min, dry up with cold wind by washed with de-ionized water after taking-up.
Step 3: differential of the arc alloying technology process prepares the process adjustments of Ni-Cr alloy layer: setting deposition voltage is 70-90V; Frequency is 400-600Hz; Pulsewidth is 200-400 μ s; Dutycycle: 5-15%; Power is 1500W.Controlling rotating electrode rotating speed is 1500-3500r/min, and gas flow argon flow amount is under the protection of 10-15L/min.At Mg alloy surface deposition 2min, can obtain a layer thickness on surface the Ni-Cr coating of 20-40 μm, coating uniform is fine and close and bonding strength is high.
2. according to the technological method of a kind of novel raising corrosion stability of magnesium alloy energy described in claims 1, it is characterized in that the surface preparation of described magnesium alloy is: with 500 to 2000 order sand paper, magnesium alloy is polished successively on pre-mill, then put into acetone soln ultrasonic assistant cleaning 3-5min, dry up with cold wind with deionized water rinsing.
3., according to the technological method of a kind of novel raising corrosion stability of magnesium alloy energy described in claims 1, what it is characterized in that described rotating electrode employing is Ni-Cr alloy, and its preparation process is: select Ni, Cr pure metal, its purity is: 99.99at%.The alloy ratio (wherein Cr content is 18at.%, atomic ratio) of good Ni and the Cr of proportioning, obtains Ni-18Cr electrode bar by non-consumable arc melting method, after then annealing 24 hours in 850 DEG C of argon gas, takes out as rotating electrode.Adopt 200 order sand paperings to remove zone of oxidation to light to the surface treatment of depositing electrode, then put into acetone soln ultrasonic cleaning 3-5min, dry up with cold wind by washed with de-ionized water after taking-up.Described Ni-Cr electrode diameter is Φ 1-5mm, and length is 20-100mm.
4. according to the technological method of a kind of novel raising corrosion stability of magnesium alloy energy described in claims 1, it is characterized in that described differential of the arc alloying technology parameter is: deposition power supply selects unidirectional pulse power supply, and first designing specified deposition power is depositing time 2min under 1500W prerequisite: setting deposition voltage is 70-90V; Electric current pulsewidth is 200-400 μ s; Frequency is 400-600Hz; Electrode rotary speed is 1500-3500r/min, dutycycle: 5-15%.Obtainable coat-thickness is the Ni-Cr coating of 20-40 μm.
5., according to the technological method of a kind of novel raising corrosion stability of magnesium alloy energy described in claims 1, it is characterized in that described protective gas is argon gas, its purity is greater than 99%, and work output is 10-15L/min.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109321785A (en) * | 2018-12-12 | 2019-02-12 | 常州大学 | A method of cobalt-based coating is prepared on cobalt-base alloys surface |
| CN114107904A (en) * | 2020-08-25 | 2022-03-01 | 荣耀终端有限公司 | Preparation method of structural member, structural member and electronic equipment |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102677014A (en) * | 2012-05-29 | 2012-09-19 | 重庆理工大学 | Modification method for alloying surface of magnesium alloy |
| CN104694926A (en) * | 2014-12-09 | 2015-06-10 | 常州大学 | Process method for preparing NiCr wear-resistant coating on copper surface |
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2015
- 2015-07-06 CN CN201510391803.9A patent/CN104962911A/en active Pending
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102677014A (en) * | 2012-05-29 | 2012-09-19 | 重庆理工大学 | Modification method for alloying surface of magnesium alloy |
| CN104694926A (en) * | 2014-12-09 | 2015-06-10 | 常州大学 | Process method for preparing NiCr wear-resistant coating on copper surface |
Non-Patent Citations (1)
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| 高玉新 等: ""电火花沉积Ni-Cr合金涂层的组织及性能"", 《材料工程》 * |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109321785A (en) * | 2018-12-12 | 2019-02-12 | 常州大学 | A method of cobalt-based coating is prepared on cobalt-base alloys surface |
| CN114107904A (en) * | 2020-08-25 | 2022-03-01 | 荣耀终端有限公司 | Preparation method of structural member, structural member and electronic equipment |
| CN114107904B (en) * | 2020-08-25 | 2024-03-12 | 荣耀终端有限公司 | Manufacturing method of structural part, structural part and electronic equipment |
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