TWI405871B - Chemical Treatment of Magnesium - Li Alloy - Google Patents

Abstract

A chemical conversion coating method for magnesium-lithium alloy can produce protective coatings with metallic luster over a surface of the magnesium-lithium alloy, and comprises a degreasing step of removing oil stain over the surface of the magnesium-lithium alloy; a water rinsing step of cleaning the residual degreaser; an acid pickling step of performing surface activation treatment through a pickling agent containing nitric acid and acetic acid; a water rinsing step of cleaning the residual pickling agent; a stain removing step of removing the stains on the surface; a water rinsing step of cleaning the residual stain-removing agent; a passivation step of performing passivation treatment for the surface of the magnesium-lithium alloy to form a protection layer through a passivator; a water rinsing step of cleaning the residual passivatior, and a baking step of finally completing the surface chemical conversion coating of the magnesium-lithium alloy.

Description

Method for forming magnesium magnesium alloy

The present invention relates to a surface treatment method for a magnesium-lithium alloy, and more particularly to a chemical conversion coating method for a magnesium-lithium alloy, which can exhibit a metallic luster on a surface of a magnesium-lithium alloy.

Magnesium-aluminum alloy has high rigidity and light weight (specific gravity 1.74, only 2/3 of aluminum, 1/4 of iron), good heat dissipation and electromagnetic shielding, and is very suitable for the manufacture of 3C products. On the other hand, magnesium is the third largest element in seawater, and the source of raw materials is sufficient, which is also in line with the requirements of industrial mass production. Magnesium can be made into various magnesium alloys by adding different elements such as aluminum (Al), Mn (Mn) and zinc (Zn), and is widely used in the manufacture of many industrial products, such as notebook computer casings, bicycles. The body structure and other aspects. Magnesium-lithium alloy (Mg-Li alloy) is an alloy composed of metal lithium added to the base of magnesium. It generally contains more than 6~7% of lithium and has a density of 1.14~1.57g/cm ³ , which is the lightest structural material at present. The strength is higher than the general magnesium alloy. Since the activity of lithium is higher than that of magnesium, the production of magnesium-lithium alloy is relatively difficult, and the manufacturing technology of magnesium-lithium alloy is continuously developed, which makes the feasibility of using magnesium-lithium alloy for manufacturing industrial products greatly improved.

Although many surface treatment techniques for magnesium alloys have been proposed, surface treatment techniques for magnesium-lithium alloys are still limited, and surface treatment techniques for magnesium-lithium alloys are known to focus on the formation of passivation layers, for example, as disclosed. Chinese invention patent CN101245485 "A method for surface treatment of magnesium-lithium alloy" is applied to the surface treatment of magnesium-lithium alloy by micro-arc oxidation technology to form a ceramic oxide film with good corrosion resistance.

Since most industrial products have a certain degree of need for the gloss of the surface of metal materials, how to improve the gloss of the surface of magnesium-lithium alloy while producing a film on the surface of magnesium-lithium alloy material remains to be studied and developed. .

The invention provides a method for forming a magnesium-lithium alloy (LZ91), which can improve the gloss effect of the surface of the magnesium-lithium alloy while producing a film on the surface of the magnesium-lithium alloy material.

An embodiment of the method of the present invention comprises: a degreasing step; a water washing step; a pickling step, a surface activation treatment with an acid pickling agent containing nitric acid and acetic acid; a water washing step; a spot removing step; a water washing step; a passivation step; and a water washing step ; and baking steps.

The pickling step in the method of the present invention removes the oxide on the surface of the magnesium-lithium alloy by using an aqueous solution containing nitric acid or acetic acid as an acid pickling agent, thereby improving the surface gloss effect of the magnesium-lithium alloy.

Regarding the detailed technical contents of the present invention and the effects thereof, the following description will be made in conjunction with the drawings.

An embodiment of the method of the present invention, as shown in "Figure 1," includes:

A. Degreasing step, removing the oil stain on the surface with a degreasing agent;

B. a water washing step for cleaning the residual degreaser;

C. pickling step, using an aqueous solution containing nitric acid and acetic acid as an acid pickling agent to perform surface activation treatment on the magnesium-lithium alloy;

D. a water washing step for cleaning the residual pickling agent;

E. removing the spot by removing the spot on the surface of the magnesium-lithium alloy with a stain removing agent;

F. a water washing step for cleaning the residual stain removing agent;

G. passivation step, passivating the surface of the magnesium-lithium alloy with a passivating agent to produce a chemical coating (Protective coatings);

H. a water washing step for cleaning residual passivating agent;

I. Baking step, thereby completing the formation treatment of the magnesium-lithium alloy.

In the degreasing step of step A, a degreasing agent generally suitable for magnesium-lithium alloy, such as a degreasing agent produced by Jasco, may be used, and the degreasing treatment is carried out for 5-10 minutes at a concentration of 30-60 g/L and a temperature of 60-80 ° C. Used to remove oil stains on the surface of magnesium-lithium alloys.

As for the above several washing steps, all of them are washed with pure water at room temperature for 1-2 minutes.

The aqueous pickling agent used in the step C contains a weight ratio of 0.5 to 3% of nitric acid, 0.3 to 1% of acetic acid, 1 to 5% of an oxidizing agent, and 0.3 to 1% of a neutralizing agent . In the pickling step, an acid pickling agent containing the above components is used for pickling treatment at room temperature for 1-3 minutes to remove oxides on the surface of the magnesium-lithium alloy.

In the step of removing the spot of step E, a spot removing agent generally suitable for magnesium-lithium alloy, for example, a spot removing agent produced by Jasco, may be used, and the concentration is 100-300 ml/L, and the temperature is 60-80 ° C for 3-8 minutes. Despot removal treatment to remove spots on the surface of magnesium-lithium alloy.

The passivation step of step G can be carried out by using a spot removing agent suitable for a magnesium-lithium alloy, such as a JCB passivating agent, wherein the J agent of the JCB passivating agent has a concentration of 40 ml/L and the concentration of the B agent is 10 ml/L. The pH value is adjusted to 3.0 to 5.0 (pH), and the passivation treatment is performed at a temperature of 60-80 ° C for 1-5 minutes to further form a film on the surface of the magnesium-lithium alloy.

The baking step of the step I is a baking treatment of the magnesium-lithium alloy for 30 minutes at a temperature of 80-100 ° C.

The above embodiment of the method of the present invention is described in which the processing conditions of the respective steps can also refer to the contents of Table 1 below.

Another embodiment of the method of the present invention may be based on the steps of the embodiment of the above "Fig. 1", except that the pickling agent used in the pickling step and the processing conditions thereof are mainly based on the detailed components herein, and the rest The step and the chemical conversion treatment agent used therefor can be carried out by using a surface treatment agent currently applied to a magnesium-lithium alloy as needed.

In summary, the method of the present invention can be applied to the surface treatment of a magnesium-lithium alloy material, which can produce a film on the surface of the magnesium-lithium alloy material while improving the gloss of the surface of the magnesium-lithium alloy.

While the present invention has been described above in the foregoing embodiments, it is not intended to limit the invention, and the invention may be modified and modified without departing from the spirit and scope of the invention. The scope of patent protection shall be subject to the definition of the scope of the patent application attached to this specification.

A. . . Degreasing step

B. . . Washing step

C. . . Pickling step

D. . . Washing step

E. . . Despeckle step

F. . . Washing step

G. . . Passivation step

H. . . Washing step

I. . . Baking step

Figure 1 is a flow chart showing the steps of an embodiment of the method of the present invention.

A. . . Degreasing step

B. . . Washing step

C. . . Pickling step

D. . . Washing step

E. . . Despeckle step

F. . . Washing step

G. . . Passivation step

H. . . Washing step

I. . . Baking step

Claims (5)

A method for chemically forming a magnesium-lithium alloy, comprising: A. a degreasing step, removing the oil stain on the surface of the magnesium-lithium alloy by a degreasing agent; B. a water washing step for cleaning the residual degreaser; C. a pickling step at a normal temperature The magnesium-lithium alloy is subjected to pickling treatment with an aqueous acid pickling solution for 1-3 minutes, and the aqueous pickling agent solution comprises 0.5 to 3% by weight of nitric acid, 0.3 to 1% of acetic acid, 1 to 5% of oxidizing agent and 0.3% by weight. ~1% of the wronging agent; D. Washing step to clean the residual pickling agent; E. Removing the spotting step, using the stain removing agent produced by Jasco Company at a concentration of 100-300 ml/L at a temperature of 60-80 °C, 3-8 minutes of speckle removal to remove the surface of the magnesium-lithium alloy; F. water washing step to clean the residual stain removing agent; G. passivation step, passivating agent to the magnesium-lithium alloy The surface is passivated to produce a chemical film; H. a water washing step for cleaning the residual passivating agent; and I. a baking step to complete the chemical conversion treatment of the magnesium lithium alloy. The method for chemically treating a magnesium-lithium alloy according to claim 1, wherein the degreasing step of the step A can be carried out by using a degreasing agent produced by Jasco, at a concentration of 30-60 g/L at a temperature of 60-80 ° C. Degreasing treatment for 5-10 minutes. The method for chemically treating a magnesium-lithium alloy according to claim 1, wherein the water washing steps of the steps B, D, F, and H are all washed with normal temperature pure water for 1-2 minutes. bell. The method for chemically forming a magnesium-lithium alloy according to claim 1, wherein the baking step of the step I is performed by baking the magnesium-lithium alloy at a temperature of 80-100 ° C for 30 minutes. A method for chemically forming a magnesium-lithium alloy, comprising: A. a degreasing step, removing the oil stain on the surface of the magnesium-lithium alloy by a degreasing agent; B. a water washing step for cleaning the residual degreaser; C. a pickling step at a normal temperature The magnesium-lithium alloy is subjected to pickling treatment with an aqueous acid pickling solution for 1-3 minutes, and the aqueous pickling agent solution comprises 0.5 to 3% by weight of nitric acid, 0.3 to 1% of acetic acid, 1 to 5% of oxidizing agent and 0.3% by weight. ~1% of a dissolving agent; D. a water washing step for cleaning the residual pickling agent; E. removing the spotting agent, removing the spot on the surface of the magnesium-lithium alloy with a stain removing agent; F. washing step for cleaning Residual the stain removing agent; G. passivation step, passivating the surface of the magnesium lithium alloy with a JCB passivating agent to produce a chemical conversion film, wherein the JBC passivating agent comprises a pH value of 3.0 to 5.0 (pH), and the concentration is 40 ml/L of the A agent and the concentration of 10 ml/L of the B agent, at a temperature of 60-80 ° C, for 1-5 minutes of the passivation treatment; H. a water washing step for cleaning the residual passivating agent; The baking step further completes the chemical conversion treatment of the magnesium-lithium alloy.