Etching processing method of magnesium and alloys

The etching processing methods of magnesium and alloys are as follows:

Mg is a very active metal and can react with a variety of acids. Among them, the corrosive solution based on H2S04 is easier to control and has been widely used in chemical etching of aviation parts. The reaction formula is as follows:

Mg H2 S04~ M python 04 H2t (5-78)

In theory, according to the reaction (5-78), 4 g H2 S04 is required for every 1 g of Mg etched. However, in fact, 17g HI S04 is required for each lgMg etching, which is the same as the chemical etching solution for etching aluminum. In order to reduce the content of MgS04 in the etching solution, it is necessary to discharge part of the bath liquid, which will lose a large amount of H2SO4.

When H2S04 is used alone as an etchant, the etching rate can be better controlled by adding a corrosion inhibitor, and a lower surface roughness can be obtained to form a better fillet. Nat SO4, sodium citrate and wetting agent constitute a suitable corrosion inhibitor, which is added to H2SO. In the chemical etching solution, it is easy to obtain key effects such as smooth surface and uniform etching rate when using this etching solution for chemical etching.

Changes in temperature can significantly change the etching rate, so in actual production, the etching rate can be controlled by changing the etching temperature.

Chemical etching of Mg is a strongly exothermic reaction. Dissolving 1g mg in H2 Sad will release the heat of 19562.4), while the heat released by the corrosion of the same amount of Al in NaOH is 16243.48j,, Mg has worse thermal conductivity than Al, therefore, the chemical control of Mg Etching is more difficult than controlled chemical etching of Al, which must be done at lower temperatures. At the same time, the temperature of the corrosive solution and the concentration of H2S04 must be carefully controlled to avoid rough surfaces and other abnormalities.

In addition to using H2 S04 for chemical etching of Mg, HNO, or H3 P04 can be used as etchants for chemical etching.

Explanation of related terms

etching

The etching commonly referred to is also called photochemical etching, which refers to the removal of the protective film in the area to be etched after exposure to plate making and development, and contact with chemical solutions during etching to achieve the effect of dissolution and corrosion, forming concave-convex or hollow molding. It can be used to manufacture copper plate, zinc plate and other printing embossing plates at the earliest, and it is also widely used in the processing of weight reduction instrument panels, nameplates and thin workpieces that are difficult to be processed by traditional processing methods; through continuous improvement and process equipment It can also be used for the processing of precision etching products of electronic sheet parts in the aviation, machinery and chemical industries, especially in the semiconductor process, etching is an indispensable technology.

Mg

The top left is the MG car logo, the top right is a 1955 MG sports car, the bottom left is a 1930 MG sports car, and the bottom right is a 1955 MG sports car.

corrosion

Metal materials and structures made of them, in the natural environment or under working conditions, are deteriorated and destroyed due to chemical or electrochemical action with the environmental medium in which they are located. This phenomenon is called corrosion, which is also known as corrosion. Including the combined action of the above factors and mechanical factors or biological factors. Some physical effects such as the physical dissolution of metal materials in some liquid metals can also be classified into the category of metal corrosion. In general, rusting refers specifically to steel and iron-based alloys, which, under the action of oxygen and water, form rust, a corrosion product mainly composed of hydrous iron oxide. Non-ferrous metals and their alloys can corrode but do not rust, but instead form corrosion products similar to rust, such as patina on copper and copper alloys, occasionally referred to as patina. There are some other forms of definitions for corrosion and metal corrosion. Metal corrosion can also be said to be the reverse process of the smelting process because metals and alloys are corroded and return to the compound state of ore. The above definitions apply not only to metallic materials, but also to non-metallic materials such as plastics, ceramics, concrete and wood in a broad sense. For example, the deterioration of paints and rubbers due to sunlight or chemicals, the melting of steelmaking furnace linings, and the corrosion of one metal by the molten liquid metal of another are the results of processes that fall under the category of material corrosion, which is a broad definition. . Metals and their alloys are still recognized today as the most important structural materials, so metal corrosion naturally becomes one of the most interesting problems. There are many forms of corrosion damage, and the causes of metal corrosion under different environmental conditions are not the same, and the influencing factors are also very complex. In order to prevent and slow down the corrosion damage and its damage, the corrosion process is blocked and controlled by changing some action conditions and influencing factors. The methods, technologies and corresponding engineering implementations thus developed become anti-corrosion engineering technologies.