The surface metallization of nonmetallic materials adopts some kind of surface processor.
Art, forming a metal layer on the nonmetal surface, thus realizing resistance.
The purpose of grinding, anticorrosion and decoration endows nonmetallic materials with some new functions.
Use performance.
Surface metallization of nonmetallic materials is an important task to develop new materials.
The fields to be studied, such as the development and research of some superhard materials, will
Surface metallization technology of nonmetallic materials.
Surface metallization of nonmetallic materials has a long history in China.
Since China invented alchemy in ancient times, some skilled craftsmen have known to put
Gold is made by sticking gold foil as thin as cicada's wings on nonmetallic surfaces.
That's great. In some ancient temples, there are gods who cultivate themselves with golden faces.
Like a masterpiece of surface metallization of nonmetallic materials. Ancient China
Gold plating technology is to plate gold dissolved in mercury on nonmetal.
The surface of the product can be polished with agate after mercury volatilizes, reaching gold.
Shiny effect. Some were unearthed abroad, Cairo and Baghdad.
There are records of ceramic surface metallization in cultural relics. With modern science
With the development of science and technology, the method of depositing metal on the surface of nonmetallic materials
There are many methods, among which the main ones are metal powder spraying, vacuum coating and sputtering.
Spraying, electroless plating and electroplating, etc.
1 surface metallization of nonmetallic materials
As we all know, nonmetallic materials are mostly non-conductors, so it is necessary to make them non-gold.
Belonging to the metallization of material surface, its prerequisite must be to make its surface conductive.
As conductors, some metals deposited on nonmetallic surfaces can be used.
The method.
After the surface of nonmetallic materials is metallized, nonmetallic parts can be used instead.
Metal parts can save a lot of metal, simplify the processing technology and reduce the cost.
Make it have metallic luster, can conduct electricity, magnetism and welding, and can improve
Its mechanical properties and thermal stability. Make it not only have inherent nonmetal.
Properties, but also has some characteristics of metal materials, become a composite material.
Materials, thus expanding the scope of use of non-metallic materials.
Surface metallization of nonmetallic materials is an important part of materials science.
Components, research on new materials, development and application of new materials.
Domain has important practical significance. In addition, the surface of nonmetallic materials
After metallization, it has good corrosion resistance. In a humid environment, metals
There is no galvanic effect between this layer and nonmetallic matrix.
Non-metallic materials include organic materials (such as various plastics, fibers,
Resin) and inorganic materials (mainly various ceramics, glass, single crystal materials
Wait). The bonding force between these materials and the metal layer covered on their surfaces.
Very weak, the influence of its outer surface is more prominent, that is,
It is said that the bonding strength between these materials and the metal coating is low, in order to
Improve the adhesion between substrate and coating, and improve the adhesion between metal and nonmetal surface.
Before chemical treatment, its surface must be treated to obtain an ideal surface shape.
And increase its wettability. In addition, a matrix of nonmetallic materials is given.
Some processes of surface catalytic activity will affect its metallization layer.
Binding force. There are many kinds of nonmetallic materials, only for new projects.
As far as matter is concerned, it is endless and its physical and chemical properties are different.
No, some are very different. Such as for plastic demoulding.
Release agent, the use of each factory is different, which makes it duplicitous.
The surface treatment technology will be different. Therefore, the surface of nonmetallic materials is studied.
The pretreatment technology and metallization process of metallization can obtain excellent performance.
The key to metallized surface.
2 surface metallization process of nonmetallic materials
Most nonmetallic materials are poor conductors of electricity and heat.
Before plating metal on the surface of materials, it is usually necessary to make non-metallic materials first.
The surface becomes a conductor, and it is possible to realize metal by covering it with a metal film.
Change.
There are many ways to form metal films, such as coating conductive adhesive and silver paste.
High temperature reduction method, chemical coating method and metal powder spraying method. special
Which method is adopted depends on the material and application.
The surface metallization process of nonmetallic materials mainly includes pretreatment process.
And a method for obtaining the metal layer.
2. 1 Pretreatment process
2. 1. 1 Eliminating internal stress
The internal stress produced by plastic molding must be eliminated first. Ordinary mining
The internal stress can be eliminated by heat treatment or leached by glacial acetic acid.
Impregnation method or organic solvent impregnation method to eliminate internal stress.
2. 1.2 surface roughening
The surface of nonmetallic materials is made by manual, mechanical or chemical methods.
The process of becoming rough and dull is called roughening. Coarsening can improve the table
Surface hydrophilicity and roughness, to ensure that the metal layer has a good
Adhesion.
There are two kinds of roughening methods: mechanical roughening and chemical roughening, which should be based on
Determination of size, shape, quantity and physical and chemical properties of nonmetallic materials
Use one or more roughening methods.
Mechanical roughening is carried out by rolling, sandblasting or sanding.
Remove its burr and increase its surface area, thus improving the bonding force of the metal layer.
Force.
Chemical roughening is to change the surface of nonmetallic materials with chemical etchant.
Rough, increase the surface area and generate some polar groups, so that its surface
From hydrophobicity to hydrophilicity. Chemical roughening is widely used at present.
First, different chemical methods should be adopted for different nonmetallic materials.
Study on coarsening solution and process specification. Used for plastic coarsening, high chromium acid type
The coarsening liquid is widely used. This coarsening liquid has fast coarsening speed and good effect.
All right. Its reference formula and application conditions are as follows: chromic anhydride (CrO3)400~
430 g/L; Concentrated sulfuric acid180 ~ 220 ml/l; The temperature is 60-70 DEG C; time
10 ~ 30 minutes.
In order to remove residues on the surface of materials during chemical roughening
Cr6+ cleaning requires neutralization in 10% ammonia water and neutralization in.
1%~5% sodium sulfite solution for reduction.
2. 1.3 degreasing
Because the surface of the material will be damaged by oil, organic solvent or
Chemical degreasing, roughening and degreasing processes can be reversed, but
Before proceeding to the next process, the oil stain must be thoroughly removed.
2. 1.4 sensitization
It is easy to adsorb a layer on rough and degreased clean surfaces.
In the oxidation of metal ions, it is a reducing agent for coating metals.
In the electroplating process, metal ions in the solution are easily deposited on it.
On the surface of the workpiece, this process is called sensitization. Reference of sensitized solution
The formula and process are as follows: stannous chloride10 ~100g/l; Hydrochloric acid 10~
50 ml/l; 1 metal tin bar; Temperature18 ~ 25℃; 3 minutes is fast.
The pH value of chemical solution should be controlled between 0.5~ 1.9.
2. 1.5 activation
Depositing metal with catalytic activity on the sensitized workpiece surface.
Layer, this process is called activation. The purpose of activation is for the next step.
Electroless plating provides a crystallization center and improves the deposition speed and uniformity of the coating.
Consistency.
At present, the widely used activating solutions are silver nitrate activating solution and chlorination method.
Palladium activation solution. The former is an alkaline solution, mainly composed of silver nitrate and
Made of ammonia water; The latter is acidic and alkaline, but it is more commonly used.
It is an acidic activating solution, which has a short induction time in the process of electroless plating, leading to the formation of deposits.
Good synergy.
The common formula and process of silver nitrate activating solution are as follows: silver nitrate 2.
~ 5g/L； Ammonia (25%) 20 ~ 25ml/L; Temperature15 ~ 25℃; time
1~5min。
Distilled water must be used in preparation, otherwise silver ions and water will be mixed.
Chloride ions will generate silver chloride precipitate, which will reduce the silver content.
2.2 Method of Obtaining Metal Layer
Depending on different materials, there are many ways to obtain a metal layer.
Selection of reference related monographs. Commonly used methods are electroless plating and electroplating.
The electroless plating process is introduced here. Electroless plating, also known as electroless plating, is
In the absence of current, with the help of reducing agent, oxidation occurs in the same solution.
Reduction reaction, so that metal ions are reduced and deposited on the workpiece surface.
Electroplating on the substrate is a controllable method to deposit metal.
Automatic catalytic chemical reduction process.
After coarsening, sensitization and activation, the surface of the workpiece is densely covered with accelerant.
Chemical active center, when it is immersed in electroless plating solution, the metal in the plating solution
The ions are reduced, deposited on the surface of the workpiece and charged.
The converted catalytic active center becomes a crystal reduced by metal ions.
After reduction, metal ions are first deposited in the active center, and then one by one.
Gradually expand to form a continuous metal layer with a certain thickness, not gold.
This is the end of the whole process of surface metallization of metal materials.
Electroless plating can be used for nickel, copper, cobalt, gold, silver and other metals, while electroless plating
Nickel is the fastest growing industry in electroless plating industry. It is famous for its excellence.
Performance, has been widely used in almost all industrial sectors,
It has created huge economic benefits, and it is still 5%~7% every year.
The speed is increasing.
The common formula and process of electroless nickel plating are as follows: nickel sulfate 25.
~ 30g/L； 20-25g/l of sodium hypophosphite; Sodium acetate15g/l; lemon
Sodium citrate10g/l; Additive 5g/l; A small amount of brightener; PH value 4.5
~5; The temperature is 85-90 DEG C..
Application of surface metallization of nonmetallic materials
3. 1 surface decoration
Signboards and unit names in front of some large commercial buildings are often invited.
The inscriptions of famous calligraphers are difficult to machine if they are made of metal.
It's difficult, but it's much easier to make it out of wood, plastic or cement.
Excellent results can be obtained by metal brush plating.
The names of some large memorial halls and the titles of each part.
It is shown in bold type and can be cut with plastic plate.
However, the required gold is made by chemical deposition or brush plating.
It is a color, which can play the role of confusing the fake with the real.
There are various handicrafts on the market now, such as Wan Li Great Wall and Oolong.
Play with beads, Guanyin bodhisattva, Sakyamuni statue, etc. Are coated with nonmetal.
Produced by, quite popular with Chinese and foreign guests, becoming a social interaction.
High-end gifts.
3.2 Improve the wear resistance of nonmetallic materials
Non-metallic materials have the advantages of light weight and easy processing. But they do exist.
The surface lacks luster, wear resistance and other shortcomings. For example, some household appliances.
The parts of instruments and equipment can be made of plastic and then placed on its surface.
Coating a metal coating can not only improve the metallic luster, but also improve it.
Wear resistance.
3.3 Manufacturing superhard materials
As we all know, both synthetic diamond and cubic boron carbide are artificially synthesized.
A hard material, if the chemical plating method is adopted, is coated on it.
A hard and wear-resistant coating was obtained by plating a layer of Ni-P alloy on the surface.
A new superhard material with high hardness.
3.4 Ceramic Metallization
Engineering ceramics have high hardness, good corrosion resistance and dielectric properties.
Many advantages. Especially in recent years, the appearance of nano-ceramics has become
A striking new engineering material. However, ceramics do not.
Conductivity, toughness and weldability, therefore, when using ceramics, it is often necessary to advance.
Metallization treatment of line surface. Because there are many holes on the ceramic surface
Gap, before metallization, ceramic surface should be sealed with resin.
Hole treatment to prevent the treatment liquid from entering, followed by a series of rough machining.
Chemical treatment, sensitization and activation treatment are carried out to obtain a platable surface with catalytic activity.
Surface, and then thickening the surface coating by electroless plating or electroplating.
In order to meet the requirements of users, the ceramic adopts metal surface.
3.5 Change the solderability of nonmetals
Some parts of electronic equipment, in order to save metal materials, reduce
Lightweight or simplify the production process, often using plastic production, and then use.
Non-metallic electroplating or electroless plating process, so that its surface becomes a conductive layer, on the
Overcomes the defect that plastic parts cannot be welded.
3.6 Make nonmetallic materials conductive.
Most nonmetallic materials are insulators in order to make them locally conductive.
Both electric and non-metallic brush plating technologies can be used. Such as a large number of printed electricity.
Electroplated plate, when the plate is partially broken, nonmetallic brush plating can be used.
Make repairs. Plastic casing of electronic instrument, such as inner wall electroplating.
The last metal coating can be formed by using the conductivity of the metal coating.
Good shielding effect can prevent the external electromagnetic field from drying the instrument.
Excuse me.
3.7 Make nonmetallic materials have magnetic conductivity.
Non-metallic materials themselves have no magnetic conductivity, if they are on plastic.
Plating a layer of magnetic material such as nickel cobalt or nickel-iron alloy can be used as electrons.
Magnetic storage element in computer.
3.8 Improve anti-aging ability
Some plastics have poor light and heat resistance and are easily exposed to sunlight.
Aging, such as plating a metal coating on its surface, can improve its resistance.
Aging ability, prolong its service life.
Development and display of surface metallization of nonmetallic materials
look
Surface metallization of nonmetallic materials is an important subject in materials science.
Major areas. Many scholars at home and abroad are devoted to this research.
It is the research direction of developing new materials, which develops rapidly and has a very broad prospect.
Vast
Pretreatment technology is the key to surface metallization of nonmetallic materials.
Sensitization and activation are the main research contents of pretreatment technology.
At present, various colloidal activators have been developed and commercialized. ask
Strengthen the study of activation mechanism and guide practice with theory.
Electroless plating is usually used for surface metallization of nonmetallic materials.
The formula of electroless plating solution is the core of this technology.
Stability is the key, and multi-element complexation should be adopted to increase the stability of plating solution.
Sex, but also to strengthen the research of brightener, improve the appearance effect of plated parts.
Surface metallization of nonmetallic materials has a good market prospect and social demand.
Large, relying on this technology to develop new products will gain a good society.
Economic benefits.
5 conclusion
Surface metallization of nonmetallic materials is a pretreatment technology and the preparation of gold.
Belonging to the product of layer combination, there are many methods, principles, materials, processes and
Different equipment, according to different matrix materials and different process requirements.
Choose different surface metallization methods.
Surface metallization of nonmetallic materials is an important part of new material research.
It will be very good to develop new materials related to this.
Social and economic benefits.
References:
[1] Jiang Xiaoxia, Shen Wei. Theory and practice of electroless plating [M]. Beijing: International Industry Association.
Press, 2000.237-24 1.
[2] Zhang Yuncheng, Hu Runan,. Electroplating manual. The first volume [M]. Beijing: International workers.
Industry Press, 2000.607-685.
Chunhua Lin, Ge Xiangrong. Brief introduction of brush plating technology [M]. Beijing: Machinery industry.
Press,1991.205-212.