1. What types of coating technology can be divided into?
(1) Vacuum coating (2) Electroplating (3) Chemical reaction (4) Heat treatment (5) Physical or mechanical treatment
2. What are the applications of plasma technology in surface technology?
- Sputter deposition: Sputtering is the use of high-speed ions to strike a solid sputter target, causing surface molecules to splash off and projecting onto the substrate to form a thin film. The initial kinetic energy of the sputtered ions is about 100 eV. A common plasma gas is argon.
- Plasma-assisted deposition: The chemical reaction of vapor-phase chemical deposition is carried out on a high-temperature substrate in order to obtain a sufficient energy response of the gas precursor.
- Plasma polymerization: The simplest coating technique for a polymer or plastic film is to apply it to a solvent and then apply it to a substrate. The plasma polymerization coating method excites molecular monomers into a plasma, and after a chemical reaction, forms a uniform polymer and is coated on the substrate. Since the substrate is impacted by the plasma, the adhesion is also strong.
- Plasma etching: Wet Alkaline Etching, which is the simplest and cheapest method, has the disadvantage that the alkaline etching has a crystal plane orientation and causes undercut problems.
- Plasma spray: Metal components that operate at high temperatures must be covered with ceramics to prevent high-temperature corrosion.
3. What are the heating methods for evaporation? What are their characteristics?
Heating methods are: (1) resistance heating (2) induction heating (3) electron beam heating (4) laser heating (5) arc heating.
Their respective characteristics:
(1) Resistance heating: This is the simplest heating method, and it is an advantage that the equipment is cheap and easy to operate.
(2) Induction heating: This method has good heating efficiency, rapid heating, and can heat large capacity.
(3) Electron beam heating: This heating method is to apply high-energy electrons of several thousand eV, which are focused by a magnetic field and directly hit by evaporating materials, and the temperature can be as high as 30,00℃. The source of its electrons is two: hot electrons generated by high temperature metals, and the other source of electrons is hollow cathode discharge.
(4) Laser heating: The laser beam can be optically focused on the evaporation source to generate a local instantaneous high temperature to escape. The earliest used is the pulse red laser, and then developed the ultraviolet excimer laser. The advantage of ultraviolet light is that the energy of each photon is much higher than that of infrared light, so the power density of the excimer laser is very high, and the function of heating the vapor deposition is similar to that of the electron beam. Often used to coat complex compounds, the quality of the coating is very good.
It is fundamentally different from the process of electron beam heating or sputtering. The excimer laser is detached from fine particles, and the latter is detached in molecular form.
(5) Arc heating: The advantages of cathodic arc deposition are:
a, the evaporation rate is fast, up to 1.0 micron per second
b, the substrate does not need to be heated
c, can be plated with high temperature metals and ceramic compounds
d, the coating is dense and the adhesion is good
4. Which industries can vacuum coating be applied to?
(1) The anti-reflective coating of lenses (MgO, MgF2, SiO2, etc.).
(2) Metal, alloy or compound coating, applied to microelectronics as wire, resistor, photoelectric function and other purposes.
(3) Aluminized or enamel-insulated as the electrode of the capacitor.
(4) Special alloy coating MCrAlY has heat resistance and oxidation resistance, temperature resistance up to 1100 °C, and can be applied to workpieces that are resistant to high-temperature environments, such as high-speed cutting and forming, turbine engine blades, etc.
(5) Metal plating on glass plates for decoration of buildings and UV protection.
(6) Ion-vapor deposition of aluminum, which is applied to the object to be plated with a negative high voltage, and then the aluminum is heated and evaporated, and the vapor is ionized by electron impact and then plated onto the steel plate.
(7) Aluminized on the film for decoration or labeling, and the coating has a metallic feel. The biggest use is packaging, which can prevent moisture and air from penetrating.
(8) Mechanical parts or knife-hardened hard-coated films (TiC, TiN, Al2O3) These super-hard films not only have high hardness, but also can effectively improve wear resistance, and the required thickness is small, which can meet the requirements of high precision of workpieces.
(9) Manufacture of special alloy flakes.
(10) A multilayer film is applied to the steel sheet to improve its performance.
(11) Silicon plating on CdS solar cells can increase their efficiency.
(12) The manufacture of nanopowder is plated on a cold substrate so that it does not adhere.
5. What are the characteristics of TiN titanium nitride coating?
(2) With a beautiful appearance
(3) It can be used for surgical and food utensils with safety.
(4) It has a lubricating effect and can reduce friction.
(5) With anti-corrosion function
(6) Can withstand high temperatures
6. What are the characteristics of a good film? What are the factors that influence it?
A good film is generally defined as its application function does not fail under normal conditions. In order to achieve this goal, in general, this film must have strong adhesion, low internal stress, low pinhole density, strong mechanical properties, uniform film thickness, and sufficient chemical resistance. . The properties of the film are mainly affected by the deposition process, film formation conditions, formation of the interface layer and the substrate, and subsequent heat treatment also plays an important role.
7. What are the basic characteristics of the film to have good adhesion?
(1) There must be strong chemical bonding between the atoms in the interface layer. It is preferable to have the formation or chemical adsorption of the compound.
(2) Low residual stress, which may be caused by the mismatch of the lattice and thermal expansion coefficient of the coating and the substrate, or the presence of impurities or poor structures in the film itself.
(3) There is no easily deformed surface structure, such as a fault structure, and a mechanically rough surface can reduce the deterioration of the problem.
(4) There is no problem of long-term deterioration. The coating is exposed to the external environment such as the atmosphere. If there is no chemical reaction such as oxidation, the coating naturally loses its function.
8. What are the measurement methods for film thickness?
It can be roughly divided into two types: in-situ measurement and off-site measurement.
In-situ measurement refers to the medium measurement of the coating, which is commonly used in physical vapor deposition, such as microbalance, optical, and electrical resistance measurement.
The off-site measurement refers to the measurement after the coating is completed, and the exercise of the plating film is relatively common, and has the purpose of understanding the plating efficiency, such as mass, profile meter, and scanning electron microscope.
9. What is the physical evaporation?
Physical vapor deposition is the process of volatilizing a substance and then depositing it on a predetermined substrate. Since the evaporation source has to be heated and volatilized and is carried out in a vacuum, it is also called thermal evaporation or vacuum evaporation.
It can be divided into three steps：
(1) The condensed matter is heated and volatilized into a vapor phase
(2) The steam moves in the air for a distance to the substrate
(3) The steam is cooled and condensed into a film on the substrate.
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