Equipment for the deposition of thin-film coatings of diamond-like amorphous carbon (DLC)

Diamond-like carbon (DLC) is a metastable form of amorphous carbon containing a significant amount of sp3 bonds. It has high mechanical hardness, is chemically inert, optically transparent, and is a wide band gap semiconductor. DLC thin-film coatings are widely used as protective coatings in the automotive industry, the manufacture of cutting tools, the manufacture of micro-electromechanical devices, the manufacture of optical devices (IR region of the spectrum of optical radiation), etc.

For the deposition of thin-film hardening coatings, various methods are currently used, conditionally divided into two groups - chemical vapor deposition (CVD) and physical vapor deposition (PVD). The used methods have limitations in their application due to the physical properties of the substrates, as well as limitations associated with the physical properties of the resulting thin-film coatings. These limitations, as well as the cost of implementing one or another method, determine a large number of options for technological systems for the deposition of DLC coatings currently used in industry.

LLC "Nanotechnovac" offers to the consumer elements for building a technological complex for the deposition of thin-film coatings of tetrahedral amorphous carbon using PVD methods of their deposition. The vapor phase in the technological system is the carbon plasma of a pulsed vacuum electric arc discharge

A pulsed carbon plasma generator consists of an anode, a cathode, an additional anode, and a system of initiating electrodes. All electrodes of the plasma generator are made of dense finely dispersed graphite. The system of initiating electrodes consists of a grounded (base) electrode and one or more (three in the figure) initiating electrodes which separated by a ceramic insulator. Plasma is generated by a pulsed arc discharge between the cathode and the anode of the generator.

This discharge is supplied by the electrical energy stored in the capacitive accumulator. For the development of a pulsed discharge, it is necessary to create certain potential differences between the generator electrodes first, as well as to provide a sufficient supply of energy to support the development of the main discharge. Energy is accumulated in the capacitor unit, where, in addition to the capacitive accumulator, additional capacitors of the additional anode and voltage boost circuits are located.

The capacitors of the capacitor bank are charged to the required voltages by the power supply and system control unit. The control and power supply unit for the electric arc carbon plasma source provides power to the pulsed electric arc evaporator equipped with a capacitive energy storage with an electric capacity of up to 2200 μF. The power source provides charging of the storage up to the set voltage, power supply of the additional anode capacitor bank and supply of the potential to the ignition electrode, which provides the initiating discharge. The power supply provides control of the pulsed electric arc evaporator by determining the repetition rate of the discharge pulses, the number of discharge pulses in the current cycle, controlling the number and ratio of the number of discharge initiation pulses (ignition pulses) and storage discharge pulses.

The described technological system makes it possible to apply thin-film DLC coatings based on hydrogen-free films of tetrahedral amorphous carbon. Samples with the following characteristics were obtained depending on the type of substrate and process parameters:

Density 2.9 g/cm3
Microhardness 35-65 GPa
Young’s module 700 GPa
sp3 concentration 30-80 %
Friction coefficient 0.1-0.12