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INNOVATIVE TECHNOLOGY                                                                INNOVATIVE TECHNOLOGY

 and is carried out according to a given technological program. An observation window is mounted      Arc discharge
 in the water-cooled chamber for visual observation of the process.     It is important to note that most of the known plasma technologies are based on the use
    of an arc discharge (electric arc) as an energy source for conducting technological processes.
            Arc discharges are called discharges at a current density of 102 - 103 A / mm2 and a
    relatively low cathode potential drop of the order of the ionization and excitation potentials of
    the atoms of the gaseous medium or the evaporated metal. The small value of the cathodic
 Table 2.   potential drop is the result of the action of other mechanisms of cathodic electron emission than
 Properties of products and tools after plasma nitridin  in a glow discharge. They create a current density that allows the full discharge current to flow.
 Type of products and   steel  Layer thickness, mm  Surface hardness, HV
 tools
 Gear wheels,  450  0,3 – 0,4  450 – 600
 screws,  20 KH  0,3 – 0,5  450 – 600
 plungers,  40 KH  0,2 – 0,5  600 – 750
 Crankshafts and   40 KH МА  0,25 – 0,5  650 – 850
 camshafts,  18 KHGТ  0,25 – 0,5  650 – 750
 Augers,  38 KHМА  0,3 – 0,6  650 – 850
 Cylinders,  38 KHМFА  0,3 – 0,5  850 – 1100
 Axles,  38 KH2МYUА  0,2– 0,5  850 – 1250
 Bushings,  12 KH2N4L  0,2 – 0,5  650 – 720
 Liners  35 KHGSА  0,2 – 0,5  450 – 750
 38KHN3МFА  0,05 – 0,15  900 – 1250
 12KH18N10Т  0,05 – 0,2  900 – 1250
 Molds, matrices  5KHNМ  0,2 – 0,3  600 – 700  a   b                                      c
 5KHNМF  0,15 – 0,3  600 – 700
 3KH2V8  0,15 – 0,3  900 – 1100  Fig. 4. Plasma nitriding unit, working chamber diameter 350 mm, height 500 mm, power consumption 3 kW (a), type of
 4KH4VМFS  0,15 – 0,3  900 – 1150  products in a glow discharge in the process plasma nitriding (b).
 30KH3М3F  0,15 – 0,3  900 – 1100
 Dies, punches for deep   KH12  0,6 – 0,15  900 – 1100     Arc cathodes emit electrons as a result of thermionic, autoelectric and thermoautoelectronic
 drawing  KH12М  0,6 – 0,15  900 – 1100  emissions. Characteristic parameters of arc discharges: current 1 - 105 A, voltage from 20 - 30
 KH12МF  0,6 – 0,16  900 – 1100  V (short arcs) to kilovolts.
 Cutters, drills, taps,   R18  0,1 – 0,05  900 – 1200     The main types of arc discharges that are widely used for technological purposes are: at
 reamers, broaches,   R6М5  0,1 – 0,05  900 – 1200  low pressure, a discharge with a cold cathode and moving cathode spots (emission occurs from
 cutters  R9К10  0,1 – 0,05  900 – 1200
    constantly moving cathode spots with a current density of 104 - 107 A / cm2); at high pressure
    (0.1 - 1.0 atm) - dense low-temperature equilibrium plasma with an electron temperature of
    0.5 - 1.0 eV and higher.






    Table 3.
    The distinctive characteristics of this process in comparison with gas chemical thermal   Characteristics of the installation for microplasma treatment.
 treatment are:
    ● reduction of processing time by 2 - 5 times due to higher saturation rate;
    ● efficiency of the process by reducing the consumption of working gases 20 - 100 times;  Power consumption, kW  0,5
    ● increase in the utilization rate of electricity by reducing the consumption of electricity   Mains supply voltage, V  220
 by 1.5 - 3 times;  Limits of step current regulation, A                                      10 – 20
    ● possibility of high-quality processing of blind bores and through holes;  Working voltage, no more V  14
    ● simplicity and reliability of screen protection against nitriding of non-hardened surfaces;  Argon consumption, no more than l / min  1,5
    ●  insignificant  deformations  of  products  during  processing  and  changes  in  roughness
 parameters, lower temperatures;  Autonomous cooling system volume, l                         4
    ● obtaining a nitrided layer uniform in thickness on all product surfaces;  Overall dimensions of the microplasmatron, (diameter x length),   (8 – 16) х (50 –
    ● improvement of sanitary and hygienic conditions of production.  mm                      250)
    Table 2 shows certain types of products and tools, as well as surface properties after   Overall dimensions, mm  500х450х250х
 plasma nitriding.  Installation weight, kg                                                   25
    A promising direction for further increasing the wear resistance of parts processed using
 plasma nitriding is the subsequent deposition of thin-film tribological coatings using PVD and
 CVD processes. Currently, technologies and equipment have been developed for non-vacuum
 local chemical-thermal treatment of various products using saturated plasma jets and plasma
 arcs, for example, local plasma nitriding (Fig. 5), local plasma carburizing (Fig. 6).


 34  Stanochniy park                                                                            Stanochniy park      35
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