6 Morel, S., and Cuba ≈a, J.: Catalysing burn effect of rest CO and reduction emission NO x by ceramic coatings Proc.: Research Problems in Heating Energy, Warsaw, 8-10 December, 1993, p 235-242 69 Sulima, A.M., Sulov, V.A., and Yagodnitski, Yu.D.: Superficial layer and service properties of machine components (in Russian) Publ Masinostroenye, Moscow 1988 70 Kocañda, S., and Szala, J.: Fundamentals of fatigue calculations (in Polish) PWN, Warsaw, 1985 Katarzyñski, S., Kocañda, S., and Zakrzewski, M.: Research of mechanical properties of metals (in Polish) Edition III, WNT, Warsaw 1967 72 Dyl˙g, Z., and Or≈oœ, Z.: Fatigue strength of materials (in Polish) WNT, Warsaw, 1961 73 Joint Report: Metal fatigue (translation from English) WNT, Warsaw 1962 74 ISO R 373-1964 General principles for fatigue testing Przybylski, W.: Burnishing technology WNT, Warsaw 1987 76 Nakonieczny, A., and Szyrle, W.: Fatigue strength, residual stresses and microstructure of carburized and shot-peened layer (in Polish) Proc.: II Polish Conference Surface Treatment, 13-15 October, 1993, Kule/Czestochowa, pp 61-66 7 Gurnej, T.R.: Fatigue of welded structures (translation from English) WNT, Warsaw 1973 78 Olszañski, W., Su≈kowski, I., Tacikowski, J., and Zyœk, J.: Thermo-chemical treatment (Heat treatment of metals) (in Polish) Vol 5, ODOK SIMP - IMP, Warsaw 1979 DIN 50323 Tribologie Begriffe Deutsches Institut für Normung 1990 80 Senatorski, J.: Evaluation of materials for sliding friction nodes (in Polish) Dissertation Institute of Precision Mechanics, Warsaw 1994 81 Jastrzêbski, Z.D.: The nature and properties of engineering materials John Wiley and Sons, New York 1976 82 Krzemiñski-Freda, H.: Ball-bearings (in Polish) PWN, Warsaw 1989 83 £uszczak, A., Machel, M., and Wachal, A.: Tribology Friction and lubrication of machine components (in Polish) Vol I and II Military Technical Academy, Warsaw 1979 84 I¿ycki, B., Maliszewski, J., Piwowar, S., and Wierzchoñ, T.: Diffusion brazing (in Polish) WNT, Warsaw 1974 85 Garkunov, D.N.: Selective transportation in heavily loaded friction nodes (in Russian) Publ Masinostroenye, Moscow 1982 86 Simons, E.N.: Metal wear: a brief outline Frederick Muller Limited, London 1972 87 Bowden, F.P., and Tabor, D.: Introduction to tribology (translation from English) WNT, Warsaw 1980 88 Wranglen, G.: Fundamentals of corrosion and metal protection (in Polish) WNT, Warsaw 1985 89 Burakowski, T., and Senatorski, J.: Comparison of resistance to tribological wear of carburized and nitrided layers (in Polish), Trybologia, No 3, 1984, pp 4-8 90 Burakowski, T., Senatorski, J., and Tacikowski, J.: Effect of microstructure of diffusion layers on their tribological properties (in Polish) Trybologia, No 6, 1986, pp 4-8 91 Senatorski, J., and Tacikowski, J.: Tribological properties of diffusion layers on structural and tool steels Trybologia, No 2, 1988, pp 11-13 92 Senatorski, J.: Problems related to increasing of tribological properties of parts by heat treatment (in Russian) Series: Scientific-technological progress in machine-building, Edition 28 Publications of International Center for Scientific and Technical Information - A.A Blagonravov Institute for Machine Building Research of the Academy of Sience of USSR, Moscow 1991 93 Rogalski, Z., and Senatorski, J.: Über den Einfluss der thermochemischen Oberflächenbehandlung auf die Fressbeständigkeit von Konstruktionsstählen IfL-Mitteilungen, 1967, pp 11-16 94 Kostetski, B.I., Barmosenko, A.I., and Slaviskaya, L.V.: The role of crystalline structure and orientation of monocrystals in the formation of the internal wear process (in Russian) Metallofizika, No 40, 1972, pp 24-30 95 Piaskowski, Z.: The effect of surface deformation on the wear resistance of the superficial layer (in Polish) Trybologia, No 6, 1987, pp 13-15 96 Janowski, S., Senatorski, J., and Szyrle, W.: Initial research of the effect of residual stresses on wear resistance (in Polish) Science Periodicals of Rzeszów Technical University, No 82, Mechanika, vol 28, 1991, pp 127-132 97 Marczak, R.: Progress in investigations of the Garkunov effect (in Polish) Proc.: Problems of wear-free friction in machines, Radom, 12-13 May, 1993, pp 126-137 © 1999 by CRC Press LLC 98 Krol, M.: The application of metal polymers for improvement of efficiency and reliability of combustion engines (in Polish) Proc.: Problems of wear-free friction in machines, Radom, 12-13 May, 1993, pp 196-204 99 Garkunov, D.N.: Introductory presentation Proc.: Problems of wear-free friction in machines, Radom, 12-13 May, 1993, pp 6-11 100 Firkowski, A.: The mechanism of selective transportation effect and its usable aspect (in Polish) Proc.: XVI Fall School of Tribology, Pi≈a-Tuczno 1988, pp 96-102 101 Marczak, R.: The effect of wear-free friction (in Polish) Paper presented at the meeing of the Committee for Machine Building of the Polish Academy of Sciences, in Borków (Poland), 3-4 October, 1991 102 Korzski, M.: The application of burnishing to improve tribological properties of machine components (in Polish) Science Publications of Rzeszów Technical University, No 36, Mechanika, vol 15, 1987, pp 131-133 103 Willis, E.: Surface finish in relation to cylinder liners Wear, No.109, 1986, pp 351-366 104 Prowans, S.: Physical metallurgy (in Polish) PWN, Warsaw 1988 105 Przyby≈owicz, K.: Physical metallurgy (in Polish) Edition II WNT, Warsaw 1992 106 Uhlig, H.: Corrosion and protection against it (translation from English) WNT, Warsaw 1976 107 Tomashov, D.N.: Theory of corrosion and metal protection (Polish translation from Russian) PWN, Warsaw 1962 108 Akimov, G.W.: Fundamentals of corrosion science and metal protection (Polish translation from Russian) PWT, Katowice 1952 109 Klinov, I.J.: Corrosion and structural materials (Polish translation from Russian) WNT, Warsaw 1964 110 Tacikowski, J., and Zyœk, J.: Modern methods of gas nitriding Proc.: Monotheme Conference on Nitriding and Related Processes, Rzeszów, 26 June 1980, pp 24-42 111 Surface treatment for improved performance and properties Edited by J.J Burke, V.Weiss Plenum Press, New York - London 1982 © 1999 by CRC Press LLC © 1999 by CRC Press LLC © 1999 by CRC Press LLC © 1999 by CRC Press LLC © 1999 by CRC Press LLC © 1999 by CRC Press LLC © 1999 by CRC Press LLC © 1999 by CRC Press LLC © 1999 by CRC Press LLC © 1999 by CRC Press LLC © 1999 by CRC Press LLC © 1999 by CRC Press LLC © 1999 by CRC Press LLC © 1999 by CRC Press LLC © 1999 by CRC Press LLC © 1999 by CRC Press LLC Fig 5.22 Thickness of nitrided layer on surfaces A and B of a titanium sample, vs time of nitriding; process temperature T = 900ºC, p = hPa (From Roliñski, E., [20] With permission.) Surface A (external) was subjected to bombardment by ions and neutral particles formed in the plasma during glow discharge, while on surface B only adsorption processes took place because glow discharge does not penetrate such a narrow gap Obtained were nitrided layers of the same phase composition and thickness on both surfaces A and B [20] Fig 5.22 shows thicknesses of the nitrided layer on surfaces A and B of the titanium samples vs time of nitriding The significant role of chemisorption is also illustrated by investigations concerning the formation of titanium nitride layers in a chamber with the so-called hot anode, which yielded surface layers both on the cathode, as well as on the anode at temperatures of the order of 550ϒC [46] On transition metals, chemisorption of most gases, e.g., of nitrogen on titanium, is a non-activated process In the case of the nitrogen-iron system, however, a relatively small activation energy of approximately 80 kJ/mole is needed [3, 20] In the presence of atomic nitrogen, however, under glow discharge conditions, chemisorption proceeds freely without the need for activation energy Chemisorbed particles may be deformed at the surface and dissociation chemisorption may take place [38], with the formation of free atoms and radicals For these reasons, chemisorbed particles are chemically more active [4] During chemisorption, when additional energy appears, a chemical reaction may proceed As an example, in the process of formation of titanium carbide layers, the adsorbed lower titanium chlorides (TiCl2 and TiCl3) may react with carbon from the steel matrix, in accordance with the reactions: TiCl2(g) + 2H + C(s) ♦ TiC(s) + 2HCl(g) ∆G°1000 K = -373 kJ/mole (5.4) TiCl3(g) + 3H + C(s) ♦ TiC(s) + 3HCl(g) ∆G°1000 K = -450 kJ/mole (5.5) where: ∆Gϒ 1000 K - molar free enthalpy of the reaction under standard pressure at a temperature of 1000 K Recapitulating, the effect of chemisorption plays a basic role in glow discharge treatments because, intensified to a large extent by ion sputter- © 1999 by CRC Press LLC ing, it affects the process in which the following separate stages, in thermodynamic equilibrium, can be distinguished These are 1) chemical reactions in the gas phase, constituting a condition of supply of active particles of elements forming the superficial layer, 2) chemisorption of these particles at the treated surface, 3) processes of diffusion and the associated phase transformations (e.g., glow discharge nitriding and boriding) or chemical reactions at the load surface (PACVD methods, Fig 5.23) Fig 5.23 Changes in free enthalpy (∆Gϒ T) of a chemical reactions determining the formation of a titanium carbide layer under glow discharge conditions It follows then that the formation of the superficial layer may be influenced primarily by the direction of chemical reactions in the gas atmo- © 1999 by CRC Press LLC sphere This depends on the chemical composition and flow rate of the gas mixture, as well as electrical parameters It is also influenced by the appropriate preparation of new load surface from the point of view of chemisorption, which has a direct effect on diffusion processes and on the course of chancel reactions which are the essential condition of formation of superficial layers in PACVD methods 5.3 Glow discharge furnaces Units for carrying out thermo-chemical treatment of the time described in preceding sections is called the glow discharge furnace and are utilized for such diffusion processes as e.g., nitriding, carbonitriding or boriding, as well as for PACVD methods They are composed of: a working chamber, a voltage generator, a system for metering reactive gases, a vacuum system and a control-measurement system They may differ by the shape of the working chamber, by the power of the voltage generator, design of current feed-throughs, method of load fixturing, and by the method of metering of reactive gases, in particular of chlorides and metal-organic compounds In the case of furnaces used for PACVD methods, such furnaces may differ by the design of the working chamber and by the method of elimination of harmful components of the gas atmosphere exiting the working chamber, such as vapors of BCl3, HCl, TiCl 2, TiCl 3, etc In all types of glow discharge furnaces, dynamic vacuum is used This allows the establishment of a dynamic equilibrium between the basic stages of the process, i.e chemical reactions in the gas atmosphere, with the aid of technological parameters such as temperature, partial pressure and chemical composition of the gas mixture The chemical reactions are essential to guarantee a supply of active particles forming the layer through chemisorption, diffusion and the resultant phase transformations or chemical reactions of adsorbed active particles The appropriate selection of the gas mixture and treatment conditions creates a possibility of process control, in particular of microstructure and phase composition of the layer being formed, i.e of its properties Fig 5.24 Schematic of equipment used for glow discharge nitriding; - furnace; direct current supply; - load; - system for metering the mixture of reactive gases; - vacuum system © 1999 by CRC Press LLC Fig 5.25 Schematic of equipment for carrying out glow discharge processes in chloride-vased atmospheres, containing vapors of metalorganic compounds: - work chamber; - cathode; - internal screens; - direct current supply; - refrigerating system; 6, 7, 20 - vacuum valves; - “mechanical” filter; - vacuum pump; 10 - water seal; 11¸14 - metering and cut-off valves; 15 - reservoir, e.g with boron chloride or Ti(OC3H7)4; 16 - thermostat; 17, 19 - gas purifiers, 18 - gas cylinders; 21 - temperature measuring device; 22 - flow meters © 1999 by CRC Press LLC In glow discharge diffusion processes, especially in those accomplished by PACVD methods, two types of working chambers are used: - cold wall (cooled anode - chamber wall) in which the load (cathode) is heated by glow discharge; - hot wall, i.e., with auxiliary heating of the chamber (retort) walls which allows more favorable conditions of gas flow and the utilization of load polarization other than cathodic, as well as conduction of thermo-chemical treatments under reduced pressure (LPCVD methods) [33, 47, 48] Diagrams of glow discharge furnaces for nitriding and its modifications, e.g., sulfo-nitriding, oxy-nitriding, oxy-carbonitriding and boriding, as well as diagrams of versatile furnaces for diffusion treatments and PACVD and LPCVD processes are shown in Figs 5.24 to 5.27 Fig 5.26 Schematic of a versatile unit for glow discharge diffusion processes by the PACVD and LPCVD methods: - work chamber; - internal screens; - resistance heated retort furnace; - system for temperature stabilization and measurement; - gas metering system; - metering unit for the layer forming element, e.g TiCl4, Ti(OC3H7)4; - vacuum system; - pressure gauge; - voltage supply; 10 - current feed-through; 11 - load Fig 5.27 Schematic of a stand for glow discharge nitriding with a JONIMP-500/900 bell-type furnace [48]: - glow discharge furnace; - vacuum pump system; - furnace hearth; - load; - supply and control cabinets (From Trojanowski, J., [48] With permission.) © 1999 by CRC Press LLC Fig 5.28 Schematic of the JON-PEG furnace for glow discharge nitriding: - resistance furnace; - electrical supply unit for resistance furnace; - work chamber (vacuum retort); - lid; - vacuum system; - load; - thyristor direct current supply unit; reactive atmosphere metering system (From Trojanowski, J., [48] With permission.) For nitriding and its modifications these are furnaces used on a wide industrial scale They are of the pit or bell type with dimensions dependent on the size of the load Working chambers in pit-type furnaces are designated for slender and log parts which are usually nitrided in the suspended position, e.g., crankshafts, injection mold screws, cylinders On account of their big heights (up to m) they are installed in pits Modular design makes possible their extension as the need arises Chambers with bigger usable diameters are designed as bell type and in this case, the load is placed on a base Often they are designed with double base and an exchangeable working chamber which allows a more effective utilization of the furnace (Fig 5.28) Such a furnace is used for glow discharge nitriding of big and heavy parts placed in an upright position, e.g., dies [48] A glow discharge furnace for thermo-chemical treatment of complex shaped loads has been designed and built at the Institute of Precision Mechanics in Warsaw, Poland (see Fig 5.28) [48] The selection of power of the direct current power generator depends on the surface area of the treated load For example, in the nitriding process, power supply units are rated at up to 150 kW In thermo-chemical treatment with electric activation pulsed current power supply may also be used, where changes of voltage (frequency) constitute a new parameter, independent of discharge power and of other process parameters, e.g., substrate temperature, treatment time, pressure and composition of gas mixture [49-51] Schematics of furnaces powered © 1999 by CRC Press LLC Fig 5.29 Schematic representation of work chambers for carrying out PACVD processes with the application of: a) direct current voltage; b) pulsed radio frequency voltage; c) pulsed microwave frequency voltage [12]: - load; - direct current supply; - quartz tube; - radio frequency generator; - microwave generator; - load heating; - microwave hollow cathode resonator; - reactive gas inlet; - vacuum pump (From Tyczkowski, J., [12] With permission.) by pulsed current with radio and microwave frequency are shown in Fig 5.29 The application of activation by pulsed current with frequencies within the range of 10 to 50 kHz and 13.56 MHz requires design changes of the equipment and the application of appropriate power units [12, 51] The vacuum system of glow discharge furnaces is built around vacuum pumps which, at a pressure of 1013 hPa have a pumping rate of 15 to 90 m3/h and is selected in such a way, relative to the working chamber, as to assure its pumping down within 10 to 30 An appropriate set of choking valves and cut-off valves enables stabilization of the vacuum in the working chamber within the range of 0.5 to 13 hPa, with required flows of reactive gases and air backfill of the chamber after the finished process The gas metering system comprises several reduction valves, cut-off valves and needle valves, as well as flow-meters and is adapted for precise generation of gas atmospheres applied in treatment cycles In the case of metering of vapours of compounds, e.g., BCl3, TiCl4 or Ti(OC3H7)4, special designs of metering devices are used Such devices assure the generation of the reactive gas within the working chamber by either suction or by the flowthrough method [9] Fig 5.30 shows, by way of example, a schematic of the method of generation, in the working chamber, of a gas mixture from chloride atmospheres, utilized also in PACVD methods in which the choice of the process, as well as of size, shape and number of treated parts, determines the type and geometry of the working chamber, whether hot or cold wall In the first type of working chambers, i.e., with a hot anode, the walls of the chamber are surrounded by heating elements Hence, the entire chamber © 1999 by CRC Press LLC ... the power of the voltage generator, design of current feed-throughs, method of load fixturing, and by the method of metering of reactive gases, in particular of chlorides and metal-organic compounds... 11¸14 - metering and cut-off valves; 15 - reservoir, e.g with boron chloride or Ti(OC3H7)4; 16 - thermostat; 17, 19 - gas purifiers, 18 - gas cylinders; 21 - temperature measuring device; 22 - flow... of metalorganic compounds: - work chamber; - cathode; - internal screens; - direct current supply; - refrigerating system; 6, 7, 20 - vacuum valves; - “mechanical” filter; - vacuum pump; 10 -