Plasma Hardening Research Articles

Deposition of Coatings for Raising the Wear Resistance of Friction Surfaces of Spherical Sliding Bearings

The process of finishing plasma hardening with deposition of a multilayer amorphous coating of the Si – O – C – N system is considered as applied to hardening of the friction surfaces of spherical sliding bearings. The microrelief, the submicrorelief, and the tribological characteristics of the deposited wear-resistant antifriction amorphous coating, which are responsible for the elevated wear resistance of spherical sliding bearings, are investigated.

Improved Efficiency of the Process of Low-Temperature Plasma Hardening Based on its Monitoring

Investigations on the feasibility and development of the monitoring process for the lowtemperature plasma hardening of metal items are carried out. It is shown that it is reasonable to carry out monitoring according to the parameters of the signals registered in the plasma-item-stand-earth electric circuit and analyze it with the help of the value (Hurst exponent) numerically reflecting the main formation regularities and change of the signal structure in the hardening process. Requirements on the monitoring system providing the valid information support of low-temperature plasma hardening are formed. It is deduced from the experiments that the maximum hardened surface layer is formed if the hardening process is accompanied by signal generation with the minimal Hurst exponent values.

Improvement of Friction Surface Wear Resistance by Plasma Treatment

Features are considered for the structure and formation of a heat-affected zone with surface plasma hardening based on high-carbon steel of type 60G. Original procedures are developed for determining tribological properties with dry friction and abrasive wear. Test results are given for the wear resistance of hardened layers with optimum treatment regimes and different alloys of steel 60G with carbon and chromium. Comparative study is provided for some widely used steels, metallized coatings and nickel powder layer surfacing.

Impact of plasma hardening on the wear resistance of 38XC steel

The impact of plasma hardening on the wear resistance of 38XC steel was studied. It has been found that the wear resistance increases by 53.7 times under the condition of dry friction compared to the normalized state and by 12.7 times compared to the improved state. During plasma hardening, the wear of 38XC steel under dry friction is equal to the normalized steel 15 with lubrication; and the wear is not increased in case of a 1.5-fold increase in the load. The addition of HADO revitalizant to oil contributed to an approximately twofold decrease in the wear of 38XC steel with plasma hardening during wearing-in after cutting off the lubricant.

Plasma Case Hardening of Wear-Resistant High-Chromium Cast Iron

The effect of plasma parameters on the case hardening of wear-resistant high-chromium cast iron in different structural condition is studied. Correlation relations were established between the initial and finite microstructure of the surface layer formed after plasma hardening at different heating rates. Microhardness profiles over the cross-section of the modified layer are structurally substantiated. Recommendations for optimizing the complex bulk-surface cast iron treatment conditions are given.

Differential heat treatment of one-piece freight-car wheels

Differential quenching of the whole one-piece wheel is shown to be more effective than quenching of only the contact surface at the wheel rim. Hybrid strengthening by differential bulk quenching and surface plasma hardening is very promising in increasing the crack resistance of steel. The martensitic structure of the treated layer in hybrid strengthening is very disperse, thanks to decrease in size of the initial austenite grain. In bulk-quenched components, surface plasma strengthening creates a composite working layer characterized by high wear and crack resistance, whereas the core is relatively soft and plastic.

13th International Conference on Films and Coatings

13th International Conference on Films and Coatings

The Cathodic Electrolytic Plasma Hardening of Steel and Cast Iron Based Automotive Camshafts

The Cathodic Electrolytic Plasma Hardening of Steel and Cast Iron Based Automotive Camshafts

Fluctuations in the Process Plant as a Quality Assessment Criterion of Low-temperature Plasma Hardening Process

The paper presents the results of experimental studies of the vibrational processes in low temperature plasma hardening. The relationship between the pulsations of a plasma cloud, generator electrical fluctuations of microwave energy and the mechanical fluctuations of the working chamber process plant has been established. On the basis of these results the work makes the conclusion about the need to monitor the process to ensure its quality, and the possibility of using statistical methods of processing data on displacement current based on the test of the hypothesis on the presence of this trend in its signal.

Effect of bulk heat treatment and plasma surface hardening on the microstructure and erosion wear resistance of complex-alloyed cast irons with spheroidal vanadium carbides

The results of an investigation of the effect of bulk quenching from temperature in the range of 760–1050°C, cryogenic treatment (–196°C) and surface plasma hardening on the abrasive-erosion wear of frugally alloyed V–Cr–Mn–Ni cast irons with spheroidal vanadium carbides have been presented in this article. It has been found that cast irons containing 5.0–7.5% V, 4.5–9.0% Cr, and 5.5–5.7% (total) of Mn and Ni after heat treatment have a 2–3-fold advantage in wear resistance compared to the prototype high-vanadium cast iron (11.9% V, 12.9% Mn). The maximum wear resistance of cast irons studied is achieved by quenching at 760°C followed by plasma surface hardening, as well as quenching at 840°C, followed by cryogenic treatment. These treatments result in the formation of an optimum microstructure that consists of spheroidal vanadium carbides, eutectic carbides M7C3, and a martensite-austenite matrix reinforced by secondary carbides. The increase in quenching temperature leads to an increase in the amount of residual austenite and decrease in the erosive wear resistance of cast irons.

Properties and Commercial Application of Manual Plasma Hardening

A new method and a device for plasma hardening of various parts are considered. Installation of the new device does not require too much investment (the active mechanical productions are appropriate for its accommodation) and special choice of personnel (welders train to use it without difficulty). Plasma hardening does not deform and worsen the smoothness of the surface, which makes it possible to employ many hardened parts without finishing mechanical treatment required after bulk or induction hardening. The hardened layer (about 1 mm) produced by plasma hardening exhibits better wear resistance than after bulk hardening with tempering, which prolongs the service life of the parts.

Physical processes and modeling of plasma deposition and hardening of coatings-switched electrical parameters

This paper presents the results of simulation of plasma deposition and hardening of coatings in modulating the electrical parameters. Mathematical models are based on physical models of gas-dynamic mechanisms more dynamic and thermal processes of the plasma jet. As an example the modeling of dynamic processes of heterogeneous plasma jet, modulated current pulses indirect arc plasma torch.

Структурно-масштабные уровни плазменного упрочнения чугунных валков

Структурно-масштабные уровни плазменного упрочнения чугунных валков

Features of thermal processes of plasma deposition and hardening of coatings with external modulation parameters of the arc

In the work on the basis of mathematical modeling analysis of processes of plasma deposition of coatings with modulation of the electrical parameters of the extension arc. The effect of modulation on the temperature field in the system "coating-basis" on a local scale, proportionate to the diameter of the spot attachment of the arc to the surface, and at the macrolevel of evaporation surface. It justifies the preconditions of the improvement of plasma deposition and hardening coatings.

Hardening treatment of friction surfaces of ball journal bearings

The article presents the technology of finishing plasma hardening by the application of the multi-layer nanocoating Si-O-C-N system to harden the friction surfaces of the ball journal bearings. The authors of the paper have studied the applied wear-resistant anti-friction coating tribological characteristics, which determine the increase in wear resistance of the ball journal bearings.

Mathematical modeling of plasma deposition and hardening of coatings-switched electrical parameters

This paper presents the results of simulation of plasma deposition and hardening of coatings in modulating the electrical parameters. Mathematical models are based on physical models of gas-dynamic mechanisms more dynamic and thermal processes of the plasma jet. As an example the modeling of dynamic processes of heterogeneous plasma jet, modulated current pulses indirect arc plasma torch.

Optimization of modes of plasma treatment crane rails

Crane operation is accompanied with wear and tear of rails and crane wheels. Actual direction is the renovation and improvement of efficiency of these parts. Modern technologies of restoration of wheels and rails provide surface deposition or treatment with high-frequency currents. A promising direction is a surface treatment of highly concentrated streams of energy: with a laser beam, plasma jet. It is proposed to increase the efficiency of crane rails of surface plasma treatment. The work was carried out on the selection of treatment regimens. Simulation of the thermal impact of the plasma jet on a solid body of a complex shape was performed. Defined were multiple ranges of plasma hardening regimes that meet the requirements of production. The structural transformation of the material in the crane rails plasma treatment was investigated. It is concluded that in carbon and low alloy crane steels plasma exposure zone is characterized by a high degree of dispersion hardened structure and higher toughness as compared to the quenching with high-frequency current. Both shift (within the upper zone of plasma influence) are realized, and fluctuation (in the lower zone of the plasma effect) mechanisms of phase transformations. With high-speed plasma heating is a major transformation of granular or lamellar pearlite into austenite. The level of operational properties of hardened steel, which is achieved in this case is determined by the kinetics of the completeness and pearlite → austenite transformation. For carbon and low alloy rail steels plasma hardening of achievable properties can effectively replace the bulk hardening, hardening by high-frequency, or surface deposition. The range of conditions for plasma treatment was determined which allows to obtain a surface layer with a certain performance properties.

Study and Use of Chromium Steel Plasma Hardening

Chromium steel (12% Cr) surface layer microhardness and microstructure after plasma hardening are studied. Friction tests show that plasma hardening increases chromium steel wear resistance by more than two orders of magnitude. Use of UDGZ-200 equipment makes it possible to perform hardening without deformation for steel 20X13 “races.” Hardened race withstand standard acceptance tests.

Wear resistance of high-carbon steel with dry friction and abrasion

Assessment of the wear resistance in wheel–rail contact by determining the tribological characteristics of high-carbon steel in dry friction is proposed. Comparative test results are presented for such steel, as well as for hardened layers of wheel steel with optimal plasma surface hardening and different carbon and chromium contents. The wear resistance of the working surfaces of high-carbon wheel and rail steels in dry friction and abrasion is determined. The plasma hardening of locomotive wheel pairs with increased hardness of the outer wrap and one-piece freight-car wheels made from chrome steel is optimized. The change in wear resistance is confirmed in abrasive-wear tests. Test results for carbon and high-carbon steels are compared, as well as results for layers after plasma powder surfacing and plasma surface hardening.

Plasma Hardening of a Steel 30KhGSA Surfacing Layer

Plasma Hardening of a Steel 30KhGSA Surfacing Layer