In this study, effect of boron addition to Fe-W hardfacing alloys were investigated. The Fe-W and the Fe-W-B based hardfacing alloys were deposited on AISI 1020 steel substrates by a manual tungsten-inert-gas (TIG) hardfacing method. Obtained coatings were characterized by microstructural examinations, phase analysis and sliding wear tests. According to microstructural examinations, hardfaced samples are included three different layers which are coated zone, steel substrate and interface zone which between the coating zone and the substrate. The coating zone for the both samples any defect like crack or porosity cannot be shown. Addition of boron to the Fe-W alloy, further the Fe-W hypoeutectic structure boride phases like W2B and Fe2B phases formed on coating layer. The wear tests of the samples against alumina ball were carried out by using a ball-on-disc tribometer under the loads of 2.5N, 5N, 10N at the sliding speeds of 0.1 m/s for 250 m sliding distance. Friction coefficient of the alloys is changing between 0.44-0.64 depending on the loads. The main wear mechanism of the layer was abrasive wear.
Modern technology of deposition of protective painting and polymer coatings on metal surfaces include of the prior application of adhesive phosphate coatings on them in order to ensure reliable adhesion.
Disadvantages of phosphating process are their high energy consumption ,the implementation of advanced technologies crystalline phosphatizing requires rather complex equipment and processes themselves require tight control since the properties of coatings formed strongly depend on parameters such as free and total acidity, temperature, concentration of accelerators. In recent years, nanosized ceramic adhesive coating of zirconium oxide becomes an alternative to the adhesive layers of phosphate in staining of metal surfaces.
The paper presents influence of the vibro-abrasive machining on the operating parameters of the surface and polishing the surface of components made of steel X160CrMoV121 (NC11LV). There were used Rollwasch smoothing media made of nickel-chromium steel SB 3,1 lotto series. The process was carried out by using supportive liquid series FE-L120-B32/R. Analyzed the influence of micro machining process metal fittings on the conditions of technically dry friction. The tribological tests were performed on testing machine T-01 M Ball-on-disk. The balls used for tests were made of steel 100Cr6, the study carried out for the sliding distance of 1000 m with force 10 N. Compared the coefficients of friction technically dry before vibro-abrasive machining (samples directly after grinding) and after vibro-abrasive smoothing.
This paper describes the results of the first phase of the study preparation, structure and properties of coatings modification of black chromium oxide on copper, aluminum, iron and zirconium tubes for solar collectors. The coatings are formed by plasma spraying liquid precursors chromate method known as Liquid precursor plasma spraying. Coatings having a function of energy trap thermal radiation wavelengths of 1 µm - 3 µm in the IR region. At the same time increase the corrosion resistance of metal substrates. The nanometric structure and thickness of the coating depends on the feeding distance and the concentration of chromate precursor. For the deposition of nanometric splats melt chromium oxide has been developed a new type of feeder precursors into the water stabilized thermal plasma produced by the generator WSP®.
Corrosion resistance of coatings deposited by thermal spraying technology HVOF (High Velocity Oxygen Fuel) requires high density in coating and good adhesion to the substrate. The majority of thermally sprayed materials meet the requirements for high corrosion resistance in terms of their composition. However, the porous structure raises doubts about the performance of thermally sprayed coatings in providing of sufficient protection to the base material. In fact, corrosion protection is one of the basic coating functions. Anyway, in comparison with wear resistance research, no sufficient attention is dedicated to the issue of component protection against corrosion attack using HVOF sprayed coatings.
This paper summarizes the results of immersion corrosion tests performed on six selected corrosion resistant coatings, which are compared with nitrided stainless steel Wr.Nr. 1.4923. Following coatings were tested - two based cermet coatings (Cr3C2-NiCr, Cr3C2-CoNiCrAlY), three alloy based coatings (CoCrWC - Stellite 6, NiCrBSi, NiCrMo - Hastelloy C-276) and one experimental coating (TiMoCN-29%Ni). These coatings were selected as good candidates for the use in corrosive aggressive environments. Steel Wr.Nr. 1.0421 was used as the base material. Corrosion experiment was performed in 5% solution of H2SO4. The evaluation of corrosion attack was made before and after corrosion tests on surface and in coating cross-section after metallographic grinding using an optical microscope (OM).
Specimens made from spring steel 54SiCr6 were nitrided using various parameters of plasma nitriding in order to achieve a layer of variable thickness. The microstructure, phase constitution, hardness and case hardness depth were investigated. Subsequently notch toughness was measured by the instrumented Charpy impact test on 10x10x55 mm test specimens with U-notch 5 mm depth. Instrumented Charpy impact test was carried out at -40 °C, +21 °C and +70 °C. Results of notch toughness were correlated with the structure, chemical composition and the depth of the nitrided layers both on the surface and especially in U-notch of specimens. In the end fractographic analysis of fracture surfaces were carried out. The notch toughness is negatively influenced as a result of presence of a nitrided layer on the surface of root of U-notch and decrease again as the thickness of nitrided layer increases and with decrease in temperature. It turned out, if the nitrided layer in root of U-notch was “sufficiently” thick, the crack spread had unstable course. The change of the character of the crack spread was also influenced by temperature.
Stainless steel products undergo intensive development, especially for duplex stainless steel, who are the newest in the stainless steels family. They are characterized by a two–phase structure consisting
of approximately equivalent quantity of ferrite and austenite. Such combination of properties makes the duplex stainless steels is very attractive for numerous applications. The purpose of this study was to investigate effect of surface layer alloying with chromium carbide on the microstructure and properties of the PM stainless steel. The multiphase sinters investigated in the study were prepared from two types of water atomized steel powders: 316L and 409L. The technique of plasma spraying was applied to deposit Cr3C2 on duplex stainless steel surface. Electric arc (GTAW method) was used to surface alloying. In order to determine microstructure and basic properties of sintered duplex steel after alloying were used: optical and scanning microscopy, X-ray phase analysis, microhardness and corrosion resistance. The surface alloying with Cr3C2 is an productive method of surface layer hardening of sintered stainless steels and produce meaning modified of surface layer properties in terms of hardness and coefficient friction. Moreover, addition of chromium carbide is cause change of corrosion resistance of the duplex stainless steel.
For cooling tubes manufactured of aluminized carbon steel with inner surface welded longitudinally the question arises if the anticorrosion quality of Al coating produced on external surface can be influenced by the presence of the weld area on internal surface. In fact this quality is related to Al coating ability to prevent or at least to inhibit the corrosion process occurring during penetration of coating by water environment to the steel-coating interface. Electrochemical noise (EN) measurements provide a set of parameters which can be used to obtain useful information relating to possible impacts of time development of expected active-passive transitions in Al coating on kinetics of the underlying steel corrosion process.
The components used in the mining and construction industry, agriculture, etc., during its lifetime are exposed to the various types of wear, which include abrasion, erosion, impacts, and others. Currently, there are several variants of protective surface layers which resist wear. This group includes special weld deposits combining the metal matrix alloyed with boron and tungsten carbide grain. The parts, hard-faced already in production, can be classified to a group of composite materials that can gradually replace conventional parts made of quality steel. Using these protective layers helps to minimize the cost of repair or replacement of worn parts. The aim of the experiment is to study the properties of the weld deposit with a matrix based on iron with increased content of boron in combination with grains of tungsten carbides of size 1-2 mm using structural steel S235JR as a parent material. The influence of welding parameters, type of matrix, boron content and the size of unmelted grains of tungsten carbide was evaluated in terms of the macrostructure assessment, the HV0.1 measurement and the microstructure assessment of selected areas in the view of the possible rate of wear and service life of the weld deposit.
1.4301 steel as a basic stainless material used for undemanding applications is studied in this paper. Some of surgical instruments as well as other medical devices are manufactured from this material so its biocompatibility and corrosion resistance must be guaranteed. Electrochemical properties of this steel are closely connected to oxidic layers created on surface of material, so these properties can be improved by modification of the layer. This paper is basically focused on anodization process of substrate to gain enhanced corrosion properties. The structure of substrate was studied before and after anodization by light and electron microscopy, for basic chemical analysis of structural components of substrate before anodization and structure of created layers on surface EDX analysis was used. Relation between wettability of surface and parameters of anodization was studied. Electrochemical behaviour of anodized materials was tested in Tyrode’s solution. Open circuit potentials were found, corrosion potentials, polarization resistances or corrosion rates were determined by Tafel and Stern methods. Potentials of depassition and repassivation were measured by potentiodynamic polarization method. Electrochemical impedance spectroscopy was use for even closer description of physical characteristics of layer deposited during the anodization. For this equivalent electric circuit was found and parameters like resistance and capacitance of the layer were specified. Process of anodization is partially similar to electrochemical etching, so the relation between parameters of anodization and surface profile are also studied in this paper.
Steel reinforcement of concrete structures is normally passivated due to high pH of concrete interstitial electrolyte (pH 13-14). However, chloride contamination (e.g. deicing application, marine environment) can initiate a local breakdown of passive layer and corrosion of rebar. One of the most effective methods to stop or reduce the chloride-induced corrosion of rebar is the use of corrosion inhibitors. As corrosion inhibitors are widely used inorganic nitrites but have several limitations – they are toxic and require a critical concentration for protection of rebar (at low concentration they promote the corrosion). Therefore much attention is given to organic inhibitors which are a number of different compositions (e. g. based on amines and alkanolamines). Furthermore, organic inhibitors have cationic nature, which enables to remove chloride anions by electrochemical extraction simultaneously with electrochemical injection of inhibitor.
The paper is focused on applicability of commercial products based on dimethyldidecyl ammonium (bi)carbonate and polyethyleneimine as corrosion inhibitors for the steel reinforcement. Their inhibition efficiency was evaluated by means of polarization resistance of pre-corroded steel samples at different time intervals (15 min, 1 h and 24 h after addition of an inhibitor). The inhibition efficiency of 0.2% solutions were compared with that of sodium nitrite.
In this work, the synthesis of tin-coated carbon fibers (CFs) by electroless deposition method in aqueous solution was studied. Sodium hypophosphite was used as a reducing reagent. The composites were characterized by X-ray diffraction, energy-dispersive X-ray spectroscopy and scanning electron microscopy techniques. The experiment results showed that the deposition time played an important role in the deposition of copper layers. Continuous tin coating on carbon fiber was obtained by electroless deposition. Results showed that these tin@carbon fiber composites can be used as electrode materials, fiber-matrix composites, and so on.
This study focused on tools used in hot forging process of lid type components manufactured for the automotive industry. Tools were coated with different PN+PVD hybrid layers in order to improve tool durability. Tool wear represented by material degradation was evaluated through 3D scans of periodically collected samples. Samples microhardness and microstructure were also analyzed. Results demonstrated extent of hybrid layers efficiency in improving tool durability for industrial forging applications.
The paper describes the assessment of the quality and properties of the weld deposit by electro slag cladding using strip electrodes. As the base material used unalloyed construction steel S355J2. As filler material was used stainless austenitic steel - strip electrode OK band 309Nb, with agglomerated flux (OK Flux 10.10). There were created samples of one to three layers of weld deposit which were assessed regards the chemical composition and mixing of base material and filler metal. Furthermore, there were mapped structural changes, the course of the hardness and the thermal influence of the base material. ESW method allows the creation of large-areas weld deposits with high productivity of weld deposition creation and low degree of mixing of the base material and filler metal. These advantages predetermine the ESW method for applications in the chemical, petrochemical and paper industry, eventually for use in nuclear power.
The paper deals with the influence determination of the BH effect on the mechanical properties of the high-strength steels in dependence on the chosen cutting technology. There is tested material alloyed with boron and manganese with the martensite structure. These materials are used in the automotive industry at car-body design mainly for parts which provide the safety of the passengers. Thus to achieve and ensure these demands there is very important to know the deformation behavior of these materials already during cutting process and also after the thermal loading by which is car-body loaded during the painting process. For cutting materials there were used technologies of laser and water jet. BH effect takes place at the car-body passing through painting line where are changed mechanical properties of materials due to the elevated temperature in the oven during own baking of the paint.
This article extends the series of articles focusing on introduction and testing the behavior of impedance layer applied on cutting edge of the tool. This coating functions as a regular cutting tool coating, but also it creates an electric circuit. According to presumption of the Theory of Cutting this layer should wear out during the cutting, it means to cut down its intersection. Decreasing the intersection of the layer leads to change of impedance until the cutoff of electric conductor. The electric circuit will be disrupted. In this sense it is possible to evaluate achievement of wear out criteria of the cutting tool edge. The tools, which are able to report its wearing this way are called „intelligent tools“. This article will be analyzed and evaluated behavior of such impedance layer on exchangeable cutting edge made of cutting ceramics during cutting of X120Mn12 material.
Plasma nitriding is a great thermochemical treatment, widely used in many technical applications as
a final operation to improve the mechanical, tribological and corrosion properties of steel. This work is focused in study of mechanical and corrosion properties of 42CrMo4 steel, used for manifacturing of breech mechanism in the armament production. This article deals with wear and corrosion resistance comparison of plasma nitrided and tenifered 42CrMo4 steel. The prepared steel samples were plasma nitrided under different nitriding gas mixture at 500 °C for 10h and tenifered for 45 min at temperature 590°C followed by oxidation process for 10 min at 430°C. For comparing the properties of these chosen technologies, the test “ball on flat” was carried out on the tribometer UMT-3 device and the corrosion resistance evaluation was realized by the NSS corrosion tests in the condensation chamber. The results were supplemented by the GDOES concentration profiles analyses, microhardness (HV 0.05), surface hardness, and microstructure evaluation. Based on the “ball on flat” and corrosion tests, it was found that above evaluated technologies are suitable for increasing of wear and corrosion resistance, which can be usable for weapons production.
Low alloy carbon steels are characterised by their plastic deformation properties. These properties allow them to be formed into useful shapes such as wires. The main objectives are to characterize the microstructure of galvanized wires and to examine the effect of area reduction of wires (w) on mechanical properties. The present steel is produced by Trifisoud- Setif –Algeria using hot deep galvanization process. It is a low carbon steel wire containing mainly (weight %) 0.07%C, 0.45%Mn, 0.08%Si, 0.12% P and 0.007%S and is supplied as rods of different diameters. Microstructure identification and analysis are carried out, on material in as received and deformed conditions before and after galvanization, using optical and SEM microscope. It is found that tensile properties depend on the wiredrawing area reduction (w). The coating thickness of wires is also found to be inhomogeneous and suffer from cracks. The layer of galvanization is not homogenous and suffers from cracks and the presence of impurities inhibit the galvanization.This finding may have an important impact on the quality and cost of galvanization.
In this study we were evaluated the microstructure of borided stainless steel AISI 316L, which was borided in solid medium of EKABOR powder (5% B4C, 5% NaBF4, and 90% SiC ); the boriding treatment was performed at temperatures 800, 850, 900, 950, 1000, and 1050; for times 0.5, 1, 2, 4, 6, and 8 hours.
The study of growth kinetics of borided layers formed on surface of 316L was based on weight gain method; The presence of borides (FeB, Fe2B, CrB, Cr2B, NiB, Ni2B, Ni3B ) was confirmed by X ray diffraction, we were used optical microscope and SEM to characterized the morphology of borides formed on surface of 316L; spalling was occurred in specimens treated in high temperature and long time. According to the literature the spalling is caused by stresses in the interface FeB/Fe2B, and the difference in expansion ratio for borides .
The morphology of boride layers were smooth and compact compared to carbon steels .
Based on weight gain, and second Fick’s law, the thickness of boride layers was estimated.
The Arrhenius- equation allow to estimate value of the diffusion coefficient D0 =3.207×10-2 m2/s ; and the activation energy for the boron diffusion Q= 213.752 kJ mol-1.
Aluminum alloy is very useful in fabricating lightweight structures. However, the tribological applications of this alloy are limited. This paper present a brief study of electro spark deposition using special prepare electrode. Kerosene was used as a dielectric fluid. Surface where modification using a Fe-WC electrode on an electrical discharge machine in kerosene.
The layers were investigated with metallographic methods and EDS analyses. Using EDS analysis, there were identified a types of alloying elements and the extent of diffusion from the electrode into to aluminum alloy. Also, there was investigated of nanohardness. Microscopic examination was carried out to examine the structure of formed layers. Image analysis methods were used to observe the cross-section of the layer.
The results of investigations showed that there is a possibility of obtaining the satisfying quality joint between the aluminum alloy and Fe-WC electrode layer.
Determination of corrosion rate by means of electrochemical methods such as polarization resistance is limited to open-circuit conditions. In the case of cathodic protection, a protected object is polarized to protection potential by means of negative total current, the value of which is thus useless for quantifying corrosion rate. Long-time response physical methods, such as weight loss or electrical resistance technique are only applicable for corrosion rate determination under cathodic polarization. A novel electrochemical method employing two working electrodes allows us to determine instantaneous corrosion rate at impressed potential even if the total current is negative. Anodic current density is extracted from two consecutively measured currents. The shape of the carbon steel corrosion rate curve at the impressed potential in the potassium carbonate solution was determined. At pH 11, carbon steel was spontaneously passive, however, at cathodic polarisation to the Kuhn's protective potential, substantially elevated corrosion rate was indicated. The shape of the corrosion rate - impressed potential curve was confirmed by electrical resistance sensors exposed to aerated aqueous electrolyte under the same conditions.
Thermal spraying with liquid feedstock presents a novel route for deposition of functional coatings. In this study, possibility of preparation of titania coatings from solution by hybrid water stabilized plasma torch will be presented. Coatings were prepared from solution of titanium isopropoxide in anhydrous ethanol. Fragmentation of feedstock stream in the plasma jet was observed by shadowgraphy, deposition was carried out on steel samples mounted to the rotating carousel. Cross-sectional images from SEM microscope showed successful formation of the coating with feather-like morphology. Phase composition and crystallite sizes were evaluated by X-ray diffraction.
The durability of reinforced concrete structures is limited mainly by the reinforcement material, as which a carbon steel is widely used. Carbon steel corrosion rate increases due to carbonation or contamination with chloride anions. The activation time is strongly influenced by the concrete structure as it influences the diffusion rate of corrosion agents. Therefore, modern ultra-high performance concrete materials are designed to provide less porous structure. Electrochemical impedance spectroscopy (EIS) was used to determine microstructure of different concrete types; ordinary portland cement concrete (OPC), and two ultra-high performance concretes with different water/cement ratio. The microstructure was compared between the different concrete types, and as influenced by the time of curing. Results obtained from EIS correlate well with those of traditionally used mercury intrusion porosimetry.
In the last 20 years, the technical progress made it possible the use of very hard materials in several fields like manufacturing parts for the car industry, the railroad coaches, the nuclear power, the aeronautics and the mechanical industries.
In this paper, it was studied the evolution of the superficial layer subjected to a non-conventional treated steel, during the wear tests. The material was subjected to the thermo-chemical treatment (nitro-carburized treatment in plasma, or ion nitriding, or laser nitriding treatment) applied after thermo-magnetic treatment regimes.
The structural aspects of the superficial layers of the steel are studied after the wear process, using an Amsler type machine, taking two sliding degrees at different contact pressures and testing in time. The tests were done to detect the sustainability to the material, the evolution of the superficial layer characteristics through different tests and to establish the influence of these thermo-magnetic treatments regimes.
Currently, the hot topic in restoration and conservation of metals is the application of corrosion inhibitors intended for protection of lead. Our research aims in selection of suitable protection system which would be applicable for conservation of historical lead seals. Commonly, the seals are stored in archives together with documents to which the seal are attached. Vapour organic acids, acetic acid being a typical example, are the most aggressive pollutants in the archives environment considering corrosion of lead.
The research was focused on determination of the inhibition efficiency after various manners of lead coupons pre-treatment (corroded and electrochemically cleaned). Sodium undecanoate was used as the inhibitor in concetration of 0.01 and 0.05 mol/l. The solution was applied by immersion for 24 h. Polarization resistance measurement and electrical resistance technique were used to evaluate inhibition efficiency in neutralised acetic acid environment. Artificially created corrosion products were analysed by X-ray diffraction analysis and scanning electron microscopy was used for surface morphology observation.
Electrochemical cleaning of the surface provided high inhibition efficiency of the sodium undecanoate solution (0.05 mol/l). In general, the inhibitor was more efficient at higher concentration. It formed a layer of hydrophobic properties. Unfortunately, disadvantage of this layer is its low abrasion resistance.
In this paper are fundamentals of plasma nitriding and specific technical features of this technology explained. Preparation of samples and performing of plasma nitriding process is described in the experimental part. Plasma nitriding process was carried out on the DIN 16MnCr5 steel at 500 °C under 280 Pa in the nitriding atmosphere of H2 and N2 (l/h) for 10, 20 and 30 hours. The nitrided steel samples were studied using the GDOES spectrometry, optical microscopy, and hardness and microhardness testing. Measurements of nitride layers properties of selected steel were evaluated using the experimental methods in accordance with standards. The influence of diffusivity and of plasma nitriding conditions on the nitride layers depth was comprehensively assessed. Relation between plasma nitriding duration and depth of nitride layer was found and explained. The measurements have shown that the plasma nitriding duration has a significant influence on the nitride layer depth.
The article deals with chemical composition and mechanical properties of plasma nitrided layers after plasma nitriding process. Experiments are focused on using of plasma nitriding process for surface treatment of iron based material. Nitrided layers were applied to low alloy and high alloy steels which were subsequently evaluated by metallographic, GDOES, XRD microanalysis and microhardness methods. The results of measurement showed trends of chemical composition of alloying elements after chemical-heat treated process in deep layer. Plasma nitriding process was applied for increasing of surface hardness of material. Mechanical properties of tested material were significantly increased. Experimental work showed characteristics connection among alloying elements, esp. distribution of alloying elements and interstitial elements. Properties and thickness of nitride layer are dependent on nitride formed elements contained in core of material. The diffusion coefficient should be addict on nitride formed elements as well.
In the present paper, new coatings enriched in copper ions obtained on niobium by Plasma Electrolytic Oxidation in electrolyte containing concentrated phosphoric acid H3PO4 with copper nitrate Cu(NO3)2, are presented. It has been shown that it is possible to obtain the coatings with copper ions inside during the PEO treatment. The highest copper amount (4.05 wt/% | 1.75 at%) was detected after oxidation at 450 V in electrolyte containing 300 g Cu(NO3)2, while the lowest copper amount (1.95 wt/% | 0.97 at%) was detected after oxidation at 180 V in electrolyte containing 150 g Cu(NO3)2. The highest copper to phosphorus ratio (0.23 wt/% | 0.11 at%) was detected after oxidation at 450 V in both electrolytes, i.e. that containing 150 g as well as 300 g Cu(NO3)2 in 500 ml H3PO4. The lowest copper to phosphorus ratio (0.15-0.17 wt/% | 0.07-0.09 at%) was detected after oxidation at 180 V in both electrolytes, i.e. that containing 150 g as well as 300 g Cu(NO3)2 in 500 ml H3PO4. In addition, it was found that the higher the PEO potential used (here 450 V), the higher copper to phosphorus ratio gained.
The hydrides of the intermetallic compounds have potential applications for the realization of various storage systems and transfer of energy, specially heat pumps and energy accumulators.
XPS analysis has been used for the characterization of the electronic properties charging of CeNi5 massive specimens. Moreover, evolution of species concentrations at the surface of CeNi5 the range 500- 600°C is followed by means of Auger electron spectroscopy.
The hydrogen gas absorption at differents temperatures affects the electronic properties in the intermetallic in a similar way of what is observed in CeNi2 intermetallic compound.
The hydrogenated surface exhibits a metal-hydrogen band at 5 eV below EF. The XPS spectra of the Ce3d core levels demonstrate the existence of a hybridization effect of the 4f electrons with those of the conduction band which raises the intensity of the f0 and f2 satellites.
XPS spectra obtained after annealing at 400°C under a pressure of hydrogen, are characteristic of cerium superficial segregation at the CeNi5 surface. The corresponding composition at the surface is the CeNi phase rich on cerium.
Results obtained by AES show the segregation of impurities (oxygen and chlorine) and cerium at the surface of CeNi5. An AES observation of cerium segregation at 500°C is greater than at 400°C. These observations are in good agreement with XPS analyses showing cerium enrichment at the surface of CeNi5 intermetallic compound. An evaluation of the cerium enrichment is in good agreement with estimates obtained from the XPS measurements.
Carbide coatings prepared using the HP/HVOF technology are widespread and commonly used surface treatment. These coatings provide various advantages compared with the substrate material and are able to supply top mechanical and corrosion properties at low cost. On the other hand, the removing of carbide coating is a big problem. It is not important if the removal is necessary for the renovation of the part or if there was a production error and there is no other way of repair than a complete removal of the coating from the substrate. The problem is that these coatings have the highest hardness (around 90 HRC), which reduces the number of possible ways of removal. More precisely, there is only one method suitable for this operation and it is grinding (time consuming, expensive and with limited geometry of use…). This paper aims at the use of electrochemical removal of carbide coatings, which can fully replace the grinding. The benefits are low cost and the possibility of removing the coating from a shaped surface. Results in this article show the removal of the CrC-NiCr coating prepared by means of HP/HVOF (JP-5000). The main aim was to evaluate the efficiency of this process, which is assessed as a weight loss of the coating after predetermined time. The final surface was evaluated using the optical microscopy with the focus on the mechanism of removal and the quality of the substrate material.
The article presents the results of research on the influence of the conditions of erosion mechanical machining using a brush electrode on the formation of the surface layer properties. The physical interactions which occur in the process and affect the formation of the surface layer properties have also been described. It has been noted that it is possible to achieve compressive stress in the process by choosing proper parameters. A mathematical model and results of a simulation of the mechanical influence of a single filament on the machined surface have also been presented.
The paper deals with the steel 41CrAlMo7-10 fatigue characteristics changes following the plasma nitriding process. Two sets of samples were heat-treated identically. Then they were subjected to a plasma nitriding process. The mixture rate of basic gases, hydrogen and nitrogen, forming the atmosphere during the plasma nitriding, was mutually inverted. Process parameters such as the time, applied voltage and pulse length were identical for both sets. Following the heat treatment and surface coating formation of the diffusion layer of nitrides both sets were subject to rotating bending fatigue testing in the machine R.R.Moore L2568 of Instron Co. The fatigue tests were carried out in accordance with the CSN 42 0363 Fatigue Testing of Metals, Methodology of Testing. Then, the tests were evaluated numerically and graphically using Wöhler`s (S-N) curve in a semi-logarithmic form. The testing resulted in either the test sample fracture, or at completion 107 cycles. Evaluated were inclusions in the test bar fractures whereat the stress nucleation and fracture initiation took place. Calculated was the stress intensity factor ΔKImax declared in MPa.m0.5. Thanks to the completed testing, derived and analysed results new knowledge was acquired in the field of plasma nitriding steels.
The paper presents a system to optimize, control, visualization and data storage PVD processes. The system has been designed based on LabVIEW and has been successfully used in the optical industry. Visualization is very intuitive for the operator, provides an easy opportunity to control all process parameters. Saved data allow you to create a library that allows to improve the quality of coatings and gives you the ability to analyze processes. The low cost of the introduction of the system also makes it a very useful tool for modifying older vacuum coaters and gives a chance to its gradual expansion. The collected libraries allow you to recreate and optimize the process of applying layers of materials.