Zinc and Zn-alloys maintain their importance in corrosion protection of steel substrates. Increased protection is achieved by physical barrier between substrate and environment and by effect of sacrificial anode. In both ways dissolution of coating takes place. Increased corrosion performance can be achieved by suitable alloying. The aim of the work was to observe the influence of various amount of Sn (0, 0.5, 1, 2 and 3 wt. %) on corrosion resistance of alloy Zn1.6Al1.6Mg suitable for hot dip galvanizing. Alloys were prepared in electric resistance furnace. Solidification of all alloys was performed on air. Dimensions of samples for SST were Φ30x8 mm. One side of sample was metallographically prepared and exposed to a 5% water solution of NaCl in corrosion box. Exposure time was set to 250h and 500h. Qualitative and quantitative analysis of corrosion products was executed by x-ray diffraction. Samples were cleaned from corrosion products and weighted for determination of weight changes after SST. Topography of exposed surface was observed using laser scanning confocal microscope. Process of corrosion invasion was observed on cross-sections by light microscopy. It was found out than the addition of Sn causes weight gain of exposed samples observed even after cleaning from corrosion products.
The Paper presents effect of the main dimension of smothing media used in the vibro-abrasive machining. There were used Rollwasch smothing media profiles PB series made of polyester. Media were cone-shaped, with different mainability. The process was conducted for three frequencies of tumbler: 2000 Hz, 2500 Hz, 3000 Hz. All processes were conducted for 60 minutes. Examined the effect of the type there were used for smoothing surface. Analyzed material were made of aluminum alloy.
Following the tests, the surface roughness and waviness of the machined job were measured by using optical profilometer Talysurf CCI Lite - Taylor Hobson. To illustrate the surface taper ratio and edge optical microscope Nikon MA 200 Eclipse with the image analysis system NIS 4.20 was used.
Analysis of the vibration smoothing technology in terms of technical refers mainly to compare the results of the geometric structure of the surface. The process was carried out by using liquid supportive Series ME L100 A22/NF. Finally, the 3D analysis of the surface topography for all samples was carried out. Deburring processes were compared.
This paper describes the results of studies of the properties of ceramic coatings of corundum-badeleyite ceramics, deposited on the surface of boronized stainless steel AISI 303. Boronizing a steel surface is a technology that has been known for decades. In addition to increasing the surface hardness and related abrasion resistance, some variants of boronizing can contribute to a corrosion protection of steel. The benefits of these applications) can be multiplied by creating ceramic coatings with higher hardness, heat resistance, corrosion resistance and lower surface porosity. In such a case borides on steel produce interlayers with a suitable coefficient of linear thermal expansion against the ceramic coatings which are applied by the method of thermal spraying or, plasma spraying. Conditions of boronizing are described using a reactive diffusion method of boron from boron carbide and lanthanum hexaboride so that the formation of Fe2B is preferred to FeB which is more brittle and whose structure does not satisfy the conditions for perfect adhesion of modified zirconia ceramics. Perfectly rigid adhesive connection of needle-like embedded interlayers Fe2B in steel AISI 303 prepared by reactive diffusion of a boronizing medium without activators at 1000 ° C and exposure of 2-4 hours has the value of 20 - 24 MPa at the Pinn-of test. Ceramic coatings from Al2O3-ZrO2 ceramics formed on those interlayers have the value of bond strength up to 14 - 20 MPa. Thermal cycling between 100 °C - 600 °C confirmed good adhesion of coatings with the underlying steel.
This paper investigates the oxidation behaviour of aluminized flake graphite cast iron. Aluminized coatings were fabricated by hot-dipping cast iron in a pure Al or AlSi11 bath at 750 oC for 20 min. The microstructure analysis showed that both types of coatings consisted of two layers: an outer layer with a composition similar to that of the aluminized bath and an inner layer with intermetallic phases. Dispersed flakes of graphite were observed in both layers. The coatings fabricated in AlSi11 were thicker than those produced in pure Al. High temperature oxidation tests of aluminized and bare cast iron specimens were conducted over a period of nineteen 24-hour cycles. It was shown that flake graphite cast iron hot-dip coated with pure Al or AlSi11 alloy exhibits comparable high temperature oxidation resistance to uncoated cast iron.
Cr3C2-NiCr, Cr3C2-CoNiCrAlY, TiMoCN-Ni (experimental coating), Stellite 6, NiCrBSi and Hastelloy C-276 coatings were deposited on substrate material Wr.Nr. 1.4923 (X22) which is in nitrided state used as an effective constructional material for components in power equipment. All evaluated coatings were deposited using HVOF (High Velocity Oxygen Fuel) thermal spraying technology. The evaluation of resistance against high temperature corrosion was conducted for all selected thermally sprayed coatings. Furthermore, corrosion resistance comparative study between coating surface protection and nitrided stainless steel X22 was also carried out. All evaluated coatings were exposed to corrosive-aggressive environment in the form of molten salts mixture with composition of 60% V2O5 and 40% Na2(SO)4 at the selected temperature of 750 ° C. Further, all coatings were exposed to cyclic conditions. Each cycle included one hour long exposure of evaluated coatings with salts mixture layer on the surface at 750 ° C in a silicon carbide furnace. 20 minutes cooling in air followed the exposure period. Weight changes of individual samples were measured after every cycle and the results were recorded in the diagram.
After the corrosion tests, all coatings were analyzed using light and scanning electron microscope (SEM), and also the analysis of elemental composition (EDAX) was conducted. Alloys-based coatings showed very similar corrosion mechanism in the selected aggressive environment and the same can be stated about cermet coatings. The obtained results prove that HVOF deposited coatings can replace current surface protection of components in power equipment such as nitriding.
The paper describes the study of porous layers formation process made with Fe on the carbon steel base. To form the layer there was used method of consisting combination of pulse microwelding paste layer on the S235 steel surface. The paste layer was combined as a mixture of different powders like Fe2O3, Fe, Cu and mineral oil. The resistive pulse microwelding techniques were applied on the layer. Whole process of applying layers was controlled manually. The deposit was sintered with reduction oxides in dissociated ammonia. There was prepared mixture of iron powder ASC 100.29, ASC 100.24, Distaloy SE (source: the Höganäs company) and iron oxide in various compositions. To mixtures there were also added Cu, in order to improve the layer properties after sintering. Because the base material and the paste composition are being very similar by the chemical composition, only Cu has been recognized as the best key indicator enabling diffusion proccess study. Therefore Cu plays the role of an indicator that allows the assessment of the sintering properties, including the depth of diffusion. 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 Fe foam into to S235 steel. Also, there was investigated microhardness by Vicers method. Microscopic examination was carried out to examine the structure of formed layers. Image analysis methods were used to measure the size of the cross-section porosity. Studies have determined basic quality parameters of the covered layers.
The aim of this work is a description of the influence of plasma nitride layers with different case depths which were created in the root of V-notches to notch toughness of 30CrMoV9 steel. The different case depths of nitride layers were achieved during three nitriding processes at temperatures 450 °C, 500 °C and 550 °C. Duration of nitriding process was chosen with regard to the achievement of uniform depth layer on steel surface because determination the final depth of the root of the V-notch is difficult. Chemical composition of steel was verified for selected chemical elements by GDOES/Bulk method using the LECO SA 2000 device. The experimental works were realized on V-notch samples of size 10x10x55 mm (according to CSN ISO 148-1 standard). The notch toughness tests of steel were carried out using the instrumental Charpy hammer at temperatures -40 °C, +21 °C and + 70 °C. Thickness and microhardness of plasma nitrided layers was evaluated using the automatic microhardness LECO M-400-H device. The metallography was aslo evaluated using a light microscope OLYMPUS GX51. The results of experiments showed that plasma nitriding process has a direct impact on the change of notch toughness parameters. The notch toughness of plasma nitrided steel was decreased. The primary influence on the notch toughness has the case depth of the nitrided layer at the root of the V-notch. The measurements thereinafter showed that the notch toughness values at low temperature (-40 °C) decreased but at higher temperature (+70 °C) decreased too.
The aim of this work was to examine effects of surface treatment with high energy sources on microstructure and properties of austeno-ferritic stainless steel sintered in dissociated ammonia. The investigated multi-phase sinters were prepared from two types of water atomized steel powders: 304L and 434L. Surface remelting was conducted by using of two devices: electric arc (GTAW method) and Nd:YAG impulse laser. In order to determine microstructure and basic properties of sintered steel after remelting the following research methods were used: optical and scanning microscopy, X-ray phase and stress analysis, microhrdness and surface roughness measurements and tribological test. It was found that remelting process leads to formation of continuous, free from porosity, structure-homogeneous surface layer. The microstructure of laser remelted surface layer was finer than after arc remelting but in both cases X-ray analysis revealed presence of austenitic phase only. The microhardness of laser threated layer was slightly higher (322 HV 0,05) than after arc process (312 HV 0,05). The measurements of surface geometry parameters (Ra, Rz, Rmax) showed that after impulse laser remelting the roughness is much higher in comparison with sinter in the initial state what is the consequence of relief occurrence. Wear behaviour of investigated sintered steel was examined in dry sliding conditions. It was found that wear coefficient of threaded samples is comparable with those of initial material. The major wear mechanism of sinters after remelting was adhesion while in the case of sinter in the initial state- abrasion.
CoNiCrAlY bond coats manufactured by the high-velocity oxygen-fuel spraying (HVOF) and cold gas dynamic spraying (CGDS) deposition technique have been investigated and comparison of phase modifications is presented in the paper. Even though both techniques accelerate powder particles with high kinetic energy, the resulting coatings differ considerably in their microstructures. In the former, high pressure is created by burning gases such as acetylene, propane or kerosene at high pressure and generating high temperature (3500 to 4500 °C) in the gun. This gives high acceleration to powder particles which melt and deposit on substrate layer by layer with splat cool mechanism. On the other hand, large kinetic energy is generated in cold spray by passing carrier gases such as He or N2 through converging-diverging nozzle, with lower gun temperature of around 600 °C. Here the particles are not liquid droplets because of lower temperature and the deposition mechanism is not a splat cooling, but a high impact of solid particles, which results in plastic deformation, making very adherent coating. In this work, CoNiCrAlY powder was deposited on Inconel 718 substrate using HVOF and CGDS deposition process. The bond coats microstructural features were characterized by means of SEM and XRD analyses. The experimental results demonstrated that the CoNiCrAlY bond coats prepared by both HVOF and CGDS technique displayed the lower porosity for CGDS microstructure, and therefore CGDS represents an interesting and promising alternative for their manufacturing.
Zn alloys are commonly used for coatings of steel products of various shapes and applications. This is due to their corrosion resistance, toughness and also decorative properties, which can be further improved by suitable alloying. Two main alloying elements are Al and Mg. Aluminium creates a passivation layer which improves a corrosion resistance, brings higher brightness with higher amount of spangles. Magnesium brings also a higher corrosion resistance, however it decreases formability at higher concentrations mainly due to presence of brittle Zn2Mg phase. Poster deals with the modification of Zn-based ternary system with 1.6 wt. % of Al and 1.6 wt. % of Mg. Sn was added into molten alloy in the production process on defined concentrations: 0, 0.5, 1, 2 and 3 wt. %. Tin effectively neutralises highly reactive elements as silicon and phosphor in zinc bath and prevents from excessive coarsening of coating. However, high amount of tin increases a tendency to intergranular corrosion. Cylindrical cast of five alloys with different amount of tin was prepared. Development of microstructure and phase composition was observed using scanning electron microscopy, x-ray diffraction and differential scanning calorimetry. Increasing amount of Sn causes changes in formation of phases during solidification process and modifies quantity of phases present in alloy: Zn, Al, Zn2Mg and Mg2Sn. It was found out that amount of Mg2Sn increases with increasing tin content at the expense of Zn2Mg.
Laser technologies are among the unconventional methods of heat treatment and machining. Among the biggest advantages of laser quenching (hardening), it can be included high speed and process efficiency, a narrow thermally affected area and the possibility of processing complicated parts in shape that could not be workable with common conventional methods. During laser quenching of large surface parts, it is necessary to solve the problem of mutual overlap of laser spots. There is an unquenched area when insufficiently overlapped; with a large overlap, it can occur a tempering of the already quenched belt. Both cases negatively influence the resulting structure and mechanical properties.
This article deals with finding the optimal degree of point laser spot overlap to ensure a high-quality quenching of large surface parts and with setting appropriate quenching parameters.
The paper deals with the evaluation of sheets with surface coating on the basis of Zn/Mg/Al and their application possibilities in the automotive industry. Evaluation is carried out by determination adhesive joints strength acc. to ISO 11339 for three adhesives producers from many who supply sheets for car-body parts production. Utilization of new types of materials means also necessity to test individual bonded car-body parts utility properties, mainly at peel test under certain temperature conditions simultaneously in dependence on type of adhesives and lubricants which are used in the drawing technological process. Results give sheet processors information about properties of sheets with these surface coatings from individual producers, behavior of bonded joints strength properties together with failure mode as a criterion for propriety selection to apply new types of coating on the basis of Zn/Mg/Al.
In this study, the effects of bismuth additions of 0.2, 0.5 and 1 wt% on microstructure and mechanical properties of AZ91 alloy were examined. A permanent mold casting procedure was carried out to produce the alloy billets under a mixed gas atmosphere of SF6 and CO2. Microstructural investigations showed that Mg3Bi2 intermetallic phases were formed in all the samples and it coarsened with increasing amount of Bi in AZ91 alloy. Furthermore, a finer dispersion of Mg17Al12 intermetallic phases was observed in the structures as the amount of Bi in AZ91 increased. It was also showed that Bi addition increased the hardness of AZ91 alloy. However, the highest hardness value was found for the alloy having 0.5wt% Bi addition that means high amount of Bi can decrease the hardness of AZ91 alloy. On the other, there were no considerable changes in the tensile strengths and yield strengths of the alloys as the amount of Bi increased although a slight increase in both strengths were observed with increasing amount of Bi. Percent elongation at break showed a decrease as Bi addition increased.
The galvanic Zn-Ni alloy coatings are ones of the most effective anodic coatings, which are used to corrosion protection of steel elements. In spite of the excellent anticorrosion properties of the Zn-Ni coatings, for the sake of a fact that they do not fulfill the industry requirements, a realization of additional treatment improving their corrosion properties is most often necessary. In order to significant improvement the corrosion properties of zinc-nickel alloy coatings, the conversion coating formation on their surface is realizable.
The results of investigations on surface morphology, chemical and phase composition as well as corrosion properties of anodically oxidized Zn-Ni alloy coatings electrodeposited on steel substrate have been presented in this work. The process was carried out in saturated calcium hydroxide solutions. The XRF, XPS, XRD analytical methods have been used in the research to determine the composition of the formed layer. The corrosion properties were characterized by potentiodynamic polarization method. The SEM images received during the microscopy research showed, that the structure of coatings was changed. On the basis of the realized investigations on their composition it was found that the conversion coatings consisting mainly of zinc oxide is formed in the result of anodic treatment of the Zn-Ni coatings in the hydroxide solution. Moreover, the results of the XPS studies indicated that zinc hydroxide as well as nickel oxide and nickel hydroxide were also formed on the coatings surface.
This work was supported by The National Centre for Research and Development under research project no. LIDER/009/433/L-4/12/NCBR/2013
Currently, the methods of material coating by CVD (Chemical Vapour Deposition) and PVD (Physical Vapour Deposition) are expanding considerably. These methods are used in engineering and other industries. There is a large variability of the second coating. Their properties can be combined using several layers of different materials. The coatings have excellent physical and chemical properties e.g. low friction, high hardness, abrasion resistance, high temperature (normally 550 °C but 750 °C or more), corrosion and acid resistance. For the use of materials with such coatings, the knowledge of their tribological properties is necessary.
Reinforced concrete service-life depends on transport rate of corrosion stimulators, especially chlorides, towards the reinforcement through concrete cover layer. Traditional migration tests are able to state the effective diffusion coefficient, however, they do not provide the information about the microstructure and its development in time. The electrochemical impedance spectroscopy was applied to study the microstructure of two types of ultra-high performance concrete, Ordinary Portland cement concrete and pore concrete. The porosity and electrochemical parameters were related to water and chloride permeability.
The article focus on the corrosion problems in the rolling stock. The article presents various factors which determine the speed and intensity of corrosion process. Such factors include construction materials, geometry, treating these materials, the variability of weather condition and human factor. Attention is given to provide adequate service to extend corrosion resistance of entire system. The article presents costs associated with removal effects of corrosion. The article presents anticorrosion coatings system with transparent layer with reduced adhesion of each subsequent types of contamination which secure system from harmful external factors, lets the corrosion resistance of the entire system can be extended.
Silver cementation with zinc powder from residual X ray fixers (XRF) was studied. The chemical analysis of XRF showed 5.16 g/l (Ag), 0.56 g/l (Al), 5.24 g/L (K), 7.02 g/L (Na) and 172.56 g/L (S). The cementation process in terms of solution pH was thermodynamically modeled using FactSage by constructing the potential-pH diagram at 298.15 K. This diagram showed that the cementation process leads to metallic silver together residual unreacted zinc. The effects experimentally evaluated were: pH (ranged from 3.0 to 7.0), temperature (ranged from 298.15 to 318.15°K) and Ag/Zn (1:1, 1:2, 1:3, 1:4 and 1:5). The maxim silver cementation (99.93% Ag) was obtained at 30 s of reaction, pH 6.0, 298.15°K and Ag/Zn equal to 1:3. Ag cementation decreases for pH values of 3.0 and 4.0 and temperature values of 303.15 to 318.15°K. The X-Ray and SEM-EDS results showed that the cementation product is formed by Ag and Zn.
This article deals with experimental determination of cutting tool wear during machining of Ti6Al4V alloy. This alloy features worsened machining ability that has direct influence on wear intensity and durability of cutting tool during machining. Worsened machining ability usually negatively demonstrates itself by lowered quality of machined surface and subsurface layers of the material. The experimental part was focused on measuring of amplitude and progress of the tool cutting edge wear during machining of Ti6Al4V material. The amplitude of the tool - exchangeable edge inserts with deposited PVD layers - wear was determined by direct measurement of linear dimensions according to the ISO 3685:1993 standard.
The article presents the results of the microstructure of alloy coatings on a substrate bearing bronze. Such a variant is used for plain bearings in order to improve the running performance. The research shows method of preparing specimens, a set of photographs at different magnifications and analysis at selected points. Studies are supplemented with measurements of microhardness of the surface layer. Research has identified the basic elements of the microstructure of the coating.
One of very important requirements for measuring devices is fact that measured values of observed quantity will be in specific tolerance zone of actual value also after longer period of use.
Deviations of actual value can be caused by several factors - improper handling with devices, inadequate maintenance and storing, aging of materials of which they are made and last but not least, by wear of single parts.
The target was to define the way of wear elimination of most faulty parts of dial gauges to obtain the maximum possible lifetime with minimal possible costs. Since, the using of more resistant material for producing of faulty part is difficult economically, for eliminating of wear, there was used the coating method for given part. By experimental results, it was choosen suitable way of coating.
This paper provides a compare sliding wear behaviour of thermally sprayed coatings at room and high temperature, representative of the high temperature is temperature 600°C. Evaluation is focused on method for linearly reciprocating Ball-on-Flat sliding wear according to ASTM G133-05 so called fretting test using the tribometer CETR-UMT3. The thermally sprayed coatings represent CrC-based HVOF cermet coatings with matrix material CoNiCrAlY alloy. The evaluation addresses specifically wear resistance, friction characteristic and sliding wear mechanisms. The coatings were examined by SEM imaging.
This paper describes experiments for the development of methods of non-destructive, non-contact surface diagnostics. This is oriented on technical systems in metallurgical operations with usage of laser scanners and digital image processing techniques. There are presented the results of the surface quality evaluation of various metallic materials, in both conditions, cold and hot. The experimental results were used to design diagnostic equipment to support decision-making processes concerning controlling processes in metallurgy.
The study compares the microstructure of the dispersion strengthened Cu – MgO composites prepared by thermo-chemical transformations of precursors and mechanical milling followed by spark plasma sintering technique. The effect of two different MgO contents (3 and 5 vol.%) on formation and stability of the copper matrix nanostructure is analysed. The structure development of the powder during its preparation and compact is characterised by metallographic observations and X-ray diffraction analysis. From the results follows that both the MgO contents are sufficient for effective strengthening the Cu – MgO nanostructure.
Nanocomposite films Nb-Al-N produced by magnetron sputtering were researched in this work. Two stable crystalline structural states were found in the films: NbNch and solid solution В1−NbxAl1-xNyO1-y, and also an amorphous component associated with aluminum oxynitride with reactive magnetron sputtering. Sensitivity of substructural characteristics was set up to the current supplied to Al target and their relationship with the characteristic nanohardness and Knoop hardness. Recent changes in the range of 29-33.5 GPa and 46-48 GPa, respectively. Initial principle calculations of phases NbN and Nb2AlN and also heterostructures of NbN/AlN were carried out for the interpretation of the results. The work was performed as a part of two complex state programs: "Development of nanostructured superhard coatings formation foundations with high physical-mechanical properties" (number 0112u001382) and "Physical principles of plasma technologies for complex processing of multicomponent materials and coatings" (number 0113u000137c).
Surface treatments of metals are important areas of mechanical engineering. Galvanizing, which is a zinc coating on the steel base material by electrolytic deposition, belongs among the wide range of methods. Zn layer protects anodically the base material (usually unalloyed or low-alloy steel) against corrosion. In the final phase of the galvanic process final finish is performed - yellow or blue chromate surface coating. For correct function of the Zn layer it is important to abide the prescribed thickness. In the electroplating shop the thickness of Zn layer is usually measured by magnetic-inductive method. This method is fast, simple and non-destructive. The aim of this work is to verify the accuracy of this method using optical microscopy. Optical microscopy is here understood as the reference method, because this method is accurate and correct.
While dealing with the given problems the statistical tests shown, that the differences between the results of the two methods are statistically significant. Therefore results of magnetic-inductive method must be corrected using the calculated conversion factor. After conversion of the measured values the magnetic-inductive method can be recommended to operating measurement of the Zn layer thickness on unalloyed and low-alloyed steels. Furthermore, it was found that the type of final surface treatment (chromate surface coating) does not affect accuracy of measurement of Zn layer.