Search

In the present work, the results of studies on the structure and corrosion resistance of Al(Co, Ni) layer are shown. The diffusion Al(Co, Ni) layer was created on the cobalt alloy Mar-M-509 substrate by chemical vapor deposition (CVD) method with aluminum trichloride (AlCl3) under the hydrogen atmosphere. The scanning electron microscope (SEM) observations and microtomography measurements of layers were performed. Also an analysis of the chemical (energy-dispersive X-ray spectroscopy (EDS)) and phase (X-ray diffraction (XRD)) composition was carried out. By the X-ray diffraction method (sin2 φ) also the residual stresses were calculated in the matrix of the material. The corrosion resistance was tested with impedance and potentiodynamic methods in 0.1 M Na2SO4, 0.1 M H2SO4 solutions and acidulous 0.1 M NaCl solution (pH = 4.2) at room temperature. The results indicate that the analyzed layer with a thickness of about 14 μm have a similar corrosion resistance compared to the base material - Mar-M-509® cobalt alloy. Only in the strongly acidic environments, the corrosion resistance of the layer is remarkably decreased. [ABSTRACT FROM AUTHOR]

In the present work, the results of studies on the structure and corrosion resistance of Al(Co, Ni) layer are shown. The diffusion Al(Co, Ni) layer was created on the cobalt alloy Mar-M-509 substrate by chemical vapor deposition (CVD) method with aluminum trichloride (AlCl3) under the hydrogen atmosphere. The scanning electron microscope (SEM) observations and microtomography measurements of layers were performed. Also an analysis of the chemical (energy-dispersive X-ray spectroscopy (EDS)) and phase (X-ray diffraction (XRD)) composition was carried out. By the X-ray diffraction method (sin2 φ) also the residual stresses were calculated in the matrix of the material. The corrosion resistance was tested with impedance and potentiodynamic methods in 0.1 M Na2SO4, 0.1 M H2SO4 solutions and acidulous 0.1 M NaCl solution (pH = 4.2) at room temperature. The results indicate that the analyzed layer with a thickness of about 14 μm have a similar corrosion resistance compared to the base material - Mar-M-509® cobalt alloy. Only in the strongly acidic environments, the corrosion resistance of the layer is remarkably decreased. [ABSTRACT FROM AUTHOR]

The paper presents results of studies of structure and properties of the NiAl + FeAl type diffusion layers fabricated on 316L steel (00H17N14M2) by the chemical vapour deposition using aluminium chloride (AlCl3) in a hydrogen atmosphere as a carrier gas. The layers were examined using light and scanning electron microscopy. Chemical composition analyses were carried out by EDS and phase content was investigated by XRD. Corrosion resistance was tested using the potentiodynamic method in 0.5 M NaCl, and layer/structure adhesion was tested by the scratch test. The results obtained indicate that the 50 µm thick layers fabricated on the 316L steel substrate show very good adhesion combined with very good corrosion resistance. [ABSTRACT FROM AUTHOR]

The paper presents the results of examinations of the structure and properties of Al2O3 + Ni3Al + Ni(Cr, Fe, Al) + Cr-Ni + Cr7C3 multilayers produced on nickel alloys by the plasma assisted chemical vapour deposition method with the participation of trimethylaluminum vapours in gaseous atmosphere. The layers have a high surface hardness of about 1200HV0.05, and high heat and frictional wear resistance. In order to find a correlation between the structure of the multilayers and their properties, the following examinations have been executed: phase analysis by XRD and surface analysis by XPS, analysis of microstructure by optical and scanning electron microscopes as well as X-ray microanalyser, micro-hardness measurements, corrosion and frictional wear resistance testing. [ABSTRACT FROM AUTHOR]

The results of experimental and numerical studies of plastic forming of sheets made of the difficult-to-deform Hastelloy X, a nickel-based alloy with a thickness of 1 mm, using layered elastomeric punches and steel dies, are presented in this publication. The elastomeric punches were characterized by hardness in the range of 50-90 Shore A, while the dies were made of 90MnCrV8 steel with a hardness of over 60 HRC. The principle of operating the stamping die was based on the Guerin method. The finite-element-based numerical modeling of the forming process for various configurations of polyurethane inserts was also carried out. The results obtained from numerical modeling were confirmed by the results of experimental tests. The drawpieces obtained through sheet forming were subjected to geometry tests using optical 3D scanning. The results confirmed that in the case of forming difficult-to-deform Hastelloy X, Ni-based alloy sheets, the hardness of the polyurethane inserts significantly affected the geometric quality of the obtained drawpieces. Significant nonuniform sheet metal deformations were also found, which may pose a problem in the process of designing forming tools and the technology of the plastic forming of Hastelloy X, Ni-based alloy sheets.

This article presents the results of testing the suitability of X-ray computed tomography for the quality control of the casting moulds used for producing turbine blades. The research was focused on the analysis of cross-sectional images, spatial models and the porosity of moulds using a Phoenix L 450 microtomograph. The research material consisted of samples from three mixtures of ceramic materials and binders intended for producing casting moulds using the lost wax method. Various configurations of filling materials (Molochite and quartz flours) and binder (Remasol, Ludox PX 30 and hydrolysed ethyl silicate) mixtures were considered. X-ray computed tomography enabled the detection of a number of defects in the ceramic mass related to the distribution of mass components, porosity concentration and defects resulting from the specificity of the mould production. It was found that casting mould quality control on cross-sectional tomographic images is faster and as accurate as the analysis of three-dimensional models and allows for the detection of a whole range of ceramic defects, but the usefulness of the images is greatest only when the cross-sections are taken at an appropriate angle relative to the object being examined.

This study presents a comparative analysis of the corrosion resistance of nitrided layers on conventional Grade 2 titanium alloy and those produced by direct metal laser sintering (DMLS). Low-temperature glow-discharge nitriding of the tested materials was carried out using conventional glow-discharge nitriding (so-called nitriding at the cathode potential-TiN/CP) and with the use of an "active screen" (nitriding at the plasma potential-TiN/PP). The TiN + Ti 2 N + Ti(N) layers were characterized by their microstructure, nanohardness profile distribution, surface topography, and corrosion resistance. The reduction in the cathodic sputtering phenomenon in the process using the active screen allowed the creation of surface layers that retained the topography of the base material. The parameters of the glow-discharge treatment led to grain growth in the printed substrates. This did not adversely affect corrosion resistance. The corrosion resistance of nitrided layers on the printed titanium alloy is only slightly lower than that of layers on the conventional Grade 2 alloy. Iron precipitates at grain boundaries facilitate increased nitrogen diffusion, resulting in reduced nitrogen concentration in the surface layer, slight changes in corrosion potential values, and increased nitrogen concentration in the Ti(N) diffusion layer.

In this study, we examined the effects of an aluminization process on the microstructure and texture of Haynes 282 nickel samples fabricated using the direct metal laser sintering technique. The aluminization process involved the use of chemical vapor deposition with AlCl 3 vapors in a hydrogen atmosphere at a temperature of 1040 °C for 8 h. Following the 3D printing and aluminization steps, we analyzed the microstructure of the Haynes 282 nickel alloy samples using light microscopy and scanning electron microscopy. Additionally, we investigated the texture using X-ray diffractometry. A texture analysis revealed that after the process of direct laser sintering of metals, the texture of the Haynes 282 nickel alloy samples developed a texture typical of cast materials. Then, in the aluminization process, the texture was transformed-from foundry-type components to a texture characteristic of recrystallization.

The paper investigates the influence of the ion-nitriding process on the microstructure, corrosion resistance, and tensile strength at elevated temperatures of Haynes 282 nickel superalloy specimens produced by the Direct Metal Laser Sintering (DMLS) technique. The study was performed for two conditions, i.e., as-built by DMLS method and as-built by DMLS method + covered by a layer containing CrN + Cr 2 N phases. An analysis of the surface morphology revealed that the ion-nitriding process significantly affects the physical and chemical phenomena occurring on the specimen's surface. The XRD measurement of the specimens showed that preparing them with the DMLS method as well as following a nitriding process produced residual tensile stresses. Based on the measurement of the nanohardness distribution through the layer approximatively of 7 μm in width and the superalloys substrate, the results of the nanohardness showed the maximum values of 27 GPa and 13.5 GPa for the nitrided layer and the substrate, respectively. The surface protection from the nitrided layer proved a positive effect on the corrosion resistance of the DMLS specimens in the solution of 0.1 M Na 2 SO 4 + 0.1 M NaCl at room temperature. The results of the tensile tests at 750 °C showed that the ion-nitriding process did not significantly affect the elevated-temperature tensile strength of the superalloy specimens produced with the DMLS technique.

Interactions in a multicomponent Ni-Cr-Mo-Al-Re model alloy were determined by ab initio calculations in order to investigate the Re doping effect on Haynes 282 alloys. Simulation results provided an understanding of short-range interactions in the alloy and successfully predicted the formation of a Cr and Re-rich phase. The Haynes 282 + 3 wt% Re alloy was manufactured using the additive manufacturing direct metal laser sintering (DMLS) technique, in which the presence of the (Cr 17 Re 6 )C 6 carbide was confirmed by an XRD study. The results provide useful information about the interactions between Ni, Cr, Mo, Al, and Re as a function of temperature. The designed five-element model can lead to a better understanding of phenomena that occur during the manufacture or heat treatment of modern, complex, multicomponent Ni-based superalloys.

The article presents the results of research on the influence of plastic deformation on the microstructure and tensile strength of Haynes 282 nickel superalloy produced by direct metal laser sintering (DMLS) and a conventional technique (casting). Samples were tested for dimensional accuracy using a 3D scanner. Then, the samples were subjected to plastic deformation by rolling. The microstructures of the DMLS and the as-cast samples were analysed using a scanning electron microscope. The strength properties of the samples were determined in a static tensile test. Microhardness measurements of the samples were also performed. Based on the analysis of the dimensional accuracy, it was found that the surface quality of the components produced by DMLS is dependent on the input parameters of the 3D printing process. Using the DMLS method, it is possible to produce Haynes 282 with a fine-crystalline microstructure containing dendrites. The fine-crystalline dendritic microstructure and low porosity showed very good tensile strength compared to the as-cast material. It was also found that the increase in the degree of plastic deformation of the as-cast Haynes 282 and the samples produced by the DMLS technique resulted in an increase in the strength of the tested samples, with reduced ductility., Competing Interests: The authors declare no conflict of interest.

This article presents the results of research on the use of modern nondestructive methods such as 3D scanning, thermography and computed tomography (CT) to assess the quality of multilayer ceramic molds. Tests were performed on spherical samples of multilayer ceramic molds in the raw state. Samples were made of molding sands composed of quartz and molochite powders, the alcoholic binder hydrolyzed ethyl silicate (ZKE) and an aqueous binder based on colloidal silica. Thickness measurements of spherical forms were made using a 3D scanner. Porosity measurements were made using CT. Additionally, thermography observations of the mold cooling process were made with controlled temperature and humidity. The results of temperature measurements of samples were compared with measurements of thickness and porosity. The practical goal was to determine the possibility of using thermography, 3D scanning and CT as a quick method for detecting mold defects by varying their thickness, porosity and cracks and for final verification of the ceramic molds' condition before casting.

In this paper, a novel method for high temperature fatigue strength assessment of nickel superalloy turbine blades after operation at different times (303 and 473 h) was presented. The studies included destructive testing (fatigue testing at temperature 950 °C under cyclic bending load), non-destructive testing (Fluorescent Penetrant Inspection and Eddy Current method), and finite element modelling. High temperature fatigue tests were performed within load range from 5200 to 6600 N using a special self-designed blade grip attached to the conventional testing machine. The experimental results were compared with the finite element model generated from the ANSYS software. It was found that failure of turbine blades occurred in the area with the highest stress concertation, which was accurately predicted by the finite element (FE) model.

The investment casting process is widely used in the aerospace industry to produce complex engine parts. The article determines the properties of quartz powders, nanosilica dioxide binders, and multilayer samples of ceramic casting molds. The properties of spherical molds obtained using an alcohol-water system derived from hydrolyzed ethyl silicate (ZKE) and LUDOX PX-30 (type Q1) were compared with those obtained in water systems derived from Remasol Plus and Remasol Premium binders (type Q2). The spherical samples are composed of seven layers made with the use of an immersion-sprinkling method. To assess the properties of the molds, X-ray microscopy (µCT), scanning electron microscopy (SEM), and gas permeability analysis over a temperature range of 20-950 °C were utilized. The binder type is proven to affect the properties of the casting mold samples. The material obtained in the water system, Q2, has advantageous properties such as a high porosity and gas permeability.

Selective Laser Melting (SLM) is a manufacturing technique that is currently used for the production of functional parts that are difficult to form by the traditional methods such as casting or CNC (Computer Numerical Control) cutting from a wide range of metallic materials. In our study, a mixture of commercially pure titanium (Ti) and 15% at. aluminum nitride (AlN) was Selective Laser Melted to form three-dimensional objects. The obtained 4 mm edge cubes with an energy density that varied from 70 to 140 J/mm 3 were examined in terms of their microstructure, chemical and phase composition, porosity, and Vickers microhardness. Scanning Electron Microscopy (SEM) observations of the etched samples showed inhomogeneities in the form of pores and unmelted and partly melted AlN particles in the fine-grained dendritic matrix, which is typical for titanium nitrides and titanium aluminum nitrides. The AlN particles remained unmelted in samples, but no porosity was observed in the interface area between them and the dendritic matrix. Additionally, samples fabricated with the presintering step had zones with different sizes of dendrites, suggesting a differing chemical composition of the matrix and the possibility of the formation of the phases forming an Ti-Al-N ternary system. The chemical composition in the microareas of the samples was determined using Energy Dispersive X-Ray Spectroscopy (EDS) and revealed differences in the homogeneity of the samples depending on the SLM process parameters and the additional presintering step. The phase composition, examined using X-ray Diffraction analysis (XRD), showed that samples were formed from Ti, TiN, and AlN phases. Porosity tests carried out using a computer microtomography revealed porosities in a range from 7% to 17.5%. The formed material was characterized by a relatively high hardness exceeding 700 HV 0.2 over the entire cross-section, which depended on the manufacturing conditions.

The structure and corrosion resistance of Grade 2 titanium subjected to the hydroextrusion processes were examined. The microstructure was characterized using optical microscopy and transmission electron microscopy. The corrosion resistance was determined using the impedance and potentiodynamic methods, in 0.1 M H2SO4 solutions and an acidified 0.1 M NaCl solution with a pH of 4.2, at ambient temperature. Nanohardness tests were performed under a load of 100 mN. It has been demonstrated that the hydroextrusion method makes it possible to obtain relatively homogeneous nanocrystalline titanium Grade 2 with an increased hardness, the elastic modulus almost unchanged with respect to that of the initial structure and a lower corrosion resistance.