Solid State Phenomena Vol. 237

Abstract: The work presents studies of a new ceramic-metallic material. The base is a ZrO₂-Mo cermet which is modified with metallic Mo or Mo85Re15 alloy coating. The structure and microstructure of Mo85Re15 alloy powders and the composite were characterized. The annealing procedure was found to influence phase composition of powder composites but not their morphology. The plasma sprayed powders, both metallic and alloyed, form coatings that adhere well to the cermet substrate. The coatings show a better homogeneity in comparison to powders and more favourable phase composition.Keywords: cermets, plasma spraying, corrosion resistance

Abstract: One of the areas in which increased durability is of particular significance is the use of machine elements in conditions of intensive exposure to erosive wear, for example, turbine blades of aircraft engines and power turbines in ventilation systems, and machine elements working in a dusty environment. As it is apparent from the analysis of the state of the art, high possibilities to increase the erosive and abrasive wear resistance of machine elements are created by appropriately designed coatings and layers, especially multilayer coatings composed on the base of materials with different plasticity properties. This is associated with particular characteristics of this type of multilayer coatings that allow the absorption of external energy reaching the surface without causing permanent damage to the coating, while significantly reducing the erosive wear rate.The article presents the results of material research and the results of erosion test of three different materials solutions of surface engineering, i.e. multilayer coatings (Cr / CrN) x8, (TiN / ZrN)_multinano and a (Ti-Al) _{intermetallic} / AlCrTiN hybrid layer, obtained on titanium alloy Ti6Al4V. The (Cr / CrN) x8 and (TiN / ZrN)_multinano multilayer coatings were obtained by arc evaporation, and the (Ti-Al) _{intermetallic} / AlCrTiN hybrid layer was prepared using a hybrid technology combining diffusion saturation in aluminium powders and arc evaporation in a single technological process. The selected material solutions of the surface layer were subjected to the analysis of the structure by scanning electron microscopy (Hitachi 3000). Measurements of hardness and Young's modulus were conducted using the nanohardness Tester CSM. The results of this study allowed the authors to compare the erosive wear resistance and wear resistance of selected material solutions, and this led to the conclusion that the (Ti-Al) _{intermetallic} / AlCrTiN hybrid layer is the most effective solution.

Abstract: Based on the analysis of the research directions in the field of coatings and layers with special operating properties, the production technologies of composite coatings, including the gradient, multi-layer, and multi-component coatings, should be distinct. The paper presents the results of material properties tests of a multi-layer coating Ti / TiN / TiAlN_gradient / (TiAlN/VN)_multinano obtained on hot working steel EN X32CrMoV3.3. The preparation of the multilayer coating was specially designed to increase the durability of forging dies in the brass forging process. The authors discuss the results of the microstructure tests for the obtained coatings (STEM+FIB) and present the hardness and Young's modulus as a function of the distance from the surface (nanoHardness Tester CSM) and the results of adhesion tests carried out using a scratch-test method. The obtained multilayer coatings were also subject to a tribological test using a tribometer tester by DUCOM. The authors indicate that the coatings based on vanadium nitride have very high hardness and Young's modulus (HV = 32–35 GPa, E = 420–450 GPa), a much lower coefficient of friction in combination with brass than steel, and a lower stability of these parameters at elevated temperatures. According to the authors, the coating represents an interesting material solution to increase the durability of forging dies in the process of brass forging.

Abstract: The research on erosion resistance can be classified into two groups, i.e. standardized research, conducted with specific parameters of the test and dedicated to commercially available products, and experimental studies whose the aim is to investigate different mechanisms of erosion (e.g. micro-cutting, the formation of grooves, fatigue wear, and cracking and chipping of brittle materials) with different parameters of the process, i.e. the angle of impact of the particles, the speed and particle size, the particle temperature, and the temperature of the eroded material. Devices available on the market allow the implementation of erosion tests in accordance with the requirements of the standards. Experimental studies are carried out exclusively on laboratory equipment with incomparable characteristics. The Institute for Sustainable Technologies - National Research Institute in Radom designed and produced a universal testing device enabling investigations both in accordance with the requirements of the applicable standards: ASTM-G76, PN-76/C-81516, PN-EN ISO 16282, as well as experimental research. The device enables the execution of experiments in a wide range of parameters relevant to the processes of erosion, i.e. temperature (≤ 600 °C), the angle of the sample relative to the abrasive particles (25^o to 90^o), the speed of abrasive particles (10 to 130 m/s) and abrasive particles flow (2 to 10 g / min). In the paper, the authors described the construction of the device and the reported ranges of the erosive wear test parameters and presented examples of the results of tests for selected solid materials and selected coatings produced by PVD methods.

Abstract: One of the most effective ways of shaping the operating parameters of functional elements is to modify the properties of a surface layer using modern technologies of surface engineering. The prospective directions in the development of surface engineering solutions are nanomultilayer coatings that enable effective shaping of surface layer properties. A very important factor in designing properties of PVD coatings, apart from their chemical composition, is their microstructure.The paper presents the influence of the microstructure of the nanomultilayer AlN-CrN-TiN coating on their tribological properties at elevated temperatures. The research methods were concentrated on the analysis of mechanical properties, microstructure, and tribological properties at increased temperatures. The studies on mechanical properties included tests on hardness using the nanoindentation method and tests on adhesion using the scratchtest method. The analysis of microstructure was performed using scanning microscopy. The tribological properties at high temperature were examined using the ball-on-disc method. The authors indicate that the AlN-CrN-TiN layers are characterised by excellent mechanical properties and tribological resistance. In this paper, the authors confirm that the microstructure of a nanomultilayer coating is important in shaping the mechanical and tribological properties of a PVD coating.

Abstract: The paper presents the results of tests on an “intermetallic layer TiAl / coating AlCrTiN" hybrid layer, which was obtained using a hybrid method combining magnetron Sputtering, diffusion, and arc evaporation in a single technological process. The hybrid layer obtained was subjected to studies on morphology and chemical composition using the TM3000 scanning electron microscope. Additionally, hardness and Young's modulus as a function of distance from the surface were measured using a nanohardness tester CSM. Based on the analysis of the results obtained, the authors suggest the mechanism of layer growth in the technological process. The composite layer was also subjected to wear resistance using the ball-cratering method and erosion resistance tests using the glass powder. The obtained results showed that the Ti-Al _{intermetallic} / AlCrTiN hybrid layer significantly increases resistance to abrasion as well as erosion wear resistance of the Ak12 alloy.

Abstract: The paper describes the optimization procedure supporting the designing process of geometry of gradient coatings basing on numerical simulation of internal stress and strain distributions in the coating and substrate. In mathematical model the gradient coating is represented by the so-called transition functions describing the change of physico-chemical parameters such as Young's modulus, Poisson's ratio, thermal expansion coefficient and the density as a function of the spatial variables. The object of optimization is system composed of a CrN/CrCN gradient coating and Cr interlayer between the CrN /CrCN coating and the steel substrate deposited on nitrided 4140 steel substrate. Decision variables are: the parameters of the of curvature of transition function , thickness of gradient coating and the thickness of the Cr interlayer. Optimization was carried out under pre-defined fixed continuous external loads and created decision criteria were the functions of the state of stress and strain in the coating and the substrate. Using the optimization procedure the sets of optimal parameters (Pareto sets) of the PVD gradient coating/nitrided substrate systems, due to the adopted decision criteria were determined. The analysis of the obtained optimal solutions (Pareto-optimal sets) was carried out using the "utopian solution method". It was also examined the technological stability of the Pareto-optimal solutions (nondominated) by analyzing the number of direct neighbors of these solutions in the decision variables space.

Abstract: The aim of this work was to investigate thermal stability and corrosion resistance of the Cr/CrN multilayer coatings. For this purpose, multilayer Cr/CrN coating was deposited on Ti6Al4V titanium alloy using PVD vacuum arc method. The Cr/CrN coating has thickness of 5.6 μm and was composed of 16 layers (8 Cr and 8 CrN). The Cr layers has thickness of 0.26 μm and were composed of columnar grains. CrN layer has thickness of 0.32 μm and were characterized by needle-like structure. Because of the potential application of the investigated coatings, thermal stability in temperature range of 300-500°C as well as corrosion behavior during salt fog test were analyzed.The investigation showed that microstructure of Cr/CrN multilayer coating was stable up to 400°C. In this temperature only a slight increase of thickness of transition Cr₂N layer was observed. Annealing at temperature of 500°C changed the microstructure of the constituent Cr and CrN layers and caused decrease of their thicknesses due to increase of thickness of Cr₂N transition layer. Annealing at 500°C also increased the hardness of Cr/CrN coating. XPS analysis revealed the presence of the CrO₃ and Cr₂O₃ on the surface after annealing. Cr/CrN multilayer coatings exhibit also excellent corrosion resistant in salt fog test. No corrosion products was observed on the Cr/CrN coating surface after 120 hour of test.

Abstract: Advanced surface engineering technologies are the basis of the intense technological development in the world over the past several decades. The rapid development of surface engineering resulted in the appearance of many new top layer solutions, such as multi-layer coatings, nanostructured coatings, and hybrid layers, which prove to be very effective in their applications. The production of layers and coatings with complex microstructure and application requirements (related to coated materials, the geometry of the engineered elements, economic viability) create a need for advanced technological and organizational solutions.This article presents a technology of manufacturing a hybrid layer: “nitrided layer + (Cr/CrN) _multilayer,” intended to increase the durability of hot forging dies. Based on this example, those surface engineering fields are presented where simultaneous intensive development is necessary to ensure an efficient process of transferring innovative surface engineering solutions to the industry.