Background: Collagen-based scaffolds are widely used in regenerative applications, where their structural organization and physicochemical stability are essential for clinical performance. This study aimed to evaluate the influence of hydration on the thermal behavior and microstructural characteristics of a collagen-based matrix (Mucoderm®, Botiss Biomaterial GmbH, Zossen-Germany). Methods: Differential scanning calorimetry (DSC) was used to investigate thermal transitions in dry and rehydrated samples, while scanning electron microscopy (SEM) coupled with energy-dispersive spectroscopy (EDS) was employed to assess surface morphology and elemental composition; Results: The dry sample exhibited a broad endothermic transition at 87.8 °C, which shifted to higher temperatures upon rehydration, reaching 103.5 °C and 112.4 °C after 15 and 30 min, respectively. A corresponding increase in enthalpy values was also observed. SEM analysis revealed a heterogeneous surface morphology characterized by alternating compact and less dense regions, while EDS confirmed the predominance of carbon and oxygen with minor elements present in trace amounts; Conclusions: These findings indicate that hydration influences both the thermal response and structural organization of the scaffold, highlighting the role of water-matrix interactions in determining its physicochemical behavior.

Cr2O3-based ceramic coatings are widely used in wear-critical applications; however, their tribological performance under dry sliding conditions can be limited by brittleness and frictional instability. In heavy-duty vehicles, the king pin–bushing contact operates under severe dry sliding conditions, motivating the investigation of composite Cr2O3–nTiO2 coatings as a potential surface engineering solution. In this study, Cr2O3–TiO2 coatings containing 0, 10, 20, 30, and 40 wt% TiO2 were deposited by atmospheric plasma spraying (APS) from mechanically mixed powders. Phase composition was analyzed by X-ray diffraction using an X’Pert PRO MRD diffractometer, while microstructure and elemental distribution were examined by scanning electron microscopy (SEM) coupled with energy-dispersive X-ray spectroscopy (EDS) on a FEG Quattro C microscope. Mechanical properties were evaluated by Vickers microhardness, instrumented indentation and scratch testing, while dry sliding wear behavior was assessed by pin-on-disc tests performed on a CETR UMT-2 tribometer against a bronze counterbody, with continuous monitoring of the coefficient of friction (COF). The results show that plasma spraying produces lamellar composite coatings with intrinsic porosity and locally modified phase composition. Cr2O3-rich coatings exhibit higher hardness (1198 HV2 compared with 877 HV2 for Cr2O3–40TiO2 corresponding to an increase of approximately 36%) and improved resistance to indentation, reflected by lower penetration depths and higher elastic modulus values (134 GPa for S0 compared with 77 GPa for S2). These coatings also exhibit a more stable friction response and reduced material transfer from the bronze counterbody, as confirmed by the lower mass loss of the pins (0.0295 g for S0 compared with 0.0473 g for S4, corresponding to a reduction of about 38%). Increasing TiO2 content leads to changes in friction stability and wear behavior associated with microstructural heterogeneity. These findings indicate that the sliding wear performance of Cr2O3–nTiO2 coatings is governed by elastic–plastic stability under localized contact loading and support their applicability for dry sliding king pin–bushing systems in heavy-duty vehicles.

Low-emissivity (low-E) coatings are among the most effective thin-film technologies for reducing radiative heat losses and controlling solar heat gain in buildings, which account for approximately 30–40% of global primary energy consumption. This expanded review follows the technological evolution of low-E glazing from early transparent-conductor “heat mirrors” to modern multi-silver dielectric/metal/dielectric (D/M/D) architectures and emerging functional coatings. Four complementary perspectives are addressed: (i) the materials employed, from silver-based multilayers and transparent conducting oxides (ITO, FTO, AZO, GZO) to seed, blocker, and protective dielectric layers; (ii) the deposition systems, contrasting on-line pyrolytic/CVD “hard” coatings with off-line magnetron-sputtered “soft” coatings, together with ALD, sol–gel, and evaporation routes; (iii) the methods of analysis used to correlate microstructure, composition. and interfaces with optical, electrical, and thermal behaviour (XRD, XRR, SEM/TEM, AFM, XPS, SIMS, spectrophotometry, ellipsometry, emissivity, and U-value metrology according to EN 410/EN 673 and ISO 9050); and (iv) the functional performance of low-E stacks in insulating glass units, vacuum glazing, retrofit films, and smart-window systems across climate zones. Persistent research gaps are identified in long-term durability and ageing, indium-free scalable materials, standardized accelerated testing, and multi-objective design of thinner, more selective, and more robust stacks.

Atmospheric Plasma Spray (APS) coatings have earned a well-deserved place in the category of thermal spray coatings over the last decades, as they have brought coatings made of ceramic materials to the forefront. This has greatly extended the range of applications of these coatings, ranging from improved wear resistance to enhanced resistance to use at very high temperatures. In this study it is analyzed how two thermally sprayed Cr2O3-based coatings, a 99wt% Cr2O3 powder and a Cr2O3-10wt%TiO2 powder, were affected by exposure to thermal shock, with temperatures recorded in the range of 700 to 900°C. The samples were analyzed by scanning electron microscopy and EDS analysis (Energy Dispersive Spectroscopy), the results being completed by roughness measurements on the affected areas using a Mahr perthometer and AFM (Atomic Force Microscopy). No major changes were observed in the comparative behavior of the two coatings, nor in comparison with the material not affected by thermal shock, both in terms of morphology and chemical composition of the areas subjected to thermal shock, as well as their roughness or compactness. It can thus be concluded that the presence of a small percentage of TiO2 does not negatively influence the thermal shock behavior of this type of coating, and the range of applications can be extended to high temperatures.

Due to the low hardness of carbon steels, their low resistance to wear, and erosion by cavitation and corrosion, it is necessary to protect the surfaces of parts with layers capable of ensuring the properties listed above. In this paper, we started from the premise that adding tungsten carbide (WC) powders during the electric arc spraying process of stainless steel would lead to obtaining a composite material coating resistant to wear and erosion at high temperatures, with relatively lower manufacturing costs. Thus, our research compared the following two types of coatings: a highly alloyed layer with WC, Cr, and TiC (obtained from 97MXC core wires) and a 60T/WC coating (obtained from a 60T solid-section wire to which WC was added), in terms of microstructure, mechanical properties, dry friction wear, and behaviour at erosion by cavitation (EC). The results of our research demonstrated that although the 60T/WC coating had lower erosion by cavitation behaviour than the 97MXC one, it can still be considered as a relatively good and inexpensive solution for protecting C15 steel parts.

The high yttria content of a stabilized zirconia (YSZ) (38 wt% Y2O3) coating was deposited by atmospheric plasma spraying (APS) from Metco 207 powders on an Inconel 718 (Ni-based superalloy) substrate. As a metal coating connection, a layer of cermet powder (Ni-20% Al—410NS) was used before the ceramic layer deposition. The electro-chemical corrosion resistance of these materials was tested using Inconel cylinders with a diameter of 10 mm and a thickness of 1 mm, with and without the ceramic layer. Linear and cyclic measurements were obtained in H2SO4 electrolyte media at pH = 2. Electro-impedance spectroscopy (EIS) experiments were performed on the sample covered with the ceramic layer to evaluate the interface behavior. Scanning electron microscopy (SEM), along with equipment to determine chemical composition, and an energy dispersive spectrometry (EDS) detector were used to characterize the material surface before and after corrosion tests. It was observed that the corrosion resistance of Inconel was influenced by the bonding layer and the ceramic coating.

This paper presents a comprehensive analysis of recent advancements in the application of thermal spraying techniques to enhance the durability and wear resistance of agricultural machinery components, with a particular focus on disc harrow assemblies. Given the harsh conditions under which tillage tools operate—characterized by abrasive wear, impact stresses, and chemical exposure from various soil types—thermal sprayed coatings have emerged as a viable solution to extend the service life of these components. The study discusses various deposition methods, particularly Atmospheric Plasma Spraying (APS), and evaluates their effectiveness in creating high-performance surface layers that resist wear, corrosion, and mechanical degradation. The review also summarizes experimental and field test results for coatings based on materials such as NiCrBSi, WC-Co-Cr, TiO2, Al2O3, Cr2O3, and ceramic–metal composites, highlighting their significant improvements in hardness, friction reduction, and resistance to delamination and oxidation. The paper highlights research using thermal spraying techniques, especially APS for agricultural applications, with emphasis mostly on components intended for soil processing and requiring good resistance to abrasive wear.

Thermal barrier coatings (TBCs) can be applied on the inner surface of the combustion chamber of internal combustion engines to reduce fuel consumption and pollution and also improve the fatigue life of their components. The purpose of the present work was to evaluate the corrosion resistance in an environment equivalent to the one generated by combustion gases for three types of TBCs—P1 from Cr3C2-25(Ni20Cr), P2 from MgZrO3-35NiCr and P3 from ZrO2-5CaO—with all of them having a base coat from Al2O3-30(Ni20Al) powder. The coatings were deposited via atmospheric plasma spray (APS) on the intake/exhaust valves of a gasoline internal combustion engine, both before and after their use in operation (Dacia 1400 model, gasoline fuel, Dacia Company, Mioveni, Romania). The samples were studied from the electrochemical corrosion resistance point of view, and their morphology and structure were analyzed using SEM, EDS and XRD methods. After analyzing the results of the samples before and after testing them in operation, it was observed that the presence of the coatings improved the corrosion resistance of the material used for the production of the valves.

Chromium carbide powders are widely used for thermal spray coatings because these hard particles provide improvements of mechanical properties, mainly wear resistance, on the surfaces on which they are deposited. The integration of chromium carbides in a Ni-based matrix provides increased erosion, abrasion, hot wear and corrosion resistance. In this paper, a comparative study is presented between two types of chromium carbide-based coatings made by two different spray deposition methods, namely atmospheric plasma spray (APS) and cold spray (CS). By electron microscopy (SEM) and X-ray diffraction (XRD) analysis, the effect of the deposition technology on the morphology of the coatings and especially on the way chromium carbides are embedded in the deposited layers was analyzed. It was observed that plasma spraying is accompanied by phase transformations of the chromium carbides (e.g. Cr7C3 type carbides appear), which can increase the hardness of the coating thus obtained, but also by the appearance of oxides of the component elements (NiO, Cr2O3, NiCr2O3). By comparison, cold spray coating provides a compact coating with minimal oxidation, which is the main advantage of this deposition technology.

Fulfilling the basic role of hard thermal sprayied coatings is closely related to the value of its microhardness. The quality of such a layer depends on several variables, the main categories being: spray method (flame spray, electric arc, plasma spray, cold spray, etc.), spray parameters (spray distance, voltage and intensity, working atmosphere, direction of the spray jet, etc.) and the materials used (chemical composition of the coating materials, quality and texture of the substrate). In this study, the microhardness, elastic properties and cohesion of a coating made of hard cored wire (Praxair – Tafa) by electric arc spraying process on a low alloy steel substrate, were analyzed. The cored wire has as main hard elements WC (about 26%) and TiC (about 6%), the rest of the chemical elements present being: Cr (14%), Ni (4.5%), B (1.87%), Si (1.25%) and the Fe balance. The micro-hardness was evaluated onto the surface of the coating, previously prepared by grinding to reduce the as-coated roughness. The method based on recording the forcess generated during the indentation with simultaneous measurement of the load – depth curve (with UMT 2MCETR microtribometer) were used for the microhardness evaluation. In order to analyse the cohesion of the coated layer, scratch tests with progressive loading (10N, 15N and 20N) were performed on the same microtribometer. Tests have shown that the metal matrix uniformly includes the hard particles arised from the core of the wire, and at the microstructural level, the microhardness varies significantly, depending on the hardness of the particles on which the indentor tip applies the loading forces. However, the overall behavior of the coatings thus realized is a satisfactory one, being, as a general behavior, in the average required by the applications of such a layer.

In this article, the case of depositing a Ni-based alloy layer by thermal arc spraying on a copper alloy substrate with cylindrical geometry over its entire surface is presented. After the coating was deposited, the layer was analyzed microstructurally both on the surface and in cross-section, and it was observed that it adhered very well to the substrate. In addition to the high adhesion to the substrate, a low porosity of the coating was observed, which ensures good compactness of the coating. Based on these results, further investigation of the Ni coating can be recommended to limit the toxicity caused by the oxidation of copper and copper alloy heating elements.

Ceramic materials as coatings are known to have very good corrosion resistance properties compared to metallic or organic coatings, regardless of environmental conditions. The following samples were used for the experiments: an initial steel substrate and Al2O3 + YSZ (12.5%; 25% and 37.5% wt) atmospheric plasma spray-coated samples. The open circuit potential showed similar average values for all samples coated with ceramic layers, which were slightly higher than the potential of the original uncoated sample. The corrosion current densities (icorr) of all plasma jet sputter-coated systems were very similar and significantly lower than those of the original material. Corrosion rates were much lower in the coated systems due to the chemical inertness of the ceramic coatings, particularly alumina- and zirconia-based coatings. It was observed that ceramic layers improve the corrosion resistance of the metallic material, especially at higher percentages of YSZ in the plasma spray-deposited complex layer. The porosity of the sputter-deposited layers reduced their corrosion resistance due to the contact between the electrolyte solution and the metal substrate created by the interconnection of the pores. The complex equivalent electrical circuit chosen for the analysis of the values led to results in accordance with the experimental parameters.

In the Cold Spraying technology, the coatings are produced as a result of the supersonic acceleration of the particles in a gas jet, at temperatures below the melting/phase transformation point of the sprayed material. In this paper, the morphology of a Ni/CrC cold spray coating is studied, based on the identification of the particle’s characteristic at various magnifications, both on cross-section and on the surface of the samples. The layer appearance is continuous, uniform and sinuous, no adhesion defects were observed at the substrate-coating interface, and the plastic deformation of the steel was highlighted. The elemental chemical analysis on the sample cross-section, together with the distribution map shows that the carbide particles have retained their sphericity to a large extent, being uniformly embedded in the Ni matrix, as a result of the plastic deformation. This allows a higher thickness of the cold spray coatings comparatively to the ones obtained with the other thermal spray methods that imply high temperatures of the gas jet and layered microstructures.

Copper metal powder being highly thermally and electrically conductive. It has a lot of uses such as: manufacture of soft magnets, sintered components, friction products, surface coating etc. This publication examines the properties of biodegradable polymers (PLA and HD PLA Green) coated with two different bronze alloy powders, Metco 51F-NS (Cu 9.5Al 1.2Fe) and Metco 445 (Cu 9.5Al). The coating was applied to printed samples using the Atmospheric Plasma Spray (APS) process. This inquiry will elucidate the findings concerning surface quality, microstructure, microindentation, and scratch testing. The outcomes of micro indentation and scratch analysis were markedly affected by the semicrystalline structure of the samples and the presence of powder components. The authors of this research assert that components fabricated from biodegradable polymers and coated with copper micro-particles are suitable for certain applications necessitating rigorous operating conditions, given the enhanced properties of the coated samples.

In this paper we studied how alloying with different percentages of TiO2 influences the microstructure of Cr2O3 base matrix coatings deposited by plasma spray (APS). Thus, five different types of coatings were made, in which the percentage of TiO2 varied as 0%, 10%, 20%, 30% and 40%. The samples were analysed morphologically both on the surface and in cross-section using direct observation and electron microscopy (SEM). It was observed that none of the TiO2-containing coatings is a simple blend of distinct phases, but are coatings with a specific layered lamellar structure, with coarser and smooth areas, depending on the Ti wt.% presence. All the coatings analysed show micro cracks, porosities and inhomogeneous structure, but with a higher density directly proportional to the percentage of TiO2 in the composition of the coated powder.

3D printing is a technology used on an ever-increasing scale, which makes it easier to obtain parts with complex geometry. The printing process is very complex because, in addition to the variables introduced by the various materials that are used, there is a multitude of process parameters: printing direction, layer thickness, infill level, filament feed rate, printing temperature, printing bed temperature, etc. Each process parameter influences the mechanical properties of the 3D-printed structure, which is why it is necessary to define the range of possible values where the effect is maximum. In this paper it was studied the effect of process parameters variation on the roughness and mechanical properties of the 3D-printed samples. Using a commercially PLA filament (produced by Prussia), we made six sets of 3D-printed samples, using six different overflow (OF) values: 90%, 95%, 100%, 105%, 110%, 115%. The test samples (realized according to ISO 572-2) were subjected to tensile tests on an Instron 3382 machine, and the results were interpreted comparatively. It has been observed that there are variations of the mechanical properties, dependent on the chosen values of the overflow and, in addition, this process parameter has an important role for the achieving the desired structure.

In this paper, the effect of two process parameters on the mechanical properties of tensile specimens made by FDM was studied. A commercially available PLA filament (produced by Prusa) was used as raw material, from which several sets of specimens were produced, the varied parameters being the raster angle (RA) relative to the longitudinal axis of the specimen and the overflow (OF). Thus, three printing angles were chosen, 0 degrees, 22.5 degrees and 45 degrees, each set of specimens being made with an OF of 95%, 100% and 105% respectively. The printed layer was chosen with a standard thickness of 0.2 mm. For the analysis of the mechanical properties, the specimen sets were subjected to tensile testing on an Instron 3382 machine and the results obtained were interpreted comparatively. Additionally, the fracture surfaces of the specimens were analysed by stereomicroscope. Two-way repeated measures ANOVA analysis of experimental data indicated that both parameters and their interaction significantly influence the specimen weight but, in the case of mechanical properties (modulus of elasticity, yield strength, tensile strength, yield elongation and tensile elongation) were insignificantly influenced by both process parameters. In this context regardless of raster angle, an overflow of 95% provides the same mechanical properties as an overflow of 105%, but at a minimum weight sample.

The mechanism in which the coatings made by thermal spraying adhere to the substrate is in most cases of a mechanical nature, thus being dependent on the morphology of the substrate surface. This paper study how the texture of the substrate influences the behavior of dry sliding wear, a behavior based on the adhesion to the substrate of the analyzed coatings. For this purpose, a Co – base powder, was chosen for atmospheric plasma spraying. For the substrate, a rectangular profile made of low-alloy steel was chosen, the surface of which was textured by mechanical abrasion, in order to obtain different degrees of roughness: sample S1 – Ra1 = 1.59 µm, sample S2 – Ra2 = 2.32 µm, sample 3 – Ra3.1 = 1.25 μm, Ra3.2 = 3.88 μm. In the case of sample 3, the texturing was done on one direction, with an elongated profile, so that the effect of the main direction of dry sliding wear on the quality of the coating could be studied. The tests were performed on an Amsler test machine, at constant load, for 1 hour. The samples were mounted in a fixed position, and the wear occurred on the basis of the rotation of the metal disc, without lubrication. It was found that the coating of sample 1 was the most affected, resulting even a partial delamination, and the best behavior was recorded in the case of sample 3.1.

"Abrasion wear is one of the most dominant types of wear in many applications, causing over 50% of all wear failures [1]. The abrasive wear phenomenon could be classified regarding several aspects: a) the position of the abrasive particles: two-body abrasion if they are fixed, or three-body abrasion if they are free to slide and/or roll, b) the stresses involved: gouging abrasion, high-stress abrasion (grinding) and low-stress abrasion (scratching), c) the surface appearance: ploughing, cutting, fatigue and fracture (cracking). In this study was approached the possibility of abrasion wear resistance evaluation of selffluxing Ni-base coatings by scratch testing. Materials used in tests were: three self-fluxing Ni-base coatings deposited on low-alloyed steel substrate using flame spraying process (referred to as S1, S2 and S3). The wear of the samples and the friction coefficient were investigated with scratch tester and analyzed in correlation with their mechanical properties. "

The alkaline extraction of hemicelluloses from a mixture of three varieties of wheat straw (containing 40.1% cellulose, 20.23% xylan, and 26.2% hemicellulose) was analyzed considering the following complementary pre-treatments: freeze–thaw cycles, microwaves, and ultrasounds. The two cycles freeze–thaw approach was selected based on simplicity and energy savings for further analysis and optimization. Experiments planned with Design Expert were performed. The regression model determined through the response surface methodology based on the severity factor (defined as a function of time and temperature) and alkali concentration as variables was then used to optimize the process in a multi-objective case considering the possibility of further use for pulping. To show the properties and chemical structure of the separated hemicelluloses, several analytical methods were used: high-performance chromatography (HPLC), Fourier-transformed infrared spectroscopy (FTIR), proton nuclear magnetic resonance spectroscopy (1H-NMR), thermogravimetry and derivative thermogravimetry analysis (TG, DTG), and scanning electron microscopy (SEM). The verified experimental optimization result indicated the possibility of obtaining hemicelluloses material containing 3.40% glucan, 85.51% xylan, and 7.89% arabinan. The association of hot alkaline extraction with two freeze–thaw cycles allows the partial preservation of the hemicellulose polymeric structure.