Microstructure and physical properties of black-aluminum antireflective films.

The microstructure and physical properties of reflective and black aluminum were compared for layers of different thicknesses deposited by magnetron sputtering on fused silica substrates. Reflective Al layers followed the Volmer-Weber growth mechanism classically observed for polycrystalline metal films. On the contrary, the extra nitrogen gas used to deposit the black aluminum layers modified the growth mechanism and changed the film morphologies.

Preparation and Characteristics of High-Performance, Low-Density Metallo-Ceramics Composite.

By applying the physical vapour deposition method, hollow ceramic microspheres were coated with titanium, and subsequently, they were sintered using the spark plasma sintering technique to create a porous ceramic material that is lightweight and devoid of a matrix. The sintering process was carried out at temperatures ranging from 1050 to 1200 °C, with a holding time of 2 min. The samples were subjected to conventional thermal analyses (differential scanning calorimetry, thermogravimetry, dilatometry), oxidation resistance tests, and thermal diffusivity measurements.

High-Temperature Corrosion Behavior of Selected HVOF-Sprayed Super-Alloy Based Coatings in Aggressive Environment at 800 °C.

This study is focused on the high-temperature corrosion evaluation of selected thermally sprayed coatings. NiCoCrAlYHfSi, NiCoCrAlY, NiCoCrAlTaReY, and CoCrAlYTaCSi coatings were sprayed on the base material 1.4923.

Hot Corrosion Behavior of TWAS and HVOF NiCr-Based Coatings in Molten Salt.

In order to extend the life of boilers by applying an anti-corrosion coating without the need to dismantle them, it is advisable to find coatings that can be applied using cheaper and portable techniques, such as Twin Wire Arc Spray technology (TWAS). In this study, we compare selected NiCr-based coatings and two uncoated steel substrates (steel 1.7715 and 1.

Dielectric Spectroscopy of Calcium Titanate Processed by Spark Plasma Sintering.

Calcium titanate (CaTiO) powder was compacted by spark plasma sintering (SPS). The resulting products were subjected to the phase stability study and dielectric characterization. The change in temperature of SPS between 1100 °C and 1250 °C had a clear and straightforward effect on density, porosity, relative permittivity, loss tangent, and DC resistivity.

Thermal Properties of Illite-Zeolite Mixtures up to 1100 °C.

Illitic clays are the commonly used material in building ceramics. Zeolites are microporous, hydrated crystalline aluminosilicates, they are widely used due to their structure and absorption properties. In this study, illitic clay (Füzérradvány, Hungary) was mixed with natural zeolite (Nižný Hrabovec, Slovakia) with up to 50 wt.

High-Temperature Cycling of Plasma Sprayed Multilayered NiCrAlY/YSZ/GZO/YAG Thermal Barrier Coatings Prepared from Liquid Feedstocks.

High-enthalpy hybrid water/argon-stabilized plasma (WSP-H) torch may be used for efficient deposition of coatings from dry powders, suspensions, and solutions. WSP-H torch was used to deposit two complete thermal barrier coatings (TBCs) with multilayered top-coat. NiCrAlY was used as bondcoat and deposited on nickel-based superalloy substrates.

Young's Modulus of Different Illitic Clays during Heating and Cooling Stage of Firing.

Dynamical thermomechanical analysis of 5 illite-based clays from deposits in Slovakia, Estonia, Latvia, and Hungary is presented. The clays consist of illite (37-80 mass%), quartz (12-48 mass%), K-feldspar (4-13 mass%), kaolinite (0-18 mass%), and calcite (0-3 mass%). Young's modulus is measured during the heating and cooling stages of firing (25 °C → 1100 °C → 25 °C).

Effect of Short Attritor-Milling of Magnesium Alloy Powder Prior to Spark Plasma Sintering.

The spark plasma sintering (SPS) technique was employed to prepare compacts from (i) gas-atomized and (ii) attritor-milled AE42 magnesium powder. Short attritor-milling was used mainly to disrupt the MgO shell covering the powder particles and, in turn, to enhance consolidation during sintering. Compacts prepared by SPS from the milled powder featured finer microstructures than compacts consolidated from gas-atomized powder (i.

Phase, Composition and Structure Changes of CoCrNi-Based Concentrated Alloys Resulting from High Temperature Oxidation.

In this work, CoCrNi, FeCoCrNi and CoCrFeMnNi concentrated alloys with a Y-Ti oxide particle dispersion were prepared by mechanical alloying and Spark Plasma Sintering. The alloy consists of an FCC Ni-based matrix with a Y-Ti oxide dispersion and additional phases of CrC and CrO. The effect of Fe, Mn, and Y-Ti oxide particles on the formation of oxide scales and the composition of the adjacent CoCrNi and FeCoCrNi alloys was studied.

Influence of Glass Additions on Illitic Clay Ceramics.

A mixture of an illitic clay and waste glass was prepared and studied during the sintering process. The illitic clay, from the Liepa deposit (Latvia), and green glass waste (GW) were disintegrated to obtain a homogeneous mixture. The addition of disintegrated GW (5-15 wt% in the mixture) led to a reduction in the intensive sintering temperature, from 900 to 860 °C, due to a significant decrease in the glass viscosity.

The Effect of Processing Route on Properties of HfNbTaTiZr High Entropy Alloy.

High entropy alloys (HEA) have been one of the most attractive groups of materials for researchers in the last several years. Since HEAs are potential candidates for many (e.g.

Improvement of Mechanical Properties of Plasma Sprayed AlO-ZrO-SiO Amorphous Coatings by Surface Crystallization.

Ceramic AlO-ZrO-SiO coatings with near eutectic composition were plasma sprayed using hybrid water stabilized plasma torch (WSP-H). The as-sprayed coatings possessed fully amorphous microstructure which can be transformed to nanocrystalline by further heat treatment. The amorphous/crystalline content ratio and the crystallite sizes can be controlled by a specific choice of heat treatment conditions, subsequently leading to significant changes in the microstructure and mechanical properties of the coatings, such as hardness or wear resistance.

Microstructure and Room Temperature Mechanical Properties of Different 3 and 4 Element Medium Entropy Alloys from HfNbTaTiZr System.

Refractory high entropy alloys (HEA) are promising materials for high temperature applications. This work presents investigations of the room temperature tensile mechanical properties of selected 3 and 4 elements medium entropy alloys (MEA) derived from the HfNbTaTiZr system. Tensile testing was combined with fractographic and microstructure analysis, using scanning electron microscope (SEM), wavelength dispersive spectroscope (WDS) and X-Ray powder diffraction (XRD).

The Influence of Milling and Spark Plasma Sintering on the Microstructure and Properties of the Al7075 Alloy.

The compact samples of an Al7075 alloy were prepared by a combination of gas atomization, high energy milling, and spark plasma sintering. The predominantly cellular morphology observed in gas atomized powder particles was completely changed by mechanical milling. The continuous-like intermetallic phases present along intercellular boundaries were destroyed; nevertheless, a small amount of Mg(Zn,Cu,Al)₂ phase was observed also in the milled powder.

Nanocrystalline Al7075 + 1 wt % Zr Alloy Prepared Using Mechanical Milling and Spark Plasma Sintering.

The microstructure, phase composition, and microhardness of both gas-atomized and mechanically milled powders of the Al7075 + 1 wt % Zr alloy were investigated. The gas-atomized powder exhibited a cellular microstructure (grain size of a few µm) with layers of intermetallic phases along the cell boundaries. Mechanical milling (400 revolutions per minute (RPM)/8 h) resulted in a grain size reduction to the nanocrystalline range (20 to 100 nm) along with the dissolution of the intermetallic phases.

Spark Plasma Sintering of a Gas Atomized Al7075 Alloy: Microstructure and Properties.

The powder of an Al7075 alloy was prepared by gas atomization. A combination of cellular, columnar, and equiaxed dendritic-like morphology was observed in individual powder particles with continuous layers of intermetallic phases along boundaries. The cells are separated predominantly by high-angle boundaries, the areas with dendritic-like morphology usually have a similar crystallographic orientation.

Microhardness and In Vitro Corrosion of Heat-Treated Mg-Y-Ag Biodegradable Alloy.

Magnesium alloys are promising candidates for biodegradable medical implants which reduce the necessity of second surgery to remove the implants. Yttrium in solid solution is an attractive alloying element because it improves mechanical properties and exhibits suitable corrosion properties. Silver was shown to have an antibacterial effect and can also enhance the mechanical properties of magnesium alloys.