Electron beam modification of the structure and properties of silumins with various silicon concentrations

This work intended to analyse the structure and properties of hypoeutectic silumin treated by a pulsed electron beam. The study has shown that the silumin surface modified by a pulsed electron beam fractures due to the formation and propagation of microcracks along the boundaries of high-speed crystallization cells. In the untreated material (the concentration of silicon in the alloy is irrelevant) microcracks tend to originate and propagate along the phase boundaries between aluminum and silicon. The research has revealed that the plasticity of irradiated AK5M2 silumin is 1.6 higher and the strength is 1.1 lower than these characteristics of the untreated material; the irradiated AK10M2H silumin fractures at higher (by ≈ 30%) applied stress and higher (by 30%) plastic deformation than the untreated material.

Effect of Boron and Vanadium Addition on Friction-Wear Properties of the Coating AlCrN for Special Applications

Cutting tools have long been coated with an AlCrN hard coating system that has good mechanical and tribological qualities. Boron (B) and vanadium (V) additions to AlCrN coatings were studied for their mechanical and tribological properties. Cathodic multi-arc evaporation was used to successfully manufacture the AlCrBN and AlCrVN coatings. These multicomponent coatings were applied to the untreated and plasma-nitrided surfaces of HS6-5-2 and H13 steels, respectively. Nanoindentation and Vickers micro-hardness tests were used to assess the mechanical properties of the materials. Ball-on-flat wear tests with WC-Co balls as counterparts were used to assess the friction-wear capabilities. Nanoindentation tests demonstrated that AlCrBN coating has a higher hardness (HIT 40.9 GPa) than AlCrVN coating (39.3 GPa). Steels’ wear resistance was significantly increased by a hybrid treatment that included plasma nitriding and hard coatings. The wear volume was 3% better for the AlCrBN coating than for the AlCrVN coating on H13 nitrided steel, decreasing by 89% compared to the untreated material. For HS6-5-2 steel, the wear volume was almost the same for both coatings but decreased by 77% compared to the untreated material. Boron addition significantly improved the mechanical, tribological, and adhesive capabilities of the AlCrN coating.

Enhancement of Mechanical Properties of Pure Aluminium through Contactless Melt Sonicating Treatment

A new contactless ultrasonic sonotrode method was previously designed to provide cavitation conditions inside liquid metal. The oscillation of entrapped gas bubbles followed by their final collapse causes extreme pressure changes leading to de-agglomeration and the dispersion of oxide films. The forced wetting of particle surfaces and degassing are other mechanisms that are considered to be involved. Previous publications showed a significant decrease in grain size using this technique. In this paper, the authors extend this research to strength measurements and demonstrate an improvement in cast quality. Degassing effects are also interpreted to illustrate the main mechanisms involved in alloy strengthening. The mean values and Weibull analysis are presented where appropriate to complete the data. The test results on cast Al demonstrated a maximum of 48% grain refinement, a 28% increase in elongation compared to 16% for untreated material and up to 17% increase in ultimate tensile strength (UTS). Under conditions promoting degassing, the hydrogen content was reduced by 0.1 cm3/100 g.

Laser Processing of Ni-Based Superalloy Surfaces Susceptible to Stress Concentration

Reliable and resilient constructions are basic for ensuring the safety of various structures. The superalloys are used as constructive materials due to their superb mechanical properties and endurance. However, even these materials can have certain areas where the stress concentration is higher than expected, such as drilling holes, which are common in various structures that need additional enhancement. Surface laser modifications of the areas surrounding the holes drilled in Nimonic 263 sheets are done by pulsed picosecond and nanosecond Nd:YAG laser irradiations with pulse durations of 170 ps and ≤8 ns, respectively. Following the laser surface treatment, the effectiveness of the enhancement was analyzed by the microhardness test and the deformation test. The results show that the deformation and stress values are decreased by 25−40 percent, showing the improvement in the resilience to deformation. The Vickers microhardness test results indicate an improvement in the Nimonic 263 microhardness. The dimensions of the microcracks are higher for the untreated material in comparison to the laser-treated material.

Biological Cloth Face Coverings - The Reduction of SARS-CoV-2 and Influenza (H1N1) Infectivity by ViruferrinTM Treatment

Fabric material was coated with Viruferrin™ and tested for its inactivating properties against the pandemic severe acute respiratory syndrome 2 (SARS-CoV-2) and influenza A viruses. A statistically significant (p<0.0001) decrease in the number of infectious virus particles exposed to Viruferrin-treated fabric when compared with the cotton control for both SARS-CoV-2 and influenza A viruses was observed. For both SARS-CoV-2 and influenza A, Viruferrin-treated fabrics experienced a > 99% virus reduction without saliva after five minutes of contact when compared to the positive control at time point 0. Furthermore, the reusability of the Viruferrin treated fabric was demonstrated by stability for up to 10 washes. The level of anti-viral (SARS-CoV-2) activity remained constant from 5 to 10 washes and demonstrated a significant difference (p<0.0001) from the unwashed untreated material. Applications for this treated fabric are far-reaching, and as a biological face covering offers not only a unique 2-way protection but also is unlikely to cause onward touch transmission.

Iron can be microbially extracted from Lunar and Martian regolith simulants and 3D printed into tough structural materials

In-situ resource utilization (ISRU) is increasingly acknowledged as an essential requirement for the construction of sustainable extra-terrestrial colonies. Even with decreasing launch costs, the ultimate goal of establishing colonies must be the usage of resources found at the destination of interest. Typical approaches towards ISRU are often constrained by the mass and energy requirements of transporting processing machineries, such as rovers and massive reactors, and the vast amount of consumables needed. Application of self-reproducing bacteria for the extraction of resources is a promising approach to avoid these pitfalls. In this work, the bacterium Shewanella oneidensis was used to reduce three different types of Lunar and Martian regolith simulants, allowing for the magnetic extraction of iron-rich materials. The quantity of bacterially extracted material was up to 5.8 times higher and the total iron concentration was up to 43.6% higher in comparison to untreated material. The materials were 3D printed into cylinders and the mechanical properties were tested, resulting in a 396 ± 115% improvement in compressive strength in the bacterially treated samples. This work demonstrates a proof of concept for the on-demand production of construction and replacement parts in space exploration.

The Influence of High-Temperature Nitrogen Plasma-Based Ion Implantation on Niobium Creep Behavior

Niobium has been considered for applications in the aerospace sector, but its use at high temperatures is restricted, due to the great affinity of refractory metals with oxygen, which results in the formation of oxide layers and a decrease in their mechanical resistances. In the present work, Nb samples were submitted to High-Temperature Nitrogen Plasma-Based Ion Implantation (HT-NPBII). The process runs at a working pressure between 3 and 4 mbar and negative high voltage pulses of 7 kV/30 μs/300 Hz were applied to samples heated to 1000°C, at treatment times of 1 h, 4 h, and 8 h, respectively. Microstructural and mechanical characterizations of the treated samples revealed the formation of a layer of Nb2N, with 3.0 μm thickness and increase in the surface hardness from 225 HV for the untreated material up to about 2498 HV, for samples treated during 8 h. Creep tests were performed at 500°C and with loads varying from 25 to 40 MPa. Results indicated a decrease in the secondary creep rate for treated specimens when compared to the untreated ones. This behavior can be attributed to the formation of a nitride layer on the surface of Nb that acts as barrier to avoid the oxygen diffusion into the material under high temperature conditions.

ANALISA REKAYASA SIFAT MEKANIK BAJA AISI 4140 DENGAN VARIASI SUHU TEMPERING UNTUK MENINGKATKAN KEULETAN DAN KEKERASAN MATERIAL

Steel is a type of material that is widely used as a main material in the manufacture of various kinds of industrial and automatic machinery spare parts. Some mechanical properties of steel that are often used in design are hardness, ductility and toughness. Often in a design, we have difficulty getting steel with mechanical properties that are appropriate with the design. For this reason, engineering carried out mechanical properties engineering, to obtain steel in accordance with design calculations. AISI 4140 steel is a medium alloy steel. This steel is often used for industrial and automotive machinery parts. This research engineered the mechanical properties of the steel, namely the hardness and ductility of the material. The process is carried out by conducting steel hardening at 850 °C followed by rapid cooling with water media. After that, tempering at temperatures of 300 ᵒC, 400ᵒC and 500ᵒC by cooling together with the furnace. The result is hardness and tensile strength of the material has increased, when compared with untreated material. This method is effectively used to obtain mechanical strength values in accordance with technical planning calculations. . Keywords: Tempering, AISI 4140, Mechanical Properties Engineering

INFLUENCE OF VACUUM ACTIVATED DIFFUSION CHROMING ON MECHANICAL PROPERTIES OF THE SURFACE OF STEEL 25X1MF

In the work, the surface of samples made of 25X1MF steel was saturated with chromium. For this, the method of vacuum activated diffusion chromium plating was used. In this process, sodium chloride was used as an activator. It was found that vacuum activated diffusion chromium plating of samples made of 25Kh1MF steel leads to the formation of a surface layer containing from 87 to 97 wt.% of this element. It was found that an increase in the temperature of the process and its duration leads to an increase in the chromium content on the surface of the samples. The tests showed that in the case of cavitations-erosion effects on the surface of chrome-plated samples of steel 25X1MF they have higher resistance. With abrasive wear, the resistance of the chrome-plated steel surface is 1.8 to 3 times higher compared to untreated material.

Abrasive Wear Behavior of Cryogenically Treated Boron Steel (30MnCrB4) Used for Rotavator Blades

Rotavator blades are prone to significant wear because of the abrasive nature of sand particles. The aim of this research work is to investigate the effect of cryogenic treatment and post tempering on abrasive wear behavior, in the presence of angular quartz sand (grain size of 212–425 μm), of rotavator blade material of boron steel (30MnCrB4). Cryogenic treatment has caused an improvement in the abrasive wear resistance and microhardness of 30MnCrB4 by 60% and 260.73%, respectively, compared to untreated material due to enhancement in hardness, the conversion of retained austenite into martensite, and the precipitation of secondary carbides in boron steel after exposure to cryogenic temperature. Economic analysis justifies the additional cost of cryogenic treatment.